Flux Tower Eddy Covariance and Meteorological Measurements for Barrow, Alaska: 2012-2016

DOE Data Explorer

Dengel, Sigrid; Torn, Margaret; Billesbach, David

2017-08-24

The dataset contains half-hourly eddy covariance flux measurements and determinations, companion meteorological measurements, and ancillary data from the flux tower (US-NGB) on the Barrow Environmental Observatory at Barrow (Utqiagvik), Alaska for the period 2012 through 2016. Data have been processed using EddyPro software and screened by the contributor. The flux tower sits in an Arctic coastal tundra ecosystem. This dataset updates a previous dataset by reprocessing a longer period of record in the same manner. Related dataset "Eddy-Covariance and auxiliary measurements, NGEE-Barrow, 2012-2013" DOI:10.5440/1124200.

Two Different Approaches to Teaching Final-Year Projects for Mechanical Engineers and Biotechnologists at Ngee Ann Polytechnic--Case Studies Approach.

ERIC Educational Resources Information Center

Walsh, Kath; Rebaczonok-Padulo, Michael

1993-01-01

Ngee Ann Polytechnic, a leading postsecondary technical institution in Singapore, offers English for academic and occupational purposes to prepare students for writing their final year projects. This article discusses the approaches used in Mechanical Engineering and Biotechnology projects. A sample exercise is appended. (Contains two references.)…

Two Different Approaches to Teaching Final-Year Projects for Mechanical Engineers and Biotechnologists at Ngee Ann Polytechnic: Case Studies Approach.

ERIC Educational Resources Information Center

Walsh, Kath; Rebaczonok-Padulo, Michael

The Oral and Written Communication (OWC) course at Ngee Ann Polytechnic was originally intended to equip students with occupational skills (e.g., report- and letter-writing, public speaking) but has expanded to be a course aimed at helping third-year mechanical engineering students to develop third-year project reports. This has been done through…

Effect of Freeze-Thaw Cycles on Soil Nitrogen Reactive Transport in a Polygonal Arctic Tundra Ecosystem at Barrow AK Using 3-D Coupled ALM-PFLOTRAN

NASA Astrophysics Data System (ADS)

Yuan, F.; Wang, G.; Painter, S. L.; Tang, G.; Xu, X.; Kumar, J.; Bisht, G.; Hammond, G. E.; Mills, R. T.; Thornton, P. E.; Wullschleger, S. D.

2017-12-01

In Arctic tundra ecosystem soil freezing-thawing is one of dominant physical processes through which biogeochemical (e.g., carbon and nitrogen) cycles are tightly coupled. Besides hydraulic transport, freezing-thawing can cause pore water movement and aqueous species gradients, which are additional mechanisms for soil nitrogen (N) reactive-transport in Tundra ecosystem. In this study, we have fully coupled an in-development ESM(i.e., Advanced Climate Model for Energy, ACME)'s Land Model (ALM) aboveground processes with a state-of-the-art massively parallel 3-D subsurface thermal-hydrology and reactive transport code, PFLOTRAN. The resulting coupled ALM-PFLOTRAN model is a Land Surface Model (LSM) capable of resolving 3-D soil thermal-hydrological-biogeochemical cycles. This specific version of PFLOTRAN has incorporated CLM-CN Converging Trophic Cascade (CTC) model and a full and simple but robust soil N cycle. It includes absorption-desorption for soil NH4+ and gas dissolving-degasing process as well. It also implements thermal-hydrology mode codes with three newly-modified freezing-thawing algorithms which can greatly improve computing performance in regarding to numerical stiffness at freezing-point. Here we tested the model in fully 3-D coupled mode at the Next Generation Ecosystem Experiment-Arctic (NGEE-Arctic) field intensive study site at the Barrow Environmental Observatory (BEO), AK. The simulations show that: (1) synchronous coupling of soil thermal-hydrology and biogeochemistry in 3-D can greatly impact ecosystem dynamics across polygonal tundra landscape; and (2) freezing-thawing cycles can add more complexity to the system, resulting in greater mobility of soil N vertically and laterally, depending upon local micro-topography. As a preliminary experiment, the model is also implemented for Pan-Arctic region in 1-D column mode (i.e. no lateral connection), showing significant differences compared to stand-alone ALM. The developed ALM-PFLOTRAN coupling codes embeded within ESM will be used for Pan-Arctic regional evaluation of climate change-caused ecosystem responses and their feedbacks to climate system at various scales.

Frost Tables, Barrow, Alaska, NGEE Areas B, C and D for 2012, 2013, 2014, Final Version, 20150312

DOE Data Explorer

Liljedahl, Anna

2014-03-24

This dataset represent spatially intensive thaw depth surveys with individual point measurements spaced approximately 0.5 m apart. The three approximate10x10m grids cover an ice wedge and a portion of its two neighboring polygons. The file contains thaw depth, frost table elevation, ground surface elevation, active layer depth and surface water inundation across three seasons (2012, 2013 and 2014) at Barrow NGEE Areas B, C and D.

NGEE Arctic TIR and Digital Photos, Drained Thaw Lake Basin, Barrow, Alaska, July 2015

DOE Data Explorer

Shawn Serbin; Wil Lieberman-Cribbin; Kim Ely; Alistair Rogers

2016-11-01

FLIR thermal infrared (TIR), digital camera photos, and plot notes across the Barrow, Alaska DTLB site. Data were collected together with measurements of canopy spectral reflectance (see associated metadata record (NGEE Arctic HR1024i Canopy Spectral Reflectance, Drained Thaw Lake Basin, Barrow, Alaska, July 2015 ). Data contained within this archive include exported FLIR images (analyzed with FLIR-Tools), digital photos, TIR report, and sample notes. Further TIR image analysis can be conducted in FLIR-Tools.

NGEE Arctic Tram: Continuous Soil Moisture and Temperature Measurements across Low- and High-Centered Polygonal Ground, Barrow, Alaska, 2014-2016

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baptiste Dafflon; Margaret Torn

This data set reports the continuous soil moisture and temperature measurements collected from August of 2014 to September of 2016 along the footprint of the NGEE Arctic Tram. Soil moisture and temperature sensors are installed adjacent to the Tram at 8 locations of varying land surface types across the low-centered and high-centered polygonal ground. While the Tram operates seasonally these soil measurements are recorded year around. Data for the remainder of 2016 and 2017 will be added when available.

Visible to Near-infrared Spectral Reflectance, NGEE-Arctic Tram, Barrow, Alaska, 2015-2017

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meng, Ran; McMahon, Andrew; Rogers, Alistair

Canopy spectral reflectance collected from the NGEE-Arctic automated tram platform using a PP-Systems UniSpec-DC spectrometer. Downwelling radiance was measured using a 2 meter fiber optic cable connected to a cosine diffuser. Upwelling (i.e. reflected) radiance was measured using a 2 meter cable connected to a 12 degree field-of-view (FOV) lens. Canopy reflectance was calculated using the ratio of upwelling to downwelling radiance measured over a 99.99% reflectance Spectralon standard measured at the start of each measurement set.

Estimating the spatial distribution of soil organic matter density and geochemical properties in a polygonal shaped Arctic Tundra using core sample analysis and X-ray computed tomography

NASA Astrophysics Data System (ADS)

Soom, F.; Ulrich, C.; Dafflon, B.; Wu, Y.; Kneafsey, T. J.; López, R. D.; Peterson, J.; Hubbard, S. S.

2016-12-01

The Arctic tundra with its permafrost dominated soils is one of the regions most affected by global climate change, and in turn, can also influence the changing climate through biogeochemical processes, including greenhouse gas release or storage. Characterization of shallow permafrost distribution and characteristics are required for predicting ecosystem feedbacks to a changing climate over decadal to century timescales, because they can drive active layer deepening and land surface deformation, which in turn can significantly affect hydrological and biogeochemical responses, including greenhouse gas dynamics. In this study, part of the Next-Generation Ecosystem Experiment (NGEE-Arctic), we use X-ray computed tomography (CT) to estimate wet bulk density of cores extracted from a field site near Barrow AK, which extend 2-3m through the active layer into the permafrost. We use multi-dimensional relationships inferred from destructive core sample analysis to infer organic matter density, dry bulk density and ice content, along with some geochemical properties from nondestructive CT-scans along the entire length of the cores, which was not obtained by the spatially limited destructive laboratory analysis. Multi-parameter cross-correlations showed good agreement between soil properties estimated from CT scans versus properties obtained through destructive sampling. Soil properties estimated from cores located in different types of polygons provide valuable information about the vertical distribution of soil and permafrost properties as a function of geomorphology.

Effects of spatial and temporal resolution on simulated feedbacks from polygonal tundra.

NASA Astrophysics Data System (ADS)

Coon, E.; Atchley, A. L.; Painter, S. L.; Karra, S.; Moulton, J. D.; Wilson, C. J.; Liljedahl, A.

2014-12-01

Earth system land models typically resolve permafrost regions at spatial resolutions grossly larger than the scales of topographic variation. This observation leads to two critical questions: How much error is introduced by this lack of resolution, and what is the effect of this approximation on other coupled components of the Earth system, notably the energy balance and carbon cycle? Here we use the Arctic Terrestrial Simulator (ATS) to run micro-topography resolving simulations of polygonal ground, driven by meteorological data from Barrow, AK, to address these questions. ATS couples surface and subsurface processes, including thermal hydrology, surface energy balance, and a snow model. Comparisons are made between one-dimensional "column model" simulations (similar to, for instance, CLM or other land models typically used in Earth System models) and higher-dimensional simulations which resolve micro-topography, allowing for distributed surface runoff, horizontal flow in the subsurface, and uneven snow distribution. Additionally, we drive models with meteorological data averaged over different time scales from daily to weekly moving windows. In each case, we compare fluxes important to the surface energy balance including albedo, latent and sensible heat fluxes, and land-to-atmosphere long-wave radiation. Results indicate that spatial topography variation and temporal variability are important in several ways. Snow distribution greatly affects the surface energy balance, fundamentally changing the partitioning of incoming solar radiation between the subsurface and the atmosphere. This has significant effects on soil moisture and temperature, with implications for vegetation and decomposition. Resolving temporal variability is especially important in spring, when early warm days can alter the onset of snowmelt by days to weeks. We show that high-resolution simulations are valuable in evaluating current land models, especially in areas of polygonal ground. This work was supported by LANL Laboratory Directed Research and Development Project LDRD201200068DR and by the The Next-Generation Ecosystem Experiments (NGEE Arctic) project. NGEE-Arctic is supported by the Office of Biological and Environmental Research in the DOE Office of Science. LA-UR-14-26227.

Active Layer Soil Carbon and Nutrient Mineralization, Barrow, Alaska, 2012

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stan D. Wullschleger; Holly M. Vander Stel; Colleen Iversen

This data set consists of bulk soil characteristics as well as carbon and nutrient mineralization rates of active layer soils manually collected from the field in August, 2012, frozen, and then thawed and incubated across a range of temperatures in the laboratory for 28 day periods in 2013-2015. The soils were collected from four replicate polygons in each of the four Areas (A, B, C, and D) of Intensive Site 1 at the Next-Generation Ecosystem Experiments (NGEE) Arctic site near Barrow, Alaska. Soil samples were coincident with the established Vegetation Plots that are located in center, edge, and trough microtopographymore » in each polygon. Data included are 1) bulk soil characteristics including carbon, nitrogen, gravimetric water content, bulk density, and pH in 5-cm depth increments and also by soil horizon, 2) carbon, nitrogen, and phosphorus mineralization rates for soil horizons incubated aerobically (and in one case both aerobically and anaerobically) for 28 days at temperatures that included 2, 4, 8, and 12 degrees C. Additional soil and incubation data are forthcoming. They will be available when published as part of another paper that includes additional replicate analyses.« less

In Situ Soil Moisture and Thaw Depth Measurements Coincident with Airborne SAR Data Collections, Barrow and Seward Peninsulas, Alaska, 2017

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cathy Wilson; Julian Dann; Robert Bolton

The in-situ soil moisture and thaw depth measurements provided in this dataset were collected coincident with airborne overflights of L- and P-band SAR instruments at the NGEE Arctic study site near Barrow, on the North Slope, and at the three study sites on the Seward Peninsula, Alaska. Field measurements and flights were conducted during the summer of 2017 as a collaboration between the NASA ABoVE Project's Airborne SAR Campaign and the NGEE Arctic Project. ABoVE protocols for establishing field measurement plots were followed.

Data System Architectures: Recent Experiences from Data Intensive Projects

NASA Astrophysics Data System (ADS)

Palanisamy, G.; Frame, M. T.; Boden, T.; Devarakonda, R.; Zolly, L.; Hutchison, V.; Latysh, N.; Krassovski, M.; Killeffer, T.; Hook, L.

2014-12-01

U.S. Federal agencies are frequently trying to address new data intensive projects that require next generation of data system architectures. This presentation will focus on two new such architectures: USGS's Science Data Catalog (SDC) and DOE's Next Generation Ecological Experiments - Arctic Data System. The U.S. Geological Survey (USGS) developed a Science Data Catalog (data.usgs.gov) to include records describing datasets, data collections, and observational or remotely-sensed data. The system was built using service oriented architecture and allows USGS scientists and data providers to create and register their data using either a standards-based metadata creation form or simply to register their already-created metadata records with the USGS SDC Dashboard. This dashboard then compiles the harvested metadata records and sends them to the post processing and indexing service using the JSON format. The post processing service, with the help of various ontologies and other geo-spatial validation services, auto-enhances these harvested metadata records and creates a Lucene index using the Solr enterprise search platform. Ultimately, metadata is made available via the SDC search interface. DOE's Next Generation Ecological Experiments (NGEE) Arctic project deployed a data system that allows scientists to prepare, publish, archive, and distribute data from field collections, lab experiments, sensors, and simulated modal outputs. This architecture includes a metadata registration form, data uploading and sharing tool, a Digital Object Identifier (DOI) tool, a Drupal based content management tool (http://ngee-arctic.ornl.gov), and a data search and access tool based on ORNL's Mercury software (http://mercury.ornl.gov). The team also developed Web-metric tools and a data ingest service to visualize geo-spatial and temporal observations.

Characterization And Partitioning Of CH4 And CO2 Eddy Flux Data Measured at NGEE-Arctic Sites

NASA Astrophysics Data System (ADS)

Dengel, S.; Chafe, O.; Curtis, J. B.; Biraud, S.; Torn, M. S.; Wullschleger, S. D.

2017-12-01

The high latitudes are experiencing rapid warming with permafrost ecosystems being highly vulnerable to this change. Since the advancement in Eddy Covariance (EC) measurements, the number of high latitude sites measuring greenhouse gases and energy (CO2, CH4 and H2O) fluxes is steadily increasing, with new sites being established each year. Data from these sites are not only valuable for annual carbon budget calculations, but also vital to the modeling community for improving their predictions of emission rates and trends. CH4 flux measurements are not as straightforward as CO2 fluxes. They tend to be less predictable or as easily interpretable as CO2 fluxes. Understanding CH4 emission patterns are often challenging. Moreover, gas flux fluctuations are spatially and temporally diverse, and in many cases event-based. An improvement in understanding would also contribute to improvements in the fidelity of model predictions. These rely on having high quality data, and thus will entail developing new QA/QC and gap-filling methods for Arctic systems, in particularly for CH4. Contributing to these challenges is the limited number of ancillary measurements carried out at many sites and the lack of standardized data processing, QA/QC, and gap-filling procedures, in particular for CH4. CO2, CH4, and energy flux measurements are ongoing at, both NGEE-Arctic/AmeriFlux, US-NGB (Arctic coastal plain), and US-NGC (subarctic tussock tundra) sites. The sites, with underlying continuous permafrost, show a high degree of inter-annual and seasonal variability in CH4 fluxes. In order to interpret this variability, we apply a variety of models, such as footprint characterization, generalized additive models, as well as artificial neural networks, in an attempt to decipher these diverse fluxes, patterns and events.

Hydraulic Conductivity Measurements Barrow 2014

DOE Data Explorer

Katie McKnight; Tim Kneafsey; Craig Ulrich; Jil Geller

2015-02-22

Six individual ice cores were collected from Barrow Environmental Observatory in Barrow, Alaska, in May of 2013 as part of the Next Generation Ecosystem Experiment (NGEE). Each core was drilled from a different location at varying depths. A few days after drilling, the cores were stored in coolers packed with dry ice and flown to Lawrence Berkeley National Laboratory (LBNL) in Berkeley, CA. 3-dimensional images of the cores were constructed using a medical X-ray computed tomography (CT) scanner at 120kV. Hydraulic conductivity samples were extracted from these cores at LBNL Richmond Field Station in Richmond, CA, in February 2014 by cutting 5 to 8 inch segments using a chop saw. Samples were packed individually and stored at freezing temperatures to minimize any changes in structure or loss of ice content prior to analysis. Hydraulic conductivity was determined through falling head tests using a permeameter [ELE International, Model #: K-770B]. After approximately 12 hours of thaw, initial falling head tests were performed. Two to four measurements were collected on each sample and collection stopped when the applied head load exceeded 25% change from the original load. Analyses were performed between 2 to 3 times for each sample. The final hydraulic conductivity calculations were computed using methodology of Das et al., 1985.

Modeling hydrological controls on vegetation distribution across topography in Seward Peninsula, Alaska

NASA Astrophysics Data System (ADS)

Mekonnen, Z. A.; Riley, W. J.; Grant, R. F.; Salmon, V. G.; Iversen, C. M.; Biraud, S.; Breen, A. L.

2017-12-01

Observed changes in vegetation affect carbon and nutrient cycles in diverse landscapes of northern ecosystems. These changes can be affected by topography and landscape hydrology. We applied a coupled transect version of the ecosystem model ecosys in a landscape underlain by impermeable permafrost at Kougarok, Alaska to examine hydrological controls on watershed-scale vegetation distributions. Our preliminary results indicate strong relationships between vegetation distribution and soil physical and hydraulic properties that control water, nutrients, and energy flows across the hillslope. Modeled differences in aboveground biomass across the Kougarok hillslope had a good agreement (R2 0.80) with preliminary biomass measurements from the NGEE-Arctic project in summer 2016. Low soil water content from shallower soil depth and lateral flow of water and nutrients in the upper slope position of the hillslope resulted in water stress and low N mineralization for plants with deeper roots. The middle slope position had intermediate soil moisture from deeper soil and higher N mineralization that favoured fast-growing and deep-rooted plants. The gentle slope and deeper soil in the lower slope position resulted in saturated soil, thus reduced O2 for microbes, hence favouring plants with higher root porosity. Earth system models that do not account for the underlying mechanisms of surface and sub-surface flows of water, nutrients, and energy may not predict these types of dynamics in Arctic ecosystems.

Multivariate Spatio-Temporal Clustering: A Framework for Integrating Disparate Data to Understand Network Representativeness and Scaling Up Sparse Ecosystem Measurements

NASA Astrophysics Data System (ADS)

Hoffman, F. M.; Kumar, J.; Maddalena, D. M.; Langford, Z.; Hargrove, W. W.

2014-12-01

Disparate in situ and remote sensing time series data are being collected to understand the structure and function of ecosystems and how they may be affected by climate change. However, resource and logistical constraints limit the frequency and extent of observations, particularly in the harsh environments of the arctic and the tropics, necessitating the development of a systematic sampling strategy to maximize coverage and objectively represent variability at desired scales. These regions host large areas of potentially vulnerable ecosystems that are poorly represented in Earth system models (ESMs), motivating two new field campaigns, called Next Generation Ecosystem Experiments (NGEE) for the Arctic and Tropics, funded by the U.S. Department of Energy. Multivariate Spatio-Temporal Clustering (MSTC) provides a quantitative methodology for stratifying sampling domains, informing site selection, and determining the representativeness of measurement sites and networks. We applied MSTC to down-scaled general circulation model results and data for the State of Alaska at a 4 km2 resolution to define maps of ecoregions for the present (2000-2009) and future (2090-2099), showing how combinations of 37 bioclimatic characteristics are distributed and how they may shift in the future. Optimal representative sampling locations were identified on present and future ecoregion maps, and representativeness maps for candidate sampling locations were produced. We also applied MSTC to remotely sensed LiDAR measurements and multi-spectral imagery from the WorldView-2 satellite at a resolution of about 5 m2 within the Barrow Environmental Observatory (BEO) in Alaska. At this resolution, polygonal ground features—such as centers, edges, rims, and troughs—can be distinguished. Using these remote sensing data, we up-scaled vegetation distribution data collected on these polygonal ground features to a large area of the BEO to provide distributions of plant functional types that can be used to parameterize ESMs. In addition, we applied MSTC to 4 km2 global bioclimate data to define global ecoregions and understand the representativeness of CTFS-ForestGEO, Fluxnet, and RAINFOR sampling networks. These maps identify tropical forests underrepresented in existing observations of individual and combined networks.

Influences of Moisture Regimes and Functional Plant Types on Nutrient Cycling in Permafrost Regions

NASA Astrophysics Data System (ADS)

McCaully, R. E.; Arendt, C. A.; Newman, B. D.; Heikoop, J. M.; Wilson, C. J.; Sevanto, S.; Wales, N. A.; Wullschleger, S.

2017-12-01

In the permafrost-dominated Arctic, climatic feedbacks exist between permafrost, soil moisture, functional plant type and presence of nutrients. Functional plant types present within the Arctic regulate and respond to changes in hydrologic regimes and nutrient cycling. Specifically, alders are a member of the birch family that use root nodules to fix nitrogen, which is a limiting nutrient strongly linked to fertilizing Arctic ecosystems. Previous investigations in the Seward Peninsula, AK show elevated presence of nitrate within and downslope of alder patches in degraded permafrost systems, with concentrations an order of magnitude greater than that of nitrate measured above these patches. Further observations within these degraded permafrost systems are crucial to assess whether alders are drivers of, or merely respond to, nitrate fluxes. In addition to vegetative feedbacks with nitrate supply, previous studies have also linked low moisture content to high nitrate production. Within discontinuous permafrost regions, the absence of permafrost creates well-drained regions with unsaturated soils whereas the presence of permafrost limits vertical drainage of soil-pore water creating elevated soil moisture content, which likely corresponds to lower nitrate concentrations. We investigate these feedbacks further in the Seward Peninsula, AK, through research supported by the United States Department of Energy Next Generation Ecosystem Experiment (NGEE) - Arctic. Using soil moisture and thaw depth as proxies to determine the extent of permafrost degradation, we identify areas of discontinuous permafrost over a heterogeneous landscape and collect co-located soilwater chemistry samples to highlight the complex relationships that exist between alder patches, soil moisture regimes, the presence of permafrost and available nitrate supply. Understanding the role of nitrogen in degrading permafrost systems, in the context of both vegetation present and soil moisture, is crucial to understand the impacts of a warming climate on biogeochemical cycling in permafrost regions.

Effect of soil property uncertainties on permafrost thaw projections: a calibration-constrained analysis: Modeling Archive

DOE Data Explorer

J.C. Rowland; D.R. Harp; C.J. Wilson; A.L. Atchley; V.E. Romanovsky; E.T. Coon; S.L. Painter

2016-02-02

This Modeling Archive is in support of an NGEE Arctic publication available at doi:10.5194/tc-10-341-2016. This dataset contains an ensemble of thermal-hydro soil parameters including porosity, thermal conductivity, thermal conductivity shape parameters, and residual saturation of peat and mineral soil. The ensemble was generated using a Null-Space Monte Carlo analysis of parameter uncertainty based on a calibration to soil temperatures collected at the Barrow Environmental Observatory site by the NGEE team. The micro-topography of ice wedge polygons present at the site is included in the analysis using three 1D column models to represent polygon center, rim and trough features. The Arctic Terrestrial Simulator (ATS) was used in the calibration to model multiphase thermal and hydrological processes in the subsurface.

Quantifying Arctic Terrestrial Environment Behaviors Using Geophysical, Point-Scale and Remote Sensing Data

NASA Astrophysics Data System (ADS)

Dafflon, B.; Hubbard, S. S.; Ulrich, C.; Peterson, J. E.; Wu, Y.; Wainwright, H. M.; Gangodagamage, C.; Kholodov, A. L.; Kneafsey, T. J.

2013-12-01

Improvement in parameterizing Arctic process-rich terrestrial models to simulate feedbacks to a changing climate requires advances in estimating the spatiotemporal variations in active layer and permafrost properties - in sufficiently high resolution yet over modeling-relevant scales. As part of the DOE Next-Generation Ecosystem Experiments (NGEE-Arctic), we are developing advanced strategies for imaging the subsurface and for investigating land and subsurface co-variability and dynamics. Our studies include acquisition and integration of various measurements, including point-based, surface-based geophysical, and remote sensing datasets These data have been collected during a series of campaigns at the NGEE Barrow, AK site along transects that traverse a range of hydrological and geomorphological conditions, including low- to high- centered polygons and drained thaw lake basins. In this study, we describe the use of galvanic-coupled electrical resistance tomography (ERT), capacitively-coupled resistivity (CCR) , permafrost cores, above-ground orthophotography, and digital elevation model (DEM) to (1) explore complementary nature and trade-offs between characterization resolution, spatial extent and accuracy of different datasets; (2) develop inversion approaches to quantify permafrost characteristics (such as ice content, ice wedge frequency, and presence of unfrozen deep layer) and (3) identify correspondences between permafrost and land surface properties (such as water inundation, topography, and vegetation). In terms of methods, we developed a 1D-based direct search approach to estimate electrical conductivity distribution while allowing exploration of multiple solutions and prior information in a flexible way. Application of the method to the Barrow datasets reveals the relative information content of each dataset for characterizing permafrost properties, which shows features variability from below one meter length scales to large trends over more than a kilometer. Further, we used Pole- and Kite-based low-altitude aerial photography with inferred DEM, as well as DEM from LiDAR dataset, to quantify land-surface properties and their co-variability with the subsurface properties. Comparison of the above- and below-ground characterization information indicate that while some permafrost characteristics correspond with changes in hydrogeomorphological expressions, others features show more complex linkages with landscape properties. Overall, our results indicate that remote sensing data, point-scale measurements and surface geophysical measurements enable the identification of regional zones having similar relations between subsurface and land surface properties. Identification of such zonation and associated permafrost-land surface properties can be used to guide investigations of carbon cycling processes and for model parameterization.

Effects of Spatial N nutrient mobility relevant to plants, soils and microtopograhy on plant growth and soil organic matter accumulation by using coupled CLM-PFLOTRAN biogeochemical model in an Area in NGEE-Arctic Intensive Study Sites, Barrow, AK.

NASA Astrophysics Data System (ADS)

Yuan, F.; Thornton, P. E.; Tang, G.; Xu, X.; Kumar, J.; Iversen, C. M.; Bisht, G.; Hammond, G. E.; Mills, R. T.; Wullschleger, S. D.

2015-12-01

At fine-scale spatially-explicit reactive-transport (RT) and hydrological coupled modeling for likely soil nutrient N transport mechanisms driven by gradients, soil properties and micro-topography is critical to spatial distribution of plants and thus soil organic matter stocks accumulation or changes. In this study we successfully carried out a fully coupled fine-scale CLM-PFLOTRAN soil biogeochemical (BGC) RT model simulation on Titan at 2.5mx2.5m resolution for the Area C of 100mx100m in the NGEE-Arctic Intensive Study Sites, Barrow, AK. The Area spatially varies in terms of plant function types (PFT) and soil thermal-hydraulic properties associated with locally polygonal landscape features. The spatially explicit CLM-PFLOTRAN coupled RT model allows soil N nutrient mobility driven either by diffusion or by advection or both. The modeling experiments are conducted with three soil nutrient N (NH4+ and NO3-) mobility mechanisms within the CLM-PFLOTAN: no transport, diffusion only, and diffusion and advection in 3-D soils. It shows that CLM-PFLOTRAN model simulated higher SOM C density in both lower troughs and neighbored areas when transport mechanism allowed, compared to no-transport, although with similar ranges (about 0.1~20 kgC m-3). It also simulates slightly higher LAI (0.16~0.84 vs. 0.11~0.85) in growing season, especially in lower troughs and neighbored regions. It's likely because CLM-PFLOTRAN can explicitly simulate transport of nutrients and others both vertically and laterally. So it can more mechanically mimic plant root N extract caused relatively low concentration in root zone and thus allow transport from surrounding high N concentration regions. The lateral mobility also implies that N nutrient can transport from initially high-production columns to the neighbored low-production area where then production could be improved. The results suggest that taking account of locally mobility of soil N nutrients may be critical to plant growth and thus long-term soil organic carbon stocks in this polygonal coastal tundra ecosystem at fine scale. It also implies that regional or global scale modelings should consider vertical transport (2D) due to shallow soil root zones, for which a feature in CLM-PFLOTRAN is available as well.

FRAMES Metadata Reporting Templates for Ecohydrological Observations, version 1.1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Christianson, Danielle; Varadharajan, Charuleka; Christoffersen, Brad

FRAMES is a a set of Excel metadata files and package-level descriptive metadata that are designed to facilitate and improve capture of desired metadata for ecohydrological observations. The metadata are bundled with data files into a data package and submitted to a data repository (e.g. the NGEE Tropics Data Repository) via a web form. FRAMES standardizes reporting of diverse ecohydrological and biogeochemical data for synthesis across a range of spatiotemporal scales and incorporates many best data science practices. This version of FRAMES supports observations for primarily automated measurements collected by permanently located sensors, including sap flow (tree water use), leafmore » surface temperature, soil water content, dendrometry (stem diameter growth increment), and solar radiation. Version 1.1 extend the controlled vocabulary and incorporates functionality to facilitate programmatic use of data and FRAMES metadata (R code available at NGEE Tropics Data Repository).« less

Nitrate and Moisture Content of Broad Permafrost Landscape Features in the Barrow Peninsula: Predicting Evolving NO3 Concentrations in a Changing Arctic

NASA Astrophysics Data System (ADS)

Arendt, C. A.; Heikoop, J. M.; Newman, B. D.; Wales, N. A.; McCaully, R. E.; Wilson, C. J.; Wullschleger, S.

2017-12-01

The geochemical evolution of Arctic regions as permafrost degrades, significantly impacts nutrient availability. The release of nitrogen compounds from permafrost degradation fertilizes both microbial decomposition and plant productivity. Arctic warming promotes permafrost degradation, causing geomorphic and hydrologic transitions that have the potential to convert saturated zones to unsaturated zones and subsequently alter the nitrate production capacity of permafrost regions. Changes in Nitrate (NO3-) content associated with shifting moisture regimes are a primary factor determining Arctic fertilization and subsequent primary productivity, and have direct feedbacks to carbon cycling. We have documented a broad survey of co-located soil moisture and nitrate concentration measurements in shallow active layer regions across a variety of topographic features in the expansive continuous permafrost region encompassing the Barrow Peninsula of Alaska. Topographic features of interest are slightly higher relative to surrounding landscapes with drier soils and elevated nitrate, including the rims of low centered polygons, the centers of flat and high centered polygons, the rims of young, old and ancient drain thaw lake basins and drainage slopes that exist across the landscape. With this information, we model the nitrate inventory of the Barrow Peninsula using multiple geospatial approaches to estimate total area cover by unsaturated features of interest and further predict how various drying scenarios increase the magnitude of nitrate produced in degrading permafrost regions across the Arctic. This work is supported by the US Department of Energy Next Generation Ecosystem Experiment, NGEE-Arctic.

Identifying Factors Causing Variability in Greenhouse Gas (GHG) Fluxes in a Polygonal Tundra Landscape

NASA Astrophysics Data System (ADS)

Arora, B.; Wainwright, H. M.; Vaughn, L. S.; Curtis, J. B.; Torn, M. S.; Dafflon, B.; Hubbard, S. S.

2017-12-01

Greenhouse gas (GHG) flux variations in Arctic tundra environments are important to understand because of the vast amount of soil carbon stored in these regions and the potential of these regions to convert from a global carbon sink to a source under warmer conditions. Multiple factors potentially contribute to GHG flux variations observed in these environments, including snowmelt timing, growing season length, active layer thickness, water table variations, and temperature fluctuations. The objectives of this study are to investigate temporal variability in CO2 and CH4 fluxes at Barrow, AK over three successive growing seasons (2012-14) and to determine the factors influencing this variability using a novel entropy-based classification scheme. We analyzed soil, vegetation, and climate parameters as well as GHG fluxes at multiple locations within low-, flat- and high-centered polygons at Barrow, AK as part of the Next Generation Ecosystem Experiment (NGEE) Arctic project. Entropy results indicate that different environmental factors govern variability in GHG fluxes under different spatiotemporal settings. In particular, flat-centered polygons are more likely to become significant sources of CO2 during warm and dry years as opposed to high-centered polygons that contribute considerably to CO2 emissions during cold and wet years. In contrast, the highest CH4 emissions were always associated with low-centered polygons. Temporal variability in CO2 fluxes was primarily associated with factors affecting soil temperature and/or vegetation dynamics during early and late season periods. Temporal variability in CH4 fluxes was primarily associated with changes in vegetation cover and its covariability with primary controls such as seasonal thaw—rather than direct response to changes in soil moisture. Overall, entropy results document which factors became important under different spatiotemporal settings, thus providing clues concerning the manner in which ecosystem properties may be altered regionally in a future climate.

Acid-Base Titration Curves of Soils from a Low-Centered Polygon, Barrow, Alaska, 2013

DOE Data Explorer

Jianqiu Zheng; David Graham

2017-12-05

This dataset provides pH titration data of soils from a low-centered polygon center. The soil core was collected in 2013 from a low-centered polygon center from the NGEE-Arctic Intensive Study Site 1, Barrow, Alaska.

NGEE Arctic Leaf Spectral Reflectance and Transmittance, Barrow, Alaska, 2014-2016

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shawn Serbin; Wil Lieberman-Cribbin; Kim Ely

Measurements of full-spectrum (i.e. 350-2500nm) leaf spectral reflectance of Arctic plant species. Data were collected to characterize the leaf-level optical properties and albedo of dominant Arctic tundra species in the Barrow, AK area and to enable trait scaling.

AmeriFlux Site and Data Exploration System

NASA Astrophysics Data System (ADS)

Krassovski, M.; Boden, T.; Yang, B.; Jackson, B.

2011-12-01

The AmeriFlux network was established in 1996. The network provides continuous observations of ecosystem-level exchanges of CO2, water, energy and momentum spanning diurnal, synoptic, seasonal, and interannual time scales. The current network, including both active and inactive sites, consists of 141 sites in North, Central, and South America. The Carbon Dioxide Information Analysis Center (CDIAC) at Oak Ridge National Laboratory (ORNL) provides data management support for the AmeriFlux network including long-term data storage and dissemination. AmeriFlux offers a broad suite of value-added data products: Level 1 data products at 30 minute or hourly time intervals provided by the site teams, Level 2 data processed by CDIAC and Level 3 and 4 files created using CarboEurope algorithms. CDIAC has developed a relational database to house the vast array of AmeriFlux data and information and a web-based interface to the database, the AmeriFlux Site and Data Exploration System (http://ameriflux.ornl.gov), to help users worldwide identify, and more recently, download desired AmeriFlux data. AmeriFlux and CDIAC offer numerous value-added AmeriFlux data products (i.e., Level 1-4 data products, biological data) and most of these data products are or will be available through the new data system. Vital site information (e.g., location coordinates, dominant species, land-use history) is also displayed in the new system. The data system provides numerous ways to explore and extract data. Searches can be done by site, location, measurement status, available data products, vegetation types, and by reported measurements just to name a few. Data can be accessed through the links to full data sets reported by a site, organized by types of data products, or by creating customized datasets based on user search criteria. The new AmeriFlux download module contains features intended to ease compliance of the AmeriFlux fair-use data policy, acknowledge the contributions of submitting investigators, inform AmeriFlux investigators of users of their data, and facilitate meaningful usage statistics. Comprehensive site descriptions are available via the same interface along with site-related publications and data visualization functionality. This presentation reflects the present state and functionality of the AmeriFlux Site and Data Exploration System as well as future plans for expansion. For example, future plans call for expansion of the relational database to house similar data from large-scale ecosystem experiments (e.g., FACE, NGEE - Next Generation Ecosystem Experiment) and inclusion of enhanced query capabilities (e.g., sorting data via day and night).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bryan Curtis; Margaret Torn

Data generated from an observational platform (Tram) consisting of 68 meters of elevated track 1 to 1.5 meters above the surface and an automated cart carrying a suite of radiation and remote sensing instruments (see below table). The Tram is in the footprint of NGEE Arctic/AmeriFlux tower at the Barrow Environmental Observatory, Barrow, Alaska.

Federal Data Repository Research: Recent Developments in Mercury Search System Architecture

NASA Astrophysics Data System (ADS)

Devarakonda, R.

2015-12-01

New data intensive project initiatives needs new generation data system architecture. This presentation will discuss the recent developments in Mercury System [1] including adoption, challenges, and future efforts to handle such data intensive projects. Mercury is a combination of three main tools (i) Data/Metadata registration Tool (Online Metadata Editor): The new Online Metadata Editor (OME) is a web-based tool to help document the scientific data in a well-structured, popular scientific metadata formats. (ii) Search and Visualization Tool: Provides a single portal to information contained in disparate data management systems. It facilitates distributed metadata management, data discovery, and various visuzalization capabilities. (iii) Data Citation Tool: In collaboration with Department of Energy's Oak Ridge National Laboratory (ORNL) Mercury Consortium (funded by NASA, USGS and DOE), established a Digital Object Identifier (DOI) service. Mercury is a open source system, developed and managed at Oak Ridge National Laboratory and is currently being funded by three federal agencies, including NASA, USGS and DOE. It provides access to millions of bio-geo-chemical and ecological data; 30,000 scientists use it each month. Some recent data intensive projects that are using Mercury tool: USGS Science Data Catalog (http://data.usgs.gov/), Next-Generation Ecosystem Experiments (http://ngee-arctic.ornl.gov/), Carbon Dioxide Information Analysis Center (http://cdiac.ornl.gov/), Oak Ridge National Laboratory - Distributed Active Archive Center (http://daac.ornl.gov), SoilSCAPE (http://mercury.ornl.gov/soilscape). References: [1] Devarakonda, Ranjeet, et al. "Mercury: reusable metadata management, data discovery and access system." Earth Science Informatics 3.1-2 (2010): 87-94.

NGEE Arctic Plant Traits: Soil Depth, Kougarok Road Mile Marker 64, Seward Peninsula, Alaska, Beginning 2016

DOE Data Explorer

Stel, Holly Vander; Wullschleger, Stan; Breen, Amy; Iversen, Colleen

2017-03-01

Data includes active layer depth measured at intensive plots, reference points, vegetation plots, and soil temperature/moisture monitoring stations at the Kougarok hill slope located at Kougarok Road, Mile Marker 64. Data collection started July 2016 and will be ongoing. Data upload will be completed January 2017.

NGEE Arctic Plant Traits: Soil Nutrient Availability, Kougarok Road Mile Marker 64, Seward Peninsula, Alaska, beginning 2016

DOE Office of Scientific and Technical Information (OSTI.GOV)

Verity Salmon; Colleen Iversen; Amy Breen

Soil nutrient availability at all vegetation plots was measured using anion and cation binding resins deployed to vegetation plots at the Kougarok hillslope site located at Kougarok Road Marker 64. Concentrations of ammonia, nitrate, and phosphate in resin extract solutions were determined in the lab.

CO2 and CH4 Production in Low-Temperature Soil Incubations from Low and High Centered Polygons, Barrow, Alaska, 2012-2013

DOE Data Explorer

Taniya RoyChowdhury; David Graham; Stan Wullschleger

2016-08-29

The dataset consists of respiration and methane production rates obtained from soil microcosm studies carried out under controlled temperature and incubation conditions. Soils represent the low- and high-centered polygon active layers and permafrost (when present) from the NGEE-Arctic Intensive Study Site 1.

NGEE Arctic Plant Traits: Vegetation Plot Locations, Ecotypes, and Photos, Kougarok Road Mile Marker 64, Seward Peninsula, Alaska, 2016

DOE Office of Scientific and Technical Information (OSTI.GOV)

Colleen Iversen; Amy Breen; Verity Salmon

Data includes GPS waypoints for intensive plots, reference points, vegetation plots, and soil temperature/moisture monitoring stations that were established in July 2016 at the Kougarok hill slope located at Kougarok Road, Mile Marker 64. Photographs of all intensive plots and reference points are also included.

Soil Organic Carbon Degradation in Low Temperature Soil Incubations from Flat- and High-Centered Polygons, Barrow, Alaska, 2012-2013

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jianqiu Zheng; David Graham

This dataset provides information about organic acids accumulation and ferrous ion concentrations during soil incubations at controlled temperature. Soil cores were collected in 2012 and 2013 from the flat- and high-centered polygon active layers and permafrost (when present) from the NGEE-Arctic Intensive Study Site 1, Barrow, Alaska.

Leaf Mass Area, Leaf Carbon and Nitrogen Content, Kougarok Road and Teller Road, Seward Peninsula, Alaska, 2016

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shawn Serbin; Alistair Rogers; Kim Ely

Carbon, Nitrogen and Leaf Mass Area of leaves sampled from locations on the Kougarok Rd (transect A) and Teller Rd NGEE Arctic study sites, Seward Peninsula, Alaska. Species include: Alnus viridis spp. fruticosa, Arctostaphylos rubra, Betula glandulosa, Chamerion latifolium, Petasites frigidus, Salix alaxensis, Salix glauca, Salix pulchra, Salix richardsonii and Vaccinium uliginosum.

NGEE Arctic Tram: Photographs over Low- and High-Centered Polygon Vegetation Communities, Barrow, Alaska, 2014-2017

DOE Data Explorer

J. Bryan Curtis; Margaret Torn

2017-10-05

This dataset provides a digital image of each measurement position stop for every run of the Tram. There are 137 stops per run and there were sometimes multiple runs per day. This first version provides 12,714 images (*.jpg) collected over 28 days in 2015. Images for the other years will be added.

Management and assimilation of diverse, distributed watershed datasets

NASA Astrophysics Data System (ADS)

Varadharajan, C.; Faybishenko, B.; Versteeg, R.; Agarwal, D.; Hubbard, S. S.; Hendrix, V.

2016-12-01

The U.S. Department of Energy's (DOE) Watershed Function Scientific Focus Area (SFA) seeks to determine how perturbations to mountainous watersheds (e.g., floods, drought, early snowmelt) impact the downstream delivery of water, nutrients, carbon, and metals over seasonal to decadal timescales. We are building a software platform that enables integration of diverse and disparate field, laboratory, and simulation datasets, of various types including hydrological, geological, meteorological, geophysical, geochemical, ecological and genomic datasets across a range of spatial and temporal scales within the Rifle floodplain and the East River watershed, Colorado. We are using agile data management and assimilation approaches, to enable web-based integration of heterogeneous, multi-scale dataSensor-based observations of water-level, vadose zone and groundwater temperature, water quality, meteorology as well as biogeochemical analyses of soil and groundwater samples have been curated and archived in federated databases. Quality Assurance and Quality Control (QA/QC) are performed on priority datasets needed for on-going scientific analyses, and hydrological and geochemical modeling. Automated QA/QC methods are used to identify and flag issues in the datasets. Data integration is achieved via a brokering service that dynamically integrates data from distributed databases via web services, based on user queries. The integrated results are presented to users in a portal that enables intuitive search, interactive visualization and download of integrated datasets. The concepts, approaches and codes being used are shared across various data science components of various large DOE-funded projects such as the Watershed Function SFA, Next Generation Ecosystem Experiment (NGEE) Tropics, Ameriflux/FLUXNET, and Advanced Simulation Capability for Environmental Management (ASCEM), and together contribute towards DOE's cyberinfrastructure for data management and model-data integration.

NGEE Arctic Plant Traits: Soil Temperature and Moisture, Kougarok Road Mile Marker 64, Seward Peninsula, Alaska, beginning 2016

DOE Data Explorer

Colleen Iversen; Verity Salmon; Amy Breen; Holly Vander Stel; Stan Wullschleger

2017-03-10

Data includes soil temperature and soil moisture measured at the Kougarok hill slope located at Kougarok Road, Mile Marker 64. Most measurements are from monitoring stations with permanently installed probes though the data also includes single point measurements from handheld devices. Data collection began in July 2016 and is ongoing. Data upload will be completed March 2017.

CO2 and CH4 Production and CH4 Oxidation in Low Temperature Soil Incubations from Flat- and High-Centered Polygons, Barrow, Alaska, 2012

DOE Data Explorer

David E. Graham; Jianqiu Zheng; Taniya RoyChowdhury

2016-08-31

The dataset consists of respiration and methane production rates and methane oxidation potential obtained from soil microcosm studies carried out under controlled temperature and incubation conditions. Soils cores collected in 2012 represent the flat- and high-centered polygon active layers and permafrost (when present) from the NGEE Arctic Intensive Study Site 1, Barrow, Alaska.

NGEE Arctic Plant Traits: Plant Biomass and Traits, Kougarok Road Mile Marker 64, Seward Peninsula, Alaska, beginning 2016

DOE Office of Scientific and Technical Information (OSTI.GOV)

Verity Salmon; Colleen Iversen; Amy Breen

Data includes aboveground biomass and plant traits for destructive harvests performed at the Kougarok hill slope located at Kougarok Road, Mile Marker 64. Data collection began in July 2016. Aboveground biomass and aboveground plant traits are available for shrub and understory species found in vegetation plots. Paired observations of aboveground and belowground plant traits are available for select shrub species.

Ground Water Levels for NGEE Areas A, B, C and D, Barrow, Alaska, 2012-2014

DOE Data Explorer

Anna Liljedahl; Cathy Wilson

2015-06-08

Ice wedge polygonal tundra water levels were measured at a total of 45 locations representing polygon centers and troughs during three summers. Early season water levels, which were still affected by ice and snow, are represented by manual measurements only. Continuous (less than hourly) measurements followed through early fall (around mid-Sep). The data set contains inundation depth (cm), absolute water level and local ground surface elevation (masl).

NGEE Arctic Canopy Spectral Reflectance, Barrow, Alaska, 2014-2016

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shawn Serbin; Wil Lieberman-Cribbin; Kim Ely

Measurements of full-spectrum (i.e. 350-2500nm) canopy spectral reflectance of Arctic plant species within the BEO, Barrow, Alaska. Spectra were collected using an Spectra Vista Corporation (SVC) HR-2014i and Spectral Evolution (SE) PSR+ instrument mounted on a tripod or monopod together with a Spectralon white plate to calibrate each measurement under variable illumination conditions. Data were collected in Barrow, Alaska during the 2014 to 2016 period.

Mapping Deep Low Velocity Zones in Alaskan Arctic Coastal Permafrost using Seismic Surface Waves

NASA Astrophysics Data System (ADS)

Dou, S.; Ajo Franklin, J. B.; Dreger, D. S.

2012-12-01

Permafrost degradation may be an important amplifier of climate change; Thawing of near-surface sediments holds the potential of increasing greenhouse gas emissions due to microbial decomposition of preserved organic carbon. Recently, the characterization of "deep" carbon pools (several meters below the surface) in circumpolar frozen ground has increased the estimated amount of soil carbon to three times higher than what was previously thought. It is therefore potentially important to include the characteristics and processes of deeper permafrost strata (on the orders of a few to tens of meters below surface) in climate models for improving future predictions of accessible carbon and climate feedbacks. This extension is particularly relevant if deeper formations are not completely frozen and may harbor on-going microbial activity despite sub-zero temperatures. Unfortunately, the characterization of deep permafrost systems is non-trivial; logistics and drilling constraints often limit direct characterization to relatively shallow units. Geophysical measurements, either surface or airborne, are often the most effective tools for evaluating these regions. Of the available geophysical techniques, the analysis of seismic surface waves (e.g. MASW) has several unique advantages, mainly the ability to provide field-scale information with good depth resolution as well as penetration (10s to 100s of m with small portable sources). Surface wave methods are also able to resolve low velocity regions, a class of features that is difficult to characterize using traditional P-wave refraction methods. As part of the Department of Energy (DOE) Next-Generation Ecosystem Experiments (NGEE-Arctic) project, we conducted a three-day seismic field survey (May 12 - 14, 2012) at the Barrow Environmental Observatory, which is located within the Alaskan Arctic Coastal Plain. Even though permafrost at the study site is continuous, ice-rich and thick (>= 350m), our Multichannel Analysis of Surface Waves (MASW) suggests the existence of pronounced low shear wave velocity zones that span the depth range of 2 - 30 meters; this zone has shear velocity values comparable to partially thawed soils. Such features coincide with previous findings of very low electrical resistivity structure (as low as ~10 Ohm*m at some locations) from measurements obtained in the first NGEE-Arctic geophysical field campaign (conducted in the week of September 24 - October 1, 2011). These low shear velocity zones are likely representative of regions with high unfrozen water content and thus have important implications on the rate of microbial activity and the vulnerability of deep permafrost carbon pools. Analysis of this dataset required development of a novel inversion approach based on waveform inversion. The existence of multiple closely spaced Rayleigh wave modes made traditional inversion based on mode picking virtually impossible; As a result, we selected a direct misfit evaluation based on comparing dispersion images in the phase velocity/frequency domain. The misfit function was optimized using a global search algorithm, in this case Huyer and Neumaier's Multi Coordinate Search algorithm (MCS). This combination of MCS and waveform misfit allowed recovery of the low velocity region despite the existence of closely spaced modes.

Mosaicked Historic Airborne Imagery from Seward Peninsula, Alaska, Starting in the 1950's

DOE Data Explorer

Cherry, Jessica; Wirth, Lisa

2016-12-06

Historical airborne imagery for each Seward Peninsula NGEE Arctic site - Teller, Kougarok, Council - with multiple years for each site. This dataset includes mosaicked, geolocated and, where possible, orthorectified, historic airborne and recent satellite imagery. The older photos were sourced from USGS's Earth Explorer site and the newer, satellite imagery is from the Statewide Digital Mapping Initiative (SDMI) project managed by the Geographic Information Network of Alaska on behalf of the state of Alaska.

The Arctic Boreal Vulnerability Experiment (ABoVE) 2017 Airborne Campaign

NASA Astrophysics Data System (ADS)

Miller, C. E.; Goetz, S. J.; Griffith, P. C.; Hoy, E.; Larson, E. K.; Hodkinson, D. J.; Hansen, C.; Woods, J.; Kasischke, E. S.; Margolis, H. A.

2017-12-01

The 2017 ABoVE Airborne Campaign (AAC) was one of the largest airborne experiments ever conducted by NASA's Earth Science Division. It involved nine aircraft in 17 deployments - more than 100 flights - between April and October and sampled over 4 million km2in Alaska and northwestern Canada. Many of these flights were coordinated with detailed, same-day ground-based measurements to link field-based, process-level studies with geospatial data products derived from satellite remote sensing. A major goal of the 2017 AAC was to collect data that spanned the critical intermediate space and time scales that are essential for a comprehensive understanding of scaling issues across the ABoVE Study Domain and extrapolation to the pan-Arctic. Additionally, the 2017 AAC provided unique opportunities to validate satellite and airborne remote sensing data for northern high latitude ecosystems, develop and advance fundamental remote sensing science, and explore scientific insights from innovative sensor combinations. The 2017 AAC science strategy coupled domain-wide sampling with L-band and P-band synthetic aperture radar (SAR), imaging spectroscopy (AVIRIS-NG), full waveform lidar (LVIS) and atmospheric carbon dioxide and methane with more spatially and temporally focused studies using Ka-band SAR (Ka-SPAR) and solar induced chlorophyll fluorescence (CFIS). Additional measurements were coordinated with the NEON Airborne Observing Platform, the ASCENDS instrument development suite, and the ATOM EV-S2 investigation. Targets of interest included the array of field sites operated by the ABoVE Science Team as well as the intensive sites operated by the DOE NGEE-Arctic team on the Seward Peninsula and in Barrow, NSF's LTER sites at Toolik Lake (North Slope) and Bonanza Creek (Interior Alaska), the Canadian Cold Regions Hydrology sites in the Arctic tundra near Trail Valley Creek NT, the Government of the Northwest Territories Slave River/Slave Delta watershed time series and numerous forest and fire disturbance plots maintained by the Alaskan and Canadian Forestry Services. We will present an overview of the 2017 AAC and highlight some key preliminary results.

NGEE Arctic Plant Traits: Shrub Transects, Kougarok Road Mile Marker 64, Seward Peninsula, Alaska, 2016

DOE Data Explorer

Verity Salmon; Colleen Iversen; Peter Thornton; Ma

2017-03-01

Transect data is from point center quarter surveys for shrub density performed in July 2016 at the Kougarok hill slope located at Kougarok Road, Mile Marker 64. For each sample point along the transects, moving averages for shrub density and shrub basal area are provided along with GPS coordinates, average shrub height and active layer depth. The individual height, basal area, and species of surveyed shrubs are also included. Data upload will be completed January 2017.

Chemical and Isotopic Characterization of Surface Water and Active Layer Pore Water in a Tundra Landscape, Barrow, Alaska, USA

NASA Astrophysics Data System (ADS)

Newman, B. D.; Heikoop, J. M.; Throckmorton, H.; Arendt, C. A.; Graham, D. E.; Wilson, C. J.; Wullschleger, S. D.

2016-12-01

Studies conducted in the Barrow Environmental Observatory as part of the Next Generation Ecosystem Experiment (NGEE) - Arctic have demonstrated significant chemical and isotopic variability in surface water and active layer pore water of polygonal terrain located between drained thaw lake basins (DTLBs). In this study, we report on chemical and isotopic variation at the broader landscape scale that includes different age DTLBs and associated drainages, extant thaw lakes, and interlake regions. Fingerprint diagrams of major elements show a broader range of variation at the landscape scale relative to polygonal terrain. ANOVA analysis suggests that many of the polygonal and broader landscape scale sites have similar chemistry, suggesting a reasonably high degree of hydrologic connectivity. The most significant site-specific differences include higher d18O and d2H, indicative of evaporative conditions, of surface and active layer water from an ancient (2000- 5500 BP) DTLB that comprises a shallow basin with no outlets. Significantly higher Cl, Ca, Fe, Mg, Na, As, Mn and Sr concentrations were also found in pore waters collected immediately above the frost table at two locations. The first location is a small drainage leading from an area of polygonal terrain into an adjacent slough, while the second is upgradient of the estuarine terminus of a drainage sourced from a medium-aged DTLB (50- 300 BP). Higher concentrations at the frost table suggests a mechanism related to periodic freezing and thawing of the transition zone above permafrost or permafrost degradation. Alternative conceptual models, including the presence of a marine signal or the influence of cryopegs (brine layers within permafrost), will also be considered. Characterization of present day Arctic hydrology and chemistry at different scales is important for Earth Systems Models and for predicting hydrogeochemical change associated with landscape evolution due to future permafrost degradation.

NGEE Arctic Zero Power Warming PhenoCamera Images, Barrow, Alaska, 2016

DOE Data Explorer

Shawn Serbin; Andrew McMahon; Keith Lewin; Kim Ely; Alistair Rogers

2016-11-14

StarDot NetCam SC pheno camera images collected from the top of the Barrow, BEO Sled Shed. The camera was installed to monitor the BNL TEST group's prototype ZPW (Zero Power Warming) chambers during the growing season of 2016 (including early spring and late fall). Images were uploaded to the BNL FTP server every 10 minutes and renamed with the date and time of the image. See associated data "Zero Power Warming (ZPW) Chamber Prototype Measurements, Barrow, Alaska, 2016" http://dx.doi.org/10.5440/1343066.

Synthesis of soil geochemical characteristics and organic carbon degradation in Arctic polygon tundra, Barrow, Alaska

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zheng, Jianqiu; RoyChowdhury, Taniya; Herndon, Elizabeth

This is a synthesis data product that reports (1) the results of soil geochemical characterization and (2) organic carbon degradation in low temperature soil incubations on cores collected on the NGEE Arctic Study Area near Utqiaġvik (Barrow), Alaska. The study area consists of thaw lakes, drained thaw lake basins and interstitial tundra with a polygonal landscape of microtopographic features created by ice wedges. Integrated geochemical and organic carbon degradation data from 9 individual soil cores are included in the synthesis product.

Factors Impacting Spatial Patterns of Snow Distribution in a Small Catchment near Nome, AK

NASA Astrophysics Data System (ADS)

Chen, M.; Wilson, C. J.; Charsley-Groffman, L.; Busey, R.; Bolton, W. R.

2017-12-01

Snow cover plays an important role in the climate, hydrology and ecological systems of the Arctic due to its influence on the water balance, thermal regimes, vegetation and carbon flux. Thus, snow depth and coverage have been key components in all the earth system models but are often poorly represented for arctic regions, where fine scale snow distribution data is sparse. The snow data currently used in the models is at coarse resolution, which in turn leads to high uncertainty in model predictions. Through the DOE Office of Science Next Generation Ecosystem Experiment, NGEE-Arctic, high resolution snow distribution data is being developed and applied in catchment scale models to ultimately improve representation of snow and its interactions with other model components in the earth system models . To improve these models, it is important to identify key factors that control snow distribution and quantify the impacts of those factors on snow distribution. In this study, two intensive snow depth surveys (1 to 10 meters scale) were conducted for a 2.3 km2 catchment on the Teller road, near Nome, AK in the winter of 2016 and 2017. We used a statistical model to quantify the impacts of vegetation types, macro-topography, micro-topography, and meteorological parameters on measured snow depth. The results show that snow spatial distribution was similar between 2016 and 2017, snow depth was spatially auto correlated over small distance (2-5 meters), but not spatially auto correlated over larger distance (more than 2-5 meters). The coefficients of variation of snow depth was above 0.3 for all the snow survey transects (500-800 meters long). Variation of snow depth is governed by vegetation height, aspect, slope, surface curvature, elevation and wind speed and direction. We expect that this empirical statistical model can be used to estimate end of winter snow depth for the whole watershed and will further develop the model using data from other arctic regions to estimate seasonally dynamic snow coverage and properties for use in catchment scale to pan-Arctic models.

Seasonal and Downslope Changes in the Pore Water Geochemistry of Tundra Soils Near Nome, Alaska

NASA Astrophysics Data System (ADS)

Philben, M. J.; Zheng, J.; Wullschleger, S. D.; Graham, D. E.; Gu, B.

2017-12-01

Thawing permafrost is exposing vast stores of organic matter to decomposition in previously frozen tundra soils. In low-relief and poorly drained areas, the complexity of microbial metabolism under anaerobic conditions complicates the prediction of resulting CO2 and CH4 emissions. To improve this understanding, we investigated the dissolved gas and major ion concentrations and DOM composition in depth profiles of soil pore water collected from the Teller Road site near Nome, AK, as part of the Next Generation Ecosystem Experiment (NGEE)-Arctic. Pathways of anaerobic organic matter degradation were inferred based on two complementary approaches: first, we compared the composition of soil pore waters of saturated areas in the peat plateau and the base of the hillslope, collected early and late in the thaw season (July and September) to assess seasonal changes in the soil solution chemistry. CH4 and low molecular weight organic acids (e.g., acetate, formate, and propionate) were both near or below the detection limit in July but accumulated later in the season. In contrast, SO42- and Fe(III) concentrations were high in July and low in September, while Fe(II) was higher in September. These results suggest SO42- and Fe(III) reduction were the primary pathways for anaerobic respiration early in the thaw season, while methanogenesis increased in September as labile organic acids accumulated. Second, we assessed the change in DOM composition in a transect of piezometers, capturing the degradation of organic matter during transport down a hillslope. The DOC concentration did not change, but SUVA254 declined and the organic acid concentration increased downslope. In addition, Fourier-transform infrared spectroscopy indicated the ratio of carboxyl to amide and aromatic functional groups increased downslope. These parameters show that although there was no net loss of DOC along the transect, it was transformed to less aromatic and potentially more labile forms. Together, these results suggest that the depletion of electron acceptors in anoxic pore waters over the course of the thaw season leads to accumulation of labile C compounds, which are likely vulnerable to decomposition following thaw or disturbance.

Physical, Chemical, and Hydrologic Characteristics of Active Layer and Permafrost Soils of Arctic Polygonal Tundra, Barrow, Alaska, 2013-2016

DOE Data Explorer

Yuxin Wu; Craig Ulrich; Tim Kneafsey

2018-03-22

This dataset reports the results of physical, chemical, and hydrologic analyses of soil cores collected at the NGEE Arctic Intensive Sites 0 and 1 (Plots A, B, C, and D) during late winter seasons (April-May) from 2013 to 2016. Locations were selected across the polygonal ground to include low, flat, and high centered polygons (LCPs, FCPs and HCPs) and internal features (i.e. the trough, center, and rim). The data are depth-resolved and down to ~ 4m below ground surface for some cores. The specific depths for each core where samples were analyzed vary from core to core.

A Conceptual Framework to Enhance the Interoperability of Observatories among Countries, Continents and the World

NASA Astrophysics Data System (ADS)

Loescher, H.; Fundamental Instrument Unit

2013-05-01

Ecological research addresses challenges relating to the dynamics of the planet, such as changes in climate, biodiversity, ecosystem functioning and services, carbon and energy cycles, natural and human-induced hazards, and adaptation and mitigation strategies that involve many science and engineering disciplines and cross national boundaries. Because of the global nature of these challenges, greater international collaboration is required for knowledge sharing and technology deployment to advance earth science investigations and enhance societal benefits. For example, the Working Group on Biodiversity Preservation and Ecosystem Services (PCAST 2011) noted the scale and complexity of the physical and human resources needed to address these challenges. Many of the most pressing ecological research questions require global-scale data and global scale solutions (Suresh 2012), e.g., interdisciplinary data access from data centers managing ecological resources and hazards, drought, heat islands, carbon cycle, or data used to forecast the rate of spread of invasive species or zoonotic diseases. Variability and change at one location or in one region may well result from the superposition of global processes coupled together with regional and local modes of variability. For example, we know the El Niño-Southern Oscillation large-scale modes of variability in the coupled terrestrial-aquatic-atmospheric systems' correlation with variability in regional rainfall and ecosystem functions. It is therefore a high priority of government and non-government organizations to develop the necessary large scale, world-class research infrastructures for environmental research—and the framework by which these data can be shared, discovered, and utilized by a broad user community of scientists and policymakers, alike. Given that there are many, albeit nascent, efforts to build new environmental observatories/networks globally (e.g., EU-ICOS, EU-Lifewatch, AU-TERN, China-CERN, GEOSS, GEO-BON, NutNet, etc.) and domestically, (e.g., NSF-CZO, USDA-LTAR, DOE-NGEE, Soil Carbon Network, etc.), there is a strong and mutual desire to assure interoperability of data. Developing interoperability is the degree by which each of the following is mapped between observatories (entities), defined by linking i) science requirements with science questions, ii) traceability of measurements to nationally and internationally accepted standards, iii) how data product are derived, i.e., algorithms, procedures, and methods, and iv) the bioinformatics which broadly include data formats, metadata, controlled vocabularies, and semantics. Here, we explore the rationale and focus areas for interoperability, the governance and work structures, example projects (NSF-NEON, EU-ICOS, and AU-TERN), and the emergent roles of scientists in these endeavors.

A Subgrid Approach for Modeling Microtopography Effects on Overland Flow: Application to Polygonal Tundra: Modeling Archive

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahmad Jan; Ethan Coon; Scott Painter

This Modeling Archive is in support of an NGEE Arctic manuscript under review. A new subgrid model was implemented in the Advanced Terrestrial Simulator (ATS) to capture micro-topography effects on surface flow. A comparison of the fine-scale simulations on seven individual ice-wedge polygons and a cluster of polygons was made between the results of the subgrid model and no-subgrid model. Our finding confirms that the effects of small-scale spatial heterogeneities can be captured in the coarsened models. The dataset contains meshes, inputfiles, subgrid parameters used in the simulations. Python scripts for post-processing and files for geometric analyses are also included.

Biogeochemical Controls on Microbial CO2 and CH4 Production in Polygonal Soils From the Barrow Environmental Observatory

NASA Astrophysics Data System (ADS)

Graham, D. E.; Roy Chowdhury, T.; Herndon, E.; Gu, B.; Liang, L.; Wullschleger, S. D.

2014-12-01

Organic matter buried in Arctic soils and permafrost will become accessible to increased microbial degradation as the ground warms due to climate change. The rates of organic matter degradation and the proportion of CH4 and CO2 greenhouse gasses released in a potential warming feedback cycle depend on the microbial response to warming, organic carbon structure and availability, the pore-water quantity and geochemistry, and available electron acceptors. Significant amounts of iron(II) ions in organic and mineral soils of the active layer in low-centered ice wedge polygons indicate anoxic conditions in most soil horizons. To adapt and improve the representation of these Arctic subsurface processes in terrestrial ecosystem models for the NGEE Arctic project, we examined soil organic matter transformations from elevated and subsided areas of low- and high-centered polygons from interstitial tundra on the Barrow Environmental Observatory (Barrow, AK). Using microcosm incubations at fixed temperatures and controlled thawing systems for frozen soil cores, we investigated the microbiological processes and rates of soil organic matter degradation and greenhouse gas production under anoxic conditions, at ecologically relevant temperatures of -2, +4 or +8 °C. In contrast to the low-centered polygon incubations representing in situ water-saturated conditions, microcosms with unsaturated high-centered polygon samples displayed lower carbon mineralization as either CH4 or CO2. Substantial differences in CH4 and CO2 response curves from different microtopographic samples separate the thermodynamic controls on biological activity from the kinetic controls of microbial growth and migration that together determine the temperature response for greenhouse gas emissions in a warming Arctic.

Modeling the spatio-temporal variability in subsurface thermal regimes across a low-relief polygonal tundra landscape: Modeling Archive

DOE Data Explorer

Kumar, Jitendra; Collier, Nathan; Bisht, Gautam; Mills, Richard T.; Thornton, Peter E.; Iversen, Colleen M.; Romanovsky, Vladimir

2016-01-27

This Modeling Archive is in support of an NGEE Arctic discussion paper under review and available at http://www.the-cryosphere-discuss.net/tc-2016-29/. Vast carbon stocks stored in permafrost soils of Arctic tundra are under risk of release to atmosphere under warming climate. Ice--wedge polygons in the low-gradient polygonal tundra create a complex mosaic of microtopographic features. The microtopography plays a critical role in regulating the fine scale variability in thermal and hydrological regimes in the polygonal tundra landscape underlain by continuous permafrost. Modeling of thermal regimes of this sensitive ecosystem is essential for understanding the landscape behaviour under current as well as changing climate. We present here an end-to-end effort for high resolution numerical modeling of thermal hydrology at real-world field sites, utilizing the best available data to characterize and parameterize the models. We develop approaches to model the thermal hydrology of polygonal tundra and apply them at four study sites at Barrow, Alaska spanning across low to transitional to high-centered polygon and representative of broad polygonal tundra landscape. A multi--phase subsurface thermal hydrology model (PFLOTRAN) was developed and applied to study the thermal regimes at four sites. Using high resolution LiDAR DEM, microtopographic features of the landscape were characterized and represented in the high resolution model mesh. Best available soil data from field observations and literature was utilized to represent the complex hetogeneous subsurface in the numerical model. This data collection provides the complete set of input files, forcing data sets and computational meshes for simulations using PFLOTRAN for four sites at Barrow Environmental Observatory. It also document the complete computational workflow for this modeling study to allow verification, reproducibility and follow up studies.

Addressing numerical challenges in introducing a reactive transport code into a land surface model: A biogeochemical modeling proof-of-concept with CLM-PFLOTRAN 1.0: Modeling Archive

DOE Data Explorer

Tang, G.; Andre, B.; Hoffman, F. M.; Painter, S. L.; Thornton, P. E.; Yuan, F.; Bisht, G.; Hammond, G. E.; Lichtner, P. C.; Kumar, J.; Mills, R. T.; Xu, X.

2016-04-19

This Modeling Archive is in support of an NGEE Arctic discussion paper under review and available at doi:10.5194/gmd-9-927-2016. The purpose is to document the simulations to allow verification, reproducibility, and follow-up studies. This dataset contains shell scripts to create the CLM-PFLOTRAN cases, specific input files for PFLOTRAN and CLM, outputs, and python scripts to make the figures using the outputs in the publication. Through these results, we demonstrate that CLM-PFLOTRAN can approximately reproduce CLM results in selected cases for the Arctic, temperate and tropic sites. In addition, the new framework facilitates mechanistic representations of soil biogeochemistry processes in the land surface model.

Long-term Ecosystem Experiments, Data Assimilation, and Meta-Analysis

NASA Astrophysics Data System (ADS)

Hungate, B. A.; Van Groenigen, K. J.; Osenberg, C. W.; van Gestel, N.

2015-12-01

Land ecosystems affect climate and the atmosphere, and climate and atmospheric change affects ecosystems. Syntheses of ecosystem experiments investigating their responses to environmental change holds promise for understanding how to model these interactions, and thereby gain insight into Earth's future biosphere, atmosphere, and climate. Long-term experiments examining ecosystem responses are thought to be especially important in this effort, for their potential to reveal cumulative and progressive effects, subtle effects initially undetectable experimentally, but manifest more clearly over time, often with stronger implications for modeled responses than the more dramatic, short-term experimental responses. Here, we present new analyses of long-term experiments manipulating temperature, CO2 concentration, and precipitation, testing the general hypothesis that there are common temporal patterns of responses that reveal general biogeochemical characterizing ecosystem responses to these environmental changes. For example, we show that increased carbon input with elevated CO2 stimulates emissions of nitrous oxide and methane, important greenhouse gases, and that effects show no signs of diminishing over the duration of experiments that have documented responses. At the same time, we show that the temporal resolution for this response is limited, pointing to a potential limitation in the ability of experiments to address clearly long-term hypotheses. We also show that warming tends to have limited cumulative effects on total soil carbon stocks in long-term experiments, and explore the mechanisms underlying this response. Finally, we discuss the implications of these findings for models used to simulate long-term ecosystem responses to these environmental forcings, as well as the implications of these findings for the next generation of terrestrial ecosystem experiments.

The Hardwood Ecosystem Experiment: a framework for studying responses to forest management

Treesearch

Robert K. Swihart; Michael R. Saunders; Rebecca A. Kalb; G. Scott Haulton; Charles H., eds. Michler

2013-01-01

Conditions in forested ecosystems of southern Indiana are described before initiation of silvicultural treatments for the Hardwood Ecosystem Experiment (HEE). The HEE is a 100-year study begun in 2006 in Morgan-Monroe and Yellowwood State Forests to improve the sustainability of forest resources and quality of life of Indiana residents by understanding ecosystem and...

A pre-treatment assessment of small mammals in the hardwood ecosystem experiment

Treesearch

Natasha A. Urban; Robert K. Swihart

2013-01-01

The Hardwood Ecosystem Experiment (HEE) is a 100-year, replicated experiment implemented in south-central Indiana to examine the impacts of multiple timber management regimes on forest ecosystems. A secondary objective of the HEE is to evaluate responses of small mammal assemblages. We trapped at 32 sites prior to silvicultural treatments to assess pre-treatment small...

Influences and interactions of inundation, peat, and snow on active layer thickness: Modeling Archive

DOE Data Explorer

Scott Painter; Ethan Coon; Cathy Wilson; Dylan Harp; Adam Atchley

2016-04-21

This Modeling Archive is in support of an NGEE Arctic publication currently in review [4/2016]. The Advanced Terrestrial Simulator (ATS) was used to simulate thermal hydrological conditions across varied environmental conditions for an ensemble of 1D models of Arctic permafrost. The thickness of organic soil is varied from 2 to 40cm, snow depth is varied from approximately 0 to 1.2 meters, water table depth was varied from -51cm below the soil surface to 31 cm above the soil surface. A total of 15,960 ensemble members are included. Data produced includes the third and fourth simulation year: active layer thickness, time of deepest thaw depth, temperature of the unfrozen soil, and unfrozen liquid saturation, for each ensemble member. Input files used to run the ensemble are also included.

The Glacier Lakes Ecosystem Experiments Site

Treesearch

R. C. Musselman

1994-01-01

The Glacier Lakes Ecosystem Experiment Site (GLEES), a 600 ha research watershed at 3200-3400 m elevation in the Snowy Range of SE Wyoming, has been established to examine the effects of atmospheric deposition on alpine and subalpine ecosystems. This document provides preliminary data on the landscape habitats, floristics, geology, soils, aquatics, atmospheric...

Experimenting with ecosystem interaction networks in search of threshold potentials in real-world marine ecosystems.

PubMed

Thrush, Simon F; Hewitt, Judi E; Parkes, Samantha; Lohrer, Andrew M; Pilditch, Conrad; Woodin, Sarah A; Wethey, David S; Chiantore, Mariachiara; Asnaghi, Valentina; De Juan, Silvia; Kraan, Casper; Rodil, Ivan; Savage, Candida; Van Colen, Carl

2014-06-01

Thresholds profoundly affect our understanding and management of ecosystem dynamics, but we have yet to develop practical techniques to assess the risk that thresholds will be crossed. Combining ecological knowledge of critical system interdependencies with a large-scale experiment, we tested for breaks in the ecosystem interaction network to identify threshold potential in real-world ecosystem dynamics. Our experiment with the bivalves Macomona liliana and Austrovenus stutchburyi on marine sandflats in New Zealand demonstrated that reductions in incident sunlight changed the interaction network between sediment biogeochemical fluxes, productivity, and macrofauna. By demonstrating loss of positive feedbacks and changes in the architecture of the network, we provide mechanistic evidence that stressors lead to break points in dynamics, which theory predicts predispose a system to a critical transition.

Soil life in reconstructed ecosystems: initial soil food web responses after rebuilding a forest soil profile for a climate change experiment

Treesearch

Paul T. Rygiewicz; Vicente J. Monleon; Elaine R. Ingham; Kendall J. Martin; Mark G. Johnson

2010-01-01

Disrupting ecosystem components, while transferring and reconstructing them for experiments can produce myriad responses. Establishing the extent of these biological responses as the system approaches a new equilibrium allows us more reliably to emulate comparable native systems. That is, the sensitivity of analyzing ecosystem processes in a reconstructed system is...

Pre-treatment assemblages of wood-boring beetles (Coleoptera: Buprestidae, Cerambycidae) of the hardwood ecosystem experiment

Treesearch

Jeffrey D. Holland; John T. Shukle; Hossam Eldien M. Abdel Moniem; Thomas W. Mager; Kapil R. Raje; Kyle Schnepp; Shulin Yang

2013-01-01

Longhorned beetles are a diverse and important group of insects in forest ecosystems; several species attack weakened or stressed trees, relatively few attack healthy trees, and most species use only dead and decomposing wood. We surveyed longhorned beetles and metallic wood-boring beetles using four different types of traps at 36 Hardwood Ecosystem Experiment (Indiana...

Toward a methodical framework for comprehensively assessing forest multifunctionality.

