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1

The Distributed Hydrology Soil Vegetation Model  

Microsoft Academic Search

The use of distributed physically based models in environmental analysis is becoming more common as greater demands are placed on hydrologic models, particularly for problems involving prediction of future hydrologic conditions resulting from changes in land use or climate. The Distributed Hydrology Soil Vegetation Model (DHSVM) is a physically based model that provides a dynamic representation of the spatial distribution

Mark S. Wigmosta; Bart Nijssen; Pascal Storck; VP Singh; DK Frevert

2002-01-01

2

Importance of Soil Texture in Paleo-Vegetation Modeling Studies  

Microsoft Academic Search

The utility of a dynamic global vegetation model (DGVM) depends on the accuracy of the background climatology driving the model and the boundary conditions. In this study, we examine the sensitivity of the NCAR LSM-DGVM to one aspect of the boundary condition, the global soil texture. Soil texture is a critical factor influencing the availability of soil moisture. Available soil

C. J. Shellito; S. Clifthorne; L. C. Sloan; L. Kueppers

2005-01-01

3

A nonlinear coupled soil moisture-vegetation model  

NASA Astrophysics Data System (ADS)

Based on the physical analysis that the soil moisture and vegetation depend mainly on the precipitation and evaporation as well as the growth, decay and consumption of vegetation a nonlinear dynamic coupled system of soil moisture-vegetation is established. Using this model, the stabilities of the steady states of vegetation are analyzed. This paper focuses on the research of the vegetation catastrophe point which represents the transition between aridness and wetness to a great extent. It is shown that the catastrophe point of steady states of vegetation depends mainly on the rainfall P and saturation value v0, which is selected to balance the growth and decay of vegetation. In addition, when the consumption of vegetation remains constant, the analytic solution of the vegetation equation is obtained.

Liu, Shikuo; Liu, Shida; Fu, Zuntao; Sun, Lan

2005-06-01

4

Modeling radium and radon transport through soil and vegetation  

USGS Publications Warehouse

A one-dimensional flow and transport model was developed to describe the movement of two fluid phases, gas and water, within a porous medium and the transport of 226Ra and 222Rn within and between these two phases. Included in this model is the vegetative uptake of water and aqueous 226Ra and 222Rn that can be extracted from the soil via the transpiration stream. The mathematical model is formulated through a set of phase balance equations and a set of species balance equations. Mass exchange, sink terms and the dependence of physical properties upon phase composition couple the two sets of equations. Numerical solution of each set, with iteration between the sets, is carried out leading to a set-iterative compositional model. The Petrov-Galerkin finite element approach is used to allow for upstream weighting if required for a given simulation. Mass lumping improves solution convergence and stability behavior. The resulting numerical model was applied to four problems and was found to produce accurate, mass conservative solutions when compared to published experimental and numerical results and theoretical column experiments. Preliminary results suggest that the model can be used as an investigative tool to determine the feasibility of phytoremediating radium and radon-contaminated soil. ?? 2003 Elsevier Science B.V. All rights reserved.

Kozak, J. A.; Reeves, H. W.; Lewis, B. A.

2003-01-01

5

A design of two simple models to predict PCDD/F concentrations in vegetation and soils.  

PubMed

The vegetation and soil levels of the 17 polychlorinated dibenzo-p-dioxin and dibenzofuran (PCDD/F) toxic congeners were calculated by means of a vegetation and a soil model, respectively. Both models predicted the levels of the 17 PCDD/F congeners in quite good agreement with the observed results although the soil model was more accurate than the vegetation model. Four different pathways of contribution to the vegetation concentrations were taken into account: vapour-phase absorption, dry particle deposition, wet particle deposition and uptake by root. The most important pathway was the vapour-phase absorption and the less was the uptake by root. In the soils model four pathways were considered: background soil concentration, dry particle deposition, wet particle deposition and uptake by root. After the background concentration, the most important pathway was the wet deposition. PMID:12002466

Meneses, Montserrat; Schuhmacher, Marta; Domingo, Jose L

2002-03-01

6

Measuring and modelling water related soil-vegetation feedbacks in a fallow plot  

NASA Astrophysics Data System (ADS)

Land fallowing is one possible response to shortage of water for irrigation. Leaving the soil unseeded implies a change of the soil functioning that has an impact on the water cycle. The development of a soil crust in the open spaces between the patterns of grass weed affects the soil properties and the field scale water balance. The objectives of this study are to test the potential of integrated non invasive geophysical methods and ground-image analysis and to quantify the effect of the soil vegetation interaction on the water balance of a fallow land at the local and plot scale. We measured repeatedly in space and time local soil saturation and vegetation cover over two small plots located in southern Sardinia, Italy, during a controlled irrigation experiment. One plot was left unseeded and the other was cultivated. The comparative analysis of ERT maps of soil moisture evidenced a considerably different hydrologic response to irrigation of the two plots. Local measurements of soil saturation and vegetation cover were repeated in space to evidence a positive feedback between weed growth and infiltration at the fallow plot. A simple bucket model captured the different soil moisture dynamics at the two plots during the infiltration experiment and was used to estimate the impact of the soil vegetation feedback on the yearly water balance at the fallow site.

Ursino, N.; Cassiani, G.; Deiana, R.; Vignoli, G.; Boaga, J.

2013-08-01

7

Parameterization of bucket models for soil-vegetation-atmosphere modeling under seasonal climatic regimes  

NASA Astrophysics Data System (ADS)

We investigate the potential impact of accounting for seasonal variations in the climatic forcing and using different methods to parameterize the soil water content at field capacity on the water balance components computed by a bucket model (BM). The single-layer BM of Guswa et al. (2002) is employed, whereas the Richards equation (RE) based Soil Water Atmosphere Plant (SWAP) model is used as a benchmark model. The results are analyzed for two differently-textured soils and for some synthetic runs under real-like seasonal weather conditions, using 100 time-series of stochastically-generated daily rainfall data. Since transient soil-moisture dynamics and climatic seasonality play a key role in certain zones of the World, such as in Mediterranean land areas, a specific feature of this study is to test the prediction capability of the bucket model under a condition where seasonal variations in rainfall are not in phase with the variations in plant transpiration and. Reference is made to a hydrologic year in which we have a rainy period (starting 1 November and lasting 151 days) where vegetation is basically assumed in a dormant stage, followed by a drier and rainless period with a vegetation regrowth phase. Better agreement between BM and RE-SWAP intercomparison results are obtained when BM is parameterized by a field capacity value determined through the drainage method proposed by Romano and Santini (2002). Depending on the vegetation regrowth or dormant seasons, rainfall variability within a season results in transpiration regimes and soil moisture fluctuations with distinctive features. During the vegetation regrowth season, transpiration exerts a key control on soil water budget with respect to rainfall. During the dormant season of vegetation, the precipitation regime becomes an important climate forcing. Simulations also highlight the occurrence of bimodality in the probability distribution of soil moisture during the season when plants are dormant, reflecting that soil, it being of coarser or finer texture, can be preferentially in either wetter or drier states over this period.

Romano, N.; Palladino, M.; Chirico, G. B.

2011-05-01

8

Parameterization of a bucket model for soil-vegetation-atmosphere modeling under seasonal climatic regimes  

NASA Astrophysics Data System (ADS)

We investigate the potential impact of accounting for seasonal variations in the climatic forcing and using different methods to parameterize the soil water content at field capacity on the water balance components computed by a bucket model (BM). The single-layer BM of Guswa et al. (2002) is employed, whereas the Richards equation (RE) based Soil Water Atmosphere Plant (SWAP) model is used as a benchmark model. The results are analyzed for two differently-textured soils and for some synthetic runs under real-like seasonal weather conditions, using stochastically-generated daily rainfall data for a period of 100 years. Since transient soil-moisture dynamics and climatic seasonality play a key role in certain zones of the World, such as in Mediterranean land areas, a specific feature of this study is to test the prediction capability of the bucket model under a condition where seasonal variations in rainfall are not in phase with the variations in plant transpiration. Reference is made to a hydrologic year in which we have a rainy period (starting 1 November and lasting 151 days) where vegetation is basically assumed in a dormant stage, followed by a drier and rainless period with a vegetation regrowth phase. Better agreement between BM and RE-SWAP intercomparison results are obtained when BM is parameterized by a field capacity value determined through the drainage method proposed by Romano and Santini (2002). Depending on the vegetation regrowth or dormant seasons, rainfall variability within a season results in transpiration regimes and soil moisture fluctuations with distinctive features. During the vegetation regrowth season, transpiration exerts a key control on soil water budget with respect to rainfall. During the dormant season of vegetation, the precipitation regime becomes an important climate forcing. Simulations also highlight the occurrence of bimodality in the probability distribution of soil moisture during the season when plants are dormant, reflecting that soil, it being of coarser or finer texture, can be preferentially in either wetter or drier states over this period.

Romano, N.; Palladino, M.; Chirico, G. B.

2011-12-01

9

An integrated model of soil, hydrology, and vegetation for carbon dynamics in wetland ecosystems  

Microsoft Academic Search

Wetland ecosystems are an important component in global carbon (C) cycles and may exert a large influence on global climate change. Predictions of C dynamics require us to consider interactions among many critical factors of soil, hydrology, and vegetation. However, few such integrated C models exist for wetland ecosystems. In this paper, we report a simulation model, Wetland-DNDC, for C

Yu Zhang; Changsheng Li; Carl C. Trettin; Harbin Li; Ge Sun

2002-01-01

10

A Coupled Energy and Water Balance Model for Snow-Vegetation-Soil Systems  

NASA Astrophysics Data System (ADS)

In mountainous and cold regions of the world snowmelt dominates the water balance, yet is quantified poorly despite the wealth of available remote sensing observations. Field measurements of snow cover and soil moisture are limited to experimental sites while the accuracy of soil moisture measurements from passive and active microwave sensors such as the upcoming SMOS and SMAP missions depends on a good physical understanding of the soil system. An improved approach to interpret remote sensing observations is to use a physically - based model in conjunction with the observations. However, many of the models currently available are either too complex for use across a range of scales, or lack elements that govern the energy and mass balance of the system (for example, snow, soil or vegetation). A new coupled energy and water balance model that integrates snow and soil moisture has been developed to simulate the evolution of the snow cover in addition to soil temperature and moisture profiles. The model was formed by coupling Snobal, a physically - based two-layer snow model, with a simplified version of SHAW, a multi-layer soil heat and water balance model that also simulates soil freezing. We present a point test of the model for a snow covered bare soil using hourly measurements of meteorological conditions, from an experimental site within the Reynolds Creek Experimental Watershed in Idaho, USA. These data were used to drive the model, which was then evaluated against hourly measured snow deposition and melt, as well as soil temperature and moisture profiles from the same site. Later research will focus on the vegetation component of the coupled system. The coupled model is computationally simple enough for regional simulations and could be used to form the basis of a data assimilation framework to retrieve snow and soil parameters from remote sensing measurements.

Marks, D.; Sandells, M.; Flerchinger, G.

2009-05-01

11

Prediction of Mass Wasting, Erosion, and Sediment Transport With the Distributed Hydrology-Soil-Vegetation Model  

Microsoft Academic Search

Erosion and sediment transport in a temperate forested watershed are predicted with a new sediment module linked to the Distributed Hydrology-Soil-Vegetation Model (DHSVM). The DHSVM sediment module represents the main sources of sediment generation in forested environments: mass wasting, hillslope erosion and road surface erosion. It produces failures based on a factor-of-safety analysis with the infinite slope model through use

C. O. Doten; J. S. Lanini; L. C. Bowling; D. P. Lettenmaier

2004-01-01

12

Reflectance of Vegetation, Soil, and Water.  

National Technical Information Service (NTIS)

The author has identified the following significant results. The Kubelka-Munk model, a regression model, and a combination of these models were used to extract plant, soil, and shadow reflectance components of vegetated surfaces. The combination model was...