PubMed

Trogisch, Stefan; Schuldt, Andreas; Bauhus, Jürgen; Blum, Juliet A; Both, Sabine; Buscot, François; Castro-Izaguirre, Nadia; Chesters, Douglas; Durka, Walter; Eichenberg, David; Erfmeier, Alexandra; Fischer, Markus; Geißler, Christian; Germany, Markus S; Goebes, Philipp; Gutknecht, Jessica; Hahn, Christoph Zacharias; Haider, Sylvia; Härdtle, Werner; He, Jin-Sheng; Hector, Andy; Hönig, Lydia; Huang, Yuanyuan; Klein, Alexandra-Maria; Kühn, Peter; Kunz, Matthias; Leppert, Katrin N; Li, Ying; Liu, Xiaojuan; Niklaus, Pascal A; Pei, Zhiqin; Pietsch, Katherina A; Prinz, Ricarda; Proß, Tobias; Scherer-Lorenzen, Michael; Schmidt, Karsten; Scholten, Thomas; Seitz, Steffen; Song, Zhengshan; Staab, Michael; von Oheimb, Goddert; Weißbecker, Christina; Welk, Erik; Wirth, Christian; Wubet, Tesfaye; Yang, Bo; Yang, Xuefei; Zhu, Chao-Dong; Schmid, Bernhard; Ma, Keping; Bruelheide, Helge

2017-12-01

Biodiversity-ecosystem functioning (BEF) research has extended its scope from communities that are short-lived or reshape their structure annually to structurally complex forest ecosystems. The establishment of tree diversity experiments poses specific methodological challenges for assessing the multiple functions provided by forest ecosystems. In particular, methodological inconsistencies and nonstandardized protocols impede the analysis of multifunctionality within, and comparability across the increasing number of tree diversity experiments. By providing an overview on key methods currently applied in one of the largest forest biodiversity experiments, we show how methods differing in scale and simplicity can be combined to retrieve consistent data allowing novel insights into forest ecosystem functioning. Furthermore, we discuss and develop recommendations for the integration and transferability of diverse methodical approaches to present and future forest biodiversity experiments. We identified four principles that should guide basic decisions concerning method selection for tree diversity experiments and forest BEF research: (1) method selection should be directed toward maximizing data density to increase the number of measured variables in each plot. (2) Methods should cover all relevant scales of the experiment to consider scale dependencies of biodiversity effects. (3) The same variable should be evaluated with the same method across space and time for adequate larger-scale and longer-time data analysis and to reduce errors due to changing measurement protocols. (4) Standardized, practical and rapid methods for assessing biodiversity and ecosystem functions should be promoted to increase comparability among forest BEF experiments. We demonstrate that currently available methods provide us with a sophisticated toolbox to improve a synergistic understanding of forest multifunctionality. However, these methods require further adjustment to the specific requirements of structurally complex and long-lived forest ecosystems. By applying methods connecting relevant scales, trophic levels, and above- and belowground ecosystem compartments, knowledge gain from large tree diversity experiments can be optimized.

The hardwood ecosystem experiment: goals, design, and implementation

Treesearch

Rebecca A. Kalb; Cortney J. Mycroft

2013-01-01

The Hardwood Ecosystem Experiment (HEE) is a long-term, landscape-level field experiment initiated in 2006 by the Indiana Department of Natural Resources-Division of Forestry. The HEE is a multi-disciplinary, collaborative research project involving researchers from Purdue University, Indiana State University, Ball State University, Indiana University of Pennsylvania,...

Microclimate and ecological threshold responses in a warming and wetting experiment following whole-tree harvest

USDA-ARS?s Scientific Manuscript database

Ecosystem climate manipulation experiments (ECMEs) are a key tool for predicting the effects of climate on ecosystems. However, the strength of inferences drawn from these experiments depends on whether the manipulated conditions mimic future climate changes. While ECMEs have examined mean tempera...

Alternative hypotheses to explain why biodiversity-ecosystem functioning relationships are concave-up in some natural ecosystems but concave-down in manipulative experiments.

PubMed

Mora, Camilo; Danovaro, Roberto; Loreau, Michel

2014-06-25

Recent studies of the relationship between biodiversity and functioning in marine ecosystems have yielded non-saturating patterns that contrast sharply with the results of experimental studies, where ecosystem functioning rapidly saturates with increases in biodiversity. Here we provide a simple theoretical framework of three alternative hypotheses that, individually or combined, are likely to explain this contrast: i) the use of functional richness instead of species richness, ii) an increased production efficiency of species in producing biomass when more ecological interactions are present, and iii) the fact that communities are likely assembled in an ordered succession of species from low to high ecological efficiency. Our results provide theoretical support for concave-up biodiversity-ecosystem functioning relationships in natural ecosystems and confirm that the loss of species can have substantially larger effects on the functioning of natural ecosystems than anticipated from controlled manipulative experiments.

Alternative hypotheses to explain why biodiversity-ecosystem functioning relationships are concave-up in some natural ecosystems but concave-down in manipulative experiments

PubMed Central

Mora, Camilo; Danovaro, Roberto; Loreau, Michel

2014-01-01

Recent studies of the relationship between biodiversity and functioning in marine ecosystems have yielded non-saturating patterns that contrast sharply with the results of experimental studies, where ecosystem functioning rapidly saturates with increases in biodiversity. Here we provide a simple theoretical framework of three alternative hypotheses that, individually or combined, are likely to explain this contrast: i) the use of functional richness instead of species richness, ii) an increased production efficiency of species in producing biomass when more ecological interactions are present, and iii) the fact that communities are likely assembled in an ordered succession of species from low to high ecological efficiency. Our results provide theoretical support for concave-up biodiversity-ecosystem functioning relationships in natural ecosystems and confirm that the loss of species can have substantially larger effects on the functioning of natural ecosystems than anticipated from controlled manipulative experiments. PMID:24962477

Breeding bird communities of the hardwood ecosystem experiment

Treesearch

Melissa C. Malloy; John B. Dunning

2013-01-01

Declining population trends of breeding birds associated with mature forests of the eastern and central United States have been a major concern for conservationists and land managers. As a landscape-scale, long-term, manipulative experiment, the Hardwood Ecosystem Experiment (HEE) in Indiana may provide important insights into factors associated with these declines....

Balancing ecosystem values: innovative experiments for sustainable forestry—proceedings of a conference.

Treesearch

Charles E. Peterson; Douglas Maguire

2005-01-01

Balancing Ecosystem Values: Innovative Experiments for Sustainable Forestry is a compendium of more than 40 contributions from Asia, Europe, and North America. The theme encompasses experiments implemented at an operational scale to test ecological, social, or economic responses to silvicultural treatments designed to balance the complex set of...

Ecosystem Jenga!

ERIC Educational Resources Information Center

Umphlett, Natalie; Brosius, Tierney; Laungani, Ramesh; Rousseau, Joe; Leslie-Pelecky, Diandra L.

2009-01-01

To give students a tangible model of an ecosystem and have them experience what could happen if a component of that ecosystem were removed; the authors developed a hands-on, inquiry-based activity that visually demonstrates the concept of a delicately balanced ecosystem through a modification of the popular game Jenga. This activity can be…

Application experiments to trace N-P interactions in forest ecosystems

NASA Astrophysics Data System (ADS)

Krüger, Jaane; Niederberger, Jörg; Schulz, Stefanie; Lang, Friederike

2017-04-01

Phosphorus is a limited resource and there is increasing debate regarding the principles of tight P recycling. Forest ecosystems show commonly high P use efficiencies but the processes behind this phenomenon are still unresolved. In frame of the priority program "SPP 1685 Ecosystem nutrition - Forest strategies for limited phosphorus resources" around 70 researchers from different disciplines collaborate to unravel these processes. The overall hypothesis to be tested is that the P nutrition strategy of forest ecosystems at sites rich in mineral P is characterized by high P uptake efficiency (acquiring systems). In contrast, the P strategy of forest ecosystems facing low soil P stocks is characterized by highly efficient mechanisms of P recycling. To test this hypothesis, we analyzed five beech forest ecosystems on silicate rock with different parent materials representing a gradient of total P stocks (160 - 900 g P m-2, down to 1m soil depth). In fact, we found evidence confirming our hypothesis, but controls and drivers of P strategies are still unknown as other environmental variables differ. One of those might be the N content, as organisms strive to reach a specific internal N:P ratio. Thus, an additional application of N might also alter P nutrition. To test this, we established a factorial P x N application experiment at three of the study sites. With our presentation we will introduce this experiment and give a review on published P x N experiments discussing different advantages and disadvantages of different basic conditions (e.g. amount and application form, doses, sampling and statistical design, monitoring periods, budget calculation, isotopic tracing). Finally, we want to initiate a common discussion on the standardization of P x N field experiments to enable interdisciplinary and across-compartment comparisons (e.g. different land use, different climate zones, terrestrial and aquatic ecosystems).

The Missouri Ozark Forest Ecosystem Project: past, present, and future

Treesearch

Brian L. Brookshire; Randy Jensen; Daniel C. Dey

1997-01-01

In 1989, the Missouri Department of Conservation initiated a research project to examine the impacts of forest management practices on multiple ecosystem components. The Missouri Ozark Forest Ecosystem Project (MOFEP) is a landscape experiment comparing the impacts of even-aged management, uneven-aged management, and no harvesting on a wide array of ecosystem...

Response of a subalpine grassland to simulated grazing: Aboveground productivity along soil phosphorus gradients

Treesearch

C. Thiel-Egenter; A. C. Risch; M. F. Jurgensen; D. S. Page-Dumroese; B. O. Krusi; M. Schutz

2007-01-01

Interactions between grassland ecosystems and vertebrate herbivores are critical for a better understanding of ecosystem processes, but diverge widely in different ecosystems. In this study, we examined plant responses to simulated red deer (Cervus elaphus L.) grazing using clip-plot experiments in a subalpine grassland ecosystem of the Central...

Ecosystem services and emergent vulnerability in managed ecosystems: A geospatial decision-support tool

Treesearch

Colin M. Beier; Trista M. Patterson; F. Stuart Chapin III

2008-01-01

Managed ecosystems experience vulnerabilities when ecological resilience declines and key flows of ecosystem services become depleted or lost. Drivers of vulnerability often include local management actions in conjunction with other external, larger scale factors. To translate these concepts to management applications, we developed a conceptual model of feedbacks...

Climate Change Across Seasons Experiment (CCASE): A new method for simulating future climate in seasonally snow-covered ecosystems.

PubMed

Templer, Pamela H; Reinmann, Andrew B; Sanders-DeMott, Rebecca; Sorensen, Patrick O; Juice, Stephanie M; Bowles, Francis; Sofen, Laura E; Harrison, Jamie L; Halm, Ian; Rustad, Lindsey; Martin, Mary E; Grant, Nicholas

2017-01-01

Climate models project an increase in mean annual air temperatures and a reduction in the depth and duration of winter snowpack for many mid and high latitude and high elevation seasonally snow-covered ecosystems over the next century. The combined effects of these changes in climate will lead to warmer soils in the growing season and increased frequency of soil freeze-thaw cycles (FTCs) in winter due to the loss of a continuous, insulating snowpack. Previous experiments have warmed soils or removed snow via shoveling or with shelters to mimic projected declines in the winter snowpack. To our knowledge, no experiment has examined the interactive effects of declining snowpack and increased frequency of soil FTCs, combined with soil warming in the snow-free season on terrestrial ecosystems. In addition, none have mimicked directly the projected increase in soil FTC frequency in tall statured forests that is expected as a result of a loss of insulating snow in winter. We established the Climate Change Across Seasons Experiment (CCASE) at Hubbard Brook Experimental Forest in the White Mountains of New Hampshire in 2012 to assess the combined effects of these changes in climate on a variety of pedoclimate conditions, biogeochemical processes, and ecology of northern hardwood forests. This paper demonstrates the feasibility of creating soil FTC events in a tall statured ecosystem in winter to simulate the projected increase in soil FTC frequency over the next century and combines this projected change in winter climate with ecosystem warming throughout the snow-free season. Together, this experiment provides a new and more comprehensive approach for climate change experiments that can be adopted in other seasonally snow-covered ecosystems to simulate expected changes resulting from global air temperature rise.

Climate Change Across Seasons Experiment (CCASE): A new method for simulating future climate in seasonally snow-covered ecosystems

PubMed Central

Templer, Pamela H.; Reinmann, Andrew B.; Sanders-DeMott, Rebecca; Sorensen, Patrick O.; Juice, Stephanie M.; Bowles, Francis; Sofen, Laura E.; Harrison, Jamie L.; Halm, Ian; Rustad, Lindsey; Martin, Mary E.; Grant, Nicholas

2017-01-01

Climate models project an increase in mean annual air temperatures and a reduction in the depth and duration of winter snowpack for many mid and high latitude and high elevation seasonally snow-covered ecosystems over the next century. The combined effects of these changes in climate will lead to warmer soils in the growing season and increased frequency of soil freeze-thaw cycles (FTCs) in winter due to the loss of a continuous, insulating snowpack. Previous experiments have warmed soils or removed snow via shoveling or with shelters to mimic projected declines in the winter snowpack. To our knowledge, no experiment has examined the interactive effects of declining snowpack and increased frequency of soil FTCs, combined with soil warming in the snow-free season on terrestrial ecosystems. In addition, none have mimicked directly the projected increase in soil FTC frequency in tall statured forests that is expected as a result of a loss of insulating snow in winter. We established the Climate Change Across Seasons Experiment (CCASE) at Hubbard Brook Experimental Forest in the White Mountains of New Hampshire in 2012 to assess the combined effects of these changes in climate on a variety of pedoclimate conditions, biogeochemical processes, and ecology of northern hardwood forests. This paper demonstrates the feasibility of creating soil FTC events in a tall statured ecosystem in winter to simulate the projected increase in soil FTC frequency over the next century and combines this projected change in winter climate with ecosystem warming throughout the snow-free season. Together, this experiment provides a new and more comprehensive approach for climate change experiments that can be adopted in other seasonally snow-covered ecosystems to simulate expected changes resulting from global air temperature rise. PMID:28207766

Biodiversity and ecosystem stability in a decade-long grassland experiment.

PubMed

Tilman, David; Reich, Peter B; Knops, Johannes M H

2006-06-01

Human-driven ecosystem simplification has highlighted questions about how the number of species in an ecosystem influences its functioning. Although biodiversity is now known to affect ecosystem productivity, its effects on stability are debated. Here we present a long-term experimental field test of the diversity-stability hypothesis. During a decade of data collection in an experiment that directly controlled the number of perennial prairie species, growing-season climate varied considerably, causing year-to-year variation in abundances of plant species and in ecosystem productivity. We found that greater numbers of plant species led to greater temporal stability of ecosystem annual aboveground plant production. In particular, the decadal temporal stability of the ecosystem, whether measured with intervals of two, five or ten years, was significantly greater at higher plant diversity and tended to increase as plots matured. Ecosystem stability was also positively dependent on root mass, which is a measure of perenniating biomass. Temporal stability of the ecosystem increased with diversity, despite a lower temporal stability of individual species, because of both portfolio (statistical averaging) and overyielding effects. However, we found no evidence of a covariance effect. Our results indicate that the reliable, efficient and sustainable supply of some foods (for example, livestock fodder), biofuels and ecosystem services can be enhanced by the use of biodiversity.

PERSISTENCE OF DESERTIFIED ECOSYSTEMS: EXPLANATIONS AND IMPLICATIONS

EPA Science Inventory

Studies of rainfall partitioning by shrubs, responses of shrub-dominated ecosystems to herbicide treatment, and experiments using drought and supplemental rainfall were conducted to test the hypothesis that the shrub-dominated ecosystems that have replaced desert grasslands are r...

Loss of Rare Fish Species from Tropical Floodplain Food Webs Affects Community Structure and Ecosystem Multifunctionality in a Mesocosm Experiment

PubMed Central

Pendleton, Richard M.; Hoeinghaus, David J.; Gomes, Luiz C.; Agostinho, Angelo A.

2014-01-01

Experiments with realistic scenarios of species loss from multitrophic ecosystems may improve insight into how biodiversity affects ecosystem functioning. Using 1000 L mesocoms, we examined effects of nonrandom species loss on community structure and ecosystem functioning of experimental food webs based on multitrophic tropical floodplain lagoon ecosystems. Realistic biodiversity scenarios were developed based on long-term field surveys, and experimental assemblages replicated sequential loss of rare species which occurred across all trophic levels of these complex food webs. Response variables represented multiple components of ecosystem functioning, including nutrient cycling, primary and secondary production, organic matter accumulation and whole ecosystem metabolism. Species richness significantly affected ecosystem function, even after statistically controlling for potentially confounding factors such as total biomass and direct trophic interactions. Overall, loss of rare species was generally associated with lower nutrient concentrations, phytoplankton and zooplankton densities, and whole ecosystem metabolism when compared with more diverse assemblages. This pattern was also observed for overall ecosystem multifunctionality, a combined metric representing the ability of an ecosystem to simultaneously maintain multiple functions. One key exception was attributed to time-dependent effects of intraguild predation, which initially increased values for most ecosystem response variables, but resulted in decreases over time likely due to reduced nutrient remineralization by surviving predators. At the same time, loss of species did not result in strong trophic cascades, possibly a result of compensation and complexity of these multitrophic ecosystems along with a dominance of bottom-up effects. Our results indicate that although rare species may comprise minor components of communities, their loss can have profound ecosystem consequences across multiple trophic levels due to a combination of direct and indirect effects in diverse multitrophic ecosystems. PMID:24416246

Soil life in reconstructed ecosystems: Initial soil food web responses after rebuilding a forest soil profile for a climate change experiment

EPA Science Inventory

Disrupting ecosystem components, while transferring and reconstructing them for experiments can produce myriad responses. Establishing the extent of these biological responses as the system approaches a new equilibrium allows us more reliably to emulate comparable native systems....

Designing Informal Learning Experiences for Early Career Academics Using a Knowledge Ecosystem Model

ERIC Educational Resources Information Center

Miller, Faye; Partridge, Helen; Bruce, Christine; Hemmings, Brian

2017-01-01

This article presents a "knowledge ecosystem" model of how early career academics experience using information to learn while building their social networks for developmental purposes. Developed using grounded theory methodology, the model offers a way of conceptualising how to empower early career academics through (1) agency…

Environmental Science: High-School Science Fair Experiments.

ERIC Educational Resources Information Center

Dashefsky, H. Steven

This book contains 23 suggestions for experiments involving environmental science that can be used to create a science fair project. Aimed at grades 10-12, a wide range of environmental topics is covered. These topics include soil ecosystems, aquatic ecosystems, applied ecology, global warming and the greenhouse effect, deforestation and…

Long-term and large-scale perspectives on the relationship between biodiversity and ecosystem functioning

USGS Publications Warehouse

Symstad, A.J.; Chapin, F. S.; Wall, D.H.; Gross, K.L.; Huenneke, L.F.; Mittelbach, G.G.; Peters, Debra P.C.; Tilman, D.

2003-01-01

In a growing body of literature from a variety of ecosystems is strong evidence that various components of biodiversity have significant impacts on ecosystem functioning. However, much of this evidence comes from short-term, small-scale experiments in which communities are synthesized from relatively small species pools and conditions are highly controlled. Extrapolation of the results of such experiments to longer time scales and larger spatial scales—those of whole ecosystems—is difficult because the experiments do not incorporate natural processes such as recruitment limitation and colonization of new species. We show how long-term study of planned and accidental changes in species richness and composition suggests that the effects of biodiversity on ecosystem functioning will vary over time and space. More important, we also highlight areas of uncertainty that need to be addressed through coordinated cross-scale and cross-site research.

Using Ecosystem Experiments to Improve Vegetation Models

DOE PAGES

Medlyn, Belinda; Zaehle, S; DeKauwe, Martin G.; ...

2015-05-21

Ecosystem responses to rising CO2 concentrations are a major source of uncertainty in climate change projections. Data from ecosystem-scale Free-Air CO2 Enrichment (FACE) experiments provide a unique opportunity to reduce this uncertainty. The recent FACE Model–Data Synthesis project aimed to use the information gathered in two forest FACE experiments to assess and improve land ecosystem models. A new 'assumption-centred' model intercomparison approach was used, in which participating models were evaluated against experimental data based on the ways in which they represent key ecological processes. Identifying and evaluating the main assumptions caused differences among models, and the assumption-centered approach produced amore » clear roadmap for reducing model uncertainty. We explain this approach and summarize the resulting research agenda. We encourage the application of this approach in other model intercomparison projects to fundamentally improve predictive understanding of the Earth system.« less

Biogeomorphic feedback between plant growth and flooding causes alternative stable states in an experimental floodplain

NASA Astrophysics Data System (ADS)

Wang, Chen; Wang, Qiao; Meire, Dieter; Ma, Wandong; Wu, Chuanqing; Meng, Zhen; Van de Koppel, Johan; Troch, Peter; Verhoeven, Ronny; De Mulder, Tom; Temmerman, Stijn

2016-07-01

It is important to understand the mechanisms of vegetation establishment on bare substrate in a disturbance-driven ecosystem because of many valuable ecosystem services. This study tested for empirical indications of local alternative stable states controlled by biogeomorphic feedbacks using flume experiments with alfalfa: (1) single flood experiments different in flood intensity and plant growth, (2) long-term evolution experiments with repeated flooding and seeding. We observed: (1) a combination of thresholds in plant growth and flooding magnitude for upgrowing seedlings to survive; (2) bimodality in vegetation biomass after floods indicating the existence of two alternative states, either densely vegetated or bare; (3) facilitation of vegetation establishment by the spatial pattern formation of channels and sand bars. In conclusion, empirical indicators were demonstrated for local alternative stable states in a disturbance-driven ecosystem associated with biogeomorphic feedbacks, which could contribute to the protection and restoration of vegetation in such ecosystems.

Leveraging 35 years of Pinus taeda research in the southeastern US to constrain forest carbon cycle predictions: regional data assimilation using ecosystem experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thomas, R. Quinn; Brooks, Evan B.; Jersild, Annika L.

Predicting how forest carbon cycling will change in response to climate change and management depends on the collective knowledge from measurements across environmental gradients, ecosystem manipulations of global change factors, and mathematical models. Formally integrating these sources of knowledge through data assimilation, or model–data fusion, allows the use of past observations to constrain model parameters and estimate prediction uncertainty. Data assimilation (DA) focused on the regional scale has the opportunity to integrate data from both environmental gradients and experimental studies to constrain model parameters. Here, we introduce a hierarchical Bayesian DA approach (Data Assimilation to Predict Productivity for Ecosystems and Regions,more » DAPPER) that uses observations of carbon stocks, carbon fluxes, water fluxes, and vegetation dynamics from loblolly pine plantation ecosystems across the southeastern US to constrain parameters in a modified version of the Physiological Principles Predicting Growth (3-PG) forest growth model. The observations included major experiments that manipulated atmospheric carbon dioxide (CO 2) concentration, water, and nutrients, along with nonexperimental surveys that spanned environmental gradients across an 8.6 × 10 5 km 2 region. We optimized regionally representative posterior distributions for model parameters, which dependably predicted data from plots withheld from the data assimilation. While the mean bias in predictions of nutrient fertilization experiments, irrigation experiments, and CO 2 enrichment experiments was low, future work needs to focus modifications to model structures that decrease the bias in predictions of drought experiments. Predictions of how growth responded to elevated CO 2 strongly depended on whether ecosystem experiments were assimilated and whether the assimilated field plots in the CO 2 study were allowed to have different mortality parameters than the other field plots in the region. We present predictions of stem biomass productivity under elevated CO 2, decreased precipitation, and increased nutrient availability that include estimates of uncertainty for the southeastern US. Overall, we (1) demonstrated how three decades of research in southeastern US planted pine forests can be used to develop DA techniques that use multiple locations, multiple data streams, and multiple ecosystem experiment types to optimize parameters and (2) developed a tool for the development of future predictions of forest productivity for natural resource managers that leverage a rich dataset of integrated ecosystem observations across a region.« less

Leveraging 35 years of Pinus taeda research in the southeastern US to constrain forest carbon cycle predictions: regional data assimilation using ecosystem experiments

DOE PAGES

Thomas, R. Quinn; Brooks, Evan B.; Jersild, Annika L.; ...

2017-07-26

Predicting how forest carbon cycling will change in response to climate change and management depends on the collective knowledge from measurements across environmental gradients, ecosystem manipulations of global change factors, and mathematical models. Formally integrating these sources of knowledge through data assimilation, or model–data fusion, allows the use of past observations to constrain model parameters and estimate prediction uncertainty. Data assimilation (DA) focused on the regional scale has the opportunity to integrate data from both environmental gradients and experimental studies to constrain model parameters. Here, we introduce a hierarchical Bayesian DA approach (Data Assimilation to Predict Productivity for Ecosystems and Regions,more » DAPPER) that uses observations of carbon stocks, carbon fluxes, water fluxes, and vegetation dynamics from loblolly pine plantation ecosystems across the southeastern US to constrain parameters in a modified version of the Physiological Principles Predicting Growth (3-PG) forest growth model. The observations included major experiments that manipulated atmospheric carbon dioxide (CO 2) concentration, water, and nutrients, along with nonexperimental surveys that spanned environmental gradients across an 8.6 × 10 5 km 2 region. We optimized regionally representative posterior distributions for model parameters, which dependably predicted data from plots withheld from the data assimilation. While the mean bias in predictions of nutrient fertilization experiments, irrigation experiments, and CO 2 enrichment experiments was low, future work needs to focus modifications to model structures that decrease the bias in predictions of drought experiments. Predictions of how growth responded to elevated CO 2 strongly depended on whether ecosystem experiments were assimilated and whether the assimilated field plots in the CO 2 study were allowed to have different mortality parameters than the other field plots in the region. We present predictions of stem biomass productivity under elevated CO 2, decreased precipitation, and increased nutrient availability that include estimates of uncertainty for the southeastern US. Overall, we (1) demonstrated how three decades of research in southeastern US planted pine forests can be used to develop DA techniques that use multiple locations, multiple data streams, and multiple ecosystem experiment types to optimize parameters and (2) developed a tool for the development of future predictions of forest productivity for natural resource managers that leverage a rich dataset of integrated ecosystem observations across a region.« less

Leveraging 35 years of Pinus taeda research in the southeastern US to constrain forest carbon cycle predictions: regional data assimilation using ecosystem experiments

NASA Astrophysics Data System (ADS)

Quinn Thomas, R.; Brooks, Evan B.; Jersild, Annika L.; Ward, Eric J.; Wynne, Randolph H.; Albaugh, Timothy J.; Dinon-Aldridge, Heather; Burkhart, Harold E.; Domec, Jean-Christophe; Fox, Thomas R.; Gonzalez-Benecke, Carlos A.; Martin, Timothy A.; Noormets, Asko; Sampson, David A.; Teskey, Robert O.

2017-07-01

Predicting how forest carbon cycling will change in response to climate change and management depends on the collective knowledge from measurements across environmental gradients, ecosystem manipulations of global change factors, and mathematical models. Formally integrating these sources of knowledge through data assimilation, or model-data fusion, allows the use of past observations to constrain model parameters and estimate prediction uncertainty. Data assimilation (DA) focused on the regional scale has the opportunity to integrate data from both environmental gradients and experimental studies to constrain model parameters. Here, we introduce a hierarchical Bayesian DA approach (Data Assimilation to Predict Productivity for Ecosystems and Regions, DAPPER) that uses observations of carbon stocks, carbon fluxes, water fluxes, and vegetation dynamics from loblolly pine plantation ecosystems across the southeastern US to constrain parameters in a modified version of the Physiological Principles Predicting Growth (3-PG) forest growth model. The observations included major experiments that manipulated atmospheric carbon dioxide (CO2) concentration, water, and nutrients, along with nonexperimental surveys that spanned environmental gradients across an 8.6 × 105 km2 region. We optimized regionally representative posterior distributions for model parameters, which dependably predicted data from plots withheld from the data assimilation. While the mean bias in predictions of nutrient fertilization experiments, irrigation experiments, and CO2 enrichment experiments was low, future work needs to focus modifications to model structures that decrease the bias in predictions of drought experiments. Predictions of how growth responded to elevated CO2 strongly depended on whether ecosystem experiments were assimilated and whether the assimilated field plots in the CO2 study were allowed to have different mortality parameters than the other field plots in the region. We present predictions of stem biomass productivity under elevated CO2, decreased precipitation, and increased nutrient availability that include estimates of uncertainty for the southeastern US. Overall, we (1) demonstrated how three decades of research in southeastern US planted pine forests can be used to develop DA techniques that use multiple locations, multiple data streams, and multiple ecosystem experiment types to optimize parameters and (2) developed a tool for the development of future predictions of forest productivity for natural resource managers that leverage a rich dataset of integrated ecosystem observations across a region.

The robustness of ecosystems to the species loss of community

NASA Astrophysics Data System (ADS)

Cai, Qing; Liu, Jiming

2016-10-01

To study the robustness of ecosystems is crucial to promote the sustainable development of human society. This paper aims to analyze the robustness of ecosystems from an interesting viewpoint of the species loss of community. Unlike the existing definitions, we first introduce the notion of a community as a population of species belonging to the same trophic level. We then put forward a novel multiobjective optimization model which can be utilized to discover community structures from arbitrary unipartite networks. Because an ecosystem is commonly represented as a multipartite network, we further introduce a mechanism of competition among species whereby a multipartite network is transformed into a unipartite signed network without loss of species interaction information. Finally, we examine three strategies to test the robustness of an ecosystem. Our experiments indicate that ecosystems are robust to random species loss of community but fragile to target ones. We also investigate the relationships between the robustness of an ecosystem and that of its community composed network both to species loss. Our experiments indicate that the robustness analysis of a large-scale ecosystem to species loss may be akin to that of its community composed network which is usually small in size.

Contrasting Ecosystem-Effects of Morphologically Similar Copepods

PubMed Central

Matthews, Blake; Hausch, Stephen; Winter, Christian; Suttle, Curtis A.; Shurin, Jonathan B.

2011-01-01

Organisms alter the biotic and abiotic conditions of ecosystems. They can modulate the availability of resources to other species (ecosystem engineering) and shape selection pressures on other organisms (niche construction). Very little is known about how the engineering effects of organisms vary among and within species, and, as a result, the ecosystem consequences of species diversification and phenotypic evolution are poorly understood. Here, using a common gardening experiment, we test whether morphologically similar species and populations of Diaptomidae copepods (Leptodiaptomus ashlandi, Hesperodiaptomus franciscanus, Skistodiaptomus oregonensis) have similar or different effects on the structure and function of freshwater ecosystems. We found that copepod species had contrasting effects on algal biomass, ammonium concentrations, and sedimentation rates, and that copepod populations had contrasting effects on prokaryote abundance, sedimentation rates, and gross primary productivity. The average size of ecosystem-effect contrasts between species was similar to those between populations, and was comparable to those between fish species and populations measured in previous common gardening experiments. Our results suggest that subtle morphological variation among and within species can cause multifarious and divergent ecosystem-effects. We conclude that using morphological trait variation to assess the functional similarity of organisms may underestimate the importance of species and population diversity for ecosystem functioning. PMID:22140432

Methods to test the interactive effects of drought and plant invasion on ecosystem structure and function using complementary common garden and field experiments.

PubMed

Alba, Christina; NeSmith, Julienne E; Fahey, Catherine; Angelini, Christine; Flory, Stephen Luke

2017-03-01

Abiotic global change drivers affect ecosystem structure and function, but how they interact with biotic factors such as invasive plants is understudied. Such interactions may be additive, synergistic, or offsetting, and difficult to predict. We present methods to test the individual and interactive effects of drought and plant invasion on native ecosystems. We coupled a factorial common garden experiment containing resident communities exposed to drought (imposed with rainout shelters) and invasion with a field experiment where the invader was removed from sites spanning a natural soil moisture gradient. We detail treatments and their effects on abiotic conditions, including soil moisture, light, temperature, and humidity, which shape community and ecosystem responses. Ambient precipitation during the garden experiment exceeded historic norms despite severe drought in prior years. Soil moisture was 48% lower in drought than ambient plots, but the invader largely offset drought effects. Additionally, temperature and light were lower and humidity higher in invaded plots. Field sites spanned up to a 10-fold range in soil moisture and up to a 2.5-fold range in light availability. Invaded and resident vegetation did not differentially mediate soil moisture, unlike in the garden experiment. Herbicide effectively removed invaded and resident vegetation, with removal having site-specific effects on soil moisture and light availability. However, light was generally higher in invader-removal than control plots, whereas resident removal had less effect on light, similar to the garden experiment. Invasion mitigated a constellation of abiotic conditions associated with drought stress in the garden experiment. In the field, where other factors co-varied, these patterns did not emerge. Still, neither experiment suggested that drought and invasion will have synergistic negative effects on ecosystems, although invasion can limit light availability. Coupling factorial garden experiments with field experiments across environmental gradients will be effective for predicting how multiple stressors interact in natural systems.

13C AND 15N IN MICROARTHROPODS REVEAL LITTLE RESPONSE OF DOUGLAS-FIR ECOSYSTEMS TO CLIMATE CHANGE

EPA Science Inventory

Understanding ecosystem carbon (C) and nitrogen (N) cycling under global change requires experiments maintaining natural interactions among soil structure, soil communities, nutrient availability, and plant growth. In model Douglas-fir ecosystems maintained for five growing seaso...

Contrasting biodiversity-ecosystem functioning relationships in phylogenetic and functional diversity.

PubMed

Steudel, Bastian; Hallmann, Christine; Lorenz, Maike; Abrahamczyk, Stefan; Prinz, Kathleen; Herrfurth, Cornelia; Feussner, Ivo; Martini, Johannes W R; Kessler, Michael

2016-10-01

It is well known that ecosystem functioning is positively influenced by biodiversity. Most biodiversity-ecosystem functioning experiments have measured biodiversity based on species richness or phylogenetic relationships. However, theoretical and empirical evidence suggests that ecosystem functioning should be more closely related to functional diversity than to species richness. We applied different metrics of biodiversity in an artificial biodiversity-ecosystem functioning experiment using 64 species of green microalgae in combinations of two to 16 species. We found that phylogenetic and functional diversity were positively correlated with biomass overyield, driven by their strong correlation with species richness. At low species richness, no significant correlation between overyield and functional and phylogenetic diversity was found. However, at high species richness (16 species), we found a positive relationship of overyield with functional diversity and a negative relationship with phylogenetic diversity. We show that negative phylogenetic diversity-ecosystem functioning relationships can result from interspecific growth inhibition. The opposing performances of facilitation (functional diversity) and inhibition (phylogenetic diversity) we observed at the 16 species level suggest that phylogenetic diversity is not always a good proxy for functional diversity and that results from experiments with low species numbers may underestimate negative species interactions. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

What have we learned from global change manipulative experiments in China? A meta-analysis

PubMed Central

Fu, Zheng; Niu, Shuli; Dukes, Jeffrey S.

2015-01-01

Although China has the largest population in the world, a faster rate of warming than the global average, and an active global change research program, results from many of the global change experiments in Chinese terrestrial ecosystems have not been included in global syntheses. Here, we specifically analyze the observed responses of carbon (C) and nitrogen (N) cycling in global change manipulative experiments in China, and compare these responses to those from other regions of the world. Most global change factors, vegetation types, and treatment methods that have been studied or used elsewhere in the world have also been studied and applied in China. The responses of terrestrial ecosystem C and N cycles to N addition and climate warming in China are similar in both direction and intensity to those reported in global syntheses. In Chinese ecosystems as elsewhere, N addition significantly increased aboveground (AGB) and belowground biomass (BGB), litter mass, dissolved organic C, net ecosystem productivity (NEP), and gross ecosystem productivity (GEP). Warming stimulated AGB, BGB and the root-shoot ratio. Increasing precipitation accelerated GEP, NEP, microbial respiration, soil respiration, and ecosystem respiration. Our findings complement and support previous global syntheses and provide insight into regional responses to global change. PMID:26205333

Integration of Long term experiments on terrestrial ecosystem in AnaEE-France Research Infrastructure : concept and adding value

NASA Astrophysics Data System (ADS)

Chanzy, André; Chabbi, Abad; Houot, Sabine; Lafolie, François; Pichot, Christian; Raynal, Hélène; Saint-André, Laurent; Clobert, Jean; Greiveldinger, Lucile

2015-04-01

Continental ecosystems represent a critical zone that provide key ecological services to human populations like biomass production, that participate to the regulation of the global biogeochemical cycles and contribute and contribute to the maintenance of air and water quality. Global changes effects on continental ecosystems are likely to impact the fate of humanity, which is thus facing numerous challenges, such as an increasing demand for food and energy, competition for land and water use, or rapid climate warming. Hence, scientific progress in our understanding of the continental critical zone will come from studies that address how biotic and abiotic processes react to global changes. Long term experiments are required to take into account ecosystem inertia and feedback loops and to characterize trends and threshold in ecosystem dynamics. In France, 20 long-term experiments on terrestrial ecosystems are gathered within a single Research Infrastructure: ANAEE-France (http://www.anaee-s.fr), which is a part of AnaEE-Europe (http://www.anaee.com/). Each experiment consist in applying differentiated pressures on different plot over a long period (>20 years) representative of a range of management options. The originality of such infrastructure is a combination of experimental set up and long-term monitoring of simultaneous measurements of key ecosystem variables and parameters through a multi-disciplinary approach and replications of each treatment that improve the statistical strength of the results. The sites encompass gradients of climate conditions, ecosystem complexity and/or management, and can be used for calibration/validation of ecosystem functioning models as well as for the design of ecosystem management strategies. Gathering those experiments in a single research infrastructure is an important issue to enhance their visibility and increase the number of hosting scientific team by offering a range of services. These are: • Access to the ongoing long term experiments to implement novel observational systems. Through active collaboration with the teams in charge of the experiments, users will take advantage of the site characterization, historical data, monitoring setup and access to different treatments experimental field with differentiated properties induced by repeated treatment. • Access to soil and vegetation samples collected at different dates that may be reanalyzed a posteriori to take profit of technological progress. • Delivery of reference data on ecosystems subjected to a gradient of anthropogenic and climatic pressures. The research infrastructure level is appropriate to implement a harmonization policy for the measurement and observation protocols. Moreover it offers the possibility of developing an ambitious strategy in integrating data and models. These can contribute to the experimental process for protocol design or data quality control. Moreover, they offer an efficient way for promoting data reuse thus giving a strong added value to the existing data bases. Therefore, building interoperability between models and experimental platform data bases is an important objective to improve the quality of experimental infrastructure and provide users with seamless and integrated information systems. We present how this is operated in AnaEE-France with different tasks as the development of a controlled vocabulary, tools to annotate data and model variables with metadata based on ontologies and the development of webservice to harvest data from the data base to the modelling platform environment. Finally some examples of key results taking profit of the range of experiments are provided.

Missouri Ozark Forest Ecosystem Project: the experiment

Treesearch

Steven L. Sheriff

2002-01-01

Missouri Ozark Forest Ecosystem Project (MOFEP) is a unique experiment to learn about the impacts of management practices on a forest system. Three forest management practices (uneven-aged management, even-aged management, and no-harvest management) as practiced by the Missouri Department of Conservation were randomly assigned to nine forest management sites using a...

Glacier Lakes Ecosystem Experiment Site: an "Experimental" wilderness

Treesearch

Douglas G. Fox; Anna W. Schoettle; Frank A. Vertucci

1987-01-01

This site, selected to be representative of high-mountain wilderness ecosystems, is being used to study the effects of air pollution and atmospheric deposition In alpine and subalpine, terrestrial and aquatic biotic communities. The research program includes (a) short-term experiments designed to quantify the response of system components hypothesized to be most...

Regional zooplankton dispersal provides spatial insurance for ecosystem function.

PubMed

Symons, Celia C; Arnott, Shelley E

2013-05-01

Changing environmental conditions are affecting diversity and ecosystem function globally. Theory suggests that dispersal from a regional species pool may buffer against changes in local community diversity and ecosystem function after a disturbance through the establishment of functionally redundant tolerant species. The spatial insurance provided by dispersal may decrease through time after environmental change as the local community monopolizes resources and reduces community invasibility. To test for evidence of the spatial insurance hypothesis and to determine the role dispersal timing plays in this response we conducted a field experiment using crustacean zooplankton communities in a subarctic region that is expected to be highly impacted by climate change - Churchill, Canada. Three experiments were conducted where nutrients, salt, and dispersal were manipulated. The three experiments differed in time-since-disturbance that the dispersers were added. We found that coarse measures of diversity (i.e. species richness, evenness, and Shannon-Weiner diversity) were generally resistant to large magnitude disturbances, and that dispersal had the most impact on diversity when dispersers were added shortly after disturbance. Ecosystem functioning (chl-a) was degraded in disturbed communities, but dispersal recovered ecosystem function to undisturbed levels. This spatial insurance for ecosystem function was mediated through changes in community composition and the relative abundance of functional groups. Results suggest that regional diversity and habitat connectivity will be important in the future to maintain ecosystem function by introducing functionally redundant species to promote compensatory dynamics. © 2012 Blackwell Publishing Ltd.

Nutrient enrichment, biodiversity loss, and consequent declines in ecosystem productivity.

PubMed

Isbell, Forest; Reich, Peter B; Tilman, David; Hobbie, Sarah E; Polasky, Stephen; Binder, Seth

2013-07-16

Anthropogenic drivers of environmental change often have multiple effects, including changes in biodiversity, species composition, and ecosystem functioning. It remains unknown whether such shifts in biodiversity and species composition may, themselves, be major contributors to the total, long-term impacts of anthropogenic drivers on ecosystem functioning. Moreover, although numerous experiments have shown that random losses of species impact the functioning of ecosystems, human-caused losses of biodiversity are rarely random. Here we use results from long-term grassland field experiments to test for direct effects of chronic nutrient enrichment on ecosystem productivity, and for indirect effects of enrichment on productivity mediated by resultant species losses. We found that ecosystem productivity decreased through time most in plots that lost the most species. Chronic nitrogen addition also led to the nonrandom loss of initially dominant native perennial C4 grasses. This loss of dominant plant species was associated with twice as great a loss of productivity per lost species than occurred with random species loss in a nearby biodiversity experiment. Thus, although chronic nitrogen enrichment initially increased productivity, it also led to loss of plant species, including initially dominant species, which then caused substantial diminishing returns from nitrogen fertilization. In contrast, elevated CO2 did not decrease grassland plant diversity, and it consistently promoted productivity over time. Our results support the hypothesis that the long-term impacts of anthropogenic drivers of environmental change on ecosystem functioning can strongly depend on how such drivers gradually decrease biodiversity and restructure communities.

Salinity and Temperature Tolerance Experiments on Selected Florida Bay Mollusks

USGS Publications Warehouse

Murray, James B.; Wingard, G. Lynn

2006-01-01

The ultimate goal of the Comprehensive Everglades Restoration Plan (CERP) is to restore and preserve the unique ecosystems of South Florida, including the estuaries. Understanding the effect of salinity and temperature changes, beyond typical oscillations, on the biota of South Florida's estuaries is a necessary component of achieving the goal of restoring the estuaries. The U.S. Geological Survey has been actively involved in researching the history of the South Florida Ecosystem, to provide targets, performance measures, and baseline data for restoration managers. These experiments addressed two aspects of ecosystem history research: 1) determining the utility of using molluscan shells as recorders of change in water chemistry parameters, primarily salinity, and 2) enhancing our in situ observations on modern assemblages by exceeding typically observed aquatic conditions. This set of experiments expanded our understanding of the effects of salinity, temperature and other water chemistry parameters on the reproduction, growth and overall survivability of key species of mollusks used in interpreting sediment core data. Observations on mollusks, plants and microbes made as part of these experiments have further refined our knowledge and understanding of the effects of ecosystem feedback and the role salinity and temperature play in ecosystem stability. The results have demonstrated the viability of several molluscan species as indicators of atypical salinity, and possibly temperature, modulations. For example Cerithium muscarum and Bulla striata demonstrated an ability to withstand a broad salinity and temperature range, with reproduction occurring in atypically high salinities and temperatures. These experiments also provided calibration data for the shell biogeochemistry of Chione cancellata and the possible use of this species as a water chemistry recorder. Observations made in the mesocosms, on a scale not normally observable in the field, have led to new questions about the influence of salinity on the localized ecosystem. The next phase of these experiments; to calibrate growth rate and reproductive viability in atypical salinities is currently underway.

The economic value of ecosystem services from and for wilderness.

Treesearch

T. Patterson

2007-01-01

Creative experiments are bringing values of ecosystem services into the marketplace including carbon markets, wetland and habitat banking, water temperature credits, certifications, and tax incentives. Market values have helped raise awareness for ecosystem service contributions to quality of life, and help harness funds for their protection. Achieving these outcomes...

Developing ecosystem service indicators: Experiences and lessons learned from sub-global assessments and other initiatives - new

EPA Science Inventory

People depend upon ecosystems to supply a range of services necessary for their survival and well-being. Ecosystem service indicators are critical for knowing whether or not these essential services are being maintained and used in a sustainable manner, thus enabling policy maker...

Warming alters the metabolic balance of ecosystems

PubMed Central

Yvon-Durocher, Gabriel; Jones, J. Iwan; Trimmer, Mark; Woodward, Guy; Montoya, Jose M.

2010-01-01

The carbon cycle modulates climate change, via the regulation of atmospheric CO2, and it represents one of the most important services provided by ecosystems. However, considerable uncertainties remain concerning potential feedback between the biota and the climate. In particular, it is unclear how global warming will affect the metabolic balance between the photosynthetic fixation and respiratory release of CO2 at the ecosystem scale. Here, we present a combination of experimental field data from freshwater mesocosms, and theoretical predictions derived from the metabolic theory of ecology to investigate whether warming will alter the capacity of ecosystems to absorb CO2. Our manipulative experiment simulated the temperature increases predicted for the end of the century and revealed that ecosystem respiration increased at a faster rate than primary production, reducing carbon sequestration by 13 per cent. These results confirmed our theoretical predictions based on the differential activation energies of these two processes. Using only the activation energies for whole ecosystem photosynthesis and respiration we provide a theoretical prediction that accurately quantified the precise magnitude of the reduction in carbon sequestration observed experimentally. We suggest the combination of whole-ecosystem manipulative experiments and ecological theory is one of the most promising and fruitful research areas to predict the impacts of climate change on key ecosystem services. PMID:20513719

Bats of the hardwood ecosystem experiment before timber harvest: assessment and prognosis

Treesearch

Jeremy J. Sheets; John O. Whitaker; Virgil Jr. Brack; Dale W. Sparks

2013-01-01

Before experimental harvest of the Yellowwood (YW) and Morgan-Monroe (MM) State Forests (Indiana) as part of the Hardwood Ecosystem Experiment, bats were sampled using mist nets at four locations in MM and five locations in YW during each summer 2006 through 2008. Netting locations were adjacent to forest stands scheduled for experimental manipulations following...

Past is prologue: a synthesis of state forest management activities and hardwood ecosystem experiment pre-treatment results

Treesearch

G. Scott Haulton

2013-01-01

Disturbance plays an important role in forest development processes. Present-day forest condition can be viewed as the cumulative result of various historical disturbance events; therefore, an understanding of disturbance history is important when describing overall forest condition. Pre-treatment studies of the Hardwood Ecosystem Experiment (HEE) have described...

Ecological restoration experiments (1992-2007) at the G. A. Pearson Natural Area, Fort Valley Experimental Forest

Treesearch

Margaret M. Moore; W. Wallace Covington; Peter Z. Fule; Stephen C. Hart; Thomas E. Kolb; Joy N. Mast; Stephen S. Sackett; Michael R. Wagner

2008-01-01

In 1992 an experiment was initiated at the G. A. Pearson Natural Area on the Fort Valley Experimental Forest to evaluate long-term ecosystem responses to two restoration treatments: thinning only and thinning with prescribed burning. Fifteen years of key findings about tree physiology, herbaceous, and ecosystem responses are presented.

The western arctic linkage experiment (WALE): overview and synthesis

Treesearch

A.D. McGuire; J. Walsh; J.S. Kimball; J.S. Clein; S.E. Euskirdhen; S. Drobot; U.C. Herzfeld; J. Maslanik; R.B. Lammers; M.A. Rawlins; C.J. Vorosmarty; T.S. Rupp; W. Wu; M. Calef

2008-01-01

The primary goal of the Western Arctic Linkage Experiment (WALE) was to better understand uncertainties of simulated hydrologic and ecosystem dynamics of the western Arctic in the context of 1) uncertainties in the data available to drive the models and 2) different approaches to simulating regional hydrology and ecosystem dynamics. Analyses of datasets on climate...

Tribal experiences and lessons learned in riparian ecosystem restoration

Treesearch

Ronald K. Miller; James E. Enote; Cameron L. Martinez

1996-01-01

Riparian ecosystems have been part of the culture of land use of native peoples in the Southwest United States for thousands of years. The experiences of tribal riparian initiatives to incorporate modern elements of environment and development with cultural needs are relatively few. This paper describes tribal case examples and approaches in riparian management which...

Vegetation of the Glacier Lakes Ecosystem Experiments Site

Treesearch

Claudia M. Regan; Robert C. Musselman; June D. Haines

1997-01-01

Vegetation at the Glacier Lakes Ecosystem Experiment Site, a 600 ha research site at 3200 to 3500 m elevation in the Snowy Range of southeastern Wyoming, was categorized and described from an intensive sampling of species abundances. A total of 304 vascular plant taxa were identified through collection and herbarium documentation. Plots with tree species were separated...

Science in the hardwood ecosystem experiment: accomplishments and the road ahead

Treesearch

Michael R. Saunders; Robert K. Swihart

2013-01-01

Over the next century, the Hardwood Ecosystem Experiment (HEE) in Indiana will provide numerous opportunities for collaborative research on how forest management affects the ecological, economic, and social resources of southern Indiana. Here, we highlight the pre-treatment research conducted at the HEE sites from 2006 through 2008 and discuss the role that pre-...

The hardwood ecosystem experiment: extension and outreach

Treesearch

Brian J. MacGowan; Lenny D. Farlee; Robert N. Chapman

2013-01-01

The Hardwood Ecosystem Experiment (HEE) in Indiana is a long-term, large-scale experimental study of forest management and its impacts on plants and animals. Information from the HEE should and will be made available to a diverse group of potential users. This paper summarizes educational efforts during the pre-treatment period and highlights potential mechanisms and...

The dilemma of controlling cultural eutrophication of lakes

PubMed Central

Schindler, David W.

2012-01-01

The management of eutrophication has been impeded by reliance on short-term experimental additions of nutrients to bottles and mesocosms. These measures of proximate nutrient limitation fail to account for the gradual changes in biogeochemical nutrient cycles and nutrient fluxes from sediments, and succession of communities that are important components of whole-ecosystem responses. Erroneous assumptions about ecosystem processes and lack of accounting for hysteresis during lake recovery have further confused management of eutrophication. I conclude that long-term, whole-ecosystem experiments and case histories of lake recovery provide the only reliable evidence for policies to reduce eutrophication. The only method that has had proven success in reducing the eutrophication of lakes is reducing input of phosphorus. There are no case histories or long-term ecosystem-scale experiments to support recent claims that to reduce eutrophication of lakes, nitrogen must be controlled instead of or in addition to phosphorus. Before expensive policies to reduce nitrogen input are implemented, they require ecosystem-scale verification. The recent claim that the ‘phosphorus paradigm’ for recovering lakes from eutrophication has been ‘eroded’ has no basis. Instead, the case for phosphorus control has been strengthened by numerous case histories and large-scale experiments spanning several decades. PMID:22915669

Combining paleo-data and modern exclosure experiments to assess the impact of megafauna extinctions on woody vegetation

PubMed Central

Bakker, Elisabeth S.; Gill, Jacquelyn L.; Johnson, Christopher N.; Vera, Frans W. M.; Sandom, Christopher J.; Asner, Gregory P.; Svenning, Jens-Christian

2016-01-01

Until recently in Earth history, very large herbivores (mammoths, ground sloths, diprotodons, and many others) occurred in most of the World’s terrestrial ecosystems, but the majority have gone extinct as part of the late-Quaternary extinctions. How has this large-scale removal of large herbivores affected landscape structure and ecosystem functioning? In this review, we combine paleo-data with information from modern exclosure experiments to assess the impact of large herbivores (and their disappearance) on woody species, landscape structure, and ecosystem functions. In modern landscapes characterized by intense herbivory, woody plants can persist by defending themselves or by association with defended species, can persist by growing in places that are physically inaccessible to herbivores, or can persist where high predator activity limits foraging by herbivores. At the landscape scale, different herbivore densities and assemblages may result in dynamic gradients in woody cover. The late-Quaternary extinctions were natural experiments in large-herbivore removal; the paleoecological record shows evidence of widespread changes in community composition and ecosystem structure and function, consistent with modern exclosure experiments. We propose a conceptual framework that describes the impact of large herbivores on woody plant abundance mediated by herbivore diversity and density, predicting that herbivore suppression of woody plants is strongest where herbivore diversity is high. We conclude that the decline of large herbivores induces major alterations in landscape structure and ecosystem functions. PMID:26504223

Combining paleo-data and modern exclosure experiments to assess the impact of megafauna extinctions on woody vegetation.

PubMed

Bakker, Elisabeth S; Gill, Jacquelyn L; Johnson, Christopher N; Vera, Frans W M; Sandom, Christopher J; Asner, Gregory P; Svenning, Jens-Christian

2016-01-26

Until recently in Earth history, very large herbivores (mammoths, ground sloths, diprotodons, and many others) occurred in most of the World's terrestrial ecosystems, but the majority have gone extinct as part of the late-Quaternary extinctions. How has this large-scale removal of large herbivores affected landscape structure and ecosystem functioning? In this review, we combine paleo-data with information from modern exclosure experiments to assess the impact of large herbivores (and their disappearance) on woody species, landscape structure, and ecosystem functions. In modern landscapes characterized by intense herbivory, woody plants can persist by defending themselves or by association with defended species, can persist by growing in places that are physically inaccessible to herbivores, or can persist where high predator activity limits foraging by herbivores. At the landscape scale, different herbivore densities and assemblages may result in dynamic gradients in woody cover. The late-Quaternary extinctions were natural experiments in large-herbivore removal; the paleoecological record shows evidence of widespread changes in community composition and ecosystem structure and function, consistent with modern exclosure experiments. We propose a conceptual framework that describes the impact of large herbivores on woody plant abundance mediated by herbivore diversity and density, predicting that herbivore suppression of woody plants is strongest where herbivore diversity is high. We conclude that the decline of large herbivores induces major alterations in landscape structure and ecosystem functions.

The development and succession of microbial communities in 90-day Bioregenerative Life Support Experiment in the Lunar Palace 1

NASA Astrophysics Data System (ADS)

Sun, Yi; Liu, Hong; Fu, Yuming; Liu, Bojie; Su, Qiang; Xie, Beizhen; Qin, Youcai; Dong, Chen; Liu, Guanghui

Lunar Palace 1, as an integrative experiment facility for permanent astrobase life-support artificial closed ecosystem, is an artificial ecosystem which consists of plant cultivation, animal breeding and waste treatment units. It has been used to carry out a 90-day bioregenerative life support experiment with three crew members. Apparently, it’s hard to prevent the growth of microorganisms in such closed ecosystem for their strong adaptive capacity. Original microorganisms in the cabin, microbes in the course of loads delivery and the autologous microorganism by crew members and animals themselves are all the main source of the interior microorganisms, which may grow and regenerate in air, water and plants. Therefore, if these microorganisms could not be effectively monitored and controlled, it may cause microbial contamination and even lead to the unsteadiness of the whole closed ecosystem. In this study, the development and succession of the microbial communities of air, water system, plant system, and key facilities surfaces in Lunar Palace 1 were continuously monitored and analyzed by using plate counting method and molecular biological method during the 90-day experiment. The results were quite useful for the controlling of internal microorganisms and the safe operation of the whole system, and could also reveal the succession rules of microorganisms in an artificial closed ecosystem.

Hydrocentric view of Agro-ecosystem Resiliency to Extreme Hydrometeorological and Climate Events in the High Plains, US.

NASA Astrophysics Data System (ADS)

Munoz-Arriola, Francisco; Sharma, Ashutosh; Werner, Katherine; Chacon, Juan-Carlos; Corzo, Gerald; Goyal, Manish-Kumar

2017-04-01

An increasing incidence of Hydrometeorological and Climate Extreme Events (EHCEs) is challenging food, water, and ecosystem services security at local to global contexts. This study aims to understand how a large-scale representation of agroecosystems and ecosystems respond to EHCE in the Northern Highplains, US. To track such responses the Variable Infiltration Capacity model (VIC) Land Surface Hydrology model was used and two experiments were implemented. The first experiment uses the LAI MODIS15A2 product to capture dynamic responses of vegetation with a time span from 2000 to 2013. The second experiment used a climatological fixed seasonal cycle calculated as the average from the 2000-2013 dynamic MODIS15A2 product to isolate vegetation from soil physical responses. Based on the analyses of multiple hydrological variables and state variables and high-level organization of agroecosystems and ecosystems, we evidence how the influence of droughts and anomalously wet conditions affect hydrological resilience at large scale.

Nutrient resorption and patterns of litter production and decomposition in a Neotropical savanna.

Treesearch

A.R. Kozovits; M.M.C. Bustamante; C.R. Garofalo; S. Bucci; A.C. Franco; G. Goldstein; F. Meinzer

2007-01-01

1. Deposition of nutrients owing to anthropogenic activities has the potential to change nutrient availability in nutrient-limited ecosystems with consequences for plant and ecosystem processes. 2. Species-specific and ecosystem responses to the addition of nutrients were studied in a field experiment conducted in a Savanna (Cerrado sensu stricto)...

Multiscale socioeconomic assessment across large ecosystems: lessons from practice

Treesearch

Rebecca J. McLain; Ellen M. Donoghue; Jonathan Kusel; Lita Buttolph; Susan Charnley

2008-01-01

Implementation of ecosystem management projects has created a demand for socioeconomic assessments to predict or evaluate the impacts of ecosystem policies. Social scientists for these assessments face challenges that, although not unique to such projects, are more likely to arise than in smaller scale ones. This article summarizes lessons from our experiences with...

Guided Inquiry Learning Unit on Aquatic Ecosystems for Seventh Grade Students

ERIC Educational Resources Information Center

To-im, Jongdee; Ruenwongsa, Pintip

2009-01-01

Using mini-aquaria experiments, a learning unit on the effects of light period on aquatic ecosystems was developed for 7th grade students. This guided inquiry unit was aimed at helping students understand basic ecological principles involved in relationships among physical, chemical, and biological components in aquatic ecosystems. It involved…

Suppression of savanna ants alters invertebrate composition and influences key ecosystem processes.

PubMed

Parr, C L; Eggleton, P; Davies, A B; Evans, T A; Holdsworth, S

2016-06-01

In almost every ecosystem, ants (Hymenoptera: Formicidae) are the dominant terrestrial invertebrate group. Their functional value was highlighted by Wilson (1987) who famously declared that invertebrates are the "little things that run the world." However, while it is generally accepted that ants fulfil important functions, few studies have tested these assumptions and demonstrated what happens in their absence. We report on a novel large-scale field experiment in undisturbed savanna habitat where we examined how ants influence the abundance of other invertebrate taxa in the system, and affect the key processes of decomposition and herbivory. Our experiment demonstrated that ants suppressed the abundance and activity of beetles, millipedes, and termites, and also influenced decomposition rates and levels of herbivory. Our study is the first to show that top-down control of termites by ants can have important ecosystem consequences. Further studies are needed to elucidate the effects ant communities have on other aspects of the ecosystem (e.g., soils, nutrient cycling, the microbial community) and how their relative importance for ecosystem function varies among ecosystem types (e.g., savanna vs. forest).

Threshold responses to interacting global changes in a California grassland ecosystem

DOE Office of Scientific and Technical Information (OSTI.GOV)

Field, Christopher; Mooney, Harold; Vitousek, Peter

2015-02-02

Building on the history and infrastructure of the Jasper Ridge Global Change Experiment, we conducted experiments to explore the potential for single and combined global changes to stimulate fundamental type changes in ecosystems that start the experiment as California annual grassland. Using a carefully orchestrated set of seedling introductions, followed by careful study and later removal, the grassland was poised to enable two major kinds of transitions that occur in real life and that have major implications for ecosystem structure, function, and services. These are transitions from grassland to shrubland/forest and grassland to thistle patch. The experiment took place inmore » the context of 4 global change factors – warming, elevated CO 2, N deposition, and increased precipitation – in a full-factorial array, present as all possible 1, 2, 3, and 4-factor combinations, with each combination replicated 8 times.« less

Advancing biodiversity-ecosystem functioning science using high-density tree-based experiments over functional diversity gradients.

PubMed

Tobner, Cornelia M; Paquette, Alain; Reich, Peter B; Gravel, Dominique; Messier, Christian

2014-03-01

Increasing concern about loss of biodiversity and its effects on ecosystem functioning has triggered a series of manipulative experiments worldwide, which have demonstrated a general trend for ecosystem functioning to increase with diversity. General mechanisms proposed to explain diversity effects include complementary resource use and invoke a key role for species' functional traits. The actual mechanisms by which complementary resource use occurs remain, however, poorly understood, as well as whether they apply to tree-dominated ecosystems. Here we present an experimental approach offering multiple innovative aspects to the field of biodiversity-ecosystem functioning (BEF) research. The International Diversity Experiment Network with Trees (IDENT) allows research to be conducted at several hierarchical levels within individuals, neighborhoods, and communities. The network investigates questions related to intraspecific trait variation, complementarity, and environmental stress. The goal of IDENT is to identify some of the mechanisms through which individuals and species interact to promote coexistence and the complementary use of resources. IDENT includes several implemented and planned sites in North America and Europe, and uses a replicated design of high-density tree plots of fixed species-richness levels varying in functional diversity (FD). The design reduces the space and time needed for trees to interact allowing a thorough set of mixtures varying over different diversity gradients (specific, functional, phylogenetic) and environmental conditions (e.g., water stress) to be tested in the field. The intention of this paper is to share the experience in designing FD-focused BEF experiments with trees, to favor collaborations and expand the network to different conditions.

Pushing precipitation to the extremes in distributed experiments: Recommendations for simulating wet and dry years

USGS Publications Warehouse

Knapp, Alan K.; Avolio, Meghan L.; Beier, Claus; Carroll, Charles J.W.; Collins, Scott L.; Dukes, Jeffrey S.; Fraser, Lauchlan H.; Griffin-Nolan, Robert J.; Hoover, David L.; Jentsch, Anke; Loik, Michael E.; Phillips, Richard P.; Post, Alison K.; Sala, Osvaldo E.; Slette, Ingrid J.; Yahdjian, Laura; Smith, Melinda D.

2017-01-01

Intensification of the global hydrological cycle, ranging from larger individual precipitation events to more extreme multiyear droughts, has the potential to cause widespread alterations in ecosystem structure and function. With evidence that the incidence of extreme precipitation years (defined statistically from historical precipitation records) is increasing, there is a clear need to identify ecosystems that are most vulnerable to these changes and understand why some ecosystems are more sensitive to extremes than others. To date, opportunistic studies of naturally occurring extreme precipitation years, combined with results from a relatively small number of experiments, have provided limited mechanistic understanding of differences in ecosystem sensitivity, suggesting that new approaches are needed. Coordinated distributed experiments (CDEs) arrayed across multiple ecosystem types and focused on water can enhance our understanding of differential ecosystem sensitivity to precipitation extremes, but there are many design challenges to overcome (e.g., cost, comparability, standardization). Here, we evaluate contemporary experimental approaches for manipulating precipitation under field conditions to inform the design of ‘Drought-Net’, a relatively low-cost CDE that simulates extreme precipitation years. A common method for imposing both dry and wet years is to alter each ambient precipitation event. We endorse this approach for imposing extreme precipitation years because it simultaneously alters other precipitation characteristics (i.e., event size) consistent with natural precipitation patterns. However, we do not advocate applying identical treatment levels at all sites – a common approach to standardization in CDEs. This is because precipitation variability varies >fivefold globally resulting in a wide range of ecosystem-specific thresholds for defining extreme precipitation years. For CDEs focused on precipitation extremes, treatments should be based on each site's past climatic characteristics. This approach, though not often used by ecologists, allows ecological responses to be directly compared across disparate ecosystems and climates, facilitating process-level understanding of ecosystem sensitivity to precipitation extremes.

Pushing precipitation to the extremes in distributed experiments: recommendations for simulating wet and dry years.

PubMed

Knapp, Alan K; Avolio, Meghan L; Beier, Claus; Carroll, Charles J W; Collins, Scott L; Dukes, Jeffrey S; Fraser, Lauchlan H; Griffin-Nolan, Robert J; Hoover, David L; Jentsch, Anke; Loik, Michael E; Phillips, Richard P; Post, Alison K; Sala, Osvaldo E; Slette, Ingrid J; Yahdjian, Laura; Smith, Melinda D

2017-05-01

Intensification of the global hydrological cycle, ranging from larger individual precipitation events to more extreme multiyear droughts, has the potential to cause widespread alterations in ecosystem structure and function. With evidence that the incidence of extreme precipitation years (defined statistically from historical precipitation records) is increasing, there is a clear need to identify ecosystems that are most vulnerable to these changes and understand why some ecosystems are more sensitive to extremes than others. To date, opportunistic studies of naturally occurring extreme precipitation years, combined with results from a relatively small number of experiments, have provided limited mechanistic understanding of differences in ecosystem sensitivity, suggesting that new approaches are needed. Coordinated distributed experiments (CDEs) arrayed across multiple ecosystem types and focused on water can enhance our understanding of differential ecosystem sensitivity to precipitation extremes, but there are many design challenges to overcome (e.g., cost, comparability, standardization). Here, we evaluate contemporary experimental approaches for manipulating precipitation under field conditions to inform the design of 'Drought-Net', a relatively low-cost CDE that simulates extreme precipitation years. A common method for imposing both dry and wet years is to alter each ambient precipitation event. We endorse this approach for imposing extreme precipitation years because it simultaneously alters other precipitation characteristics (i.e., event size) consistent with natural precipitation patterns. However, we do not advocate applying identical treatment levels at all sites - a common approach to standardization in CDEs. This is because precipitation variability varies >fivefold globally resulting in a wide range of ecosystem-specific thresholds for defining extreme precipitation years. For CDEs focused on precipitation extremes, treatments should be based on each site's past climatic characteristics. This approach, though not often used by ecologists, allows ecological responses to be directly compared across disparate ecosystems and climates, facilitating process-level understanding of ecosystem sensitivity to precipitation extremes. © 2016 John Wiley & Sons Ltd.

Ecological restoration experiments (1992-2007) at the G.A. Pearson Natural Area, Fort Valley Experimental Forest (P-53)

Treesearch

Margaret M. Moore; Wallace Covington; Peter Z. Fulé; Stephen C. Hart; Thomas E. Kolb; Joy N. Mast; Stephen S. Sackett; Michael R. Wagner

2008-01-01

In 1992 an experiment was initiated at the G. A. Pearson Natural Area on the Fort Valley Experimental Forest to evaluate long-term ecosystem responses to two restoration treatments: thinning only and thinning with prescribed burning. Fifteen years of key findings about tree physiology, herbaceous, and ecosystem responses are presented.

Missouri Ozark Forest Ecosystem Project: site history, soils, landforms, woody and herbaceous vegetation, down wood, and inventory methods for the landscape experiment.

Treesearch

Stephen R. Shifley; Brian L., eds. Brookshire

2000-01-01

Describes vegetation and physical site conditions at the initiation (1991-1995) of the Missouri Ozark Forest Ecosystem Project (MOFEP) in the southeastern Missouri Ozarks. Provides detailed information on sampling protocols and summarizes initial conditions of the landscape experiment prior to harvest treatments. Summaries are by plot, by ~800-acre...

Spatial ecology and behavior of eastern box turtles on the hardwood ecosystem experiment: pre-treatment results

Treesearch

Andrea F. Currylow; Brian J. MacGowan; Rod N. Williams

2013-01-01

To understand better how eastern box turtles (Terrapene carolina carolina) are affected by forest management practices, we monitored movements of box turtles prior to silvicultural treatments within the Hardwood Ecosystem Experiment (HEE) in Indiana. During 2007 and 2008, we tracked 23-28 turtles on six units of the HEE. Estimated minimum convex...

Prognosis for ecosystem recovery following rodent eradication and seabird restoration in an island archipelago.

PubMed

Jones, Holly P

2010-07-01

Invasive species are widespread and can have devastating effects on biota, especially insular biota. Invasive species eradications are increasingly employed to promote island recovery to preinvasion states. However, it remains unclear if additional restoration actions may be required on islands that were once heavily reliant on seabird guano for ecosystem functions. Active seabird augmentation has been suggested as necessary to exact ecosystem recovery on contemporary timescales in some cases. I use two experiments on offshore islands in Cook Strait, New Zealand, to test the hypothesis that seabird restoration will restore island ecosystem functioning following invasive rodent removal. The first is a small-scale single-island fertilization experiment that simulates seabird recovery. This experiment tested the recovery potential of offshore islands and was used to infer the density of seabirds needed to elicit ecosystem recovery. The second is a large-scale natural experiment that takes advantage of eight islands with differing rodent eradication and seabird restoration histories. I compared ecosystem functioning variables (delta 15N, C:N ratios in soil, plants, and spiders, as well as arthropod abundance and diversity) on two islands that had rodents eradicated and two islands undergoing seabird augmentation with two control islands (never invaded by rodents) and two positive control islands (currently invaded by rodents). The results suggest that islands do have the potential for recovery given nutrient amendments, but that islands with rodents eradicated and islands undergoing seabird augmentation have not recovered most of their ecosystem function. Finer, intra-island analysis showed that seabird restoration projects have the potential to speed the recovery process, but that the projects on the studied seabird restoration islands were not advanced enough to produce island-wide recovery. The results suggest that high seabird densities (5-10 burrows/m2) are needed to promote recovery to never-invaded control levels. Seabird augmentation, through chick translocation and/or social facilitation with decoys, vocalization playbacks, and/or mirrors can supplement passive seabird recovery on islands where seabirds have been extirpated or extremely reduced by invasive predators. Such restoration efforts may be necessary to promote ecosystem recovery on contemporary timescales.

Tropical forest response to elevated CO2: Model-experiment integration at the AmazonFACE site.

NASA Astrophysics Data System (ADS)

Frankenberg, C.; Berry, J. A.; Guanter, L.; Joiner, J.

2014-12-01

The terrestrial biosphere's response to current and future elevated atmospheric carbon dioxide (eCO2) is a large source of uncertainty in future projections of the C cycle, climate and ecosystem functioning. In particular, the sensitivity of tropical rainforest ecosystems to eCO­2 is largely unknown even though the importance of tropical forests for biodiversity, carbon storage and regional and global climate feedbacks is unambiguously recognized. The AmazonFACE (Free-Air Carbon Enrichment) project will be the first ecosystem scale eCO2 experiment undertaken in the tropics, as well as the first to be undertaken in a mature forest. AmazonFACE provides the opportunity to integrate ecosystem modeling with experimental observations right from the beginning of the experiment, harboring a two-way exchange, i.e. models provide hypotheses to be tested, and observations deliver the crucial data to test and improve ecosystem models. We present preliminary exploration of observed and expected process responses to eCO2 at the AmazonFACE site from the dynamic global vegetation model LPJ-GUESS, highlighting opportunities and pitfalls for model integration of tropical FACE experiments. The preliminary analysis provides baseline hypotheses, which are to be further developed with a follow-up multiple model inter-comparison. The analysis builds on the recently undertaken FACE-MDS (Model-Data Synthesis) project, which was applied to two temperate FACE experiments and exceeds the traditional focus on comparing modeled end-target output. The approach has proven successful in identifying well (and less well) represented processes in models, which are separated for six clusters also here; (1) Carbon fluxes, (2) Carbon pools, (3) Energy balance, (4) Hydrology, (5) Nutrient cycling, and (6) Population dynamics. Simulation performance of observed conditions at the AmazonFACE site (a.o. from Manaus K34 eddy flux tower) will highlight process-based model deficiencies, and aid the separation of uncertainties arising from general ecosystem responses and those responses related to eCO2.

Tropical forest response to elevated CO2: Model-experiment integration at the AmazonFACE site.

NASA Astrophysics Data System (ADS)

Fleischer, K.

2015-12-01

The terrestrial biosphere's response to current and future elevated atmospheric carbon dioxide (eCO2) is a large source of uncertainty in future projections of the C cycle, climate and ecosystem functioning. In particular, the sensitivity of tropical rainforest ecosystems to eCO­2 is largely unknown even though the importance of tropical forests for biodiversity, carbon storage and regional and global climate feedbacks is unambiguously recognized. The AmazonFACE (Free-Air Carbon Enrichment) project will be the first ecosystem scale eCO2 experiment undertaken in the tropics, as well as the first to be undertaken in a mature forest. AmazonFACE provides the opportunity to integrate ecosystem modeling with experimental observations right from the beginning of the experiment, harboring a two-way exchange, i.e. models provide hypotheses to be tested, and observations deliver the crucial data to test and improve ecosystem models. We present preliminary exploration of observed and expected process responses to eCO2 at the AmazonFACE site from the dynamic global vegetation model LPJ-GUESS, highlighting opportunities and pitfalls for model integration of tropical FACE experiments. The preliminary analysis provides baseline hypotheses, which are to be further developed with a follow-up multiple model inter-comparison. The analysis builds on the recently undertaken FACE-MDS (Model-Data Synthesis) project, which was applied to two temperate FACE experiments and exceeds the traditional focus on comparing modeled end-target output. The approach has proven successful in identifying well (and less well) represented processes in models, which are separated for six clusters also here; (1) Carbon fluxes, (2) Carbon pools, (3) Energy balance, (4) Hydrology, (5) Nutrient cycling, and (6) Population dynamics. Simulation performance of observed conditions at the AmazonFACE site (a.o. from Manaus K34 eddy flux tower) will highlight process-based model deficiencies, and aid the separation of uncertainties arising from general ecosystem responses and those responses related to eCO2.

Lessons from forest FACE experiments provide guidance for Amazon-FACE science plan (Invited)

NASA Astrophysics Data System (ADS)

Norby, R. J.; Lapola, D. M.

2013-12-01

Free-air CO2 enrichment (FACE) experiments have provided novel insights into the ecological mechanisms controlling the cycling and storage of carbon in terrestrial ecosystems, and they provide a strong foundation for next-generation experiments in unexplored biomes. Specific lessons from FACE experiments include: (1) Carbon cycle responses are time-dependent because component processes have different rate constants: for example, net primary productivity is increased by elevated CO2, but the response may diminish with time as N cycling feedbacks become important. (2) Carbon partitioning patterns determine the fate of the extra C taken up by CO2-enriched plants, but partitioning responses remain an important challenge for ecosystem models. (3) The influence of N cycling on plant and ecosystem C cycling continues to be a critical uncertainty, and new experiments, especially in the tropics, must also consider P cycling. (4) Plant community structure can influence the ecosystem response to elevated CO2, but dynamic vegetation effects have not been adequately addressed. These experiences from FACE experiments in temperate forests are now guiding the development of a science plan for a FACE experiment in Amazonia. Models and small-scale experimental results agree that elevated CO2 will affect the metabolism of tropical ecosystems, but the qualitative and quantitative expression of the effects are largely unknown, representing a major source of uncertainty that limits our capacity to assess the vulnerability of the Amazon forest to climate change. Recognizing the high importance of the forests of the Amazon basin on global carbon, water, and energy cycles, biodiversity conservation, and the provision of essential services in Latin America, a consortium of Brazilian researchers and international collaborators have developed a science plan for Amazon-FACE. While the challenges presented both by infrastructure needs (roads, electricity, and provision of CO2) and biology (the size and diversity of the forest) are substantial, preliminary evaluation and past experience from temperate forest FACE experiments have supported the feasibility of an experiment comprising replicated 30-m diameter FACE plots in primary forest. The proposed site is the ZF2 research area 60 km north of Manaus and administered by Brazil's National Institute for Amazonia Research (INPA). The vegetation is representative of a dominant fraction of the forests occurring in the Amazon basin: old-growth closed-canopy terra firme (non-flooded) forest with trees 30-35 m in height on well drained clay soils. The major science questions guiding the experiment are closely informed by results of past FACE experiment and involve carbon metabolism, water use, nutrient cycling, interactions with environmental stressors, and the relationship between plant functional traits and community composition. FACE experiments can define ecological processes and mechanisms of responses for predictive models of ecosystem response, and models of CO2 response can define critical uncertainties and testable hypotheses for experiments; hence, the Amazon FACE experiment will feature a close integration of modeling and experimental approaches.

Nutrient Dynamics in Riparian Ecosystems. Chapter 6 in Riparian Ecosystems, Volume 1: Science Synthesis and Management Implications

EPA Science Inventory

This report will be a chapter in an updated Riparian BMP manual developed by the State of WA Fish and Wildlife Dept. Jana Compton and I were asked to contribute the chapter on nutrients in riparian ecosystems based on experience and research in riparian systems. The document is...

Moving beyond the exchange value in the nonmarket valuation of ecosystem services

Treesearch

Karen E. Allen; Rebecca Moore

2016-01-01

There has been much discussion across the ecosystem services literature as to the role of economic valuation in identifying ecosystem service values and shaping policy. This article demonstrates a non-typical use of a nonmarket valuation technique known as the stated choice experiment (CE) for understanding a range of public preferences for stream-related...

Alternative silvicultural practices in Appalachian forest ecosystems: implications for species diversity, ecosystem resilience, and commercial timber production

Treesearch

Thomas R. Fox; Carola A. Haas; David W. Smith; David L. Loftis; Shepard M. Zedaker; Robert H. Jones; A.L. Hammett

2007-01-01

Increasing demands for timber and non-timber forest products often conflict with demands to maintain biodiversity and ecosystem processes. To examine tradeoffs between these goals, we implemented six alternative management systems using a stand-level, replicated experiment. The treatments included four silvicultural regeneration methods designed to sustain timber...

Scaling ozone responses of forest trees to the ecosystem level in a changing climate

Treesearch

D.F. Karnosky; K.S. Pregitzer; D.R. Zak; M.E. Kubiske; G.R. Hendrey; D. Weinstein; M. Nosal; K.E. Percy

2005-01-01

Many uncertainties remain regarding how climate change will alter the structure and function of forest ecosystems. At the Aspen FACE experiment in northern Wisconsin, we are attempting to understand how an aspen/birch/maple forest ecosystem responds to long-term exposure to elevated carbon dioxide (CO2) and ozone (O3),...

Ecosystem carbon storage does not vary with increasing mean annual temperature in Hawaiian tropical montane wet forests

Treesearch

Paul Selmants; Creighton Litton; Christian P. Giardina; Greg P. Asner

2014-01-01

Theory and experiment agree that climate warming will increase carbon fluxes between terrestrial ecosystems and the atmosphere. The effect of this increased exchange on terrestrial carbon storage is less predictable, with important implications for potential feedbacks to the climate system. We quantified how increased mean annual temperature (MAT) affects ecosystem...

Establishment and Data Collection of Vegetation-related Studies on the Missouri Ozark Forest Ecosystem Project Study Sites

Treesearch

Brian L. Brookshire; Daniel C. Dey

2000-01-01

The Missouri Ozark Forest Ecosystem Project (MOFEP) is an experiment designed to determine the effects of forest management practices on important ecosystem attributes. MOFEP treatments evaluated include even-aged, uneven-aged, and no management treatments. Forest vegetation provides a common ecological link among many organisms and ecological processes, and therefore...

Commentary: Urgent need for large-scale warming manipulation experiments in tropical forests

NASA Astrophysics Data System (ADS)

Cavaleri, M. A.; Wood, T. E.; Reed, S.

2013-12-01

Tropical forests represent the largest fluxes of carbon into and out of the atmosphere of any terrestrial ecosystem type on earth. Despite their clear biogeochemical importance, responses of tropical forests to global warming are more uncertain than for any other biome. This uncertainty stems primarily from a lack of mechanistic data, in part because warming manipulation field experiments have been located almost exclusively in higher latitude systems. As a result of the large fluxes, lack of data, and high uncertainty, recent studies have highlighted the tropics as a 'high priority region' for future climate change research. We argue that warming manipulation experiments are urgently needed in tropical forests that are: 1) single-factor, 2) large-scale, and 3) long-term. The emergence of a novel heat regime is predicted for the tropics within the next two decades, and tropical forest trees may be more susceptible to warming than previously thought. Over a decade of Free Air CO2 Enrichment experiments have shown that single-factor studies that integrate above- and belowground function can be the most informative and efficient means of informing models, which can then be used to determine interactive effects of multiple factors. Warming both above- and below-ground parts of an ecosystem would be fundamental to the understanding of whole-ecosystem and net carbon responses because of the multiple feedbacks between tree canopy, root, and soil function. Finally, evidence from high-latitude warming experiments highlight the importance of long-term studies by suggesting that key processes related to carbon cycling, like soil respiration, could acclimate with extended warming. Despite the fact that there has never been a long-term ecosystem-level warming experiment in any forest, the technology is available, and momentum is gathering. In order to study the effects of warming on tropical forests, which contribute disproportionately to global carbon balance, full-scale ecosystem warming experiments are imperative.

Rising tides, cumulative impacts and cascading changes to estuarine ecosystem functions.

PubMed

O'Meara, Theresa A; Hillman, Jenny R; Thrush, Simon F

2017-08-31

In coastal ecosystems, climate change affects multiple environmental factors, yet most predictive models are based on simple cause-and-effect relationships. Multiple stressor scenarios are difficult to predict because they can create a ripple effect through networked ecosystem functions. Estuarine ecosystem function relies on an interconnected network of physical and biological processes. Estuarine habitats play critical roles in service provision and represent global hotspots for organic matter processing, nutrient cycling and primary production. Within these systems, we predicted functional changes in the impacts of land-based stressors, mediated by changing light climate and sediment permeability. Our in-situ field experiment manipulated sea level, nutrient supply, and mud content. We used these stressors to determine how interacting environmental stressors influence ecosystem function and compared results with data collected along elevation gradients to substitute space for time. We show non-linear, multi-stressor effects deconstruct networks governing ecosystem function. Sea level rise altered nutrient processing and impacted broader estuarine services ameliorating nutrient and sediment pollution. Our experiment demonstrates how the relationships between nutrient processing and biological/physical controls degrade with environmental stress. Our results emphasise the importance of moving beyond simple physically-forced relationships to assess consequences of climate change in the context of ecosystem interactions and multiple stressors.

Consistent effects of biodiversity loss on multifunctionality across contrasting ecosystems.

PubMed

Fanin, Nicolas; Gundale, Michael J; Farrell, Mark; Ciobanu, Marcel; Baldock, Jeff A; Nilsson, Marie-Charlotte; Kardol, Paul; Wardle, David A

2018-02-01

Understanding how loss of biodiversity affects ecosystem functioning, and thus the delivery of ecosystem goods and services, has become increasingly necessary in a changing world. Considerable recent attention has focused on predicting how biodiversity loss simultaneously impacts multiple ecosystem functions (that is, ecosystem multifunctionality), but the ways in which these effects vary across ecosystems remain unclear. Here, we report the results of two 19-year plant diversity manipulation experiments, each established across a strong environmental gradient. Although the effects of plant and associated fungal diversity loss on individual functions frequently differed among ecosystems, the consequences of biodiversity loss for multifunctionality were relatively invariant. However, the context-dependency of biodiversity effects also worked in opposing directions for different individual functions, meaning that similar multifunctionality values across contrasting ecosystems could potentially mask important differences in the effects of biodiversity on functioning among ecosystems. Our findings highlight that an understanding of the relative contribution of species or functional groups to individual ecosystem functions among contrasting ecosystems and their interactions (that is, complementarity versus competition) is critical for guiding management efforts aimed at maintaining ecosystem multifunctionality and the delivery of multiple ecosystem services.

Temporal and Spatial Variation in Peatland Carbon Cycling and Implications for Interpreting Responses of an Ecosystem-Scale Warming Experiment

Treesearch

Natalie A. Griffiths; Paul J. Hanson; Daniel M. Ricciuto; Colleen M. Iversen; Anna M. Jensen; Avni Malhotra; Karis J. McFarlane; Richard J. Norby; Khachik Sargsyan; Stephen D. Sebestyen; Xiaoying Shi; Anthony P. Walker; Eric J. Ward; Jeffrey M. Warren; David J. Weston

2017-01-01

We are conducting a large-scale, long-term climate change response experiment in an ombrotrophic peat bog in Minnesota to evaluate the effects of warming and elevated CO2 on ecosystem processes using empirical and modeling approaches. To better frame future assessments of peatland responses to climate change, we characterized and compared spatial...

Local adaptation in Trinidadian guppies alters stream ecosystem structure at landscape scales despite high environmental variability

USGS Publications Warehouse

Simon, Troy N.; Bassar, Ronald D.; Binderup, Andrew J.; Flecker, Alex S.; Freeman, Mary C.; Gilliam, James F.; Marshall, Michael C.; Thomas, Steve A.; Travis, Joseph; Reznick, David N.; Pringle, Catherine M.

2017-01-01

While previous studies have shown that evolutionary divergence alters ecological processes in small-scale experiments, a major challenge is to assess whether such evolutionary effects are important in natural ecosystems at larger spatial scales. At the landscape scale, across eight streams in the Caroni drainage, we found that the presence of locally adapted populations of guppies (Poecilia reticulata) is associated with reduced algal biomass and increased invertebrate biomass, while the opposite trends were true in streams with experimentally introduced populations of non-locally adapted guppies. Exclusion experiments conducted in two separate reaches of a single stream showed that guppies with locally adapted phenotypes significantly reduced algae with no effect on invertebrates, while non-adapted guppies had no effect on algae but significantly reduced invertebrates. These divergent effects of phenotype on stream ecosystems are comparable in strength to the effects of abiotic factors (e.g., light) known to be important drivers of ecosystem condition. They also corroborate the results of previous experiments conducted in artificial streams. Our results demonstrate that local adaptation can produce phenotypes with significantly different effects in natural ecosystems at a landscape scale, within a tropical watershed, despite high variability in abiotic factors: five of the seven physical and chemical parameters measured across the eight study streams varied by more than one order of magnitude. Our findings suggest that ecosystem structure is, in part, an evolutionary product and not simply an ecological pattern.

Assimilation of satellite color observations in a coupled ocean GCM-ecosystem model

NASA Technical Reports Server (NTRS)

Sarmiento, Jorge L.

1992-01-01

Monthly average coastal zone color scanner (CZCS) estimates of chlorophyll concentration were assimilated into an ocean global circulation model(GCM) containing a simple model of the pelagic ecosystem. The assimilation was performed in the simplest possible manner, to allow the assessment of whether there were major problems with the ecosystem model or with the assimilation procedure. The current ecosystem model performed well in some regions, but failed in others to assimilate chlorophyll estimates without disrupting important ecosystem properties. This experiment gave insight into those properties of the ecosystem model that must be changed to allow data assimilation to be generally successful, while raising other important issues about the assimilation procedure.

Modeled effect of warming on ecosystem carbon and water dynamics within grassland/old-field ecosystems along a moisture gradient

USDA-ARS?s Scientific Manuscript database

As a consequence of steadily increasing concentrations of greenhouse gases in Earth’s atmosphere, average world-wide surface temperature is expected to increase 1.5-6.4°C by the end of the 21st Century. Results from manipulative field experiments and ecosystem modeling indicate that plants and soil...

Ecosystem vulnerability assessment and synthesis: a report from the Climate Change Response Framework Project in northern Wisconsin

Treesearch

Chris Swanston; Maria Janowiak; Louis Iverson; Linda Parker; David Mladenoff; Leslie Brandt; Patricia Butler; Matt St. Pierre; Anantha Prasad; Stephen Matthews; Matthew Peters; Dale Higgins; Avery Dorland

2011-01-01

The forests of northern Wisconsin will likely experience dramatic changes over the next 100 years as a result of climate change. This assessment evaluates key forest ecosystem vulnerabilities to climate change across northern Wisconsin under a range of future climate scenarios. Warmer temperatures and shifting precipitation patterns are expected to influence ecosystem...

Decadal responses in soil N dynamics at the Bear Brook Watershed in Maine, USA

Treesearch

Sultana Jefts; Ivan J. Fernandez; Lindwey E. Rustad; D. Bryan Dail

2004-01-01

Atmospheric nitrogen deposition to forested ecosystems is a concern because of both geochemical and biological consequences for ecosystem integrity. High levels of prolonged N deposition can lead to "N saturation" of the ecosystem. The Bear Brook Watershed in Maine is a long-term, paired forested watershed experiment with over a decade of experimental N...

Laser entertainment and light shows in education

NASA Astrophysics Data System (ADS)

Sabaratnam, Andrew T.; Symons, Charles

2002-05-01

Laser shows and beam effects have been a source of entertainment since its first public performance May 9, 1969, at Mills College in Oakland, California. Since 1997, the Photonics Center, NgeeAnn Polytechnic, Singapore, has been using laser shows as a teaching tool. Students are able to exhibit their creative skills and learn at the same time how lasers are used in the entertainment industry. Students will acquire a number of skills including handling three- phase power supply, operation of cooling system, and laser alignment. Students also acquire an appreciation of the arts, learning about shapes and contours as they develop graphics for the shows. After holography, laser show animation provides a combination of the arts and technology. This paper aims to briefly describe how a krypton-argon laser, galvanometer scanners, a polychromatic acousto-optic modulator and related electronics are put together to develop a laser projector. The paper also describes how students are trained to make their own laser animation and beam effects with music, and at the same time have an appreciation of the operation of a Class IV laser and the handling of optical components.

Common bacterial responses in six ecosystems exposed to 10 years of elevated atmospheric carbon dioxide.

PubMed

Dunbar, John; Eichorst, Stephanie A; Gallegos-Graves, La Verne; Silva, Shannon; Xie, Gary; Hengartner, N W; Evans, R David; Hungate, Bruce A; Jackson, Robert B; Megonigal, J Patrick; Schadt, Christopher W; Vilgalys, Rytas; Zak, Donald R; Kuske, Cheryl R

2012-05-01

Six terrestrial ecosystems in the USA were exposed to elevated atmospheric CO(2) in single or multifactorial experiments for more than a decade to assess potential impacts. We retrospectively assessed soil bacterial community responses in all six-field experiments and found ecosystem-specific and common patterns of soil bacterial community response to elevated CO(2) . Soil bacterial composition differed greatly across the six ecosystems. No common effect of elevated atmospheric CO(2) on bacterial biomass, richness and community composition across all of the ecosystems was identified, although significant responses were detected in individual ecosystems. The most striking common trend across the sites was a decrease of up to 3.5-fold in the relative abundance of Acidobacteria Group 1 bacteria in soils exposed to elevated CO(2) or other climate factors. The Acidobacteria Group 1 response observed in exploratory 16S rRNA gene clone library surveys was validated in one ecosystem by 100-fold deeper sequencing and semi-quantitative PCR assays. Collectively, the 16S rRNA gene sequencing approach revealed influences of elevated CO(2) on multiple ecosystems. Although few common trends across the ecosystems were detected in the small surveys, the trends may be harbingers of more substantive changes in less abundant, more sensitive taxa that can only be detected by deeper surveys. Representative bacterial 16S rRNA gene clone sequences were deposited in GenBank with Accession No. JQ366086–JQ387568. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.

Responses to canopy loss and debris deposition in a tropical forest ecosystem: Synthesis from an experimental manipulation simulating effects of hurricane disturbance

Treesearch

A.B. Shiels; Grizelle Gonzalez; M.R. Willig

2014-01-01

Hurricanes, cyclones, or typhoons are intense and broad-scale disturbances that affect many island and coastal ecosystems throughout the world. We summarize the findings of the articles that compose this special issue of Forest Ecology and Management, which focuses on a manipulative experiment (the Canopy Trimming Experiment, CTE) that simulates two key aspects of...

Millennial Climatic Fluctuations Are Key to the Structure of Last Glacial Ecosystems

PubMed Central

Huntley, Brian; Allen, Judy R. M.; Collingham, Yvonne C.; Hickler, Thomas; Lister, Adrian M.; Singarayer, Joy; Stuart, Anthony J.; Sykes, Martin T.; Valdes, Paul J.

2013-01-01

Whereas fossil evidence indicates extensive treeless vegetation and diverse grazing megafauna in Europe and northern Asia during the last glacial, experiments combining vegetation models and climate models have to-date simulated widespread persistence of trees. Resolving this conflict is key to understanding both last glacial ecosystems and extinction of most of the mega-herbivores. Using a dynamic vegetation model (DVM) we explored the implications of the differing climatic conditions generated by a general circulation model (GCM) in “normal” and “hosing” experiments. Whilst the former approximate interstadial conditions, the latter, designed to mimic Heinrich Events, approximate stadial conditions. The “hosing” experiments gave simulated European vegetation much closer in composition to that inferred from fossil evidence than did the “normal” experiments. Given the short duration of interstadials, and the rate at which forest cover expanded during the late-glacial and early Holocene, our results demonstrate the importance of millennial variability in determining the character of last glacial ecosystems. PMID:23613985

Millennial climatic fluctuations are key to the structure of last glacial ecosystems.

PubMed

Huntley, Brian; Allen, Judy R M; Collingham, Yvonne C; Hickler, Thomas; Lister, Adrian M; Singarayer, Joy; Stuart, Anthony J; Sykes, Martin T; Valdes, Paul J

2013-01-01

Whereas fossil evidence indicates extensive treeless vegetation and diverse grazing megafauna in Europe and northern Asia during the last glacial, experiments combining vegetation models and climate models have to-date simulated widespread persistence of trees. Resolving this conflict is key to understanding both last glacial ecosystems and extinction of most of the mega-herbivores. Using a dynamic vegetation model (DVM) we explored the implications of the differing climatic conditions generated by a general circulation model (GCM) in "normal" and "hosing" experiments. Whilst the former approximate interstadial conditions, the latter, designed to mimic Heinrich Events, approximate stadial conditions. The "hosing" experiments gave simulated European vegetation much closer in composition to that inferred from fossil evidence than did the "normal" experiments. Given the short duration of interstadials, and the rate at which forest cover expanded during the late-glacial and early Holocene, our results demonstrate the importance of millennial variability in determining the character of last glacial ecosystems.

FISHER INFORMATION AND DYNAMIC REGIME CHANGES IN ECOLOGICAL SYTEMS

EPA Science Inventory

Ecosystems often exhibit transitions between dynamic regimes (or steady states), such as the conversion of oligotrophic to eutrophic conditions and associated aquatic ecological communities, due to natural (or increasingly) anthropogenic disturbances. As ecosystems experience per...

Elementary School Children Contribute to Environmental Research as Citizen Scientists.

PubMed

Miczajka, Victoria L; Klein, Alexandra-Maria; Pufal, Gesine

2015-01-01

Research benefits increasingly from valuable contributions by citizen scientists. Mostly, participating adults investigate specific species, ecosystems or phenology to address conservation issues, but ecosystem functions supporting ecosystem health are rarely addressed and other demographic groups rarely involved. As part of a project investigating seed predation and dispersal as ecosystem functions along an urban-rural gradient, we tested whether elementary school children can contribute to the project as citizen scientists. Specifically, we compared data estimating vegetation cover, measuring vegetation height and counting seeds from a seed removal experiment, that were collected by children and scientists in schoolyards. Children counted seeds similarly to scientists but under- or overestimated vegetation cover and measured different heights. We conclude that children can be involved as citizen scientists in research projects according to their skill level. However, more sophisticated tasks require specific training to become familiarized with scientific experiments and the development of needed skills and methods.

A decade of insights into grassland ecosystem responses to global environmental change

USGS Publications Warehouse

Borer, Elizabeth T.; Grace, James B.; Harpole, W. Stanley; MacDougall, Andrew S.; Seabloom, Eric W.

2017-01-01

Earth’s biodiversity and carbon uptake by plants, or primary productivity, are intricately interlinked, underlie many essential ecosystem processes, and depend on the interplay among environmental factors, many of which are being changed by human activities. While ecological theory generalizes across taxa and environments, most empirical tests of factors controlling diversity and productivity have been observational, single-site experiments, or meta-analyses, limiting our understanding of variation among site-level responses and tests of general mechanisms. A synthesis of results from ten years of a globally distributed, coordinated experiment, the Nutrient Network (NutNet), demonstrates that species diversity promotes ecosystem productivity and stability, and that nutrient supply and herbivory control diversity via changes in composition, including invasions of non-native species and extinction of native species. Distributed experimental networks are a powerful tool for tests and integration of multiple theories and for generating multivariate predictions about the effects of global changes on future ecosystems.

A sensor fusion field experiment in forest ecosystem dynamics

NASA Technical Reports Server (NTRS)

Smith, James A.; Ranson, K. Jon; Williams, Darrel L.; Levine, Elissa R.; Goltz, Stewart M.

1990-01-01

The background of the Forest Ecosystem Dynamics field campaign is presented, a progress report on the analysis of the collected data and related modeling activities is provided, and plans for future experiments at different points in the phenological cycle are outlined. The ecological overview of the study site is presented, and attention is focused on forest stands, needles, and atmospheric measurements. Sensor deployment and thermal and microwave observations are discussed, along with two examples of the optical radiation measurements obtained during the experiment in support of radiative transfer modeling. Future activities pertaining to an archival system, synthetic aperture radar, carbon acquisition modeling, and upcoming field experiments are considered.

A large-scale forest fragmentation experiment: the Stability of Altered Forest Ecosystems Project.

PubMed

Ewers, Robert M; Didham, Raphael K; Fahrig, Lenore; Ferraz, Gonçalo; Hector, Andy; Holt, Robert D; Kapos, Valerie; Reynolds, Glen; Sinun, Waidi; Snaddon, Jake L; Turner, Edgar C

2011-11-27

Opportunities to conduct large-scale field experiments are rare, but provide a unique opportunity to reveal the complex processes that operate within natural ecosystems. Here, we review the design of existing, large-scale forest fragmentation experiments. Based on this review, we develop a design for the Stability of Altered Forest Ecosystems (SAFE) Project, a new forest fragmentation experiment to be located in the lowland tropical forests of Borneo (Sabah, Malaysia). The SAFE Project represents an advance on existing experiments in that it: (i) allows discrimination of the effects of landscape-level forest cover from patch-level processes; (ii) is designed to facilitate the unification of a wide range of data types on ecological patterns and processes that operate over a wide range of spatial scales; (iii) has greater replication than existing experiments; (iv) incorporates an experimental manipulation of riparian corridors; and (v) embeds the experimentally fragmented landscape within a wider gradient of land-use intensity than do existing projects. The SAFE Project represents an opportunity for ecologists across disciplines to participate in a large initiative designed to generate a broad understanding of the ecological impacts of tropical forest modification.

A large-scale forest fragmentation experiment: the Stability of Altered Forest Ecosystems Project

PubMed Central

Ewers, Robert M.; Didham, Raphael K.; Fahrig, Lenore; Ferraz, Gonçalo; Hector, Andy; Holt, Robert D.; Kapos, Valerie; Reynolds, Glen; Sinun, Waidi; Snaddon, Jake L.; Turner, Edgar C.

2011-01-01

Opportunities to conduct large-scale field experiments are rare, but provide a unique opportunity to reveal the complex processes that operate within natural ecosystems. Here, we review the design of existing, large-scale forest fragmentation experiments. Based on this review, we develop a design for the Stability of Altered Forest Ecosystems (SAFE) Project, a new forest fragmentation experiment to be located in the lowland tropical forests of Borneo (Sabah, Malaysia). The SAFE Project represents an advance on existing experiments in that it: (i) allows discrimination of the effects of landscape-level forest cover from patch-level processes; (ii) is designed to facilitate the unification of a wide range of data types on ecological patterns and processes that operate over a wide range of spatial scales; (iii) has greater replication than existing experiments; (iv) incorporates an experimental manipulation of riparian corridors; and (v) embeds the experimentally fragmented landscape within a wider gradient of land-use intensity than do existing projects. The SAFE Project represents an opportunity for ecologists across disciplines to participate in a large initiative designed to generate a broad understanding of the ecological impacts of tropical forest modification. PMID:22006969

Peak season carbon exchange shifts from a sink to a source following 50+ years of herbivore exclusion in an Arctic tundra ecosystem

DOE PAGES

Lara, Mark J.; Johnson, David R.; Andresen, Christian; ...

2016-08-27

To date, the majority of our knowledge regarding the impacts of herbivory on arctic ecosystem function has been restricted to short-term (<5 years) exclusion or manipulation experiments. Here, our understanding of long-term responses of sustained herbivory and/or herbivore exclusion on arctic tundra ecosystem function is severely limited.

Using wind-deformed conifers to measure wind patterns in alpine transition at GLEES

Treesearch

Robert C. Musselman; Gene L. Wooldridge; Douglas G. Fox; Bernadette H. Connell

1990-01-01

The Glacier Lakes Ecosystem Experiments Site (GLEES) is a high-elevation ecosystem in the Snowy Range west of Laramie, WY, that is perceived to be highly sensitive to changes in chemical and physical climate. Deposition of atmospheric chemicals to this ecosystem is, in part, governed by the wind pattern. The GLEES has numerous wind-swept areas where the coniferous...

Peak season carbon exchange shifts from a sink to a source following 50+ years of herbivore exclusion in an Arctic tundra ecosystem

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lara, Mark J.; Johnson, David R.; Andresen, Christian

To date, the majority of our knowledge regarding the impacts of herbivory on arctic ecosystem function has been restricted to short-term (<5 years) exclusion or manipulation experiments. Here, our understanding of long-term responses of sustained herbivory and/or herbivore exclusion on arctic tundra ecosystem function is severely limited.

FISHER INFORMATION OF DYNAMIC REGIME TRANSITIONS IN ECOLOGICAL SYSTEMS

EPA Science Inventory

Ecosystems often exhibit transitions between multiple dynamic regimes (or steady states). As ecosystems experience perturbations of varying regularity and intensity, they may either remain within the state space neighborhood of the current regime, or ?flip? into the neighborhood ...

Ecosystem-based management at lower elevations

Treesearch

Stephen F. Arno

2000-01-01

Our experience testing ecosystem-based management (EM) treatments in ponderosa pine (Pinus ponderosa)/fir (Abies spp.) is summarized here. Topics covered include silvicultural treatments, fire application, soils and nutrient considerations, wildlife habitat considerations, associated riparian communities, and treatment of invasive...

Leaf bacterial diversity mediates plant diversity and ecosystem function relationships.

PubMed

Laforest-Lapointe, Isabelle; Paquette, Alain; Messier, Christian; Kembel, Steven W

2017-06-01

Research on biodiversity and ecosystem functioning has demonstrated links between plant diversity and ecosystem functions such as productivity. At other trophic levels, the plant microbiome has been shown to influence host plant fitness and function, and host-associated microbes have been proposed to influence ecosystem function through their role in defining the extended phenotype of host organisms However, the importance of the plant microbiome for ecosystem function has not been quantified in the context of the known importance of plant diversity and traits. Here, using a tree biodiversity-ecosystem functioning experiment, we provide strong support for the hypothesis that leaf bacterial diversity is positively linked to ecosystem productivity, even after accounting for the role of plant diversity. Our results also show that host species identity, functional identity and functional diversity are the main determinants of leaf bacterial community structure and diversity. Our study provides evidence of a positive correlation between plant-associated microbial diversity and terrestrial ecosystem productivity, and a new mechanism by which models of biodiversity-ecosystem functioning relationships can be improved.

Assessing model sensitivity and uncertainty across multiple Free-Air CO2 Enrichment experiments.

NASA Astrophysics Data System (ADS)

Cowdery, E.; Dietze, M.

2015-12-01

As atmospheric levels of carbon dioxide levels continue to increase, it is critical that terrestrial ecosystem models can accurately predict ecological responses to the changing environment. Current predictions of net primary productivity (NPP) in response to elevated atmospheric CO2 concentrations are highly variable and contain a considerable amount of uncertainty. It is necessary that we understand which factors are driving this uncertainty. The Free-Air CO2 Enrichment (FACE) experiments have equipped us with a rich data source that can be used to calibrate and validate these model predictions. To identify and evaluate the assumptions causing inter-model differences we performed model sensitivity and uncertainty analysis across ambient and elevated CO2 treatments using the Data Assimilation Linked Ecosystem Carbon (DALEC) model and the Ecosystem Demography Model (ED2), two process-based models ranging from low to high complexity respectively. These modeled process responses were compared to experimental data from the Kennedy Space Center Open Top Chamber Experiment, the Nevada Desert Free Air CO2 Enrichment Facility, the Rhinelander FACE experiment, the Wyoming Prairie Heating and CO2 Enrichment Experiment, the Duke Forest Face experiment and the Oak Ridge Experiment on CO2 Enrichment. By leveraging data access proxy and data tilling services provided by the BrownDog data curation project alongside analysis modules available in the Predictive Ecosystem Analyzer (PEcAn), we produced automated, repeatable benchmarking workflows that are generalized to incorporate different sites and ecological models. Combining the observed patterns of uncertainty between the two models with results of the recent FACE-model data synthesis project (FACE-MDS) can help identify which processes need further study and additional data constraints. These findings can be used to inform future experimental design and in turn can provide informative starting point for data assimilation.

The role of recurrent disturbances for ecosystem multifunctionality.

PubMed

Villnäs, Anna; Norkko, Joanna; Hietanen, Susanna; Josefson, Alf B; Lukkari, Kaarina; Norkko, Alf

2013-10-01

Ecosystem functioning is threatened by an increasing number of anthropogenic stressors, creating a legacy of disturbance that undermines ecosystem resilience. However, few empirical studies have assessed to what extent an ecosystem can tolerate repeated disturbances and sustain its multiple functions. By inducing increasingly recurring hypoxic disturbances to a sedimentary ecosystem, we show that the majority of individual ecosystem functions experience gradual degradation patterns in response to repetitive pulse disturbances. The degradation in overall ecosystem functioning was, however, evident at an earlier stage than for single ecosystem functions and was induced after a short pulse of hypoxia (i.e., three days), which likely reduced ecosystem resistance to further hypoxic perturbations. The increasing number of repeated pulse disturbances gradually moved the system closer to a press response. In addition to the disturbance regime, the changes in benthic trait composition as well as habitat heterogeneity were important for explaining the variability in overall ecosystem functioning. Our results suggest that disturbance-induced responses across multiple ecosystem functions can serve as a warning signal for losses of the adaptive capacity of an ecosystem, and might at an early stage provide information to managers and policy makers when remediation efforts should be initiated.

Bacterial biodiversity-ecosystem functioning relations are modified by environmental complexity.

PubMed

Langenheder, Silke; Bulling, Mark T; Solan, Martin; Prosser, James I

2010-05-26

With the recognition that environmental change resulting from anthropogenic activities is causing a global decline in biodiversity, much attention has been devoted to understanding how changes in biodiversity may alter levels of ecosystem functioning. Although environmental complexity has long been recognised as a major driving force in evolutionary processes, it has only recently been incorporated into biodiversity-ecosystem functioning investigations. Environmental complexity is expected to strengthen the positive effect of species richness on ecosystem functioning, mainly because it leads to stronger complementarity effects, such as resource partitioning and facilitative interactions among species when the number of available resource increases. Here we implemented an experiment to test the combined effect of species richness and environmental complexity, more specifically, resource richness on ecosystem functioning over time. We show, using all possible combinations of species within a bacterial community consisting of six species, and all possible combinations of three substrates, that diversity-functioning (metabolic activity) relationships change over time from linear to saturated. This was probably caused by a combination of limited complementarity effects and negative interactions among competing species as the experiment progressed. Even though species richness and resource richness both enhanced ecosystem functioning, they did so independently from each other. Instead there were complex interactions between particular species and substrate combinations. Our study shows clearly that both species richness and environmental complexity increase ecosystem functioning. The finding that there was no direct interaction between these two factors, but that instead rather complex interactions between combinations of certain species and resources underlie positive biodiversity ecosystem functioning relationships, suggests that detailed knowledge of how individual species interact with complex natural environments will be required in order to make reliable predictions about how altered levels of biodiversity will most likely affect ecosystem functioning.

Bacterial Biodiversity-Ecosystem Functioning Relations Are Modified by Environmental Complexity

PubMed Central

Langenheder, Silke; Bulling, Mark T.; Solan, Martin; Prosser, James I.

2010-01-01

Background With the recognition that environmental change resulting from anthropogenic activities is causing a global decline in biodiversity, much attention has been devoted to understanding how changes in biodiversity may alter levels of ecosystem functioning. Although environmental complexity has long been recognised as a major driving force in evolutionary processes, it has only recently been incorporated into biodiversity-ecosystem functioning investigations. Environmental complexity is expected to strengthen the positive effect of species richness on ecosystem functioning, mainly because it leads to stronger complementarity effects, such as resource partitioning and facilitative interactions among species when the number of available resource increases. Methodology/Principal Findings Here we implemented an experiment to test the combined effect of species richness and environmental complexity, more specifically, resource richness on ecosystem functioning over time. We show, using all possible combinations of species within a bacterial community consisting of six species, and all possible combinations of three substrates, that diversity-functioning (metabolic activity) relationships change over time from linear to saturated. This was probably caused by a combination of limited complementarity effects and negative interactions among competing species as the experiment progressed. Even though species richness and resource richness both enhanced ecosystem functioning, they did so independently from each other. Instead there were complex interactions between particular species and substrate combinations. Conclusions/Significance Our study shows clearly that both species richness and environmental complexity increase ecosystem functioning. The finding that there was no direct interaction between these two factors, but that instead rather complex interactions between combinations of certain species and resources underlie positive biodiversity ecosystem functioning relationships, suggests that detailed knowledge of how individual species interact with complex natural environments will be required in order to make reliable predictions about how altered levels of biodiversity will most likely affect ecosystem functioning. PMID:20520808

VOC Metabolite Emissions from the Brachypodium/Soil/Microbe Ecosystem

NASA Astrophysics Data System (ADS)

Gu, D.; Shilling, J.; Guenther, A. B.; Lindenmaier, R.

2017-12-01

Volatile Organic Compounds (VOCs) emitted from plants and associated microbiota are important for understanding the plant responses to environmental perturbations. VOC emissions from plants are the largest source of hydrocarbons to the atmosphere, which influence oxidants and aerosols leading to complex feed backs and interactions between atmosphere and biosphere. The integrated Plant-Atmosphere-Soil Systems (iPASS) Initiative is a Pacific Northwest National Laboratory (PNNL) project aimed at deciphering fundamental principles that govern the plant ecosystem, from plant genotype through multiple scales to ecosystem traits and response. We take the opportunity of iPASS initiative, and measured VOC metabolite emissions from the Brachypodium/Soil/Microbe Ecosystem. In the experiments, we have been working on (1) identifying VOC metabolites emitted by Brachypodium plants using dynamic vegetation enclosure measurements, (2) understanding the relative contribution of plants, microbes, and soil to VOC emissions, (3) investigating changes that occur in these emissions under different induced stress, and (4) relating VOC emissions from the plant/soil/microbe ecosystem to plant genotype. Taking advantage of experiment results, we also can develop a noninvasive technique for quantifying plant stress by using VOC observations, use VOC observations to improve screening tool for identifying stress resistant phenotypes, and apply the measurements into earth system modeling for better understanding of the impacts of stress on ecosystems.

Nonlinear, interacting responses to climate limit grassland production under global change.

PubMed

Zhu, Kai; Chiariello, Nona R; Tobeck, Todd; Fukami, Tadashi; Field, Christopher B

2016-09-20

Global changes in climate, atmospheric composition, and pollutants are altering ecosystems and the goods and services they provide. Among approaches for predicting ecosystem responses, long-term observations and manipulative experiments can be powerful approaches for resolving single-factor and interactive effects of global changes on key metrics such as net primary production (NPP). Here we combine both approaches, developing multidimensional response surfaces for NPP based on the longest-running, best-replicated, most-multifactor global-change experiment at the ecosystem scale-a 17-y study of California grassland exposed to full-factorial warming, added precipitation, elevated CO2, and nitrogen deposition. Single-factor and interactive effects were not time-dependent, enabling us to analyze each year as a separate realization of the experiment and extract NPP as a continuous function of global-change factors. We found a ridge-shaped response surface in which NPP is humped (unimodal) in response to temperature and precipitation when CO2 and nitrogen are ambient, with peak NPP rising under elevated CO2 or nitrogen but also shifting to lower temperatures. Our results suggest that future climate change will push this ecosystem away from conditions that maximize NPP, but with large year-to-year variability.

Plant ecology. Anthropogenic environmental changes affect ecosystem stability via biodiversity.

PubMed

Hautier, Yann; Tilman, David; Isbell, Forest; Seabloom, Eric W; Borer, Elizabeth T; Reich, Peter B

2015-04-17

Human-driven environmental changes may simultaneously affect the biodiversity, productivity, and stability of Earth's ecosystems, but there is no consensus on the causal relationships linking these variables. Data from 12 multiyear experiments that manipulate important anthropogenic drivers, including plant diversity, nitrogen, carbon dioxide, fire, herbivory, and water, show that each driver influences ecosystem productivity. However, the stability of ecosystem productivity is only changed by those drivers that alter biodiversity, with a given decrease in plant species numbers leading to a quantitatively similar decrease in ecosystem stability regardless of which driver caused the biodiversity loss. These results suggest that changes in biodiversity caused by drivers of environmental change may be a major factor determining how global environmental changes affect ecosystem stability. Copyright © 2015, American Association for the Advancement of Science.

Metabolic and physiochemical responses to a whole-lake experimental increase in dissolved organic carbon in a north-temperate lake

USGS Publications Warehouse

Zwart, Jacob A.; Craig, Nicola; Kelly, Patrick T.; Sebestyen, Stephen D.; Solomon, Christopher T.; Weidel, Brian C.; Jones, Stuart E.

2016-01-01

Over the last several decades, many lakes globally have increased in dissolved organic carbon (DOC), calling into question how lake functions may respond to increasing DOC. Unfortunately, our basis for making predictions is limited to spatial surveys, modeling, and laboratory experiments, which may not accurately capture important whole-ecosystem processes. In this article, we present data on metabolic and physiochemical responses of a multiyear experimental whole-lake increase in DOC concentration. Unexpectedly, we observed an increase in pelagic gross primary production, likely due to a small increase in phosphorus as well as a surprising lack of change in epilimnetic light climate. We also speculate on the importance of lake size modifying the relationship between light climate and elevated DOC. A larger increase in ecosystem respiration resulted in an increased heterotrophy for the treatment basin. The magnitude of the increase in heterotrophy was extremely close to the excess DOC load to the treatment basin, indicating that changes in heterotrophy may be predictable if allochthonous carbon loads are well-constrained. Elevated DOC concentration also reduced thermocline and mixed layer depth and reduced whole-lake temperature. Results from this experiment were quantitatively different, and sometimes even in the opposite direction, from expectations based on cross-system surveys and bottle experiments, emphasizing the importance of whole-ecosystem experiments in understanding ecosystem response to environmental change.

Funding Mechanisms for Ecosystem Services Projects

NASA Astrophysics Data System (ADS)

Russell, V.

2014-12-01

Ecosystem services projects ideally should be funded through commoditized markets. Where those markets do not exist financing directly from interested private sector parties can be a direct link between business interested in fulfilling sustainability goals and project implementers. Challenges exist, however in 1) linking those interests; 2) carefully quantifying the services produced, their true costs to implement and meeting protocol standards; 3) measuring the success of projects, especially over lengthy periods of time; and 4) balancing issues related to multiple spatial scales for projects and funding to make a difference. Examples from National Forest Foundation's experience implementing carbon and water projects with multiple private sector funders and the USDA Forest Service will highlight experiences and lessons learned in funding and implementing ecosystem service projects.

NEW SAMPLING THEORY FOR MEASURING ECOSYSTEM STRUCTURE

EPA Science Inventory

This research considered the application of systems analysis to the study of laboratory ecosystems. The work concerned the development of a methodology which was shown to be useful in the design of laboratory experiments, the processing and interpretation of the results of these ...

ANPP-precipitation relationships in multi-year drought experiments in natural ecosystems

USDA-ARS?s Scientific Manuscript database

Background/Question/Methods Predicting the effects of a reduction in precipitations on ecosystem productivity confronts an uncertainty: the relationship between aboveground net primary productivity (ANPP) and precipitation differs if the focus is spatial, driven by the climatic mean annual precipi...

USING FISHER INFORMATION TO DETECT GRADUAL AND RAPID ECOSYSTEM REGIME SHIFTS

EPA Science Inventory

As ecosystems experience perturbations of varying regularity and intensity, they may either remain within the state space neighborhood of the current regime, or "flip" into the neighborhood of a regime with different characteristics. Although the possibility of such regime shifts...

The relative importance of pollinator abundance and species richness for the temporal variance of pollination services.

PubMed

Genung, Mark A; Fox, Jeremy; Williams, Neal M; Kremen, Claire; Ascher, John; Gibbs, Jason; Winfree, Rachael

2017-07-01

The relationship between biodiversity and the stability of ecosystem function is a fundamental question in community ecology, and hundreds of experiments have shown a positive relationship between species richness and the stability of ecosystem function. However, these experiments have rarely accounted for common ecological patterns, most notably skewed species abundance distributions and non-random extinction risks, making it difficult to know whether experimental results can be scaled up to larger, less manipulated systems. In contrast with the prolific body of experimental research, few studies have examined how species richness affects the stability of ecosystem services at more realistic, landscape scales. The paucity of these studies is due in part to a lack of analytical methods that are suitable for the correlative structure of ecological data. A recently developed method, based on the Price equation from evolutionary biology, helps resolve this knowledge gap by partitioning the effect of biodiversity into three components: richness, composition, and abundance. Here, we build on previous work and present the first derivation of the Price equation suitable for analyzing temporal variance of ecosystem services. We applied our new derivation to understand the temporal variance of crop pollination services in two study systems (watermelon and blueberry) in the mid-Atlantic United States. In both systems, but especially in the watermelon system, the stronger driver of temporal variance of ecosystem services was fluctuations in the abundance of common bee species, which were present at nearly all sites regardless of species richness. In contrast, temporal variance of ecosystem services was less affected by differences in species richness, because lost and gained species were rare. Thus, the findings from our more realistic landscapes differ qualitatively from the findings of biodiversity-stability experiments. © 2017 by the Ecological Society of America.

Measuring conditions and trends in ecosystem services at multiple scales: the Southern African Millennium Ecosystem Assessment (SAfMA) experience

PubMed Central

van Jaarsveld, A.S; Biggs, R; Scholes, R.J; Bohensky, E; Reyers, B; Lynam, T; Musvoto, C; Fabricius, C

2005-01-01

The Southern African Millennium Ecosystem Assessment (SAfMA) evaluated the relationships between ecosystem services and human well-being at multiple scales, ranging from local through to sub-continental. Trends in ecosystem services (fresh water, food, fuel-wood, cultural and biodiversity) over the period 1990–2000 were mixed across scales. Freshwater resources appear strained across the continent with large numbers of people not securing adequate supplies, especially of good quality water. This translates to high infant mortality patterns across the region. In some areas, the use of water resources for irrigated agriculture and urban–industrial expansion is taking place at considerable cost to the quality and quantity of freshwater available to ecosystems and for domestic use. Staple cereal production across the region has increased but was outstripped by population growth while protein malnutrition is on the rise. The much-anticipated wood-fuel crisis on the subcontinent has not materialized but some areas are experiencing shortages while numerous others remain vulnerable. Cultural benefits of biodiversity are considerable, though hard to quantify or track over time. Biodiversity resources remain at reasonable levels, but are declining faster than reflected in species extinction rates and appear highly sensitive to land-use decisions. The SAfMA sub-global assessment provided an opportunity to experiment with innovative ways to assess ecosystem services including the use of supply–demand surfaces, service sources and sink areas, priority areas for service provision, service ‘hotspots’ and trade-off assessments. PMID:15814355

Measuring conditions and trends in ecosystem services at multiple scales: the Southern African Millennium Ecosystem Assessment (SAfMA) experience.

PubMed

van Jaarsveld, A S; Biggs, R; Scholes, R J; Bohensky, E; Reyers, B; Lynam, T; Musvoto, C; Fabricius, C

2005-02-28

The Southern African Millennium Ecosystem Assessment (SAfMA) evaluated the relationships between ecosystem services and human well-being at multiple scales, ranging from local through to sub-continental. Trends in ecosystem services (fresh water, food, fuel-wood, cultural and biodiversity) over the period 1990-2000 were mixed across scales. Freshwater resources appear strained across the continent with large numbers of people not securing adequate supplies, especially of good quality water. This translates to high infant mortality patterns across the region. In some areas, the use of water resources for irrigated agriculture and urban-industrial expansion is taking place at considerable cost to the quality and quantity of freshwater available to ecosystems and for domestic use. Staple cereal production across the region has increased but was outstripped by population growth while protein malnutrition is on the rise. The much-anticipated wood-fuel crisis on the subcontinent has not materialized but some areas are experiencing shortages while numerous others remain vulnerable. Cultural benefits of biodiversity are considerable, though hard to quantify or track over time. Biodiversity resources remain at reasonable levels, but are declining faster than reflected in species extinction rates and appear highly sensitive to land-use decisions. The SAfMA sub-global assessment provided an opportunity to experiment with innovative ways to assess ecosystem services including the use of supply-demand surfaces, service sources and sink areas, priority areas for service provision, service 'hotspots' and trade-off assessments.

Soil Carbon Inputs and Ecosystem Respiration: a Field Priming Experiment in Arctic Coastal Tundra

NASA Astrophysics Data System (ADS)

Vaughn, L. S.; Zhu, B.; Bimueller, C.; Curtis, J. B.; Chafe, O.; Bill, M.; Abramoff, R. Z.; Torn, M. S.

2016-12-01

In Arctic ecosystems, climate change is expected to influence soil carbon stocks through changes in both plant carbon inputs and organic matter decomposition. This study addresses the potential for a priming effect, an interaction between these changes in which root-derived carbon inputs alter SOM decomposition rates via microbial biomass increases, co-metabolism of substrates, induced nitrogen limitation, or other possible mechanisms. The priming effect has been observed in numerous laboratory and greenhouse experiments, and is increasingly included in ecosystem models. Few studies, however, have evaluated the priming effect with in situ field manipulations. In a two-year field experiment in Barrow, Alaska, we tested for a priming effect under natural environmental variability. In September 2014 and August 2015, we added 6.1g of 13C-labeled glucose to 25cm diameter mesocosms, 15cm below the soil surface in the mineral soil layer. Over the following month, we quantified effects on the rate and temperature sensitivity of native (non-glucose) ecosystem respiration and GPP. Following the 2014 treatment, soil samples were collected at 1 and 3 weeks for microbial biomass carbon and 13C/12C analysis, and ion exchange membranes were buried for one week to assess nitrate and ammonium availability. In contrast with many laboratory incubation studies using soils from a broad range of ecosystems, we observed no significant priming effect. In spite of a clear signal of 13C-glucose decomposition in respired CO2 and microbial biomass, we detected no treatment effect on background ecosystem respiration or total microbial biomass carbon. Our findings suggest that glucose taken up by microbes was not used for production of additional SOM-decomposing enzymes, possibly due to stoichiometric limitations on enzyme production. To best inform models representing complex and dynamic ecosystems, this study calls for further research relating theory, laboratory findings, and field experimentation.

Model estimates of net primary productivity, evaportranspiration, and water use efficiency in the terrestrial ecosystems of the southern United States

Treesearch

Hanqin Tian; Guangsheng Chen; Mingliang Liu; Chi Zhang; Ge Sun; Chaoqun Lu; Xiaofeng Xu; Wei Ren; Shufen Pan; Arthur Chappelka

2010-01-01

The effects of global change on ecosystem productivity and water resources in the southern United States (SUS), a traditionally ‘water-rich’ region and the ‘timber basket’ of the country, are not well quantified. We carried out several simulation experiments to quantify ecosystem net primary productivity (NPP), evapotranspiration (ET)...

Amazon rainforest responses to elevated CO2: Deriving model-based hypotheses for the AmazonFACE experiment

NASA Astrophysics Data System (ADS)

Rammig, A.; Fleischer, K.; Lapola, D.; Holm, J.; Hoosbeek, M.

2017-12-01

Increasing atmospheric CO2 concentration is assumed to have a stimulating effect ("CO2 fertilization effect") on forest growth and resilience. Empirical evidence, however, for the existence and strength of such a tropical CO2 fertilization effect is scarce and thus a major impediment for constraining the uncertainties in Earth System Model projections. The implications of the tropical CO2 effect are far-reaching, as it strongly influences the global carbon and water cycle, and hence future global climate. In the scope of the Amazon Free Air CO2 Enrichment (FACE) experiment, we addressed these uncertainties by assessing the CO2 fertilization effect at ecosystem scale. AmazonFACE is the first FACE experiment in an old-growth, highly diverse tropical rainforest. Here, we present a priori model-based hypotheses for the experiment derived from a set of 12 ecosystem models. Model simulations identified key uncertainties in our understanding of limiting processes and derived model-based hypotheses of expected ecosystem responses to elevated CO2 that can directly be tested during the experiment. Ambient model simulations compared satisfactorily with in-situ measurements of ecosystem carbon fluxes, as well as carbon, nitrogen, and phosphorus stocks. Models consistently predicted an increase in photosynthesis with elevated CO2, which declined over time due to developing limitations. The conversion of enhanced photosynthesis into biomass, and hence ecosystem carbon sequestration, varied strongly among the models due to different assumptions on nutrient limitation. Models with flexible allocation schemes consistently predicted an increased investment in belowground structures to alleviate nutrient limitation, in turn accelerating turnover rates of soil organic matter. The models diverged on the prediction for carbon accumulation after 10 years of elevated CO2, mainly due to contrasting assumptions in their phosphorus cycle representation. These differences define the expected response ratio to elevated CO2 at the AmazonFACE site and identify priorities for experimental work and model development.

Arctic Messages: Arctic Research in the Vocabulary of Poets and Artists

NASA Astrophysics Data System (ADS)

Samsel, F.

2017-12-01

Arctic Messages is a series of prints created by a multidisciplinary team designed to build understanding and encourage dialogue about the changing Arctic ecosystems and the impacts on global weather patterns. Our team comprised of Arctic researchers, a poet, a visual artist, photographers and visualization experts set out to blend the vocabularies of our disciplines in order to provide entry into the content for diverse audiences. Arctic Messages is one facet of our broader efforts experimenting with mediums of communication able to provide entry to those of us outside scientific of fields. We believe that the scientific understanding of change presented through the languages art will speak to our humanity as well as our intellect. The prints combine poetry, painting, visualization, and photographs, drawn from the Arctic field studies of the Next Generation Ecosystem Experiments research team at Los Alamos National Laboratory. The artistic team interviewed the scientists, read their papers and poured over their field blogs. The content and concepts are designed to portray the wonder of nature, the complexity of the science and the dedication of the researchers. Smith brings to life the intertwined connection between the research efforts, the ecosystems and the scientist's experience. Breathtaking photography of the research site is accompanied by Samsel's drawings and paintings of the ecosystem relationships and geological formations. Together they provide entry to the variety and wonder of life on the Arctic tundra and that resting quietly in the permafrost below. Our team has experimented with many means of presentation from complex interactive systems to quiet individual works. Here we are presenting a series of prints, each one based on a single thread of the research or the scientist's experience but containing intertwined relationships similar to the ecosystems they represent. Earlier interactive systems, while engaging, were not tuned to those seeking quieter contemplation. The long linear work spreads across the wall enable viewers to explore the content of interest at the pace and through the vocabulary that speaks to them.

Northern Forest DroughtNet: A New Framework to Understand Impacts of Precipitation Change on the Northern Forest Ecosystem

NASA Astrophysics Data System (ADS)

Asbjornsen, H.; Rustad, L.; Templer, P. H.; Jennings, K.; Phillips, R.; Smith, M.

2014-12-01

Recent trends and projections for future change for the U.S. northern forests suggest that the region's climate is becoming warmer, wetter, and, ironically, drier, with more precipitation occurring as large events, separated by longer periods with no precipitation. However, to date, precipitation manipulation experiments conducted in forest ecosystems represent only ~5% of all such experiments worldwide, and our understanding of how the mesic-adapted northern forest will respond to greater frequency and intensity of drought in the future is especially poor. Several important challenges have hampered previous research efforts to conduct forest drought experiments and draw robust conclusions, including difficulties in reducing water uptake by deep and lateral tree roots, logistical and financial constraints to establishing and maintaining large-scale field experiments, and the lack of standardized approaches for determining the appropriate precipitation manipulation treatment (e.g., amount and timing of throughfall displacement), designing and constructing the throughfall displacement infrastructure, identifying key response variables, and collecting and analyzing the field data. The overarching goal of this project is to establish a regional research coordination network - Northern Forest DroughtNet - to investigate the impacts of changes in the amount and distribution of precipitation on the hydrology, biogeochemistry, and carbon (C) cycling dynamics of northern temperate forests. Specific objectives include the development of a standard prototype for conducting precipitation manipulation studies in forest ecosystems (in collaboration with the international DroughtNet-RCN) and the implementation of this prototype drought experiment at the Hubbard Brook Experimental Forest. Here, we present the advances made thus far towards achieving the objectives of Northern Forest DroughtNet, plans for future work, and an invitation to the larger scientific community interested in precipitation manipulation experiments in forest ecosystems to participate in the network.

Realistic diversity loss and variation in soil depth independently affect community-level plant nitrogen use.

PubMed

Selmants, Paul C; Zavaleta, Erika S; Wolf, Amelia A

2014-01-01

Numerous experiments have demonstrated that diverse plant communities use nitrogen (N) more completely and efficiently, with implications for how species conservation efforts might influence N cycling and retention in terrestrial ecosystems. However, most such experiments have randomly manipulated species richness and minimized environmental heterogeneity, two design aspects that may reduce applicability to real ecosystems. Here we present results from an experiment directly comparing how realistic and randomized plant species losses affect plant N use across a gradient of soil depth in a native-dominated serpentine grassland in California. We found that the strength of the species richness effect on plant N use did not increase with soil depth in either the realistic or randomized species loss scenarios, indicating that the increased vertical heterogeneity conferred by deeper soils did not lead to greater complementarity among species in this ecosystem. Realistic species losses significantly reduced plant N uptake and altered N-use efficiency, while randomized species losses had no effect on plant N use. Increasing soil depth positively affected plant N uptake in both loss order scenarios but had a weaker effect on plant N use than did realistic species losses. Our results illustrate that realistic species losses can have functional consequences that differ distinctly from randomized losses, and that species diversity effects can be independent of and outweigh those of environmental heterogeneity on ecosystem functioning. Our findings also support the value of conservation efforts aimed at maintaining biodiversity to help buffer ecosystems against increasing anthropogenic N loading.

Ecosystem Consequences of Contrasting Flow Regimes in an Urban Effects Stream Mesocosm Study

EPA Science Inventory

A stream mesocosm experiment was conducted to study the ecosystem-wide effects of two replicated flow hydrograph treatments programmed in an attempt to compare a simulated predevelopment condition to the theoretical changes that new development brings, while accounting for engine...

USING FISHER INFORMATION TO ASSESS THE RISK OF DYNAMIC REGIME CHANGES IN ECOLOGICAL SYSTEMS

EPA Science Inventory

The sustainable nature of particular dynamic regimes of ecosystems is an increasingly integral aspect of many ecological, economic, and social decisions. As ecosystems experience perturbations of varying regularity and intensity, they may either remain within the state space neig...

A global examination of the response of ecosystem water-use efficiency to drought based on MODIS data.

PubMed

Huang, Ling; He, Bin; Han, Le; Liu, Junjie; Wang, Haiyan; Chen, Ziyue

2017-12-01

Ecosystem water-use efficiency (WUE) plays an important role in carbon and water cycles. Currently, the response of WUE to drought disturbance remains controversial. Based on the global ecosystem gross primary productivity (GPP) product and the evapotranspiration product (ET), both of which were retrieved from the moderate resolution imaging spectroradiometer (MODIS), as well as the drought index, this study comprehensively examined the relationship between ecosystem WUE (WUE=GPP/ET) and drought at the global scale. The response of WUE to drought showed large differences in various regions and biomes. WUE for arid ecosystems typically showed a negative response to drought, whereas WUE for humid ecosystems showed both positive and negative response to drought. Legacy effects of drought on ecosystem WUE were observed. Furthermore, ecosystems showed a sensitive response to abrupt changes in hydrological climatic conditions. The transition from wet to dry years should increase ecosystem WUE, and the opposite change in WUE should occur when an ecosystem experiences a transition from dry to wet years. This indicates the resilience of ecosystems to drought disturbance. Knowledge from this study should provide an in-depth understanding of ecosystem strategies for coping with drought. Copyright © 2017 Elsevier B.V. All rights reserved.

The up-scaling of ecosystem functions in a heterogeneous world

NASA Astrophysics Data System (ADS)

Lohrer, Andrew M.; Thrush, Simon F.; Hewitt, Judi E.; Kraan, Casper

2015-05-01

Earth is in the midst of a biodiversity crisis that is impacting the functioning of ecosystems and the delivery of valued goods and services. However, the implications of large scale species losses are often inferred from small scale ecosystem functioning experiments with little knowledge of how the dominant drivers of functioning shift across scales. Here, by integrating observational and manipulative experimental field data, we reveal scale-dependent influences on primary productivity in shallow marine habitats, thus demonstrating the scalability of complex ecological relationships contributing to coastal marine ecosystem functioning. Positive effects of key consumers (burrowing urchins, Echinocardium cordatum) on seafloor net primary productivity (NPP) elucidated by short-term, single-site experiments persisted across multiple sites and years. Additional experimentation illustrated how these effects amplified over time, resulting in greater primary producer biomass sediment chlorophyll a content (Chla) in the longer term, depending on climatic context and habitat factors affecting the strengths of mutually reinforcing feedbacks. The remarkable coherence of results from small and large scales is evidence of real-world ecosystem function scalability and ecological self-organisation. This discovery provides greater insights into the range of responses to broad-scale anthropogenic stressors in naturally heterogeneous environmental settings.

The up-scaling of ecosystem functions in a heterogeneous world

PubMed Central

Lohrer, Andrew M.; Thrush, Simon F.; Hewitt, Judi E.; Kraan, Casper

2015-01-01

Earth is in the midst of a biodiversity crisis that is impacting the functioning of ecosystems and the delivery of valued goods and services. However, the implications of large scale species losses are often inferred from small scale ecosystem functioning experiments with little knowledge of how the dominant drivers of functioning shift across scales. Here, by integrating observational and manipulative experimental field data, we reveal scale-dependent influences on primary productivity in shallow marine habitats, thus demonstrating the scalability of complex ecological relationships contributing to coastal marine ecosystem functioning. Positive effects of key consumers (burrowing urchins, Echinocardium cordatum) on seafloor net primary productivity (NPP) elucidated by short-term, single-site experiments persisted across multiple sites and years. Additional experimentation illustrated how these effects amplified over time, resulting in greater primary producer biomass sediment chlorophyll a content (Chla) in the longer term, depending on climatic context and habitat factors affecting the strengths of mutually reinforcing feedbacks. The remarkable coherence of results from small and large scales is evidence of real-world ecosystem function scalability and ecological self-organisation. This discovery provides greater insights into the range of responses to broad-scale anthropogenic stressors in naturally heterogeneous environmental settings. PMID:25993477

Nitrogen and Sulfur Deposition Effects on Forest Biogeochemical Processes.

NASA Astrophysics Data System (ADS)

Goodale, C. L.

2014-12-01

Chronic atmospheric deposition of nitrogen and sulfur have widely ranging biogeochemical consequences in terrestrial ecosystems. Both N and S deposition can affect plant growth, decomposition, and nitrous oxide production, with sometimes synergistic and sometimes contradictory responses; yet their separate effects are rarely isolated and their interactive biogeochemical impacts are often overlooked. For example, S deposition and consequent acidification and mortality may negate stimulation of plant growth induced by N deposition; decomposition can be slowed by both N and S deposition, though through different mechanisms; and N2O production may be stimulated directly by N and indirectly by S amendments. Recent advances in conceptual models and whole-ecosystem experiments provide novel means for disentangling the impacts of N and S in terrestrial ecosystems. Results from a new whole-ecosystem N x S- addition experiment will be presented in detail, examining differential response of tree and soil carbon storage to N and S additions. These results combine with observations from a broad array of long-term N addition studies, atmospheric deposition gradients, stable isotope tracer studies, and model analyses to inform the magnitude, controls, and stability of ecosystem C storage in response to N and S addition.

Guiding the Next Generation of Forest FACE Experiments with Lessons from the Past

NASA Astrophysics Data System (ADS)

Norby, Richard

2016-04-01

The free air CO2 enrichment (FACE) experiments that were initiated in forest ecosystems 20 years ago represented a large commitment of time and energy of many students, early career, and senior scientists, and they were a substantial investment of funding from government science agencies. The experiments produced hundreds of primary research papers and dozens of synthesis and review papers, so it is highly appropriate to ask: What did we learn from this enterprise about how trees and forests will respond to an ever increasing concentration of CO2 in the atmosphere? The diversity of sites and species preclude any single, simple answer. Nevertheless, the FACE experiments were successful in building upon earlier, smaller scale elevated CO2 experiments to provide the data needed to evaluate hypotheses derived from past results, and they provided novel insights into the ecological mechanisms controlling the cycling and storage of carbon in terrestrial ecosystems. Important lessons include: (1) Net primary productivity is increased by elevated CO2, but the response can diminish over time. (2) Carbon accumulation is driven by the distribution of carbon among plant and soil components with differing turnover rates and by interactions between the carbon and nitrogen cycles. (3) Plant community structure may change, but elevated CO2 has only minor effects on microbial community structure. However, despite these insights, the size and longevity of forests preclude experimental evaluation, even in decade-long experiments, of the critical global-scale issues associated with forest responses to rising atmospheric CO2 concentration and the feedbacks provided to the climate system. Instead, we must rely on models that simulate the exchange of carbon, water, and energy in the terrestrial biosphere. An important objective of FACE experiments has always been to provide data and evaluation tools for ecosystem models and thereby contribute to our ability to project how ecosystems will respond to future CO2 concentrations. The FACE model-data synthesis (FACE-MDS) project challenged 11 terrestrial ecosystem models with data from the Oak Ridge National Laboratory FACE experiment in Tennessee, USA, and Duke FACE in North Carolina, USA. This exercise was valuable in identifying critical model assumptions and evaluating whether the assumptions were supported by the experimental data, and it provided a framework to evaluate forest processes that occur over much longer time frames than the duration of the experiments. The next generation of forest FACE experiments will greatly expand the breadth of our knowledge base on responses to elevated CO2 by investigating responses of mature forest ecosystems in boreal to tropical biomes over a wide range of climatic and edaphic conditions. Our experience with the FACE-MDS has shown the value in initiating the model-data interaction as an integral part of experimental design. The FACE-MDS framework has led to a set of model-guided, cross-site science questions for new FACE experiments, including responses of mature forests; interactions with temperature, water stress, and phosphorus limitation; and the influence of biodiversity. This sets an exciting research agenda for the next decade.

Integrated ocean management as a strategy to meet rapid climate change: the Norwegian case.

PubMed

Hoel, Alf Håkon; Olsen, Erik

2012-02-01

The prospects of rapid climate change and the potential existence of tipping points in marine ecosystems where nonlinear change may result from them being overstepped, raises the question of strategies for coping with ecosystem change. There is broad agreement that the combined forces of climate change, pollution and increasing economic activities necessitates more comprehensive approaches to oceans management, centering on the concept of ecosystem-based oceans management. This article addresses the Norwegian experience in introducing integrated, ecosystem-based oceans management, emphasizing how climate change, seen as a major long-term driver of change in ecosystems, is addressed in management plans. Understanding the direct effects of climate variability and change on ecosystems and indirect effects on human activities is essential for adaptive planning to be useful in the long-term management of the marine environment.

The challenge of integrating ecosystem health throughout a veterinary curriculum.

PubMed

Stephen, Craig

2009-01-01

This paper focuses on the question, "How can concepts of ecosystem health be made widely applicable to the diverse interests of veterinary students?" To date, most effort has focused on promoting the training of veterinarians to take an active role in the field of ecosystem health. Less attention has been placed on how ecosystem health can be made useful and valuable to the full spectrum of students, from those intending to pursue careers in ecosystem health to those seeking employment in private clinical practice. The lack of standard curricula and expectations for ecosystem health courses makes it impossible to assess how educational experiences can be combined to deliver and assess the best course. In this paper, teaching goals and teaching techniques are suggested for institutions that are seeking to weave ecosystem health throughout their curricula. Rather than dogmatically defining ecosystem health, this paper outlines potential goals and attitudes for undergraduate veterinary education that can be extracted from the conceptual foundations of ecosystem health, health promotion, and population health. The participatory nature of ecosystem health argues in favor of teaching methods that are experiential, exploitative of stories, and inclusive of a diverse group of teachers and role models.

Use of Hyperspectral Aircraft Remote Sensing to Support Ecosystems Services Research in New England Lakes and Ponds

EPA Science Inventory

Northeastern lakes and ponds provide important ecosystem services to New England residents and visitors. These include the provisioning of abundant, clean water for consumption, agriculture, and industry as well as cultural services (recreation, aesthetics, and wilderness experie...

Impacts of air pollution and climate change on forest ecosystems - Multiple stressors and ecosystem services

EPA Science Inventory

The nature of scientific investigation involving hypothesis testing dictates the need to conduct controlled experiments, limiting the number of independent variables in order to identify cause and effect relationships. Single or two-factor studies are useful to identify potentia...

Ecosystem experiment reveals benefits of natural and simulated beaver dams to a threatened population of steelhead (Oncorhynchus mykiss)

PubMed Central

Bouwes, Nicolaas; Weber, Nicholas; Jordan, Chris E.; Saunders, W. Carl; Tattam, Ian A.; Volk, Carol; Wheaton, Joseph M.; Pollock, Michael M.

2016-01-01

Beaver have been referred to as ecosystem engineers because of the large impacts their dam building activities have on the landscape; however, the benefits they may provide to fluvial fish species has been debated. We conducted a watershed-scale experiment to test how increasing beaver dam and colony persistence in a highly degraded incised stream affects the freshwater production of steelhead (Oncorhynchus mykiss). Following the installation of beaver dam analogs (BDAs), we observed significant increases in the density, survival, and production of juvenile steelhead without impacting upstream and downstream migrations. The steelhead response occurred as the quantity and complexity of their habitat increased. This study is the first large-scale experiment to quantify the benefits of beavers and BDAs to a fish population and its habitat. Beaver mediated restoration may be a viable and efficient strategy to recover ecosystem function of previously incised streams and to increase the production of imperiled fish populations. PMID:27373190

Impact of Altered Precipitation Patterns on Plant Productivity and Soil Respiration in a Northern Great Plains Grassland

NASA Astrophysics Data System (ADS)

Haase, L.; Flanagan, L. B.

2017-12-01

Precipitation patterns are expected to shift towards larger but fewer rain events, with longer intermittent dry periods, associated with climate change. The larger rain events may compensate for and help to mitigate climate change effects on key ecosystem functions such as plant productivity and soil respiration in semi-arid grasslands. We experimentally manipulated the amount and frequency of simulated precipitation added to trenched, treatment plots that were covered by rain shelters, and measured the response in plant productivity and soil respiration in a native, grassland ecosystem near Lethbridge, Alberta. We compared the observed responses to the predictions of a conceptual ecosystem response model developed by Knapp et al. 2008 (BioScience 58: 811-821). Two experiments were conducted during 14 weeks of the growing season from May-August. The first experiment (normal amount) applied total growing season precipitation of 180 mm (climate normal), and the second experiment (reduced amount) applied total precipitation of 90 mm. In both experiments, precipitation was applied at two frequencies, 1 rain event every week (normal frequency) and 1 rain event every two weeks (reduced frequency). In the normal amount experiment, the average rain event was 12.8 mm for the normal frequency treatment and 25.8 mm for the reduced frequency treatment. In the reduced amount experiment, the average rain event was 6.4 mm for the normal frequency treatment and 12.8 mm for the reduced frequency treatment. We hypothesized that larger but fewer rain events would result in increased plant productivity and soil respiration for both experiments. Plant greenness values calculated from digital photographs were used as a proxy for plant productivity, and showed significantly higher values for the normal vs. reduced amount experiment. Soil respiration rate also showed significantly higher values for the normal vs. reduced amount experiment. No significant treatment effect could be detected between the normal vs. reduced frequency treatments in both experiments for either the plant greenness or soil respiration measurements. The results of this study have implications for understanding the mechanisms underlying ecosystem responses to anticipated precipitation change in the Great Plains.

Spatially cascading effect of perturbations in experimental meta-ecosystems.

PubMed

Harvey, Eric; Gounand, Isabelle; Ganesanandamoorthy, Pravin; Altermatt, Florian

2016-09-14

Ecosystems are linked to neighbouring ecosystems not only by dispersal, but also by the movement of subsidy. Such subsidy couplings between ecosystems have important landscape-scale implications because perturbations in one ecosystem may affect community structure and functioning in neighbouring ecosystems via increased/decreased subsidies. Here, we combine a general theoretical approach based on harvesting theory and a two-patch protist meta-ecosystem experiment to test the effect of regional perturbations on local community dynamics. We first characterized the relationship between the perturbation regime and local population demography on detritus production using a mathematical model. We then experimentally simulated a perturbation gradient affecting connected ecosystems simultaneously, thus altering cross-ecosystem subsidy exchanges. We demonstrate that the perturbation regime can interact with local population dynamics to trigger unexpected temporal variations in subsidy pulses from one ecosystem to another. High perturbation intensity initially led to the highest level of subsidy flows; however, the level of perturbation interacted with population dynamics to generate a crash in subsidy exchange over time. Both theoretical and experimental results show that a perturbation regime interacting with local community dynamics can induce a collapse in population levels for recipient ecosystems. These results call for integrative management of human-altered landscapes that takes into account regional dynamics of both species and resource flows. © 2016 The Author(s).

CLIMATIC EFFECTS ON TUNDRA CARBON STORAGE INFERRED FROM EXPERIMENTAL DATA AND A MODEL

EPA Science Inventory

We used a process-based model of ecosystem carbon (C) and nitrogen (N)dynamics, MBL-GEM (Marine Biological Laboratory General Ecosystem Model), to integrated and analyze the results of several experiments that examined the response of arctic tussock tundra to manipulations of CO2...

ECO-Report - One ranger's experience in summer 2000

Treesearch

Janie Canton-Thompson; Greg Jones; Jane Kapler Smith; Peter Rice; Mick Harrington; Elaine Kennedy Sutherland; Kevin McKelvey; Yvette Ortega; Ward McCaughey; Robert Pfister; Greg Jones; Larry Swanson; Vita Wright

2001-01-01

ECO-Report is an annual Rocky Mountain Research Station (RMRS) publication which contains a set of articles showcasing the Bitterroot Ecosystem Management Research Project (BEMRP) research projects and activities. The articles are concise, user-friendly, and designed to inform a broad range of audiences interested in ecosystem management. Articles featured in...

Grassland Smoke Emission Measurement Supporting Multi-Modeling Framework Simulation of Rangeland Burning Practices for the Kansas Flint Hills Fire Experiment

EPA Science Inventory

Historically, frequent wildfires were essential for the maintenance of native prairie fire adapted ecosystems. Today prescribed fires are used to control invasive woody species and potentially improve forage production in these same prairie ecosystems for the beef-cattle industry...

IMPLICATIONS OF INTER-HABITAT VARIATION FOR MONITORING GREAT RIVER ECOSYSTEMS: EMAP-UMR EXPERIENCE

EPA Science Inventory

Great River ecosystems (GREs) are complex mosaics of habitats that vary at multiple scales. GRE monitoring designs can capture some but not all of this variation. Each discrete habitat, however defined, must either be sampled as a separate strata or "resource population", combine...

A Method for Analyzing Volunteered Geographic Information to Visualize Community Valuation of Ecosystem Services

EPA Science Inventory

Volunteered geographic information (VGI) can be used to identify public valuation of ecosystem services in a defined geographic area using photos as a representation of lived experiences. This method can help researchers better survey and report on the values and preferences of s...

Resolving drivers of variability in estuarine metabolism from in situ and experimental measurements at paired sites in a warm temperate Pensacola Bay, Florida

EPA Science Inventory

We investigated the integrated ecosystem properties (gross production, respiration, and net ecosystem metabolism) in the Pensacola Bay estuary, using a combination of instrument deployments and plankton metabolism experiments. High-frequency water quality data were collected from...

An Ecosystem Approach to Invasive Species Management: An Aquatic Ecosystem Case Study

ERIC Educational Resources Information Center

Villamagna, A. M.; Karpanty, S. M.

2009-01-01

College students in natural resources continue to encounter instructor-centered teaching, despite strong evidence that suggests active-learning experiences benefit students more than passive learning activities. Case studies provide an active-learning alternative to lectures by teaching students new content and challenging them to engage in…

Near real time observational data collection for SPRUCE experiment- PakBus protocol for slow satellite connections

NASA Astrophysics Data System (ADS)

Krassovski, Misha; Hanson, Paul; Riggs, Jeff

2017-04-01

Climate change studies are one of the most important aspects of modern science and related experiments are getting bigger and more complex. One such experiment is the Spruce and Peatland Responses Under Climatic and Environmental Change experiment (SPRUCE, http://mnspruce.ornl.gov) conducted in in northern Minnesota, 40 km north of Grand Rapids, in the USDA Forest Service Marcell Experimental Forest (MEF). The SPRUCE experimental mission is to assess ecosystem-level biological responses of vulnerable, high carbon terrestrial ecosystems to a range of climate warming manipulations and an elevated CO2 atmosphere. This manipulation experiment generates a lot of observational data and requires a reliable onsite data collection system, dependable methods to transfer data to a robust scientific facility, and real-time monitoring capabilities. This publication shares our experience of establishing near real time data collection and monitoring system via a satellite link using PakBus protocol.