C. L. Wiegand

1974-01-01

13

Two models to compute an adjusted Green Vegetation Fraction taking into account the spatial variability of soil NDVI  

Microsoft Academic Search

The green vegetation fraction (Fg) is an important climate and hydrologic model parameter. The commonly- used Fg model is a simple linear mixing of two NDVI end-members: bare soil NDVI (NDVIo) and full vegetation NDVI (NDVI?). NDVI? is generally set as a percentile of the historical maximum NDVI for each land cover. This approach works well for areas where Fg

L. M. Montandon; E. Small

2008-01-01

14

Modeling temporal and large-scale spatial variability of soil respiration from soil water availability, temperature and vegetation productivity indices  

NASA Astrophysics Data System (ADS)

Field-chamber measurements of soil respiration from 17 different forest and shrubland sites in Europe and North America were summarized and analyzed with the goal to develop a model describing seasonal, interannual and spatial variability of soil respiration as affected by water availability, temperature, and site properties. The analysis was performed at a daily and at a monthly time step. With the daily time step, the relative soil water content in the upper soil layer expressed as a fraction of field capacity was a good predictor of soil respiration at all sites. Among the site variables tested, those related to site productivity (e.g., leaf area index) correlated significantly with soil respiration, while carbon pool variables like standing biomass or the litter and soil carbon stocks did not show a clear relationship with soil respiration. Furthermore, it was evidenced that the effect of precipitation on soil respiration stretched beyond its direct effect via soil moisture. A general statistical nonlinear regression model was developed to describe soil respiration as dependent on soil temperature, soil water content, and site-specific maximum leaf area index. The model explained nearly two thirds of the temporal and intersite variability of soil respiration with a mean absolute error of 0.82 ?mol m-2 s-1. The parameterized model exhibits the following principal properties: (1) At a relative amount of upper-layer soil water of 16% of field capacity, half-maximal soil respiration rates are reached. (2) The apparent temperature sensitivity of soil respiration measured as Q10 varies between 1 and 5 depending on soil temperature and water content. (3) Soil respiration under reference moisture and temperature conditions is linearly related to maximum site leaf area index. At a monthly timescale, we employed the approach by [2002] that used monthly precipitation and air temperature to globally predict soil respiration (T&P model). While this model was able to explain some of the month-to-month variability of soil respiration, it failed to capture the intersite variability, regardless of whether the original or a new optimized model parameterization was used. In both cases, the residuals were strongly related to maximum site leaf area index. Thus, for a monthly timescale, we developed a simple T&P&LAI model that includes leaf area index as an additional predictor of soil respiration. This extended but still simple model performed nearly as well as the more detailed time step model and explained 50% of the overall and 65% of the site-to-site variability. Consequently, better estimates of globally distributed soil respiration should be obtained with the new model driven by satellite estimates of leaf area index. Before application at the continental or global scale, this approach should be further tested in boreal, cold-temperate, and tropical biomes as well as for non-woody vegetation.

Reichstein, Markus; Rey, Ana; Freibauer, Annette; Tenhunen, John; Valentini, Riccardo; Banza, Joao; Casals, Pere; Cheng, Yufu; Grünzweig, Jose M.; Irvine, James; Joffre, Richard; Law, Beverly E.; Loustau, Denis; Miglietta, Franco; Oechel, Walter; Ourcival, Jean-Marc; Pereira, Joao S.; Peressotti, Alessandro; Ponti, Francesca; Qi, Ye; Rambal, Serge; Rayment, Mark; Romanya, Joan; Rossi, Federica; Tedeschi, Vanessa; Tirone, Giampiero; Xu, Ming; Yakir, Dan

2003-12-01

15

Modeling carbon dynamics in vegetation and soil under the impact of soil erosion and deposition  

USGS Publications Warehouse

Soil erosion and deposition may play important roles in balancing the global atmospheric carbon budget through their impacts on the net exchange of carbon between terrestrial ecosystem and the atmosphere. Few models and studies have been designed to assess these impacts. In this study, we developed a general ecosystem model, Erosion-Deposition-Carbon-Model (EDCM), to dynamically simulate the influences of rainfall-induced soil erosion and deposition on soil organic carbon (SOC) dynamics in soil profiles. EDCM was applied to several landscape positions in the Nelson Farm watershed in Mississippi, including ridge top (without erosion or deposition), eroding hillslopes, and depositional sites that had been converted from native forests to croplands in 1870. Erosion reduced the SOC storage at the eroding sites and deposition increased the SOC storage at the depositional areas compared with the site without erosion or deposition. Results indicated that soils were consistently carbon sources to the atmosphere at all landscape positions from 1870 to 1950, with lowest source strength at the eroding sites (13 to 24 gC m-2 yr-1), intermediate at the ridge top (34 gC m-2 yr-1), and highest at the depositional sites (42 to 49 gC m-2 yr-1). During this period, erosion reduced carbon emissions via dynamically replacing surface soil with subsurface soil that had lower SOC contents (quantity change) and higher passive SOC fractions (quality change). Soils at all landscape positions became carbon sinks from 1950 to 1997 due to changes in management practices (e.g., intensification of fertilization and crop genetic improvement). The sink strengths were highest at the eroding sites (42 to 44 gC m-2 yr-1 , intermediate at the ridge top (35 gC m-2 yr-1), and lowest at the depositional sites (26 to 29 gC m-2 yr-1). During this period, erosion enhanced carbon uptake at the eroding sites by continuously taking away a fraction of SOC that can be replenished with enhanced plant residue input. Overall, soil erosion and deposition reduced CO2 emissions from the soil into the atmosphere by exposing low carbon-bearing soil at eroding sites and by burying SOC at depositional sites. The results suggest that failing to account for the impact of soil erosion and deposition may potentially contribute to an overestimation of both the total historical carbon released from soils owing to land use change and the contemporary carbon sequestration rates at the eroding sites.

Liu, S.; Bliss, N.; Sundquist, E.; Huntington, T. G.

2003-01-01

16

Using Distributed-Hydrology-Soil-Vegetation Model to Study Road Effects on Stream flow and Soil Moisture  

NASA Astrophysics Data System (ADS)

The distributed-hydrology-soil-vegetation model (DHSVM) was applied in Pang Khum Experimental Watershed (PKEW), located near 19.05\\deg N, 98.65\\deg E in the mountainous region of northern Thailand, headwaters of the Chao Phraya River system. PKEW has a highly seasonal rainfall regime, with 90% of the annual 1200-1400 mm rainfall occurring during the southwest summer monsoon. The elevation of PKEW ranges from approximately 1100 to 1500 m. Total road area including road banks is about 1.2% of the basin area. About 57% of the road area occurs on slopes steeper than 10%. All roads are unpaved. Land cover in PKEW is affected by swidden agriculture. Six land cover and nine soil classes are identified in the basin. We have been working in the area since 1997 as part of the Thailand Roads Project (TRP). Within the basin, we are monitoring microclimate at two sites, soil moisture at four sites, and rainfall at five sites. Streamflow is measured at the outlet. Based on digital elevation data, DHSVM explicitly accounts for the spatial distribution of the stream and road networks, soil depth, soil and vegetation types. The model run period, including warm up, calibration and validation, is from August 1997 to January 2001. Field measurements provide forcing data, calibration data, and guidance in parameter selection. Model calibration and validation were done by aggregating simulated hourly soil moisture and stream flow into daily values and comparing them with aggregated daily measurements. For the calibration period, RMSEs of soil moisture and streamflow were lower than the observed variability as represented by the standard deviation, median absolute deviation, and (for stream flow) interquartile range. Model performance drops in validation period, but RMSEs remain near or lower than observed variability. We ran DHSVM with and without roads to examine their effects. Significant effects of roads were found despite the very low proportion of the watershed covered by roads and road banks. Streamflow for road and non-road cases was significantly different (p < 0.0001) based on the Wilcoxon signed rank test. In general, roads increase peak volume for short, intense storms, but reduced whole-period discharge by about 5.5%. Soil moisture was affected in cells where roads occur. In cells where water exited the road onto the hillslope, soil moisture was higher than it was without the road. In cells with roads, but without water flowing onto the hillslope, soil moisture was higher in some cases and lower in others.

Cuo, L.; Giambelluca, T. W.; Ziegler, A. D.; Nullet, M. A.

2003-12-01

17

Sensitivity of Groundwater Recharge to Variations of Climate, Soils, and Vegetation Based on Unsaturated-Flow Modeling  

Microsoft Academic Search

Understanding the relative importance of climate, vegetation, and soils in controlling groundwater recharge is important for estimating effects of climate variability and land use\\/land cover change on recharge\\/water resources. The purpose of this study was to evaluate the sensitivity of groundwater recharge to variations in climate, soil type, and vegetation type using unsaturated-flow modeling and to further assess the sensitivity

K. E. Keese; B. R. Scanlon; R. C. Reedy

2004-01-01

18

Validation and comparison of two soil-vegetation-atmosphere transfer models for tropical Africa  

NASA Astrophysics Data System (ADS)

This study aims to compare and validate two soil-vegetation-atmosphere-transfer (SVAT) schemes: TERRA-ML and the Community Land Model (CLM). Both SVAT schemes are run in standalone mode (decoupled from an atmospheric model) and forced with meteorological in-situ measurements obtained at several tropical African sites. Model performance is quantified by comparing simulated sensible and latent heat fluxes with eddy-covariance measurements. Our analysis indicates that the Community Land Model corresponds more closely to the micrometeorological observations, reflecting the advantages of the higher model complexity and physical realism. Deficiencies in TERRA-ML are addressed and its performance is improved: (1) adjusting input data (root depth) to region-specific values (tropical evergreen forest) resolves dry-season underestimation of evapotranspiration; (2) adjusting the leaf area index and albedo (depending on hard-coded model constants) resolves overestimations of both latent and sensible heat fluxes; and (3) an unrealistic flux partitioning caused by overestimated superficial water contents is reduced by adjusting the hydraulic conductivity parameterization. CLM is by default more versatile in its global application on different vegetation types and climates. On the other hand, with its lower degree of complexity, TERRA-ML is much less computationally demanding, which leads to faster calculation times in a coupled climate simulation.

Akkermans, T.; Lauwaet, D.; Demuzere, M.; Vogel, G.; Nouvellon, Y.; Ardö, J.; Caquet, B.; de Grandcourt, A.; Merbold, L.; Kutsch, W.; van Lipzig, N.

2012-06-01

19

Development of a fully-distributed daily hydrologic feedback model addressing vegetation, land cover, and soil water dynamics (VELAS)  

NASA Astrophysics Data System (ADS)

Quantifying the impacts of vegetation-land cover on hydrologic feedbacks.Fully coupled water dynamics through the soil zone.Integration of VELAS modeling with GIS database.Flexibility of the VELAS model for different scale of time and space.

Park, Changhui; Lee, Jejung; Koo, Min-Ho

2013-06-01

20

A Soil Thermal Conductivity Model Based upon Component Conductivities and Fractions for use in Soil-Vegetation-Atmosphere Transfer Models  

NASA Astrophysics Data System (ADS)

A soil Thermal Conductivity (TC) model is proposed based upon De Vries' soil thermal conductivity theory, but with fewer degrees of freedom. The model is designed for water contents between the soil wilting point and soil saturation - a relevant range for many applications. The TC model uses component thermal conductivities and a component-dependent assignment of shape factors to obtain thermal conductivity estimates whose only degrees of freedom are fractions of sand, clay, and liquid water. TC model predictions show good agreement with thermal conductivity measurements. Performances of our Land Surface Process (LSP) model during 30-day dry down simulations were negligibly affected by substitution of the TC model for the original De Vries model.

Gu, H.; Lin, T.; Judge, J.; England, A. W.

2005-12-01

21

Vegetation and soil respiration: Correlations and controls  

Microsoft Academic Search

Soil respiration rates vary significantly among major plant biomes, suggesting that vegetation type influences the rate of soil respiration. However, correlations among climatic factors, vegetation distributions, and soil respiration rates make cause-effect arguments diffi- cult. Vegetation may affect soil respiration by influencing soil microclimate and structure, the quantity of detritus supplied to the soil, the quality of that detritus, and

JAMES W. RAICH; AYDIN TUFEKCIOGLU

2000-01-01

22

Bibliography: salt impacts on vegetation and soils  

SciTech Connect

This report is a bibliography of literature addressing the impacts of salt on vegetation and soils. The titles in this listing were seleccted from several computerized literature searches with the intent of identifying resources which may be used to assess the effects of salt deposition around a repository. There is a host of literature, but most of the studies are specific to the mechanism introducing the salt to the soil. This bibliography is organized around these mechanisms. The specific topics on salt impacts include studies on the Permian Basin; Chalk Point, MD, cooling tower; other cooling towers; modeling; highway deicing; and soil-water-vegetation systems.