Near real time/low latency data collection for climate warming manipulations and an elevated CO2 SPRUCE experiment

NASA Astrophysics Data System (ADS)

Krassovski, M.; Hanson, P. J.; Riggs, J. S.; Nettles, W. R., IV

2017-12-01

Climate change studies are one of the most important aspects of modern science and related experiments are getting bigger and more complex. One such experiment is the Spruce and Peatland Responses Under Climatic and Environmental Change experiment (SPRUCE, http://mnspruce.ornl.gov) conducted in in northern Minnesota, 40 km north of Grand Rapids, in the USDA Forest Service Marcell Experimental Forest (MEF). The SPRUCE experimental mission is to assess ecosystem-level biological responses of vulnerable, high carbon terrestrial ecosystems to a range of climate warming manipulations and an elevated CO2 atmosphere. This manipulation experiment generates a lot of observational data and requires a reliable onsite data collection system, dependable methods to transfer data to a robust scientific facility, and real-time monitoring capabilities. This presentation shares our experience of establishing near real time/low latency data collection and monitoring system using satellite communication.

Abundance of common species, not species richness, drives delivery of a real-world ecosystem service.

PubMed

Winfree, Rachael; Fox, Jeremy W; Williams, Neal M; Reilly, James R; Cariveau, Daniel P

2015-07-01

Biodiversity-ecosystem functioning experiments have established that species richness and composition are both important determinants of ecosystem function in an experimental context. Determining whether this result holds for real-world ecosystem services has remained elusive, however, largely due to the lack of analytical methods appropriate for large-scale, associational data. Here, we use a novel analytical approach, the Price equation, to partition the contribution to ecosystem services made by species richness, composition and abundance in four large-scale data sets on crop pollination by native bees. We found that abundance fluctuations of dominant species drove ecosystem service delivery, whereas richness changes were relatively unimportant because they primarily involved rare species that contributed little to function. Thus, the mechanism behind our results was the skewed species-abundance distribution. Our finding that a few common species, not species richness, drive ecosystem service delivery could have broad generality given the ubiquity of skewed species-abundance distributions in nature. © 2015 John Wiley & Sons Ltd/CNRS.

Development of simplified ecosystem models for applications in Earth system studies: The Century experience

NASA Technical Reports Server (NTRS)

Parton, William J.; Ojima, Dennis S.; Schimel, David S.; Kittel, Timothy G. F.

1992-01-01

During the past decade, a growing need to conduct regional assessments of long-term trends of ecosystem behavior and the technology to meet this need have converged. The Century model is the product of research efforts initially intended to develop a general model of plant-soil ecosystem dynamics for the North American central grasslands. This model is now being used to simulate plant production, nutrient cycling, and soil organic matter dynamics for grassland, crop, forest, and shrub ecosystems in various regions of the world, including temperate and tropical ecosystems. This paper will focus on the philosophical approach used to develop the structure of Century. The steps included were model simplification, parameterization, and testing. In addition, the importance of acquiring regional data bases for model testing and the present regional application of Century in the Great Plains, which focus on regional ecosystem dynamics and the effect of altering environmental conditions, are discussed.

Trophic cascades triggered by overfishing reveal possible mechanisms of ecosystem regime shifts.

PubMed

Daskalov, Georgi M; Grishin, Alexander N; Rodionov, Sergei; Mihneva, Vesselina

2007-06-19

Large-scale transitions between alternative states in ecosystems are known as regime shifts. Once described as healthy and dominated by various marine predators, the Black Sea ecosystem by the late 20th century had experienced anthropogenic impacts such as heavy fishing, cultural eutrophication, and invasions by alien species. We studied changes related to these "natural experiments" to reveal the mechanisms of regime shifts. Two major shifts were detected, the first related to a depletion of marine predators and the second to an outburst of the alien comb jelly Mnemiopsis leidyi; both shifts were triggered by intense fishing resulting in system-wide trophic cascades. The complex nature of ecosystem responses to human activities calls for more elaborate approaches than currently provided by traditional environmental and fisheries management. This implies challenging existing practices and implementing explanatory models of ecosystem interactions that can better reconcile conservation and ecosystem management ideals.

Reconstructing disturbances and their biogeochemical consequences over multiple timescales

USGS Publications Warehouse

McLauchlan, Kendra K.; Higuera, Philip E.; Gavin, Daniel G.; Perakis, Steven S.; Mack, Michelle C.; Alexander, Heather; Battles, John; Biondi, Franco; Buma, Brian; Colombaroli, Daniele; Enders, Sara K.; Engstrom, Daniel R.; Hu, Feng Sheng; Marlon, Jennifer R.; Marshall, John; McGlone, Matt; Morris, Jesse L.; Nave, Lucas E.; Shuman, Bryan; Smithwick, Erica A.H.; Urrego, Dunia H.; Wardle, David A.; Williams, Christopher J.; Williams, Joseph J.

2014-01-01

Ongoing changes in disturbance regimes are predicted to cause acute changes in ecosystem structure and function in the coming decades, but many aspects of these predictions are uncertain. A key challenge is to improve the predictability of postdisturbance biogeochemical trajectories at the ecosystem level. Ecosystem ecologists and paleoecologists have generated complementary data sets about disturbance (type, severity, frequency) and ecosystem response (net primary productivity, nutrient cycling) spanning decadal to millennial timescales. Here, we take the first steps toward a full integration of these data sets by reviewing how disturbances are reconstructed using dendrochronological and sedimentary archives and by summarizing the conceptual frameworks for carbon, nitrogen, and hydrologic responses to disturbances. Key research priorities include further development of paleoecological techniques that reconstruct both disturbances and terrestrial ecosystem dynamics. In addition, mechanistic detail from disturbance experiments, long-term observations, and chronosequences can help increase the understanding of ecosystem resilience.

Impact des herbicides sur les écosystèmes forestiers et aquatiques et la faune sauvage: l'expérience américaine. (Impact of herbicides on the forest ecosystem, aquatic ecosystems, and wildlife - The US Experience)

Treesearch

Jerry Lee Michael

2003-01-01

The impact of forestry herbicides on ecosystems, terrestrial and aquatic, is a subject which has received much attention. That attention increased with the publication of Rachel Carson's book Silent Spring in 1962. At that time, several chlorinated hydrocarbons were in wide spread use in the US and around the world, the most well known of which...

A comprehensive data acquisition and management system for an ecosystem-scale peatland warming and elevated CO2 experiment

NASA Astrophysics Data System (ADS)

Krassovski, M. B.; Riggs, J. S.; Hook, L. A.; Nettles, W. R.; Hanson, P. J.; Boden, T. A.

2015-07-01

Ecosystem-scale manipulation experiments represent large science investments that require well-designed data acquisition and management systems to provide reliable, accurate information to project participants and third party users. The SPRUCE Project (Spruce and Peatland Responses Under Climatic and Environmental Change, http://mnspruce.ornl.gov) is such an experiment funded by the Department of Energy's (DOE), Office of Science, Terrestrial Ecosystem Science (TES) Program. The SPRUCE experimental mission is to assess ecosystem-level biological responses of vulnerable, high carbon terrestrial ecosystems to a range of climate warming manipulations and an elevated CO2 atmosphere. SPRUCE provides a platform for testing mechanisms controlling the vulnerability of organisms, biogeochemical processes, and ecosystems to climatic change (e.g., thresholds for organism decline or mortality, limitations to regeneration, biogeochemical limitations to productivity, the cycling and release of CO2 and CH4 to the atmosphere). The SPRUCE experiment will generate a wide range of continuous and discrete measurements. To successfully manage SPRUCE data collection, achieve SPRUCE science objectives, and support broader climate change research, the research staff has designed a flexible data system using proven network technologies and software components. The primary SPRUCE data system components are: 1. Data acquisition and control system - set of hardware and software to retrieve biological and engineering data from sensors, collect sensor status information, and distribute feedback to control components. 2. Data collection system - set of hardware and software to deliver data to a central depository for storage and further processing. 3. Data management plan - set of plans, policies, and practices to control consistency, protect data integrity, and deliver data. This publication presents our approach to meeting the challenges of designing and constructing an efficient data system for managing high volume sources of in-situ observations in a remote, harsh environmental location. The approach covers data flow starting from the sensors and ending at the archival/distribution points, discusses types of hardware and software used, examines design considerations that were used to choose them, and describes the data management practices chosen to control and enhance the value of the data.

A comprehensive data acquisition and management system for an ecosystem-scale peatland warming and elevated CO2 experiment

NASA Astrophysics Data System (ADS)

Krassovski, M. B.; Riggs, J. S.; Hook, L. A.; Nettles, W. R.; Hanson, P. J.; Boden, T. A.

2015-11-01

Ecosystem-scale manipulation experiments represent large science investments that require well-designed data acquisition and management systems to provide reliable, accurate information to project participants and third party users. The SPRUCE project (Spruce and Peatland Responses Under Climatic and Environmental Change, http://mnspruce.ornl.gov) is such an experiment funded by the Department of Energy's (DOE), Office of Science, Terrestrial Ecosystem Science (TES) Program. The SPRUCE experimental mission is to assess ecosystem-level biological responses of vulnerable, high carbon terrestrial ecosystems to a range of climate warming manipulations and an elevated CO2 atmosphere. SPRUCE provides a platform for testing mechanisms controlling the vulnerability of organisms, biogeochemical processes, and ecosystems to climatic change (e.g., thresholds for organism decline or mortality, limitations to regeneration, biogeochemical limitations to productivity, and the cycling and release of CO2 and CH4 to the atmosphere). The SPRUCE experiment will generate a wide range of continuous and discrete measurements. To successfully manage SPRUCE data collection, achieve SPRUCE science objectives, and support broader climate change research, the research staff has designed a flexible data system using proven network technologies and software components. The primary SPRUCE data system components are the following: 1. data acquisition and control system - set of hardware and software to retrieve biological and engineering data from sensors, collect sensor status information, and distribute feedback to control components; 2. data collection system - set of hardware and software to deliver data to a central depository for storage and further processing; 3. data management plan - set of plans, policies, and practices to control consistency, protect data integrity, and deliver data. This publication presents our approach to meeting the challenges of designing and constructing an efficient data system for managing high volume sources of in situ observations in a remote, harsh environmental location. The approach covers data flow starting from the sensors and ending at the archival/distribution points, discusses types of hardware and software used, examines design considerations that were used to choose them, and describes the data management practices chosen to control and enhance the value of the data.

Bryophytes and Organic layers Control Uptake of Airborne Nitrogen in Low-N Environments.

PubMed

Bähring, Alexandra; Fichtner, Andreas; Friedrich, Uta; von Oheimb, Goddert; Härdtle, Werner

2017-01-01

The effects of atmospheric nitrogen (N) deposition on ecosystem functioning largely depend on the retention of N in different ecosystem compartments, but accumulation and partitioning processes have rarely been quantified in long-term field experiments. In the present study we analysed for the first time decadal-scale flows and allocation patterns of N in a heathland ecosystem that has been subject to airborne N inputs over decades. Using a long-term 15 N tracer experiment, we quantified N retention and flows to and between ecosystem compartments (above-ground/below-ground vascular biomass, moss layer, soil horizons, leachate). After 9 years, about 60% of the added 15 N-tracer remained in the N cycle of the ecosystem. The moss layer proved to be a crucial link between incoming N and its allocation to different ecosystem compartments (in terms of a short-term capture, but long-term release function). However, about 50% of the 15 N captured and released by the moss layer was not compensated for by a corresponding increase in recovery rates in any other compartment, probably due to denitrification losses from the moss layer in the case of water saturation after rain events. The O-horizon proved to be the most important long-term sink for added 15 N, as reflected by an increase in recovery rates from 18 to 40% within 8 years. Less than 2.1% of 15 N were recovered in the podzol-B-horizon, suggesting that only negligible amounts of N were withdrawn from the N cycle of the ecosystem. Moreover, 15 N recovery was low in the dwarf shrub above-ground biomass (<3.9% after 9 years) and in the leachate (about 0.03% within 1 year), indicating still conservative N cycles of the ecosystem, even after decades of N inputs beyond critical load thresholds. The continuous accumulation of reactive forms of airborne N suggests that critical load-estimates need to account for cumulative effects of N additions into ecosystems.

Bryophytes and Organic layers Control Uptake of Airborne Nitrogen in Low-N Environments

PubMed Central

Bähring, Alexandra; Fichtner, Andreas; Friedrich, Uta; von Oheimb, Goddert; Härdtle, Werner

2017-01-01

The effects of atmospheric nitrogen (N) deposition on ecosystem functioning largely depend on the retention of N in different ecosystem compartments, but accumulation and partitioning processes have rarely been quantified in long-term field experiments. In the present study we analysed for the first time decadal-scale flows and allocation patterns of N in a heathland ecosystem that has been subject to airborne N inputs over decades. Using a long-term 15N tracer experiment, we quantified N retention and flows to and between ecosystem compartments (above-ground/below-ground vascular biomass, moss layer, soil horizons, leachate). After 9 years, about 60% of the added 15N-tracer remained in the N cycle of the ecosystem. The moss layer proved to be a crucial link between incoming N and its allocation to different ecosystem compartments (in terms of a short-term capture, but long-term release function). However, about 50% of the 15N captured and released by the moss layer was not compensated for by a corresponding increase in recovery rates in any other compartment, probably due to denitrification losses from the moss layer in the case of water saturation after rain events. The O-horizon proved to be the most important long-term sink for added 15N, as reflected by an increase in recovery rates from 18 to 40% within 8 years. Less than 2.1% of 15N were recovered in the podzol-B-horizon, suggesting that only negligible amounts of N were withdrawn from the N cycle of the ecosystem. Moreover, 15N recovery was low in the dwarf shrub above-ground biomass (<3.9% after 9 years) and in the leachate (about 0.03% within 1 year), indicating still conservative N cycles of the ecosystem, even after decades of N inputs beyond critical load thresholds. The continuous accumulation of reactive forms of airborne N suggests that critical load-estimates need to account for cumulative effects of N additions into ecosystems. PMID:29375589

Biodiversity-ecosystem functioning relationships in long-term time series and palaeoecological records: deep sea as a test bed.

PubMed

Yasuhara, Moriaki; Doi, Hideyuki; Wei, Chih-Lin; Danovaro, Roberto; Myhre, Sarah E

2016-05-19

The link between biodiversity and ecosystem functioning (BEF) over long temporal scales is poorly understood. Here, we investigate biological monitoring and palaeoecological records on decadal, centennial and millennial time scales from a BEF framework by using deep sea, soft-sediment environments as a test bed. Results generally show positive BEF relationships, in agreement with BEF studies based on present-day spatial analyses and short-term manipulative experiments. However, the deep-sea BEF relationship is much noisier across longer time scales compared with modern observational studies. We also demonstrate with palaeoecological time-series data that a larger species pool does not enhance ecosystem stability through time, whereas higher abundance as an indicator of higher ecosystem functioning may enhance ecosystem stability. These results suggest that BEF relationships are potentially time scale-dependent. Environmental impacts on biodiversity and ecosystem functioning may be much stronger than biodiversity impacts on ecosystem functioning at long, decadal-millennial, time scales. Longer time scale perspectives, including palaeoecological and ecosystem monitoring data, are critical for predicting future BEF relationships on a rapidly changing planet. © 2016 The Author(s).

Environmental proteomics reveals taxonomic and functional changes in an enriched aquatic ecosystem.

PubMed

Northrop, Amanda C; Brooks, Rachel; Ellison, Aaron M; Gotelli, Nicholas J; Ballif, Bryan A

2017-10-01

Aquatic ecosystem enrichment can lead to distinct and irreversible changes to undesirable states. Understanding changes in active microbial community function and composition following organic-matter loading in enriched ecosystems can help identify biomarkers of such state changes. In a field experiment, we enriched replicate aquatic ecosystems in the pitchers of the northern pitcher plant, Sarracenia purpurea . Shotgun metaproteomics using a custom metagenomic database identified proteins, molecular pathways, and contributing microbial taxa that differentiated control ecosystems from those that were enriched. The number of microbial taxa contributing to protein expression was comparable between treatments; however, taxonomic evenness was higher in controls. Functionally active bacterial composition differed significantly among treatments and was more divergent in control pitchers than enriched pitchers. Aerobic and facultative anaerobic bacteria contributed most to identified proteins in control and enriched ecosystems, respectively. The molecular pathways and contributing taxa in enriched pitcher ecosystems were similar to those found in larger enriched aquatic ecosystems and are consistent with microbial processes occurring at the base of detrital food webs. Detectable differences between protein profiles of enriched and control ecosystems suggest that a time series of environmental proteomics data may identify protein biomarkers of impending state changes to enriched states.

Greenhouse gas exchange in tropical mountain ecosystems in Tanzania

NASA Astrophysics Data System (ADS)

Gerschlauer, Friederike; Kikoti, Imani; Kiese, Ralf

2014-05-01

Tropical mountain ecosystems with their mostly immense biodiversity are important regions for natural resources but also for agricultural production. Their supportive ecosystem processes are particularly vulnerable to the combined impacts of global warming and the conversion of natural to human-modified landscapes. Data of impacts of climate and land use change on soil-atmosphere interactions due to GHG (CO2, CH4, and N2O) exchange from these ecosystems are still scarce, in particular for Africa. Tropical forest soils are underestimated as sinks for atmospheric CH4 with regard to worldwide GHG budgets (Werner et al. 2007, J GEOPHYS RES Vol. 112). Even though these soils are an important source for the atmospheric N2O budget, N2O emissions from tropical forest ecosystems are still poorly characterized (Castaldi et al. 2013, Biogeosciences 10). To obtain an insight of GHG balances of selected ecosystems soil-atmosphere exchange of N2O, CH4 and CO2 was investigated along the southern slope of Mt. Kilimanjaro, Tanzania. We will present results for tropical forests in three different altitudes (lower montane, Ocotea, and Podocarpus forest), home garden (extensive agro-forestry), and coffee plantation (intensive agro-forestry). Therefore we used a combined approach consisting of a laboratory parameterization experiment (3 temperature and 2 moisture levels) and in situ static chamber measurements for GHG exchange. Field measurements were conducted during different hygric seasons throughout two years. Seasonal variation of temperature and especially of soil moisture across the different ecosystems resulted in distinct differences in GHG exchange. In addition environmental parameters like soil bulk density and substrate availability varying in space strongly influenced the GHG fluxes within sites. The results from parameterization experiments and in situ measurements show that natural forest ecosystems and extensive land use had higher uptakes of CH4. For the investigated forest ecosystems we found considerable differences in soil sink strength for CH4. N2O emissions were highest in natural forest ecosystems even though N input in the intensively managed system was considerably higher. Highest N2O efflux rates were identified in the region of highest mean annual precipitation. CO2 emissions reduced from managed to natural ecosystems. In general an increase in temperature as well as in soil moisture caused higher GHG fluxes throughout all investigated natural and managed ecosystems. With increasing altitude of the investigated forests GHG emissions reduced overall.

Spatial interactions among ecosystem services in an urbanizing agricultural watershed

PubMed Central

Qiu, Jiangxiao; Turner, Monica G.

2013-01-01

Understanding spatial distributions, synergies, and tradeoffs of multiple ecosystem services (benefits people derive from ecosystems) remains challenging. We analyzed the supply of 10 ecosystem services for 2006 across a large urbanizing agricultural watershed in the Upper Midwest of the United States, and asked the following: (i) Where are areas of high and low supply of individual ecosystem services, and are these areas spatially concordant across services? (ii) Where on the landscape are the strongest tradeoffs and synergies among ecosystem services located? (iii) For ecosystem service pairs that experience tradeoffs, what distinguishes locations that are “win–win” exceptions from other locations? Spatial patterns of high supply for multiple ecosystem services often were not coincident; locations where six or more services were produced at high levels (upper 20th percentile) occupied only 3.3% of the landscape. Most relationships among ecosystem services were synergies, but tradeoffs occurred between crop production and water quality. Ecosystem services related to water quality and quantity separated into three different groups, indicating that management to sustain freshwater services along with other ecosystem services will not be simple. Despite overall tradeoffs between crop production and water quality, some locations were positive for both, suggesting that tradeoffs are not inevitable everywhere and might be ameliorated in some locations. Overall, we found that different areas of the landscape supplied different suites of ecosystem services, and their lack of spatial concordance suggests the importance of managing over large areas to sustain multiple ecosystem services. PMID:23818612

Spatial interactions among ecosystem services in an urbanizing agricultural watershed.

PubMed

Qiu, Jiangxiao; Turner, Monica G

2013-07-16

Understanding spatial distributions, synergies, and tradeoffs of multiple ecosystem services (benefits people derive from ecosystems) remains challenging. We analyzed the supply of 10 ecosystem services for 2006 across a large urbanizing agricultural watershed in the Upper Midwest of the United States, and asked the following: (i) Where are areas of high and low supply of individual ecosystem services, and are these areas spatially concordant across services? (ii) Where on the landscape are the strongest tradeoffs and synergies among ecosystem services located? (iii) For ecosystem service pairs that experience tradeoffs, what distinguishes locations that are "win-win" exceptions from other locations? Spatial patterns of high supply for multiple ecosystem services often were not coincident; locations where six or more services were produced at high levels (upper 20th percentile) occupied only 3.3% of the landscape. Most relationships among ecosystem services were synergies, but tradeoffs occurred between crop production and water quality. Ecosystem services related to water quality and quantity separated into three different groups, indicating that management to sustain freshwater services along with other ecosystem services will not be simple. Despite overall tradeoffs between crop production and water quality, some locations were positive for both, suggesting that tradeoffs are not inevitable everywhere and might be ameliorated in some locations. Overall, we found that different areas of the landscape supplied different suites of ecosystem services, and their lack of spatial concordance suggests the importance of managing over large areas to sustain multiple ecosystem services.

Measuring conflicts in the management of anthropized ecosystems: Evidence from a choice experiment in a human-created Mediterranean wetland.

PubMed

Perni, Ángel; Martínez-Paz, José Miguel

2017-12-01

Economic valuation of ecosystem services provides valuable information for the management of anthropized environments, where individual preferences can be heterogeneous and even opposed. Here, we discuss how these ecosystem services were approached in the literature and we address the main issues in relation to their economic valuation. We consider that avoiding misspecifications in economic valuation surveys requires considering the linkages between anthropized ecosystems and human intervention. To illustrate, we analyse the case study of a human-created Mediterranean wetland (El Hondo, SE Spain) using a Choice Experiment. Our findings suggest that management strategies in El Hondo should be oriented to improve the water ecological status, to enhance biodiversity and to develop ecotourism, whereas hunting should be strictly limited and controlled. Our measures of conflict (trade-off between ecosystem services and willingness to pay values) can help to find the optimal allocation of public and private goods and services and for the implementation of compensation schemes in the area. According to public preferences, a conservationist management strategy would generate 331,100 €/year in terms of environmental benefits, whereas a tourism-based management strategy would benefit society with 805,200 €/year. Copyright © 2017 Elsevier Ltd. All rights reserved.

Biodiversity, photosynthetic mode, and ecosystem services differ between native and novel ecosystems.

PubMed

Martin, Leanne M; Polley, H Wayne; Daneshgar, Pedram P; Harris, Mary A; Wilsey, Brian J

2014-06-01

Human activities have caused non-native plant species with novel ecological interactions to persist on landscapes, and it remains controversial whether these species alter multiple aspects of communities and ecosystems. We tested whether native and exotic grasslands differ in species diversity, ecosystem services, and an important aspect of functional diversity (C3:C4 proportions) by sampling 42 sites along a latitudinal gradient and conducting a controlled experiment. Exotic-dominated grasslands had drastically lower plant diversity and slightly higher tissue N concentrations and forage quality compared to native-dominated sites. Exotic sites were strongly dominated by C4 species at southern and C3 species at northern latitudes with a sharp transition at 36-38°, whereas native sites contained C3:C4 mixtures. Large differences in C3:C4 proportions and temporal niche partitioning were found between native and exotic mixtures in the experiment, implying that differences in C3:C4 proportions along the latitudinal gradient are caused partially by species themselves. Our results indicate that the replacement of native- by exotic-dominated grasslands has created a management tradeoff (high diversity versus high levels of certain ecosystem services) and that models of global change impacts and C3/C4 distribution should consider effects of exotic species.

Asymmetric warming significantly affects net primary production, but not ecosystem carbon balances of forest and grassland ecosystems in northern China

NASA Astrophysics Data System (ADS)

Su, Hongxin; Feng, Jinchao; Axmacher, Jan C.; Sang, Weiguo

2015-03-01

We combine the process-based ecosystem model (Biome-BGC) with climate change-scenarios based on both RegCM3 model outputs and historic observed trends to quantify differential effects of symmetric and asymmetric warming on ecosystem net primary productivity (NPP), heterotrophic respiration (Rh) and net ecosystem productivity (NEP) of six ecosystem types representing different climatic zones of northern China. Analysis of covariance shows that NPP is significant greater at most ecosystems under the various environmental change scenarios once temperature asymmetries are taken into consideration. However, these differences do not lead to significant differences in NEP, which indicates that asymmetry in climate change does not result in significant alterations of the overall carbon balance in the dominating forest or grassland ecosystems. Overall, NPP, Rh and NEP are regulated by highly interrelated effects of increases in temperature and atmospheric CO2 concentrations and precipitation changes, while the magnitude of these effects strongly varies across the six sites. Further studies underpinned by suitable experiments are nonetheless required to further improve the performance of ecosystem models and confirm the validity of these model predictions. This is crucial for a sound understanding of the mechanisms controlling the variability in asymmetric warming effects on ecosystem structure and functioning.

Asymmetric warming significantly affects net primary production, but not ecosystem carbon balances of forest and grassland ecosystems in northern China.

PubMed

Su, Hongxin; Feng, Jinchao; Axmacher, Jan C; Sang, Weiguo

2015-03-13

We combine the process-based ecosystem model (Biome-BGC) with climate change-scenarios based on both RegCM3 model outputs and historic observed trends to quantify differential effects of symmetric and asymmetric warming on ecosystem net primary productivity (NPP), heterotrophic respiration (Rh) and net ecosystem productivity (NEP) of six ecosystem types representing different climatic zones of northern China. Analysis of covariance shows that NPP is significant greater at most ecosystems under the various environmental change scenarios once temperature asymmetries are taken into consideration. However, these differences do not lead to significant differences in NEP, which indicates that asymmetry in climate change does not result in significant alterations of the overall carbon balance in the dominating forest or grassland ecosystems. Overall, NPP, Rh and NEP are regulated by highly interrelated effects of increases in temperature and atmospheric CO2 concentrations and precipitation changes, while the magnitude of these effects strongly varies across the six sites. Further studies underpinned by suitable experiments are nonetheless required to further improve the performance of ecosystem models and confirm the validity of these model predictions. This is crucial for a sound understanding of the mechanisms controlling the variability in asymmetric warming effects on ecosystem structure and functioning.

Asymmetric warming significantly affects net primary production, but not ecosystem carbon balances of forest and grassland ecosystems in northern China

PubMed Central

Su, Hongxin; Feng, Jinchao; Axmacher, Jan C.; Sang, Weiguo

2015-01-01

We combine the process-based ecosystem model (Biome-BGC) with climate change-scenarios based on both RegCM3 model outputs and historic observed trends to quantify differential effects of symmetric and asymmetric warming on ecosystem net primary productivity (NPP), heterotrophic respiration (Rh) and net ecosystem productivity (NEP) of six ecosystem types representing different climatic zones of northern China. Analysis of covariance shows that NPP is significant greater at most ecosystems under the various environmental change scenarios once temperature asymmetries are taken into consideration. However, these differences do not lead to significant differences in NEP, which indicates that asymmetry in climate change does not result in significant alterations of the overall carbon balance in the dominating forest or grassland ecosystems. Overall, NPP, Rh and NEP are regulated by highly interrelated effects of increases in temperature and atmospheric CO2 concentrations and precipitation changes, while the magnitude of these effects strongly varies across the six sites. Further studies underpinned by suitable experiments are nonetheless required to further improve the performance of ecosystem models and confirm the validity of these model predictions. This is crucial for a sound understanding of the mechanisms controlling the variability in asymmetric warming effects on ecosystem structure and functioning. PMID:25766381

The influence of balanced and imbalanced resource supply on biodiversity-functioning relationship across ecosystems.

PubMed

Lewandowska, Aleksandra M; Biermann, Antje; Borer, Elizabeth T; Cebrián-Piqueras, Miguel A; Declerck, Steven A J; De Meester, Luc; Van Donk, Ellen; Gamfeldt, Lars; Gruner, Daniel S; Hagenah, Nicole; Harpole, W Stanley; Kirkman, Kevin P; Klausmeier, Christopher A; Kleyer, Michael; Knops, Johannes M H; Lemmens, Pieter; Lind, Eric M; Litchman, Elena; Mantilla-Contreras, Jasmin; Martens, Koen; Meier, Sandra; Minden, Vanessa; Moore, Joslin L; Venterink, Harry Olde; Seabloom, Eric W; Sommer, Ulrich; Striebel, Maren; Trenkamp, Anastasia; Trinogga, Juliane; Urabe, Jotaro; Vyverman, Wim; Van de Waal, Dedmer B; Widdicombe, Claire E; Hillebrand, Helmut

2016-05-19

Numerous studies show that increasing species richness leads to higher ecosystem productivity. This effect is often attributed to more efficient portioning of multiple resources in communities with higher numbers of competing species, indicating the role of resource supply and stoichiometry for biodiversity-ecosystem functioning relationships. Here, we merged theory on ecological stoichiometry with a framework of biodiversity-ecosystem functioning to understand how resource use transfers into primary production. We applied a structural equation model to define patterns of diversity-productivity relationships with respect to available resources. Meta-analysis was used to summarize the findings across ecosystem types ranging from aquatic ecosystems to grasslands and forests. As hypothesized, resource supply increased realized productivity and richness, but we found significant differences between ecosystems and study types. Increased richness was associated with increased productivity, although this effect was not seen in experiments. More even communities had lower productivity, indicating that biomass production is often maintained by a few dominant species, and reduced dominance generally reduced ecosystem productivity. This synthesis, which integrates observational and experimental studies in a variety of ecosystems and geographical regions, exposes common patterns and differences in biodiversity-functioning relationships, and increases the mechanistic understanding of changes in ecosystems productivity. © 2016 The Author(s).

SOLAS Science and the Environmental Impacts of Geoengineering

NASA Astrophysics Data System (ADS)

Boyd, P.; Law, C. S.

2016-02-01

SOLAS (Surface Ocean Lower Atmosphere Study) has played a major role in establishing the elemental and ecosystem responses in the in situ mesoscale iron addition experiments. The outcomes of these experiments have included a Summary for Policymakers and an amendment on ocean fertilisation in the London Convention on marine dumping, which have informed both the debate and international regulation on this potential geoengineering approach. As part of Future Earth the next ten years of SOLAS Science will develop understanding and fundamental science in 5 major themes, including Greenhouse Gases and the Ocean, Interconnections between Aerosol, Clouds and Ecosystems, and Ocean Biogeochemical Controls on Atmospheric Chemistry. This poster will review the SOLAS science areas that provide fundamental knowledge on processes and ecosystem impacts, which is required for the robust assessment of potential Solar Radiation Management and Carbon Dioxide Removal techniques.

Children's Conceptions of Sampling in Local Ecosystems Investigations

ERIC Educational Resources Information Center

Lehrer, Richard; Schauble, Leona

2017-01-01

This study describes how students' intuitions about sampling are informed by extended experiences in investigating local ecosystems. Elementary students in a rural/suburban district in the upper midwest spent a year conducting first-hand comparative field studies of nearby ponds, prairies, and forests. At the close of the term, we conducted…

SIPEX--Exploring the Antarctic Sea Ice Zone

ERIC Educational Resources Information Center

Zicus, Sandra; Dobson, Jane; Worby, Anthony

2008-01-01

Sea ice in the polar regions plays a key role in both regulating global climate and maintaining marine ecosystems. The international Sea Ice Physics and Ecosystem eXperiment (SIPEX) explored the sea ice zone around Antarctica in September and October 2007, investigating relationships between the physical sea ice environment and the structure of…

Sierra Nevada Ecosystem Project

Treesearch

C. I. Millar

1996-01-01

Sierra Nevada Ecosystems. The Sierra Nevada evokes images particular to each individual's experience of the range. These images take on the quality of immutability, and we expect to find the range basically unchanged from one year to the next. The Sierra Nevada, however, including its rocky foundations and the plants and animals that inhabit it, changes...

Ecosystem Management Research in the Ouachita Mountains: Pretreatment Conditions and Preliminary Findings

Treesearch

James B. Baker

1994-01-01

In August 1990, USDA Forest Service researchers from the Southern Forest Experiment Station and resource managers from the Ouachita and Ozark National Forests embarked on a major ecosystem management (then called New Perspectives) research program aimed at formulating, implementing, and evaluating partial cutting methods in shortleaf pine-hardwood stands as...

ELEVATED CO2 AND TEMPERATURE ALTER THE ECOSYSTEM C EXCHANGE IN A YOUNG DOUGLAS FIR MESOCOSM EXPERIMENT

EPA Science Inventory

We investigated the effects of elevated CO2 (EC) [ambient CO2 (AC) + 190 ppm] and elevated temperature (ET) [ambient temperature (AT) + 3.6 °C] on net ecosystem exchange (NEE) of seedling Douglas fir (Pseudotsuga menziesii) mesocosms. As the study utilized seedlings in reconstruc...

Tightly-coupled plant-soil nitrogen cycling: Implications for multiple ecosystem services on organic farms across an intensively managed agricultural landscape

USDA-ARS?s Scientific Manuscript database

Variability among farms across an agricultural landscape may reveal diverse biophysical contexts and experiences that show innovations and insights to improve nitrogen (N) cycling and yields, and thus the potential for multiple ecosystem services. In order to assess potential tradeoffs between yield...

Decreased carbon limitation of litter respiration in a mortality-affected pinon-juniper woodland

Treesearch

Erin Berryman; John D. Marshall; Thom Rahn; Marcie Litvak; John Butnor

2013-01-01

Microbial respiration depends on microclimatic variables and carbon (C) substrate availability, all of which are altered when ecosystems experience major disturbance. Widespread tree mortality, currently affecting pinon-juniper ecosystems in southwestern North America, may affect C substrate availability in several ways, for example, via litterfall pulses and loss of...

Biomass consumption during prescribed fires in big sagebrush ecosystems

Treesearch

Clinton S. Wright; Susan J. Prichard

2006-01-01

Big sagebrush (Artemisia tridentata) ecosystems typically experience stand replacing fires during which some or all of the ignited biomass is consumed. Biomass consumption is directly related to the energy released during a fire, and is an important factor that determines smoke production and the effects of fire on other resources. Consumption of...

A test of critical thresholds and their indicators in a desertification-prone ecosystem: more resilience than we thought

USDA-ARS?s Scientific Manuscript database

Theoretical models predict that dryland ecosystems can cross critical thresholds after which vegetation loss is independent of initial drivers, but experimental data are nonexistent. We used a long-term (13 year) pulse-perturbation experiment featuring heavy grazing and shrub removal to determine i...

The Moquah Barrens Research Natural Area: Loss of a pine barrens ecosystem

USGS Publications Warehouse

Ribic, Christine

2017-01-01

The Moquah Barrens Research Natural Area (RNA) was established by the Chequamegon National Forest and the Lakes States Forest Experiment Station in 1935 with a research objective well-suited to the needs of the Forest Service and the scientific understanding of ecosystem function prevalent at the time of establishment. The original research plan was never implemented, which led to a joint Forest-Station decision in 1956 to disestablish the RNA. However, that decision was never implemented. A series of management decisions made after 1956 led to the loss of the pine barrens ecosystem originally encompassed by the RNA. This loss is not irretrievable and the work necessary to recover the original ecosystem is possible under existing RNA management guidelines. The experience of the Moquah Barrens RNA can be used by the Forest Service to improve overall management of the entire system of research natural areas. Two main areas of opportunity are identified: 1) implement an improved approach to managing official records associated with RNAs; and 2) adopt a management framework suitable for long-term ecological projects.

Hemigrapsus sanguineus in Long Island salt marshes: experimental evaluation of the interactions between an invasive crab and resident ecosystem engineers

PubMed Central

Fournier, Alexa M.; Furman, Bradley T.; Carroll, John M.

2014-01-01

The invasive Asian shore crab, Hemigrapsus sanguineus, has recently been observed occupying salt marshes, a novel environment for this crab species. As it invades this new habitat, it is likely to interact with a number of important salt marsh species. To understand the potential effects of H. sanguineus on this ecosystem, interactions between this invasive crab and important salt marsh ecosystem engineers were examined. Laboratory experiments demonstrated competition for burrows between H. sanguineus and the native fiddler crab, Uca pugilator. Results indicate that H. sanguineus is able to displace an established fiddler crab from its burrow. Feeding experiments revealed that the presence of H. sanguineus has a significantly negative impact on the number as well as the biomass of ribbed mussels (Geukensia demissa) consumed by the green crab, Carcinus maenas, although this only occurred at high predator densities. In addition, when both crabs foraged together, there was a significant shift in the size of mussels consumed. These interactions suggests that H. sanguineus may have long-term impacts and wide-ranging negative effects on the saltmarsh ecosystem. PMID:25071995

Hemigrapsus sanguineus in Long Island salt marshes: experimental evaluation of the interactions between an invasive crab and resident ecosystem engineers.

PubMed

Peterson, Bradley J; Fournier, Alexa M; Furman, Bradley T; Carroll, John M

2014-01-01

The invasive Asian shore crab, Hemigrapsus sanguineus, has recently been observed occupying salt marshes, a novel environment for this crab species. As it invades this new habitat, it is likely to interact with a number of important salt marsh species. To understand the potential effects of H. sanguineus on this ecosystem, interactions between this invasive crab and important salt marsh ecosystem engineers were examined. Laboratory experiments demonstrated competition for burrows between H. sanguineus and the native fiddler crab, Uca pugilator. Results indicate that H. sanguineus is able to displace an established fiddler crab from its burrow. Feeding experiments revealed that the presence of H. sanguineus has a significantly negative impact on the number as well as the biomass of ribbed mussels (Geukensia demissa) consumed by the green crab, Carcinus maenas, although this only occurred at high predator densities. In addition, when both crabs foraged together, there was a significant shift in the size of mussels consumed. These interactions suggests that H. sanguineus may have long-term impacts and wide-ranging negative effects on the saltmarsh ecosystem.

Bream (Abramis brama (L.)) as zoogeomorphic agents and ecosystem engineers: Implications for fine sediment transport in lowland rivers

NASA Astrophysics Data System (ADS)

Smith, James; Rice, Stephen; Hodgkins, Richard

2017-04-01

Despite increasing recognition that animals play important roles in geomorphological systems (zoogeomorphology), with important ecological implications for the animals and their ecosystems (ecosystem engineering), sediment transport continues to be regarded as an abiotic process. This research challenges that orthodoxy by investigating the biotic processes associated with bioturbation in rivers caused by feeding bream (Abramis brama (L.)) and quantifying their impact on fine sediment suspension and sediment yield. Experiments in lakes have demonstrated that bream negatively influence ecosystem dynamics through bottom up mechanisms as a result of physical bioturbation caused by benthivorous feeding. Although this level of bioturbation, and thus sediment entrainment, can alter the fundamental biogeochemical cycles and food web dynamics in lentic ecosystems, research is yet to assess this potential effect in riverine ecosystems or evaluate this bioturbation mechanism as a driver of fluvial sediment flux - even though they are common in rivers across mainland Europe. A series of ex-situ mesocosm experiments have investigated the controls of fine sediment entrainment by bream, assessing the roles of both biomass (size and number) and food density on suspended sediment concentration and turbidity. Bream create large volumes of suspended sediment during feeding (highest recorded turbidity 1172 NTU) and there are significant (p < 0.001) increases in turbidity associated with each experimental parameter: number of fish, fish size and food density. Supplementary experiments have assessed bream as ecosystem engineers in the presence of the congener species, roach (Rutilus rutilus (L.)), which share the same ecological niche. In the presence of roach, the impact of bream on turbidity increased by an average of 120% (6.6 NTU to 15 NTU) and increased further at the 90th percentile by 240% (32 NTU to 110 NTU). In light of these findings, the extensive geographical distribution of bream and the observation that shoals of bream commonly exceed one thousand individuals, it is plausible that bream are an important biological constituent of the fine sediment cascade within riverine systems. Complementary field work is underway to quantify the frequency-magnitude characteristics of the fine sediment plumes that feeding shoals of bream generate in lowland UK rivers.

Model-experiment synthesis at two FACE sites in the southeastern US. Forest ecosystem responses to elevated CO[2]. (Invited)

NASA Astrophysics Data System (ADS)

Walker, A. P.; Zaehle, S.; De Kauwe, M. G.; Medlyn, B. E.; Dietze, M.; Hickler, T.; Iversen, C. M.; Jain, A. K.; Luo, Y.; McCarthy, H. R.; Parton, W. J.; Prentice, C.; Thornton, P. E.; Wang, S.; Wang, Y.; Warlind, D.; Warren, J.; Weng, E.; Hanson, P. J.; Oren, R.; Norby, R. J.

2013-12-01

Ecosystem observations from two long-term Free-Air CO[2] Enrichment (FACE) experiments (Duke forest and Oak Ridge forest) were used to evaluate the assumptions of 11 terrestrial ecosystem models and the consequences of those assumptions for the responses of ecosystem water, carbon (C) and nitrogen (N) fluxes to elevated CO[2] (eCO[2]). Nitrogen dynamics were the main constraint on simulated productivity responses to eCO[2]. At Oak Ridge some models reproduced the declining response of C and N fluxes, while at Duke none of the models were able to maintain the observed sustained responses. C and N cycles are coupled through a number of complex interactions, which causes uncertainty in model simulations in multiple ways. Nonetheless, the major difference between models and experiments was a larger than observed increase in N-use efficiency and lower than observed response of N uptake. The results indicate that at Duke there were mechanisms by which trees accessed additional N in response to eCO[2] that were not represented in the ecosystem models, and which did not operate with the same efficiency at Oak Ridge. Sequestration of the additional productivity under eCO[2] into forest biomass depended largely on C allocation. Allocation assumptions were classified into three main categories--fixed partitioning coefficients, functional relationships and a partial (leaf allocation only) optimisation. The assumption which best constrained model results was a functional relationship between leaf area and sapwood area (pipe-model) and increased root allocation when nitrogen or water were limiting. Both, productivity and allocation responses to eCO[2] determined the ecosystem-level response of LAI, which together with the response of stomatal conductance (and hence water-use efficiency; WUE) determined the ecosystem response of transpiration. Differences in the WUE response across models were related to the representation of the relationship of stomatal conductance to CO[2] and the relative importance of the combined boundary and aerodynamic resistances in the total resistance to leaf-atmosphere water transport.

Trait-based Modeling Reveals How Plankton Biodiversity-Ecosystem Function (BEF) Relationships Depend on Environmental Variability

NASA Astrophysics Data System (ADS)

Smith, S. L.; Chen, B.; Vallina, S. M.

2017-12-01

Biodiversity-Ecosystem Function (BEF) relationships, which are most commonly quantified in terms of productivity or total biomass yield, are known to depend on the timescale of the experiment or field study, both for terrestrial plants and phytoplankton, which have each been widely studied as model ecosystems. Although many BEF relationships are positive (i.e., increasing biodiversity enhances function), in some cases there is an optimal intermediate diversity level (i.e., a uni-modal relationship), and in other cases productivity decreases with certain measures of biodiversity. These differences in BEF relationships cannot be reconciled merely by differences in the timescale of experiments. We will present results from simulation experiments applying recently developed trait-based models of phytoplankton communities and ecosystems, using the `adaptive dynamics' framework to represent continuous distributions of size and other key functional traits. Controlled simulation experiments were conducted with different levels of phytoplankton size-diversity, which through trait-size correlations implicitly represents functional-diversity. One recent study applied a theoretical box model for idealized simulations at different frequencies of disturbance. This revealed how the shapes of BEF relationships depend systematically on the frequency of disturbance and associated nutrient supply. We will also present more recent results obtained using a trait-based plankton ecosystem model embedded in a three-dimensional ocean model applied to the North Pacific. This reveals essentially the same pattern in a spatially explicit model with more realistic environmental forcing. In the relatively more variable subarctic, productivity tends to increase with the size (and hence functional) diversity of phytoplankton, whereas productivity tends to decrease slightly with increasing size-diversity in the relatively calm subtropics. Continuous trait-based models can capture essential features of BEF relationships, while requiring far fewer calculations compared to typical plankton diversity models that explicitly simulate a great many idealized species.

Linking global-change induced shifts in soil nitrogen cycling with the abundance of key microorganisms

NASA Astrophysics Data System (ADS)

Carey, C.; Eviner, V.; Beman, M.; Hart, S. C.

2013-12-01

Since western colonization, the ecology of California has seen marked transformations. In particular, invasion of terrestrial ecosystems by exotic plants has altered plant community composition, disturbances, soil hydrologic regimes, and nutrient cycling. In addition, as a result of fertilization and combustion of fossil fuels, California experiences some of the highest nitrogen (N) deposition rates in the country. Land use has also changed with the introduction of domestic livestock grazing about 250 years ago. Currently, approximately 32% of land in California experiences grazing pressure. These ecological changes likely affect the ecosystems of California simultaneously. However, with multifactor global change experiments in their infancy, little is known about potential interactive effects on ecosystem structure and function. Our study measured the response of soil N dynamics to a unique combination of treatments: invasion by exotic plants (Aegilops triuncialis and Taeniatherum caput-medusae), elevated N additions, and simulated cattle grazing (aboveground vegetation removal). In addition, we quantified the abundance of key functional genes involved in nitrification (amoA) and denitrification (nirS/nirK) in order to gain a mechanistic insight into changes in ecosystem functioning. We found that, while responses of soil N pools and processes to global change factors tend to be dominated by main effects, interactions among factors can substantially alter the overall response of the ecosystem. For instance, N additions increased potential nitrification and pools of total inorganic N (TIN; NH4+ and NO3-); when N additions and grazing were combined, however, nitrification potentials and TIN decreased to those of ambient N (control) levels. Additionally, neither N additions nor simulated grazing independently affected soil microbial biomass of invaded plots; yet, when combined, the microbial biomass increased significantly. Our results help to provide a better understanding of the regulatory role of the soil microbial community in terrestrial N cycling and also help to improve our understanding of the controls on global change-induced shifts in ecosystem functioning.

Mapping the ecosystem service delivery chain: Capacity, flow, and demand pertaining to aesthetic experiences in mountain landscapes.

PubMed

Egarter Vigl, Lukas; Depellegrin, Daniel; Pereira, Paulo; de Groot, Rudolf; Tappeiner, Ulrike

2017-01-01

Accounting for the spatial connectivity between the provision of ecosystem services (ES) and their beneficiaries (supply-benefit chain) is fundamental to understanding ecosystem functioning and its management. However, the interrelationships of the specific chain links within ecosystems and the actual benefits that flow from natural landscapes to surrounding land have rarely been analyzed. We present a spatially explicit model for the analysis of one cultural ecosystem service (aesthetic experience), which integrates the complete ecosystem service delivery chain for Puez-Geisler Nature Park (Italy): (1) The potential service stock (ES capacity) relies on an expert-based land use ranking matrix, (2) the actual supply (ES flow) is based on visibility properties of observation points along recreational routes, (3) the beneficiaries of the service (ES demand) are derived from socioeconomic data as a measure of the visitation rate to the recreation location, and (4) the supply-demand relationship (ES budget) addresses the spatially explicit oversupply and undersupply of ES. The results indicate that potential ES stocks are substantially higher in core and buffer zones of protected areas than in surrounding land owing to the specific landscape composition. ES flow maps reveal service delivery to 80% of the total area studied, with the highest actual service supply to locations with long and open vistas. ES beneficiary analyses show the highest demand for aesthetic experiences in all-season tourist destinations like Val Badia and Val Gardena, where both recreational amenity and overnight stays are equally high. ES budget maps identify ES hot and cold spots in terms of ES delivery, and they highlight ES undersupply in nature protection buffer zones although they are characterized by highest ES capacity. We show how decision/policy makers can use the presented methodology to plan landscape protection measures and develop specific regulation strategies for visitors based on the ES delivery chain concept. Copyright © 2016 Elsevier B.V. All rights reserved.

Global-change drivers of ecosystem functioning modulated by natural variability and saturating responses.

PubMed

Flombaum, Pedro; Yahdjian, Laura; Sala, Osvaldo E

2017-02-01

Humans are altering global environment at an unprecedented rate through changes in biodiversity, climate, nitrogen cycle, and land use. To address their effects on ecosystem functioning, experiments most frequently explore one driver at a time and control as many confounding factors as possible. Yet, which driver exerts the largest influence on ecosystem functioning and whether their relative importance changes among systems remain unclear. We analyzed experiments in the Patagonian steppe that evaluated the aboveground net primary production (ANPP) response to manipulated gradients of species richness, precipitation, temperature, nitrogen fertilization (N), and grazing intensity. We compared the effect on ANPP relative to ambient conditions considering intensity and direction of manipulations for each driver. The ranking of responses to drivers with comparable manipulation intensity was as follows: biodiversity>grazing>precipitation>N. For a similar intensity of manipulation, the effect of biodiversity loss was 4.0, 3.6, and 1.5, times larger than N deposition, decreased precipitation, and increased grazing intensity. We interpreted our results considering two hypotheses. First, the response of ANPP to changes in precipitation and biodiversity is saturating, so we expected larger effects when the driver was reduced, relative to ambient conditions, than when it was increased. Experimental manipulations that reduced ambient levels had larger effects than those that increased them. Second, the sensitivity of ANPP to each driver is inversely related to the natural variability of the driver. In Patagonia, the ranking of natural variability of drivers is as follows: precipitation>grazing>temperature>biodiversity>N. So, in general, the ecosystem was most sensitive to drivers that varied the least. Comparable results from Cedar Creek (MN) support both hypotheses and suggest that sensitivity to drivers varies among ecosystem types. Given the importance of understanding ecosystem sensitivity to predict global-change impacts, it is necessary to design new experiments located in regions with contrasting natural variability and that include the full range of drivers. © 2016 John Wiley & Sons Ltd.

A bottom-up evolution of terrestrial ecosystem modeling theory, and ideas toward global vegetation modeling

NASA Technical Reports Server (NTRS)

Running, Steven W.

1992-01-01

A primary purpose of this review is to convey lessons learned in the development of a forest ecosystem modeling approach, from it origins in 1973 as a single-tree water balance model to the current regional applications. The second intent is to use this accumulated experience to offer ideas of how terrestrial ecosystem modeling can be taken to the global scale: earth systems modeling. A logic is suggested where mechanistic ecosystem models are not themselves operated globally, but rather are used to 'calibrate' much simplified models, primarily driven by remote sensing, that could be implemented in a semiautomated way globally, and in principle could interface with atmospheric general circulation models (GCM's).

Quantifying Direct and Indirect Effects of Elevated CO2 on Ecosystem Response

NASA Astrophysics Data System (ADS)

Fatichi, S.; Leuzinger, S.; Paschalis, A.; Donnellan-Barraclough, A.; Hovenden, M. J.; Langley, J. A.

2015-12-01

Increasing concentrations of atmospheric carbon dioxide are expected to affect carbon assimilation, evapotranspiration (ET) and ultimately plant growth. Direct leaf biochemical effects have been widely investigated, while indirect effects, although documented, are very difficult to quantify in experiments. We hypothesize that the interaction of direct and indirect effects is a possible reason for conflicting results concerning the magnitude of CO2 fertilization effects across different climates and ecosystems. A mechanistic ecohydrological model (Tethys-Chloris) is used to investigate the relative contribution of direct (through plant physiology) and indirect (via stomatal closure and thus soil moisture, and changes in Leaf Area Index, LAI) effects of elevated CO2 across a number of ecosystems. We specifically ask in which ecosystems and climate indirect effects are expected to be largest. Data and boundary conditions from flux-towers and free air CO2 enrichment (FACE) experiments are used to force the model and evaluate its performance. Numerical results suggest that indirect effects of elevated CO2, through water savings and increased LAI, are very significant and sometimes larger than direct effects. Indirect effects tend to be considerably larger in water-limited ecosystems, while direct effects correlate positively with mean air temperature. Increasing CO2 from 375 to 550 ppm causes a total effect on Net Primary Production in the order of 15 to 40% and on ET from 0 to -8%, depending on climate and ecosystem type. The total CO2 effect has a significant negative correlation with the wetness index and positive correlation with vapor pressure deficit. These results provide a more general mechanistic understanding of relatively short-term (less than 20 years) implications of elevated CO2 on ecosystem response and suggest plausible magnitudes for the expected changes.

Increased resource use efficiency amplifies positive response of aquatic primary production to experimental warming.

PubMed

Hood, James M; Benstead, Jonathan P; Cross, Wyatt F; Huryn, Alexander D; Johnson, Philip W; Gíslason, Gísli M; Junker, James R; Nelson, Daniel; Ólafsson, Jón S; Tran, Chau

2018-03-01

Climate warming is affecting the structure and function of river ecosystems, including their role in transforming and transporting carbon (C), nitrogen (N), and phosphorus (P). Predicting how river ecosystems respond to warming has been hindered by a dearth of information about how otherwise well-studied physiological responses to temperature scale from organismal to ecosystem levels. We conducted an ecosystem-level temperature manipulation to quantify how coupling of stream ecosystem metabolism and nutrient uptake responded to a realistic warming scenario. A ~3.3°C increase in mean water temperature altered coupling of C, N, and P fluxes in ways inconsistent with single-species laboratory experiments. Net primary production tripled during the year of experimental warming, while whole-stream N and P uptake rates did not change, resulting in 289% and 281% increases in autotrophic dissolved inorganic N and P use efficiency (UE), respectively. Increased ecosystem production was a product of unexpectedly large increases in mass-specific net primary production and autotroph biomass, supported by (i) combined increases in resource availability (via N mineralization and N 2 fixation) and (ii) elevated resource use efficiency, the latter associated with changes in community structure. These large changes in C and nutrient cycling could not have been predicted from the physiological effects of temperature alone. Our experiment provides clear ecosystem-level evidence that warming can shift the balance between C and nutrient cycling in rivers, demonstrating that warming will alter the important role of in-stream processes in C, N, and P transformations. Moreover, our results reveal a key role for nutrient supply and use efficiency in mediating responses of primary producers to climate warming. © 2017 John Wiley & Sons Ltd.

Plant functional diversity increases grassland productivity-related water vapor fluxes: an Ecotron and modeling approach.

PubMed

Milcu, Alexandru; Eugster, Werner; Bachmann, Dörte; Guderle, Marcus; Roscher, Christiane; Gockele, Annette; Landais, Damien; Ravel, Olivier; Gessler, Arthur; Lange, Markus; Ebeling, Anne; Weisser, Wolfgang W; Roy, Jacques; Hildebrandt, Anke; Buchmann, Nina

2016-08-01

The impact of species richness and functional diversity of plants on ecosystem water vapor fluxes has been little investigated. To address this knowledge gap, we combined a lysimeter setup in a controlled environment facility (Ecotron) with large ecosystem samples/monoliths originating from a long-term biodiversity experiment (The Jena Experiment) and a modeling approach. Our goals were (1) quantifying the impact of plant species richness (four vs. 16 species) on day- and nighttime ecosystem water vapor fluxes; (2) partitioning ecosystem evapotranspiration into evaporation and plant transpiration using the Shuttleworth and Wallace (SW) energy partitioning model; and (3) identifying the most parsimonious predictors of water vapor fluxes using plant functional-trait-based metrics such as functional diversity and community weighted means. Daytime measured and modeled evapotranspiration were significantly higher in the higher plant diversity treatment, suggesting increased water acquisition. The SW model suggests that, at low plant species richness, a higher proportion of the available energy was diverted to evaporation (a non-productive flux), while, at higher species richness, the proportion of ecosystem transpiration (a productivity-related water flux) increased. While it is well established that LAI controls ecosystem transpiration, here we also identified that the diversity of leaf nitrogen concentration among species in a community is a consistent predictor of ecosystem water vapor fluxes during daytime. The results provide evidence that, at the peak of the growing season, higher leaf area index (LAI) and lower percentage of bare ground at high plant diversity diverts more of the available water to transpiration, a flux closely coupled with photosynthesis and productivity. Higher rates of transpiration presumably contribute to the positive effect of diversity on productivity. © 2016 by the Ecological Society of America.

Inter-annual variability of carbon fluxes in temperate forest ecosystems: effects of biotic and abiotic factors

NASA Astrophysics Data System (ADS)

Chen, M.; Keenan, T. F.; Hufkens, K.; Munger, J. W.; Bohrer, G.; Brzostek, E. R.; Richardson, A. D.

2014-12-01

Carbon dynamics in terrestrial ecosystems are influenced by both abiotic and biotic factors. Abiotic factors, such as variation in meteorological conditions, directly drive biophysical and biogeochemical processes; biotic factors, referring to the inherent properties of the ecosystem components, reflect the internal regulating effects including temporal dynamics and memory. The magnitude of the effect of abiotic and biotic factors on forest ecosystem carbon exchange has been suggested to vary at different time scales. In this study, we design and conduct a model-data fusion experiment to investigate the role and relative importance of the biotic and abiotic factors for inter-annual variability of the net ecosystem CO2 exchange (NEE) of temperate deciduous forest ecosystems in the Northeastern US. A process-based model (FöBAAR) is parameterized at four eddy-covariance sites using all available flux and biometric measurements. We conducted a "transplant" modeling experiment, that is, cross- site and parameter simulations with different combinations of site meteorology and parameters. Using wavelet analysis and variance partitioning techniques, analysis of model predictions identifies both spatial variant and spatially invariant parameters. Variability of NEE was primarily modulated by gross primary productivity (GPP), with relative contributions varying from hourly to yearly time scales. The inter-annual variability of GPP and NEE is more regulated by meteorological forcing, but spatial variability in certain model parameters (biotic response) has more substantial effects on the inter-annual variability of ecosystem respiration (Reco) through the effects on carbon pools. Both the biotic and abiotic factors play significant roles in modulating the spatial and temporal variability in terrestrial carbon cycling in the region. Together, our study quantifies the relative importance of both, and calls for better understanding of them to better predict regional CO2 exchanges.

Global changes alter soil fungal communities and alter rates of organic matter decomposition

NASA Astrophysics Data System (ADS)

Moore, J.; Frey, S. D.

2016-12-01

Global changes - such as warming, more frequent and severe droughts, increasing atmospheric CO2, and increasing nitrogen (N) deposition rates - are altering ecosystem processes. The balance between soil carbon (C) accumulation and decomposition is determined in large part by the activity and biomass of detrital organisms, namely soil fungi, and yet their sensitivity to global changes remains unresolved. We present results from a meta-analysis of 200+ studies spanning manipulative and observational field experiments to quantify fungal responses to global change and expected consequences for ecosystem C dynamics. Warming altered the functional soil microbial community by reducing the ratio of fungi to bacteria (f:b) total fungal biomass. Additionally, warming reduced lignolytic enzyme activity generally by one-third. Simulated N deposition affected f:b differently than warming, but the effect on fungal biomass and activity was similar. The effect of N-enrichment on f:b was contingent upon ecosystem type; f:b increased in alpine meadows and heathlands but decreased in temperate forests following N-enrichment. Across ecosystems, fungal biomass marginally declined by 8% in N-enriched soils. In general, N-enrichment reduced fungal lignolytic enzyme activity, which could explain why soil C accumulates in some ecosystems following warming and N-enrichment. Several global change experiments have reported the surprising result that soil C builds up following increases in temperature and N deposition rates. While site-specific studies have examined the role of soil fungi in ecosystem responses to global change, we present the first meta-analysis documenting general patterns of global change impacts on soil fungal communities, biomass, and activity. In sum, we provide evidence that soil microbial community shifts and activity plays a large part in ecosystem responses to global changes, and have the potential to alter the magnitude of the C-climate feedback.

Payments discourage coordination in ecosystem services provision: evidence from behavioral experiments in Southeast Asia

NASA Astrophysics Data System (ADS)

Bell, Andrew; Zhang, Wei

2016-11-01

The contribution of synthetic pesticides to closing yield gaps around the world is undeniable; however, their use is also a classic double-edged sword. Beyond the well-recognized social costs (e.g., pollution to soil and water, and health effects both on consumers and other species) there are also private costs on farmers beyond the direct costs of inputs, associated with elevated risks of both acute and chronic damage to farmers’ health, and with the destruction of populations of beneficial organisms. Managing agricultural land use to enhance natural pest control services (also called mobile agent-based ecosystem services or MABES) holds promise to reduce this growing reliance on pesticides, though it too carries costs. In particular, uncertainty in crop yield due to pest damages, as well as the need to coordinate pesticide use with neighboring farms, can be important obstacles to establishing the longer-term public good of natural pest regulation. Current thinking on promoting ecosystem services suggests that payments or other economic incentives are a good fit for the promotion of public good ecosystem services such as MABES. We undertook a framed field experiment to examine the role of subsidies for non-crop habitat in improving insect-based ecosystem services in two separate samples in Southeast Asia—Cambodia and Vietnam. Our central finding is that these two contexts are not poised equally to benefit from incentives promoting MABES, and in fact may be left worse off by payments schemes. As the study and practice of payments for ecosystem services programs grows, this finding provides an important qualifier on recent theory supporting the use of payments to promote public good ecosystem services—where the nature of the coordination problem is complex and nonlinear, farm systems can be made worse off by being encouraged to attempt it.

Avian Conservation Practices Strengthen Ecosystem Services in California Vineyards

PubMed Central

Jedlicka, Julie A.; Greenberg, Russell; Letourneau, Deborah K.

2011-01-01

Insectivorous Western Bluebirds (Sialia mexicana) occupy vineyard nest boxes established by California winegrape growers who want to encourage avian conservation. Experimentally, the provision of available nest sites serves as an alternative to exclosure methods for isolating the potential ecosystem services provided by foraging birds. We compared the abundance and species richness of avian foragers and removal rates of sentinel prey in treatments with songbird nest boxes and controls without nest boxes. The average species richness of avian insectivores increased by over 50 percent compared to controls. Insectivorous bird density nearly quadrupled, primarily due to a tenfold increase in Western Bluebird abundance. In contrast, there was no significant difference in the abundance of omnivorous or granivorous bird species some of which opportunistically forage on grapes. In a sentinel prey experiment, 2.4 times more live beet armyworms (Spodoptera exigua) were removed in the nest box treatment than in the control. As an estimate of the maximum foraging services provided by insectivorous birds, we found that larval removal rates measured immediately below occupied boxes averaged 3.5 times greater than in the control. Consequently the presence of Western Bluebirds in vineyard nest boxes strengthened ecosystem services to winegrape growers, illustrating a benefit of agroecological conservation practices. Predator addition and sentinel prey experiments lack some disadvantages of predator exclusion experiments and were robust methodologies for detecting ecosystem services. PMID:22096555

Avian conservation practices strengthen ecosystem services in California vineyards.

PubMed

Jedlicka, Julie A; Greenberg, Russell; Letourneau, Deborah K

2011-01-01

Insectivorous Western Bluebirds (Sialia mexicana) occupy vineyard nest boxes established by California winegrape growers who want to encourage avian conservation. Experimentally, the provision of available nest sites serves as an alternative to exclosure methods for isolating the potential ecosystem services provided by foraging birds. We compared the abundance and species richness of avian foragers and removal rates of sentinel prey in treatments with songbird nest boxes and controls without nest boxes. The average species richness of avian insectivores increased by over 50 percent compared to controls. Insectivorous bird density nearly quadrupled, primarily due to a tenfold increase in Western Bluebird abundance. In contrast, there was no significant difference in the abundance of omnivorous or granivorous bird species some of which opportunistically forage on grapes. In a sentinel prey experiment, 2.4 times more live beet armyworms (Spodoptera exigua) were removed in the nest box treatment than in the control. As an estimate of the maximum foraging services provided by insectivorous birds, we found that larval removal rates measured immediately below occupied boxes averaged 3.5 times greater than in the control. Consequently the presence of Western Bluebirds in vineyard nest boxes strengthened ecosystem services to winegrape growers, illustrating a benefit of agroecological conservation practices. Predator addition and sentinel prey experiments lack some disadvantages of predator exclusion experiments and were robust methodologies for detecting ecosystem services.

Local loss and spatial homogenization of plant diversity reduce ecosystem multifunctionality.

PubMed

Hautier, Yann; Isbell, Forest; Borer, Elizabeth T; Seabloom, Eric W; Harpole, W Stanley; Lind, Eric M; MacDougall, Andrew S; Stevens, Carly J; Adler, Peter B; Alberti, Juan; Bakker, Jonathan D; Brudvig, Lars A; Buckley, Yvonne M; Cadotte, Marc; Caldeira, Maria C; Chaneton, Enrique J; Chu, Chengjin; Daleo, Pedro; Dickman, Christopher R; Dwyer, John M; Eskelinen, Anu; Fay, Philip A; Firn, Jennifer; Hagenah, Nicole; Hillebrand, Helmut; Iribarne, Oscar; Kirkman, Kevin P; Knops, Johannes M H; La Pierre, Kimberly J; McCulley, Rebecca L; Morgan, John W; Pärtel, Meelis; Pascual, Jesus; Price, Jodi N; Prober, Suzanne M; Risch, Anita C; Sankaran, Mahesh; Schuetz, Martin; Standish, Rachel J; Virtanen, Risto; Wardle, Glenda M; Yahdjian, Laura; Hector, Andy

2018-01-01

Biodiversity is declining in many local communities while also becoming increasingly homogenized across space. Experiments show that local plant species loss reduces ecosystem functioning and services, but the role of spatial homogenization of community composition and the potential interaction between diversity at different scales in maintaining ecosystem functioning remains unclear, especially when many functions are considered (ecosystem multifunctionality). We present an analysis of eight ecosystem functions measured in 65 grasslands worldwide. We find that more diverse grasslands-those with both species-rich local communities (α-diversity) and large compositional differences among localities (β-diversity)-had higher levels of multifunctionality. Moreover, α- and β-diversity synergistically affected multifunctionality, with higher levels of diversity at one scale amplifying the contribution to ecological functions at the other scale. The identity of species influencing ecosystem functioning differed among functions and across local communities, explaining why more diverse grasslands maintained greater functionality when more functions and localities were considered. These results were robust to variation in environmental drivers. Our findings reveal that plant diversity, at both local and landscape scales, contributes to the maintenance of multiple ecosystem services provided by grasslands. Preserving ecosystem functioning therefore requires conservation of biodiversity both within and among ecological communities.

Bottom-up biodiversity effects increase resource subsidy flux between ecosystems.

PubMed

Allen, Daniel C; Vaughn, Caryn C; Kelly, Jeffrey F; Cooper, Joshua T; Engel, Michael H

2012-10-01

Although biodiversity can increase ecosystem productivity and adjacent ecosystems are often linked by resource flows between them, the relationship between biodiversity and resource subsidies is not well understood. Here we test the influence of biodiversity on resource subsidy flux by manipulating freshwater mussel species richness and documenting the effects on a trophic cascade from aquatic to terrestrial ecosystems. In a mesocosm experiment, mussel effects on algae were linked through stable isotope analyses to mussel-derived nitrogen subsidies, but mussel biodiversity effects on algal accumulation were not significant. In contrast, mussel biodiversity significantly increased aquatic insect emergence rates, because aquatic insects were responding to mussel-induced changes in algal community structure instead of algal accumulation. In turn, mussel biodiversity also significantly increased terrestrial spider abundance as spiders tracked increases in aquatic insect prey after a reproduction event. In a comparative field study, we found that sites with greater mussel species richness had higher aquatic insect emergence rates. These results show that, because food webs in adjacent ecosystems are often linked, biodiversity effects in one ecosystem can influence adjacent ecosystems as well.

Modeled interactive effects of precipitation, temperature, and [CO2] on ecosystem carbon and water dynamics in different climatic zones

Treesearch

Yiqi Luo; Dieter Gerten; Guerric Le Maire; William J. Parton; Ensheng Weng; Xuhui Zhou; Cindy Keough; Claus Beier; Philippe Ciais; Wolfgang Cramer; Jeffrey S. Dukes; Bridget Emmett; Paul J. Hanson; Alan Knapp; Sune Linder; Dan Nepstad; Lindsey. Rustad

2008-01-01

Interactive effects of multiple global change factors on ecosystem processes are complex. It is relatively expensive to explore those interactions in manipulative experiments. We conducted a modeling analysis to identify potentially important interactions and to stimulate hypothesis formulation for experimental research. Four models were used to quantify interactive...

Relative abundance and species richness of terrestrial salamanders on hardwood ecosystem experiment sites before harvesting

Treesearch

Jami E. MacNeil; Rod N. Williams

2013-01-01

Terrestrial salamanders are ideal indicators of forest ecosystem integrity due to their abundance, their role in nutrient cycling, and their sensitivity to environmental change. To understand better how terrestrial salamanders are affected by forest management practices, we monitored species diversity and abundance before implementation of timber harvests within the...

Proceedings of the second Missouri Ozark Forest Ecosystem Project Symposium: Post-treatment results of the landscape experiment

Treesearch

S.R. Shifley; J.M., eds. Kabrick

2002-01-01

Presents the short-term effects of even-aged, uneven-aged, and no-harvest management on forest ecosystems included in the Missouri Ozark Forest Project (MOFEP). Individual papers address study design, site history, species diversity, genetic diversity, woody vegetation, ground layer vegetation, stump sprouting, tree cavities, logging disturbance, avian communities,...

A decade of belowground reorganization following multiple disturbances in a subtropical wet forest

Treesearch

Y.A. Teh; W.L. Silver; F.N. Scatena

2009-01-01

Humid tropical forests are dynamic ecosystems that experience multiple and overlapping disturbance events that vary in frequency, intensity, and spatial extent. Here we report the results of a 10-year study investigating the effects of forest clearing and multiple hurricanes on ecosystem carbon reservoirs, nutrient pools and vegetation. The aboveground plant community...

A CO2 concentration gradient facility for testing CO2 enrichment and soil effects on grassland ecosystem function

USDA-ARS?s Scientific Manuscript database

Continuing increases in atmospheric CO2 concentrations mandate techniques for examining impacts on terrestrial ecosystems. Most experiments examine only two or a few levels of CO2 concentration and a single soil type, but if CO2 can be varied as a gradient from subambient to superambient concentra...

New Technology, New Pedagogy? Employing Video Podcasts in Learning and Teaching about Exotic Ecosystems

ERIC Educational Resources Information Center

Hill, Jennifer L.; Nelson, Amanda

2011-01-01

This paper examines the experiences of undergraduate university students in response to the employment of video podcasts to support learning and teaching about exotic ecosystems. Six, 15-20-minute podcasts were made accessible to students through a virtual learning environment, either online or to download to mobile technology. The students were…

Coupled cycling of dissolved organic nitrogen and carbon in a forest stream

Treesearch

E.N. Jack Brookshire; H. Maurice Valett; Steven A. Thomas; Jackson R. Webster

2005-01-01

Dissolved organic nitrogen (DON) is an abundant but poorly understood pool of N in many ecosystems. We assessed DON cycling in a N-limited headwater forest stream via whole-ecosystem additions of dissolved inorganic nitrogen (DIN) and labile dissolved organic matter (DOM), hydrologic transport and biogeochemical modeling, and laboratory experiments with native...

Programmatic background, site description, experimental approach and treatment, and natural disturbances

Treesearch

Wayne T. Swank; Jackson Webster

2014-01-01

This volume is a synthesis of a long-term interdisciplinary study of watershed ecosystem responses to a forest-management disturbance. Specifically, a commercial clearcut cable logging experiment was initiated on Watershed 7 (WS 7) at the Coweeta Hydrologic Laboratory in 1975 to elucidate ecosystem structure and function by testing hypotheses associated with the...

Carbon dioxide fluxes in a central hardwoods oak-hickory forest ecosystem

Treesearch

Stephen G. Pallardy; Lianhong Gu; Paul J. Hanson; Tilden Myers; Stan D. Wullschleger; Bai Yang; Jeffery S. Riggs; Kevin P. Hosman; Mark Heuer

2007-01-01

A long-term experiment to measure carbon and water fluxes was initiated in 2004 as part of the Ameriflux network in a second-growth oak-hickory forest in central Missouri. Ecosystem-scale (~ 1 km2) canopy gas exchange (measured by eddy-covariance methods), vertical CO2 profile sampling and soil respiration along with...

Strengthening Collaborative Capacity: Experiences from a Short, Intensive Field Course on Ecosystems, Health and Society

ERIC Educational Resources Information Center

Parkes, Margot W.; Saint-Charles, Johanne; Cole, Donald C.; Gislason, Maya; Hicks, Elisabeth; Le Bourdais, Courtney; McKellar, Kaileah A.; St-Cyr Bouchard, Maude

2017-01-01

A key capacity for engagement in the emerging field of ecohealth is the ability to work collaboratively. Between 2008 and 2010, the Canadian Community of Practice in Ecosystem Approaches to Health collectively designed and delivered three foundational, intensive, field courses. This paper presents findings derived from both quantitative and…

Water chemistry of Rocky Mountain Front Range aquatic ecosystems

Treesearch

Robert C. Musselman; Laura Hudnell; Mark W. Williams; Richard A. Sommerfeld

1996-01-01

A study of the water chemistry of Colorado Rocky Mountain Front Range alpine/subalpine lakes and streams in wilderness ecosystems was conducted during the summer of 1995 by the USDA Forest Service Arapaho and Roosevelt National Forests and Rocky Mountain Forest and Range Experiment Station, and the University of Colorado Institute of Alpine and Arctic Research. Data...

Predicting regeneration in the grand fir-cedar-hemlock ecosystem of the northern Rocky Mountains

Treesearch

Dennis E. Ferguson; Albert R. Stage; Raymond J. Boyd

1986-01-01

Conifer establishment following regeneration treatments can be predicted in the grand fir-cedar-hemlock ecosystem of the northern Rocky Mountains. Alternative treatments can be evaluated by a model that represents regeneration establishment and early development. This model is designed to be used with the Intermountain Forest and Range Experiment Station's...

The experimental design of the Missouri Ozark Forest Ecosystem Project

Treesearch

Steven L. Sheriff; Shuoqiong He

1997-01-01

The Missouri Ozark Forest Ecosystem Project (MOFEP) is an experiment that examines the effects of three forest management practices on the forest community. MOFEP is designed as a randomized complete block design using nine sites divided into three blocks. Treatments of uneven-aged, even-aged, and no-harvest management were randomly assigned to sites within each block...