Not Available

1984-08-01

23

Evaluation of Snow Depth and Soil Temperatures Predicted by the Hydro Thermodynamic Soil Vegetation Scheme Coupled with the Fifth-Generation Pennsylvania State University NCAR Mesoscale Model  

Microsoft Academic Search

The Hydro Thermodynamic Soil Vegetation Scheme (HTSVS) coupled in a two-way mode with the fifth-generation Pennsylvania State University National Center for Atmospheric Research (NCAR) Mesoscale Meteorological Model (MM5) is evaluated for a typical snowmelt episode in the Baltic region by means of observations at 25 soil temperature, 355 snow-depth, and 344 precipitation sites that have, in total, 1000, 1775, and

Balachandrudu Narapusetty; Nicole Mölders

2005-01-01

24

Anthropogenic soil erosion over the Holocene: Application of a new dynamic soils module for global vegetation models  

NASA Astrophysics Data System (ADS)

Over the course of the Holocene, anthropogenic activities have transformed the surface of the Earth. In no way has human impact been more important or longer lasting than the transformation of soils, where erosion and sediment transport over the past 10,000 years have led to irreversible changes in landscapes. Soil erosion also affected global carbon and nutrient cycles, and could have amplified or attenuated ongoing changes in the Earth's climate. To quantify the role of anthropogenically induced soil development and erosion in the Earth system, we developed a new module of global soil dynamics: soil formation, erosion, and sediment transport, that is suitable for global application at 0.5° resolution. We incorporated this soil module into the LPJ-DGVM and performed a series of simulations to quantify the spatial and temporal pattern of global soil change over the Holocene. The soil formation module models bedrock-to-soil conversion rates as exponentially decreasing with soil depth. Parameters for soil formation in different geological units were extracted from a review of existing literature. Our global soil erosion formulation is based on the Revised Universal Soil Loss Equation (RUSLE), but importantly accounts for sediment deposition and the net export of sediment out of a relatively large and geomorphologically heterogeneous gridcell. Our new module was developed by running the detailed soil erosion-deposition model WaTEM/SEDEM at 3 arc-second resolution to derive generalized topographical scaling relations that accurately represent hillslope length, slope gradient and sediment delivery ratio. We show that, at large spatial scale, sediment delivery ratio and the area affected by sediment deposition can be easily estimated from topographical parameters such as mean LS factor and wetness index. We include the feedback between soil formation and soil erosion by adjusting the soil erosion rates for soil depth and stoniness. The results of our Holocene-long simulations indicate that millennia of human impact, mainly deforestation and cultivation, led to exhaustion of soil resources in many parts of the world. In particular, the eastern and southern Mediterranean, the northern Andes, and southern China were strongly affected by anthropogenic soil erosion. Some areas experienced declining rates of soil loss already in the early first millennium CE because of total removal of the soil column. Cumulative carbon emissions to the atmosphere over the Holocene as a result of anthropogenic soil erosion could have approached 200 Pg. Remote sensing-based global maps of topography, soils, and bedrock geology that have recently become available are a valuable resource that will improve our ability to model soil dynamics for the past and future.

Kaplan, J. O.; Vanwalleghem, T.

2012-04-01

25

A soil-vegetation-atmosphere transfer scheme for modeling spatially variable water and energy balance processes  

Microsoft Academic Search

In support of the eventual goal to integrate remotely sensed observations with coupled )and-atmosphere mode)s, a soil-vegetation-atmosphere transfer scheme is presented which can represent spatial)y variable water and energy balance processes on timesca)es of minutes to months. This scheme differs from previous schemes developed to address similar objectives in that it: (1) represents horizontal heterogeneity and transport in a TOPMODEL

C. D. Peters-Lidard; M. S. Zion; E. F. Wood

1997-01-01

26

Mediterranean Analogs of California Soil Vegetation Types.  

National Technical Information Service (NTIS)

Analogies have been established between Soil-Vegetation types in Italy and Greece to those in California on the basis of field observations. Consistent changes in soil and vegetation properties were observed as sequences with elevation change on typical r...

P. J. Zinke

1965-01-01

27

Comparison of four models to determine surface soil moisture from C-band radar imagery in a sparsely vegetated semiarid landscape  

Microsoft Academic Search

Four approaches for deriving estimates of near-surface soil moisture from radar imagery in a semiarid, sparsely vegetated rangeland were evaluated against in situ measurements of soil moisture. The approaches were based on empirical, physical, semiempirical, and image difference techniques. The empirical approach involved simple linear regression of radar backscatter on soil moisture, while the integral equation method (IEM) model was

D. P. Thoma; M. S. Moran; R. Bryant; M. Rahman; C. D. Holifield-Collins; S. Skirvin; E. E. Sano; K. Slocum

2006-01-01

28

Modelling temporal and large-scale spatial variability of soil respiration from soil water availability, temperature and vegetation productivity indices  

NASA Astrophysics Data System (ADS)

Field-chamber measurements of soil respiration from 17 different forest and shrubland sites in Europe and North America were summarized and analyzed with the goal to develop a model describing seasonal, inter-annual and spatial variability of soil respiration as affected by water availability, temperature and site properties. The analysis was performed at a daily and at a monthly time step. With the daily time step, the relative soil water content in the upper soil layer expressed as a fraction of field capacity was a good predictor of soil respiration at all sites. Among the site variables tested, those related to site productivity (e.g. leaf area index) correlated significantly with soil respiration, while carbon pool variables like standing biomass or the litter and soil carbon stocks did not show a clear relationship with soil respiration. Furthermore, it was evidenced that the effect of precipitation on soil respiration stretched beyond its direct effect via soil moisture. A general statistical non-linear regression model was developed to describe soil respiration as dependent on soil temperature, soil water content and site-specific maximum leaf area index. The model explained nearly two thirds of the temporal and inter-site variability of soil respiration with a mean absolute error of 0.82 µmol m-2 s-1. The parameterised model exhibits the following principal properties: 1) At a relative amount of upper-layer soil water of 16% of field capacity half-maximal soil respiration rates are reached. 2) The apparent temperature sensitivity of soil respiration measured as Q10 varies between 1 and 5 depending on soil temperature and water content. 3) Soil respiration under reference moisture and temperature conditions is linearly related to maximum site leaf area index. At a monthly time-scale we employed the approach by Raich et al. (2002, Global Change Biol. 8, 800-812) that used monthly precipitation and air temperature to globally predict soil respiration (T&P-model). While this model was able to explain some of the month-to-month variability of soil respiration, it failed to capture the inter-site variability, regardless whether the original or a new optimized model parameterization was used. In both cases, the residuals were strongly related to maximum site leaf area index. Thus, for a monthly time scale we developed a simple T&P&LAI-model that includes leaf area index as an additional predictor of soil respiration. This extended but still simple model performed nearly as well as the more detailed time-step model and explained 50 % of the overall and 65% of the site-to-site variability. Consequently, better estimates of globally distributed soil respiration should be obtained with the new model driven by satellite estimates of leaf area index.

Reichstein, M.; Rey, A.; Freibauer, A.; Tenhunen, J.; Valentini, R.; Soil Respiration Synthesis Team

2003-04-01

29

Multi-year assessment of soil-vegetation-atmosphere transfer (SVAT) modeling uncertainties over a Mediterranean agricultural site  

NASA Astrophysics Data System (ADS)

Vegetation productivity and water balance of Mediterranean regions will be particularly affected by climate and land-use changes. In order to analyze and predict these changes through land surface models, a critical step is to quantify the uncertainties associated with these models (processes, parameters) and their implementation over a long period of time. Besides, uncertainties attached to the data used to force these models (atmospheric forcing, vegetation and soil characteristics, crop management practices...) which are generally available at coarse spatial resolution (>1-10 km) and for a limited number of plant functional types, need to be evaluated. This paper aims at assessing the uncertainties in water (evapotranspiration) and energy fluxes estimated from a Soil Vegetation Atmosphere Transfer (SVAT) model over a Mediterranean agricultural site. While similar past studies focused on particular crop types and limited period of time, the originality of this paper consists in implementing the SVAT model and assessing its uncertainties over a long period of time (10 years), encompassing several cycles of distinct crops (wheat, sorghum, sunflower, peas). The impacts on the SVAT simulations of the following sources of uncertainties are characterized: - Uncertainties in atmospheric forcing are assessed comparing simulations forced with local meteorological measurements and simulations forced with re-analysis atmospheric dataset (SAFRAN database). - Uncertainties in key surface characteristics (soil, vegetation, crop management practises) are tested comparing simulations feeded with standard values from global database (e.g. ECOCLIMAP) and simulations based on in situ or site-calibrated values. - Uncertainties dues to the implementation of the SVAT model over a long period of time are analyzed with regards to crop rotation. The SVAT model being analyzed in this paper is ISBA in its a-gs version which simulates the photosynthesis and its coupling with the stomata conductance, as well as the time course of the plant biomass and the Leaf Area Index (LAI). The experiment was conducted at the INRA-Avignon (France) crop site (ICOS associated site), for which 10 years of energy and water eddy fluxes, soil moisture profiles, vegetation measurements, agricultural practises are available for distinct crop types. The uncertainties in evapotranspiration and energy flux estimates are quantified from both 10-year trend analysis and selected daily cycles spanning a range of atmospheric conditions and phenological stages. While the net radiation flux is correctly simulated, the cumulated latent heat flux is under-estimated. Daily plots indicate i) an overestimation of evapotranspiration over bare soil probably due to an overestimation of the soil water reservoir available for evaporation and ii) an under-estimation of transpiration for developed canopy. Uncertainties attached to the re-analysis atmospheric data show little influence on the cumulated values of evapotranspiration. Better performances are reached using in situ soil depths and site-calibrated photosynthesis parameters compared to the simulations based on the ECOCLIMAP standard values. Finally, this paper highlights the impact of the temporal succession of vegetation cover and bare soil on the simulation of soil moisture and evapotranspiration over a long period of time. Thus, solutions to account for crop rotation in the implementation of SVAT models are discussed.

Garrigues, S.; Olioso, A.; Calvet, J.-C.; Lafont, S.; Martin, E.; Chanzy, A.; Marloie, O.; Bertrand, N.; Desfonds, V.; Renard, D.

2012-04-01

30

Climate-Soil-Vegetation Control on Groundwater Table Dynamics and its Feedbacks in a Climate Model  

SciTech Connect

Among the three dynamically linked branches of the water cycle, including atmospheric, surface, and subsurface water, groundwater is the largest reservoir and an active component of the hydrologic system. Because of the inherent slow response time, groundwater may be particularly relevant for long time-scale processes such as multi-years or decadal droughts. This study uses regional climate simulations with and without surface water – groundwater interactions for the conterminous U.S. to assess the influence of climate, soil, and vegetation on groundwater table dynamics, and its potential feedbacks to regional climate. Analysis shows that precipitation has a dominant influence on the spatial and temporal variations of groundwater table depth (GWT). The simulated GWT is found to decrease sharply with increasing precipitation. Our simulation also shows some distinct spatial variations that are related to soil porosity and hydraulic conductivity. Vegetation properties such as minimum stomatal resistance, and root depth and fraction are also found to play an important role in controlling the groundwater table. Comparing two simulations with and without groundwater table dynamics, we find that groundwater table dynamics mainly influences the partitioning of soil water between the surface (0 – 0.5 m) and subsurface (0.5 – 5 m) rather than total soil moisture. In most areas, groundwater table dynamics increases surface soil moisture at the expense of the subsurface, except in regions with very shallow groundwater table. The change in soil water partitioning between the surface and subsurface is found to strongly correlate with the partitioning of surface sensible and latent heat fluxes. The evaporative fraction (EF) is generally higher during summer when groundwater table dynamics is included. This is accompanied by increased cloudiness, reduced diurnal temperature range, cooler surface temperature, and increased cloud top height. Although both convective and non-convective precipitation are enhanced, the higher EF changes the partitioning to favor more non-convective precipitation, but this result could be sensitive to the convective parameterization used. Compared to simulations without groundwater table dynamics, the dry bias in the summer precipitation is slightly reduced over the central and eastern U.S. Groundwater table dynamics can provide important feedbacks to atmospheric processes, and these feedbacks are stronger in regions with deeper groundwater table, because the interactions between surface and subsurface are weak when the groundwater table is deep. This increases the sensitivity of surface soil moisture to precipitation anomalies, and therefore enhances land surface feedbacks to the atmosphere through changes in soil moisture and evaporative fraction. By altering the groundwater table depth, land use change and groundwater withdrawal can alter land surface response and feedback to the climate system.