Quantifying effects of biodiversity on ecosystem functioning across times and places†

PubMed Central

Isbell, Forest; Cowles, Jane; Dee, Laura E.; Loreau, Michel; Reich, Peter B.; Gonzalez, Andrew; Hector, Andy; Schmid, Bernhard

2018-01-01

Biodiversity loss decreases ecosystem functioning at the local scales at which species interact, but it remains unclear how biodiversity loss affects ecosystem functioning at the larger scales of space and time that are most relevant to biodiversity conservation and policy. Theory predicts that additional insurance effects of biodiversity on ecosystem functioning could emerge across time and space if species respond asynchronously to environmental variation and if species become increasingly dominant when and where they are most productive. Even if only a few dominant species maintain ecosystem functioning within a particular time and place, ecosystem functioning may be enhanced by many different species across many times and places (β-diversity). Here, we develop and apply a new approach to estimate these previously unquantified insurance effects of biodiversity on ecosystem functioning that arise due to species turnover across times and places. In a long-term (18-year) grassland plant diversity experiment, we find that total insurance effects are positive in sign and substantial in magnitude, amounting to 19% of the net biodiversity effect, mostly due to temporal insurance effects. Species loss can therefore reduce ecosystem functioning both locally and by eliminating species that would otherwise enhance ecosystem functioning across temporally fluctuating and spatially heterogeneous environments. PMID:29493062

Changes in the location of biodiversity-ecosystem function hot spots across the seafloor landscape with increasing sediment nutrient loading.

PubMed

Thrush, Simon F; Hewitt, Judi E; Kraan, Casper; Lohrer, A M; Pilditch, Conrad A; Douglas, Emily

2017-04-12

Declining biodiversity and loss of ecosystem function threatens the ability of habitats to contribute ecosystem services. However, the form of the relationship between biodiversity and ecosystem function (BEF) and how relationships change with environmental change is poorly understood. This limits our ability to predict the consequences of biodiversity loss on ecosystem function, particularly in real-world marine ecosystems that are species rich, and where multiple ecosystem functions are represented by multiple indicators. We investigated spatial variation in BEF relationships across a 300 000 m 2 intertidal sandflat by nesting experimental manipulations of sediment pore water nitrogen concentration into sites with contrasting macrobenthic community composition. Our results highlight the significance of many different elements of biodiversity associated with environmental characteristics, community structure, functional diversity, ecological traits or particular species (ecosystem engineers) to important functions of coastal marine sediments (benthic oxygen consumption, ammonium pore water concentrations and flux across the sediment-water interface). Using the BEF relationships developed from our experiment, we demonstrate patchiness across a landscape in functional performance and the potential for changes in the location of functional hot and cold spots with increasing nutrient loading that have important implications for mapping and predicating change in functionality and the concomitant delivery of ecosystem services. © 2017 The Author(s).

Quantifying effects of biodiversity on ecosystem functioning across times and places.

PubMed

Isbell, Forest; Cowles, Jane; Dee, Laura E; Loreau, Michel; Reich, Peter B; Gonzalez, Andrew; Hector, Andy; Schmid, Bernhard

2018-06-01

Biodiversity loss decreases ecosystem functioning at the local scales at which species interact, but it remains unclear how biodiversity loss affects ecosystem functioning at the larger scales of space and time that are most relevant to biodiversity conservation and policy. Theory predicts that additional insurance effects of biodiversity on ecosystem functioning could emerge across time and space if species respond asynchronously to environmental variation and if species become increasingly dominant when and where they are most productive. Even if only a few dominant species maintain ecosystem functioning within a particular time and place, ecosystem functioning may be enhanced by many different species across many times and places (β-diversity). Here, we develop and apply a new approach to estimate these previously unquantified insurance effects of biodiversity on ecosystem functioning that arise due to species turnover across times and places. In a long-term (18-year) grassland plant diversity experiment, we find that total insurance effects are positive in sign and substantial in magnitude, amounting to 19% of the net biodiversity effect, mostly due to temporal insurance effects. Species loss can therefore reduce ecosystem functioning both locally and by eliminating species that would otherwise enhance ecosystem functioning across temporally fluctuating and spatially heterogeneous environments. © 2018 John Wiley & Sons Ltd/CNRS.

Complex carbon cycle responses to multi-level warming and supplemental summer rain in the high Arctic.

PubMed

Sharp, Elizabeth D; Sullivan, Patrick F; Steltzer, Heidi; Csank, Adam Z; Welker, Jeffrey M

2013-06-01

The Arctic has experienced rapid warming and, although there are uncertainties, increases in precipitation are projected to accompany future warming. Climate changes are expected to affect magnitudes of gross ecosystem photosynthesis (GEP), ecosystem respiration (ER) and the net ecosystem exchange of CO2 (NEE). Furthermore, ecosystem responses to climate change are likely to be characterized by nonlinearities, thresholds and interactions among system components and the driving variables. These complex interactions increase the difficulty of predicting responses to climate change and necessitate the use of manipulative experiments. In 2003, we established a long-term, multi-level and multi-factor climate change experiment in a polar semidesert in northwest Greenland. Two levels of heating (30 and 60 W m(-2) ) were applied and the higher level was combined with supplemental summer rain. We made plot-level measurements of CO2 exchange, plant community composition, foliar nitrogen concentrations, leaf δ(13) C and NDVI to examine responses to our treatments at ecosystem- and leaf-levels. We confronted simple models of GEP and ER with our data to test hypotheses regarding key drivers of CO2 exchange and to estimate growing season CO2 -C budgets. Low-level warming increased the magnitude of the ecosystem C sink. Meanwhile, high-level warming made the ecosystem a source of C to the atmosphere. When high-level warming was combined with increased summer rain, the ecosystem became a C sink of magnitude similar to that observed under low-level warming. Competition among our ER models revealed the importance of soil moisture as a driving variable, likely through its effects on microbial activity and nutrient cycling. Measurements of community composition and proxies for leaf-level physiology suggest GEP responses largely reflect changes in leaf area of Salix arctica, rather than changes in leaf-level physiology. Our findings indicate that the sign and magnitude of the future High Arctic C budget may depend upon changes in summer rain. © 2013 Blackwell Publishing Ltd.

Uncovering stability mechanisms in microbial ecosystems - combining microcosm experiments, computational modelling and ecological theory in a multidisciplinary approach

NASA Astrophysics Data System (ADS)

Worrich, Anja; König, Sara; Banitz, Thomas; Centler, Florian; Frank, Karin; Kästner, Matthias; Miltner, Anja; Thullner, Martin; Wick, Lukas

2015-04-01

Although bacterial degraders in soil are commonly exposed to fluctuating environmental conditions, the functional performance of the biodegradation processes can often be maintained by resistance and resilience mechanisms. However, there is still a gap in the mechanistic understanding of key factors contributing to the stability of such an ecosystem service. Therefore we developed an integrated approach combining microcosm experiments, simulation models and ecological theory to directly make use of the strengths of these disciplines. In a continuous interplay process, data, hypotheses, and central questions are exchanged between disciplines to initiate new experiments and models to ultimately identify buffer mechanisms and factors providing functional stability. We focus on drying and rewetting-cycles in soil ecosystems, which are a major abiotic driver for bacterial activity. Functional recovery of the system was found to depend on different spatial processes in the computational model. In particular, bacterial motility is a prerequisite for biodegradation if either bacteria or substrate are heterogeneously distributed. Hence, laboratory experiments focussing on bacterial dispersal processes were conducted and confirmed this finding also for functional resistance. Obtained results will be incorporated into the model in the next step. Overall, the combination of computational modelling and laboratory experiments identified spatial processes as the main driving force for functional stability in the considered system, and has proved a powerful methodological approach.

Hydrologically driven ecosystem processes determine the distribution and persistence of ecosystem-specialist predators under climate change.

PubMed

Carroll, Matthew J; Heinemeyer, Andreas; Pearce-Higgins, James W; Dennis, Peter; West, Chris; Holden, Joseph; Wallage, Zoe E; Thomas, Chris D

2015-07-31

Climate change has the capacity to alter physical and biological ecosystem processes, jeopardizing the survival of associated species. This is a particular concern in cool, wet northern peatlands that could experience warmer, drier conditions. Here we show that climate, ecosystem processes and food chains combine to influence the population performance of species in British blanket bogs. Our peatland process model accurately predicts water-table depth, which predicts abundance of craneflies (keystone invertebrates), which in turn predicts observed abundances and population persistence of three ecosystem-specialist bird species that feed on craneflies during the breeding season. Climate change projections suggest that falling water tables could cause 56-81% declines in cranefly abundance and, hence, 15-51% reductions in the abundances of these birds by 2051-2080. We conclude that physical (precipitation, temperature and topography), biophysical (evapotranspiration and desiccation of invertebrates) and ecological (food chains) processes combine to determine the distributions and survival of ecosystem-specialist predators.

Hydrologically driven ecosystem processes determine the distribution and persistence of ecosystem-specialist predators under climate change

PubMed Central

Carroll, Matthew J.; Heinemeyer, Andreas; Pearce-Higgins, James W.; Dennis, Peter; West, Chris; Holden, Joseph; Wallage, Zoe E.; Thomas, Chris D.

2015-01-01

Climate change has the capacity to alter physical and biological ecosystem processes, jeopardizing the survival of associated species. This is a particular concern in cool, wet northern peatlands that could experience warmer, drier conditions. Here we show that climate, ecosystem processes and food chains combine to influence the population performance of species in British blanket bogs. Our peatland process model accurately predicts water-table depth, which predicts abundance of craneflies (keystone invertebrates), which in turn predicts observed abundances and population persistence of three ecosystem-specialist bird species that feed on craneflies during the breeding season. Climate change projections suggest that falling water tables could cause 56–81% declines in cranefly abundance and, hence, 15–51% reductions in the abundances of these birds by 2051–2080. We conclude that physical (precipitation, temperature and topography), biophysical (evapotranspiration and desiccation of invertebrates) and ecological (food chains) processes combine to determine the distributions and survival of ecosystem-specialist predators. PMID:26227623

Response of NDVI, biomass, and ecosystem gas exchange to long-term warming and fertilization in wet sedge tundra.

PubMed

Boelman, Natalie T; Stieglitz, Marc; Rueth, Heather M; Sommerkorn, Martin; Griffin, Kevin L; Shaver, Gaius R; Gamon, John A

2003-05-01

This study explores the relationship between the normalized difference vegetation index (NDVI), aboveground plant biomass, and ecosystem C fluxes including gross ecosystem production (GEP), ecosystem respiration (ER) and net ecosystem production. We measured NDVI across long-term experimental treatments in wet sedge tundra at the Toolik Lake LTER site, in northern Alaska. Over 13 years, N and P were applied in factorial experiments (N, P and N + P), air temperature was increased using greenhouses with and without N + P fertilizer, and light intensity (photosynthetically active photon flux density) was reduced by 50% using shade cloth. Within each treatment plot, NDVI, aboveground biomass and whole-system CO(2) flux measurements were made at the same sampling points during the peak-growing season of 2001. We found that across all treatments, NDVI is correlated with aboveground biomass ( r(2)=0.84), GEP ( r(2)=0.75) and ER ( r(2)=0.71), providing a basis for linking remotely sensed NDVI to aboveground biomass and ecosystem carbon flux.

Biodiversity increases the resistance of ecosystem productivity to climate extremes

NASA Astrophysics Data System (ADS)

Isbell, Forest; Craven, Dylan; Connolly, John; Loreau, Michel; Schmid, Bernhard; Beierkuhnlein, Carl; Bezemer, T. Martijn; Bonin, Catherine; Bruelheide, Helge; de Luca, Enrica; Ebeling, Anne; Griffin, John N.; Guo, Qinfeng; Hautier, Yann; Hector, Andy; Jentsch, Anke; Kreyling, Jürgen; Lanta, Vojtěch; Manning, Pete; Meyer, Sebastian T.; Mori, Akira S.; Naeem, Shahid; Niklaus, Pascal A.; Polley, H. Wayne; Reich, Peter B.; Roscher, Christiane; Seabloom, Eric W.; Smith, Melinda D.; Thakur, Madhav P.; Tilman, David; Tracy, Benjamin F.; van der Putten, Wim H.; van Ruijven, Jasper; Weigelt, Alexandra; Weisser, Wolfgang W.; Wilsey, Brian; Eisenhauer, Nico

2015-10-01

It remains unclear whether biodiversity buffers ecosystems against climate extremes, which are becoming increasingly frequent worldwide. Early results suggested that the ecosystem productivity of diverse grassland plant communities was more resistant, changing less during drought, and more resilient, recovering more quickly after drought, than that of depauperate communities. However, subsequent experimental tests produced mixed results. Here we use data from 46 experiments that manipulated grassland plant diversity to test whether biodiversity provides resistance during and resilience after climate events. We show that biodiversity increased ecosystem resistance for a broad range of climate events, including wet or dry, moderate or extreme, and brief or prolonged events. Across all studies and climate events, the productivity of low-diversity communities with one or two species changed by approximately 50% during climate events, whereas that of high-diversity communities with 16-32 species was more resistant, changing by only approximately 25%. By a year after each climate event, ecosystem productivity had often fully recovered, or overshot, normal levels of productivity in both high- and low-diversity communities, leading to no detectable dependence of ecosystem resilience on biodiversity. Our results suggest that biodiversity mainly stabilizes ecosystem productivity, and productivity-dependent ecosystem services, by increasing resistance to climate events. Anthropogenic environmental changes that drive biodiversity loss thus seem likely to decrease ecosystem stability, and restoration of biodiversity to increase it, mainly by changing the resistance of ecosystem productivity to climate events.

Biodiversity increases the resistance of ecosystem productivity to climate extremes.

PubMed

Isbell, Forest; Craven, Dylan; Connolly, John; Loreau, Michel; Schmid, Bernhard; Beierkuhnlein, Carl; Bezemer, T Martijn; Bonin, Catherine; Bruelheide, Helge; de Luca, Enrica; Ebeling, Anne; Griffin, John N; Guo, Qinfeng; Hautier, Yann; Hector, Andy; Jentsch, Anke; Kreyling, Jürgen; Lanta, Vojtěch; Manning, Pete; Meyer, Sebastian T; Mori, Akira S; Naeem, Shahid; Niklaus, Pascal A; Polley, H Wayne; Reich, Peter B; Roscher, Christiane; Seabloom, Eric W; Smith, Melinda D; Thakur, Madhav P; Tilman, David; Tracy, Benjamin F; van der Putten, Wim H; van Ruijven, Jasper; Weigelt, Alexandra; Weisser, Wolfgang W; Wilsey, Brian; Eisenhauer, Nico

2015-10-22

It remains unclear whether biodiversity buffers ecosystems against climate extremes, which are becoming increasingly frequent worldwide. Early results suggested that the ecosystem productivity of diverse grassland plant communities was more resistant, changing less during drought, and more resilient, recovering more quickly after drought, than that of depauperate communities. However, subsequent experimental tests produced mixed results. Here we use data from 46 experiments that manipulated grassland plant diversity to test whether biodiversity provides resistance during and resilience after climate events. We show that biodiversity increased ecosystem resistance for a broad range of climate events, including wet or dry, moderate or extreme, and brief or prolonged events. Across all studies and climate events, the productivity of low-diversity communities with one or two species changed by approximately 50% during climate events, whereas that of high-diversity communities with 16-32 species was more resistant, changing by only approximately 25%. By a year after each climate event, ecosystem productivity had often fully recovered, or overshot, normal levels of productivity in both high- and low-diversity communities, leading to no detectable dependence of ecosystem resilience on biodiversity. Our results suggest that biodiversity mainly stabilizes ecosystem productivity, and productivity-dependent ecosystem services, by increasing resistance to climate events. Anthropogenic environmental changes that drive biodiversity loss thus seem likely to decrease ecosystem stability, and restoration of biodiversity to increase it, mainly by changing the resistance of ecosystem productivity to climate events.

Experimental evidence that parasites drive eco-evolutionary feedbacks.

PubMed

Brunner, Franziska S; Anaya-Rojas, Jaime M; Matthews, Blake; Eizaguirre, Christophe

2017-04-04

Host resistance to parasites is a rapidly evolving trait that can influence how hosts modify ecosystems. Eco-evolutionary feedbacks may develop if the ecosystem effects of host resistance influence selection on subsequent host generations. In a mesocosm experiment, using a recently diverged (<100 generations) pair of lake and stream three-spined sticklebacks, we tested how experimental exposure to a common fish parasite ( Gyrodactylus spp.) affects interactions between hosts and their ecosystems in two environmental conditions (low and high nutrients). In both environments, we found that stream sticklebacks were more resistant to Gyrodactylus and had different gene expression profiles than lake sticklebacks. This differential infection led to contrasting effects of sticklebacks on a broad range of ecosystem properties, including zooplankton community structure and nutrient cycling. These ecosystem modifications affected the survival, body condition, and gene expression profiles of a subsequent fish generation. In particular, lake juvenile fish suffered increased mortality in ecosystems previously modified by lake adults, whereas stream fish showed decreased body condition in stream fish-modified ecosystems. Parasites reinforced selection against lake juveniles in lake fish-modified ecosystems, but only under oligotrophic conditions. Overall, our results highlight the overlapping timescales and the interplay of host-parasite and host-ecosystem interactions. We provide experimental evidence that parasites influence host-mediated effects on ecosystems and, thereby, change the likelihood and strength of eco-evolutionary feedbacks.

Experimental evidence that parasites drive eco-evolutionary feedbacks

PubMed Central

Brunner, Franziska S.; Anaya-Rojas, Jaime M.; Matthews, Blake; Eizaguirre, Christophe

2017-01-01

Host resistance to parasites is a rapidly evolving trait that can influence how hosts modify ecosystems. Eco-evolutionary feedbacks may develop if the ecosystem effects of host resistance influence selection on subsequent host generations. In a mesocosm experiment, using a recently diverged (<100 generations) pair of lake and stream three-spined sticklebacks, we tested how experimental exposure to a common fish parasite (Gyrodactylus spp.) affects interactions between hosts and their ecosystems in two environmental conditions (low and high nutrients). In both environments, we found that stream sticklebacks were more resistant to Gyrodactylus and had different gene expression profiles than lake sticklebacks. This differential infection led to contrasting effects of sticklebacks on a broad range of ecosystem properties, including zooplankton community structure and nutrient cycling. These ecosystem modifications affected the survival, body condition, and gene expression profiles of a subsequent fish generation. In particular, lake juvenile fish suffered increased mortality in ecosystems previously modified by lake adults, whereas stream fish showed decreased body condition in stream fish-modified ecosystems. Parasites reinforced selection against lake juveniles in lake fish-modified ecosystems, but only under oligotrophic conditions. Overall, our results highlight the overlapping timescales and the interplay of host–parasite and host–ecosystem interactions. We provide experimental evidence that parasites influence host-mediated effects on ecosystems and, thereby, change the likelihood and strength of eco-evolutionary feedbacks. PMID:28320947

Bayesian analysis of non-linear differential equation models with application to a gut microbial ecosystem.

PubMed

Lawson, Daniel J; Holtrop, Grietje; Flint, Harry

2011-07-01

Process models specified by non-linear dynamic differential equations contain many parameters, which often must be inferred from a limited amount of data. We discuss a hierarchical Bayesian approach combining data from multiple related experiments in a meaningful way, which permits more powerful inference than treating each experiment as independent. The approach is illustrated with a simulation study and example data from experiments replicating the aspects of the human gut microbial ecosystem. A predictive model is obtained that contains prediction uncertainty caused by uncertainty in the parameters, and we extend the model to capture situations of interest that cannot easily be studied experimentally. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Changes in ecosystem resilience detected in automated measures of ecosystem metabolism during a whole-lake manipulation

PubMed Central

Batt, Ryan D.; Carpenter, Stephen R.; Cole, Jonathan J.; Pace, Michael L.; Johnson, Robert A.

2013-01-01

Environmental sensor networks are developing rapidly to assess changes in ecosystems and their services. Some ecosystem changes involve thresholds, and theory suggests that statistical indicators of changing resilience can be detected near thresholds. We examined the capacity of environmental sensors to assess resilience during an experimentally induced transition in a whole-lake manipulation. A trophic cascade was induced in a planktivore-dominated lake by slowly adding piscivorous bass, whereas a nearby bass-dominated lake remained unmanipulated and served as a reference ecosystem during the 4-y experiment. In both the manipulated and reference lakes, automated sensors were used to measure variables related to ecosystem metabolism (dissolved oxygen, pH, and chlorophyll-a concentration) and to estimate gross primary production, respiration, and net ecosystem production. Thresholds were detected in some automated measurements more than a year before the completion of the transition to piscivore dominance. Directly measured variables (dissolved oxygen, pH, and chlorophyll-a concentration) related to ecosystem metabolism were better indicators of the approaching threshold than were the estimates of rates (gross primary production, respiration, and net ecosystem production); this difference was likely a result of the larger uncertainties in the derived rate estimates. Thus, relatively simple characteristics of ecosystems that were observed directly by the sensors were superior indicators of changing resilience. Models linked to thresholds in variables that are directly observed by sensor networks may provide unique opportunities for evaluating resilience in complex ecosystems. PMID:24101479

Changes in ecosystem resilience detected in automated measures of ecosystem metabolism during a whole-lake manipulation.

PubMed

Batt, Ryan D; Carpenter, Stephen R; Cole, Jonathan J; Pace, Michael L; Johnson, Robert A

2013-10-22

Environmental sensor networks are developing rapidly to assess changes in ecosystems and their services. Some ecosystem changes involve thresholds, and theory suggests that statistical indicators of changing resilience can be detected near thresholds. We examined the capacity of environmental sensors to assess resilience during an experimentally induced transition in a whole-lake manipulation. A trophic cascade was induced in a planktivore-dominated lake by slowly adding piscivorous bass, whereas a nearby bass-dominated lake remained unmanipulated and served as a reference ecosystem during the 4-y experiment. In both the manipulated and reference lakes, automated sensors were used to measure variables related to ecosystem metabolism (dissolved oxygen, pH, and chlorophyll-a concentration) and to estimate gross primary production, respiration, and net ecosystem production. Thresholds were detected in some automated measurements more than a year before the completion of the transition to piscivore dominance. Directly measured variables (dissolved oxygen, pH, and chlorophyll-a concentration) related to ecosystem metabolism were better indicators of the approaching threshold than were the estimates of rates (gross primary production, respiration, and net ecosystem production); this difference was likely a result of the larger uncertainties in the derived rate estimates. Thus, relatively simple characteristics of ecosystems that were observed directly by the sensors were superior indicators of changing resilience. Models linked to thresholds in variables that are directly observed by sensor networks may provide unique opportunities for evaluating resilience in complex ecosystems.

Nutrient Budgets Calculated in Floodwaters Using a Whole-Ecosystem Experimental Manipulation

NASA Astrophysics Data System (ADS)

Talbot, C. J.; Paterson, M. J.; Xenopoulos, M. A.

2017-12-01

Flooding provides pathways for nutrients to move into surface waters and alter nutrient concentrations, therefore influencing downstream ecosystems and increasing events of eutrophication. Nutrient enrichment will likely affect water quality, primary production, and overall ecosystem function. Quantifying nutrient movement post-flood will help evaluate the risks or advantages that flooding will have on ecosystem processes. Here we constructed nutrient budgets using data collected as part of the Flooded Upland Dynamics Experiment (FLUDEX) at the Experimental Lakes Area (ELA) in northwestern Ontario. Three experimental reservoirs with varying amounts of stored carbon were created by flooding forested land from May through September annually from 1999 to 2003. Organic matter became a significant source of nutrients under flooded conditions and elevated reservoir total nitrogen (TN) and total phosphorus (TP) concentrations within one week of flooding. The highest TN (2.6 mg L-1) and TP (579 µg L-1) concentrations throughout the entire flooding experiment occurred in the medium carbon reservoir within the first two weeks of flooding in 1999. TN and TP fluxes were positive in all years of flooding. TP fluxes decreased after each flooding season therefore, TP production may be less problematic in floodplains subject to frequent repeated flooding. However, TN fluxes remained large even after repeated flooding. Therefore, flooding, whether naturally occurring or from anthropogenic flow alteration, may be responsible for producing significant amounts of nitrogen and phosphorus in aquatic ecosystems.

Challenges for Complex Microbial Ecosystems: Combination of Experimental Approaches with Mathematical Modeling

PubMed Central

Haruta, Shin; Yoshida, Takehito; Aoi, Yoshiteru; Kaneko, Kunihiko; Futamata, Hiroyuki

2013-01-01

In the past couple of decades, molecular ecological techniques have been developed to elucidate microbial diversity and distribution in microbial ecosystems. Currently, modern techniques, represented by meta-omics and single cell observations, are revealing the incredible complexity of microbial ecosystems and the large degree of phenotypic variation. These studies propound that microbiological techniques are insufficient to untangle the complex microbial network. This minireview introduces the application of advanced mathematical approaches in combination with microbiological experiments to microbial ecological studies. These combinational approaches have successfully elucidated novel microbial behaviors that had not been recognized previously. Furthermore, the theoretical perspective also provides an understanding of the plasticity, robustness and stability of complex microbial ecosystems in nature. PMID:23995424

A comprehensive data acquisition and management system for an ecosystem-scale peatland warming and elevated CO 2 experiment

DOE PAGES

Krassovski, M. B.; Riggs, J. S.; Hook, L. A.; ...

2015-11-09

Ecosystem-scale manipulation experiments represent large science investments that require well-designed data acquisition and management systems to provide reliable, accurate information to project participants and third party users. The SPRUCE project (Spruce and Peatland Responses Under Climatic and Environmental Change, http://mnspruce.ornl.gov) is such an experiment funded by the Department of Energy's (DOE), Office of Science, Terrestrial Ecosystem Science (TES) Program. The SPRUCE experimental mission is to assess ecosystem-level biological responses of vulnerable, high carbon terrestrial ecosystems to a range of climate warming manipulations and an elevated CO 2 atmosphere. SPRUCE provides a platform for testing mechanisms controlling the vulnerability of organisms,more » biogeochemical processes, and ecosystems to climatic change (e.g., thresholds for organism decline or mortality, limitations to regeneration, biogeochemical limitations to productivity, and the cycling and release of CO 2 and CH 4 to the atmosphere). The SPRUCE experiment will generate a wide range of continuous and discrete measurements. In order to successfully manage SPRUCE data collection, achieve SPRUCE science objectives, and support broader climate change research, the research staff has designed a flexible data system using proven network technologies and software components. The primary SPRUCE data system components are the following; 1. data acquisition and control system – set of hardware and software to retrieve biological and engineering data from sensors, collect sensor status information, and distribute feedback to control components; 2. data collection system – set of hardware and software to deliver data to a central depository for storage and further processing; and 3. data management plan – set of plans, policies, and practices to control consistency, protect data integrity, and deliver data. This publication presents our approach to meeting the challenges of designing and constructing an efficient data system for managing high volume sources of in situ observations in a remote, harsh environmental location. Finally, the approach covers data flow starting from the sensors and ending at the archival/distribution points, discusses types of hardware and software used, examines design considerations that were used to choose them, and describes the data management practices chosen to control and enhance the value of the data.« less

Natural enemies govern ecosystem resilience in the face of extreme droughts.

PubMed

He, Qiang; Silliman, Brian R; Liu, Zezheng; Cui, Baoshan

2017-02-01

Severe droughts are on the rise in many regions. But thus far, attempts to predict when drought will cause a major regime shift or when ecosystems are resilient, often using plant drought tolerance models, have been frustrated. Here, we show that pressure from natural enemies regulates an ecosystem's resilience to severe droughts. Field experiments revealed that in protected salt marshes experiencing a severe drought, plant-eating grazers eliminated drought-stressed vegetation that could otherwise survive and recover from the climate extreme, transforming once lush marshes into persistent salt barrens. These results provide an explicit experimental demonstration for the obligatory role of natural enemies across the initiation, expansion and recovery stages of a natural ecosystem's collapse. Our study highlights that natural enemies can hasten an ecosystem's resilience to drought to much lower levels than currently predicted, calling for integration into climate change predictions and conservation strategies. © 2017 John Wiley & Sons Ltd/CNRS.

High Resolution Mapping of Wetland Ecosystems SPOT-5 Take 5 for Evaluation of Sentinel-2

NASA Astrophysics Data System (ADS)

Ade, Christiana; Hestir, Erin L.; Khanna, Shruti; Ustin, Susan L.

2016-08-01

Around the world wetlands are critical to human societies and ecosystems, providing services such as habitat, water, food and fiber, flood and nutrient control, and cultural, recreational and religious value. However, the dynamic nature of tidal wetlands makes measuring ecosystem responses to climate change, seasonal inundation regimes, and anthropogenic disturbance from current and previous Earth observing sensors challenging due to limited spatial and temporal resolutions. Sentinel- 2 will directly address this challenge by providing high spatial resolution data with frequent revisit time. This pilot study aims to develop methodology for future Sentinel-2 products and highlight the variability of tidal wetland ecosystems, thereby demonstrating the necessity of improved spatial particularly temporal resolution. Here the simulated Sentinel-2 dataset from the SPOT-5 Take 5 experiment reveals the capacity of the new sensor to simultaneously assess tidal wetland ecosystem phenology and water quality in inland waters.

Effects of biodiversity on ecosystem functioning: a consensus of current knowledge

USGS Publications Warehouse

Hooper, D.U.; Chapin, F. S.; Ewel, J.J.; Hector, A.; Inchausti, P.; Lavorel, S.; Lawton, J.H.; Lodge, D.M.; Loreau, M.; Naeem, S.; Schmid, B.; SetSlS, H.; Symstad, A.J.; Vandermeer, J.; Wardle, D.A.

2005-01-01

Humans are altering the composition of biological communities through a variety of activities that increase rates of species invasions and species extinctions, at all scales, from local to global. These changes in components of the Earth's biodiversity cause concern for ethical and aesthetic reasons, but they also have a strong potential to alter ecosystem properties and the goods and services they provide to humanity. Ecological experiments, observations, and theoretical developments show that ecosystem properties depend greatly on biodiversity in terms of the functional characteristics of organisms present in the ecosystem and the distribution and abundance of those organisms over space and time. Species effects act in concert with the effects of climate, resource availability, and disturbance regimes in influencing ecosystem properties. Human activities can modify all of the above factors; here we focus on modification of these biotic controls.The scientific community has come to a broad consensus on many aspects of the relationship between biodiversity and ecosystem functioning, including many points relevant to management of ecosystems. Further progress will require integration of knowledge about biotic and abiotic controls on ecosystem properties, how ecological communities are structured, and the forces driving species extinctions and invasions. To strengthen links to policy and management, we also need to integrate our ecological knowledge with understanding of the social and economic constraints of potential management practices. Understanding this complexity, while taking strong steps to minimize current losses of species, is necessary for responsible management of Earth's ecosystems and the diverse biota they contain.Based on our review of the scientific literature, we are certain of the following conclusions:1) Species' functional characteristics strongly influence ecosystem properties. Functional characteristics operate in a variety of contexts, including effects of dominant species, keystone species, ecological engineers, and interactions among species (e.g., competition, facilitation, mutualism, disease, and predation). Relative abundance alone is not always a good predictor of the ecosystem-level importance of a species, as even relatively rare species (e.g., a keystone predator) can strongly influence pathways of energy and material flows.2) Alteration of biota in ecosystems via species invasions and extinctions caused by human activities has altered ecosystem goods and services in many well-documented cases. Many of these changes are difficult, expensive, or impossible to reverse or fix with technological solutions.3) The effects of species loss or changes in composition, and the mechanisms by which the effects manifest themselves, can differ among ecosystem properties, ecosystem types, and pathways of potential community change.4) Some ecosystem properties are initially insensitive to species loss because (a) ecosystems may have multiple species that carry out similar functional roles, (b) some species may contribute relatively little to ecosystem properties, or (c) properties may be primarily controlled by abiotic environmental conditions.5) More species are needed to insure a stable supply of ecosystem goods and services as spatial and temporal variability increases, which typically occurs as longer time periods and larger areas are considered.We have high confidence in the following conclusions:1) Certain combinations of species are complementary in their patterns of resource use and can increase average rates of productivity and nutrient retention. At the same time, environmental conditions can influence the importance of complementarity in structuring communities. Identification of which and how many species act in a complementary way in complex communities is just beginning.2) Susceptibility to invasion by exotic species is strongly influenced by species composition and, under similar environmental conditions, generally decreases with increasing species richness. However, several other factors, such as propagule pressure, disturbance regime, and resource availability also strongly influence invasion success and often override effects of species richness in comparisons across different sites or ecosystems.3) Having a range of species that respond differently to different environmental perturbations can stabilize ecosystem process rates in response to disturbances and variation in abiotic conditions. Using practices that maintain a diversity of organisms of different functional effect and functional response types will help preserve a range of management options.Uncertainties remain and further research is necessary in the following areas:1) Further resolution of the relationships among taxonomic diversity, functional diversity, and community structure is important for identifying mechanisms of biodiversity effects.2) Multiple trophic levels are common to ecosystems but have been understudied in biodiversity/ecosystem functioning research. The response of ecosystem properties to varying composition and diversity of consumer organisms is much more complex than responses seen in experiments that vary only the diversity of primary producers.3) Theoretical work on stability has outpaced experimental work, especially field research. We need long-term experiments to be able to assess temporal stability, as well as experimental perturbations to assess response to and recovery from a variety of disturbances. Design and analysis of such experiments must account for several factors that covary with species diversity.4) Because biodiversity both responds to and influences ecosystem properties, understanding the feedbacks involved is necessary to integrate results from experimental communities with patterns seen at broader scales. Likely patterns of extinction and invasion need to be linked to different drivers of global change, the forces that structure communities, and controls on ecosystem properties for the development of effective management and conservation strategies.5) This paper focuses primarily on terrestrial systems, with some coverage of freshwater systems, because that is where most empirical and theoretical study has focused. While the fundamental principles described here should apply to marine systems, further study of that realm is necessary.Despite some uncertainties about the mechanisms and circumstances under which diversity influences ecosystem properties, incorporating diversity effects into policy and management is essential, especially in making decisions involving large temporal and spatial scales. Sacrificing those aspects of ecosystems that are difficult or impossible to reconstruct, such as diversity, simply because we are not yet certain about the extent and mechanisms by which they affect ecosystem properties, will restrict future management options even further. It is incumbent upon ecologists to communicate this need, and the values that can derive from such a perspective, to those charged with economic and policy decision-making.

The Moquah Barrens Research Natural Area: Loss of a pine barrens ecosystem

Treesearch

Christine A. Ribic; David J. Rugg; Deahn M. Donner; Albert J. Beck; BJ. Byers

2016-01-01

The Moquah Barrens Research Natural Area (RNA) was established by the Chequamegon National Forest and the Lakes States Forest Experiment Station in 1935 with a research objective well-suited to the needs of the Forest Service and the scientific understanding of ecosystem function prevalent at the time of establishment. The original research plan was never implemented,...

A new way to study the changing Arctic ecosystem

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hubbard, Susan

2011-09-12

Berkeley Lab scientists Susan Hubbard and Margaret Torn discuss the proposed Next Generation Ecosystem Experiment, which is designed to answer one of the most urgent questions facing researchers today: How will a changing climate impact the Arctic, and how will this in turn impact the planet's climate? More info: http://newscenter.lbl.gov/feature-stories/2011/09/14/alaska-climate-change/

A new way to study the changing Arctic ecosystem

ScienceCinema

Hubbard, Susan

2017-12-09

Berkeley Lab scientists Susan Hubbard and Margaret Torn discuss the proposed Next Generation Ecosystem Experiment, which is designed to answer one of the most urgent questions facing researchers today: How will a changing climate impact the Arctic, and how will this in turn impact the planet's climate? More info: http://newscenter.lbl.gov/feature-stories/2011/09/14/alaska-climate-change/

Across the City and across Grades: Investigating Energy Flow in the Boston Harbor Ecosystem

ERIC Educational Resources Information Center

Hashimoto-Martell, Erin; Clinchot, Michael; Daniels, Haven; Bennie, Fiona

2012-01-01

In the project described in this article, urban students from across grade levels, schools, and abilities were brought together by four science teachers to better understand an ecosystem of their local environment, the Boston Harbor. This project comprises two main field experiences to the Boston Harbor: the first one to a nearby beach, and the…

Pre-treatment analysis of woody vegetation composition and structure on the hardwood ecosystem experiment research units

Treesearch

Michael R. Saunders; Justin E. Arseneault

2013-01-01

In long-term, large-scale forest management studies, documentation of pre-treatment differences among and variability within experimental units is critical for drawing the proper inferences from imposed treatments. We compared pre-treatment overstory and large shrub communities (diameters at breast height >1.5 cm) for the 9 research cores with the Hardwood Ecosystem...

Ecosystem Reversals of Fortune in Response to Long-Term Experimental N Deposition.

NASA Astrophysics Data System (ADS)

Vourlitis, G. L.

2017-12-01

Anthropogenic nitrogen (N) deposition has the capacity to alter terrestrial ecosystem structure and function; however, short-term (months-years) responses may be fundamentally different than long-term (years-decades) responses. Here the results of a 14 year field N addition experiment are reported for two different Southern Californian semi-arid shrublands, a post-fire chaparral and a mature coastal sage scrub (CSS), that have been exposed to 50 kgN ha-1 yr-1 since 2003. Since >90% of the anthropogenic N in this region consists of dry deposition, N was added during the late-summer or early-fall each year to assess how dry N inputs alter ecosystem processes. Both shrublands experienced complete reversals in their response to experimental N input. For example, post-fire chaparral plots exposed to added N had significantly lower net primary production (NPP) than control plots over the first 3 years of the experiment, but thereafter, the NPP in N plots increased consistently each year and became significantly higher than in control plots after 7 years of N fertilization. In CSS, NPP and the abundance of Artemisia californica, a co-dominant shrub, increased significantly in N plots over the first 6 years, but thereafter, NPP and the abundance of A. californica and Salvia mellifera, the other co-dominant shrub, declined. Now the N plots have a lower NPP and are dominated by the invasive annual Brassica nigra. These transient responses, and interactions between N accumulation and other factors such as post-fire succession (chaparral) and chronic drought (CSS), would have been missed if the experiment was ended after the end of a typical funding cycle, and highlighting the importance of long-duration field experiments in assessing ecosystem responses to chronic N enrichment.

Non-use Economic Values for Little-Known Aquatic Species at Risk: Comparing Choice Experiment Results from Surveys Focused on Species, Guilds, and Ecosystems

NASA Astrophysics Data System (ADS)

Rudd, Murray A.; Andres, Sheri; Kilfoil, Mary

2016-09-01

Accounting for non-market economic values of biological diversity is important to fully assess the benefits of environmental policies and regulations. This study used three choice experiments (species-, guild-, and ecosystem-based surveys) in parallel to quantify non-use values for little-known aquatic species at risk in southern Ontario. Mean willingness-to-pay (WTP) ranged from 9.45 to 21.41 per listing status increment under Canada's Species at Risk Act for both named and unnamed little-known species. Given the broad range of valuable ecosystem services likely to accrue to residents from substantial increases in water quality and the rehabilitation of coastal wetlands, the difference in WTP between species- and ecosystem-based surveys seemed implausibly small. It appeared that naming species—the `iconization' of species in two of the three surveys—had an important effect on WTP. The results suggest that reasonable annual household-level WTP values for little-known aquatic species may be 10 to 25 per species or 10 to 20 per listing status increment. The results highlighted the utility of using parallel surveys to triangulate on non-use economic values for little-known species at risk.

Non-use Economic Values for Little-Known Aquatic Species at Risk: Comparing Choice Experiment Results from Surveys Focused on Species, Guilds, and Ecosystems.

PubMed

Rudd, Murray A; Andres, Sheri; Kilfoil, Mary

2016-09-01

Accounting for non-market economic values of biological diversity is important to fully assess the benefits of environmental policies and regulations. This study used three choice experiments (species-, guild-, and ecosystem-based surveys) in parallel to quantify non-use values for little-known aquatic species at risk in southern Ontario. Mean willingness-to-pay (WTP) ranged from $9.45 to $21.41 per listing status increment under Canada's Species at Risk Act for both named and unnamed little-known species. Given the broad range of valuable ecosystem services likely to accrue to residents from substantial increases in water quality and the rehabilitation of coastal wetlands, the difference in WTP between species- and ecosystem-based surveys seemed implausibly small. It appeared that naming species-the 'iconization' of species in two of the three surveys-had an important effect on WTP. The results suggest that reasonable annual household-level WTP values for little-known aquatic species may be $10 to $25 per species or $10 to $20 per listing status increment. The results highlighted the utility of using parallel surveys to triangulate on non-use economic values for little-known species at risk.

Biodiversity effects in the wild are common and as strong as key drivers of productivity.

PubMed

Duffy, J Emmett; Godwin, Casey M; Cardinale, Bradley J

2017-09-14

More than 500 controlled experiments have collectively suggested that biodiversity loss reduces ecosystem productivity and stability. Yet the importance of biodiversity in sustaining the world's ecosystems remains controversial, largely because of the lack of validation in nature, where strong abiotic forcing and complex interactions are assumed to swamp biodiversity effects. Here we test this assumption by analysing 133 estimates reported in 67 field studies that statistically separated the effects of biodiversity on biomass production from those of abiotic forcing. Contrary to the prevailing opinion of the previous two decades that biodiversity would have rare or weak effects in nature, we show that biomass production increases with species richness in a wide range of wild taxa and ecosystems. In fact, after controlling for environmental covariates, increases in biomass with biodiversity are stronger in nature than has previously been documented in experiments and comparable to or stronger than the effects of other well-known drivers of productivity, including climate and nutrient availability. These results are consistent with the collective experimental evidence that species richness increases community biomass production, and suggest that the role of biodiversity in maintaining productive ecosystems should figure prominently in global change science and policy.

Understanding the value of plant diversity for ecosystem functioning through niche theory

PubMed Central

Isbell, Forest; Purves, Drew W.; Loreau, Michel

2016-01-01

Biodiversity experiments have generated robust empirical results supporting the hypothesis that ecosystems function better when they contain more species. Given that ecosystems provide services that are valued by humans, this inevitably suggests that the loss of species from natural ecosystems could diminish their value. This raises two important questions. First, will experimental results translate into the real world, where species are being lost at an alarming rate? And second, what are the benefits and pitfalls of such valuation exercises? We argue that the empirical results obtained in experiments are entirely consistent with well-established theories of species coexistence. We then examine the current body of work through the lens of niche theory and highlight where closer links with theory could open up opportunities for future research. We argue that niche theory predicts that diversity–functioning relationships are likely to be stronger (and require more species) in the field than in simplified experimental settings. However, we caution that while many of the biological processes that promote coexistence can also generate diversity–function relationships, there is no simple mapping between the two. This implies that valuation exercises need to proceed with care. PMID:27928043

Understanding the value of plant diversity for ecosystem functioning through niche theory.

PubMed

Turnbull, Lindsay A; Isbell, Forest; Purves, Drew W; Loreau, Michel; Hector, Andy

2016-12-14

Biodiversity experiments have generated robust empirical results supporting the hypothesis that ecosystems function better when they contain more species. Given that ecosystems provide services that are valued by humans, this inevitably suggests that the loss of species from natural ecosystems could diminish their value. This raises two important questions. First, will experimental results translate into the real world, where species are being lost at an alarming rate? And second, what are the benefits and pitfalls of such valuation exercises? We argue that the empirical results obtained in experiments are entirely consistent with well-established theories of species coexistence. We then examine the current body of work through the lens of niche theory and highlight where closer links with theory could open up opportunities for future research. We argue that niche theory predicts that diversity-functioning relationships are likely to be stronger (and require more species) in the field than in simplified experimental settings. However, we caution that while many of the biological processes that promote coexistence can also generate diversity-function relationships, there is no simple mapping between the two. This implies that valuation exercises need to proceed with care. © 2016 The Author(s).

Responses of ecosystem water use efficiency to spring snow and summer water addition with or without nitrogen addition in a temperate steppe

PubMed Central

Zhai, Penghui; Huang, Jianhui; Zhao, Xiang; Dong, Kuanhu

2018-01-01

Water use efficiency (WUE) is an important indicator of ecosystem functioning but how ecosystem WUE responds to climate change including precipitation and nitrogen (N) deposition increases is still unknown. To investigate such responses, an experiment with a randomized block design with water (spring snowfall or summer water addition) and nitrogen addition was conducted in a temperate steppe of northern China. We investigated net ecosystem CO2 production (NEP), gross ecosystem production (GEP) and evapotranspiration (ET) to calculate ecosystem WUE (WUEnep = NEP/ET or WUEgep = GEP/ET) under spring snow and summer water addition with or without N addition from 2011 to 2013. The results showed that spring snow addition only had significant effect on ecosystem WUE in 2013 and summer water addition showed positive effect on ecosystem WUE in 2011 and 2013, as their effects on NEP and GEP is stronger than ET. N addition increased ecosystem WUE in 2012 and 2013 both in spring snow addition and summer water addition for its increasing effects on NEP and GEP but no effect on ET. Summer water addition had less but N addition had greater increasing effects on ecosystem WUE as natural precipitation increase indicating that natural precipitation regulates ecosystem WUE responses to water and N addition. Moreover, WUE was tightly related with atmospheric vapor-pressure deficit (VPD), photosynthetic active radiation (PAR), precipitation and soil moisture indicating the regulation of climate drivers on ecosystem WUE. In addition, it also was affected by aboveground net primary production (ANPP). The study suggests that ecosystem WUE responses to water and N addition is determined by the change in carbon process rather than that in water process, which are regulated by climate change in the temperate steppe of northern China. PMID:29529082

Responses of ecosystem water use efficiency to spring snow and summer water addition with or without nitrogen addition in a temperate steppe.

PubMed

Zhang, Xiaolin; Zhai, Penghui; Huang, Jianhui; Zhao, Xiang; Dong, Kuanhu

2018-01-01

Water use efficiency (WUE) is an important indicator of ecosystem functioning but how ecosystem WUE responds to climate change including precipitation and nitrogen (N) deposition increases is still unknown. To investigate such responses, an experiment with a randomized block design with water (spring snowfall or summer water addition) and nitrogen addition was conducted in a temperate steppe of northern China. We investigated net ecosystem CO2 production (NEP), gross ecosystem production (GEP) and evapotranspiration (ET) to calculate ecosystem WUE (WUEnep = NEP/ET or WUEgep = GEP/ET) under spring snow and summer water addition with or without N addition from 2011 to 2013. The results showed that spring snow addition only had significant effect on ecosystem WUE in 2013 and summer water addition showed positive effect on ecosystem WUE in 2011 and 2013, as their effects on NEP and GEP is stronger than ET. N addition increased ecosystem WUE in 2012 and 2013 both in spring snow addition and summer water addition for its increasing effects on NEP and GEP but no effect on ET. Summer water addition had less but N addition had greater increasing effects on ecosystem WUE as natural precipitation increase indicating that natural precipitation regulates ecosystem WUE responses to water and N addition. Moreover, WUE was tightly related with atmospheric vapor-pressure deficit (VPD), photosynthetic active radiation (PAR), precipitation and soil moisture indicating the regulation of climate drivers on ecosystem WUE. In addition, it also was affected by aboveground net primary production (ANPP). The study suggests that ecosystem WUE responses to water and N addition is determined by the change in carbon process rather than that in water process, which are regulated by climate change in the temperate steppe of northern China.

Shell Games. VORTEX: Virginia's Oyster Reef Teaching EXperience.

ERIC Educational Resources Information Center

Harding, Juliana M.; Mann, Roger; Clark, Vicki P.

This document introduces Virginia's Oyster Reef Teaching EXperience (VORTEX), which is an interdisciplinary program focusing on the importance of oyster reef communities in the Chesapeake Bay ecosystem. The VORTEX program uses field and laboratory experiences supported by multimedia instruction. This document presents an overview on the biology of…

An open source platform for multi-scale spatially distributed simulations of microbial ecosystems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Segre, Daniel

2014-08-14

The goal of this project was to develop a tool for facilitating simulation, validation and discovery of multiscale dynamical processes in microbial ecosystems. This led to the development of an open-source software platform for Computation Of Microbial Ecosystems in Time and Space (COMETS). COMETS performs spatially distributed time-dependent flux balance based simulations of microbial metabolism. Our plan involved building the software platform itself, calibrating and testing it through comparison with experimental data, and integrating simulations and experiments to address important open questions on the evolution and dynamics of cross-feeding interactions between microbial species.

Biotic Processes Regulating the Carbon Balance of Desert Ecosystems - Final Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nowak, Robert S; Smith, Stanley D; Evans, Dave

2012-12-13

Our results from the 10-year elevated atmospheric CO{sub 2} concentration study at the Nevada Desert FACE (Free-air CO{sub 2} Enrichment) Facility (NDFF) indicate that the Mojave Desert is a dynamic ecosystem with the capacity to respond quickly to environmental changes. The Mojave Desert ecosystem is accumulating carbon (C), and over the 10-year experiment, C accumulation was significantly greater under elevated [CO{sub 2}] than under ambient, despite great fluctuations in C inputs from year to year and even apparent reversals in which [CO{sub 2}] treatment had greater C accumulations.

Modeling forest C and N allocation responses to free-air CO2 enrichment

NASA Astrophysics Data System (ADS)

Luus, Kristina; De Kauwe, Martin; Walker, Anthony; Werner, Christian; Iversen, Colleen; McCarthy, Heather; Medlyn, Belinda; Norby, Richard; Oren, Ram; Zak, Donald; Zaehle, Sönke

2015-04-01

Vegetation allocation patterns and soil-vegetation partitioning of C and N are predicted to change in response to rising atmospheric concentrations of CO2. These allocation responses to rising CO2 have been examined at the ecosystem level through through free-air CO2 enrichment (FACE) experiments, and their global implications for the timing of progressive N limitation (PNL) and C sequestration have been predicted for ~100 years using a variety of ecosystem models. However, recent FACE model-data syntheses studies [1,2,3] have indicated that ecosystem models do not capture the 5-10 year site-level ecosystem allocation responses to elevated CO2. This may be due in part to the missing representation of the rhizosphere interactions between plants and soil biota in models. Ecosystem allocation of C and N is altered by interactions between soil and vegetation through the priming effect: as plant N availability diminishes, plants respond physiologically by altering their tissue allocation strategies so as to increase rates of root growth and rhizodeposition. In response, either soil organic material begins to accumulate, which hastens the onset of PNL, or soil microbes start to decompose C more rapidly, resulting in increased N availability for plant uptake, which delays PNL. In this study, a straightforward approach for representing rhizosphere interactions in ecosystem models was developed through which C and N allocation to roots and rhizodeposition responds dynamically to elevated CO2 conditions, modifying soil decomposition rates without pre-specification of the direction in which soil C and N accumulation should shift in response to elevated CO2. This approach was implemented in a variety of ecosystem models ranging from stand (G'DAY), to land surface (CLM 4.5, O-CN), to dynamic global vegetation (LPJ-GUESS) models. Comparisons against data from three forest FACE sites (Duke, Oak Ridge & Rhinelander) indicated that representing rhizosphere interactions allowed models to more reliably capture responses of ecosystem C and N allocation to free-air CO2 enrichment because they were able to simulate the priming effect. Insights were therefore gained into between-site differences observed in forest FACE experiments, and the underlying physiological and biogeochemical mechanisms determining ecosystem C and N allocation responses to elevated CO2. References 1. De Kauwe, M. G., et al. (2014), Where does the carbon go? A model-data intercomparison of vegetation carbon allocation and turnover processes at two temperate forest free-air CO2 enrichment sites, New Phytologist, 203, 883-899. 2. Walker, A. P., et al. (2014), Comprehensive ecosystem model-data synthesis using multiple data sets at two temperate forest free-air CO2 enrichment experiments: Model performance at ambient CO2 concentration, Journal of Geophysical Research: Biogeosciences, 119, 937-964. 3. Zaehle, S., et al. (2014), Evaluation of 11 terrestrial carbon-nitrogen cycle models against observations from two temperate Free-Air CO2 Enrichment studies, New Phytologist, 202 (3), 803-822.

Paying for Forest Ecosystem Services: Voluntary Versus Mandatory Payments.

PubMed

Roesch-McNally, Gabrielle E; Rabotyagov, Sergey S

2016-03-01

The emergence of new markets for forest ecosystem services can be a compelling opportunity for market diversification for private forest landowners, while increasing the provision of public goods from private lands. However, there is limited information available on the willingness-to-pay (WTP) for specific forest ecosystem services, particularly across different ecosystem market mechanisms. We utilize survey data from Oregon and Washington households to compare marginal WTP for forest ecosystem services and the total WTP for cost-effective bundles of forest ecosystem services obtained from a typical Pacific Northwest forest across two value elicitation formats representing two different ecosystem market mechanisms: an incentive-compatible choice experiment involving mandatory tax payments and a hypothetical private provision scenario modeled as eliciting contributions to the preferred forest management alternative via a provision point mechanism with a refund. A representative household's total WTP for the average forest management program was estimated at $217.59 per household/year under a mandatory tax mechanism and $160.44 per household/per year under a voluntary, crowdfunding-style, contribution mechanism; however, these estimates are not statistically different. Marginal WTP estimates were assessed for particular forest ecosystem service attributes including water quality, carbon storage, mature forest habitat, and public recreational access. This study finds that survey respondents place significant economic value on forest ecosystem services in both elicitation formats and that the distributions of the marginal WTP are not statistically significantly different.

Ecosystem carbon exchange in response to locust outbreaks in a temperate steppe.

PubMed

Song, Jian; Wu, Dandan; Shao, Pengshuai; Hui, Dafeng; Wan, Shiqiang

2015-06-01

It is predicted that locust outbreaks will occur more frequently under future climate change scenarios, with consequent effects on ecological goods and services. A field manipulative experiment was conducted to examine the responses of gross ecosystem productivity (GEP), net ecosystem carbon dioxide (CO2) exchange (NEE), ecosystem respiration (ER), and soil respiration (SR) to locust outbreaks in a temperate steppe of northern China from 2010 to 2011. Two processes related to locust outbreaks, natural locust feeding and carcass deposition, were mimicked by clipping 80 % of aboveground biomass and adding locust carcasses, respectively. Ecosystem carbon (C) exchange (i.e., GEP, NEE, ER, and SR) was suppressed by locust feeding in 2010, but stimulated by locust carcass deposition in both years (except SR in 2011). Experimental locust outbreaks (i.e., clipping plus locust carcass addition) decreased GEP and NEE in 2010 whereas they increased GEP, NEE, and ER in 2011, leading to neutral changes in GEP, NEE, and SR across the 2 years. The responses of ecosystem C exchange could have been due to the changes in soil ammonium nitrogen, community cover, and aboveground net primary productivity. Our findings of the transient and neutral changes in ecosystem C cycling under locust outbreaks highlight the importance of resistance, resilience, and stability of the temperate steppe in maintaining reliable ecosystem services, and facilitate the projections of ecosystem functioning in response to natural disturbance and climate change.

Paying for Forest Ecosystem Services: Voluntary Versus Mandatory Payments

NASA Astrophysics Data System (ADS)

Roesch-McNally, Gabrielle E.; Rabotyagov, Sergey S.

2016-03-01

The emergence of new markets for forest ecosystem services can be a compelling opportunity for market diversification for private forest landowners, while increasing the provision of public goods from private lands. However, there is limited information available on the willingness-to-pay (WTP) for specific forest ecosystem services, particularly across different ecosystem market mechanisms. We utilize survey data from Oregon and Washington households to compare marginal WTP for forest ecosystem services and the total WTP for cost-effective bundles of forest ecosystem services obtained from a typical Pacific Northwest forest across two value elicitation formats representing two different ecosystem market mechanisms: an incentive-compatible choice experiment involving mandatory tax payments and a hypothetical private provision scenario modeled as eliciting contributions to the preferred forest management alternative via a provision point mechanism with a refund. A representative household's total WTP for the average forest management program was estimated at 217.59 per household/year under a mandatory tax mechanism and 160.44 per household/per year under a voluntary, crowdfunding-style, contribution mechanism; however, these estimates are not statistically different. Marginal WTP estimates were assessed for particular forest ecosystem service attributes including water quality, carbon storage, mature forest habitat, and public recreational access. This study finds that survey respondents place significant economic value on forest ecosystem services in both elicitation formats and that the distributions of the marginal WTP are not statistically significantly different.

Synergy of extreme drought and shrub invasion reduce ecosystem functioning and resilience in water-limited climates

PubMed Central

Caldeira, Maria C.; Lecomte, Xavier; David, Teresa S.; Pinto, Joaquim G.; Bugalho, Miguel N.; Werner, Christiane

2015-01-01

Extreme drought events and plant invasions are major drivers of global change that can critically affect ecosystem functioning and alter ecosystem-atmosphere exchange. Invaders are expanding worldwide and extreme drought events are projected to increase in frequency and intensity. However, very little is known on how these drivers may interact to affect the functioning and resilience of ecosystems to extreme events. Using a manipulative shrub removal experiment and the co-occurrence of an extreme drought event (2011/2012) in a Mediterranean woodland, we show that native shrub invasion and extreme drought synergistically reduced ecosystem transpiration and the resilience of key-stone oak tree species. Ecosystem transpiration was dominated by the water use of the invasive shrub Cistus ladanifer, which further increased after the extreme drought event. Meanwhile, the transpiration of key-stone tree species decreased, indicating a competitive advantage in favour of the invader. Our results suggest that in Mediterranean-type climates the invasion of water spending species and projected recurrent extreme drought events may synergistically cause critical drought tolerance thresholds of key-stone tree species to be surpassed, corroborating observed higher tree mortality in the invaded ecosystems. Ultimately, this may shift seasonally water limited ecosystems into less desirable alternative states dominated by water spending invasive shrubs. PMID:26461978

Synergy of extreme drought and shrub invasion reduce ecosystem functioning and resilience in water-limited climates.

PubMed

Caldeira, Maria C; Lecomte, Xavier; David, Teresa S; Pinto, Joaquim G; Bugalho, Miguel N; Werner, Christiane

2015-10-13

Extreme drought events and plant invasions are major drivers of global change that can critically affect ecosystem functioning and alter ecosystem-atmosphere exchange. Invaders are expanding worldwide and extreme drought events are projected to increase in frequency and intensity. However, very little is known on how these drivers may interact to affect the functioning and resilience of ecosystems to extreme events. Using a manipulative shrub removal experiment and the co-occurrence of an extreme drought event (2011/2012) in a Mediterranean woodland, we show that native shrub invasion and extreme drought synergistically reduced ecosystem transpiration and the resilience of key-stone oak tree species. Ecosystem transpiration was dominated by the water use of the invasive shrub Cistus ladanifer, which further increased after the extreme drought event. Meanwhile, the transpiration of key-stone tree species decreased, indicating a competitive advantage in favour of the invader. Our results suggest that in Mediterranean-type climates the invasion of water spending species and projected recurrent extreme drought events may synergistically cause critical drought tolerance thresholds of key-stone tree species to be surpassed, corroborating observed higher tree mortality in the invaded ecosystems. Ultimately, this may shift seasonally water limited ecosystems into less desirable alternative states dominated by water spending invasive shrubs.

Synergy of extreme drought and shrub invasion reduce ecosystem functioning and resilience in water-limited climates

NASA Astrophysics Data System (ADS)

Caldeira, Maria C.; Lecomte, Xavier; David, Teresa S.; Pinto, Joaquim G.; Bugalho, Miguel N.; Werner, Christiane

2015-10-01

Extreme drought events and plant invasions are major drivers of global change that can critically affect ecosystem functioning and alter ecosystem-atmosphere exchange. Invaders are expanding worldwide and extreme drought events are projected to increase in frequency and intensity. However, very little is known on how these drivers may interact to affect the functioning and resilience of ecosystems to extreme events. Using a manipulative shrub removal experiment and the co-occurrence of an extreme drought event (2011/2012) in a Mediterranean woodland, we show that native shrub invasion and extreme drought synergistically reduced ecosystem transpiration and the resilience of key-stone oak tree species. Ecosystem transpiration was dominated by the water use of the invasive shrub Cistus ladanifer, which further increased after the extreme drought event. Meanwhile, the transpiration of key-stone tree species decreased, indicating a competitive advantage in favour of the invader. Our results suggest that in Mediterranean-type climates the invasion of water spending species and projected recurrent extreme drought events may synergistically cause critical drought tolerance thresholds of key-stone tree species to be surpassed, corroborating observed higher tree mortality in the invaded ecosystems. Ultimately, this may shift seasonally water limited ecosystems into less desirable alternative states dominated by water spending invasive shrubs.

Crab regulation of cross-ecosystem resource transfer by marine foraging fire ants.

PubMed

Garcia, Erica A; Bertness, Mark D; Alberti, Juan; Silliman, Brian R

2011-08-01

Permeability of boundaries in biological systems is regulated by biotic and/or abiotic factors. Despite this knowledge, the role of biotic factors in regulating resource transfer across ecosystem boundaries has received little study. Additionally, little is known about how cross-ecosystem resource transfer affects source populations. We used experiments, observations and stable isotopes, to evaluate: (1) the proportion of intertidal-foraging black fire ant (Solenopsis richteri) diet derived from marine sources, (2) how black fire ant cross-ecosystem resource transfer is altered by the dominant bioengineer in the intertidal, a burrowing crab (Neohelice granulata), (3) the top-down impact of these terrestrial ants on a marine resource, and (4) the effect of marine resources on recipient black fire ants. We found that more than 85% of the black fire ant diet is derived from marine sources, the number of intertidal foraging ants doubles in the absence of crab burrows, and that ants cause a 50% reduction in intertidal polychaetes. Also, ant mound density is three times greater adjacent to marine systems. This study reveals that cross-ecosystem foraging terrestrial ants can clearly have strong impacts on marine resources. Furthermore, ecosystem engineers that modify and occupy habitat in these ecosystem boundaries can strongly regulate the degree of cross-ecosystem resource transfer and resultant top down impacts.

Transpiration Dominates Ecosystem Water-Use Efficiency in Response to Warming in an Alpine Meadow

NASA Astrophysics Data System (ADS)

Quan, Quan; Zhang, Fangyue; Tian, Dashuan; Zhou, Qingping; Wang, Lixin; Niu, Shuli

2018-02-01

As a key linkage of C and water cycles, water-use efficiency (WUE) quantifies how much water an ecosystem uses for carbon gain. Although ecosystem C and water fluxes have been intensively studied, yet it remains unclear how ecosystem WUE responds to climate warming and which processes dominate the response of WUE. To answer these questions, we examined canopy WUE (WUEc), ecosystem WUE (WUEe) and their components including gross ecosystem productivity, ecosystem evapotranspiration (ET), soil evaporation (E), and plant canopy transpiration (T), in response to warming in an alpine meadow by using a manipulative warming experiment in 2015 and 2016. As expected, low- and high-level warming treatments increased soil temperature (Tsoil) at 10 cm on average by 1.65 and 2.77°C, but decreased soil moisture (Msoil) by 2.52 and 7.6 vol %, respectively, across the two years. Low- and high-level warming increased WUEe by 7.7 and 9.3% over the two years, but rarely changed WUEc in either year. T/ET ratio determined the differential responses of WUEc and WUEe. Larger T/ET led to less difference between WUEc and WUEe. By partitioning WUEc and WUEe into different carbon and water fluxes, we found that T rather than gross ecosystem productivity or E dominated the responses of WUEc and WUEe to warming. This study provides empirical insights into how ecosystem WUE responds to warming and illustrates the importance of plant transpiration in regulating ecosystem WUE under future climate change.

Effects of rodent-induced land degradation on ecosytem carbon fluxes in alpine meadow in the Qinghai-Tibet Plateau, China

NASA Astrophysics Data System (ADS)

Peng, F.; Quangang, Y.; Xue, X.; Guo, J.; Wang, T.

2014-10-01

Land degradation induced by rodent activities is extensively occurred in alpine meadow ecosystem in the Qinghai-Tibet Plateau that would affect the ecosystem carbon (C) balance. We conducted a field experiment with six levels of land degradation (D1-D6, degradation aggravates from D1 to D6) to investigate the effects of land degradation on ecosystem C fluxes. Soil respiration (Rs), net ecosystem exchange (NEE), ecosystem respiration (ER) and gross ecosystem production (GEP) were measured from June to September 2012. Soil respiration, ER, GEP and above-ground biomass (AGB) was significantly higher in slightly degraded (D3 and D6) than in severely degraded land (D1, D2, D4 and D5). Positive averages of NEE in the growing season indicate that alpine meadow ecosystem is a weak C sink during the growing season. Net ecosystem exchange had no significant difference among different degraded levels, but the average NEE in slightly degraded group was 33.6% higher than in severely degraded group. Soil respiration, ER and NEE were positively correlated with AGB whereas soil organic C, labile soil C, total nitrogen (N) and inorganic nitrogen were associated with root biomass (RB). Our results highlight the decline of vegetation C storage of alpine meadow ecosystem with increasing number of rodent holes and suggest the control of AGB on ecosystem C fluxes, and the control of RB on soil C and N with development of land degradation.

Fire and aquatic ecosystems of the western USA: Current knowledge and key questions

USGS Publications Warehouse

Bisson, P.A.; Rieman, B.; Luce, C.; Hessburg, Paul F.; Lee, D.; Kershner, J.; Reeves, G.H.; Gresswell, Robert E.

2003-01-01

Understanding of the effects of wildland fire and fire management on aquatic and riparian ecosystems is an evolving field, with many questions still to be resolved. Limitations of current knowledge, and the certainty that fire management will continue, underscore the need to summarize available information. Integrating fire and fuels management with aquatic ecosystem conservation begins with recognizing that terrestrial and aquatic ecosystems are linked and dynamic, and that fire can play a critical role in maintaining aquatic ecological diversity. To protect aquatic ecosystems we argue that it will be important to: (1) accommodate fire-related and other ecological processes that maintain aquatic habitats and biodiversity, and not simply control fires or fuels; (2) prioritize projects according to risks and opportunities for fire control and the protection of aquatic ecosystems; and (3) develop new consistency in the management and regulatory process. Ultimately, all natural resource management is uncertain; the role of science is to apply experimental design and hypothesis testing to management applications that affect fire and aquatic ecosystems. Policy-makers and the public will benefit from an expanded appreciation of fire ecology that enables them to implement watershed management projects as experiments with hypothesized outcomes, adequate controls, and replication.

Enhanced ergonomics approaches for product design: a user experience ecosystem perspective and case studies.

PubMed

Xu, Wei

2014-01-01

This paper first discusses the major inefficiencies faced in current human factors and ergonomics (HFE) approaches: (1) delivering an optimal end-to-end user experience (UX) to users of a solution across its solution lifecycle stages; (2) strategically influencing the product business and technology capability roadmaps from a UX perspective and (3) proactively identifying new market opportunities and influencing the platform architecture capabilities on which the UX of end products relies. In response to these challenges, three case studies are presented to demonstrate how enhanced ergonomics design approaches have effectively addressed the challenges faced in current HFE approaches. Then, the enhanced ergonomics design approaches are conceptualised by a user-experience ecosystem (UXE) framework, from a UX ecosystem perspective. Finally, evidence supporting the UXE, the advantage and the formalised process for executing UXE and methodological considerations are discussed. Practitioner Summary: This paper presents enhanced ergonomics approaches to product design via three case studies to effectively address current HFE challenges by leveraging a systematic end-to-end UX approach, UX roadmaps and emerging UX associated with prioritised user needs and usages. Thus, HFE professionals can be more strategic, creative and influential.

Assimilation of seasonal chlorophyll and nutrient data into an adjoint three-dimensional ocean carbon cycle model: Sensitivity analysis and ecosystem parameter optimization

NASA Astrophysics Data System (ADS)

Tjiputra, Jerry F.; Polzin, Dierk; Winguth, Arne M. E.

2007-03-01

An adjoint method is applied to a three-dimensional global ocean biogeochemical cycle model to optimize the ecosystem parameters on the basis of SeaWiFS surface chlorophyll observation. We showed with identical twin experiments that the model simulated chlorophyll concentration is sensitive to perturbation of phytoplankton and zooplankton exudation, herbivore egestion as fecal pellets, zooplankton grazing, and the assimilation efficiency parameters. The assimilation of SeaWiFS chlorophyll data significantly improved the prediction of chlorophyll concentration, especially in the high-latitude regions. Experiments that considered regional variations of parameters yielded a high seasonal variance of ecosystem parameters in the high latitudes, but a low variance in the tropical regions. These experiments indicate that the adjoint model is, despite the many uncertainties, generally capable to optimize sensitive parameters and carbon fluxes in the euphotic zone. The best fit regional parameters predict a global net primary production of 36 Pg C yr-1, which lies within the range suggested by Antoine et al. (1996). Additional constraints of nutrient data from the World Ocean Atlas showed further reduction in the model-data misfit and that assimilation with extensive data sets is necessary.

Nematomorph parasites indirectly alter the food web and ecosystem function of streams through behavioural manipulation of their cricket hosts.

PubMed

Sato, Takuya; Egusa, Tomohiro; Fukushima, Keitaro; Oda, Tomoki; Ohte, Nobuhito; Tokuchi, Naoko; Watanabe, Katsutoshi; Kanaiwa, Minoru; Murakami, Isaya; Lafferty, Kevin D

2012-08-01

Nematomorph parasites manipulate crickets to enter streams where the parasites reproduce. These manipulated crickets become a substantial food subsidy for stream fishes. We used a field experiment to investigate how this subsidy affects the stream community and ecosystem function. When crickets were available, predatory fish ate fewer benthic invertebrates. The resulting release of the benthic invertebrate community from fish predation indirectly decreased the biomass of benthic algae and slightly increased leaf break-down rate. This is the first experimental demonstration that host manipulation by a parasite can reorganise a community and alter ecosystem function. Nematomorphs are common, and many other parasites have dramatic effects on host phenotypes, suggesting that similar effects of parasites on ecosystems might be widespread. © 2012 Blackwell Publishing Ltd/CNRS.

Nematomorph parasites indirectly alter the food web and ecosystem function of streams through behavioural manipulation of their cricket hosts.

USGS Publications Warehouse

Sato, T.; Egusa, T.; Fukushima, K.; Oda, T.; Ohte, N.; Tokuchi, Naoko; Watanabe, Katsutoshi; Kanaiwa, Minoru; Murakami, Isaya; Lafferty, Kevin D.

2012-01-01

Nematomorph parasites manipulate crickets to enter streams where the parasites reproduce. These manipulated crickets become a substantial food subsidy for stream fishes. We used a field experiment to investigate how this subsidy affects the stream community and ecosystem function. When crickets were available, predatory fish ate fewer benthic invertebrates. The resulting release of the benthic invertebrate community from fish predation indirectly decreased the biomass of benthic algae and slightly increased leaf break-down rate. This is the first experimental demonstration that host manipulation by a parasite can reorganise a community and alter ecosystem function. Nematomorphs are common, and many other parasites have dramatic effects on host phenotypes, suggesting that similar effects of parasites on ecosystems might be widespread.

Diversity promotes temporal stability across levels of ecosystem organization in experimental grasslands.

PubMed

Proulx, Raphaël; Wirth, Christian; Voigt, Winfried; Weigelt, Alexandra; Roscher, Christiane; Attinger, Sabine; Baade, Jussi; Barnard, Romain L; Buchmann, Nina; Buscot, François; Eisenhauer, Nico; Fischer, Markus; Gleixner, Gerd; Halle, Stefan; Hildebrandt, Anke; Kowalski, Esther; Kuu, Annely; Lange, Markus; Milcu, Alex; Niklaus, Pascal A; Oelmann, Yvonne; Rosenkranz, Stephan; Sabais, Alexander; Scherber, Christoph; Scherer-Lorenzen, Michael; Scheu, Stefan; Schulze, Ernst-Detlef; Schumacher, Jens; Schwichtenberg, Guido; Soussana, Jean-François; Temperton, Vicky M; Weisser, Wolfgang W; Wilcke, Wolfgang; Schmid, Bernhard

2010-10-13

The diversity-stability hypothesis states that current losses of biodiversity can impair the ability of an ecosystem to dampen the effect of environmental perturbations on its functioning. Using data from a long-term and comprehensive biodiversity experiment, we quantified the temporal stability of 42 variables characterizing twelve ecological functions in managed grassland plots varying in plant species richness. We demonstrate that diversity increases stability i) across trophic levels (producer, consumer), ii) at both the system (community, ecosystem) and the component levels (population, functional group, phylogenetic clade), and iii) primarily for aboveground rather than belowground processes. Temporal synchronization across studied variables was mostly unaffected with increasing species richness. This study provides the strongest empirical support so far that diversity promotes stability across different ecological functions and levels of ecosystem organization in grasslands.

Whole-ecosystem experimental manipulations of tropical forests.

PubMed

Fayle, Tom M; Turner, Edgar C; Basset, Yves; Ewers, Robert M; Reynolds, Glen; Novotny, Vojtech

2015-06-01

Tropical forests are highly diverse systems involving extraordinary numbers of interactions between species, with each species responding in a different way to the abiotic environment. Understanding how these systems function and predicting how they respond to anthropogenic global change is extremely challenging. We argue for the necessity of 'whole-ecosystem' experimental manipulations, in which the entire ecosystem is targeted, either to reveal the functioning of the system in its natural state or to understand responses to anthropogenic impacts. We survey the current range of whole-ecosystem manipulations, which include those targeting weather and climate, nutrients, biotic interactions, human impacts, and habitat restoration. Finally we describe the unique challenges and opportunities presented by such projects and suggest directions for future experiments. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Evaluating Productivity Predictions Under Elevated CO2 Conditions: Multi-Model Benchmarking Across FACE Experiments

NASA Astrophysics Data System (ADS)

Cowdery, E.; Dietze, M.

2016-12-01

As atmospheric levels of carbon dioxide levels continue to increase, it is critical that terrestrial ecosystem models can accurately predict ecological responses to the changing environment. Current predictions of net primary productivity (NPP) in response to elevated atmospheric CO2 concentration are highly variable and contain a considerable amount of uncertainty.The Predictive Ecosystem Analyzer (PEcAn) is an informatics toolbox that wraps around an ecosystem model and can be used to help identify which factors drive uncertainty. We tested a suite of models (LPJ-GUESS, MAESPA, GDAY, CLM5, DALEC, ED2), which represent a range from low to high structural complexity, across a range of Free-Air CO2 Enrichment (FACE) experiments: the Kennedy Space Center Open Top Chamber Experiment, the Rhinelander FACE experiment, the Duke Forest FACE experiment and the Oak Ridge Experiment on CO2 Enrichment. These tests were implemented in a novel benchmarking workflow that is automated, repeatable, and generalized to incorporate different sites and ecological models. Observational data from the FACE experiments represent a first test of this flexible, extensible approach aimed at providing repeatable tests of model process representation.To identify and evaluate the assumptions causing inter-model differences we used PEcAn to perform model sensitivity and uncertainty analysis, not only to assess the components of NPP, but also to examine system processes such nutrient uptake and and water use. Combining the observed patterns of uncertainty between multiple models with results of the recent FACE-model data synthesis project (FACE-MDS) can help identify which processes need further study and additional data constraints. These findings can be used to inform future experimental design and in turn can provide informative starting point for data assimilation.