Leung, Lai-Yung R.; Huang, Maoyi; Qian, Yun; Liang, Xu

2010-01-29

31

Impact of Hillslope-Scale Organization of Topography, Soil Moisture, Soil Temperature, and Vegetation on Modeling Surface Microwave Radiation Emission  

Microsoft Academic Search

Microwave radiometry will emerge as an important tool for global remote sensing of near-surface soil moisture in the coming decade. In this modeling study, we find that hillslope-scale topography (tens of meters) influences microwave brightness temperatures in a way that produces bias at coarser scales (kilometers). The physics underlying soil moisture remote sensing suggests that the effects of topography on

Alejandro N. Flores; Valeriy Y. Ivanov; Dara Entekhabi; Rafael L. Bras

2009-01-01

32

Modeling temporal and large-scale spatial variability of soil respiration from soil water availability, temperature and vegetation productivity indices  

Microsoft Academic Search

Field-chamber measurements of soil respiration from 17 different forest and shrubland sites in Europe and North America were summarized and analyzed with the goal to develop a model describing seasonal, interannual and spatial variability of soil respiration as affected by water availability, temperature, and site properties. The analysis was performed at a daily and at a monthly time step. With

Markus Reichstein; Ana Rey; Annette Freibauer; John Tenhunen; Riccardo Valentini; Joao Banza; Pere Casals; Yufu Cheng; Jose M. Grünzweig; James Irvine; Richard Joffre; Beverly E. Law; Denis Loustau; Franco Miglietta; Walter Oechel; Jean-Marc Ourcival; Joao S. Pereira; Alessandro Peressotti; Francesca Ponti; Ye Qi; Serge Rambal; Mark Rayment; Joan Romanya; Federica Rossi; Vanessa Tedeschi; Giampiero Tirone; Ming Xu; Dan Yakir

2003-01-01

33

Modelling temporal and large-scale spatial variability of soil respiration from soil water availability, temperature and vegetation productivity indices  

Microsoft Academic Search

Field-chamber measurements of soil respiration from 17 different forest and shrubland sites in Europe and North America were summarized and analyzed with the goal to develop a model describing seasonal, inter-annual and spatial variability of soil respiration as affected by water availability, temperature and site properties. The analysis was performed at a daily and at a monthly time step. With

M. Reichstein; A. Rey; A. Freibauer; J. Tenhunen; R. Valentini

2003-01-01

34

A multiyear evaluation of a Dynamic Global Vegetation Model at three AmeriFlux forest sites: Vegetation structure, phenology, soil temperature, and CO 2 and H 2O vapor exchange  

Microsoft Academic Search

We utilized eddy-covariance observations of carbon dioxide (CO2) and water vapor exchange at three AmeriFlux mid-latitude forest stands to evaluate IBIS, a Dynamic Global Vegetation Model (DGVM). Measurements of leaf area index (LAI), soil moisture and temperature, runoff, soil carbon (C), and soil respiration (R) were also compared with model output. An experimental approach was designed to help attribute model

Christopher J. Kucharik; Carol C. Barford; Mustapha El Maayar; Steven C. Wofsy; Russell K. Monson; Dennis D. Baldocchi

2006-01-01

35

Vegetation-soil water interaction within a dynamical ecosystem model of grassland in semi-arid areas  

NASA Astrophysics Data System (ADS)

A dynamical ecosystem model with three variables, living biomass, wilted biomass and available soil wetness, is developed to examine the vegetation-soil water interaction in semi-arid areas. The governing equations are based on the mass conservation law. The physical and biophysical processes are formulated with the parameters estimated from observational data. Both numerical results and qualitative analysis of the model as well as observational data indicate that the maintenance of a grassland requires a minimum precipitation (or equivalently, a minimum moisture index), and the grassland and desert ecosystem can coexist when precipitation is within a range above this threshold. Sensitivity studies show that these numerical results are robust with respect to model parameters and the transformation functions. It is also found that the wilted vegetation plays a very important role in shaping the transition between grassland and desert. By using the theories of an attractor basin and multiple equilibrium states, the conditions for grassland maintenance and the strategy of grazing are also analysed.

Zeng, Xiaodong; Zeng, Xubin; Shen, Samuel S. P.; Dickinson, Robert E.; Zeng, Qing-Cun

2005-07-01

36

Calibration and Uncertainty Analysis of Water and Solute Transport Models Within Vegetated Soils Using a Detailed Dataset  

NASA Astrophysics Data System (ADS)

Appropriate models predicting the fate and transport of water and dissolved chemicals in vegetated soils are required for a wide range of applications. Substantial uncertainty is present due to measurement errors, parametric uncertainty, and structural issues related to model conceptualisation. Due to the costs and intrusiveness of subsurface measurements there are limited datasets available to interrogate models against. Furthermore, the models are typically computationally intensive, making it difficult to fully explore parametric and other uncertainty spaces. Hence there are two pressing needs which must be met to improve the utility of models: more data and constraints are needed to quantify the interactions between different uncertainties and their overall impact on the reliability and robustness of model outputs, and efficient methodologies to explore sensitivities and uncertainties are also called for. This paper presents a combined analysis of a particularly detailed dataset and models of water and solute movement, using both simple random search and Markov chain Monte Carlo methods. Data was collected from an outdoor vegetated lysimeter facility over a duration of close to a year, with soil matric potential, moisture content and temperature at 10 cm depth intervals, along with rainfall and other meteorological variables, logged in four instrumented lysimeters at a time interval of 0.01 days. Three radionuclides (Na-22, Cl-36 and Cs-137) were supplied through the base of the lysimeters using an automated water table control system. Periodic soil cores and plant cuttings provided information on their migration and uptake. The integrity of the experimental data is examined, with uncertainty associated with outputs discussed and quantified. To interpret the data, a Richards' equation model coupled to a dynamic plant water model is linked to an advection-dispersion model with additional process representations of sorption, radioactive decay and root uptake. Structural uncertainty, parameterisation issues, and perturbation effects due to erroneous inputs are discussed. It is shown that although parameters are difficult to constrain in a univariate sense, consideration of model structure allows constraints on parametric interactions and hence a significant reduction of the parametric space that must be sampled. The efficiency of Markov Chain Monte Carlo techniques is demonstrated. However, despite the unusually comprehensive experimental dataset, major issues of uncertainty remain, of which data issues are a dominant component.

Jackson, B.; Wheater, H.; Butler, A.

2006-12-01

37

Constraining a physically based Soil-Vegetation-Atmosphere Transfer model with surface water content and thermal infrared brightness temperature measurements using a multiobjective approach  

Microsoft Academic Search

This article reports on a multiobjective approach which is carried out on the physically based Soil-Vegetation-Atmosphere Transfer (SVAT) model. This approach is designed for (1) analyzing the model sensitivity to its input parameters under various environmental conditions and (2) assessing input parameters through the combined assimilation of the surface water content and the thermal infrared brightness temperature. To reach these

Jérôme Demarty; Catherine Ottlé; Isabelle Braud; Albert Olioso; Jean Pierre Frangi; Hoshin V. Gupta; Luis A. Bastidas

2005-01-01

38

Soil feedback drives the mid-Holocene North African monsoon northward in fully coupled CCSM2 simulations with a dynamic vegetation model  

NASA Astrophysics Data System (ADS)

We explore climate-vegetation interactions in mid-Holocene North Africa with a suite of community climate system model (CCSM2) simulations. The CCSM includes synchronously coupled atmosphere, ocean, sea ice, land, and vegetation models. The CCSM’s present-day precipitation for North Africa compares well with simulations of other models and observations. Mid-Holocene data reveal a wetter and greener Sahara compared to the present. The CCSM exhibits a greater, closer to the expected, precipitation increase than other models, and in response, grasses advance from 18.75° to 22.5°N in much of North Africa. Precipitation is enhanced locally by the northward advance of grasses, but suppressed regionally mainly due to an insufficient albedo decrease with the expansion of vegetation. Prior studies have always lowered the surface albedo with the expansion of vegetation in North Africa. In the CCSM’s mid-Holocene simulations, the albedo decreases more because wetter soils are simulated darker than drier soils than due to expanding vegetation. These results isolate albedo as the key ingredient in obtaining a positive precipitation-vegetation feedback in North Africa. Two additional simulations support this conclusion. In the first simulation, the desert’s sandy soil textures are changed to loam to represent increased organic matter. Soil water retention and grass cover increase; albedo decreases somewhat. Precipitation responds with a small, yet widespread, increase. In the second simulation, a darker soil color is prescribed for this region. Now the monsoon advances north about 4°. These results illustrate a North African monsoon highly sensitive to changes in surface albedo and less sensitive to changes in evapotranspiration.

Levis, Samuel; Bonan, Gordon B.; Bonfils, Céline

2004-12-01

39

Designing a generalized soil-adjusted vegetation index (GESAVI)  

NASA Astrophysics Data System (ADS)

Operational monitoring of vegetative cover by remote sensing currently involves the utilization of vegetation indices (VIs), most of them being functions of the reflectance in red (R) and near-infrared (NIR) spectral bands. A generalized soil-adjusted vegetation index (GESAVI), theoretically based on a simple vegetation canopy model, is introduced. It is defined in terms of the soil line parameters (A and B) as: GESAVI equals (NIR-BR-A)/(R + Z), where Z is related to the red reflectance at the cross point between the soil line and vegetation isolines. Z can be considered as a soil adjustment coefficient which let this new index be considered as belonging to the SAVI family. In order to analyze the GESAVI sensitivity to soil brightness and soil color, both high resolution reflectance data from two laboratory experiments and data obtained by applying a radiosity model to simulate heterogeneous vegetation canopy scenes were used. VIs (including GESAVI, NDVI, PVI and SAVI family VIs) were computed and their correlation with LAI for the different soil backgrounds was analyzed. Results confirmed the lower sensitivity of GESAVI to soil background in most of the cases, thus becoming the most efficient index. This good index performance results from the fact that the isolines in the NIR-R plane are neither parallel to the soil line (as required by the PVI) nor convergent at the origin (as required by the NDVI) but they converge somewhere between the origin and infinity in the region of negative values of both NIR and R. This convergence point is not necessarily situated on the bisectrix, as required by other SAVI family indices.

Gilabert, M. A.; Gonzalez-Piqueras, Jose; Garcia-Haro, F. J.; Melia, J.

1998-12-01

40

Soil moisture-vegetation-precipitation feedback over North America: Its sensitivity to soil moisture climatology  

NASA Astrophysics Data System (ADS)

Our previous studies examined how vegetation feedback at the seasonal time scale influenced the impact of soil moisture anomalies (SMAs) on subsequent summer precipitation with a modified version of the coupled Community Atmosphere Model-Community Land Model 3 that includes a predictive phenology scheme. Here we investigate the climatology sensitivity of soil moisture-vegetation-precipitation feedback using the same model as the baseline model (BASE) and its derivative with modifications to the model runoff parameterization as the experiment model (EXP), in which we eliminate the subsurface lateral drainage to reduce the known dry biases of BASE. With vegetation feedback ignored, precipitation is more sensitive to wet SMAs than dry SMAs in BASE; opposite to BASE, the wetter mean soil moisture in EXP leads to higher sensitivity of precipitation to dry SMAs than to wet SMAs. However, in both BASE and EXP, the impact of dry SMAs on subsequent precipitation persists longer than the impact of wet SMAs. With vegetation feedback included, EXP shows a positive feedback between vegetation and precipitation following both dry and wet SMAs in summer, while BASE shows a positive feedback following wet SMAs only, with no clear signal following dry SMAs due to dry soil biases. In BASE, the magnitude of precipitation changes due to vegetation feedback is comparable to that due to soil moisture feedback when more realistic SMAs are applied. In addition, a major difference is found in spring when the vegetation impact on subsequent precipitation is negative and significant in BASE, but not significant in EXP.

Kim, Yeonjoo; Wang, Guiling

2012-09-01

41

N 2 O and NO emission from agricultural fields and soils under natural vegetation: summarizing available measurement data and modeling of global annual emissions  

Microsoft Academic Search

The number of published N2O and NO emissions measurements is increasing steadily, providing additional information about driving factors of these emissions and allowing an improvement of statistical N-emission models. We summarized information from 1008 N2O and 189 NO emission measurements for agricultural fields, and 207 N2O and 210 NO measurements for soils under natural vegetation. The factors that significantly influence

Elke Stehfest; Lex Bouwman

2006-01-01

42

Groundwater–soil water–vegetation dynamics in a temperate forest ecosystem along a slope  

Microsoft Academic Search

Groundwater can have a profound effect on water availability to vegetation in temperate climate regions. Here we attempt to model groundwater, soil water, and vegetation dynamics in groundwater controlled ecosystems and to assess how these depend on climate and topography. We focus on the possible location of a boundary between two vegetation types on a slope. One vegetation type is

R. J. Brolsma; M. F. P. Bierkens

2007-01-01

43

Groundwater-soil water-vegetation dynamics in a temperate forest ecosystem along a slope  

Microsoft Academic Search

Groundwater can have a profound effect on water availability to vegetation in temperate climate regions. Here we attempt to model groundwater, soil water, and vegetation dynamics in groundwater controlled ecosystems and to assess how these depend on climate and topography. We focus on the possible location of a boundary between two vegetation types on a slope. One vegetation type is

R. J. Brolsma; M. F. P. Bierkens

2007-01-01

44

INTERACTION OF VEGETATION AND SOIL FROST PHENOMENA?  

Microsoft Academic Search

N northern lands special problems presented by frost in soils are receiving more and more attention as the pace of construction and settlement increases. Investigations aimed primarily at these problems, notably that of permafrost, have partially revealed the composition and mechanisms of the severe frost climate1 environment. Parts of this environment owe their nature to the influence of vegetation and

William S. Benninghoff

45

FASST Vegetation Models.  

National Technical Information Service (NTIS)

The one-dimensional dynamic state of the ground model FASST (Fast All-season Soil Strength) is a state of the ground model developed by Frankenstein and Koenig (2004) as part of the Army's Battlespace Terrain Reasoning and Awareness (BTRA) research progra...

S. Frankenstein G. Koenig

2004-01-01

46

Chapter 3 Vegetation, organic matter and soil quality  

Microsoft Academic Search

Soil life depends on water, inorganic chemical elements and organic matter. Due to photosynthesis there is the growth of vegetation, primary production. The role of vegetation and humus in relation to their function and the many characteristics of their composition have been described in relation to soil quality and soil health. Soil is an environmental component and is permanently changing

W. H. O. Ernst

2004-01-01

47

Soil depth constrains whether evapotranspiration contrasts between vegetation types  

NASA Astrophysics Data System (ADS)

Altering vegetation types in semiarid ecosystems has been proposed as a method for managing evapotranspiration (ET). In adjacent sites with contrasting vegetation types, ET is controlled by available energy (net radiation minus storage heat flux), which is largely a function of ecosystem composition and structure, and on how that available energy is partitioned between latent and sensible heat flux. Available energy in woodlands, for example, is typically higher than in grasslands because woodlands absorb more radiant energy. The partitioning of available energy between latent and sensible heat is controlled to a large degree by water availability. In shallow soil systems, however, roots of both grasses and trees are confined and water storage capacity is limited, which may result in lower latent and higher sensible heat than what would occur in deeper soil systems. In a semiarid system underlain by limestone, we compared energy balance partitioning and ET among a continuum of vegetation types: grassland (G), oak savanna (S), and juniper-oak woodland (W). We expect differences among sites to be most pronounced during drought in areas with deep soil because nearly all available energy should transfer to latent heat when adequate moisture is available, regardless of vegetation type. Root depth may differ by species in deep soils, but may only differ in shallow soils if roots penetrate into fractured limestone below the soil horizon. Three adjacent sites (G, S, W) were monitored for ET using the eddy covariance method. Soil depths are approximately 0.5 m at G, 1 m at S, and 0.2 m at W. Trees were equipped with sapflow sensors to monitor species differences in dry down response. Measurements showed that available energy was highest in the woodland, and lowest in the grassland. However, ET was highest in the savanna, the site with the deepest soil. Total ET over a 2-yr period was 1319 mm, 1465 mm, and 1409 mm, respectively at G, S, and W sites. The highest sensitivity of ET to rainfall and water deficits was observed in the woodland, the site with the greatest woody cover, but the thinnest soil. Transpiration in oak in the woodland was more sensitive to precipitation events than juniper. The least sensitivity of ET to rainfall and water deficits was observed in the savanna, the site with the deepest soil. A separate experiment at a new location was conducted to examine root water uptake differences between grass and juniper plots in very deep soils (>1 m) and to calibrate a soil water balance model. The model was then used to simulate changes in uptake with varying soil depth. Deep soils under juniper were depleted of moisture much faster than deep soils under grass, resulting in very large cumulative annual differences (10 times) in water loss between the two vegetation types. However, a model of this system with soil depth constrained to only the top 10 cm (a common occurrence) predicts that differences would be much smaller, only 40% annually. It follows for this semiarid ecosystem underlain by limestone that spatial patterns in ET are dependent upon both vegetation type and soil depth variation.

Moore, G. W.; Heilman, J. L.; Rebel, K. T.; Owens, M. K.; Litvak, M. E.; Nero, B. F.

2009-04-01

48

Online vegetation parameter estimation using passive microwave observations for soil moisture estimation  

Technology Transfer Automated Retrieval System (TEKTRAN)

Vegetation affects the ability to estimate soil moisture from passive microwave observations by attenuating the surface soil moisture signal. To use radiobrightness observations in land data assimilation a vegetation opacity parameter is required as input to a radiative transfer model, which maps su...

49

Mapping the vegetation of Kuwait through reconnaissance soil survey  

Microsoft Academic Search

Previous studies on the vegetation of Kuwait showed dominance of five plant communities; however, due to both natural and human factors, the vegetation has been altered. In the present study, a vegetation map was prepared by integrating soil information and vegetation information in a Geographic Information System (GIS). A reconnaissance field survey was conducted at scale 1:100,000 for the entire

Samira A. S. Omar; Rafat Misak; Peter King; Shabbir A. Shahid; Haana Abo-Rizq; Gerard Grealish; Waleed Roy

2001-01-01

50

Correspondence between Vegetation and Soils in Wetlands and Nearby Uplands  

Microsoft Academic Search

The association between vegetation and soils from a geographically broad sampling of wetlands and adjoining uplands is reported\\u000a for 38 hydric and 26 nonhydric soils, as recognized in the hydric soils list of the Soil Conservation Service. Wetlands represented\\u000a in the study include estuaries, pitcher plant bogs, prairie depressional wetlands, and western riparian lands. The agreement\\u000a between vegetation and soils

Michael L. Scott; William L. Slauson; Charles A. Segelquist; Gregor T. Auble

1989-01-01

51

Soil-Vegetation Correlations in Coastal Mississippi Wetlands,  

National Technical Information Service (NTIS)

As part of a national study, vegetation associated with known hydric soil series was sampled on the Mississippi Sandhill Crane National Wildlife Refuge in southern Mississippi. Weighted average values were calculated for vegetation associations on each so...

N. E. Erickson D. M. Leslie

1988-01-01

52

Aluminium binding by leached dissolved organic matter in acidic forest soils: modelling study of variations in time, space and vegetation age of the binding properties.  

NASA Astrophysics Data System (ADS)

Knowledge of aluminium (Al) speciation in soil and surface waters is important for a number of environmental issues in relation to ecosystem acidification, such as water quality and the availability of nutrients in acidic soils. Dissolved organic matter (DOM) and especially humic substances (HS) are recognised as an important complex former of Al. Numerical models enabling the simulation of the amount of organically-bound metals (OBM) on a mechanistic basis have been developed and used in a natural context. Parameter optimisation, generally by scaling the density of binding sites, is often required to match measured values of OBM because of the difficulties in determining the actual binding properties of HS. Such an adjustment can serve as a method to determine the actual binding properties of HS. Here, we have used the WHAM model to study the variations in HS properties from the chemistry of leaching solutions and measured values of organically-bound Al corresponding to different soil horizons, time and vegetation age. Results are discussed in regard to literature data.

Gerard, F.; Jaffrain, J.; Huybretch, F.; Boudot, J. P.; Tinsley, M.; Ranger, J.

2003-04-01

53

Thermal Remote Sensing of Surface Soil Water Content with Partial Vegetation Cover for Incorporation into Climate Models  

Microsoft Academic Search

This study outlines a method for the estimation of regional patterns of surface moisture availability (M0) and fractional vegetation (Fr) in the presence of spatially variable vegetation cover. The method requires relating variations in satellite-derived (NOAA, Advanced Very High Resolution Radiometer) surface radiant temperature to a vegetation index (computed from satellite visible and near-infrared data) while coupling this association to

Robert R. Gillies; Toby N. Carlson

1995-01-01

54

An Overview of the Use of the SimSphere Soil Vegetation Atmosphere Transfer (SVAT) Model for the Study of Land-Atmosphere Interactions  

PubMed Central

Soil Vegetation Atmosphere Transfer (SVAT) models consist of deterministic mathematical representations of the physical processes involved between the land surface and the atmosphere and of their interactions, at time-steps acceptable for the study of land surface processes. The present article provides a comprehensive and systematic review of one such SVAT model suitable for use in mesoscale or boundary layer studies, originally developed by [1]. This model, which has evolved significantly both architecturally and functionally since its foundation, has been widely applied in over thirty interdisciplinary science investigations, and it is currently used as a learning resource for students in a number of educational institutes globally. The present review is also regarded as very timely, since a variation of a method using this specific SVAT model along with satellite observations is currently being considered in a scheme being developed for the operational retrieval of soil surface moisture by the US National Polar-orbiting Operational Environmental Satellite System (NPOESS), in a series of satellites that are due to be launched from 2016 onwards.

Petropoulos, George; Carlson, Toby N.; Wooster, Martin J.

2009-01-01

55

Assessing the effect of vegetation in the estimation of soil properties with field VNIR radiometry  

NASA Astrophysics Data System (ADS)

Spectroradiometric soil surveys (field radiometry) are a valuable technique for soil classification and properties estimation. Field radiometry combines -in a relatively easy-to-use procedure- a fast, accurate and non-destructive sampling method. A wide range of soil properties have been quantitatively estimated with field or laboratory radiometry. In addition, field radiometry is a basic stage in remote sensing studies. It allows the up-scaling process of soil, vegetation or water parameters from the ground level to the airborne or spaceborne sensors level. Field radiometry plays a crucial role in training and validation stages of quantitative remote sensing. A complex problem in remote sensing appears when several components are mixed within a pixel and the resulting pixel's spectrum is a combination of the individual components. This work assess the effect of vegetation in soil properties estimation with linear regression models. Field spectra were taken from soil-vegetation mixtures under natural illumination with a portable spectroradiometer in the visible and near-infrared (VNIR) spectral range. Soil and vegetation samples for each radiometric sampling point were taken and analyzed in laboratory. Soil moisture content and soil organic carbon measured by the LOI (Loss-On-Ignition) method (Konen et al. 2002) were used in this approach. A derivative analysis of field spectra was used to determine the position and magnitude of absorption bands according to the method employed by Melendez-Pastor et al. (2008). Pearson correlations between soil parameters and each spectral band were computed and correlograms for the first and second derivate were obtained. Maximum (approximates to +1) and minimum (approximates to -1) Pearson correlations were used to normalize correlograms between 0 to 1. High relatively correlated bands (with values ranging from 0 to 0.1 or from 0-9 to 1 for the normalized correlograms) were identified and used as explicative variables in the regression models. In addition, vegetation water content and the NDVI (Normalized Difference Vegetation index) computed from field spectra also were used as explicative variables. Four combinations of explicative variables were used to predict soil variables: 1) high correlated bands, 2) high correlated bands and a soil parameter (LOI is used to predict soil moisture and vice versa), 3) high correlated bands and vegetation parameters, and 4) high correlated bands with soil and vegetation parameters. Models were developed for LOI and soil moisture with the first and second derivate. Medium to high correlation coefficients (R) were obtained in all regression models. R values ranged from 0.7 for the first approach (just high correlated bands) to 0.9 for the prediction of soil moisture with high correlated bands of the second derivate with vegetation parameters. Regression models with the second derivative achieved better model's adjustments and were almost equal for all combinations of explicative variables. A small improvement was observed for first derivate regression models using soil and vegetation explicative variables. Vegetation moisture was the most important parameter for the improvement of soil properties estimation. The combined used of soil and vegetation parameters for quantitative remote sensing of soil parameters allows accuracy improvements and a better knowledge of land cover mixtures. Regression models with the second derivate spectral peaks are less sensitive to changes in the vegetation coverage and thus retrieves better soil parameters estimations. References Konen, M., P. Jacobs, C. Lee Burras, B. Talaga, J. Mason. (2002) Equations for predicting soil organic carbon using loss-on-ignition for north central U.S. soils. Soil Science Society of America Journal, 66:1878-1881. Melendez-Pastor, I., J. Navarro-Pedreño, I. Gómez, M. Koch. (2008). Identifying optimal spectral bands to assess soil properties with VNIR radiometry in semi-arid soils. Geoderma, 147: 126-132.

Melendez-Pastor, I.; Córdoba-Sola, P.; Navarro-Pedreño, J.; Gómez, I.; Koch, M.

2009-04-01

56

Estimation and monitoring of bare soil\\/vegetation ratio with SPOT Vegetation and HRVIR  

Microsoft Academic Search

Leaving fields with a vegetation cover during the winter is one of the main ways to reduce water pollution, in re- stricting pollutant fluxes towards rivers. The bare soils\\/vegetation ratio monitoring can be carried out daily at a coarse spatial resolution with SPOT VEGETATION (1 km), and also at a higher spatial resolution with SPOT HRVIR (20 m), but with

Laurence HUBERT-MOY Thomas HOUET; CNRS FRE

57

Transregional Collaborative Research Centre 32: Patterns in Soil-Vegetation  

NASA Astrophysics Data System (ADS)

The soil, vegetation and the lower atmosphere (SVA) are key compartments of the Earth, where almost all activities of mankind take place. This region is characterized by extremely complex patterns, structures and processes that act at different temporal and spatial scales. While the exchange of energy, water and carbon is continuous between the different compartments, the pertinent fluxes are strongly heterogeneous and variable in space and time. The overarching TR32 paradigm is that the characterisation of structures and patterns will lead to a deeper qualitative and quantitative understanding of the SVA system, and ultimately to better predictions of the SVA state. The TR32 combines research groups in the field of soil and plant science, remote sensing, hydrology, meteorology and mathematics located at the Universities of Aachen, Bonn, Braunschweig and Cologne and the Research Centre Juelich study the soil-vegetation atmosphere system under the novel holistic paradigm of patterns. To understand the mechanisms leading to spatial and temporal patterns in energy and matter fluxes of the SVA system we link experiments and theory via model-observation integration. Focusing our research on the Rur Catchment (Germany), patterns are monitored since 2006 continuously using existing and novel geophysical and remote sensing techniques from the local to the catchment scale based on ground penetrating radar methods, induced polarization, radiomagnetotellurics, electrical resistivity tomography, boundary layer scintillometry, lidar techniques, microwave radiometry, and precipitation radars with polarization diversity. Modeling approaches involve high resolution numerical weather prediction (NWP; 400m) and hydrological models (few meters). Example work from the first phase includes the transfer of laboratory methods to the field; the measurements of patterns of soil-carbon, evapotranspiration and respiration measured in the field; catchment-scale modeling of exchange processes and the setup of an atmospheric boundary layer monitoring network. In the second phase (2011-2014), the focus is on the integration of models from the groundwater to the atmosphere for both the m- and km-scale and the extension of the experimental monitoring in respect to vegetation. The general coupled modeling concept is based on the atmospheric model COSMO, the land surface model CLM and the hydrological model ParFlow. In order to bridge the scale gaps in measurements and modelling an LES model will be validated via a dedicated field campaign.