Allelochemicals and activities in a replanted Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) tree ecosystem.

PubMed

Kong, C H; Chen, L C; Xu, X H; Wang, P; Wang, S L

2008-12-24

Autotoxicity is a major reason for replant problems in managed tree ecosystems. Studies have related phenolics-based allelochemicals to autotoxicity. We selected a 20-year-old replanted Chinese fir [Cunninghamia lancealata (Lamb.) Hook] tree ecosystem to isolate, identify, determine the biological activity of, and quantify soil phytotoxins. Eight common phenolics (coumarin, vanillin, isovanillin, and p-hydroxybenzoic, vanillic, benzoic, cinnamic, and ferulic acids), friedelin, and a novel cyclic dipeptide (6-hydroxy-1,3-dimethyl-8-nonadecyl-[1,4]-diazocane-2,5-diketone) were obtained by using the bioassay-guided isolation technique from toxic soil of the replanted Chinese fir tree ecosystem. Chemical structures were determined by spectroscopic means, including 2D-NMR (COSY, HMQC, HMBC, and NOESY) experiments. High concentrations of soil phenolics and friedelin were observed in the natural evergreen broadleaf forest (CK) rather than in the Chinese fir tree ecosystem. The phenolics and friedelin were not phytotoxic to Chinese fir trees. However, the cyclic dipeptide inhibited Chinese fir growth at soil concentrations determined in the replanted Chinese fir tree ecosystem. There was a significantly higher soil concentration of cyclic dipeptide in the replanted Chinese fir tree ecosystem than in a fresh Chinese fir tree ecosystem. The results suggest that phenolics and friedelin are not key allelochemicals since they are weakly phytotoxic and are detected in low concentrations in the replanted Chinese fir tree ecosystem, while cyclic dipeptide is a highly active allelochemical with a phytotoxic effect that limits offspring growth in the replanted Chinese fir tree ecosystem. The discovery of cyclic dipeptide, as well as a further understanding of its potential action mechanism in the replanted Chinese fir tree ecosystem, may contribute to solving the replant problems in managed tree ecosystems.

Experimental droughts: Are precipitation variability and methodological trends hindering our understanding of ecological sensitivities to drought?

NASA Astrophysics Data System (ADS)

Hoover, D. L.; Wilcox, K.; Young, K. E.

2017-12-01

Droughts are projected to increase in frequency and intensity with climate change, which may have dramatic and prolonged effects on ecosystem structure and function. There are currently hundreds of published, ongoing, and new drought experiments worldwide aimed to assess ecosystem sensitivities to drought and identify the mechanisms governing ecological resistance and resilience. However, to date, the results from these experiments have varied widely, and thus patterns of drought sensitivities have been difficult to discern. This lack of consensus at the field scale, limits the abilities of experiments to help improve land surface models, which often fail to realistically simulate ecological responses to extreme events. This is unfortunate because models offer an alternative, yet complementary approach to increase the spatial and temporal assessment of ecological sensitivities to drought that are not possible in the field due to logistical and financial constraints. Here we examined 89 published drought experiments, along with their associated historical precipitation records to (1) identify where and how drought experiments have been imposed, (2) determine the extremity of drought treatments in the context of historical climate, and (3) assess the influence of precipitation variability on drought experiments. We found an overall bias in drought experiments towards short-term, extreme experiments in water-limited ecosystems. When placed in the context of local historical precipitation, most experimental droughts were extreme, with 61% below the 5th, and 43% below the 1st percentile. Furthermore, we found that interannual precipitation variability had a large and potentially underappreciated effect on drought experiments due to the co-varying nature of control and drought treatments. Thus detecting ecological effects in experimental droughts is strongly influenced by the interaction between drought treatment magnitude, precipitation variability, and key physiological thresholds. The results from this study have important implication for the design and interpretation of drought experiments as well as integrating field results with land surface models.

Few multiyear precipitation-reduction experiments find a shift in the productivity-precipitation relationship.

PubMed

Estiarte, Marc; Vicca, Sara; Peñuelas, Josep; Bahn, Michael; Beier, Claus; Emmett, Bridget A; Fay, Philip A; Hanson, Paul J; Hasibeder, Roland; Kigel, Jaime; Kröel-Dulay, Gyorgy; Larsen, Klaus Steenberg; Lellei-Kovács, Eszter; Limousin, Jean-Marc; Ogaya, Romà; Ourcival, Jean-Marc; Reinsch, Sabine; Sala, Osvaldo E; Schmidt, Inger Kappel; Sternberg, Marcelo; Tielbörger, Katja; Tietema, Albert; Janssens, Ivan A

2016-07-01

Well-defined productivity-precipitation relationships of ecosystems are needed as benchmarks for the validation of land models used for future projections. The productivity-precipitation relationship may be studied in two ways: the spatial approach relates differences in productivity to those in precipitation among sites along a precipitation gradient (the spatial fit, with a steeper slope); the temporal approach relates interannual productivity changes to variation in precipitation within sites (the temporal fits, with flatter slopes). Precipitation-reduction experiments in natural ecosystems represent a complement to the fits, because they can reduce precipitation below the natural range and are thus well suited to study potential effects of climate drying. Here, we analyse the effects of dry treatments in eleven multiyear precipitation-manipulation experiments, focusing on changes in the temporal fit. We expected that structural changes in the dry treatments would occur in some experiments, thereby reducing the intercept of the temporal fit and displacing the productivity-precipitation relationship downward the spatial fit. The majority of experiments (72%) showed that dry treatments did not alter the temporal fit. This implies that current temporal fits are to be preferred over the spatial fit to benchmark land-model projections of productivity under future climate within the precipitation ranges covered by the experiments. Moreover, in two experiments, the intercept of the temporal fit unexpectedly increased due to mechanisms that reduced either water loss or nutrient loss. The expected decrease of the intercept was observed in only one experiment, and only when distinguishing between the late and the early phases of the experiment. This implies that we currently do not know at which precipitation-reduction level or at which experimental duration structural changes will start to alter ecosystem productivity. Our study highlights the need for experiments with multiple, including more extreme, dry treatments, to identify the precipitation boundaries within which the current temporal fits remain valid. © 2016 John Wiley & Sons Ltd.

From observations to experiments in phenology research: investigating climate change impacts on trees and shrubs using dormant twigs.

PubMed

Primack, Richard B; Laube, Julia; Gallinat, Amanda S; Menzel, Annette

2015-11-01

Climate change is advancing the leaf-out times of many plant species and mostly extending the growing season in temperate ecosystems. Laboratory experiments using twig cuttings from woody plant species present an affordable, easily replicated approach to investigate the relative importance of factors such as winter chilling, photoperiod, spring warming and frost tolerance on the leafing-out times of plant communities. This Viewpoint article demonstrates how the results of these experiments deepen our understanding beyond what is possible via analyses of remote sensing and field observation data, and can be used to improve climate change forecasts of shifts in phenology, ecosystem processes and ecological interactions. The twig method involves cutting dormant twigs from trees, shrubs and vines on a single date or at intervals over the course of the winter and early spring, placing them in containers of water in controlled environments, and regularly recording leaf-out, flowering or other phenomena. Prior to or following leaf-out or flowering, twigs may be assigned to treatment groups for experiments involving temperature, photoperiod, frost, humidity and more. Recent studies using these methods have shown that winter chilling requirements and spring warming strongly affect leaf-out and flowering times of temperate trees and shrubs, whereas photoperiod requirements are less important than previously thought for most species. Invasive plant species have weaker winter chilling requirements than native species in temperate ecosystems, and species that leaf-out early in the season have greater frost tolerance than later leafing species. This methodology could be extended to investigate additional drivers of leaf-out phenology, leaf senescence in the autumn, and other phenomena, and could be a useful tool for education and outreach. Additional ecosystems, such as boreal, southern hemisphere and sub-tropical forests, could also be investigated using dormant twigs to determine the drivers of leaf-out times and how these ecosystems will be affected by climate change. © The Author 2015. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Attributing Asymmetric Productivity Responses to Internal Ecosystem Dynamics and External Drivers Using Probabilistic Models

NASA Astrophysics Data System (ADS)

Parolari, A.; Goulden, M.

2017-12-01

A major challenge to interpreting asymmetric changes in ecosystem productivity is the attribution of these changes to external climate forcing or to internal ecophysiological processes that respond to these drivers (e.g., photosynthesis response to drying soil). For example, positive asymmetry in productivity can result from either positive skewness in the distribution of annual rainfall amount or from negative curvature in the productivity response to annual rainfall. To analyze the relative influences of climate and ecosystem dynamics on both positive and negative asymmetry in multi-year ANPP experiments, we use a multi-scale coupled ecosystem water-carbon model to interpret field experimental results that span gradients of rainfall skewness and ANPP response curvature. The model integrates rainfall variability, soil moisture dynamics, and net carbon assimilation from the daily to inter-annual scales. From the underlying physical basis of the model, we compute the joint probability distribution of the minimum and maximum ANPP for an annual ANPP experiment of N years. The distribution is used to estimate the likelihood that either positive or negative asymmetry will be observed in an experiment, given the annual rainfall distribution and the ANPP response curve. We estimate the total asymmetry as the mode of this joint distribution and the relative contribution attributable to rainfall skewness as the mode for a linear ANPP response curve. Applied to data from several long-term ANPP experiments, we find that there is a wide range of observed ANPP asymmetry (positive and negative) and a spectrum of contributions from internal and external factors. We identify the soil water holding capacity relative to the mean rain event depth as a critical ecosystem characteristic that controls the non-linearity of the ANPP response and positive curvature at high rainfall. Further, the seasonal distribution of rainfall is shown to control the presence or absence of negative curvature at low rainfall. Therefore, a combination of rooting depth, soil texture, and climate seasonality contribute to ANPP response curvature and its contribution to overall observed asymmetry.

Changes in ground layer vegetation following timber harvests on the Missouri Ozark Forest Ecosystem Project

Treesearch

Jennifer K. Grabner; Eric K. Zenner

2002-01-01

The Missouri Ozark Forest Ecosystem Project (MOFEP) is a landscape-scale experiment to test for effects of the following three common forest management practices on upland forests: 1) even-aged management (EAM), 2) uneven-aged management (UAM), and 3) no-harvest management (NHM). The first round of harvesting treatments was applied on the nine MOFEP sites in 1996. One...

Can current moisture responses predict soil CO2 efflux under altered precipitation regimes? A synthesis of manipulation experiments

Treesearch

S. Vicca; M. Bahn; M. Estiarte; E. E. van Loon; R. Vargas; G. Alberti; P. Ambus; M. A. Arain; C. Beier; L. P. Bentley; W. Borken; N. Buchmann; S. L. Collins; G. de Dato; J. S. Dukes; C. Escolar; P. Fay; G. Guidolotti; P. J. Hanson; A. Kahmen; G. Kröel-Dulay; T. Ladreiter-Knauss; K. S. Larsen; E. Lellei-Kovacs; E. Lebrija-Trejos; F. T. Maestre; S. Marhan; M. Marshall; P. Meir; Y. Miao; J. Muhr; P. A. Niklaus; R. Ogaya; J. Peñuelas; C. Poll; L. E. Rustad; K. Savage; A. Schindlbacher; I. K. Schmidt; A. R. Smith; E. D. Sotta; V. Suseela; A. Tietema; N. van Gestel; O. van Straaten; S. Wan; U. Weber; I. A. Janssens

2014-01-01

As a key component of the carbon cycle, soil CO2 efflux (SCE) is being increasingly studied to improve our mechanistic understanding of this important carbon flux. Predicting ecosystem responses to climate change often depends an extrapolation of current relationships between ecosystem processes and their climatic drivers to conditions not yet experienced by the...

Mechanisms of nitrogen retention in forest ecosystems - A field experiment

NASA Technical Reports Server (NTRS)

Vitousek, P. M.; Matson, P. A.

1984-01-01

Intensive forest management led to elevated losses of nitrogen from a recently harvested loblolly pine plantation in North Carolina. Measurements of nitrogen-15 retention in the field demonstrated that microbial uptake of nitrogen during the decomposition of residual organic material was the most important process retaining nitrogen. Management practices that remove this material cause increased losses of nitrogen to aquatic ecosystems and the atmosphere.

Spatial and temporal patterns in water chemistry of two high elevation lakes in southeast Wyoming

Treesearch

Robert C. Musselman

1995-01-01

The Glacier Lakes Ecosystem Experiments Site (GLEES) was established to examine the effects of atmospheric deposition and climate change on alpine and subalpine ecosystems. The site contains East Glacier Lake (3282 m elevation) and West Glacier Lake (3276 m elevation), and their watersheds. These two small lakes are located 120m from each other at the alpine/subalpine...

Effects of nitrogen additions on above- and belowground carbon dynamics in two tropical forests

Treesearch

Daniela F. Cusack; Whendee L. Silver; Margaret S. Torn; William H. McDowell

2011-01-01

Anthropogenic nitrogen (N) deposition is increasing rapidly in tropical regions, adding N to ecosystems that often have high background N availability. Tropical forests play an important role in the global carbon (C) cycle, yet the effects of N deposition on C cycling in these ecosystems are poorly understood. We used a field N-fertilization experiment in lower and...

Ecosystem biogeochemistry model parameterization: Do more flux data result in a better model in predicting carbon flux?

DOE PAGES

Zhu, Qing; Zhuang, Qianlai

2015-12-21

Reliability of terrestrial ecosystem models highly depends on the quantity and quality of thedata that have been used to calibrate the models. Nowadays, in situ observations of carbon fluxes areabundant. However, the knowledge of how much data (data length) and which subset of the time seriesdata (data period) should be used to effectively calibrate the model is still lacking. This study uses theAmeriFlux carbon flux data to parameterize the Terrestrial Ecosystem Model (TEM) with an adjoint-baseddata assimilation technique for various ecosystem types. Parameterization experiments are thus conductedto explore the impact of both data length and data period on the uncertaintymore » reduction of the posteriormodel parameters and the quantification of site and regional carbon dynamics. We find that: the modelis better constrained when it uses two-year data comparing to using one-year data. Further, two-year datais sufficient in calibrating TEM’s carbon dynamics, since using three-year data could only marginallyimprove the model performance at our study sites; the model is better constrained with the data thathave a higher‘‘climate variability’’than that having a lower one. The climate variability is used to measurethe overall possibility of the ecosystem to experience all climatic conditions including drought and extremeair temperatures and radiation; the U.S. regional simulations indicate that the effect of calibration datalength on carbon dynamics is amplified at regional and temporal scales, leading to large discrepanciesamong different parameterization experiments, especially in July and August. Our findings areconditioned on the specific model we used and the calibration sites we selected. The optimal calibrationdata length may not be suitable for other models. However, this study demonstrates that there may exist athreshold for calibration data length and simply using more data would not guarantee a better modelparameterization and prediction. More importantly, climate variability might be an effective indicator ofinformation within the data, which could help data selection for model parameterization. As a result, we believe ourfindings will benefit the ecosystem modeling community in using multiple-year data to improve modelpredictability.« less

Seed dispersal as an ecosystem service: frugivore loss leads to decline of a socially valued plant, Capsicum frutescens.

PubMed

Egerer, Monika H; Fricke, Evan C; Rogers, Haldre S

2018-04-01

Species interactions, both mutualistic and antagonistic, are widely recognized as providing important ecosystem services. Fruit-eating animals influence plant recruitment by increasing germination during gut passage and moving seeds away from conspecifics. However, relative to studies focused on the importance of frugivores for plant population maintenance, few studies target frugivores as ecosystem service providers, and frugivores are underappreciated as ecosystem service providers relative to other mutualists such as pollinators. Here, we use an accidental experiment to elucidate the role of seed dispersal by frugivores for maintaining a culturally and economically important plant, the donne' sali chili (Capsicum frutescens) in the Mariana Islands. One of the islands (Guam) has lost nearly all of its native forest birds due to an invasive snake (Boiga irregularis), whereas nearby islands have relatively intact bird populations. We hypothesized that frugivore loss would influence chili recruitment and abundance, which could have economic and cultural impacts. By using video cameras, we confirmed that birds were the primary seed dispersers. We used captive bird feeding trials to obtain gut-passed seeds to use in a seedling emergence experiment. The experiment showed that gut-passed seeds emerged sooner and at a higher proportion than seeds from whole fruits. Consistent with our findings that birds benefit chilies, we observed lower chili abundance on Guam than on islands with birds. In a survey questionnaire of island residents, the majority of residents reported an association between the wild chili and local cultural values and traditions. In addition, we identified a thriving market for chili products, suggesting benefits of wild chilies to people in the Marianas both as consumers and producers. Our study therefore documents seed dispersal as both a cultural and a supporting ecosystem service. We provide a comprehensive case study on how seed-dispersed plants decline in the absence of their disperser, and how to apply mixed-methods in ecosystem service assessments. Furthermore, we suggest that scientists and resource managers may utilize fruit-frugivore mutualisms concerning socially valuable plants to gather support for frugivore and forest conservation efforts. © 2018 The Authors Ecological Applications published by Wiley Periodicals, Inc. on behalf of Ecological Society of America.

Ecosystem biogeochemistry model parameterization: Do more flux data result in a better model in predicting carbon flux?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, Qing; Zhuang, Qianlai

Reliability of terrestrial ecosystem models highly depends on the quantity and quality of thedata that have been used to calibrate the models. Nowadays, in situ observations of carbon fluxes areabundant. However, the knowledge of how much data (data length) and which subset of the time seriesdata (data period) should be used to effectively calibrate the model is still lacking. This study uses theAmeriFlux carbon flux data to parameterize the Terrestrial Ecosystem Model (TEM) with an adjoint-baseddata assimilation technique for various ecosystem types. Parameterization experiments are thus conductedto explore the impact of both data length and data period on the uncertaintymore » reduction of the posteriormodel parameters and the quantification of site and regional carbon dynamics. We find that: the modelis better constrained when it uses two-year data comparing to using one-year data. Further, two-year datais sufficient in calibrating TEM’s carbon dynamics, since using three-year data could only marginallyimprove the model performance at our study sites; the model is better constrained with the data thathave a higher‘‘climate variability’’than that having a lower one. The climate variability is used to measurethe overall possibility of the ecosystem to experience all climatic conditions including drought and extremeair temperatures and radiation; the U.S. regional simulations indicate that the effect of calibration datalength on carbon dynamics is amplified at regional and temporal scales, leading to large discrepanciesamong different parameterization experiments, especially in July and August. Our findings areconditioned on the specific model we used and the calibration sites we selected. The optimal calibrationdata length may not be suitable for other models. However, this study demonstrates that there may exist athreshold for calibration data length and simply using more data would not guarantee a better modelparameterization and prediction. More importantly, climate variability might be an effective indicator ofinformation within the data, which could help data selection for model parameterization. As a result, we believe ourfindings will benefit the ecosystem modeling community in using multiple-year data to improve modelpredictability.« less

Dryland ecosystem responses to precipitation extremes and wildfire at a long-term rainfall manipulation experiment

NASA Astrophysics Data System (ADS)

Brown, R. F.; Collins, S. L.

2017-12-01

Climate is becoming increasingly more variable due to global environmental change, which is evidenced by fewer, but more extreme precipitation events, changes in precipitation seasonality, and longer, higher severity droughts. These changes, combined with a rising incidence of wildfire, have the potential to strongly impact net primary production (NPP) and key biogeochemical cycles, particularly in dryland ecosystems where NPP is sequentially limited by water and nutrient availability. Here we utilize a ten-year dataset from an ongoing long-term field experiment established in 2007 in which we experimentally altered monsoon rainfall variability to examine how our manipulations, along with naturally occurring events, affect NPP and associated biogeochemical cycles in a semi-arid grassland in central New Mexico, USA. Using long-term regional averages, we identified extremely wet monsoon years (242.8 mm, 2013), and extremely dry monsoon years (86.0 mm, 2011; 80.0 mm, 2015) and water years (117.0 mm, 2011). We examined how changes in precipitation variability and extreme events affected ecosystem processes and function particularly in the context of ecosystem recovery following a 2009 wildfire. Response variables included above- and below-ground plant biomass (ANPP & BNPP) and abundance, soil nitrogen availability, and soil CO2 efflux. Mean ANPP ranged from 3.6 g m-2 in 2011 to 254.5 g m-2 in 2013, while BNPP ranged from 23.5 g m-2 in 2015 to 194.2 g m-2 in 2013, demonstrating NPP in our semi-arid grassland is directly linked to extremes in both seasonal and annual precipitation. We also show increased nitrogen deposition positively affects NPP in unburned grassland, but has no significant impact on NPP post-fire except during extremely wet monsoon years. While soil respiration rates reflect lower ANPP post-fire, patterns in CO2 efflux have not been shown to change significantly in that efflux is greatest following large precipitation events preceded by longer drying periods. Current land surface models poorly represent dryland ecosystems, which frequently undergo extreme weather events. Our long-term experiment provides key insights into ecosystem processes and function, thereby providing capacity for model improvement particularly in the context of future environmental change.

Stream hydrology limits recovery of riparian ecosystems after wolf reintroduction

PubMed Central

Marshall, Kristin N.; Hobbs, N. Thompson; Cooper, David J.

2013-01-01

Efforts to restore ecosystems often focus on reintroducing apex predators to re-establish coevolved relationships among predators, herbivores and plants. The preponderance of evidence for indirect effects of predators on terrestrial plant communities comes from ecosystems where predators have been removed. Far less is known about the consequences of their restoration. The effects of removal and restoration are unlikely to be symmetrical because removing predators can create feedbacks that reinforce the effects of predator loss. Observational studies have suggested that the reintroduction of wolves to Yellowstone National Park initiated dramatic restoration of riparian ecosystems by releasing willows from excessive browsing by elk. Here, we present results from a decade-long experiment in Yellowstone showing that moderating browsing alone was not sufficient to restore riparian zones along small streams. Instead, restoration of willow communities depended on removing browsing and restoring hydrological conditions that prevailed before the removal of wolves. The 70-year absence of predators from the ecosystem changed the disturbance regime in a way that was not reversed by predator reintroduction. We conclude that predator restoration may not quickly repair effects of predator removal in ecosystems. PMID:23390108

Stream hydrology limits recovery of riparian ecosystems after wolf reintroduction.

PubMed

Marshall, Kristin N; Hobbs, N Thompson; Cooper, David J

2013-04-07

Efforts to restore ecosystems often focus on reintroducing apex predators to re-establish coevolved relationships among predators, herbivores and plants. The preponderance of evidence for indirect effects of predators on terrestrial plant communities comes from ecosystems where predators have been removed. Far less is known about the consequences of their restoration. The effects of removal and restoration are unlikely to be symmetrical because removing predators can create feedbacks that reinforce the effects of predator loss. Observational studies have suggested that the reintroduction of wolves to Yellowstone National Park initiated dramatic restoration of riparian ecosystems by releasing willows from excessive browsing by elk. Here, we present results from a decade-long experiment in Yellowstone showing that moderating browsing alone was not sufficient to restore riparian zones along small streams. Instead, restoration of willow communities depended on removing browsing and restoring hydrological conditions that prevailed before the removal of wolves. The 70-year absence of predators from the ecosystem changed the disturbance regime in a way that was not reversed by predator reintroduction. We conclude that predator restoration may not quickly repair effects of predator removal in ecosystems.

Density-dependent vulnerability of forest ecosystems to drought

USGS Publications Warehouse

Bottero, Alessandra; D'Amato, Anthony W.; Palik, Brian J.; Bradford, John B.; Fraver, Shawn; Battaglia, Mike A.; Asherin, Lance A.

2017-01-01

1. Climate models predict increasing drought intensity and frequency for many regions, which may have negative consequences for tree recruitment, growth and mortality, as well as forest ecosystem services. Furthermore, practical strategies for minimizing vulnerability to drought are limited. Tree population density, a metric of tree abundance in a given area, is a primary driver of competitive intensity among trees, which influences tree growth and mortality. Manipulating tree population density may be a mechanism for moderating drought-induced stress and growth reductions, although the relationship between tree population density and tree drought vulnerability remains poorly quantified, especially across climatic gradients.2. In this study, we examined three long-term forest ecosystem experiments in two widely distributed North American pine species, ponderosa pine Pinus ponderosa (Lawson & C. Lawson) and red pine Pinus resinosa (Aiton), to better elucidate the relationship between tree population density, growth and drought. These experiments span a broad latitude and aridity range and include tree population density treatments that have been purposefully maintained for several decades. We investigated how tree population density influenced resistance (growth during drought) and resilience (growth after drought compared to pre-drought growth) of stand-level growth during and after documented drought events.3. Our results show that relative tree population density was negatively related to drought resistance and resilience, indicating that trees growing at lower densities were less vulnerable to drought. This result was apparent in all three forest ecosystems, and was consistent across species, stand age and drought intensity.4. Synthesis and applications. Our results highlighted that managing pine forest ecosystems at low tree population density represents a promising adaptive strategy for reducing the adverse impacts of drought on forest growth in coming decades. Nonetheless, the broader applicability of our findings to other types of forest ecosystems merits additional investigation.

Experiences in multiyear combined state-parameter estimation with an ecosystem model of the North Atlantic and Arctic Oceans using the Ensemble Kalman Filter

NASA Astrophysics Data System (ADS)

Simon, Ehouarn; Samuelsen, Annette; Bertino, Laurent; Mouysset, Sandrine

2015-12-01

A sequence of one-year combined state-parameter estimation experiments has been conducted in a North Atlantic and Arctic Ocean configuration of the coupled physical-biogeochemical model HYCOM-NORWECOM over the period 2007-2010. The aim is to evaluate the ability of an ensemble-based data assimilation method to calibrate ecosystem model parameters in a pre-operational setting, namely the production of the MyOcean pilot reanalysis of the Arctic biology. For that purpose, four biological parameters (two phyto- and two zooplankton mortality rates) are estimated by assimilating weekly data such as, satellite-derived Sea Surface Temperature, along-track Sea Level Anomalies, ice concentrations and chlorophyll-a concentrations with an Ensemble Kalman Filter. The set of optimized parameters locally exhibits seasonal variations suggesting that time-dependent parameters should be used in ocean ecosystem models. A clustering analysis of the optimized parameters is performed in order to identify consistent ecosystem regions. In the north part of the domain, where the ecosystem model is the most reliable, most of them can be associated with Longhurst provinces and new provinces emerge in the Arctic Ocean. However, the clusters do not coincide anymore with the Longhurst provinces in the Tropics due to large model errors. Regarding the ecosystem state variables, the assimilation of satellite-derived chlorophyll concentration leads to significant reduction of the RMS errors in the observed variables during the first year, i.e. 2008, compared to a free run simulation. However, local filter divergences of the parameter component occur in 2009 and result in an increase in the RMS error at the time of the spring bloom.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ito, Akihiko; Inatomi, Motoko; Huntzinger, Deborah N.

The seasonal-cycle amplitude (SCA) of the atmosphere–ecosystem carbon dioxide (CO 2) exchange rate is a useful metric of the responsiveness of the terrestrial biosphere to environmental variations. It is unclear, however, what underlying mechanisms are responsible for the observed increasing trend of SCA in atmospheric CO 2 concentration. Using output data from the Multi-scale Terrestrial Model Intercomparison Project (MsTMIP), we investigated how well the SCA of atmosphere–ecosystem CO 2 exchange was simulated with 15 contemporary terrestrial ecosystem models during the period 1901–2010. Also, we made attempt to evaluate the contributions of potential mechanisms such as atmospheric CO 2, climate, land-use,more » and nitrogen deposition, through factorial experiments using different combinations of forcing data. Under contemporary conditions, the simulated global-scale SCA of the cumulative net ecosystem carbon flux of most models was comparable in magnitude with the SCA of atmospheric CO 2 concentrations. Results from factorial simulation experiments showed that elevated atmospheric CO 2 exerted a strong influence on the seasonality amplification. When the model considered not only climate change but also land-use and atmospheric CO 2 changes, the majority of the models showed amplification trends of the SCAs of photosynthesis, respiration, and net ecosystem production (+0.19 % to +0.50 % yr -1). In the case of land-use change, it was difficult to separate the contribution of agricultural management to SCA because of inadequacies in both the data and models. The simulated amplification of SCA was approximately consistent with the observational evidence of the SCA in atmospheric CO 2 concentrations. Large inter-model differences remained, however, in the simulated global tendencies and spatial patterns of CO 2 exchanges. Further studies are required to identify a consistent explanation for the simulated and observed amplification trends, including their underlying mechanisms. Nevertheless, this study implied that monitoring of ecosystem seasonality would provide useful insights concerning ecosystem dynamics.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ito, Akihiko; Inatomi, Motoko; Huntzinger, Deborah N.

The seasonal-cycle amplitude (SCA) of the atmosphere–ecosystem carbon dioxide (CO 2) exchange rate is a useful metric of the responsiveness of the terrestrial biosphere to environmental variations. It is unclear, however, what underlying mechanisms are responsible for the observed increasing trend of SCA in atmospheric CO 2 concentration. Using output data from the Multi-scale Terrestrial Model Intercomparison Project (MsTMIP), we investigated how well the SCA of atmosphere–ecosystem CO 2 exchange was simulated with 15 contemporary terrestrial ecosystem models during the period 1901–2010. Also, we made attempt to evaluate the contributions of potential mechanisms such as atmospheric CO 2, climate, land-use,more » and nitrogen deposition, through factorial experiments using different combinations of forcing data. Under contemporary conditions, the simulated global-scale SCA of the cumulative net ecosystem carbon flux of most models was comparable in magnitude with the SCA of atmospheric CO 2 concentrations. Results from factorial simulation experiments showed that elevated atmospheric CO 2 exerted a strong influence on the seasonality amplification. When the model considered not only climate change but also land-use and atmospheric CO 2 changes, the majority of the models showed amplification trends of the SCAs of photosynthesis, respiration, and net ecosystem production (+0.19 % to +0.50 % yr –1). In the case of land-use change, it was difficult to separate the contribution of agricultural management to SCA because of inadequacies in both the data and models. The simulated amplification of SCA was approximately consistent with the observational evidence of the SCA in atmospheric CO 2 concentrations. Large inter-model differences remained, however, in the simulated global tendencies and spatial patterns of CO 2 exchanges. Further studies are required to identify a consistent explanation for the simulated and observed amplification trends, including their underlying mechanisms. Furthermore, this study implied that monitoring of ecosystem seasonality would provide useful insights concerning ecosystem dynamics.« less

Thermocline deepening boosts ecosystem metabolism: evidence from a large-scale lake enclosure experiment simulating a summer storm.

PubMed

Giling, Darren P; Nejstgaard, Jens C; Berger, Stella A; Grossart, Hans-Peter; Kirillin, Georgiy; Penske, Armin; Lentz, Maren; Casper, Peter; Sareyka, Jörg; Gessner, Mark O

2017-04-01

Extreme weather events can pervasively influence ecosystems. Observations in lakes indicate that severe storms in particular can have pronounced ecosystem-scale consequences, but the underlying mechanisms have not been rigorously assessed in experiments. One major effect of storms on lakes is the redistribution of mineral resources and plankton communities as a result of abrupt thermocline deepening. We aimed at elucidating the importance of this effect by mimicking in replicated large enclosures (each 9 m in diameter, ca. 20 m deep, ca. 1300 m 3 in volume) a mixing event caused by a severe natural storm that was previously observed in a deep clear-water lake. Metabolic rates were derived from diel changes in vertical profiles of dissolved oxygen concentrations using a Bayesian modelling approach, based on high-frequency measurements. Experimental thermocline deepening stimulated daily gross primary production (GPP) in surface waters by an average of 63% for >4 weeks even though thermal stratification re-established within 5 days. Ecosystem respiration (ER) was tightly coupled to GPP, exceeding that in control enclosures by 53% over the same period. As GPP responded more strongly than ER, net ecosystem productivity (NEP) of the entire water column was also increased. These protracted increases in ecosystem metabolism and autotrophy were driven by a proliferation of inedible filamentous cyanobacteria released from light and nutrient limitation after they were entrained from below the thermocline into the surface water. Thus, thermocline deepening by a single severe storm can induce prolonged responses of lake ecosystem metabolism independent of other storm-induced effects, such as inputs of terrestrial materials by increased catchment run-off. This highlights that future shifts in frequency, severity or timing of storms are an important component of climate change, whose impacts on lake thermal structure will superimpose upon climate trends to influence algal dynamics and organic matter cycling in clear-water lakes. © 2016 John Wiley & Sons Ltd.

Decadal trends in the seasonal-cycle amplitude of terrestrial CO 2 exchange resulting from the ensemble of terrestrial biosphere models

DOE PAGES

Ito, Akihiko; Inatomi, Motoko; Huntzinger, Deborah N.; ...

2016-05-12

The seasonal-cycle amplitude (SCA) of the atmosphere–ecosystem carbon dioxide (CO 2) exchange rate is a useful metric of the responsiveness of the terrestrial biosphere to environmental variations. It is unclear, however, what underlying mechanisms are responsible for the observed increasing trend of SCA in atmospheric CO 2 concentration. Using output data from the Multi-scale Terrestrial Model Intercomparison Project (MsTMIP), we investigated how well the SCA of atmosphere–ecosystem CO 2 exchange was simulated with 15 contemporary terrestrial ecosystem models during the period 1901–2010. Also, we made attempt to evaluate the contributions of potential mechanisms such as atmospheric CO 2, climate, land-use,more » and nitrogen deposition, through factorial experiments using different combinations of forcing data. Under contemporary conditions, the simulated global-scale SCA of the cumulative net ecosystem carbon flux of most models was comparable in magnitude with the SCA of atmospheric CO 2 concentrations. Results from factorial simulation experiments showed that elevated atmospheric CO 2 exerted a strong influence on the seasonality amplification. When the model considered not only climate change but also land-use and atmospheric CO 2 changes, the majority of the models showed amplification trends of the SCAs of photosynthesis, respiration, and net ecosystem production (+0.19 % to +0.50 % yr –1). In the case of land-use change, it was difficult to separate the contribution of agricultural management to SCA because of inadequacies in both the data and models. The simulated amplification of SCA was approximately consistent with the observational evidence of the SCA in atmospheric CO 2 concentrations. Large inter-model differences remained, however, in the simulated global tendencies and spatial patterns of CO 2 exchanges. Further studies are required to identify a consistent explanation for the simulated and observed amplification trends, including their underlying mechanisms. Furthermore, this study implied that monitoring of ecosystem seasonality would provide useful insights concerning ecosystem dynamics.« less

Quantification of Carbon and Phosphorus Co-Limitation in Bacterioplankton: New Insights on an Old Topic

PubMed Central

Dorado-García, Irene; Medina-Sánchez, Juan Manuel; Herrera, Guillermo; Cabrerizo, Marco J.; Carrillo, Presentación

2014-01-01

Because the nature of the main resource that limits bacterioplankton (e.g. organic carbon [C] or phosphorus [P]) has biogeochemical implications concerning organic C accumulation in freshwater ecosystems, empirical knowledge is needed concerning how bacteria respond to these two resources, available alone or together. We performed field experiments of resource manipulation (2×2 factorial design, with the addition of C, P, or both combined) in two Mediterranean freshwater ecosystems with contrasting trophic states (oligotrophy vs. eutrophy) and trophic natures (autotrophy vs. heterotrophy, measured as gross primary production:respiration ratio). Overall, the two resources synergistically co-limited bacterioplankton, i.e. the magnitude of the response of bacterial production and abundance to the two resources combined was higher than the additive response in both ecosystems. However, bacteria also responded positively to single P and C additions in the eutrophic ecosystem, but not to single C in the oligotrophic one, consistent with the value of the ratio between bacterial C demand and algal C supply. Accordingly, the trophic nature rather than the trophic state of the ecosystems proves to be a key feature determining the expected types of resource co-limitation of bacteria, as summarized in a proposed theoretical framework. The actual types of co-limitation shifted over time and partially deviated (a lesser degree of synergism) from the theoretical expectations, particularly in the eutrophic ecosystem. These deviations may be explained by extrinsic ecological forces to physiological limitations of bacteria, such as predation, whose role in our experiments is supported by the relationship between the dynamics of bacteria and bacterivores tested by SEMs (structural equation models). Our study, in line with the increasingly recognized role of freshwater ecosystems in the global C cycle, suggests that further attention should be focussed on the biotic interactions that modulate resource co-limitation of bacteria. PMID:24918445

Are Seagrass effective Sentinels of Ecosystem Health in Port Phillip Bay, Australia?

NASA Astrophysics Data System (ADS)

Lee, R. S.; Cook, P. L. M.; Jenkins, G.; Nayar, S.; Hirst, A.; Keough, M. J.; Smith, T.; Ferguson, A.; Gay, J.; Longmore, A. R.; Macreadie, P.; Sherman, C.; Ross, J.; York, P.

2016-02-01

Seagrasses are an important part of many coastal systems, but are also under threat in many areas, as a result of a wide range of human activities, including habitat loss and changes to water quality. Due to these sensitivities seagrass are often selected as sentinels of change for coastal marine ecosystems, but could these sensitivities be too complex and varied to provide a clear or reliable measure of change? A recent three year study focused on the resilience of Zostera seagrasses in Port Phillip Bay, Southern Australia, where these ecosystem "engineers", have a dramatic influence on biodiversity and ecosystem function. This large temperate embayment experiences extreme climatic variability, significant loading from urbanized catchments and inflows from the largest sewage treatment facility in Australia, making it a challenging case study for assessing seagrass as a suitable ecosystem metric. Studies on the influence of nutrients, light and sediments using modelling, chemical analyses and field experiments assessed characteristics of Zostera habitat within the bay. Nutrients could be obtained directly in dissolved form from the water column, or sediment, or as atmospheric nitrogen fixed by bacteria associated with the root/rhizome system. Isotopic nutrients were traced to a variety of sources including river inflows, sewage discharges, groundwater, the open ocean, the atmosphere and indirectly via phytoplankton and detritus. Broad-scale seagrass coverage is often depth limited by light, however for regions of significant wave exposure deeper beds existed adjacent to less favorable shallows. Ephemeral beds in more exposed regions showed the greatest potential for responding to change. For these beds, resilience was dependent on bed architecture, connectivity to indirect nutrient sources, and genetic interactions with seagrass communities around the bay. While observed changes in seagrass cover may be a symptomatic trigger of ecosystem health, much as high blood pressure is to the human body, this study has shown that an understanding of the relative threats, system connectivity and co-dependencies of the more vulnerable communities can provide the most accurate account of ecosystem health.

The Swedish Research Infrastructure for Ecosystem Science - SITES

NASA Astrophysics Data System (ADS)

Lindroth, A.; Ahlström, M.; Augner, M.; Erefur, C.; Jansson, G.; Steen Jensen, E.; Klemedtsson, L.; Langenheder, S.; Rosqvist, G. N.; Viklund, J.

2017-12-01

The vision of SITES is to promote long-term field-based ecosystem research at a world class level by offering an infrastructure with excellent technical and scientific support and services attracting both national and international researchers. In addition, SITES will make data freely and easily available through an advanced data portal which will add value to the research. During the first funding period, three innovative joint integrating facilities were established through a researcher-driven procedure: SITES Water, SITES Spectral, and SITES AquaNet. These new facilities make it possible to study terrestrial and limnic ecosystem processes across a range of ecosystem types and climatic gradients, with common protocols and similar equipment. In addition, user-driven development at the nine individual stations has resulted in e.g. design of a long-term agricultural systems experiment, and installation of weather stations, flux systems, etc. at various stations. SITES, with its integrative approach and broad coverage of climate and ecosystem types across Sweden, constitutes an excellent platform for state-of-the-art research projects. SITES' support the development of: A better understanding of the way in which key ecosystems function and interact with each other at the landscape level and with the climate system in terms of mass and energy exchanges. A better understanding of the role of different organisms in controlling different processes and ultimately the functioning of ecosystems. New strategies for forest management to better meet the many and varied requirements from nature conservation, climate and wood, fibre, and energy supply points of view. Agricultural systems that better utilize resources and minimize adverse impacts on the environment. Collaboration with other similar infrastructures and networks is a high priority for SITES. This will enable us to make use of each others' experiences, harmonize metadata for easier exchange of data, and support each other to widen the user community.

Conservation lessons from large-mammal manipulations in East African savannas: the KLEE, UHURU, and GLADE experiments.

PubMed

Goheen, Jacob R; Augustine, David J; Veblen, Kari E; Kimuyu, Duncan M; Palmer, Todd M; Porensky, Lauren M; Pringle, Robert M; Ratnam, Jayashree; Riginos, Corinna; Sankaran, Mahesh; Ford, Adam T; Hassan, Abdikadir A; Jakopak, Rhiannon; Kartzinel, Tyler R; Kurukura, Samson; Louthan, Allison M; Odadi, Wilfred O; Otieno, Tobias O; Wambua, Alois M; Young, Hillary S; Young, Truman P

2018-05-11

African savannas support an iconic fauna, but they are undergoing large-scale population declines and extinctions of large (>5 kg) mammals. Long-term, controlled, replicated experiments that explore the consequences of this defaunation (and its replacement with livestock) are rare. The Mpala Research Centre in Laikipia County, Kenya, hosts three such experiments, spanning two adjacent ecosystems and environmental gradients within them: the Kenya Long-Term Exclosure Experiment (KLEE; since 1995), the Glade Legacies and Defaunation Experiment (GLADE; since 1999), and the Ungulate Herbivory Under Rainfall Uncertainty experiment (UHURU; since 2008). Common themes unifying these experiments are (1) evidence of profound effects of large mammalian herbivores on herbaceous and woody plant communities; (2) competition and compensation across herbivore guilds, including rodents; and (3) trophic cascades and other indirect effects. We synthesize findings from the past two decades to highlight generalities and idiosyncrasies among these experiments, and highlight six lessons that we believe are pertinent for conservation. The removal of large mammalian herbivores has dramatic effects on the ecology of these ecosystems; their ability to rebound from these changes (after possible refaunation) remains unexplored. © 2018 New York Academy of Sciences.

Does an understanding of ecosystems responses to rainfall pulses improve predictions of responses of drylands to climate change?

USDA-ARS?s Scientific Manuscript database

Drylands will experience more intense and frequent droughts and floods. Ten-year field experiments manipulating the amount and variability of precipitation suggest that we cannot predict responses of drylands to climate change based on pulse experimentation. Long-term drought experiments showed no e...

Seed size- and density-related hidden treatments in common biodiversity experiments

Treesearch

Qinfeng Guo

2011-01-01

With a few exceptions, most well-known field biodiversity experiments on ecosystem functioning have been conducted in plant communities (especially grasslands) in which different numbers of species are planted as treatments. In these experiments, investigators have either kept the total seed weight or seed number constant across treatment plots. However, although in...

Drought and tree mortality in tropical rainforest: understanding and differentiating functional responses

NASA Astrophysics Data System (ADS)

Meir, P.; Rowland, L.; da Costa, A. C. L.; Mencuccini, M.; Oliveira, A.; Binks, O.; Christoffersen, B. O.; Eliane, M.; Vasconcelos, S.; Kruijt, B.; Ferreira, L.

2014-12-01

Our understanding of how forests respond to drought is especially constrained with respect to widespread tree mortality events. This limitation is particularly clear for tropical forests, despite the risk of drought to these ecosystems during the coming decades. We present new findings from the only current long-term 'ecosystem-scale' (1 ha) rainfall manipulation experiment in tropical rainforest, the Esecaflor experiment at Caxiuana National Forest, Para State, Brazil. Throughfall has been partially excluded from experimental forest at the Esecaflor experiment for more than a decade. We have previously demonstrated a capacity to model short-term physiological responses well, but longer term physiology and ecological dynamics remain challenging to understand and represent. In particular, high mortality and increased autotrophic respiration following extended drought are poorly understood phenomena, and their interaction with hydraulic responses and limitations needs to be characterised. We present initial data that for the first time combine carbon use and hydraulic metrics, comparing drought-vulnerable and non-vulnerable species that have experienced extended soil moisture deficit, as imposed in the experiment, also considering the response in soil respiration. We also discuss how these findings can be used to develop future empirical and modelling studies aimed at improving our capacity to predict the effects of drought on tropical forest ecosystems in Amazonia and in other tropical forest regions where species characteristics and environmental constraints may influence both short and long-term responses to drought.

Research on red tide occurrences using enclosed experimental ecosystems in west Xiamen Harbor, China—Relationship between various factors and red tide occurrences

NASA Astrophysics Data System (ADS)

Lin, Yu; Harrison, P. J.

2000-06-01

A series of enclosed ecosystem experiments were conducted in a land-based tank near the seaside of West Xiamen Harbor. The results of experiments conducted in different seasons and years showed a repeatable phytoplankton succession. In this relatively stable ecosystem with added nutrients and trace metals, diatoms dominated initially, dinoflagellates dominated in the later stage, and dinoflagellate red tides eventually occurred. Vitamin B12 enrichment may speed up this succession process. Stirring the water column could stop this process. Soluble Mn at a level of 3 4 μg/L in seawater, which also is the existing concentration of soluble Mn in Xiamen Harbor seawater, is sufficient for the multiplication of algae and occurrence of red tide. The present study showed that excessive soluble Mn in Xiamen Harbor cannot cause red tide, and that Fe was one of the important factors causing diatiom red tide in this present study.

Few multi-year precipitation-reduction experiments find a shift in the productivity-precipitation relationship

DOE PAGES

Estiarte, Marc; Vicca, Sara; Penuelas, Josep; ...

2016-04-06

Well-defined productivity–precipitation relationships of ecosystems are needed as benchmarks for the validation of land models used for future projections. The productivity–precipitation relationship may be studied in two ways: the spatial approach relates differences in productivity to those in precipitation among sites along a precipitation gradient (the spatial fit, with a steeper slope); the temporal approach relates interannual productivity changes to variation in precipitation within sites (the temporal fits, with flatter slopes). Precipitation–reduction experiments in natural ecosystems represent a complement to the fits, because they can reduce precipitation below the natural range and are thus well suited to study potential effectsmore » of climate drying. Here, we analyse the effects of dry treatments in eleven multiyear precipitation–manipulation experiments, focusing on changes in the temporal fit. We expected that structural changes in the dry treatments would occur in some experiments, thereby reducing the intercept of the temporal fit and displacing the productivity–precipitation relationship downward the spatial fit. Seventy two percent of expiriments showed that dry treatments did not alter the temporal fit. This implies that current temporal fits are to be preferred over the spatial fit to benchmark land-model projections of productivity under future climate within the precipitation ranges covered by the experiments. Moreover, in two experiments, the intercept of the temporal fit unexpectedly increased due to mechanisms that reduced either water loss or nutrient loss. The expected decrease of the intercept was observed in only one experiment, and only when distinguishing between the late and the early phases of the experiment. This implies that we currently do not know at which precipitation–reduction level or at which experimental duration structural changes will start to alter ecosystem productivity. Our study highlights the need for experiments with multiple, including more extreme, dry treatments, to identify the precipitation boundaries within which the current temporal fits remain valid.« less

Few multi-year precipitation-reduction experiments find a shift in the productivity-precipitation relationship

DOE Office of Scientific and Technical Information (OSTI.GOV)

Estiarte, Marc; Vicca, Sara; Penuelas, Josep

Well-defined productivity–precipitation relationships of ecosystems are needed as benchmarks for the validation of land models used for future projections. The productivity–precipitation relationship may be studied in two ways: the spatial approach relates differences in productivity to those in precipitation among sites along a precipitation gradient (the spatial fit, with a steeper slope); the temporal approach relates interannual productivity changes to variation in precipitation within sites (the temporal fits, with flatter slopes). Precipitation–reduction experiments in natural ecosystems represent a complement to the fits, because they can reduce precipitation below the natural range and are thus well suited to study potential effectsmore » of climate drying. Here, we analyse the effects of dry treatments in eleven multiyear precipitation–manipulation experiments, focusing on changes in the temporal fit. We expected that structural changes in the dry treatments would occur in some experiments, thereby reducing the intercept of the temporal fit and displacing the productivity–precipitation relationship downward the spatial fit. Seventy two percent of expiriments showed that dry treatments did not alter the temporal fit. This implies that current temporal fits are to be preferred over the spatial fit to benchmark land-model projections of productivity under future climate within the precipitation ranges covered by the experiments. Moreover, in two experiments, the intercept of the temporal fit unexpectedly increased due to mechanisms that reduced either water loss or nutrient loss. The expected decrease of the intercept was observed in only one experiment, and only when distinguishing between the late and the early phases of the experiment. This implies that we currently do not know at which precipitation–reduction level or at which experimental duration structural changes will start to alter ecosystem productivity. Our study highlights the need for experiments with multiple, including more extreme, dry treatments, to identify the precipitation boundaries within which the current temporal fits remain valid.« less

Impacts of biodiversity loss on ocean ecosystem services.

PubMed

Worm, Boris; Barbier, Edward B; Beaumont, Nicola; Duffy, J Emmett; Folke, Carl; Halpern, Benjamin S; Jackson, Jeremy B C; Lotze, Heike K; Micheli, Fiorenza; Palumbi, Stephen R; Sala, Enric; Selkoe, Kimberley A; Stachowicz, John J; Watson, Reg

2006-11-03

Human-dominated marine ecosystems are experiencing accelerating loss of populations and species, with largely unknown consequences. We analyzed local experiments, long-term regional time series, and global fisheries data to test how biodiversity loss affects marine ecosystem services across temporal and spatial scales. Overall, rates of resource collapse increased and recovery potential, stability, and water quality decreased exponentially with declining diversity. Restoration of biodiversity, in contrast, increased productivity fourfold and decreased variability by 21%, on average. We conclude that marine biodiversity loss is increasingly impairing the ocean's capacity to provide food, maintain water quality, and recover from perturbations. Yet available data suggest that at this point, these trends are still reversible.

Hexabromocyclododecane affects benthic-pelagic coupling in an experimental ecosystem.

PubMed

Bradshaw, Clare; Näslund, Johan; Hansen, Joakim; Kozlowsky-Suzuki, Betina; Sundström, Bo; Gustafsson, Kerstin

2015-11-01

Hexabromocyclododecane (HBCDD) is an additive brominated flame retardant and a recognized PBT chemical. However, little is known about its effects on coastal species, and even less on ecosystem effects. We investigated the dose-response effects of HBCDD over 8 months in 1000 L experimental mesocosms assembled from coastal Baltic Sea ecosystem components. HBCDD was added via spiked plankton material and a range of structural and functional endpoints were measured during the experiment. Increasing HBCDD concentration decreased the biomass of large Macoma balthica, resulting in a decreased recirculation of nutrients to the water. Changes in plankton communities were also observed, either due to direct toxic HBCDD effects or indirect via changes in benthic-pelagic coupling of nutrients. Such complex ecosystem responses can only be quantified and understood by using realistic experimental set-ups, and including knowledge of system-specific ecological interactions. This is the first study of HBCDD effects on ecosystem level. Copyright © 2015 Elsevier Ltd. All rights reserved.

Combined effects of agrochemicals and ecosystem services on crop yield across Europe.

PubMed

Gagic, Vesna; Kleijn, David; Báldi, András; Boros, Gergely; Jørgensen, Helene Bracht; Elek, Zoltán; Garratt, Michael P D; de Groot, G Arjen; Hedlund, Katarina; Kovács-Hostyánszki, Anikó; Marini, Lorenzo; Martin, Emily; Pevere, Ines; Potts, Simon G; Redlich, Sarah; Senapathi, Deepa; Steffan-Dewenter, Ingolf; Świtek, Stanislaw; Smith, Henrik G; Takács, Viktória; Tryjanowski, Piotr; van der Putten, Wim H; van Gils, Stijn; Bommarco, Riccardo

2017-11-01

Simultaneously enhancing ecosystem services provided by biodiversity below and above ground is recommended to reduce dependence on chemical pesticides and mineral fertilisers in agriculture. However, consequences for crop yield have been poorly evaluated. Above ground, increased landscape complexity is assumed to enhance biological pest control, whereas below ground, soil organic carbon is a proxy for several yield-supporting services. In a field experiment replicated in 114 fields across Europe, we found that fertilisation had the strongest positive effect on yield, but hindered simultaneous harnessing of below- and above-ground ecosystem services. We furthermore show that enhancing natural enemies and pest control through increasing landscape complexity can prove disappointing in fields with low soil services or in intensively cropped regions. Thus, understanding ecological interdependences between land use, ecosystem services and yield is necessary to promote more environmentally friendly farming by identifying situations where ecosystem services are maximised and agrochemical inputs can be reduced. © 2017 John Wiley & Sons Ltd/CNRS.

Assessing ecosystem response to multiple disturbances and climate change in South Africa using ground- and satellite-based measurements and model

NASA Astrophysics Data System (ADS)

Kutsch, W. L.; Falge, E. M.; Brümmer, C.; Mukwashi, K.; Schmullius, C.; Hüttich, C.; Odipo, V.; Scholes, R. J.; Mudau, A.; Midgley, G.; Stevens, N.; Hickler, T.; Scheiter, S.; Martens, C.; Twine, W.; Iiyambo, T.; Bradshaw, K.; Lück, W.; Lenfers, U.; Thiel-Clemen, T.; du Toit, J.

2015-12-01

Sub-Saharan Africa currently experiences rapidly growing human population, intrinsically tied to substantial changes in land use on shrubland, savanna and mixed woodland ecosystems due to over-exploitation. Significant conversions driving degradation, affecting fire frequency and water availability, and fueling climate change are expected to increase in the immediate future. However, measured data of greenhouse gas emissions as affected by land use change are scarce to entirely lacking from this region. The project 'Adaptive Resilience of Southern African Ecosystems' (ARS AfricaE) conducts research and develops scenarios of ecosystem development under climate change, for management support in conservation or for planning rural area development. This will be achieved by (1) creation of a network of research clusters (paired sites with natural and altered vegetation) along an aridity gradient in South Africa for ground-based micrometeorological in-situ measurements of energy and matter fluxes, (2) linking biogeochemical functions with ecosystem structure, and eco-physiological properties, (3) description of ecosystem disturbance (and recovery) in terms of ecosystem function such as carbon balance components and water use efficiency, (4) set-up of individual-based models to predict ecosystem dynamics under (post) disturbance managements, (5) combination with long-term landscape dynamic information derived from remote sensing and aerial photography, and (6) development of sustainable management strategies for disturbed ecosystems and land use change. Emphasis is given on validation (by a suite of field measurements) of estimates obtained from eddy covariance, model approaches and satellite derivations.

Fungal symbiosis and precipitation alter traits and dune building by the ecosystem engineer, Ammophila breviligulata.

PubMed

Emery, Sarah M; Bell-Dereske, Lukas; Rudgers, Jennifer A

2015-04-01

Ecosystem engineer species influence their community and ecosystem by creating or altering the physical structure of habitats. The function of ecosystem engineers is variable and can depend on both abiotic and biotic factors. Here we make use of a primary successional system to evaluate the direct and interactive effects of climate change (precipitation) and fungal endophyte symbiosis on population traits and ecosystem function of the ecosystem engineering grass species, Ammophila breviligulata. We manipulated endophyte presence in A. breviligulata in combination with rain-out shelters and rainfall additions in a factorial field experiment established in 2010 on Lake Michigan sand dunes. We monitored plant traits, survival, growth, and sexual reproduction of A. breviligulata from 2010-2013, and quantified ecosystem engineering as the sand accumulation rate. Presence of the endophyte in A. breviligulata increased vegetative growth by up to 19%, and reduced sexual reproduction by up to 46% across all precipitation treatments. Precipitation was a less significant factor than endophyte colonization for A. breviligulata growth. Reduced precipitation increased average leaf number per tiller but had no other effects on plant traits. Changes in A. breviligulata traits corresponded to increases in sand accumulation in plots with the endophyte as well as in plots with reduced precipitation. Sand accumulation is a key ecosystem function in these primary successional habitats, and so microbial symbiosis in this ecosystem engineer could lead to direct effects on the value of these dune habitats for humans.

Mitigation for one & all: An integrated framework for mitigation of development impacts on biodiversity and ecosystem services

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tallis, Heather, E-mail: htallis@tnc.org; Kennedy, Christina M., E-mail: ckennedy@tnc.org; Ruckelshaus, Mary

Emerging development policies and lending standards call for consideration of ecosystem services when mitigating impacts from development, yet little guidance exists to inform this process. Here we propose a comprehensive framework for advancing both biodiversity and ecosystem service mitigation. We have clarified a means for choosing representative ecosystem service targets alongside biodiversity targets, identified servicesheds as a useful spatial unit for assessing ecosystem service avoidance, impact, and offset options, and discuss methods for consistent calculation of biodiversity and ecosystem service mitigation ratios. We emphasize the need to move away from area- and habitat-based assessment methods for both biodiversity and ecosystemmore » services towards functional assessments at landscape or seascape scales. Such comprehensive assessments more accurately reflect cumulative impacts and variation in environmental quality, social needs and value preferences. The integrated framework builds on the experience of biodiversity mitigation while addressing the unique opportunities and challenges presented by ecosystem service mitigation. These advances contribute to growing potential for economic development planning and execution that will minimize impacts on nature and maximize human wellbeing. - Highlights: • This is the first framework for biodiversity and ecosystem service mitigation. • Functional, landscape scale assessments are ideal for avoidance and offsets. • Servicesheds define the appropriate spatial extent for ecosystem service mitigation. • Mitigation ratios should be calculated consistently and based on standard factors. • Our framework meets the needs of integrated mitigation assessment requirements.« less

Functional Role of Native and Invasive Filter-Feeders, and the Effect of Parasites: Learning from Hypersaline Ecosystems.

PubMed

Sánchez, Marta I; Paredes, Irene; Lebouvier, Marion; Green, Andy J

2016-01-01

Filter-feeding organisms are often keystone species with a major influence on the dynamics of aquatic ecosystems. Studies of filtering rates in such taxa are therefore vital in order to understand ecosystem functioning and the impact of natural and anthropogenic stressors such as parasites, climate warming and invasive species. Brine shrimps Artemia spp. are the dominant grazers in hypersaline systems and are a good example of such keystone taxa. Hypersaline ecosystems are relatively simplified environments compared with much more complex freshwater and marine ecosystems, making them suitable model systems to address these questions. The aim of this study was to compare feeding rates at different salinities and temperatures between clonal A. parthenogenetica (native to Eurasia and Africa) and the invasive American brine shrimp A. franciscana, which is excluding native Artemia from many localities. We considered how differences observed in laboratory experiments upscale at the ecosystem level across both spatial and temporal scales (as indicated by chlorophyll-a concentration and turbidity). In laboratory experiments, feeding rates increased at higher temperatures and salinities in both Artemia species and sexes, whilst A. franciscana consistently fed at higher rates. A field study of temporal dynamics revealed significantly higher concentrations of chlorophyll-a in sites occupied by A. parthenogenetica, supporting our experimental findings. Artemia parthenogenetica density and biomass were negatively correlated with chlorophyll-a concentration at the spatial scale. We also tested the effect of cestode parasites, which are highly prevalent in native Artemia but much rarer in the invasive species. The cestodes Flamingolepis liguloides and Anomotaenia tringae decreased feeding rates in native Artemia, whilst Confluaria podicipina had no significant effect. Total parasite prevalence was positively correlated with turbidity. Overall, parasites are likely to reduce feeding rates in the field, and their negative impact on host fecundity is likely to exacerbate the difference between grazing rates of native and alien Artemia populations at the ecosystem level. The results of this study provide evidence for the first time that the replacement of native Artemia by A. franciscana may have major consequences for the functioning of hypersaline ecosystems. The strong effect of parasites on feeding rate underlines the importance of taking parasites into account in order to improve our understanding of the functioning of aquatic ecosystems.

The ecological risks of genetically engineered organisms

NASA Astrophysics Data System (ADS)

Wolfenbarger, Lareesa

2001-03-01

Highly publicized studies have suggested environmental risks of releasing genetically engineered organisms (GEOs) and have renewed concerns over the evaluation and regulation of these products in domestic and international arenas. I present an overview of the risks of GEOs and the available evidence addressing these and discuss the challenges for risk assessment. Main categories of risk include non-target effects from GEOs, emergence of new viral diseases, and the spread of invasive (weedy) characteristics. Studies have detected non-target effects in some cases but not all; however, much less information exists on other risks, in part due to a lack of conceptual knowledge. For example, general models for predicting invasiveness are not well developed for any introduced organism. The risks of GEOs appear comparable to those for any introduced species or organism, but the magnitude of the risk or the pathway of exposure to the risk can differ among introduced organisms. Therefore, assessing the risks requires a case-by-case analysis so that any differences can be identified. Challenges to assessing risks to valued ecosystems include variability in effects and ecosystem complexity. Ecosystems are a dynamic and complex network of biological and physical interactions. Introducing a new biological entity, such as a GEO, may potentially alter any of these interactions, but evaluating all of these is unrealistic. Effects on a valued ecosystem could vary greatly depending on the geographical location of the experimental site, the GEO used, the plot size of the experiment (scaling effects), and the biological and physical parameters used in the experiment. Experiments that address these sources of variability will provide the most useful information for risk assessments.

Reactivity and mobility of new and old mercury deposition in a boreal forest ecosystem during the first year of the METAALICUS study

USGS Publications Warehouse

Hintelmann, H.; Harris, R.; Heyes, A.; Hurley, J.P.; Kelly, C.A.; Krabbenhoft, D.P.; Lindberg, S.; Rudd, J.W.M.; Scott, K.J.; St. Louis, V.L.

2002-01-01

The METAALICUS (Mercury Experiment To Assess Atmospheric Loading In Canada and the US) project is a whole ecosystem experiment designed to study the activity, mobility, and availability of atmospherically deposited mercury. To investigate the dynamics of mercury newly deposited onto a terrestrial ecosystem, an enriched stable isotope of mercury (202Hg) was sprayed onto a Boreal forest subcatchment in an experiment that allowed us, for the first time, to monitor the fate of "new" mercury in deposition and to distinguish it from native mercury historically stored in the ecosystem. Newly deposited mercury was more reactive than the native mercury with respect to volatilization and methylation pathways. Mobility through runoff was very low and strongly decreased with time because of a rapid equilibration with the large native pool of "bound" mercury. Over one season, only ???8% of the added 202Hg volatilized to the atmosphere and less than 1% appeared in runoff. Within a few months, approximately 66% of the applied 202Hg remained associated with above ground vegetation, with the rest being incorporated into soils. The fraction of 202Hg bound to vegetation was much higher than seen for native Hg (<5% vegetation), suggesting that atmospherically derived mercury enters the soil pool with a time delay, after plants senesce and decompose. The initial mobility of mercury received through small rain events or dry deposition decreased markedly in a relatively short time period, suggesting that mercury levels in terrestrial runoff may respond slowly to changes in mercury deposition rates.

Meta-analysis of high-latitude nitrogen-addition and warming studies implies ecological mechanisms overlooked by land models

DOE PAGES

Bouskill, N. J.; Riley, W. J.; Tang, J. Y.

2014-12-11

Accurate representation of ecosystem processes in land models is crucial for reducing predictive uncertainty in energy and greenhouse gas feedbacks with the climate. Here we describe an observational and modeling meta-analysis approach to benchmark land models, and apply the method to the land model CLM4.5 with two versions of belowground biogeochemistry. We focused our analysis on the aboveground and belowground responses to warming and nitrogen addition in high-latitude ecosystems, and identified absent or poorly parameterized mechanisms in CLM4.5. While the two model versions predicted similar soil carbon stock trajectories following both warming and nitrogen addition, other predicted variables (e.g., belowgroundmore » respiration) differed from observations in both magnitude and direction, indicating that CLM4.5 has inadequate underlying mechanisms for representing high-latitude ecosystems. On the basis of observational synthesis, we attribute the model–observation differences to missing representations of microbial dynamics, aboveground and belowground coupling, and nutrient cycling, and we use the observational meta-analysis to discuss potential approaches to improving the current models. However, we also urge caution concerning the selection of data sets and experiments for meta-analysis. For example, the concentrations of nitrogen applied in the synthesized field experiments (average = 72 kg ha -1 yr -1) are many times higher than projected soil nitrogen concentrations (from nitrogen deposition and release during mineralization), which precludes a rigorous evaluation of the model responses to likely nitrogen perturbations. Overall, we demonstrate that elucidating ecological mechanisms via meta-analysis can identify deficiencies in ecosystem models and empirical experiments.« less

Biodiversity-ecosystem functioning relationships in a long-term non-weeded field experiment.

PubMed

Veen, Ciska G F; van der Putten, Wim H; Bezemer, T Martijn

2018-05-30

Many grassland biodiversity experiments show a positive relationship between biodiversity and ecosystem functioning, however, in most these experiments plant communities are established by sowing and natural colonization is prevented by selective weeding of non-sown species. During ecosystem restoration, for example on abandoned fields, plant communities start on bare soil, and diversity is often manipulated in a single sowing event. How such initial plant diversity manipulations influence plant biodiversity development and ecosystem functioning is not well understood. We examined how relationships between taxonomic and functional diversity, biomass production and stability develop over 16 years in non-weeded plots sown with 15 species, 4 species, or that were not sown. We found that sown plant communities become functionally similar to unsown, naturally colonized plant communities. However, initial sowing treatments had long-lasting effects on species composition and taxonomic diversity. We found only few relationships between biomass production, or stability in biomass production, and functional or taxonomic diversity, and the ones we observed were negative. In addition, the cover of dominant plant species was positively related to biomass production and stability. We conclude that effects of introducing plant species at the start of secondary succession can persist for a long time, and that in secondary succession communities with natural plant species dynamics diversity-functioning relationships can be weak or negative. Moreover, our findings indicate that in systems where natural colonization of species is allowed effects of plant dominance may underlie diversity-functioning relationships. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Meta-analysis of high-latitude nitrogen-addition and warming studies implies ecological mechanisms overlooked by land models

NASA Astrophysics Data System (ADS)

Bouskill, N. J.; Riley, W. J.; Tang, J. Y.

2014-12-01

Accurate representation of ecosystem processes in land models is crucial for reducing predictive uncertainty in energy and greenhouse gas feedbacks with the climate. Here we describe an observational and modeling meta-analysis approach to benchmark land models, and apply the method to the land model CLM4.5 with two versions of belowground biogeochemistry. We focused our analysis on the aboveground and belowground responses to warming and nitrogen addition in high-latitude ecosystems, and identified absent or poorly parameterized mechanisms in CLM4.5. While the two model versions predicted similar soil carbon stock trajectories following both warming and nitrogen addition, other predicted variables (e.g., belowground respiration) differed from observations in both magnitude and direction, indicating that CLM4.5 has inadequate underlying mechanisms for representing high-latitude ecosystems. On the basis of observational synthesis, we attribute the model-observation differences to missing representations of microbial dynamics, aboveground and belowground coupling, and nutrient cycling, and we use the observational meta-analysis to discuss potential approaches to improving the current models. However, we also urge caution concerning the selection of data sets and experiments for meta-analysis. For example, the concentrations of nitrogen applied in the synthesized field experiments (average = 72 kg ha-1 yr-1) are many times higher than projected soil nitrogen concentrations (from nitrogen deposition and release during mineralization), which precludes a rigorous evaluation of the model responses to likely nitrogen perturbations. Overall, we demonstrate that elucidating ecological mechanisms via meta-analysis can identify deficiencies in ecosystem models and empirical experiments.

Mean wind patterns and snow depths in an alpine-subalpine ecosystem as measured by damage to coniferous trees

Treesearch

G. L. Wooldridge; R. C. Musselman; R. A. Sommerfeld; D. G. Fox; B. H. Connell

1996-01-01

1. Deformations of Engelmann spruce and subalpine fir trees were surveyed for the purpose of determining climatic wind speeds and directions and snow depths in the Glacier Lakes Ecosystem Experiments Site (GLEES) in the Snowy Range of southeastern Wyoming, USA. Tree deformations were recorded at 50- and 100-m grid intervals over areas of c. 30 ha and 300 ha,...

Mineral soil and solution responses to experimental N and S enrichment at the Bear Brook Watershed in Maine (BBWM)

Treesearch

I. Fernandez; L. Rustad; M. David; K. Nadelhoffer; M. Mitchell

1999-01-01

Buried mineral soil-bag,, and natural solutions were studied as indicators of forest ecosystem response to elevated N and S inputs at the Bear Brook Watershed in Maine (BBWM). The BBWM is the site of a paired watershed manipulation experiment in a northern New England forested ecosystem. The study includes two small (~10 ha each) catchments dominated by northern...

Leveraging 35 years of Pinus taeda research in the southeastern US to constrain forest carbon cycle predictions: regional data assimilation using ecosystem experiments

Treesearch

R. Quinn Thomas; Evan B. Brooks; Annika L. Jersild; Eric J. Ward; Randolph H. Wynne; Timothy J. Albaugh; Heather Dinon-Aldridge; Harold E. Burkhart; Jean-Christophe Domec; Timothy R. Fox; Carlos A. Gonzalez-Benecke; Timothy A. Martin; Asko Noormets; David A. Sampson; Robert O. Teskey

2017-01-01

Predicting how forest carbon cycling will change in response to climate change and management depends on the collective knowledge from measurements across environmental gradients, ecosystem manipulations of global change factors, and mathematical models. Formally integrating these sources of knowledge through data assimilation, or model–data fusion, allows the use of...

Simulated response of conterminous United States ecosystems to climate change at different levels of fire suppression, CO2 emission rate, and growth response to CO2

Treesearch

James M. Lenihan; Dominique Bachelet; Ronald P. Neilson; Raymond Drapek

2008-01-01

A modeling experiment was designed to investigate the impact of fire management, CO2 emission rate, and the growth response to CO2 on the response of ecosystems in the conterminous United States to climate scenarios produced by three different general circulation models (GCMs) as simulated by the MCl Dynamic General...

Changes to dryland rainfall result in rapid moss mortality and altered soil fertility

USGS Publications Warehouse

Reed, Sasha C.; Coe, Kirsten K.; Sparks, Jed P.; Housman, David C.; Zelikova, Tamara J.; Belnap, Jayne

2012-01-01

Arid and semi-arid ecosystems cover ~40% of Earth’s terrestrial surface, but we know little about how climate change will affect these widespread landscapes. Like many drylands, the Colorado Plateau in southwestern United States is predicted to experience elevated temperatures and alterations to the timing and amount of annual precipitation. We used a factorial warming and supplemental rainfall experiment on the Colorado Plateau to show that altered precipitation resulted in pronounced mortality of the widespread moss Syntrichia caninervis. Increased frequency of 1.2 mm summer rainfall events reduced moss cover from ~25% of total surface cover to <2% after only one growing season, whereas increased temperature had no effect. Laboratory measurements identified a physiological mechanism behind the mortality: small precipitation events caused a negative moss carbon balance, whereas larger events maintained net carbon uptake. Multiple metrics of nitrogen cycling were notably different with moss mortality and had significant implications for soil fertility. Mosses are important members in many dryland ecosystems and the community changes observed here reveal how subtle modifications to climate can affect ecosystem structure and function on unexpectedly short timescales. Moreover, mortality resulted from increased precipitation through smaller, more frequent events, underscoring the importance of precipitation event size and timing, and highlighting our inadequate understanding of relationships between climate and ecosystem function in drylands.

Biological soil crusts (biocrusts) as a model system in community, landscape and ecosystem ecology

USGS Publications Warehouse

Bowker, Matthew A.; Maestre, Fernando T.; Eldridge, David; Belnap, Jayne; Castillo-Monroy, Andrea; Escolar, Cristina; Soliveres, Santiago

2014-01-01

Model systems have had a profound influence on the development of ecological theory and general principles. Compared to alternatives, the most effective models share some combination of the following characteristics: simpler, smaller, faster, general, idiosyncratic or manipulable. We argue that biological soil crusts (biocrusts) have unique combinations of these features that should be more widely exploited in community, landscape and ecosystem ecology. In community ecology, biocrusts are elucidating the importance of biodiversity and spatial pattern for maintaining ecosystem multifunctionality due to their manipulability in experiments. Due to idiosyncrasies in their modes of facilitation and competition, biocrusts have led to new models on the interplay between environmental stress and biotic interactions and on the maintenance of biodiversity by competitive processes. Biocrusts are perhaps one of the best examples of micro-landscapes—real landscapes that are small in size. Although they exhibit varying patch heterogeneity, aggregation, connectivity and fragmentation, like macro-landscapes, they are also compatible with well-replicated experiments (unlike macro-landscapes). In ecosystem ecology, a number of studies are imposing small-scale, low cost manipulations of global change or state factors in biocrust micro-landscapes. The versatility of biocrusts to inform such disparate lines of inquiry suggests that they are an especially useful model system that can enable researchers to see ecological principles more clearly and quickly.

2015 DOE Final UF Report. Effects of Warming the Deep Soil and Permafrost on Ecosystem Carbon Balance in Alaskan Tundra. A Coupled Measurement and Modeling Approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schuur, Edward

2015-06-11

The major research goal of this project was to understand and quantify the fate of carbon stored in permafrost ecosystems using a combination of field and laboratory experiments to measure isotope ratios and C fluxes in a tundra ecosystem exposed to experimental warming. Field measurements centered on the establishment of a two-factor experimental warming using a snow fence and open top chambers to increase winter and summer temperatures alone, and in combination, at a tundra field site at the Eight Mile Lake watershed near Healy, Alaska. The objective of this experimental warming was to significantly raise air and deep soilmore » temperatures and increase the depth of thaw beyond that of previous warming experiments. Detecting the loss and fate of the old permafrost C pool remains a major challenge. Because soil C has been accumulating in these ecosystems over the past 10,000 years, there is a strong difference between the radiocarbon isotopic composition of C deep in the soil profile and permafrost compared to that near the soil surface. This large range of isotopic variability is unique to radiocarbon and provides a valuable and sensitive fingerprint for detecting the loss of old soil C as permafrost thaws.« less

How Does Tree Density Affect Water Loss of Peatlands? A Mesocosm Experiment

PubMed Central

Limpens, Juul; Holmgren, Milena; Jacobs, Cor M. J.; Van der Zee, Sjoerd E. A. T. M.; Karofeld, Edgar; Berendse, Frank

2014-01-01

Raised bogs have accumulated more atmospheric carbon than any other terrestrial ecosystem on Earth. Climate-induced expansion of trees and shrubs may turn these ecosystems from net carbon sinks into sources when associated with reduced water tables. Increasing water loss through tree evapotranspiration could potentially deepen water tables, thus stimulating peat decomposition and carbon release. Bridging the gap between modelling and field studies, we conducted a three-year mesocosm experiment subjecting natural bog vegetation to three birch tree densities, and studied the changes in subsurface temperature, water balance components, leaf area index and vegetation composition. We found the deepest water table in mesocosms with low tree density. Mesocosms with high tree density remained wettest (i.e. highest water tables) whereas the control treatment without trees had intermediate water tables. These differences are attributed mostly to differences in evapotranspiration. Although our mesocosm results cannot be directly scaled up to ecosystem level, the systematic effect of tree density suggests that as bogs become colonized by trees, the effect of trees on ecosystem water loss changes with time, with tree transpiration effects of drying becoming increasingly offset by shading effects during the later phases of tree encroachment. These density-dependent effects of trees on water loss have important implications for the structure and functioning of peatbogs. PMID:24632565

Biodiversity promotes primary productivity and growing season lengthening at the landscape scale

PubMed Central

Niklaus, Pascal A.