Kollet, S. J.; Simmer, C.; Masbou, M.; Boessenkool, K.; Crewell, S.; Diekkruger, B.; Huber, K.; Klitzsch, N.; Koyama, C. N.; Vereecken, H.

2011-12-01

58

Soil microbial properties under different vegetation types on Mountain Han.  

PubMed

This study investigated the influence of broadleaf and conifer vegetation on soil microbial communities in a distinct vertical distribution belt in Northeast China. Soil samples were taken at 0-5, 5-10 and 10-20 cm depths from four vegetation types at different altitudes, which were characterized by poplar (Populus davidiana) (1250-1300 m), poplar (P. davidiana) mixed with birch (Betula platyphylla) (1370-1550 m), birch (B. platyphylla) (1550-1720 m), and larch (Larix principis-rupprechtii) (1840-1890 m). Microbial biomass and community structure were determined using the fumigation-extraction method and phospholipid fatty acid (PLFA) analysis, and soil fungal community level physiological profiles (CLPP) were characterized using Biolog FF Microplates. It was found that soil properties, especially soil organic carbon and water content, contributed significantly to the variations in soil microbes. With increasing soil depth, the soil microbial biomass, fungal biomass, and fungal catabolic ability diminished; however, the ratio of fungi to bacteria increased. The fungal ratio was higher under larch forests compared to that under poplar, birch, and their mixed forests, although the soil microbial biomass was lower. The direct contribution of vegetation types to the soil microbial community variation was 12%. If the indirect contribution through soil organic carbon was included, variations in the vegetation type had substantial influences on soil microbial composition and diversity. PMID:23737003

Wang, Miao; Qu, Laiye; Ma, Keming; Yuan, Xiu

2013-06-05

59

Soil aggregate stability under different Mediterranean vegetation types  

Microsoft Academic Search

The influence of vegetation type on soil erodibility was studied by means of aggregate stability measurements using the Modified Emerson Water Dispersion Test (MEWDT), water-drop impacts (CND and TDI) and Ultrasonic Disruption (UD) methods on soils from north-facing slopes of the mountain range of La Serra Grossa in the eastern Iberian Peninsula. Soils with similar characteristics but covered by the

A. Cerda

1998-01-01

60

A Comparison between Active and Passive Sensing of Soil Moisture from Vegetated Terrains  

Microsoft Academic Search

A comparison between active and passive sensing of soil moisture over vegetated areas is studied via scattering models. In active sensing, three contributing terms to radar backscattering can be identified: 1a) the ground surface scatter term; 2a) the volume scatter term representing scattering from the vegetation layer; and 3a) the surfacevolume. scatter term accounting for scattering from both surface and

ADRIAN K. FUNG; Hyo Eom

1985-01-01

61

Patterns and Processes in Southwestern shrublands and grasslands: role of vegetation, soil- geomorphology, and overland flow  

NASA Astrophysics Data System (ADS)

Pattern of variable soil properties have been linked to vegetation as well as soil-landform characteristics and processes. It has been long hypothesized that patterns of infiltration and overland flow play key roles in arid and semi-arid region ecohydrology. Specifically, the process of redistribution of water and sediments have been linked to vegetation related feedbacks that enable persistence of vegetation in water limited environments. Yet, the processes of redistribution, such as through runoff and surface ponding, have been poorly described or documented. We have documented that the spatial pattern of soil properties is dependant on the vegetation pattern as well as the type of, and in some cases location within a, landform. These patterns are likely due to feedbacks between vegetation and the surface processes that affect soil properties and therefore water availability. In this paper, we present observations and numerical simulation that show how patterns of overland flow and infiltration are affected by vegetation-topography related patterns of soil properties. We have developed a numerical model that works on 10 cm grid cells that can inform on the processes of infiltration and overland flow over continuously varying soil properties. We use this model to show how the patterns of soil properties affect runoff, as well as the conditions under which redistribution via runon and ponding can occur. Furthermore, we show using data from a central New Mexico grassland and shrubland, and an eastern Mojave Desert shrubland how climatic differences can affect the patterns of infiltration and runoff.

Bedford, D. R.; Small, E. E.; E, T. G.

2007-12-01

62

Soil carbon and soil nitrogen changes after clearing of mulga vegetation  

Microsoft Academic Search

Mulga (Acacia aneura) dominated vegetation originally occupied 11.2 million hectares in Queensland, of which 12% has been cleared. Clearing of mulga vegetation, and altered land use for a period of 20 years has caused a significant decline in soil carbon (C) and nitrogen (N) at the study site in southern Queensland. Soil C in the top 0.05 m of soil

Ben Harms; Ram Dalal; Weijin Wang

63

[Soil faunal diversity under typical alpine vegetations in West Sichuan].  

PubMed

In order to understand the variations of soil faunal diversity under different natural alpine vegetations in West Sichuan, an investigation was made on the soil faunal communities under alpine coniferous forest, shrub, and meadow from August 2008 to June 2009. A total of 48343 individuals were collected, belonging to 7 phyla, 16 classes, 31 orders and 117 families. There was a great difference in the dominant groups of soil macro-fauna, and a significant difference (P < 0.05) in the number of soil faunal groups under different vegetations. Both the individual density and the group number of soil fauna decreased obviously with increasing soil depth, and were significantly higher (P < 0.01) in moss layer than in litter layer in coniferous forest. Significant difference (P < 0.01) was also observed in the density-group index among the three vegetations. The maximum biomass of soil macro-fauna was found in June. Jacard indices indicated that disturbed meadow had the lowest similarity of soil faunal community with the other vegetations. It was suggested that vegetation type had significant effects on the community structure of soil fauna, while aspect, altitude, and disturbance also had definite effects. PMID:20387441

Huang, Xu; Wen, Wei-Quan; Zhang, Jian; Yang, Wan-Qin; Liu, Yang; Yan, Bang-Guo; Huang, Yu-Mei

2010-01-01

64

A Vegetated Urban Canopy Model for Meteorological and Environmental Modelling  

NASA Astrophysics Data System (ADS)

An urban canopy model is developed for use in mesoscale meteorological and environmental modelling. The urban geometry is composed of simple homogeneous buildings characterized by the canyon aspect ratio ( h/ w) as well as the canyon vegetation characterized by the leaf aspect ratio (? l ) and leaf area density profile. Five energy exchanging surfaces (roof, wall, road, leaf, soil) are considered in the model, and energy conservation relations are applied to each component. In addition, the temperature and specific humidity of canopy air are predicted without the assumption of thermal equilibrium. For radiative transfer within the canyon, multiple reflections for shortwave radiation and one reflection for longwave radiation are considered, while the shadowing and absorption of radiation due to the canyon vegetation are computed by using the transmissivity and the leaf area density profile function. The model is evaluated using field measurements in Vancouver, British Columbia and Marseille, France. Results show that the model quite well simulates the observations of surface temperatures, canopy air temperature and specific humidity, momentum flux, net radiation, and energy partitioning into turbulent fluxes and storage heat flux. Sensitivity tests show that the canyon vegetation has a large influence not only on surface temperatures but also on the partitioning of sensible and latent heat fluxes. In addition, the surface energy balance can be affected by soil moisture content and leaf area index as well as the fraction of vegetation. These results suggest that a proper parameterization of the canyon vegetation is prerequisite for urban modelling.

Lee, Sang-Hyun; Park, Soon-Ung

2008-01-01

65

Effect of lead arsenate in soil on vegetables  

Microsoft Academic Search

Experiments were performed to determine what effects lead arsenate added to soils had on the germination, growth, and yield of garden vegetables. The vegetables used were asparagus, broccoli, brussels sprouts, cabbage, carrots, cauliflower, corn, popcorn, pepper, cucumber, eggplant, endive, kohlrabi, lettuce, okra, onion, parsley, parsnip, pea, pumpkin, radish, squash, tomato, turnip, watermelon, beets, muskmelon, spinach, lima beans, and string beans.

W. E. Fleming; F. E. Baker; L. Koblitsky

1943-01-01

66

Salix vegetation filters for purification of waters and soils  

Microsoft Academic Search

During recent years it has become obvious that it is both environmentally and economically appropriate to use vegetation filters of short rotation willows (Salix spp.) to purify waters and soils. Swedish and Polish experiences of vegetation filter efficiencies have been demonstrated in several laboratory, field lysimeter and full-scale experiments. However, there are still many questions to be answered; for example,

K. L. Perttu; P. J. Kowalik

1997-01-01

67

Soil moisture and vegetation controls on evapotranspiration in a heterogeneous Mediterranean ecosystem on Sardinia, Italy  

Microsoft Academic Search

Micrometeorological measurements of evapotranspiration (ET) can be difficult to interpret and use for validating model calculations in the presence of land cover heterogeneity. Land surface fluxes, soil moisture ($\\\\theta$), and surface temperatures (Ts) data were collected by an eddy correlation-based tower located at the Orroli (Sardinia) experimental field (covered by woody vegetation, grass, and bare soil) from April 2003 to

Matteo Detto; Nicola Montaldo; John D. Albertson; Marco Mancini; Gaby Katul

2006-01-01

68

Integrating dynamic soil and vegetation properties into ecosystem service-based state and transition models to guide rangeland management  

Technology Transfer Automated Retrieval System (TEKTRAN)

California’s annual rangelands cover approximately 6.4 million hectares, and produce 70% of the state’s forage base. This ecosystem supports more than 300 vertebrate, 5000 invertebrate, and 2000 plant species. Annual rangeland soils have the capacity to support high primary productivity, accumulate ...

69

The Effects of Vegetation Parameter Aggregation on Modeled Evapotranspiration  

NASA Astrophysics Data System (ADS)

The effects of the scale of vegetation parameter aggregation on modeled evapotranspiration pattern and rate are explored. The vegetation parameters used are vegetation biomass, height and fractional coverage per model grid cell. A spatially explicit hydrologic model is executed for a catchment scale watershed (11.6 km2) from the FIFE dataset. The dominant vegetation coverage over the catchment is prairie grass. Distributed vegetation parameters were taken from vegetation indices developed from satellite remote sensing images of the catchment. Evapotranspiration pattern is correlated with a remotely sensed surface brightness temperature image to assess the homogenization effects of vegetation parameter aggregation. Catchment averaged evapotranspiration rate simulated at a range of aggregation scales is compared with measurements to determine loss of calibration in the model during the simulation as a function of aggregation scale. The results from model simulations for pattern show degradation of evapotranspiration pattern up to a scale of 0.2 square kilometers of vegetation parameter aggregation, after which no further degradation was observed. The degradation of pattern consequently modifies the soil moisture availability in the root zone for each simulation case. Vegetation parameter aggregation was found not to affect the simulated catchment averaged evapotranspiration rate during energy limited conditions. However, the simulated catchment averaged evapotranspiration rate during moisture limited conditions (i.e., when ET is non-linearly related to soil moisture) is affected by parameter aggregation due to changes in the root zone soil moisture induced by homogenization of the evapotranspiration pattern. Change in simulated catchment averaged evapotranspiration rate during moisture limited conditions is observed, like the degradation of the pattern, up to a scale of 0.2 square kilometers. Thus, vegetation parameter aggregation is shown to indirectly affect the simulated spatially averaged evapotranspiration rate through the non-linearity of the soil moisture feedback.

Hoffpauir, R. J.; Over, T. M.

2001-05-01

70

Transfer of Cadmium from Soil to Vegetable Crops  

Microsoft Academic Search

A pot experiment was conducted in order to study the transfer of Cd from soil to the vegetable crops namely Lettuce (Lactuca sativa L.), Spinach (Spinacia oleracea L.), Lal sak (Amaranthus tricolor L.) and Data sak (Amaranthus spinosis L.). The mean transfer factors (concentration in plant dry weight \\/ concentration in soil dry weight) varied from 2.030 to 6.785 in

M. Z. Hossain; S. M. Ullah; S. A. Ahad; M. B. Ullah

2007-01-01

71

Microwave Backscatter Dependence on Surface Roughness, Soil Moisture, and Soil Texture: Part II-Vegetation-Covered Soil  

Microsoft Academic Search

Results are presented of an experimental investigation to determine the relationship between radar backscatter coefficient ¿° and soil moisture for vegetation-covered soil. These results extend a previous report which showed the experimental relationship between ¿° and soil moisture for bare soil [1]. It is shown that the highest correlation between ¿° and soil moisture is 0.92 for the combined response

Fawwaz Ulaby; Gerald Bradley; Myron Dobson

1979-01-01

72

The variation of soil temperature and water content of seasonal frozen soil with different vegetation coverage in the headwater region of the Yellow River, China  

NASA Astrophysics Data System (ADS)

The variation and distribution of temperature and water moisture in the seasonal frozen soil is an important factor in the study of both the soil water cycle and heat balance within the source region of the Yellow River, especially under the different conditions of vegetation coverage. In this study, the impact of various degrees of vegetation coverage on soil water content and temperature was assessed. Soil moisture ( ? v) and soil temperature ( T s) were monitored on a daily basis. Measurements were made under different vegetation coverage (95, 70 80, 40 50 and 10%) and on both thawed and frozen soils. Contour charts of T s and ? v as well as a ? v T s coupling model were developed in order to account for the influence of vegetation cover and the interaction between T s and ? v. It was observed that soil water content affected both the overall range and trend in the soil temperature. The regression analysis of ? v versus T s plots indicated that the soil freezing and thawing processes were significantly affected by vegetation cover changes. Vegetation coverage changes also caused variations in the ? v T s interaction. The effect of soil water content on soil temperature during the freezing period was larger than during the thawing period. Moreover, the soil with higher vegetation coverage retained more water than that with lower coverage. In the process of freezing, the higher vegetation coverage reduced the rate of the reduction in the soil temperature because the thermal capacity of water is higher than that of soil. Areas with higher vegetation coverage also functioned better for the purpose of heat-insulating. This phenomenon may thus play an important role in the environmental protection and effective uses of frozen soil.

Cheng, Huiyan; Wang, Genxu; Hu, Hongchang; Wang, Yibo

2008-06-01

73

A Vegetated Urban Canopy Model for Meteorological and Environmental Modelling  

Microsoft Academic Search

An urban canopy model is developed for use in mesoscale meteorological and environmental modelling. The urban geometry is\\u000a composed of simple homogeneous buildings characterized by the canyon aspect ratio (h\\/w) as well as the canyon vegetation characterized by the leaf aspect ratio (?\\u000a l\\u000a ) and leaf area density profile. Five energy exchanging surfaces (roof, wall, road, leaf, soil) are

Sang-Hyun Lee; Soon-Ung Park

2008-01-01

74

QuickBird derived vegetation parameters for soil erosion risk assessment in an alpine catchment  

NASA Astrophysics Data System (ADS)

The focus of soil erosion research in the Alps has been in two categories: (i) on-site measurements which are rather small scale point measurements on selected plots often constrained to irrigation experiments or (ii) off-site quantification of sediment delivery at the outlet of the catchment. Results of both categories showed that an intact vegetation cover prevents soil loss. With the recent availability of high-resolution satellites such as IKONOS and QuickBird options for detecting and monitoring of vegetation parameters have increased. The aim of this study is to evaluate the usefulness of QuickBird derived vegetation parameters in soil erosion models by comparison to Cesium-137 (Cs-137) soil erosion estimates. The study site (67km2) is located in the Central Swiss Alps and is dominated by grasslands with strong anthropogenic influences due to farming for centuries. Linear spectral unmixing and supervised classification is applied to produce maps of fractional vegetation cover (FVC) for grasslands and detailed land-cover maps from QuickBird imagery. The maps are used to adapt the C factor, which accounts for land management in the Universal Soil Loss Equation (USLE). Further the data was introduced to the Pan-European Soil Erosion Risk Assessment (PESERA) model. Supervised land-cover classification yielded a total accuracy of 93.3%. Linear spectral unmixing of vegetation abundance showed a significant (at the 0.01 level) correlation to ground truth FVC. Both models yielded higher absolute soil erosion estimates and an improvement of spatial patterns when FVC and a detailed land-cover maps are considered. However, discrepancies between model estimates and Cs-137 erosion estimates remained, especially for the PESERA model. This is leading to the assumption that soil erosion processes not considered in the models, e.g. soil erosion caused by snow gliding, play a decisive role.

Meusburger, Katrin; Konz, Nadine; Schaub, Monika; Alewell, Christine

2010-05-01

75

Sensitivity of Mesoscale Surface Dynamics to Surface Soil and Vegetation Contrasts over the Carolina Sandhills  

Microsoft Academic Search

A region of contrasting soils exists over the Carolinas region of the southeastern United States. Previous research has shown\\u000a an increase in mesoscale summertime precipitation over this region. Numerical simulations are analyzed to investigate the\\u000a relationships between mesoscale surface dynamics and the transition from clay to sandy soils over this region. Numerical modeling\\u000a experiments using four different soil and vegetation

Ryan Boyles; Sethu Raman; Aaron Sims

2007-01-01

76

Occurrence and source analysis of typical veterinary antibiotics in manure, soil, vegetables and groundwater from organic vegetable bases, northern China.  

PubMed

The residue of antibiotics is becoming an intractable environmental problem in many organic vegetable bases. However, their residual levels and distribution are still obscure. This work systematically analyzed the occurrence and migration of typical veterinary antibiotics in organic vegetable bases, northern China. The results showed that there was no obvious geographical difference in antibiotic distribution between soil and manure. A simple migration model can be easy and quick to predict the accumulation of antibiotics in soil. Antibiotics were mainly taken up through water transport and passive absorption in vegetables. The distribution of antibiotics in a plant was in the sequence leaf>stem>root, and performed biological accumulation. The residues of antibiotics in all samples in winter were significantly higher than those in summer. Overall, this work can lay the foundation for understanding ecological risk of antibiotics and their potential adverse effects on human health by food chain. PMID:20580472

Hu, Xiangang; Zhou, Qixing; Luo, Yi

2010-06-30

77

Scaling dimensions in spectroscopy of soil and vegetation  

NASA Astrophysics Data System (ADS)

The paper revises and clarifies definitions of the term scale and scaling conversions for imaging spectroscopy of soil and vegetation. We demonstrate a new four-dimensional scale concept that includes not only spatial but also the spectral, directional and temporal components. Three scaling remote sensing techniques are reviewed: (1) radiative transfer, (2) spectral (un)mixing, and (3) data fusion. Relevant case studies are given in the context of their up- and/or down-scaling abilities over the soil/vegetation surfaces and a multi-source approach is proposed for their integration. Radiative transfer (RT) models are described to show their capacity for spatial, spectral up-scaling, and directional down-scaling within a heterogeneous environment. Spectral information and spectral derivatives, like vegetation indices (e.g. TCARI/OSAVI), can be scaled and even tested by their means. Radiative transfer of an experimental Norway spruce (Picea abies (L.) Karst.) research plot in the Czech Republic was simulated by the Discrete Anisotropic Radiative Transfer (DART) model to prove relevance of the correct object optical properties scaled up to image data at two different spatial resolutions. Interconnection of the successive modelling levels in vegetation is shown. A future development in measurement and simulation of the leaf directional spectral properties is discussed. We describe linear and/or non-linear spectral mixing techniques and unmixing methods that demonstrate spatial down-scaling. Relevance of proper selection or acquisition of the spectral endmembers using spectral libraries, field measurements, and pure pixels of the hyperspectral image is highlighted. An extensive list of advanced unmixing techniques, a particular example of unmixing a reflective optics system imaging spectrometer (ROSIS) image from Spain, and examples of other mixture applications give insight into the present status of scaling capabilities. Simultaneous spatial and temporal down-scaling by means of a data fusion technique is described. A demonstrative example is given for the moderate resolution imaging spectroradiometer (MODIS) and LANDSAT Thematic Mapper (TM) data from Brazil. Corresponding spectral bands of both sensors were fused via a pyramidal wavelet transform in Fourier space. New spectral and temporal information of the resultant image can be used for thematic classification or qualitative mapping. All three described scaling techniques can be integrated as the relevant methodological steps within a complex multi-source approach. We present this concept of combining numerous optical remote sensing data and methods to generate inputs for ecosystem process models.

Malenovský, Zbyn?k; Bartholomeus, Harm M.; Acerbi-Junior, Fausto W.; Schopfer, Jürg T.; Painter, Thomas H.; Epema, Gerrit F.; Bregt, Arnold K.

2007-05-01

78

Coupling the Soil-Vegetation-Atmosphere-Transfer Scheme ORCHIDEE to the agronomy model STICS to study the influence of croplands on the European carbon and water budgets  

Microsoft Academic Search

Agriculture is still accounted for in a very simplistic way in the land-surface models which are coupled to climate models, while the area it occupies will significantly increase in the next century according to future scenarios. In order to improve the representation of croplands in a Dynamic Global Vegetation Model named ORCHIDEE (which can be coupled to the IPSL1 climate

Nathalie de NOBLET-DUCOUDRÉa; Philippe Ciais; Nicolas Viovy; Nadine Brisson; Bernard Seguin; Alain Perrier

2004-01-01

79

On the dynamics of soil moisture, vegetation, and erosion: Implications of climate variability and change  

Microsoft Academic Search

We couple a shear-stress-dependent fluvial erosion and sediment transport rule with stochastic models of ecohydrological soil moisture and vegetation dynamics. Rainfall is simulated by the Poisson rectangular pulses rainfall model with three parameters: mean rainfall intensity, duration, and interstorm period. These parameters are related to mean annual precipitation on the basis of published data. The model is used to investigate

Erkan Istanbulluoglu; Rafael L. Bras

2006-01-01

80

Experimental verification of a mechanistic model of methane bubble formation in non-vegetated flooded rice field soil  

Microsoft Academic Search

Anoxic wetlands are an important source for the greenhouse gas CH4, much of which is emitted in form of gas bubbles. The conditions for formation of gas bubbles have recently been described by an analytical model, which allows the prediction of fluxes by first physical principles using the knowledge of gas concentration profiles and\\/or gas production rates. We verified parts

R. Conrad; A. Kusmin; N. M. Bazhin

2005-01-01

81

Vegetation and soil differences in ancient opposed to new forests  

Microsoft Academic Search

This study compared the vegetation and soils of forest stands with different land-use histories in a major forest complex with new forest stands isolated from ancient forests. Vegetation did not vary significantly in relation to former land-use within the major forest complex, but was significantly different between the major forest complex and the isolated new forests. Plant available phosphate, pH

B. J Graae; P. B Sunde; B Fritzbøger

2003-01-01

82

Modeling of the interactions between forest vegetation, disturbances, and sediment yields  

Microsoft Academic Search

The controls of forest vegetation, wildfires, and harvest vegetation disturbances on the frequency and magnitude of sediment delivery from a small watershed (?3.9 km2) in the Idaho batholith are investigated through numerical modeling. The model simulates soil development based on continuous bedrock weathering and the divergence of diffusive sediment transport on hillslopes. Soil removal is due to episodic gully erosion,

Erkan Istanbulluoglu; David G. Tarboton; Robert T. Pack; Charles H. Luce

2004-01-01

83

On the dynamics of soil moisture vegetation and erosion: Implications of stochastic climate forcing  

NASA Astrophysics Data System (ADS)

Landscapes are observable manifestations of dynamic interactions between climatic, hydrologic, geomorphic, and ecosystem processes. As such, understanding landscape system response to fluctuations and changes in climatic forcing is necessary to predict impacts of future climate change on landscapes, and interpret geological records as indicators of past climate. We develop a simple stochastic model for climate, soil moisture, vegetation and runoff erosion dynamics driven by the Poisson pulse rainfall model. In the model, runoff generation, moisture losses due to drainage and evapotranspiration, and vegetation growth and mortality are related to vegetation cover and soil moisture state. We apply this model to investigate the sensitivity of soil moisture, grass cover and erosion potential to rainfall variability (Rvar) and mean annual precipitation (MAP). In general, under fixed MAP and rainfall rate, both soil moisture and grass cover increase, reach a maximum, and then decrease as Rvar increases. Erosion potential tends to increase with reduced vegetation cover. Analysis of existing data suggests power-law dependence between both Rvar and interstorm period with MAP. When climate is characterized in this manner, the model shows both long-term mean soil moisture and vegetation cover increase with increasing MAP. Erosion potential, however, initially increases with increasing MAP, but reaches a peak and subsequently decreases as MAP grows large. Similar behavior between measured sediment yields and MAP have been reported in the literature for a range of climatic conditions. We find that the degree of nonlinear dependence between Rvar and MAP exerts an important control on the shape of the relationship between erosion potential and MAP. Results underscore the importance of coupled soil, vegetation and climate dynamics on erosion rates.

Istanbulluoglu, E.; Bras, R. L.; Flores, A. N.

2004-12-01

84

Antibiotic uptake by vegetable crops from manure-applied soils.  