2017-01-01

Experiments have shown positive biodiversity-ecosystem functioning (BEF) relationships in small plots with model communities established from species pools typically comprising few dozen species. Whether patterns found can be extrapolated to complex, nonexperimental, real-world landscapes that provide ecosystem services to humans remains unclear. Here, we combine species inventories from a large-scale network of 447 1-km2 plots with remotely sensed indices of primary productivity (years 2000–2015). We show that landscape-scale productivity and its temporal stability increase with the diversity of plants and other taxa. Effects of biodiversity indicators on productivity were comparable in size to effects of other important drivers related to climate, topography, and land cover. These effects occurred in plots that integrated different ecosystem types (i.e., metaecosystems) and were consistent over vast environmental and altitudinal gradients. The BEF relations we report are as strong or even exceed the ones found in small-scale experiments, despite different community assembly processes and a species pool comprising nearly 2,000 vascular plant species. Growing season length increased progressively over the observation period, and this shift was accelerated in more diverse plots, suggesting that a large species pool is important for adaption to climate change. Our study further implies that abiotic global-change drivers may mediate ecosystem functioning through biodiversity changes. PMID:28874547

An experimental analysis of granivory in a desert ecosystem: Progress report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brown, J.H.

1987-03-01

Controlled, replicated experiments are revealing the network of interactions that determine structure, dynamics, and energy transfer in a desert community that is functionally interconnected by the consumption of seeds (granivory). This community includes seed-eating rodents, ants, and birds, seed-producing annual and perennial plants, and other kinds of organisms that interact with these. The experiments entail removal of important species or functional groups of granivores or plants and supplementation of seed resources. The results demonstrate a large number of direct and indirect interactions that have important effects on the abundance of species and functional groups, the structure of the community, andmore » the dynamics of energy flow. The results suggest that networks of interaction are structured with sufficient overlap in resource requirements and interconnections through indirect pathways that community- and ecosystem-level processes, such as energy flow, are relatively insensitive to major perturbations in the abundance of particular species or functional groups. This preliminary finding has important implications for understanding the response of ecosystems to natural and human-caused perturbations, for the management of agricultural and other human-modified ecosystems, and for the design of perturbation-resistant networks for acquisition and distribution of human resources such energy and information. 44 refs.« less

Changing Arctic ecosystems--the role of ecosystem changes across the Boreal-Arctic transition zone on the distribution and abundance of wildlife populations

USGS Publications Warehouse

McNew, Lance; Handel, Colleen M.; Pearce, John; DeGange, Anthony R.; Holland-Bartels, Leslie; Whalen, Mary

2013-01-01

Arctic and boreal ecosystems provide important breeding habitat for more than half of North America’s migratory birds as well as many resident species. Northern landscapes are projected to experience more pronounced climate-related changes in habitat than most other regions. These changes include increases in shrub growth, conversion of tundra to forest, alteration of wetlands, shifts in species’ composition, and changes in the frequency and scale of fires and insect outbreaks. Changing habitat conditions, in turn, may have significant effects on the distribution and abundance of wildlife in these critical northern ecosystems. The U.S. Geological Survey (USGS) is conducting studies in the Boreal–Arctic transition zone of Alaska, an environment of accelerated change in this sensitive margin between Arctic tundra and boreal forest.

Diversity Promotes Temporal Stability across Levels of Ecosystem Organization in Experimental Grasslands

PubMed Central

Proulx, Raphaël; Wirth, Christian; Voigt, Winfried; Weigelt, Alexandra; Roscher, Christiane; Attinger, Sabine; Baade, Jussi; Barnard, Romain L.; Buchmann, Nina; Buscot, François; Eisenhauer, Nico; Fischer, Markus; Gleixner, Gerd; Halle, Stefan; Hildebrandt, Anke; Kowalski, Esther; Kuu, Annely; Lange, Markus; Milcu, Alex; Niklaus, Pascal A.; Oelmann, Yvonne; Rosenkranz, Stephan; Sabais, Alexander; Scherber, Christoph; Scherer-Lorenzen, Michael; Scheu, Stefan; Schulze, Ernst-Detlef; Schumacher, Jens; Schwichtenberg, Guido; Soussana, Jean-François; Temperton, Vicky M.; Weisser, Wolfgang W.; Wilcke, Wolfgang; Schmid, Bernhard

2010-01-01

The diversity–stability hypothesis states that current losses of biodiversity can impair the ability of an ecosystem to dampen the effect of environmental perturbations on its functioning. Using data from a long-term and comprehensive biodiversity experiment, we quantified the temporal stability of 42 variables characterizing twelve ecological functions in managed grassland plots varying in plant species richness. We demonstrate that diversity increases stability i) across trophic levels (producer, consumer), ii) at both the system (community, ecosystem) and the component levels (population, functional group, phylogenetic clade), and iii) primarily for aboveground rather than belowground processes. Temporal synchronization across studied variables was mostly unaffected with increasing species richness. This study provides the strongest empirical support so far that diversity promotes stability across different ecological functions and levels of ecosystem organization in grasslands. PMID:20967213

Using ground- and satellite-based measurements and models to quantify response to multiple disturbances and climate change in South African semi-arid ecosystems

NASA Astrophysics Data System (ADS)

Falge, Eva; Brümmer, Christian; Schmullius, Christiane; Scholes, Robert; Twine, Wayne; Mudau, Azwitamisi; Midgley, Guy; Hickler, Thomas; Bradshaw, Karen; Lück, Wolfgang; Thiel-Clemen, Thomas; du Toit, Justin; Sankaran, Vaith; Kutsch, Werner

2016-04-01

Sub-Saharan Africa currently experiences significant changes in shrubland, savanna and mixed woodland ecosystems driving degradation, affecting fire frequency and water availability, and eventually fueling climate change. The project 'Adaptive Resilience of Southern African Ecosystems' (ARS AfricaE) conducts research and develops scenarios of ecosystem development under climate change, for management support in conservation or for planning rural area development. For a network of research clusters along an aridity gradient in South Africa, we measure greenhouse gas exchange, ecosystem structure and eco-physiological properties as affected by land use change at paired sites with natural and altered vegetation. We set up dynamic vegetation models and individual-based models to predict ecosystem dynamics under (post) disturbance managements. We monitor vegetation amount and heterogeneity using remotely sensed images and aerial photography over several decades to examine time series of land cover change. Finally, we investigate livelihood strategies with focus on carbon balance components to develop sustainable management strategies for disturbed ecosystems and land use change. Emphasis is given on validation of estimates obtained from eddy covariance, model approaches and satellite derivations. We envision our methodological approach on a network of research clusters a valuable means to investigate potential linkages to concepts of adaptive resilience.

Multiple resource use efficiency (mRUE): A new concept for ecosystem production

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, Juanjuan; Chen, Jiquan; Miao, Yuan

The resource-driven concept, which is an important school for investigating ecosystem production, has been applied for decades. However, the regulatory mechanisms of production by multiple resources remain unclear. We formulated a new algorithm model that integrates multiple resource uses to study ecosystem production and tested its applications on a water-availability gradient in semi-arid grassland. The result of our experiment showed that changes in water availability significantly affected the resources of light and nitrogen, and altered the relationships among multiple resource absorption rate (ε), multiple resource use efficiency (mRUE), and available resource (R avail). The increased water availability suppressed ecosystem mRUEmore » (i.e., “declining marginal returns”); The changes in mRUE had a negative effect on ε (i.e., “inverse feedback”). These two processes jointly regulated that the stimulated single resource availability would promote ecosystem production rather than suppress it, even when mRUE was reduced. This study illustrated the use of the mRUE model in exploring the coherent relationships among the key parameters on regulating the ecosystem production for future modeling, and evaluated the sensitivity of this conceptual model under different dataset properties. Furthermore, this model needs extensive validation by the ecological community before it can extrapolate this method to other ecosystems in the future.« less

A coordinated set of ecosystem research platforms open to international research in ecotoxicology, AnaEE-France.

PubMed

Mougin, Christian; Azam, Didier; Caquet, Thierry; Cheviron, Nathalie; Dequiedt, Samuel; Le Galliard, Jean-François; Guillaume, Olivier; Houot, Sabine; Lacroix, Gérard; Lafolie, François; Maron, Pierre-Alain; Michniewicz, Radika; Pichot, Christian; Ranjard, Lionel; Roy, Jacques; Zeller, Bernd; Clobert, Jean; Chanzy, André

2015-10-01

The infrastructure for Analysis and Experimentation on Ecosystems (AnaEE-France) is an integrated network of the major French experimental, analytical, and modeling platforms dedicated to the biological study of continental ecosystems (aquatic and terrestrial). This infrastructure aims at understanding and predicting ecosystem dynamics under global change. AnaEE-France comprises complementary nodes offering access to the best experimental facilities and associated biological resources and data: Ecotrons, seminatural experimental platforms to manipulate terrestrial and aquatic ecosystems, in natura sites equipped for large-scale and long-term experiments. AnaEE-France also provides shared instruments and analytical platforms dedicated to environmental (micro) biology. Finally, AnaEE-France provides users with data bases and modeling tools designed to represent ecosystem dynamics and to go further in coupling ecological, agronomical, and evolutionary approaches. In particular, AnaEE-France offers adequate services to tackle the new challenges of research in ecotoxicology, positioning its various types of platforms in an ecologically advanced ecotoxicology approach. AnaEE-France is a leading international infrastructure, and it is pioneering the construction of AnaEE (Europe) infrastructure in the field of ecosystem research. AnaEE-France infrastructure is already open to the international community of scientists in the field of continental ecotoxicology.

Multiple resource use efficiency (mRUE): A new concept for ecosystem production

DOE PAGES

Han, Juanjuan; Chen, Jiquan; Miao, Yuan; ...

2016-11-21

The resource-driven concept, which is an important school for investigating ecosystem production, has been applied for decades. However, the regulatory mechanisms of production by multiple resources remain unclear. We formulated a new algorithm model that integrates multiple resource uses to study ecosystem production and tested its applications on a water-availability gradient in semi-arid grassland. The result of our experiment showed that changes in water availability significantly affected the resources of light and nitrogen, and altered the relationships among multiple resource absorption rate (ε), multiple resource use efficiency (mRUE), and available resource (R avail). The increased water availability suppressed ecosystem mRUEmore » (i.e., “declining marginal returns”); The changes in mRUE had a negative effect on ε (i.e., “inverse feedback”). These two processes jointly regulated that the stimulated single resource availability would promote ecosystem production rather than suppress it, even when mRUE was reduced. This study illustrated the use of the mRUE model in exploring the coherent relationships among the key parameters on regulating the ecosystem production for future modeling, and evaluated the sensitivity of this conceptual model under different dataset properties. Furthermore, this model needs extensive validation by the ecological community before it can extrapolate this method to other ecosystems in the future.« less

Multiple Resource Use Efficiency (mRUE): A New Concept for Ecosystem Production.

PubMed

Han, Juanjuan; Chen, Jiquan; Miao, Yuan; Wan, Shiqiang

2016-11-21

The resource-driven concept, which is an important school for investigating ecosystem production, has been applied for decades. However, the regulatory mechanisms of production by multiple resources remain unclear. We formulated a new algorithm model that integrates multiple resource uses to study ecosystem production and tested its applications on a water-availability gradient in semi-arid grassland. The result of our experiment showed that changes in water availability significantly affected the resources of light and nitrogen, and altered the relationships among multiple resource absorption rate (ε), multiple resource use efficiency (mRUE), and available resource (R avail ). The increased water availability suppressed ecosystem mRUE (i.e., "declining marginal returns"); The changes in mRUE had a negative effect on ε (i.e., "inverse feedback"). These two processes jointly regulated that the stimulated single resource availability would promote ecosystem production rather than suppress it, even when mRUE was reduced. This study illustrated the use of the mRUE model in exploring the coherent relationships among the key parameters on regulating the ecosystem production for future modeling, and evaluated the sensitivity of this conceptual model under different dataset properties. However, this model needs extensive validation by the ecological community before it can extrapolate this method to other ecosystems in the future.

Trophic Tangles through Time? Opposing Direct and Indirect Effects of an Invasive Omnivore on Stream Ecosystem Processes

PubMed Central

Moore, Jonathan W.; Carlson, Stephanie M.; Twardochleb, Laura A.; Hwan, Jason L.; Fox, Justin M.; Hayes, Sean A.

2012-01-01

Omnivores can impact ecosystems via opposing direct or indirect effects. For example, omnivores that feed on herbivores and plants could either increase plant biomass due to the removal of herbivores or decrease plant biomass due to direct consumption. Thus, empirical quantification of the relative importance of direct and indirect impacts of omnivores is needed, especially the impacts of invasive omnivores. Here we investigated how an invasive omnivore (signal crayfish, Pacifastacus leniusculus) impacts stream ecosystems. First, we performed a large-scale experiment to examine the short-term (three month) direct and indirect impacts of crayfish on a stream food web. Second, we performed a comparative study of un-invaded areas and areas invaded 90 years ago to examine whether patterns from the experiment scaled up to longer time frames. In the experiment, crayfish increased leaf litter breakdown rate, decreased the abundance and biomass of other benthic invertebrates, and increased algal production. Thus, crayfish controlled detritus via direct consumption and likely drove a trophic cascade through predation on grazers. Consistent with the experiment, the comparative study also found that benthic invertebrate biomass decreased with crayfish. However, contrary to the experiment, crayfish presence was not significantly associated with higher leaf litter breakdown in the comparative study. We posit that during invasion, generalist crayfish replace the more specialized native detritivores (caddisflies), thereby leading to little long-term change in net detrital breakdown. A feeding experiment revealed that these native detritivores and the crayfish were both effective consumers of detritus. Thus, the impacts of omnivores represent a temporally-shifting interplay between direct and indirect effects that can control basal resources. PMID:23209810

Oyster Reef Communities in the Chesapeake Bay: A Brief Primer. VORTEX: Virginia's Oyster Reef Teaching EXperience.

ERIC Educational Resources Information Center

Harding, Juliana M.; Mann, Roger; Clark, Vicki P.

This document introduces Virginia's Oyster Reef Teaching EXperience (VORTEX), which is an interdisciplinary program focusing on the importance of oyster reef communities in the Chesapeake Bay ecosystem. The VORTEX program uses field and laboratory experience supported by multimedia instruction. This document presents an overview on the biology of…

Three years exclusion of large herbivores in a high arctic mire in NE Greenland resulted in changed vegetation density and greenhouse gas emission and uptake

NASA Astrophysics Data System (ADS)

Falk, Julie M.; Schmidt, Niels Martin; Christensen, Torben R.; Forchhammer, Mads C.; Jackowicz-Korczynski, Marcin; Ström, Lena

2014-05-01

Herbivory is an important part of many ecosystems and their presence effects the ecosystems carbon balance with both direct and indirect effects. Little is known about what will happen to an arctic ecosystem that is influenced by herbivory, if the animals disappear. We hypothesized that trampling and grazing by large herbivores influence the vegetation density and composition and hereby the carbon balance. Method: In 2010 an in-situ field experiment in Zackenberg, NE Greenland, were initiated to study the effects of herbivory on the vegetation and carbon balance. Exclosures were established to exclude the muskoxen (Ovibos moschatus), which are a natural part of these ecosystems. The experiment consists of five block replicates with three treatments within each block, i.e., control, exclosure and a snow fence (the treatment area is 10x10 m and the fences are 1 m high). During the growing season we have since 2011 performed weekly measurements of CO2 and CH4fluxes, the concentration of labile substrate for CH4 formation (organic acid concentration) in pore-water and additional ecosystem properties, i.e., water table depth, active layer depth and soil temperature. In 2013 a detailed analysis of the vascular plant species composition and density within each measurement plot were performed. Furthermore biomass (including mosses) samples 20x20 cm were harvested within all treatments. Results: The third year after the initiation of the experiment we observed a clear effect of excluding muskoxen grazing from the ecosystem. The exclosures had lower uptake of CO2 and lower CH4 emission. The vegetation analysis inside the plots showed a decrease in total number of vascular tillers and of Eriophorum scheuchzeri (ES) tillers. Correspondingly, the biomass samples from the exclosures had lower number of total plant tillers, ES tillers, total green leaves and green ES leaves and the height of all vascular plants and of ES plants were higher. Finally, the dry weight of the biomass showed that there were more mosses and old biomass inside exclosures. Conclusions: Removing muskoxen grazing and physical presence has dramatic effects on the ecosystem. As there is no trampling inside the exclosures the mosses become more dominating and starts to grow upwards, due to less compaction. As there is no consumption of the vascular plants, all the old biomass remains on the ground surface, most likely leading to light limitation of the vascular plants and they therefore decrease in number of tillers and in green leaves. The thicker moss layer forces the vascular plants to grow taller, as seen inside the exclosures. The decrease of CO2 uptake can partly by explained by the lower number of vascular plants, while the decrease in CH4 emission most likely is connected to lower CO2 uptake, less vascular plants and lower overall carbon allocation below ground and hereby less root exudation. The future of the muskoxen in a changing arctic environment are uncertain, this experiment is pointing towards the potentially large effect that herbivory has on the carbon balance of natural ecosystems in the Arctic.

IMPACTS OF INTERACTING ELEVATED ATMOSPHERIC CO2 AND O3 ON THE STRUCTURE AND FUNCTIONING OF A NORTHERN FOREST ECOSYSTEM: OPERATING AND DECOMMISSIONING THE ASPEN FACE PROJECT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burton, Andrew J.; Zak, Donald R.; Kubiske, Mark E.

Two of the most important and pervasive greenhouse gases driving global change and impacting forests in the U.S. and around the world are atmospheric CO2 and tropospheric O3. As the only free air, large-scale manipulative experiment studying the interaction of elevated CO2 and O3 on forests, the Aspen FACE experiment was uniquely designed to address the long-term ecosystem level impacts of these two greenhouse gases on aspen-birch-maple forests, which dominate the richly forested Lake States region. The project was established in 1997 to address the overarching scientific question: “What are the effects of elevated [CO2] and [O3], alone and inmore » combination, on the structure and functioning of northern hardwood forest ecosystems?” From 1998 through the middle of the 2009 growing season, we examined the interacting effects of elevated CO2 and O3 on ecosystem processes in an aggrading northern forest ecosystem to compare the responses of early-successional, rapid-growing shade intolerant trembling aspen and paper birch to those of a late successional, slower growing shade tolerant sugar maple. Fumigations with elevated CO2 (560 ppm during daylight hours) and O3 (approximately 1.5 x ambient) were conducted during the growing season from 1998 to 2008, and in 2009 through harvest date. Response variables quantified during the experiment included growth, competitive interactions and stand dynamics, physiological processes, plant nutrient status and uptake, tissue biochemistry, litter quality and decomposition rates, hydrology, soil respiration, microbial community composition and respiration, VOC production, treatment-pest interactions, and treatment-phenology interactions. In 2009, we conducted a detailed harvest of the site. The harvest included detailed sampling of a subset of trees by component (leaves and buds, fine branches, coarse branches and stem, coarse roots, fine roots) and excavation of soil to a depth of 1 m. Throughout the experiment, aspen and birch photosynthesis increased with elevated CO2 and tended to decrease with elevated O3, compared to the control. In contrast to aspen and birch, maple photosynthesis was not enhanced by elevated CO2. Elevated O3 did not cause significant reductions in maximum photosynthesis in birch or maple. In addition, photosynthesis in ozone sensitive clones was affected to a much greater degree than that in ozone tolerant aspen clones. Treatment effects on photosynthesis contributed to CO2 stimulation of aboveground and belowground growth that was species and genotype dependent, with birch and aspen being most responsive and maple being least responsive. The positive effects of elevated CO2 on net primary productivity NPP were sustained through the end of the experiment, but negative effects of elevated O3 on NPP had dissipated during the final three years of treatments. The declining response to O3 over time resulted from the compensatory growth of O3-tolerant genotypes and species as the growth of O3-sensitive individuals declined over time. Cumulative NPP over the entire experiment was 39% greater under elevated CO2 and 10% lower under elevated O3. Enhanced NPP under elevated CO2 was sustained by greater root exploration of soil for growth-limiting N, as well as more rapid rates of litter decomposition and microbial N release during decay. Results from Aspen FACE clearly indicate that plants growing under elevated carbon dioxide, regardless of community type or ozone level, obtained significantly greater amounts of soil N. These results indicate that greater plant growth under elevated carbon dioxide has not led to “progressive N limitation”. If similar forests growing throughout northeastern North America respond in the same manner, then enhanced forest NPP under elevated CO2 may be sustained for a longer duration than previously thought, and the negative effect of elevated O3 may be diminished by compensatory growth of O3-tolerant plants as they begin to dominate forest communities. By the end of the experiment, elevated CO2 increased ecosystem C content by 11%, whereas elevated O3 decreased ecosystem C content by 9%. Total ecosystem C content in the interaction treatment (elevated CO2 and O3) did not significantly differ from that of the control. Total ecosystem C content responded similarly to the treatments across the three forest communities. The treatment effects on ecosystem C content resulted from differences in tree biomass, particularly woody tissues (branches, stem, and coarse roots), and lower C content in the near-surface mineral soil. During its duration, the Aspen FACE project involved collaboration between scientists from 9 countries, and over the course of the experiment there were over 120 Aspen FACE scientific users. These scientists helped produce 75 publications during the most recent funding period (2008-2014) and 207 peer-reviewed publications (169 in refereed journals) since the beginning of the project.« less

Sensitivity of productivity and respiration to water availability determines the net ecosystem exchange of carbon terrestrial ecosystems of the United States

NASA Astrophysics Data System (ADS)

Liu, Z.; Ballantyne, A.; Poulter, B.; Anderegg, W.; Jacobson, A. R.; Miller, J. B.

2017-12-01

Interannual variability (IAV) of atmospheric CO2 is primarily driven by fluctuations in net carbon exchange (NEE) by terrestrial ecosystems. Recent analyses suggested that global terrestrial carbon uptake is dominated by the sensitivity of productivity to precipitation in semi-arid ecosystems, or sensitivity of respiration to temperature in tropical ecosystems. There is a need to better understand factors that control the carbon balance of land ecosystems across spatial and temporal scales. Here we used multiple observational dataset to assess: (1) What are the dominant processes controlling the IAV of NEE in terrestrial ecosystem? What are the climatic controls on the variability gross primary productivity (GPP) and total ecosystem respiration (TER) in the contiguous United States (CONUS). Our analysis revealed that there is a strong positive correlation between IAV of GPP and IAV of NEE in drier (mean annual precipitation: MAP < 750mm) western ecosystem, while there is no correlation between IAV of GPP and IAV of NEE in moist (MAP > 750mm) eastern ecosystem using observational dataset. Both βspatial and βtemporal of GPP and TER to precipitation exhibit an emergent threshold where GPP is more sensitive than TER to precipitation in semi-arid western ecosystems and TER is more sensitive than GPP to precipitation in more humid eastern ecosystems. This emergent ecosystem threshold was evident in several independent observations. However, analyses from 10 TRENDY models indicate current Dynamic Global Vegetation Models (DGVMs) tend to overestimate the sensitivity of NEE to GPP and underestimate the sensitivity of NEE to TER to precipitation across CONUS ecosystems. TER experiments showed that commonly used TER models failed to capture the IAV of TER in the moist region in CONUS. This is because heterotrophic respiration (Rh) was relatively independent of GPP in moist regions of CONUS, but was too tightly coupled to GPP in the DGVMs. The emergent thresholds at the ecosystem and continental scale may help reconcile model simulations and observations of terrestrial carbon processes.

Biodiversity mediates top-down control in eelgrass ecosystems: a global comparative-experimental approach.

PubMed

Duffy, J Emmett; Reynolds, Pamela L; Boström, Christoffer; Coyer, James A; Cusson, Mathieu; Donadi, Serena; Douglass, James G; Eklöf, Johan S; Engelen, Aschwin H; Eriksson, Britas Klemens; Fredriksen, Stein; Gamfeldt, Lars; Gustafsson, Camilla; Hoarau, Galice; Hori, Masakazu; Hovel, Kevin; Iken, Katrin; Lefcheck, Jonathan S; Moksnes, Per-Olav; Nakaoka, Masahiro; O'Connor, Mary I; Olsen, Jeanine L; Richardson, J Paul; Ruesink, Jennifer L; Sotka, Erik E; Thormar, Jonas; Whalen, Matthew A; Stachowicz, John J

2015-07-01

Nutrient pollution and reduced grazing each can stimulate algal blooms as shown by numerous experiments. But because experiments rarely incorporate natural variation in environmental factors and biodiversity, conditions determining the relative strength of bottom-up and top-down forcing remain unresolved. We factorially added nutrients and reduced grazing at 15 sites across the range of the marine foundation species eelgrass (Zostera marina) to quantify how top-down and bottom-up control interact with natural gradients in biodiversity and environmental forcing. Experiments confirmed modest top-down control of algae, whereas fertilisation had no general effect. Unexpectedly, grazer and algal biomass were better predicted by cross-site variation in grazer and eelgrass diversity than by global environmental gradients. Moreover, these large-scale patterns corresponded strikingly with prior small-scale experiments. Our results link global and local evidence that biodiversity and top-down control strongly influence functioning of threatened seagrass ecosystems, and suggest that biodiversity is comparably important to global change stressors. © 2015 John Wiley & Sons Ltd/CNRS.

Can short-term and small-scale experiments reflect nutrient limitation on phytoplankton in natural lakes?

NASA Astrophysics Data System (ADS)

Wang, Haijun; Li, Yan; Feng, Weisong; Yu, Qing; Xiao, Xucheng; Liang, Xiaomin; Shao, Jianchun; Ma, Shuonan; Wang, Hongzhu

2017-05-01

Whether it is necessary to reduce nitrogen (N) and/or phosphorus (P) input to mitigate lake eutrophication is controversial. The controversy stems mainly from differences in time and space in previous studies that support the contrasting ideas. To test the response of phytoplankton to various combinations of nutrient control strategies in mesocosms and the possibility of reflecting the conditions in natural ecosystems with short-term experiments, a 9-month experiment was carried out in eight 800-L tanks with four nutrient level combinations (+N+P, -N+P, +N-P, and -N-P), with an 18-month whole-ecosystem experiment in eight 800-m 2 ponds as the reference. Phytoplankton abundance was determined by P not N, regardless of the initial TN/TP level, which was in contrast to the nutrient limitation predicted by the N/P theory. Net natural N inputs were calculated to be 4.9, 6.8, 1.5, and 3.0 g in treatments +N+P, -N+P, +N-P, and -N-P, respectively, suggesting that N deficiency and P addition may promote natural N inputs to support phytoplankton development. However, the compensation process was slow, as suggested by an observed increase in TN after 3 weeks in -N+P and 2 months in -N-P in the tank experiment, and after 3 months in -N +P and 3 months in -N-P in our pond experiment. Obviously, such a slow process cannot be simulated in short-term experiments. The natural N inputs cannot be explained by planktonic N-fixation because N-fixing cyanobacteria were scarce, which was probably because there was a limited pool of species in the tanks. Therefore, based on our results we argue that extrapolating short-term, small-scale experiments to large natural ecosystems does not give reliable, accurate results.

Warming alters the energetic structure and function but not resilience of soil food webs

PubMed Central

Schwarz, Benjamin; Barnes, Andrew D.; Thakur, Madhav P.; Brose, Ulrich; Ciobanu, Marcel; Reich, Peter B.; Rich, Roy L.; Rosenbaum, Benjamin; Stefanski, Artur; Eisenhauer, Nico

2017-01-01

Climate warming is predicted to alter the structure, stability, and functioning of food webs1–5. Yet, despite the importance of soil food webs for energy and nutrient turnover in terrestrial ecosystems, warming effects on these food webs—particularly in combination with other global change drivers—are largely unknown. Here, we present results from two complementary field experiments testing the interactive effects of warming with forest canopy disturbance and drought on energy fluxes in boreal-temperate ecotonal forest soil food webs. The first experiment applied a simultaneous above- and belowground warming treatment (ambient, +1.7°C, +3.4°C) to closed canopy and recently clear-cut forest, simulating common forest disturbance6. The second experiment crossed warming with a summer drought treatment (-40% rainfall) in the clear-cut habitats. We show that warming reduces energy fluxes to microbes, while forest canopy disturbance and drought facilitates warming-induced increases in energy flux to higher trophic levels and exacerbates reductions in energy flux to microbes, respectively. Contrary to expectations, we find no change in whole-network resilience to perturbations, but significant losses of ecosystem functioning. Warming thus interacts with forest disturbance and drought, shaping the energetic structure of soil food webs and threatening the provisioning of multiple ecosystem functions in boreal-temperate ecotonal forests. PMID:29218059

Warming alters energetic structure and function but not resilience of soil food webs

NASA Astrophysics Data System (ADS)

Schwarz, Benjamin; Barnes, Andrew D.; Thakur, Madhav P.; Brose, Ulrich; Ciobanu, Marcel; Reich, Peter B.; Rich, Roy L.; Rosenbaum, Benjamin; Stefanski, Artur; Eisenhauer, Nico

2017-12-01

Climate warming is predicted to alter the structure, stability, and functioning of food webs1-5. Yet, despite the importance of soil food webs for energy and nutrient turnover in terrestrial ecosystems, the effects of warming on these food webs—particularly in combination with other global change drivers—are largely unknown. Here, we present results from two complementary field experiments that test the interactive effects of warming with forest canopy disturbance and drought on energy flux in boreal-temperate ecotonal forest soil food webs. The first experiment applied a simultaneous above- and belowground warming treatment (ambient, +1.7 °C, +3.4 °C) to closed-canopy and recently clear-cut forest, simulating common forest disturbance6. The second experiment crossed warming with a summer drought treatment (-40% rainfall) in the clear-cut habitats. We show that warming reduces energy flux to microbes, while forest canopy disturbance and drought facilitates warming-induced increases in energy flux to higher trophic levels and exacerbates the reduction in energy flux to microbes, respectively. Contrary to expectations, we find no change in whole-network resilience to perturbations, but significant losses in ecosystem functioning. Warming thus interacts with forest disturbance and drought, shaping the energetic structure of soil food webs and threatening the provisioning of multiple ecosystem functions in boreal-temperate ecotonal forests.

Context-dependent consumer control in New England tidal wetlands.

PubMed

Moore, Alexandria

2018-01-01

Recent studies in coastal wetlands have indicated that consumers may play an important role in regulating large-scale ecosystem processes. Predator removal experiments have shown significant differences in above-ground biomass production in the presence of higher level consumers, or predators. These results indicate that predators play an important role in regulating biomass production, but the extent to which this regulation impacts additional ecosystem functions, such as nutrient cycling and organic matter accumulation, is unclear. This study evaluated the impact that consumers have on large-scale ecosystem processes within southern New England tidal wetlands and contributes to the general understanding of trophic control in these systems. I established enclosure cages within three coastal wetlands and manipulated the presence of green crab predators to assess how trophic interactions affect ecosystem functions. Findings suggest that although these consumers may exert some top-down effects, other environmental factors, such as other consumers not studied here or bottom-up interactions, may variably play a larger role in the maintenance of ecosystem processes within the region. These results indicate that the loss of top-down control as an important mechanism influencing ecosystem functions may not hold for all wetlands along the full extent of the New England coastline.

Habitat structure mediates biodiversity effects on ecosystem properties

PubMed Central

Godbold, J. A.; Bulling, M. T.; Solan, M.

2011-01-01

Much of what we know about the role of biodiversity in mediating ecosystem processes and function stems from manipulative experiments, which have largely been performed in isolated, homogeneous environments that do not incorporate habitat structure or allow natural community dynamics to develop. Here, we use a range of habitat configurations in a model marine benthic system to investigate the effects of species composition, resource heterogeneity and patch connectivity on ecosystem properties at both the patch (bioturbation intensity) and multi-patch (nutrient concentration) scale. We show that allowing fauna to move and preferentially select patches alters local species composition and density distributions, which has negative effects on ecosystem processes (bioturbation intensity) at the patch scale, but overall positive effects on ecosystem functioning (nutrient concentration) at the multi-patch scale. Our findings provide important evidence that community dynamics alter in response to localized resource heterogeneity and that these small-scale variations in habitat structure influence species contributions to ecosystem properties at larger scales. We conclude that habitat complexity forms an important buffer against disturbance and that contemporary estimates of the level of biodiversity required for maintaining future multi-functional systems may need to be revised. PMID:21227969

User fees across ecosystem boundaries: Are SCUBA divers willing to pay for terrestrial biodiversity conservation?

PubMed

Roberts, Michaela; Hanley, Nick; Cresswell, Will

2017-09-15

While ecological links between ecosystems have been long recognised, management rarely crosses ecosystem boundaries. Coral reefs are susceptible to damage through terrestrial run-off, and failing to account for this within management threatens reef protection. In order to quantify the extent to that coral reef users are willing to support management actions to improve ecosystem quality, we conducted a choice experiment with SCUBA divers on the island of Bonaire, Caribbean Netherlands. Specifically, we estimated their willingness to pay to reduce terrestrial overgrazing as a means to improve reef health. Willingness to pay was estimated using the multinomial, random parameter and latent class logit models. Willingness to pay for improvements to reef quality was positive for the majority of respondents. Estimates from the latent class model determined willingness to pay for reef improvements of between $31.17 - $413.18/year, dependent on class membership. This represents a significant source of funding for terrestrial conservation, and illustrates the potential for user fees to be applied across ecosystem boundaries. We argue that such across-ecosystem-boundary funding mechanisms are an important avenue for future investigation in many connected systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

Habitat structure mediates biodiversity effects on ecosystem properties.

PubMed

Godbold, J A; Bulling, M T; Solan, M

2011-08-22

Much of what we know about the role of biodiversity in mediating ecosystem processes and function stems from manipulative experiments, which have largely been performed in isolated, homogeneous environments that do not incorporate habitat structure or allow natural community dynamics to develop. Here, we use a range of habitat configurations in a model marine benthic system to investigate the effects of species composition, resource heterogeneity and patch connectivity on ecosystem properties at both the patch (bioturbation intensity) and multi-patch (nutrient concentration) scale. We show that allowing fauna to move and preferentially select patches alters local species composition and density distributions, which has negative effects on ecosystem processes (bioturbation intensity) at the patch scale, but overall positive effects on ecosystem functioning (nutrient concentration) at the multi-patch scale. Our findings provide important evidence that community dynamics alter in response to localized resource heterogeneity and that these small-scale variations in habitat structure influence species contributions to ecosystem properties at larger scales. We conclude that habitat complexity forms an important buffer against disturbance and that contemporary estimates of the level of biodiversity required for maintaining future multi-functional systems may need to be revised.

Context-dependent consumer control in New England tidal wetlands

PubMed Central

2018-01-01

Recent studies in coastal wetlands have indicated that consumers may play an important role in regulating large-scale ecosystem processes. Predator removal experiments have shown significant differences in above-ground biomass production in the presence of higher level consumers, or predators. These results indicate that predators play an important role in regulating biomass production, but the extent to which this regulation impacts additional ecosystem functions, such as nutrient cycling and organic matter accumulation, is unclear. This study evaluated the impact that consumers have on large-scale ecosystem processes within southern New England tidal wetlands and contributes to the general understanding of trophic control in these systems. I established enclosure cages within three coastal wetlands and manipulated the presence of green crab predators to assess how trophic interactions affect ecosystem functions. Findings suggest that although these consumers may exert some top-down effects, other environmental factors, such as other consumers not studied here or bottom-up interactions, may variably play a larger role in the maintenance of ecosystem processes within the region. These results indicate that the loss of top-down control as an important mechanism influencing ecosystem functions may not hold for all wetlands along the full extent of the New England coastline. PMID:29771961

Species richness accelerates marine ecosystem restoration in the Coral Triangle.

PubMed

Williams, Susan L; Ambo-Rappe, Rohani; Sur, Christine; Abbott, Jessica M; Limbong, Steven R

2017-11-07

Ecosystem restoration aims to restore biodiversity and valuable functions that have been degraded or lost. The Coral Triangle is a hotspot for marine biodiversity held in its coral reefs, seagrass meadows, and mangrove forests, all of which are in global decline. These coastal ecosystems support valuable fisheries and endangered species, protect shorelines, and are significant carbon stores, functions that have been degraded by coastal development, destructive fishing practices, and climate change. Ecosystem restoration is required to mitigate these damages and losses, but its practice is in its infancy in the region. Here we demonstrate that species diversity can set the trajectory of restoration. In a seagrass restoration experiment in the heart of the Coral Triangle (Sulawesi, Indonesia), plant survival and coverage increased with the number of species transplanted. Our results highlight the positive role biodiversity can play in ecosystem restoration and call for revision of the common restoration practice of establishing a single target species, particularly in regions having high biodiversity. Coastal ecosystems affect human well-being in many important ways, and restoration will become ever more important as conservation efforts cannot keep up with their loss. Published under the PNAS license.

Alien invasions in aquatic ecosystems: toward an understanding of brook trout invasions and potential impacts on inland cutthroat trout in western North America

Treesearch

Jason B. Dunham; Susan B. Adams; Robert E. Schroeter; Douglas C. Novinger

2002-01-01

Experience from case studies of biological invasions in aquatic ecosystems has motivated a set of proposed empirical “rules” for understanding patterns of invasion and impacts on native species. Further evidence is needed to better understand these patterns, and perhaps contribute to a useful predictive theory of invasions. We reviewed the case of brook trout (

Effect of simulated monsoon failure on the carbon balance of mountain forests, Bhutan, eastern Himalayas

NASA Astrophysics Data System (ADS)

Wangdi, Norbu; Ahmed, Iftekhar; Zangmo, Norbu; Gratzer, Georg; Jandl, Robert; Schindlbacher, Andreas

2017-04-01

Extreme climatic events leading to severe disturbances in ecosystems are expected to increase globally. Such events carry strong potentials for severe reductions or whole losses of ecosystem services. This is particularly true for the Himalayas: they are located in a region forming a tipping element in the Earth's climate system. At a millennial time scale, complete breakdowns of the summer monsoon circulation and a resulting failure of the Indian summer monsoon rains have occurred several times during the last 1000 years. Climate change potentially increases the frequency of such monsoon failures and related mega-droughts. Given the significance of the region, the knowledge on the effects of climate change on forest ecosystem C dynamics is strikingly limited. While the effects of droughts are studied experimentally in Europe and North America, no precipitation manipulation experiments have been carried out in the Himalayas yet. We make use of natural forests with coexisting conifer and broadleaf as well as deciduous and evergreen species at slopes of stark environmental gradients for conducting a replicated large-scale five year throughfall exclosure experiment. We study drought response at individual tree and ecosystem levels. We present the effects of the experimental drought on the ecosystem carbon balance, integrating above- and belowground pools and fluxes such as heterotrophic and autotrophic soil respiration, litter fall and root turnover as well as above- and belowground tree growth. A preliminary assessment indicates that soil microbes were primarily affected during the first three years of simulated drought, whereas trees altered allocation patterns but survived the experimental drought. A detailed analysis will be presented at the conference.

Relevance of risk predictions derived from a chronic species sensitivity distribution with cadmium to aquatic populations and ecosystems

USGS Publications Warehouse

Mebane, C.A.

2010-01-01

Criteria to protect aquatic life are intended to protect diverse ecosystems, but in practice are usually developed from compilations of single-species toxicity tests using standard test organisms that were tested in laboratory environments. Species sensitivity distributions (SSDs) developed from these compilations are extrapolated to set aquatic ecosystem criteria. The protectiveness of the approach was critically reviewed with a chronic SSD for cadmium comprising 27 species within 21 genera. Within the data set, one genus had lower cadmium effects concentrations than the SSD fifth percentile-based criterion, so in theory this genus, the amphipod Hyalella, could be lost or at least allowed some level of harm by this criteria approach. However, population matrix modeling projected only slightly increased extinction risks for a temperate Hyalella population under scenarios similar to the SSD fifth percentile criterion. The criterion value was further compared to cadmium effects concentrations in ecosystem experiments and field studies. Generally, few adverse effects were inferred from ecosystem experiments at concentrations less than the SSD fifth percentile criterion. Exceptions were behavioral impairments in simplified food web studies. No adverse effects were apparent in field studies under conditions that seldom exceeded the criterion. At concentrations greater than the SSD fifth percentile, the magnitudes of adverse effects in the field studies were roughly proportional to the laboratory-based fraction of species with adverse effects in the SSD. Overall, the modeling and field validation comparisons of the chronic criterion values generally supported the relevance and protectiveness of the SSD fifth percentile approach with cadmium. ?? 2009 Society for Risk Analysis.

Biodiversity impacts ecosystem productivity as much as resources, disturbance, or herbivory.

PubMed

Tilman, David; Reich, Peter B; Isbell, Forest

2012-06-26

Although the impacts of the loss of biodiversity on ecosystem functioning are well established, the importance of the loss of biodiversity relative to other human-caused drivers of environmental change remains uncertain. Results of 11 experiments show that ecologically relevant decreases in grassland plant diversity influenced productivity at least as much as ecologically relevant changes in nitrogen, water, CO(2), herbivores, drought, or fire. Moreover, biodiversity became an increasingly dominant driver of ecosystem productivity through time, whereas effects of other factors either declined (nitrogen addition) or remained unchanged (all others). In particular, a change in plant diversity from four to 16 species caused as large an increase in productivity as addition of 54 kg · ha(-1) · y(-1) of fertilizer N, and was as influential as removing a dominant herbivore, a major natural drought, water addition, and fire suppression. A change in diversity from one to 16 species caused a greater biomass increase than 95 kg · ha(-1) · y(-1) of N or any other treatment. Our conclusions are based on >7,000 productivity measurements from 11 long-term experiments (mean length, ~ 13 y) conducted at a single site with species from a single regional species pool, thus controlling for many potentially confounding factors. Our results suggest that the loss of biodiversity may have at least as great an impact on ecosystem functioning as other anthropogenic drivers of environmental change, and that use of diverse mixtures of species may be as effective in increasing productivity of some biomass crops as fertilization and may better provide ecosystem services.

Partitioning direct and indirect effects reveals the response of water-limited ecosystems to elevated CO2.

PubMed

Fatichi, Simone; Leuzinger, Sebastian; Paschalis, Athanasios; Langley, J Adam; Donnellan Barraclough, Alicia; Hovenden, Mark J

2016-10-24

Increasing concentrations of atmospheric carbon dioxide are expected to affect carbon assimilation and evapotranspiration (ET), ultimately driving changes in plant growth, hydrology, and the global carbon balance. Direct leaf biochemical effects have been widely investigated, whereas indirect effects, although documented, elude explicit quantification in experiments. Here, we used a mechanistic model to investigate the relative contributions of direct (through carbon assimilation) and indirect (via soil moisture savings due to stomatal closure, and changes in leaf area index) effects of elevated CO 2 across a variety of ecosystems. We specifically determined which ecosystems and climatic conditions maximize the indirect effects of elevated CO 2 The simulations suggest that the indirect effects of elevated CO 2 on net primary productivity are large and variable, ranging from less than 10% to more than 100% of the size of direct effects. For ET, indirect effects were, on average, 65% of the size of direct effects. Indirect effects tended to be considerably larger in water-limited ecosystems. As a consequence, the total CO 2 effect had a significant, inverse relationship with the wetness index and was directly related to vapor pressure deficit. These results have major implications for our understanding of the CO 2 response of ecosystems and for global projections of CO 2 fertilization, because, although direct effects are typically understood and easily reproducible in models, simulations of indirect effects are far more challenging and difficult to constrain. Our findings also provide an explanation for the discrepancies between experiments in the total CO 2 effect on net primary productivity.

Carbon Cycle Model Linkage Project (CCMLP): Evaluating Biogeochemical Process Models with Atmospheric Measurements and Field Experiments

NASA Astrophysics Data System (ADS)

Heimann, M.; Prentice, I. C.; Foley, J.; Hickler, T.; Kicklighter, D. W.; McGuire, A. D.; Melillo, J. M.; Ramankutty, N.; Sitch, S.

2001-12-01

Models of biophysical and biogeochemical proceses are being used -either offline or in coupled climate-carbon cycle (C4) models-to assess climate- and CO2-induced feedbacks on atmospheric CO2. Observations of atmospheric CO2 concentration, and supplementary tracers including O2 concentrations and isotopes, offer unique opportunities to evaluate the large-scale behaviour of models. Global patterns, temporal trends, and interannual variability of the atmospheric CO2 concentration and its seasonal cycle provide crucial benchmarks for simulations of regionally-integrated net ecosystem exchange; flux measurements by eddy correlation allow a far more demanding model test at the ecosystem scale than conventional indicators, such as measurements of annual net primary production; and large-scale manipulations, such as the Duke Forest Free Air Carbon Enrichment (FACE) experiment, give a standard to evaluate modelled phenomena such as ecosystem-level CO2 fertilization. Model runs including historical changes of CO2, climate and land use allow comparison with regional-scale monthly CO2 balances as inferred from atmospheric measurements. Such comparisons are providing grounds for some confidence in current models, while pointing to processes that may still be inadequately treated. Current plans focus on (1) continued benchmarking of land process models against flux measurements across ecosystems and experimental findings on the ecosystem-level effects of enhanced CO2, reactive N inputs and temperature; (2) improved representation of land use, forest management and crop metabolism in models; and (3) a strategy for the evaluation of C4 models in a historical observational context.

Agroecosystem productivity in a warmer and CO2 enriched atmosphere

NASA Astrophysics Data System (ADS)

Bernacchi, Carl; Köhler, Iris; Ort, Donald; Long, Steven; Clemente, Thomas

2017-04-01

A number of in-field manipulative experiments have been conducted that address the response of key ecosystem services of major agronomic species to rising CO2. Global warming, however, is inextricably linked to rising greenhouse gases in general, of which CO2 is the most dominant. Therefore, agroecosystem functioning in future conditions requires an understanding of plant responses to both rising CO2 and increased temperatures. Few in-field manipulative experiments have been conducted that supplement both heating and CO2 above background concentrations. Here, the results of six years of experimentation using a coupled Free Air CO2 Enrichment (FACE) technology with variable output infrared heating arrays are reported. The manipulative experiment increased temperatures (+ 3.5˚ C) and CO2 (+ 200 μmol mol-1) above background levels for on two major agronomic crop species grown throughout the world, Zea mays (maize) and Glycine max (soybean). The first phase of this research addresses the response of plant physiological parameters to growth in elevated CO2 and warmer temperatures for maize and soybean grown in an open-air manipulative experiment. The results show that any increase in ecosystem productivity associated with rising CO2 is either similar or is offset by growth at higher temperatures, inconsistent with the perceived benefits of higher CO2 plus warmer temperatures on agroecosystem productivity. The second phase of this research addresses the opportunity to genetically modify soybean to allow for improved productivity under high CO2 and warmer temperatures by increasing a key photosynthetic carbon reduction cycle enzyme, SPBase. The results from this research demonstrates that manipulation of the photosynthetic pathway can lead to higher productivity in high CO2 and temperature relative to the wild-type control soybean. Overall, this research advances the understanding of the physiological responses of two major crops, and the impact on ecosystem services, to atmospheric conditions with the ultimate goals of better understanding agronomic responses to global change and improved representation of these processes in ecosystem models.

Linkages of plant stoichiometry to ecosystem production and carbon fluxes with increasing nitrogen inputs in an alpine steppe.

PubMed

Peng, Yunfeng; Li, Fei; Zhou, Guoying; Fang, Kai; Zhang, Dianye; Li, Changbin; Yang, Guibiao; Wang, Guanqin; Wang, Jun; Yang, Yuanhe

2017-12-01

Unprecedented levels of nitrogen (N) have entered terrestrial ecosystems over the past century, which substantially influences the carbon (C) exchange between the atmosphere and biosphere. Temperature and moisture are generally regarded as the major controllers over the N effects on ecosystem C uptake and release. N-phosphorous (P) stoichiometry regulates the growth and metabolisms of plants and soil organisms, thereby affecting many ecosystem C processes. However, it remains unclear how the N-induced shift in the plant N:P ratio affects ecosystem production and C fluxes and its relative importance. We conducted a field manipulative experiment with eight N addition levels in a Tibetan alpine steppe and assessed the influences of N on aboveground net primary production (ANPP), gross ecosystem productivity (GEP), ecosystem respiration (ER), and net ecosystem exchange (NEE); we used linear mixed-effects models to further determine the relative contributions of various factors to the N-induced changes in these parameters. Our results showed that the ANPP, GEP, ER, and NEE all exhibited nonlinear responses to increasing N additions. Further analysis demonstrated that the plant N:P ratio played a dominate role in shaping these C exchange processes. There was a positive relationship between the N-induced changes in ANPP (ΔANPP) and the plant N:P ratio (ΔN:P), whereas the ΔGEP, ΔER, and ΔNEE exhibited quadratic correlations with the ΔN:P. In contrast, soil temperature and moisture were only secondary predictors for the changes in ecosystem production and C fluxes along the N addition gradient. These findings highlight the importance of plant N:P ratio in regulating ecosystem C exchange, which is crucial for improving our understanding of C cycles under the scenarios of global N enrichment. © 2017 John Wiley & Sons Ltd.

Different types of interactions of links in artificial and natural ecosystems under anthropogenic pressure

NASA Astrophysics Data System (ADS)

Somova, Lydia; Pisman, Tamara; Mikheeva, Galina; Pechurkin, Nickolay

The life of organisms in an ecosystem depends not only on abiotic factors, but also on the interaction of organisms in which they come with each other. The study of mechanisms of the bioregulation based on ecological - biochemical interactions of ecosystem links is necessary to know the ecosystem development, its stability, survival of ecosystem organisms. It is of high importance as for the creation of artificial ecosystems, and also for the study of natural ecosystems under anthropogenic pressure on them. To create well-functioning ecosystems is necessary to study and consider the basic types of relationships between organisms. The basic types of interactions between organisms have been studied with simple terrestrial and water ecosystems. 1. The interaction of microbiocenoses and plants were studied in experiments with agrocenoses. Microbiocenosis proposed for increase of productivity of plants and for obtaining ecologically pure production of plants has been created taking into account mutual relationships between species of microorganisms. 2. The experimental model of the atmosphere closed «autotroph - heterotroph» system in which heterotrophic link was the mixed population of yeasts (Candida utilis and Candida guilliermondii) was studied. The algae Chlorella vulgaris was used as an autotroph link. It was shown, that the competition result for heterotrophic link depended on strategy of populations of yeast in relation to a substrate and oxygen utilization. 3. As a result of experimental and theoretical modelling of a competition of algae Chlorella vulgaris and Scenedesmus quadricauda at continuous cultivation, the impossibility of their coexistence in the conditions of limitation on nitrogen was shown. 4. Pray-predator interactions between algae (Chlorella vulgaris, Scenedesmus quadricauda) and invertebrates (Paramecium caudatum, Brachionus plicatilis) were studied in experimental closed ecosystem. This work was partly supported by the Russian Foundation for Basic Research, project No.13-06-00060

The response of tropical rainforests to drought-lessons from recent research and future prospects.

PubMed

Bonal, Damien; Burban, Benoit; Stahl, Clément; Wagner, Fabien; Hérault, Bruno

We review the recent findings on the influence of drought on tree mortality, growth or ecosystem functioning in tropical rainforests. Drought plays a major role in shaping tropical rainforests and the response mechanisms are highly diverse and complex. The numerous gaps identified here require the international scientific community to combine efforts in order to conduct comprehensive studies in tropical rainforests on the three continents. These results are essential to simulate the future of these ecosystems under diverse climate scenarios and to predict the future of the global earth carbon balance. Tropical rainforest ecosystems are characterized by high annual rainfall. Nevertheless, rainfall regularly fluctuates during the year and seasonal soil droughts do occur. Over the past decades, a number of extreme droughts have hit tropical rainforests, not only in Amazonia but also in Asia and Africa. The influence of drought events on tree mortality and growth or on ecosystem functioning (carbon and water fluxes) in tropical rainforest ecosystems has been studied intensively, but the response mechanisms are complex. Herein, we review the recent findings related to the response of tropical forest ecosystems to seasonal and extreme droughts and the current knowledge about the future of these ecosystems. This review emphasizes the progress made over recent years and the importance of the studies conducted under extreme drought conditions or in through-fall exclusion experiments in understanding the response of these ecosystems. It also points to the great diversity and complexity of the response of tropical rainforest ecosystems to drought. The numerous gaps identified here require the international scientific community to combine efforts in order to conduct comprehensive studies in tropical forest regions. These results are essential to simulate the future of these ecosystems under diverse climate scenarios and to predict the future of the global earth carbon balance.

Evaluation of 11 terrestrial carbon–nitrogen cycle models against observations from two temperate Free-Air CO2 Enrichment studies

PubMed Central

Zaehle, Sönke; Medlyn, Belinda E; De Kauwe, Martin G; Walker, Anthony P; Dietze, Michael C; Hickler, Thomas; Luo, Yiqi; Wang, Ying-Ping; El-Masri, Bassil; Thornton, Peter; Jain, Atul; Wang, Shusen; Warlind, David; Weng, Ensheng; Parton, William; Iversen, Colleen M; Gallet-Budynek, Anne; McCarthy, Heather; Finzi, Adrien; Hanson, Paul J; Prentice, I Colin; Oren, Ram; Norby, Richard J

2014-01-01

We analysed the responses of 11 ecosystem models to elevated atmospheric [CO2] (eCO2) at two temperate forest ecosystems (Duke and Oak Ridge National Laboratory (ORNL) Free-Air CO2 Enrichment (FACE) experiments) to test alternative representations of carbon (C)–nitrogen (N) cycle processes. We decomposed the model responses into component processes affecting the response to eCO2 and confronted these with observations from the FACE experiments. Most of the models reproduced the observed initial enhancement of net primary production (NPP) at both sites, but none was able to simulate both the sustained 10-yr enhancement at Duke and the declining response at ORNL: models generally showed signs of progressive N limitation as a result of lower than observed plant N uptake. Nonetheless, many models showed qualitative agreement with observed component processes. The results suggest that improved representation of above-ground–below-ground interactions and better constraints on plant stoichiometry are important for a predictive understanding of eCO2 effects. Improved accuracy of soil organic matter inventories is pivotal to reduce uncertainty in the observed C–N budgets. The two FACE experiments are insufficient to fully constrain terrestrial responses to eCO2, given the complexity of factors leading to the observed diverging trends, and the consequential inability of the models to explain these trends. Nevertheless, the ecosystem models were able to capture important features of the experiments, lending some support to their projections. PMID:24467623

Experimental Biodiversity Enrichment in Oil-Palm-Dominated Landscapes in Indonesia.

PubMed

Teuscher, Miriam; Gérard, Anne; Brose, Ulrich; Buchori, Damayanti; Clough, Yann; Ehbrecht, Martin; Hölscher, Dirk; Irawan, Bambang; Sundawati, Leti; Wollni, Meike; Kreft, Holger

2016-01-01

Tropical biodiversity is threatened by the expansion of oil-palm plantations. Reduced-impact farming systems such as agroforests, have been proposed to increase biodiversity and ecosystem functioning. In regions where oil-palm plantations already dominate the landscape, this increase can only be achieved through systematic ecological restoration. However, our knowledge about the underlying ecological and socio-economic processes, constraints, and trade-offs of ecological restoration in oil-palm landscapes is very limited. To bridge this gap, we established a long-term biodiversity enrichment experiment. We established experimental tree islands in a conventional oil-palm plantation and systematically varied plot size, tree diversity, and tree species composition. Here, we describe the rationale and the design of the experiment, the ecosystem variables (soil, topography, canopy openness) and biotic characteristics (associated vegetation, invertebrates, birds) of the experimental site prior to the establishment of the experiment, and initial experimental effects on the fauna. Already one year after establishment of the experiment, tree plantings had an overall positive effect on the bird and invertebrate communities at the plantation scale. The diversity and abundance of invertebrates was positively affected by the size of the tree islands. Based on these results, we expect a further increase of biodiversity and associated ecological functions in the future. The long-term interdisciplinary monitoring of ecosystem variables, flora, fauna, and socio-economic aspects will allow us to evaluate the suitability of tree islands as a restoration measure. Thereof, guidelines for ecologically improved and socio-economically viable restoration and management concepts could be developed.

Calibration and analysis of genome-based models for microbial ecology.

PubMed

Louca, Stilianos; Doebeli, Michael

2015-10-16

Microbial ecosystem modeling is complicated by the large number of unknown parameters and the lack of appropriate calibration tools. Here we present a novel computational framework for modeling microbial ecosystems, which combines genome-based model construction with statistical analysis and calibration to experimental data. Using this framework, we examined the dynamics of a community of Escherichia coli strains that emerged in laboratory evolution experiments, during which an ancestral strain diversified into two coexisting ecotypes. We constructed a microbial community model comprising the ancestral and the evolved strains, which we calibrated using separate monoculture experiments. Simulations reproduced the successional dynamics in the evolution experiments, and pathway activation patterns observed in microarray transcript profiles. Our approach yielded detailed insights into the metabolic processes that drove bacterial diversification, involving acetate cross-feeding and competition for organic carbon and oxygen. Our framework provides a missing link towards a data-driven mechanistic microbial ecology.

Resilience: Concepts and Measures. Chapter 2

NASA Technical Reports Server (NTRS)

Westman, Walter E.

1986-01-01

Inertia, the resistance of an ecosystem property to change under stress, is distinguished from resilience, which refers to the degree, manner. and pace of change or recovery in ecosystem properties following disturbance. In turn, these two terms are differentiated from 'stability'. which is used here to refer to the pattern of natural fluctuation in ecosystem properties in the absence of major exogenous disturbance. Four component attributes of resilience are reviewed in the context of Mediterranean-climate examples. The elasticity component concerns the rate of recovery of an ecosystem property following disturbance; amplitude, the threshold of stress beyond which recovery to the initial state does not occur; hysteresis, the degree to which the pattern of recovery after stress differs from that of deterioration under chronic stress, and malleability the ease with which the ecosystem can become permanently altered. Each ecosystem property will typically reveal a different level of resilience to a given stress and stressor. The degree of recovery should not be expected to be complete in any event, due to sample variability and stochastic events. In cyclicallystable ecosystems, the pattern of recovery should be measured in light of this periodicity, and short-term (within-cycle) recovery distinguished from long-term (between-cycle) recovery. The prediction of resilience properties of ecosystems can be approached through a knowledge of the modular structure of foodwebs, through knowledge of the autecological adaptations of key species to the stressor, or through cumulative experience of the response to disturbance at the community level. At present there is much room for investigation of each of these approaches in Mediterranean-climate ecosystems.

Effects of experimental water table and temperature manipulations on ecosystem CO2 fluxes in an Alaskan rich fen

USGS Publications Warehouse

Chivers, M.R.; Turetsky, M.R.; Waddington, J.M.; Harden, J.W.; McGuire, A.D.

2009-01-01

Peatlands store 30% of the world's terrestrial soil carbon (C) and those located at northern latitudes are expected to experience rapid climate warming. We monitored growing season carbon dioxide (CO2) fluxes across a factorial design of in situ water table (control, drought, and flooded plots) and soil warming (control vs. warming via open top chambers) treatments for 2 years in a rich fen located just outside the Bonanza Creek Experimental Forest in interior Alaska. The drought (lowered water table position) treatment was a weak sink or small source of atmospheric CO2 compared to the moderate atmospheric CO2 sink at our control. This change in net ecosystem exchange was due to lower gross primary production and light-saturated photosynthesis rather than increased ecosystem respiration. The flooded (raised water table position) treatment was a greater CO2 sink in 2006 due largely to increased early season gross primary production and higher light-saturated photosynthesis. Although flooding did not have substantial effects on rates of ecosystem respiration, this water table treatment had lower maximum respiration rates and a higher temperature sensitivity of ecosystem respiration than the control plot. Surface soil warming increased both ecosystem respiration and gross primary production by approximately 16% compared to control (ambient temperature) plots, with no net effect on net ecosystem exchange. Results from this rich fen manipulation suggest that fast responses to drought will include reduced ecosystem C storage driven by plant stress, whereas inundation will increase ecosystem C storage by stimulating plant growth. ?? 2009 Springer Science+Business Media, LLC.

Habitat fragmentation and its lasting impact on Earth’s ecosystems

PubMed Central

Haddad, Nick M.; Brudvig, Lars A.; Clobert, Jean; Davies, Kendi F.; Gonzalez, Andrew; Holt, Robert D.; Lovejoy, Thomas E.; Sexton, Joseph O.; Austin, Mike P.; Collins, Cathy D.; Cook, William M.; Damschen, Ellen I.; Ewers, Robert M.; Foster, Bryan L.; Jenkins, Clinton N.; King, Andrew J.; Laurance, William F.; Levey, Douglas J.; Margules, Chris R.; Melbourne, Brett A.; Nicholls, A. O.; Orrock, John L.; Song, Dan-Xia; Townshend, John R.

2015-01-01

We conducted an analysis of global forest cover to reveal that 70% of remaining forest is within 1 km of the forest’s edge, subject to the degrading effects of fragmentation. A synthesis of fragmentation experiments spanning multiple biomes and scales, five continents, and 35 years demonstrates that habitat fragmentation reduces biodiversity by 13 to 75% and impairs key ecosystem functions by decreasing biomass and altering nutrient cycles. Effects are greatest in the smallest and most isolated fragments, and they magnify with the passage of time. These findings indicate an urgent need for conservation and restoration measures to improve landscape connectivity, which will reduce extinction rates and help maintain ecosystem services. PMID:26601154

Tipping points in the arctic: eyeballing or statistical significance?

PubMed

Carstensen, Jacob; Weydmann, Agata

2012-02-01

Arctic ecosystems have experienced and are projected to experience continued large increases in temperature and declines in sea ice cover. It has been hypothesized that small changes in ecosystem drivers can fundamentally alter ecosystem functioning, and that this might be particularly pronounced for Arctic ecosystems. We present a suite of simple statistical analyses to identify changes in the statistical properties of data, emphasizing that changes in the standard error should be considered in addition to changes in mean properties. The methods are exemplified using sea ice extent, and suggest that the loss rate of sea ice accelerated by factor of ~5 in 1996, as reported in other studies, but increases in random fluctuations, as an early warning signal, were observed already in 1990. We recommend to employ the proposed methods more systematically for analyzing tipping points to document effects of climate change in the Arctic.

Biogeochemical Responses and Feedbacks to Climate Change: Synthetic Meta-Analyses Relevant to Earth System Models

DOE Office of Scientific and Technical Information (OSTI.GOV)

van Gestel, Natasja; Jan van Groenigen, Kees; Osenberg, Craig

This project examined the sensitivity of carbon in land ecosystems to environmental change, focusing on carbon contained in soil, and the role of carbon-nitrogen interactions in regulating ecosystem carbon storage. The project used a combination of empirical measurements, mathematical models, and statistics to partition effects of climate change on soil into processes enhancing soil carbon and processes through which it decomposes. By synthesizing results from experiments around the world, the work provided novel insight on ecological controls and responses across broad spatial and temporal scales. The project developed new approaches in meta-analysis using principles of element mass balance and largemore » datasets to derive metrics of ecosystem responses to environmental change. The project used meta-analysis to test how nutrients regulate responses of ecosystems to elevated CO2 and warming, in particular responses of nitrogen fixation, critical for regulating long-term C balance.« less

Mechanistic insights on the responses of plant and ecosystem gas exchange to global environmental change: lessons from Biosphere 2.

PubMed

Gonzalez-Meler, Miquel A; Rucks, Jessica S; Aubanell, Gerard

2014-09-01

Scaling up leaf processes to canopy/ecosystem level fluxes is critical for examining feedbacks between vegetation and climate. Collectively, studies from Biosphere 2 Laboratory have provided important insight of leaf-to-ecosystem investigations of multiple environmental parameters that were not before possible in enclosed or field studies. B2L has been a testing lab for the applicability of new technologies such as spectral approaches to detect spatial and temporal changes in photosynthesis within canopies, or for the development of cavity ring-down isotope applications for ecosystem evapotranspiration. Short and long term changes in atmospheric CO2, drought or temperature allowed for intensive investigation of the interactions between photosynthesis and leaf, soil and ecosystem respiration. Experiments conducted in the rainforest biome have provided some of the most comprehensive dataset to date on the effects of climate change variables on tropical ecosystems. Results from these studies have been later corroborated in natural rainforest ecosystems and have improved the predictive capabilities of models that now show increased resilience of tropics to climate change. Studies of temperature and CO2 effects on ecosystem respiration and its leaf and soil components have helped reconsider the use of simple first-order kinetics for characterizing respiration in models. The B2L also provided opportunities to quantify the rhizosphere priming effect, or establish the relationships between net primary productivity, atmospheric CO2 and isoprene emissions. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Using a Multi-Method Approach to Examine Social-Ecological Vulnerability to Climate Change and Natural Resource Policies on the Tibetan Plateau

NASA Astrophysics Data System (ADS)

Klein, J.; Hopping, K. A.; Yeh, E.; Nyima, Y.; Galvin, K.; Boone, R.; Dorje, T.; Ojima, D. S.

2012-12-01

Pastoralists and ecosystems on the Tibetan Plateau are facing a suite of novel stresses. Temperatures are increasing several times more than the global average. The frequency and severity of severe snowstorms, which lead to critical losses of livestock, are also increasing. Pastoralists are also experiencing changes to their livelihood activities, including reduced mobility and severe grazing restrictions. We are using interdisciplinary frameworks and methods that integrate results from a multifactor ecological experiment, household interviews, remote sensing, and a coupled ecosystem and household decision-making model to examine herder and ecosystem vulnerability to climate change and extreme weather events (snow disasters) within the context of changing natural resource management policies in China. The fully factorial ecological experiment includes two climate changes (warming and spring snow additions) and two types of grazing (yak and pika) that are being affected by current policy. We established the experiment in 2008 within the Tibet Autonomous Region. We are monitoring microclimate, vegetation, nutrient availability, ecosystem carbon fluxes and stable isotope signatures of select plant species. Through this experiment, we are investigating the sensitivity of the system, whether it can cross critical thresholds, and how resilient this system may be to predicted future climate and land use changes. Semi-structured, in-depth interviews on indigenous knowledge and vulnerability complement the ecological experimental work. We are asking herders about climate and ecological change and their drivers and are also conducting interviews on vulnerability to snow disasters across a three site, 300-500mm precipitation gradient. We are using remote sensing to identify biophysical landscape change over time. To integrate our ecological and social findings, we are coupling the Savanna ecosystem model to the DECUMA agent-based pastoral household model. Our results to date from the experiment and the indigenous knowledge study suggest that Kobresia pygmaea, the dominant plant species and the primary grazing resource, is vulnerable to warming. Moreover, several lines of evidence suggest that warming is causing delayed spring phenology, with important ecosystem and livelihood implications. Herders are observing climatic and ecological changes, knowledge which is important for adaptation, but people whose livelihoods are most directly derived from the rangelands, those situated at higher elevations, and those who are more mobile across the landscape are most attuned to these changes. These results suggest that rangeland degradation and delayed spring phenology are occurring, and that climate warming may be responsible for these changes. While additional snow may improve ecological conditions, the warming-induced degradation may make the social-ecological system more vulnerable to large snowstorm events. Our findings suggest that climate adaptation strategies should address the effects of both climate warming and the changing nature of extreme weather events and should also encourage land use policies that will maintain these systems under change. Moreover, policies that encourage mobility and rangeland-based livelihoods will enhance adaptation to climate change.

Application of lime (CaCO3) to promote forest recovery from severe acidification increases potential for earthworm invasion

USGS Publications Warehouse

Homan, Caitlin; Beirer, Colin M; McCay, Timothy S; Lawrence, Gregory B.

2016-01-01

The application of lime (calcium carbonate) may be a cost-effective strategy to promote forest ecosystem recovery from acid impairment, under contemporary low levels of acidic deposition. However, liming acidified soils may create more suitable habitat for invasive earthworms that cause significant damage to forest floor communities and may disrupt ecosystem processes. We investigated the potential effects of liming in acidified soils where earthworms are rare in conjunction with a whole-ecosystem liming experiment in the chronically acidified forests of the western Adirondacks (USA). Using a microcosm experiment that replicated the whole-ecosystem treatment, we evaluated effects of soil liming on Lumbricus terrestris survivorship and biomass growth. We found that a moderate lime application (raising pH from 3.1 to 3.7) dramatically increased survival and biomass of L. terrestris, likely via increases in soil pH and associated reductions in inorganic aluminum, a known toxin. Very few L. terrestris individuals survived in unlimed soils, whereas earthworms in limed soils survived, grew, and rapidly consumed leaf litter. We supplemented this experiment with field surveys of extant earthworm communities along a gradient of soil pH in Adirondack hardwood forests, ranging from severely acidified (pH < 3) to well-buffered (pH > 5). In the field, no earthworms were observed where soil pH < 3.6. Abundance and species richness of earthworms was greatest in areas where soil pH > 4.4 and human dispersal vectors, including proximity to roads and public fishing access, were most prevalent. Overall our results suggest that moderate lime additions can be sufficient to increase earthworm invasion risk where dispersal vectors are present.

Meta-analysis of high-latitude nitrogen-addition and warming studies imply ecological mechanisms overlooked by land models

NASA Astrophysics Data System (ADS)

Bouskill, N. J.; Riley, W. J.; Tang, J.

2014-08-01

Accurate representation of ecosystem processes in land models is crucial for reducing predictive uncertainty in energy and greenhouse gas feedbacks with the atmosphere. Here we describe an observational and modeling meta-analysis approach to benchmark land models, and apply the method to the land model CLM4.5 with two versions of belowground biogeochemistry. We focused our analysis on the above and belowground high-latitude ecosystem responses to warming and nitrogen addition, and identified mechanisms absent, or poorly parameterized in CLM4.5. While the two model versions predicted similar trajectories for soil carbon stocks following both types of perturbation, other variables (e.g., belowground respiration) differed from the observations in both magnitude and direction, indicating the underlying mechanisms are inadequate for representing high-latitude ecosystems. The observational synthesis attribute these differences to missing representations of microbial dynamics, characterization of above and belowground functional processes, and nutrient competition. We use the observational meta-analyses to discuss potential approaches to improving the current models (e.g., the inclusion of dynamic vegetation or different microbial functional guilds), however, we also raise a cautionary note on the selection of data sets and experiments to be included in a meta-analysis. For example, the concentrations of nitrogen applied in the synthesized field experiments (average =72 kg ha-1 yr-1) are many times higher than projected soil nitrogen concentrations (from nitrogen deposition and release during mineralization), which preclude a rigorous evaluation of the model responses to nitrogen perturbation. Overall, we demonstrate here that elucidating ecological mechanisms via meta-analysis can identify deficiencies in both ecosystem models and empirical experiments.

Meta-analysis of high-latitude nitrogen-addition and warming studies imply ecological mechanisms overlooked by land models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bouskill, N. J.; Riley, W. J.; Tang, J.

2014-08-18

Accurate representation of ecosystem processes in land models is crucial for reducing predictive uncertainty in energy and greenhouse gas feedbacks with the atmosphere. Here we describe an observational and modeling meta-analysis approach to benchmark land models, and apply the method to the land model CLM4.5 with two versions of belowground biogeochemistry. We focused our analysis on the above and belowground high-latitude ecosystem responses to warming and nitrogen addition, and identified mechanisms absent, or poorly parameterized in CLM4.5. While the two model versions predicted similar trajectories for soil carbon stocks following both types of perturbation, other variables (e.g., belowground respiration) differedmore » from the observations in both magnitude and direction, indicating the underlying mechanisms are inadequate for representing high-latitude ecosystems. The observational synthesis attribute these differences to missing representations of microbial dynamics, characterization of above and belowground functional processes, and nutrient competition. We use the observational meta-analyses to discuss potential approaches to improving the current models (e.g., the inclusion of dynamic vegetation or different microbial functional guilds), however, we also raise a cautionary note on the selection of data sets and experiments to be included in a meta-analysis. For example, the concentrations of nitrogen applied in the synthesized field experiments (average =72 kg ha -1 yr -1) are many times higher than projected soil nitrogen concentrations (from nitrogen deposition and release during mineralization), which preclude a rigorous evaluation of the model responses to nitrogen perturbation. Overall, we demonstrate here that elucidating ecological mechanisms via meta-analysis can identify deficiencies in both ecosystem models and empirical experiments.« less

Rapid evolution mitigates the ecological consequences of an invasive species (Bythotrephes longimanus) in lakes in Wisconsin.

PubMed

Gillis, Michael K; Walsh, Matthew R

2017-07-12

Invasive species have extensive negative consequences for biodiversity and ecosystem health. Novel species also drive contemporary evolution in many native populations, which could mitigate or amplify their impacts on ecosystems. The predatory zooplankton Bythotrephes longimanus invaded lakes in Wisconsin, USA, in 2009. This invasion caused precipitous declines in zooplankton prey ( Daphnia pulicaria ), with cascading impacts on ecosystem services (water clarity). Here, we tested the link between Bythotrephes invasion, evolution in Daphnia and post-invasion ecological dynamics using 15 years of long-term data in conjunction with comparative experiments. Invasion by Bythotrephes is associated with rapid increases in the body size of Daphnia Laboratory experiments revealed that such shifts have a genetic component; third-generation laboratory-reared Daphnia from 'invaded' lakes are significantly larger and exhibit greater reproductive effort than individuals from 'uninvaded' lakes. This trajectory of evolution should accelerate Daphnia population growth and enhance population persistence. We tested this prediction by comparing analyses of long-term data with laboratory-based simulations, and show that rapid evolution in Daphnia is associated with increased population growth in invaded lakes. © 2017 The Authors.

The Effect of Increased CO2 Mixing Ratio on Water Use Efficiency, Evapo-transpiration, Soil Moisture Content and Stem Flow in two Long-term Field Experiments

NASA Astrophysics Data System (ADS)

Drake, B.; Powell, T.; Li, J.; Hinkle, R.; Rasse, D.

2007-12-01

Stomatal opening in plant leaves control carbon and water exchange between vegetation and the atmosphere. Closure of these water-gates in response to increased atmospheric CO2 mixing ratio's, reduces transpiration under most laboratory and short term experimental conditions. Does this imply however, as atmospheric CO2 rises, and plant canopies expand, that evapo-transpiration (ETR), soil moisture content (SMC), and ecosystem water use efficiency (WUE) will increase? To test this question, field experiments have been and still are conducted using open top chambers. We have exposed native species in Florida Scrub to a carbon dioxide mixing ratio of nearly 700 ppmv CO2 for the past ten years and in Chesapeake Bay wetlands for 21 years. As a result of this treatment, in both ecosystems there was an increase in net ecosystem CO2 exchange and leaf area but a reduction of stomatal conductance, stem flow, transpiration, and ETR. For Florida scrub oak, these changes were also accompanied by an increase in soil moisture content as well.

Stable isotope probing to study functional components of complex microbial ecosystems.

PubMed

Mazard, Sophie; Schäfer, Hendrik

2014-01-01

This protocol presents a method of dissecting the DNA or RNA of key organisms involved in a specific biochemical process within a complex ecosystem. Stable isotope probing (SIP) allows the labelling and separation of nucleic acids from community members that are involved in important biochemical transformations, yet are often not the most numerically abundant members of a community. This pure culture-independent technique circumvents limitations of traditional microbial isolation techniques or data mining from large-scale whole-community metagenomic studies to tease out the identities and genomic repertoires of microorganisms participating in biological nutrient cycles. SIP experiments can be applied to virtually any ecosystem and biochemical pathway under investigation provided a suitable stable isotope substrate is available. This versatile methodology allows a wide range of analyses to be performed, from fatty-acid analyses, community structure and ecology studies, and targeted metagenomics involving nucleic acid sequencing. SIP experiments provide an effective alternative to large-scale whole-community metagenomic studies by specifically targeting the organisms or biochemical transformations of interest, thereby reducing the sequencing effort and time-consuming bioinformatics analyses of large datasets.

Throughfall Displacement Experiment (TDE) Ecosystem Model Intercomparison Project Data Archive

DOE Data Explorer

Hanson, Paul J. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (USA); Amthor, Jeffrey S. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (USA); Baldocchi, Dennis D. [University of California, Berkeley; Grant, Robert F. [University of Alberta, Canada; Hartley, Anne E. [Ohio State University; Hui, Dafeng [University of Oklahoma; Hunt, Jr., E. Raymond [Agricultural Research Service, U.S. Department of Agriculture; Johnson, Dale W. [University of Nevada, Reno; Kimball, John S. [University of Montana; King, Anthony W. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (USA); Luo, Yiqi [University of Oklahoma; McNulty, Steven G. [Southern Global Change Program, U.S. Forest Service, U.S. Department of Agriculture; Sun, Ge [North Carolina State University, Raleigh, NC (USA); Thornton, Peter E. [University of Montana; Wang, Shusen [Geomatics Canada - Canada Centre for Remote Sensing Natural Resources, Canada; Williams, Matthew [University of Edinburgh, United Kingdom; Wilson, Kell B. [National Oceanic and Atmospheric Administration, U.S. Department of Commerce; Wullschleger, Stanley D. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (USA)

2002-08-01

This archive provides and documents data from a project whose purpose is to compare the output of various ecosystem models when they are run with the data from the Throughfall Displacement Experiment (TDE) at Walker Branch Watershed, Oak Ridge, Tennessee. The project is not designed to determine which models are "best" for diagnosis (i.e., explaining the current functioning of the system) or prognosis (i.e., predicting the response of the system to future conditions), but, rather, to clarify similarities and differences among the models and their components, so that all models can be improved. Data archive: ftp://cdiac.ornl.gov/ftp/tdemodel/. TDE data archive web site: http://cdiac.ess-dive.lbl.gov/epubs/ndp/ndp078a/ndp078a.html.

The Effects of Decomposition on the Oxidative Ratio and Carbon Oxidation State of Organic Matter

NASA Astrophysics Data System (ADS)

Gallagher, M. E.; Masiello, C. A.; Clark, N.; Randerson, J. T.; Robertson, G. P.

2006-12-01

Ecosystem oxidative ratio (OR) and the related parameter carbon oxidation state (Cox) are critical in the apportionment of anthropogenic CO2 between the terrestrial biosphere and ocean reservoirs. OR is the ratio of O2 to CO2 in gas exchange fluxes between the biosphere and the atmosphere (Fba and Fab). Accurate measurements of OR have been challenging (Seibt et al. 2004); instead we approach the problem by measuring Cox and calculating OR from biomass reservoirs. Cox can range from -4 to +4 (CH4 to CO2) and is driven by photosynthesis, respiration, and decomposition. The net OR of the biosphere varies with ecosystem type, and this can affect the apportionment of anthropogenic CO2 between the terrestrial biosphere and ocean reservoirs (Randerson et al. 2006). This makes it essential to constrain ecosystem Cox and OR values. Although small variations in global ecosystem OR have the potential to cause shifts in atmospheric O2 concentrations, no whole ecosystem measurements of Cox yet exist. To constrain ORba and ORab, and improve our understanding of how decomposition affects Cox, we performed a litter bag experiment at the Kellogg Biological Station-Long Term Ecological Research (KBS-LTER) in Michigan at the end of the 2005 agricultural season. We placed 15 corn biomass litter bags in an agricultural field and collected 3 bags at 2, 4, 7, 26, and 29 weeks. These samples were analyzed for %C, %H, %N, and %O via elemental analysis, and these data were used to calculate Cox. Aboveground Cox was measured similarly. We anticipated that the Cox of the corn litter would become more reduced with decomposition, as the percentage of carbohydrates would decrease with time, while that of protein, lignin, and lipids would increase (Baldock et al. 2004). We report differences between the Cox of biomass fixation and biomass degradation from our experiments. Using simple assumptions about ecosystem nitrogen cycling, we convert Cox to OR and report the existence or absence of a temporal offset between ORab and ORba within an agricultural ecosystem.

Drought and resprouting plants

DOE PAGES

Zeppel, Melanie J. B.; Harrison, Sandy P.; Adams, Henry D.; ...

2014-12-17

Many species have the ability to resprout vegetatively after a substantial loss of biomass induced by environmental stress, including drought. Many of the regions characterised by ecosystems where resprouting is common are projected to experience more frequent and intense drought during the 21 st century. However, in assessments of ecosystem response to drought disturbance there has been scant consideration of the resilience and post-drought recovery of resprouting species. Systematic differences in hydraulic and allocation traits suggest that resprouting species are more resilient to drought-stress than nonresprouting species. Evidence suggests that ecosystems dominated by resprouters recover from disturbance more quickly thanmore » ecosystems dominated by nonresprouters. The ability of resprouters to avoid mortality and withstand drought, coupled with their ability to recover rapidly, suggests that the impact of increased drought stress in ecosystems dominated by these species may be small. Furthermore, the strategy of resprouting needs to be modelled explicitly to improve estimates of future climate-change impacts on the carbon cycle, but this will require several important knowledge gaps to be filled before resprouting can be properly implemented.« less

Drought and resprouting plants.

PubMed

Zeppel, Melanie J B; Harrison, Sandy P; Adams, Henry D; Kelley, Douglas I; Li, Guangqi; Tissue, David T; Dawson, Todd E; Fensham, Rod; Medlyn, Belinda E; Palmer, Anthony; West, Adam G; McDowell, Nate G

2015-04-01

Many species have the ability to resprout vegetatively after a substantial loss of biomass induced by environmental stress, including drought. Many of the regions characterised by ecosystems where resprouting is common are projected to experience more frequent and intense drought during the 21st Century. However, in assessments of ecosystem response to drought disturbance there has been scant consideration of the resilience and post-drought recovery of resprouting species. Systematic differences in hydraulic and allocation traits suggest that resprouting species are more resilient to drought-stress than nonresprouting species. Evidence suggests that ecosystems dominated by resprouters recover from disturbance more quickly than ecosystems dominated by nonresprouters. The ability of resprouters to avoid mortality and withstand drought, coupled with their ability to recover rapidly, suggests that the impact of increased drought stress in ecosystems dominated by these species may be small. The strategy of resprouting needs to be modelled explicitly to improve estimates of future climate-change impacts on the carbon cycle, but this will require several important knowledge gaps to be filled before resprouting can be properly implemented. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.

Biotic homogenization can decrease landscape-scale forest multifunctionality.

PubMed

van der Plas, Fons; Manning, Pete; Soliveres, Santiago; Allan, Eric; Scherer-Lorenzen, Michael; Verheyen, Kris; Wirth, Christian; Zavala, Miguel A; Ampoorter, Evy; Baeten, Lander; Barbaro, Luc; Bauhus, Jürgen; Benavides, Raquel; Benneter, Adam; Bonal, Damien; Bouriaud, Olivier; Bruelheide, Helge; Bussotti, Filippo; Carnol, Monique; Castagneyrol, Bastien; Charbonnier, Yohan; Coomes, David Anthony; Coppi, Andrea; Bastias, Cristina C; Dawud, Seid Muhie; De Wandeler, Hans; Domisch, Timo; Finér, Leena; Gessler, Arthur; Granier, André; Grossiord, Charlotte; Guyot, Virginie; Hättenschwiler, Stephan; Jactel, Hervé; Jaroszewicz, Bogdan; Joly, François-Xavier; Jucker, Tommaso; Koricheva, Julia; Milligan, Harriet; Mueller, Sandra; Muys, Bart; Nguyen, Diem; Pollastrini, Martina; Ratcliffe, Sophia; Raulund-Rasmussen, Karsten; Selvi, Federico; Stenlid, Jan; Valladares, Fernando; Vesterdal, Lars; Zielínski, Dawid; Fischer, Markus

2016-03-29

Many experiments have shown that local biodiversity loss impairs the ability of ecosystems to maintain multiple ecosystem functions at high levels (multifunctionality). In contrast, the role of biodiversity in driving ecosystem multifunctionality at landscape scales remains unresolved. We used a comprehensive pan-European dataset, including 16 ecosystem functions measured in 209 forest plots across six European countries, and performed simulations to investigate how local plot-scale richness of tree species (α-diversity) and their turnover between plots (β-diversity) are related to landscape-scale multifunctionality. After accounting for variation in environmental conditions, we found that relationships between α-diversity and landscape-scale multifunctionality varied from positive to negative depending on the multifunctionality metric used. In contrast, when significant, relationships between β-diversity and landscape-scale multifunctionality were always positive, because a high spatial turnover in species composition was closely related to a high spatial turnover in functions that were supported at high levels. Our findings have major implications for forest management and indicate that biotic homogenization can have previously unrecognized and negative consequences for large-scale ecosystem multifunctionality.

Biotic homogenization can decrease landscape-scale forest multifunctionality

PubMed Central

van der Plas, Fons; Manning, Pete; Soliveres, Santiago; Allan, Eric; Scherer-Lorenzen, Michael; Verheyen, Kris; Wirth, Christian; Zavala, Miguel A.; Ampoorter, Evy; Baeten, Lander; Barbaro, Luc; Bauhus, Jürgen; Benavides, Raquel; Benneter, Adam; Bonal, Damien; Bouriaud, Olivier; Bruelheide, Helge; Bussotti, Filippo; Carnol, Monique; Castagneyrol, Bastien; Charbonnier, Yohan; Coppi, Andrea; Bastias, Cristina C.; Dawud, Seid Muhie; De Wandeler, Hans; Domisch, Timo; Finér, Leena; Granier, André; Grossiord, Charlotte; Guyot, Virginie; Hättenschwiler, Stephan; Jactel, Hervé; Jaroszewicz, Bogdan; Joly, François-xavier; Jucker, Tommaso; Koricheva, Julia; Milligan, Harriet; Mueller, Sandra; Muys, Bart; Nguyen, Diem; Pollastrini, Martina; Ratcliffe, Sophia; Raulund-Rasmussen, Karsten; Selvi, Federico; Stenlid, Jan; Valladares, Fernando; Vesterdal, Lars; Zielínski, Dawid; Fischer, Markus

2016-01-01

Many experiments have shown that local biodiversity loss impairs the ability of ecosystems to maintain multiple ecosystem functions at high levels (multifunctionality). In contrast, the role of biodiversity in driving ecosystem multifunctionality at landscape scales remains unresolved. We used a comprehensive pan-European dataset, including 16 ecosystem functions measured in 209 forest plots across six European countries, and performed simulations to investigate how local plot-scale richness of tree species (α-diversity) and their turnover between plots (β-diversity) are related to landscape-scale multifunctionality. After accounting for variation in environmental conditions, we found that relationships between α-diversity and landscape-scale multifunctionality varied from positive to negative depending on the multifunctionality metric used. In contrast, when significant, relationships between β-diversity and landscape-scale multifunctionality were always positive, because a high spatial turnover in species composition was closely related to a high spatial turnover in functions that were supported at high levels. Our findings have major implications for forest management and indicate that biotic homogenization can have previously unrecognized and negative consequences for large-scale ecosystem multifunctionality. PMID:26979952

Herbivory Network: An international, collaborative effort to study herbivory in Arctic and alpine ecosystems

NASA Astrophysics Data System (ADS)

Barrio, I. C.; Hik, D. S.; Jónsdóttir, I. S.; Bueno, C. G.; Mörsdorf, M. A.; Ravolainen, V. T.

2016-09-01

Plant-herbivore interactions are central to the functioning of tundra ecosystems, but their outcomes vary over space and time. Accurate forecasting of ecosystem responses to ongoing environmental changes requires a better understanding of the processes responsible for this heterogeneity. To effectively address this complexity at a global scale, coordinated research efforts, including multi-site comparisons within and across disciplines, are needed. The Herbivory Network was established as a forum for researchers from Arctic and alpine regions to collaboratively investigate the multifunctional role of herbivores in these changing ecosystems. One of the priorities is to integrate sites, methodologies, and metrics used in previous work, to develop a set of common protocols and design long-term geographically-balanced, coordinated experiments. The implementation of these collaborative research efforts will also improve our understanding of traditional human-managed systems that encompass significant portions of the sub-Arctic and alpine areas worldwide. A deeper understanding of the role of herbivory in these systems under ongoing environmental changes will guide appropriate adaptive strategies to preserve their natural values and related ecosystem services.

Biogeochemical and biological impacts of diazotroph blooms in a low-nutrient, low-chlorophyll ecosystem: synthesis from the VAHINE mesocosm experiment (New Caledonia)

NASA Astrophysics Data System (ADS)

Bonnet, Sophie; Baklouti, Melika; Gimenez, Audrey; Berthelot, Hugo; Berman-Frank, Ilana

2016-08-01

In marine ecosystems, biological N2 fixation provides the predominant external source of nitrogen (N; 140 ± 50 Tg N yr-1), contributing more than atmospheric and riverine inputs to the N supply. Yet the fate and magnitude of the newly fixed N, or diazotroph-derived N (hereafter named DDN) in marine ecosystems is poorly understood. Moreover, whether the DDN is preferentially and directly exported out of the photic zone, recycled by the microbial loop and/or transferred into larger organisms remains unclear. These questions were investigated in the framework of the VAHINE (VAriability of vertical and tropHIc transfer of diazotroph derived N in the south wEst Pacific) project. Triplicate large volume ( ˜ 50 m3) mesocosms were deployed in the tropical south-west Pacific coastal ocean (New Caledonia). The mesocosms were intentionally fertilized with ˜ 0.8 µM dissolved inorganic phosphorus (DIP) at the start of the experiment to stimulate diazotrophy. A total of 47 stocks, fluxes, enzymatic activities and diversity parameters were measured daily inside and outside the mesocosms by the 40 scientists involved in the project. The experiment lasted for 23 days and was characterized by two distinct and successive diazotroph blooms: a dominance of diatom-diazotroph associations (DDAs) during the first half of the experiment (days 2-14) followed by a bloom of unicellular cyanobacterial lineage C (UCYN-C during the second half of the experiment (days 15-23). These conditions provided a unique opportunity to compare the DDN transfer and export efficiency associated with different diazotrophs. Here we summarize the major experimental and modelling results obtained during the project and described in the VAHINE special issue, in particular those regarding the evolution of the main standing stocks, fluxes and biological characteristics over the 23-day experiment, the contribution of N2 fixation to export fluxes, the DDN released to dissolved pool and its transfer to the planktonic food web (bacteria, phytoplankton, zooplankton). We then apply our Eco3M modelling platform to further infer the fate of DDN in the ecosystem and the role of N2 fixation on productivity, food web structure and carbon export. Recommendations for future work are finally provided in the conclusion section.

Integrating watershed hydrology and economics to establish a local market for water quality improvement: A field experiment

EPA Science Inventory

Innovative market mechanisms are being increasingly recognized as effective decision-making institutions to incorporate the value of ecosystem services into the economy. We present a field experiment that integrates an economic auction and a biophysical water flux model to develo...

'Trophic whales' as biotic buffers: weak interactions stabilize ecosystems against nutrient enrichment.

PubMed

Schwarzmüller, Florian; Eisenhauer, Nico; Brose, Ulrich

2015-05-01

Human activities may compromise biodiversity if external stressors such as nutrient enrichment endanger overall network stability by inducing unstable dynamics. However, some ecosystems maintain relatively high diversity levels despite experiencing continuing disturbances. This indicates that some intrinsic properties prevent unstable dynamics and resulting extinctions. Identifying these 'ecosystem buffers' is crucial for our understanding of the stability of ecosystems and an important tool for environmental and conservation biologists. In this vein, weak interactions have been suggested as stabilizing elements of complex systems, but their relevance has rarely been tested experimentally. Here, using network and allometric theory, we present a novel concept for a priori identification of species that buffer against externally induced instability of increased population oscillations via weak interactions. We tested our model in a microcosm experiment using a soil food-web motif. Our results show that large-bodied species feeding at the food web's base, so called 'trophic whales', can buffer ecosystems against unstable dynamics induced by nutrient enrichment. Similar to the functionality of chemical or mechanical buffers, they serve as 'biotic buffers' that take up stressor effects and thus protect fragile systems from instability. We discuss trophic whales as common functional building blocks across ecosystems. Considering increasing stressor effects under anthropogenic global change, conservation of these network-intrinsic biotic buffers may help maintain the stability and diversity of natural ecosystems. © 2014 The Authors. Journal of Animal Ecology © 2014 British Ecological Society.

Ecosystem productivity is associated with bacterial phylogenetic distance in surface marine waters.

PubMed

Galand, Pierre E; Salter, Ian; Kalenitchenko, Dimitri

2015-12-01

Understanding the link between community diversity and ecosystem function is a fundamental aspect of ecology. Systematic losses in biodiversity are widely acknowledged but the impact this may exert on ecosystem functioning remains ambiguous. There is growing evidence of a positive relationship between species richness and ecosystem productivity for terrestrial macro-organisms, but similar links for marine micro-organisms, which help drive global climate, are unclear. Community manipulation experiments show both positive and negative relationships for microbes. These previous studies rely, however, on artificial communities and any links between the full diversity of active bacterial communities in the environment, their phylogenetic relatedness and ecosystem function remain hitherto unexplored. Here, we test the hypothesis that productivity is associated with diversity in the metabolically active fraction of microbial communities. We show in natural assemblages of active bacteria that communities containing more distantly related members were associated with higher bacterial production. The positive phylogenetic diversity-productivity relationship was independent of community diversity calculated as the Shannon index. From our long-term (7-year) survey of surface marine bacterial communities, we also found that similarly, productive communities had greater phylogenetic similarity to each other, further suggesting that the traits of active bacteria are an important predictor of ecosystem productivity. Our findings demonstrate that the evolutionary history of the active fraction of a microbial community is critical for understanding their role in ecosystem functioning. © 2015 John Wiley & Sons Ltd.

Exceeding peatland ecohydrological resilience through compound disturbance: the effect of wildfire and drainage

NASA Astrophysics Data System (ADS)

Waddington, J. M.; Kettridge, N.; Sherwood, J.; Thompson, D.; Morris, P. J.

2012-12-01

Peatlands are self-regulating ecosystems dominated by negative ecohydrological feedbacks that stabilize their net carbon sink function, producing a globally significant carbon store that is often resilient to disturbances such as drainage and wildfire. However, the effects of these disturbances on peatland ecohydrological function have only been considered previously in isolation. We capitalize on a unique long-term experiment to examine the response of a peatland in boreal western Canada to the compound disturbance of drying and wildfire. We show that the compound effect of such disturbances can reduce the ecohydrological resilience of these ecosystems leaving them vulnerable to irreversible shifts in their ecological, hydrological and biogeochemical function. Peatland ecosystems have a hydrology characterized generally by a long water residence times and a high water table position. Less-dense near-surface peat acts as a hydrological buffer, regulating water-table position and near-surface moisture content. This buffer is lost through combustion and compaction, increasing the flashiness of the peatland hydrology, increasing the vulnerability of the ecosystem to drought conditions. This greatly reduces the recolonization success of keystone Sphagnum moss species. As a result the peatland followed a previously unobserved development trajectory leading to the loss of globally important ecosystem services and the development of a novel 'peat forest' ecosystem. This ecosystem shift is self-reinforcing, as the establishment of invasive species reduces available light essential for Sphagnum establishment.

Effects of harvesting forest biomass on water and climate regulation services: A synthesis of long-term ecosystem experiments in eastern North America

USGS Publications Warehouse

Caputo, Jesse; Beier, Colin D; Groffman, Peter M; Burns, Douglas A.; Beall, Frederick D; Hazlett, Paul W.; Yorks, Thad E

2016-01-01

Demand for woody biomass fuels is increasing amidst concerns about global energy security and climate change, but there may be negative implications of increased harvesting for forest ecosystem functions and their benefits to society (ecosystem services). Using new methods for assessing ecosystem services based on long-term experimental research, post-harvest changes in ten potential benefits were assessed for ten first-order northern hardwood forest watersheds at three long-term experimental research sites in northeastern North America. As expected, we observed near-term tradeoffs between biomass provision and greenhouse gas regulation, as well as tradeoffs between intensive harvest and the capacity of the forest to remediate nutrient pollution. In both cases, service provision began to recover along with the regeneration of forest vegetation; in the case of pollution remediation, the service recovered to pre-harvest levels within 10 years. By contrast to these two services, biomass harvesting had relatively nominal and transient impacts on other ecosystem services. Our results are sensitive to empirical definitions of societal demand, including methods for scaling societal demand to ecosystem units, which are often poorly resolved. Reducing uncertainty around these parameters can improve confidence in our results and increase their relevance for decision-making. Our synthesis of long-term experimental studies provides insights on the social-ecological resilience of managed forest ecosystems to multiple drivers of change.

Disturbance, complexity, and succession of net ecosystem production in North America’s temperate deciduous forests

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gough, Christopher; Curtis, Peter; Hardiman, Brady

Century-old forests in the U.S. upper Midwest and Northeast power much of North Amer- ica’s terrestrial carbon (C) sink, but these forests’ production and C sequestration capacity are expected to soon decline as fast-growing early successional species die and are replaced by slower growing late successional species. But will this really happen? Here we marshal empirical data and ecological theory to argue that substantial declines in net ecosystem production (NEP) owing to reduced forest growth, or net primary production (NPP), are not imminent in regrown temperate deciduous forests over the next several decades. Forest age and production data for temperatemore » deciduous forests, synthesized from published literature, suggest slight declines in NEP and increasing or stable NPP during middle successional stages. We revisit long-held hypotheses by EP Odum and others that suggest low-severity, high-frequency disturbances occurring in the region’s aging forests will, against intuition, maintain NEP at higher-than- expected rates by increasing ecosystem complexity, sustaining or enhancing NPP to a level that largely o sets rising C losses as heterotrophic respiration increases. This theoretical model is also supported by biological evidence and observations from the Forest Accelerated Succession Experiment in Michigan, USA. Ecosystems that experience high-severity disturbances that simplify ecosystem complexity can exhibit substantial declines in production during middle stages of succession. However, observations from these ecosystems have exerted a disproportionate in uence on assumptions regarding the trajectory and magnitude of age-related declines in forest production. We conclude that there is a wide ecological space for forests to maintain NPP and, in doing so, lessens the declines in NEP, with signi cant implications for the future of the North American carbon sink. Our intellectual frameworks for understanding forest C cycle dynamics and resilience need to catch up to our more complex and nuanced understanding of ecological succession.« less

Species richness effects on ecosystem multifunctionality depend on evenness, composition and spatial pattern

USGS Publications Warehouse

Maestre, F.T.; Castillo-Monroy, A. P.; Bowker, M.A.; Ochoa-Hueso, R.

2012-01-01

1. Recent studies have suggested that the simultaneous maintenance of multiple ecosystem functions (multifunctionality) is positively supported by species richness. However, little is known regarding the relative importance of other community attributes (e.g. spatial pattern, species evenness) as drivers of multifunctionality. 2. We conducted two microcosm experiments using model biological soil crust communities dominated by lichens to: (i) evaluate the joint effects and relative importance of changes in species composition, spatial pattern (clumped and random distribution of lichens), evenness (maximal and low evenness) and richness (from two to eight species) on soil functions related to nutrient cycling (β-glucosidase, urease and acid phosphatase enzymes, in situ N availability, total N, organic C, and N fixation), and (ii) assess how these community attributes affect multifunctionality. 3. Species richness, composition and spatial pattern affected multiple ecosystem functions (e.g. organic C, total N, N availability, β-glucosidase activity), albeit the magnitude and direction of their effects varied with the particular function, experiment and soil depth considered. Changes in species composition had effects on organic C, total N and the activity of β-glucosidase. Significant species richness × evenness and spatial pattern × evenness interactions were found when analysing functions such as organic C, total N and the activity of phosphatase. 4. The probability of sustaining multiple ecosystem functions increased with species richness, but this effect was largely modulated by attributes such as species evenness, composition and spatial pattern. Overall, we found that model communities with high species richness, random spatial pattern and low evenness increased multifunctionality. 5. Synthesis. Our results illustrate how different community attributes have a diverse impact on ecosystem functions related to nutrient cycling, and provide new experimental evidence illustrating the importance of the spatial pattern of organisms on ecosystem functioning. They also indicate that species richness is not the only biotic driver of multifunctionality, and that particular combinations of community attributes may be required to maximize it.

Top predators, mesopredators and their prey: interference ecosystems along bioclimatic productivity gradients.

PubMed

Elmhagen, B; Ludwig, G; Rushton, S P; Helle, P; Lindén, H

2010-07-01

1. The Mesopredator Release Hypothesis (MRH) suggests that top predator suppression of mesopredators is a key ecosystem function with cascading impacts on herbivore prey, but it remains to be shown that this top-down cascade impacts the large-scale structure of ecosystems. 2. The Exploitation Ecosystems Hypothesis (EEH) predicts that regional ecosystem structures are determined by top-down exploitation and bottom-up productivity. In contrast to MRH, EEH assumes that interference among predators has a negligible impact on the structure of ecosystems with three trophic levels. 3. We use the recolonization of a top predator in a three-level boreal ecosystem as a natural experiment to test if large-scale biomass distributions and population trends support MRH. Inspired by EEH, we also test if top-down interference and bottom-up productivity impact regional ecosystem structures. 4. We use data from the Finnish Wildlife Triangle Scheme which has monitored top predator (lynx, Lynx lynx), mesopredator (red fox, Vulpes vulpes) and prey (mountain hare, Lepus timidus) abundance for 17 years in a 200 000 km(2) study area which covers a distinct productivity gradient. 5. Fox biomass was lower than expected from productivity where lynx biomass was high, whilst hare biomass was lower than expected from productivity where fox biomass was high. Hence, where interference controlled fox abundance, lynx had an indirect positive impact on hare abundance as predicted by MRH. The rates of change indicated that lynx expansion gradually suppressed fox biomass. 6. Lynx status caused shifts between ecosystem structures. In the 'interference ecosystem', lynx and hare biomass increased with productivity whilst fox biomass did not. In the 'mesopredator release ecosystem', fox biomass increased with productivity but hare biomass did not. Thus, biomass controlled top-down did not respond to changes in productivity. This fulfils a critical prediction of EEH. 7. We conclude that the cascade involving top predators, mesopredators and their prey can determine large-scale biomass distribution patterns and regional ecosystem structures. Hence, interference within trophic levels has to be taken into account to understand how terrestrial ecosystem structures are shaped.

The experience of community residents in a fire-prone ecosystem: A case study on the San Bernardino National Forest

Treesearch

George T. Cvetkovich; Patricia L. Winter

2008-01-01

This report presents results from a study of San Bernardino National Forest community residents’ experiences with and perceptions of fire, fire management, and the Forest Service. Using self-administered surveys and focus group discussions, we found that participants had personal experiences with fire, were concerned about fire, and felt knowledgeable about effective...

Effects of Detrital Subsidies on Soft-Sediment Ecosystem Function Are Transient and Source-Dependent.

PubMed

Gladstone-Gallagher, Rebecca V; Lohrer, Andrew M; Lundquist, Carolyn J; Pilditch, Conrad A

2016-01-01

Detrital subsidies from marine macrophytes are prevalent in temperate estuaries, and their role in structuring benthic macrofaunal communities is well documented, but the resulting impact on ecosystem function is not understood. We conducted a field experiment to test the effects of detrital decay on soft-sediment primary production, community metabolism and nutrient regeneration (measures of ecosystem function). Twenty four (2 m2) plots were established on an intertidal sandflat, to which we added 0 or 220 g DW m-2 of detritus from either mangroves (Avicennia marina), seagrass (Zostera muelleri), or kelp (Ecklonia radiata) (n = 6 plots per treatment). Then, after 4, 17 and 46 d we measured ecosystem function, macrofaunal community structure and sediment properties. We hypothesized that (1) detrital decay would stimulate benthic primary production either by supplying nutrients to the benthic macrophytes, or by altering the macrofaunal community; and (2) ecosystem responses would depend on the stage and rate of macrophyte decay (a function of source). Avicennia detritus decayed the slowest with a half-life (t50) of 46 d, while Zostera and Ecklonia had t50 values of 28 and 2.6 d, respectively. However, ecosystem responses were not related to these differences. Instead, we found transient effects (up to 17 d) of Avicennia and Ecklonia detritus on benthic primary production, where initially (4 d) these detrital sources suppressed primary production, but after 17 d, primary production was stimulated in Avicennia plots relative to controls. Other ecosystem function response variables and the macrofaunal community composition were not altered by the addition of detritus, but did vary with time. By sampling ecosystem function temporally, we were able to capture the in situ transient effects of detrital subsidies on important benthic ecosystem functions.

The effects of food web structure on ecosystem function exceeds those of precipitation.

PubMed

Trzcinski, M Kurtis; Srivastava, Diane S; Corbara, Bruno; Dézerald, Olivier; Leroy, Céline; Carrias, Jean-François; Dejean, Alain; Céréghino, Régis

2016-09-01

Ecosystems are being stressed by climate change, but few studies have tested food web responses to changes in precipitation patterns and the consequences to ecosystem function. Fewer still have considered whether results from one geographic region can be applied to other regions, given the degree of community change over large biogeographic gradients. We assembled, in one field site, three types of macroinvertebrate communities within water-filled bromeliads. Two represented food webs containing both a fast filter feeder-microbial and slow detritivore energy channels found in Costa Rica and Puerto Rico, and one represented the structurally simpler food webs in French Guiana, which only contained the fast filter feeder-microbial channel. We manipulated the amount and distribution of rain entering bromeliads and examined how food web structure mediated ecosystem responses to changes in the quantity and temporal distribution of precipitation. Food web structure affected the survival of functional groups in general and ecosystem functions such as decomposition and the production of fine particulate organic matter. Ecosystem processes were more affected by decreased precipitation than were the abundance of micro-organisms and metazoans. In our experiments, the sensitivity of the ecosystem to precipitation change was primarily revealed in the food web dominated by the single filter feeder-microbial channel because other top-down and bottom-up processes were weak or absent. Our results show stronger effects of food web structure than precipitation change per se on the functioning of bromeliad ecosystems. Consequently, we predict that ecosystem function in bromeliads throughout the Americas will be more sensitive to changes in the distribution of species, rather than to the direct effects caused by changes in precipitation. © 2016 The Authors. Journal of Animal Ecology © 2016 British Ecological Society.

Ecosystem carbon storage does not vary with mean annual temperature in Hawaiian tropical montane wet forests.

PubMed

Selmants, Paul C; Litton, Creighton M; Giardina, Christian P; Asner, Gregory P

2014-09-01

Theory and experiment agree that climate warming will increase carbon fluxes between terrestrial ecosystems and the atmosphere. The effect of this increased exchange on terrestrial carbon storage is less predictable, with important implications for potential feedbacks to the climate system. We quantified how increased mean annual temperature (MAT) affects ecosystem carbon storage in above- and belowground live biomass and detritus across a well-constrained 5.2 °C MAT gradient in tropical montane wet forests on the Island of Hawaii. This gradient does not systematically vary in biotic or abiotic factors other than MAT (i.e. dominant vegetation, substrate type and age, soil water balance, and disturbance history), allowing us to isolate the impact of MAT on ecosystem carbon storage. Live biomass carbon did not vary predictably as a function of MAT, while detrital carbon declined by ~14 Mg of carbon ha(-1) for each 1 °C rise in temperature - a trend driven entirely by coarse woody debris and litter. The largest detrital pool, soil organic carbon, was the most stable with MAT and averaged 48% of total ecosystem carbon across the MAT gradient. Total ecosystem carbon did not vary significantly with MAT, and the distribution of ecosystem carbon between live biomass and detritus remained relatively constant across the MAT gradient at ~44% and ~56%, respectively. These findings suggest that in the absence of alterations to precipitation or disturbance regimes, the size and distribution of carbon pools in tropical montane wet forests will be less sensitive to rising MAT than predicted by ecosystem models. This article also provides needed detail on how individual carbon pools and ecosystem-level carbon storage will respond to future warming. © 2014 John Wiley & Sons Ltd.

Evaluating Energy Flows Through Jellyfish and Forage Fish and the Effects of Fishing on the Northern Humboldt Current Ecosystem

NASA Astrophysics Data System (ADS)

Chiaverano, L.; Robinson, K. L.; Ruzicka, J.; Quiñones, J.; Tam, J.; Acha, M.; Graham, W. M.; Brodeur, R.; Decker, M. B.; Hernandez, F., Jr.; Leaf, R.; Mianzan, H.; Uye, S. I.

2016-02-01

Increases in the frequency of jellyfish mass occurrences in a number of coastal areas around the globe have intensified concerns that some ecosystems are becoming "jellyfish-dominated". Gelatinous planktivores not only compete with forage fish for food, but also feed on fish eggs and larvae. When jellyfish abundance is high, the fraction of the energy and the efficiency at which it is transferred upwards in the food web are reduced compared with times when fish are dominant. Hence, ecosystems supporting major forage fish fisheries are the most likely to experience fish-to-jellyfish shifts due to the harvest pressure on mid-trophic planktivores. Although forage fish-jellyfish replacement cycles have been detected in recent decades in some productive, coastal ecosystems (e.g. Gulf of Mexico, Northern California Current), jellyfish are typically not included in ecosystem-based fisheries management (EBFM) production models. Here we explored the roles of jellyfish and forage fish as trophic energy transfer pathways to higher trophic levels in the Northern Humboldt Current (NHC) ecosystem, one of the most productive ecosystems in the world. A trophic network model with 33 functional groups was developed using ECOPATH and transformed to an end-to-end model using ECOTRAN techniques to map food web energy flows. Predicted, relative changes in functional group productivity were analyzed in simulations with varying forage fish consumption rates, jellyfish consumption rates, and forage fish harvest rates in a suite of static, alternative-energy-demand scenarios. Our modeling efforts will not only improve EBFM of forage fish and their predators in the NHC ecosystem, but also increase our understanding of trophic interactions between forage fish and large jellyfish, an important, but overlooked component in most ecosystem models to date.

The USDA Long-Term Agro-ecosystems Research (LTAR) Network

NASA Astrophysics Data System (ADS)

Goodrich, D. C.; Walthall, C. L.; Campbell, J. D.; Derner, J. D.; Huggins, D. R.; Kleinman, P. J. A.; Locke, M. A.; Sadler, J.; Steiner, J. L.; Strickland, T.; Swain, H.

2016-12-01

The USDA-Agricultural Research Service (ARS) has a multi-decadal to century long history of experimental watersheds, ranges and research farms throughout the USA. Many of these ARS research facilities, as well as three led by private foundations or land grant universities, are now part of the USDA Long-Term Agro-ecosystem Research (LTAR) network that currently has 18 locations. These 18 locations encompass a diversity of agricultural systems as well as provide a research platform for regional to national scale assessments and modeling scenarios of ecosystem goods and services for society. A central challenge that LTAR will address is: How can we sustain or enhance agricultural productivity, profitability, and ecosystem services to feed 9 billion people by 2050? Each LTAR location is designing a common experiment that consists of comparing "business as usual" to "aspirational agriculture" management strategies that reflect prevailing local to regional agricultural systems. The "aspirational agriculture" management strategy for each location will be forward-looking with innovative incorporations of cutting-edge technology, social-ecological systems involving human dimensions and economics, ecosystem services such as pollinator habitat and soil health, and paradigm shifting agricultural enterprise transformations. To accomplish the central challenge, LTAR locations will leverage existing historical data with new network-level initiatives such as wind erosion, phenology, water/carbon/nutrient/energy fluxes, complete water balances, greenhouse gas fluxes and remote sensing/modeling efforts to determine the sustainability of US agriculture across regional to continental scales. This presentation will provide an overview of the current status of the LTAR network, describe several common experiments, showcase the data management systems and web presentations of this data, as well as recent network findings.

Near Real-time Ecological Forecasting of Peatland Responses to Warming and CO2 Treatment through EcoPAD-SPRUCE

NASA Astrophysics Data System (ADS)

Huang, Y.; Jiang, J.; Stacy, M.; Ricciuto, D. M.; Hanson, P. J.; Sundi, N.; Luo, Y.

2016-12-01

Ecological forecasting is critical in various aspects of our coupled human-nature systems, such as disaster risk reduction, natural resource management and climate change mitigation. Novel advancements are in urgent need to deepen our understandings of ecosystem dynamics, boost the predictive capacity of ecology, and provide timely and effective information for decision-makers in a rapidly changing world. Our Ecological Platform for Assimilation of Data (EcoPAD) facilitates the integration of current best knowledge from models, manipulative experimentations, observations and other modern techniques and provides both near real-time and long-term forecasting of ecosystem dynamics. As a case study, the web-based EcoPAD platform synchronizes real- or near real-time field measurements from the Spruce and Peatland Responses Under Climatic and Environmental Change Experiment (SPRUCE), a whole ecosystem warming and CO2 enrichment treatment experiment, assimilates multiple data streams into process based models, enhances timely feedback between modelers and experimenters, and ultimately improves ecosystem forecasting and makes best utilization of current knowledge. In addition to enable users to (i) estimate model parameters or state variables, (ii) quantify uncertainty of estimated parameters and projected states of ecosystems, (iii) evaluate model structures, (iv) assess sampling strategies, and (v) conduct ecological forecasting, EcoPAD-SPRUCE automated the workflow from real-time data acquisition, model simulation to result visualization. EcoPAD-SPRUCE promotes seamless feedback between modelers and experimenters, hand in hand to make better forecasting of future changes. The framework of EcoPAD-SPRUCE (with flexible API, Application Programming Interface) is easily portable and will benefit scientific communities, policy makers as well as the general public.

Introduction to a special section on ecohydrology of semiarid environments: Confronting mathematical models with ecosystem complexity

NASA Astrophysics Data System (ADS)

Svoray, Tal; Assouline, Shmuel; Katul, Gabriel

2015-11-01

Current literature provides large number of publications about ecohydrological processes and their effect on the biota in drylands. Given the limited laboratory and field experiments in such systems, many of these publications are based on mathematical models of varying complexity. The underlying implicit assumption is that the data set used to evaluate these models covers the parameter space of conditions that characterize drylands and that the models represent the actual processes with acceptable certainty. However, a question raised is to what extent these mathematical models are valid when confronted with observed ecosystem complexity? This Introduction reviews the 16 papers that comprise the Special Section on Eco-hydrology of Semiarid Environments: Confronting Mathematical Models with Ecosystem Complexity. The subjects studied in these papers include rainfall regime, infiltration and preferential flow, evaporation and evapotranspiration, annual net primary production, dispersal and invasion, and vegetation greening. The findings in the papers published in this Special Section show that innovative mathematical modeling approaches can represent actual field measurements. Hence, there are strong grounds for suggesting that mathematical models can contribute to greater understanding of ecosystem complexity through characterization of space-time dynamics of biomass and water storage as well as their multiscale interactions. However, the generality of the models and their low-dimensional representation of many processes may also be a "curse" that results in failures when particulars of an ecosystem are required. It is envisaged that the search for a unifying "general" model, while seductive, may remain elusive in the foreseeable future. It is for this reason that improving the merger between experiments and models of various degrees of complexity continues to shape the future research agenda.

Who Benefits from Ecosystem Services? A Case Study for Central Kalimantan, Indonesia

NASA Astrophysics Data System (ADS)

Suwarno, Aritta; Hein, Lars; Sumarga, Elham

2016-02-01

There is increasing experience with the valuation of ecosystem services. However, to date, less attention has been devoted to who is actually benefiting from ecosystem services. This nevertheless is a key issue, in particular, if ecosystem services analysis and valuation is used to support environmental management. This study assesses and analyzes how the monetary benefits of seven ecosystem services are generated in Central Kalimantan Province, Indonesia, are distributed to different types of beneficiaries. We analyze the following ecosystem services: (1) timber production; (2) rattan collection; (3) jelutong resin collection; (4) rubber production (based on permanent agroforestry systems); (5) oil palm production on three management scales (company, plasma farmer, and independent smallholder); (6) paddy production; and (7) carbon sequestration. Our study shows that the benefits generated from these services differ markedly between the stakeholders, which we grouped into private, public, and household entities. The distribution of these benefits is strongly influenced by government policies and in particular benefit sharing mechanisms. Hence, land-use change and policies influencing land-use change can be expected to have different impacts on different stakeholders. Our study also shows that the benefits generated by oil palm conversion, a main driver for land-use change in the province, are almost exclusively accrued by companies and at this point in time are shared unequally with local stakeholders.

An ecosystem services framework to support both practical conservation and economic development.

PubMed

Tallis, Heather; Kareiva, Peter; Marvier, Michelle; Chang, Amy

2008-07-15

The core idea of the Millennium Ecosystem Assessment is that the human condition is tightly linked to environmental condition. This assertion suggests that conservation and development projects should be able to achieve both ecological and social progress without detracting from their primary objectives. Whereas "win-win" projects that achieve both conservation and economic gains are a commendable goal, they are not easy to attain. An analysis of World Bank projects with objectives of alleviating poverty and protecting biodiversity revealed that only 16% made major progress on both objectives. Here, we provide a framework for anticipating win-win, lose-lose, and win-lose outcomes as a result of how people manage their ecosystem services. This framework emerges from detailed explorations of several case studies in which biodiversity conservation and economic development coincide and cases in which there is joint failure. We emphasize that scientific advances around ecosystem service production functions, tradeoffs among multiple ecosystem services, and the design of appropriate monitoring programs are necessary for the implementation of conservation and development projects that will successfully advance both environmental and social goals. The potentially bright future of jointly advancing ecosystem services, conservation, and human well-being will be jeopardized unless a global monitoring effort is launched that uses the many ongoing projects as a grand experiment.

An ecosystem services framework to support both practical conservation and economic development

PubMed Central

Tallis, Heather; Kareiva, Peter; Marvier, Michelle; Chang, Amy

2008-01-01

The core idea of the Millennium Ecosystem Assessment is that the human condition is tightly linked to environmental condition. This assertion suggests that conservation and development projects should be able to achieve both ecological and social progress without detracting from their primary objectives. Whereas “win–win” projects that achieve both conservation and economic gains are a commendable goal, they are not easy to attain. An analysis of World Bank projects with objectives of alleviating poverty and protecting biodiversity revealed that only 16% made major progress on both objectives. Here, we provide a framework for anticipating win–win, lose–lose, and win–lose outcomes as a result of how people manage their ecosystem services. This framework emerges from detailed explorations of several case studies in which biodiversity conservation and economic development coincide and cases in which there is joint failure. We emphasize that scientific advances around ecosystem service production functions, tradeoffs among multiple ecosystem services, and the design of appropriate monitoring programs are necessary for the implementation of conservation and development projects that will successfully advance both environmental and social goals. The potentially bright future of jointly advancing ecosystem services, conservation, and human well-being will be jeopardized unless a global monitoring effort is launched that uses the many ongoing projects as a grand experiment. PMID:18621702

Impacts of insect disturbance on the structure, composition, and functioning of oak-pine forests

NASA Astrophysics Data System (ADS)

Medvigy, D.; Schafer, K. V.; Clark, K. L.

2011-12-01

Episodic disturbance is an essential feature of terrestrial ecosystems, and strongly modulates their structure, composition, and functioning. However, dynamic global vegetation models that are commonly used to make ecosystem and terrestrial carbon budget predictions rarely have an explicit representation of disturbance. One reason why disturbance is seldom included is that disturbance tends to operate on spatial scales that are much smaller than typical model resolutions. In response to this problem, the Ecosystem Demography model 2 (ED2) was developed as a way of tracking the fine-scale heterogeneity arising from disturbances. In this study, we used ED2 to simulate an oak-pine forest that experiences episodic defoliation by gypsy moth (Lymantria dispar L). The model was carefully calibrated against site-level data, and then used to simulate changes in ecosystem composition, structure, and functioning on century time scales. Compared to simulations that include gypsy moth defoliation, we show that simulations that ignore defoliation events lead to much larger ecosystem carbon stores and a larger fraction of deciduous trees relative to evergreen trees. Furthermore, we find that it is essential to preserve the fine-scale nature of the disturbance. Attempts to "smooth out" the defoliation event over an entire grid cells led to large biases in ecosystem structure and functioning.

Water and nitrogen availability co-control ecosystem CO2 exchange in a semiarid temperate steppe.

PubMed

Zhang, Xiaolin; Tan, Yulian; Li, Ang; Ren, Tingting; Chen, Shiping; Wang, Lixin; Huang, Jianhui

2015-10-23

Both water and nitrogen (N) availability have significant effects on ecosystem CO2 exchange (ECE), which includes net ecosystem productivity (NEP), ecosystem respiration (ER) and gross ecosystem photosynthesis (GEP). How water and N availability influence ECE in arid and semiarid grasslands is still uncertain. A manipulative experiment with additions of rainfall, snow and N was conducted to test their effects on ECE in a semiarid temperate steppe of northern China for three consecutive years with contrasting natural precipitation. ECE increased with annual precipitation but approached peak values at different precipitation amount. Water addition, especially summer water addition, had significantly positive effects on ECE in years when the natural precipitation was normal or below normal, but showed trivial effect on GEP when the natural precipitation was above normal as effects on ER and NEP offset one another. Nitrogen addition exerted non-significant or negative effects on ECE when precipitation was low but switched to a positive effect when precipitation was high, indicating N effect triggered by water availability. Our results indicate that both water and N availability control ECE and the effects of future precipitation changes and increasing N deposition will depend on how they can change collaboratively in this semiarid steppe ecosystem.

Ecosystem heterogeneity determines the ecological resilience of the Amazon to climate change.

PubMed

Levine, Naomi M; Zhang, Ke; Longo, Marcos; Baccini, Alessandro; Phillips, Oliver L; Lewis, Simon L; Alvarez-Dávila, Esteban; Segalin de Andrade, Ana Cristina; Brienen, Roel J W; Erwin, Terry L; Feldpausch, Ted R; Monteagudo Mendoza, Abel Lorenzo; Nuñez Vargas, Percy; Prieto, Adriana; Silva-Espejo, Javier Eduardo; Malhi, Yadvinder; Moorcroft, Paul R

2016-01-19

Amazon forests, which store ∼ 50% of tropical forest carbon and play a vital role in global water, energy, and carbon cycling, are predicted to experience both longer and more intense dry seasons by the end of the 21st century. However, the climate sensitivity of this ecosystem remains uncertain: several studies have predicted large-scale die-back of the Amazon, whereas several more recent studies predict that the biome will remain largely intact. Combining remote-sensing and ground-based observations with a size- and age-structured terrestrial ecosystem model, we explore the sensitivity and ecological resilience of these forests to changes in climate. We demonstrate that water stress operating at the scale of individual plants, combined with spatial variation in soil texture, explains observed patterns of variation in ecosystem biomass, composition, and dynamics across the region, and strongly influences the ecosystem's resilience to changes in dry season length. Specifically, our analysis suggests that in contrast to existing predictions of either stability or catastrophic biomass loss, the Amazon forest's response to a drying regional climate is likely to be an immediate, graded, heterogeneous transition from high-biomass moist forests to transitional dry forests and woody savannah-like states. Fire, logging, and other anthropogenic disturbances may, however, exacerbate these climate change-induced ecosystem transitions.

Who Benefits from Ecosystem Services? A Case Study for Central Kalimantan, Indonesia.

PubMed

Suwarno, Aritta; Hein, Lars; Sumarga, Elham

2016-02-01

There is increasing experience with the valuation of ecosystem services. However, to date, less attention has been devoted to who is actually benefiting from ecosystem services. This nevertheless is a key issue, in particular, if ecosystem services analysis and valuation is used to support environmental management. This study assesses and analyzes how the monetary benefits of seven ecosystem services are generated in Central Kalimantan Province, Indonesia, are distributed to different types of beneficiaries. We analyze the following ecosystem services: (1) timber production; (2) rattan collection; (3) jelutong resin collection; (4) rubber production (based on permanent agroforestry systems); (5) oil palm production on three management scales (company, plasma farmer, and independent smallholder); (6) paddy production; and (7) carbon sequestration. Our study shows that the benefits generated from these services differ markedly between the stakeholders, which we grouped into private, public, and household entities. The distribution of these benefits is strongly influenced by government policies and in particular benefit sharing mechanisms. Hence, land-use change and policies influencing land-use change can be expected to have different impacts on different stakeholders. Our study also shows that the benefits generated by oil palm conversion, a main driver for land-use change in the province, are almost exclusively accrued by companies and at this point in time are shared unequally with local stakeholders.

LAI is the major cause of divergence in CO2 fertilization effect in land surface models

NASA Astrophysics Data System (ADS)

Li, Q.; Luo, Y.; Lu, X.; Wang, Y.; Huang, X.; Lin, G., Sr.

2017-12-01

Concentration-carbon feedback (β), also called CO2 fertilization effect, is an important feedback between terrestrial ecosystems and atmosphere to alleviate global climate change. However, models participating in C4MIP and CMIP5 predicted diverse CO2 fertilization effects under future CO2 inceasing scenarios. Hence identifing the key processes dominating the divergence of β in land surface models is of significance. We calculated CO2 fertilization effects from leaf level, canopy gross productivity level, net ecosystem productivity level and ecosystem carbon stock level in Community Atmosphere Biosphere Land Exchange (CABLE) model. Our results identified LAI is the key factor dominating the divergence of β among C3 plants in CABLE model. Saturation of the ecosystem productivity to increasing CO2 is not only regulated by leaf-level response, but also the response of LAI to increasing CO2. The greatest variation among C3 plants at ecosystem level suggests that other processes such as different allocation patterns and soil carbon dynamics of various vegetation types are also responsible for the divergence. Our results indicate that processes regarding to LAI need to be better calibrated according to experiments and observations in order to better represent the response of ecosystem productivity to increasing CO2.

A meeting of the waters: interdisciplinary challenges and opportunities in tidal rivers

USGS Publications Warehouse

Ensign, Scott H.; Noe, Gregory B.; Hupp, Cliff R.; Fagherazzi, Sergio

2012-01-01

At the interface of estuarine tides and freshwater rivers lie wetland and aquatic ecosystems, which experience dramatic effects of sea level rise. There, nontidal channels and riparian floodplains are transforming into tidal ecosystems, and tidal freshwater ecosystems are receiving increasing salinity. These river-floodplain systems have both fluvial characteristics, including meandering channels and expansive floodplain forests, and estuarine characteristics, including tides and intertidal wetlands [see Barendregt et al., 2009; Conner et al., 2007, and references therein]. Because tidal rivers lie at the disciplinary divide between fluvial and estuarine science, a knowledge gap has developed in scientists' understanding of the geomorphic and biogeochemical response of these environments to sea level rise, climate change, and anthropogenically driven variations in watershed exports.

Coupling of the spatial dynamic of picoplankton and nanoflagellate grazing pressure and carbon flow of the microbial food web in the subtropical pelagic continental shelf ecosystem

NASA Astrophysics Data System (ADS)

Chiang, K.-P.; Tsai, A.-Y.; Tsai, P.-J.; Gong, G.-C.; Tsai, S.-F.

2013-01-01

In order to investigate the mechanism of spatial dynamics of picoplankton community (bacteria and Synechococcus spp.) and estimate the carbon flux of the microbial food web in the oligotrophic Taiwan Warm Current Water of subtropical marine pelagic ecosystem, we conducted size-fractionation experiments in five cruises by the R/V Ocean Research II during the summers of 2010 and 2011 in the southern East China Sea. We carried out culture experiments using surface water which, according to a temperature-salinity (T-S) diagram, is characterized as oligotrophic Taiwan Current Warm Water. We found a negative correlation bettween bacteria growth rate and temperature, indicating that the active growth of heterotrophic bacteria might be induced by nutrients lifted from deep layer by cold upwelling water. This finding suggests that the area we studied was a bottom-up control pelagic ecosystem. We suggest that the microbial food web of an oligotrophic ecosystem may be changed from top-down control to resource supply (bottom-up control) when a physical force brings nutrient into the oligotrophic ecosystem. Upwelling brings nutrient-rich water to euphotic zone and promotes bacteria growth, increasing the picoplankton biomass which increased the consumption rate of nanoflagellate. The net growth rate (growth rate-grazing rate) becomes negative when the densities of bacteria and Synechococcus spp. are lower than the threshold values. The interaction between growth and grazing will limit the abundances of bacteria (105-106 cells mL-1 and Synechococcus spp. (104-105 cells mL-1) within a narrow range, forming a predator-prey eddy. Meanwhile, 62% of bacteria production and 55% of Synechococcus spp. production are transported to higher trophic level (nanoflagellate), though the cascade effect might cause an underestimation of both percentages of transported carbon. Based on the increasing number of sizes we found in the size-fractionation experiments, we estimated that the predation values were underestimated by 28.3% for bacteria and 34.6% for Synechococcus spp. Taking these corrections into consideration, we conclude that picoplankton production is balanced by nonoflagellate grazing and the diet of nanoflagellate is composed of 64% bacteria and 36% Synechococcus spp.

Chemical Results of Laboratory Dry/Rewet Experiments Conducted on Wetland Soils from Two Sites in the Everglades, Florida

USGS Publications Warehouse

Orem, William H.

2008-01-01

Drought and fire are natural environmental factors that have historically impacted and shaped the Everglades ecosystem. For example, drought and fire help to maintain the existing ecosystem biotic assemblage by periodically eradicating invading flora not adapted to living with this normal aspect of Everglades' ecology. Flora native to the Everglades are adapted to withstand normal drought cycles and all but the most intense fire conditions that burn into the peat substrate. Remobilization of nutrients and other elements from wetland soil following drought/fire and rewetting may actually stimulate plant re-growth, assisting in the recovery of the ecosystem from these events, and play a role in maintaining the geochemical balance of the ecosystem. Although drought/fire cycles occur naturally in the Everglades' ecosystem, the frequency, intensity, and duration of these events have been altered by anthropogenic activities. The hydrology of the ecosystem has been changed by the construction of water management structures starting around 1900 and continuing through the 1970s. These structures include canals, levees, and pumping stations around Lake Okeechobee and within the Everglades. In addition, water management practices have preferentially moved water toward agricultural and urban areas and away from the Everglades during periods of low rainfall. One result of these practices has been more severe drought and fire cycles within the ecosystem compared to pre-development activity. A major goal of restoration efforts in the Everglades is to restore a more natural flow of water into the ecosystem to alleviate some of the extreme drought and fire conditions witnessed during the past several decades.

Seven years (2008-2014) of meteorological observations plus a synthetic El Nino drought for BCI Panama.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Powell, Thomas; Kueppers, Lara; Paton, Steve

This dataset is a derivative product of raw meteorological data collected at Barro Colorado Island, Panama (see acknowledgements below). This dataset contains the following: 1) a seven-year record (2008-2014) of meteorological observations from BCI that is in a comma delimited text format, 2) an R-script that converts the observed meteorology into an hdf5 format that can be read by the ED2 model, 3) two decades of meteorological drivers in hdf5 format that are based on the 7-year record of observations and include a synthetic 2-yr El Nino drought, 4) a ReadMe.txt file that explains how the data in the hdf5more » meteorological drivers correspond to the observations. The raw meteorological data were further QC'd as part of the NGEE-Tropics project to derive item 1 above. The R-script makes the appropriate unit conversions for all observed meteorological variables to be compatible with the ED2 model. The R-script also converts RH into specific humidity, splits total shortwave radiation into its 4-stream parts, and calculates longwave radiation from air temperature and RH. The synthetic El Nino drought is based on selected months from the observed meteorology where in each, precipitation (only) of the selected months was modified to reflect the precipitation patterns of the 1982/83 El Nino observed at BCI.« less

Rodent-Mediated Interactions Among Seed Species of Differing Quality in a Shrubsteppe Ecosystem

USGS Publications Warehouse

Beard, Karen H.; Faulhaber, Craig A.; Howe, Frank P.; Edwards, Thomas C.

2013-01-01

Interactions among seeds, mediated by granivorous rodents, are likely to play a strong role in shrubsteppe ecosystem restoration. Past studies typically consider only pairwise interactions between preferred and less preferred seed species, whereas rangeland seedings are likely to contain more than 2 seed species, potentially leading to complex interactions. We examined how the relative proportion of seeds in a 3-species polyculture changes rodent seed selectivity (i.e., removal) and indirect interactions among seeds. We presented 2 rodent species, Peromyscus maniculatus (deer mice) and Perognathus parvus (pocket mice), in arenas with 3-species seed mixtures that varied in the proportion of a highly preferred, moderately preferred, and least preferred seed species, based on preferences determined in this study. We then conducted a field experiment in a pocket mouse—dominated ecosystem with the same 3-species seed mixtures in both “treated” (reduced shrub and increased forb cover) and “untreated” shrubsteppe. In the arena experiment, we found that rodents removed more of the highly preferred seed when the proportions of all 3 seeds were equal. Moderately preferred seeds experienced increased removal when the least preferred seed was in highest proportion. Removal of the least preferred seed increased when the highly preferred seed was in highest proportion. In the field experiment, results were similar to those from the arena experiment and did not differ between treated and untreated shrubsteppe areas. Though our results suggest that 3-species mixtures induce complex interactions among seeds, managers applying these results to restoration efforts should carefully consider the rodent community present and the potential fate of removed seeds.

Experimental Biodiversity Enrichment in Oil-Palm-Dominated Landscapes in Indonesia

PubMed Central

Teuscher, Miriam; Gérard, Anne; Brose, Ulrich; Buchori, Damayanti; Clough, Yann; Ehbrecht, Martin; Hölscher, Dirk; Irawan, Bambang; Sundawati, Leti; Wollni, Meike; Kreft, Holger

2016-01-01

Tropical biodiversity is threatened by the expansion of oil-palm plantations. Reduced-impact farming systems such as agroforests, have been proposed to increase biodiversity and ecosystem functioning. In regions where oil-palm plantations already dominate the landscape, this increase can only be achieved through systematic ecological restoration. However, our knowledge about the underlying ecological and socio-economic processes, constraints, and trade-offs of ecological restoration in oil-palm landscapes is very limited. To bridge this gap, we established a long-term biodiversity enrichment experiment. We established experimental tree islands in a conventional oil-palm plantation and systematically varied plot size, tree diversity, and tree species composition. Here, we describe the rationale and the design of the experiment, the ecosystem variables (soil, topography, canopy openness) and biotic characteristics (associated vegetation, invertebrates, birds) of the experimental site prior to the establishment of the experiment, and initial experimental effects on the fauna. Already one year after establishment of the experiment, tree plantings had an overall positive effect on the bird and invertebrate communities at the plantation scale. The diversity and abundance of invertebrates was positively affected by the size of the tree islands. Based on these results, we expect a further increase of biodiversity and associated ecological functions in the future. The long-term interdisciplinary monitoring of ecosystem variables, flora, fauna, and socio-economic aspects will allow us to evaluate the suitability of tree islands as a restoration measure. Thereof, guidelines for ecologically improved and socio-economically viable restoration and management concepts could be developed. PMID:27799935

Collaborative implementation for ecological restoration on US public lands: implications for legal context, accountability, and adaptive management

Treesearch

William H. Butler; Ashley Monroe; Sarah McCaffrey

2015-01-01

The Collaborative Forest Landscape Restoration Program (CFLRP), established in 2009, encourages collaborative landscape scale ecosystem restoration efforts on United States Forest Service (USFS) lands. Although the USFS employees have experience engaging in collaborative planning, CFLRP requires collaboration in implementation, a domain where little prior experience...

Design and performance of B4WarmED, an aboveground and belowground free-air warming experiment at the temperate-boreal forest ecotone

USDA-ARS?s Scientific Manuscript database

Conducting manipulative climate change experiments in forests is challenging, given their spatial heterogeneity and canopy complexity. One specific challenge involves warming both plants and soils to depth in ecosystems without much bare ground. We describe the design, implementation, and performanc...

Field testing existence values for riparian ecosystems

Treesearch

John W. Duffield; Chris J. Neher; David A. Patterson; Patricia A. Champ

2007-01-01

This paper presents preliminary findings on a cash and contingent valuation (cv) experiment. The study replicates major elements of an earlier (1990) experiment, which solicited hypothetical and actual donations to benefit instream flows for Montana fisheries. Extensions of the earlier work include: repeat contacts to increase response rate, follow-up of the contingent...

Silviculture: From the Cradle of Forestry to Ecosystem Management

Treesearch

Louise H. Foley

1994-01-01

The National Silviculture Workshop, hosted by the National Forests in North Carolina, the Southern Region (Region 8), and the Southeastern Forest Experiment Station, was held November 1993 at the Kanuga Conference Center, Hendersonville , NC. The purpose of this workshop was to review , discuss, and share silvicultural research inform ation and management experience...

Contribution of trees and grasses to ecosystem fluxes of water, carbon, and energy throughout the seasons under different nutrient availability

NASA Astrophysics Data System (ADS)

El-Madany, T. S.; Migliavacca, M.; Perez-Priego, O.; Luo, Y.; Moreno, G.; Carrara, A.; Kolle, O.; Reichstein, M.

2017-12-01

In semi-arid savanna type ecosystems, the carbon and water cycle are closely related to each other. Water availability is the main driver for the development and phenology of the vegetation, especially for annual plants. Depending on tree density, nutrient availability and species the contribution of the tree- and the herbaceous layer to ecosystem fluxes can vary substantially. We present data from an ecosystem scale nutrient manipulation experiment within a Mediterranean savanna type ecosystem which is used for cattle. The footprint areas of two out of three ecosystem eddy co-variance (EC) towers were fertilized with nitrogen (NT) and nitrogen plus phosphorous (NPT) while the third one served as the control tower (CT). At each ecosystem EC-tower an additional herbaceous layer tower was installed that only sampled fluxes from the herbaceous layer. Under certain assumptions flux differences between the ecosystem EC and the herbaceous layer EC systems can be considered as the contribution of the trees to the ecosystem fluxes. Based on phenology of the herbaceous layer estimated through green-chromatic-coordinates from digital imagery the year was separated into spring, senescence, regreening, and winter. The focus of the analysis is (i) the evaluation of the method and how it works throughout the different seasons and (ii) the quantification of the contribution of trees and grasses to ecosystem fluxes of water, carbon, and energy under different environmental conditions and nutrient stoichiometry. The contribution of the trees to total ecosystem fluxes is variable in time. Especially, during the beginning of the senescence period high evapotranspiration rates and largest carbon uptake are measured while the contribution to sensible heat fluxes is largest during the end of the summer. During the regreening and winter the contribution of ET is relatively constant around 0.25 mm d-1. During the peak of the greenness ET and carbon flux of the herbaceous EC tower are sometimes higher than fluxes measured by the ecosystem tower which is most likely caused by the mismatch in footprints. Whenever the herbaceous layer is active it contributes clearly more to the fluxes as compared to the trees.

Light-stress avoidance mechanisms in a Sphagnum-dominated wet coastal Arctic tundra ecosystem in Alaska.

PubMed

Zona, D; Oechel, Walter C; Richards, James H; Hastings, Steven; Kopetz, Irene; Ikawa, Hiroki; Oberbauer, Steven

2011-03-01

The Arctic experiences a high-radiation environment in the summer with 24-hour daylight for more than two months. Damage to plants and ecosystem metabolism can be muted by overcast conditions common in much of the Arctic. However, with climate change, extreme dry years and clearer skies could lead to the risk of increased photoxidation and photoinhibition in Arctic primary producers. Mosses, which often exceed the NPP of vascular plants in Arctic areas, are often understudied. As a result, the effect of specific environmental factors, including light, on these growth forms is poorly understood. Here, we investigated net ecosystem exchange (NEE) at the ecosystem scale, net Sphagnum CO2 exchange (NSE), and photoinhibition to better understand the impact of light on carbon exchange from a moss-dominated coastal tundra ecosystem during the summer season 2006. Sphagnum photosynthesis showed photoinhibition early in the season coupled with low ecosystem NEE. However, later in the season, Sphagnum maintained a significant CO2 uptake, probably for the development of subsurface moss layers protected from strong radiation. We suggest that the compact canopy structure of Sphagnum reduces light penetration to the subsurface layers of the moss mat and thereby protects the active photosynthetic tissues from damage. This stress avoidance mechanism allowed Sphagnum to constitute a significant percentage (up to 60%) of the ecosystem net daytime CO2 uptake at the end of the growing season despite the high levels of radiation experienced.

Effects of warming and clipping on ecosystem carbon fluxes across two hydrologically contrasting years in an alpine meadow of the Qinghai-Tibet Plateau.

PubMed

Peng, Fei; You, Quangang; Xu, Manhou; Guo, Jian; Wang, Tao; Xue, Xian

2014-01-01

Responses of ecosystem carbon (C) fluxes to human disturbance and climatic warming will affect terrestrial ecosystem C storage and feedback to climate change. We conducted a manipulative experiment to investigate the effects of warming and clipping on soil respiration (Rs), ecosystem respiration (ER), net ecosystem exchange (NEE) and gross ecosystem production (GEP) in an alpine meadow in a permafrost region during two hydrologically contrasting years (2012, with 29.9% higher precipitation than the long-term mean, and 2013, with 18.9% lower precipitation than the long-tem mean). Our results showed that GEP was higher than ER, leading to a net C sink (measured by NEE) over the two growing seasons. Warming significantly stimulated ecosystem C fluxes in 2012 but did not significantly affect these fluxes in 2013. On average, the warming-induced increase in GEP (1.49 µ mol m(-2) s(-1)) was higher than in ER (0.80 µ mol m(-2) s(-1)), resulting in an increase in NEE (0.70 µ mol m(-2) s(-1)). Clipping and its interaction with warming had no significant effects on C fluxes, whereas clipping significantly reduced aboveground biomass (AGB) by 51.5 g m(-2) in 2013. These results suggest the response of C fluxes to warming and clipping depends on hydrological variations. In the wet year, the warming treatment caused a reduction in water, but increases in soil temperature and AGB contributed to the positive response of ecosystem C fluxes to warming. In the dry year, the reduction in soil moisture, caused by warming, and the reduction in AGB, caused by clipping, were compensated by higher soil temperatures in warmed plots. Our findings highlight the importance of changes in soil moisture in mediating the responses of ecosystem C fluxes to climate warming in an alpine meadow ecosystem.

Effects of Warming and Clipping on Ecosystem Carbon Fluxes across Two Hydrologically Contrasting Years in an Alpine Meadow of the Qinghai-Tibet Plateau

PubMed Central

Peng, Fei; You, Quangang; Xu, Manhou; Guo, Jian; Wang, Tao; Xue, Xian

2014-01-01

Responses of ecosystem carbon (C) fluxes to human disturbance and climatic warming will affect terrestrial ecosystem C storage and feedback to climate change. We conducted a manipulative experiment to investigate the effects of warming and clipping on soil respiration (Rs), ecosystem respiration (ER), net ecosystem exchange (NEE) and gross ecosystem production (GEP) in an alpine meadow in a permafrost region during two hydrologically contrasting years (2012, with 29.9% higher precipitation than the long-term mean, and 2013, with 18.9% lower precipitation than the long-tem mean). Our results showed that GEP was higher than ER, leading to a net C sink (measured by NEE) over the two growing seasons. Warming significantly stimulated ecosystem C fluxes in 2012 but did not significantly affect these fluxes in 2013. On average, the warming-induced increase in GEP (1.49 µ mol m−2s−1) was higher than in ER (0.80 µ mol m−2s−1), resulting in an increase in NEE (0.70 µ mol m−2s−1). Clipping and its interaction with warming had no significant effects on C fluxes, whereas clipping significantly reduced aboveground biomass (AGB) by 51.5 g m−2 in 2013. These results suggest the response of C fluxes to warming and clipping depends on hydrological variations. In the wet year, the warming treatment caused a reduction in water, but increases in soil temperature and AGB contributed to the positive response of ecosystem C fluxes to warming. In the dry year, the reduction in soil moisture, caused by warming, and the reduction in AGB, caused by clipping, were compensated by higher soil temperatures in warmed plots. Our findings highlight the importance of changes in soil moisture in mediating the responses of ecosystem C fluxes to climate warming in an alpine meadow ecosystem. PMID:25291187

Architecture of collapse: regime shift and recovery in an hierarchically structured marine ecosystem.

PubMed

Daskalov, Georgi M; Boicenco, Laura; Grishin, Alexandre N; Lazar, Luminita; Mihneva, Vesselina; Shlyakhov, Vladislav A; Zengin, Mustafa

2017-04-01

By the late 20th century, a series of events or 'natural experiments', for example the depletion of apex predators, extreme eutrophication and blooms of invasive species, had suggested that the Black Sea could be considered as a large ecosystem 'laboratory'. The events resulted in regime shifts cascading through all trophic levels, disturbing ecosystem functioning and damaging the water environment. Causal pathways by which the external (hydroclimate, overfishing) and internal (food web interactions) drivers provoke regime shifts are investigated. Statistical data analyses supported by an interpretative framework based on hierarchical ecosystem theory revealed mechanisms of hierarchical incorporation of environmental factors into the ecosystem. Evidence links Atlantic teleconnections to Black Sea hydroclimate, which together with fishing shapes variability in fish stocks. The hydroclimatic signal is conveyed through the food web via changes in productivity at all levels, to planktivorous fish. Fluctuating fish abundance is believed to induce a lagged change in competitor jelly plankton that cascades down to phytoplankton and influences water quality. Deprived of the stabilising role of apex predators, the Black Sea's hierarchical ecosystem organisation is susceptible to both environmental and anthropogenic stresses, and increased fishing makes fish stock collapses highly probable. When declining stocks are confronted with burgeoning fishing effort associated with the inability of fishery managers and decision-makers to adapt rapidly to changes in fish abundance, there is overfishing and stock collapse. Management procedures are ineffective at handling complex phenomena such as ecosystem regime shifts because of the shortage of suitable explanatory models. The proposed concepts and models reported here relate the hydroclimate, overfishing and invasive species to shifts in ecosystem functioning and water quality, unravelling issues such as the causality of ecosystem interactions and mechanisms and offering potential for finding ways to reverse regime shifts. We advocate a management approach aiming at restoring ecosystem hierarchy that might mitigate the costly consequences of regime shifts. © 2016 John Wiley & Sons Ltd.

Using the CARDAMOM framework to retrieve global terrestrial ecosystem functioning properties

NASA Astrophysics Data System (ADS)

Exbrayat, Jean-François; Bloom, A. Anthony; Smallman, T. Luke; van der Velde, Ivar R.; Feng, Liang; Williams, Mathew

2016-04-01

Terrestrial ecosystems act as a sink for anthropogenic emissions of fossil-fuel and thereby partially offset the ongoing global warming. However, recent model benchmarking and intercomparison studies have highlighted the non-trivial uncertainties that exist in our understanding of key ecosystem properties like plant carbon allocation and residence times. It leads to worrisome differences in terrestrial carbon stocks simulated by Earth system models, and their evolution in a warming future. In this presentation we attempt to provide global insights on these properties by merging an ecosystem model with remotely-sensed global observations of leaf area and biomass through a data-assimilation system: the CARbon Data MOdel fraMework (CARDAMOM). CARDAMOM relies on a Markov Chain Monte Carlo algorithm to retrieve confidence intervals of model parameters that regulate ecosystem properties independently of any prior land-cover information. The MCMC method thereby enables an explicit representation of the uncertainty in land-atmosphere fluxes and the evolution of terrestrial carbon stocks through time. Global experiments are performed for the first decade of the 21st century using a 1°×1° spatial resolution. Relationships emerge globally between key ecosystem properties. For example, our analyses indicate that leaf lifespan and leaf mass per area are highly correlated. Furthermore, there exists a latitudinal gradient in allocation patterns: high latitude ecosystems allocate more carbon to photosynthetic carbon (leaves) while plants invest more carbon in their structural parts (wood and root) in the wet tropics. Overall, the spatial distribution of these ecosystem properties does not correspond to usual land-cover maps and are also partially correlated with disturbance regimes. For example, fire-prone ecosystems present statistically significant higher values of carbon use efficiency than less disturbed ecosystems experiencing similar climatic conditions. These results raise concerns on the suitability of the plant functional type paradigm for terrestrial carbon cycling.

Predicting ecosystem shifts requires new approaches that integrate the effects of climate change across entire systems

PubMed Central

Russell, Bayden D.; Harley, Christopher D. G.; Wernberg, Thomas; Mieszkowska, Nova; Widdicombe, Stephen; Hall-Spencer, Jason M.; Connell, Sean D.

2012-01-01

Most studies that forecast the ecological consequences of climate change target a single species and a single life stage. Depending on climatic impacts on other life stages and on interacting species, however, the results from simple experiments may not translate into accurate predictions of future ecological change. Research needs to move beyond simple experimental studies and environmental envelope projections for single species towards identifying where ecosystem change is likely to occur and the drivers for this change. For this to happen, we advocate research directions that (i) identify the critical species within the target ecosystem, and the life stage(s) most susceptible to changing conditions and (ii) the key interactions between these species and components of their broader ecosystem. A combined approach using macroecology, experimentally derived data and modelling that incorporates energy budgets in life cycle models may identify critical abiotic conditions that disproportionately alter important ecological processes under forecasted climates. PMID:21900317

Ecosystem services: From theory to implementation

PubMed Central

Daily, Gretchen C.; Matson, Pamela A.

2008-01-01

Around the world, leaders are increasingly recognizing ecosystems as natural capital assets that supply life-support services of tremendous value. The challenge is to turn this recognition into incentives and institutions that will guide wise investments in natural capital, on a large scale. Advances are required on three key fronts, each featured here: the science of ecosystem production functions and service mapping; the design of appropriate finance, policy, and governance systems; and the art of implementing these in diverse biophysical and social contexts. Scientific understanding of ecosystem production functions is improving rapidly but remains a limiting factor in incorporating natural capital into decisions, via systems of national accounting and other mechanisms. Novel institutional structures are being established for a broad array of services and places, creating a need and opportunity for systematic assessment of their scope and limitations. Finally, it is clear that formal sharing of experience, and defining of priorities for future work, could greatly accelerate the rate of innovation and uptake of new approaches. PMID:18621697