PubMed

This study quantified the uptake of five antibiotics (chlortetracycline, monensin, sulfamethazine, tylosin, and virginiamycin) by 11 vegetable crops in two different soils that were fertilized with raw versus composted turkey and hog manures or inorganic fertilizer. Almost all vegetables showed some uptake of antibiotics from manure treatments. However, statistical testing showed that except for a few isolated treatments the concentrations of all antibiotics in vegetable tissues were generally less than the limits of quantification. Further testing of the significant treatments showed that antibiotic concentrations in vegetables from many of these treatments were not significantly different than the corresponding concentrations from the fertilizer treatment (matrix effect). All five antibiotic concentrations in the studied vegetables were <10 ?g kg(-1). On the basis of the standards for maximum residue levels in animal tissues and suggested maximum daily intake based on body weight, this concentration would not pose any health risk unless one is allergic to that particular antibiotic. PMID:24106840

Kang, Dong Hee; Gupta, Satish; Rosen, Carl; Fritz, Vincent; Singh, Ashok; Chander, Yogesh; Murray, Helene; Rohwer, Charlie

2013-10-09

85

Effect of Soil and Vegetation Heterogeneity on Runoff in a Semi-arid Grassland  

NASA Astrophysics Data System (ADS)

Vegetation in drylands is typically patchy, and surface soil properties tend to covary with this pattern. For example, infiltration rates tend to be relatively high under plant canopies, and decrease as a function of distance away from canopies. Vegetation also tends to exist on raised mounds of microtopography, and adjacent interspaces are topographically lower as a function of distance from vegetation patches. These patterns will clearly affect the locations where overland flow is generated and how it is routed on the landscape. Predicting soil erosion from overland flow therefore requires the ability to quantify how vegetation and soil properties covary over small-scales (i.e. decimeter to tens of meters). We use a two-dimensional numerical model that simulates overland flow using spatially variable vegetation, microtopography, and infiltration (saturated conductivity). We use a diffusion wave approximation for the shallow overland flow equations and green-ampt infiltration dynamics to simulate overland flow and infiltration at 5-cm grid cells. We calibrate unknown parameters such as roughness, and test the model with known spatial fields of surface properties and observed rainfall and runoff from eight ~100 m2 plots at the Sevilleta LTER in Central New Mexico. We interpolate measured surface properties with cokriging determined by geostatistical relationships to the vegetation pattern. We measure rainfall with tipping buckets and runoff at 5-second resolution from runoff gutters and flumes below the gently sloped grassland plots. Experiments indicate that bulk runoff volume is approximated as a function of surface depression volume and the mean and variance of microtopography and infiltration. We then simulate overland flow and erosion on plots that have experienced three years of vegetation reduction due to enforced drought in a controlled experiment. We quantify change in vegetation cover and pattern, and show how runoff discharge and patterns of overland flow and erosion are affected by this change in vegetation pattern, along with the covarying soil properties.

Bedford, D. R.; Small, E. E.; Tucker, G. E.; Pockman, W. T.

2006-12-01

86

Combined effect of soil erosion and climate change induces abrupt changes in soil and vegetation properties in semiarid Mediterranean shrublands.  

NASA Astrophysics Data System (ADS)

Semiarid Mediterranean ecosystems are experiencing major alterations as a result of the complex interactions between climatic fluctuations and disturbances caused by human activities. Future scenarios of global change forecast a rapid degradation of these ecosystems, with a reduction of their functionality, as a result of changes in relevant vegetation and soil properties. Some theoretical models indicate that these ecosystems respond non-linearly to regular variations in the external conditions, with an abrupt shift when conditions approach a certain critical level or threshold. Considering these predictions, there is an urgent need to know the effects that these alterations might have on semi-arid ecosystems and their components. In this study, we aim at analyzing the consequences of climate change and increasing soil erosion on soil and vegetation properties and the functional dynamics of semiarid Mediterranean shrublands. We predict that the combined effect of both drivers will be additive or synergistic, increasing the negative effects of each one. We compared vegetation and soil properties of flat areas (low erosion) and steep hillslopes (high erosion) in two climatic areas (484 mm and 10.3°C, and 368mm and 11.9°C, respectively) that reproduce the predicted climate change in temperature and precipitation for the next 40 years. Species richness, vegetal cover, plant life-form composition were determined in 20 m2 plots and soil was sampled in the same plots to determine bulk density, aggregate stability, fertility and water holding capacity. All soil and vegetation properties were negatively affected by soil erosion and climate change. However, contrary to our hypothesis, the joined effect of both drivers on all soil and vegetation properties was antagonistic, except for the vegetal cover that showed an additive response to their interaction. Our results evidence that soil erosion affects more negatively the soil and vegetation properties in the cooler and wetter climatic area than in the warmer and drier one, and support moreover the idea that a functional threshold has been crossed between the two climatic areas.

Bochet, Esther; García-Fayos, Patricio

2013-04-01

87

Physics-based colour image segmentation for scenes containing vegetation and soil  

Microsoft Academic Search

Colour segmentation of images containing vegetation and soil is the theme of this work. Physics-based reflection models are used to develop an algorithm for separating object pixel clusters in the three-dimensional red, green and blue colour space. The dichromatic reflection model that is used as the basis for this algorithm, defines a plane in which the pixels from an object

Christine M. Onyango; John A. Marchant

2001-01-01

88

Soil moisture and vegetation memories in a cold, arid climate  

NASA Astrophysics Data System (ADS)

Continental climate is established as a result of a complex interplay between the atmosphere and various land-surface systems such as the biosphere, soil, hydrosphere, and cryosphere. These systems function as climate memory, allowing the maintenance of interannual atmospheric anomalies. In this paper, we present new observational evidence of an interseasonal moisture memory mechanism mediated by the land surface that is manifested in the coupled cold and arid climate of Mongolia. Interannual anomalies of soil moisture and vegetation due to rainfall during a given summer are maintained through the freezing winter months to the spring, acting as an initial condition for subsequent summer land-surface and rainfall conditions. Both the soil moisture and vegetation memories were prominent over the eastern part of the Mongolian steppe zone (103-112°E and 46-50°N). That is, the cold-season climate with low evapotranspiration and strong soil freezing acts to prolong the decay time scale of autumn soil moisture anomalies to 8.2 months that is among the longest in the world. The vegetation also has a memory of the similar time scale, likely because the large rootstock of the perennial plants dominant in the Mongolian steppe may remain alive, retain belowground biomass anomalies during the winter, and have an impact on the initial vegetation growth during the spring.

Shinoda, Masato; Nandintsetseg, Banzragch

2011-10-01

89

Impacts of vegetation and cold season processes on soil moisture and climate relationships over Eurasia  

NASA Astrophysics Data System (ADS)

A number of modeling studies have addressed soil moisture persistence and its effects on the atmosphere. Such analyses are particularly valuable for seasonal to interannual prediction. In this study, we perform an observation-based study to further investigate the impacts of vegetation and cold season processes on soil moisture persistence and climate feedbacks. The joint analysis of independent meteorological, soil moisture and land cover measurements, without the use of a model, in the former Soviet Union provides a unique look at soil moisture-climate relationships at seasonal to interannual timescales. Averaged data over the growing season show a strong consistency between soil moisture and precipitation over grassland dominant regions, suggesting that precipitation anomalies are a dominant control of soil moisture at interannual timescales. Investigation of soil moisture persistence at the seasonal timescale shows a strong correlation between soil moisture in spring and the subsequent precipitation in summer over forest dominant regions and between cold season precipitation accumulation in winter and soil moisture in the following spring. Our findings can be explained by the theory proposed by Koster and Suarez (2001) and are consistent with the results from other modeling studies. Although it is hard to obtain the statistical meaningful conclusions because of the short data records, our results show the potential role of vegetation and cold season processes in land-atmosphere interactions. Further modeling studies and analyses using long in situ data records are necessary to fully verify our results.

Dong, Jiarui; Ni-Meister, Wenge; Houser, Paul R.

2007-05-01

90

Uptake of 137Cs by Leafy Vegetables and Grains from Calcareous Soils  

SciTech Connect

Cesium-137 was deposited on Bikini Island at Bikini Atoll in 1954 as a result of nuclear testing and has been transported and cycled in the ecosystem ever since. Atoll soils are of marine origin and are almost pure CaCO{sub 3} with high concentrations of organic matter in the top 40 cm. Data from previous experiments with mature fruit trees show very high transfer factors (TF's), [Bq g{sup -1} plant/ Bq g{sup -1} soil, both in dry weight] into fruits from atoll calcareous soil. These TF's are much higher than reported for continental, silica-based soils. In this report TF's for 5 types of leafy vegetable crops and 2 types of grain crops are provided for use in predictive dose assessments and for comparison with other data from other investigators working with other types of soil in the IAEA CRP ''The Classification of Soil Systems on the Basis of Transfer Factors of Radionuclides from Soil to Reference Plants''. Transfer factors for plants grown on calcareous soil are again very high relative to clay-containing soils and range from 23 to 39 for grain crops and 21 to 113 for leafy vegetables. Results from these experiments, in this unique, high pH, high organic content, low potassium (K) soil, provide a boundary condition for models relating soil properties to TF.

Robison, W; Hamilton, T; Conrado, C; Kehl, S

2004-04-19

91

Soil Moisture and Vegetation Effects on GPS Reflectivity From Land  

NASA Astrophysics Data System (ADS)

While originally designed as a navigation system, the GPS signal has been used to achieve a number of useful scientific measurements. One of these measurements utilizes the reflection of the GPS signal from land to determine soil moisture. The study of GPS reflections is based on a bistatic configuration that utilizes forward reflection from the surface. The strength of the GPS signal varies in proportion to surface parameters such as soil moisture, soil type, vegetation cover, and topography. This paper focuses on the effects of soil water content and vegetation cover on the surface based around a reflectivity. A two-part method for calibrating the GPS reflectivity was developed that permits the comparison of the data with surface parameters. The first part of the method relieves the direct signal from any multipath effects, the second part is an over-water calibration that yields a reflectivity independent of the transmitting satellite. The sensitivity of the GPS signal to water in the soil is shown by presenting the increase in reflectivity after rain as compared to before rain. The effect of vegetation on the reflected signal is also presented by the inclusion of leaf area index as a fading parameter in the reflected signal from corn and soy bean fields. The results are compared to extensive surface measurements made as part of the Soil Moisture Experiment 2002 (SMEX 2002) in Iowa and SMEX 2003 in Georgia.

Torres, O.; Grant, M. S.; Bosch, D.

2004-12-01

92

Vegetation on the Soil Infiltration System Treating Livestock Wastewater  

NASA Astrophysics Data System (ADS)

In the overland flow wastewater treatments and the constructed wetlands, the purification by soil infiltration units is enhanced using vegetation. However, wetland plants (i.e. cattail (Typha latifolia)) and trees, rather than agronomic crops, have been used in conventional systems. We carried out laboratory-scale soil infiltration experiments using two forage crops, tall fescue (Festuca araundinacea) and white clover (Trifolium repens) while using livestock wastewater for irrigation. The purpose of the study was to clarify the amount of accumulation of available phosphorus and exchangeable cations in the soil and its effect on the plant growth. The application of livestock wastewater increased available phosphorus, and exchangeable potassium and sodium in the upper soil. The soil sodification, examined based on exchangeable sodium ratio and plant growth, was not very significant after 10 months of livestock wastewater application. Growing forage crops on the soil infiltration system may be a promising technology to improve crop production and treatment efficacy.

Sakurai, Shinji; Fujikawa, Yoko; Fukui, Masami; Hamasaki, Tastuhide; Sugahara, Masataka

93

Error assessment in decision-tree models applied to vegetation analysis  

Microsoft Academic Search

Methods were developed to evaluate the performance of a decision-tree model used to predict landscape-level patterns of potential forest vegetation in central New York State. The model integrated environmental databases and knowledge on distribution of vegetation. Soil and terrain decision-tree variables were derived by processing state-wide soil geographic databases and digital terrain data. Variables used as model inputs were soil

Henry Lynn; Charles L. Mohler; Stephen D. DeGloria; Charles E. McCulloch

1995-01-01

94

Modeling the interaction between plant canopies and the planetary boundary layer using a new 1D multi-layer soil- vegetation-atmosphere transfer (SVAT) scheme combined with a non-local turbulence closure model  

NASA Astrophysics Data System (ADS)

A new one-dimensional (1D) soil-vegetation-atmospheric transport (SVAT) scheme is coupled to a nonlocal turbulence closure model in order to simulate the interactions between a forested canopy and the planetary boundary layer. The SVAT consists of mechanistic models for both physiological (photosynthesis, stomatal conductance and soil/root and bole respiration) and micrometeorological (radiative transfer and surface energy exchanges) processes. The turbulence closure model is a first-order, nonlocal turbulence closure called transilient turbulence theory (Stull, 1993; Inclan et al., 1995) which includes the effects of form drag, wake turbulence, and interference to vertical mixing by the plant elements. The submodel that accounts for radiative transfer inside the forest has been taken from Norman (1979) and Baldocchi (1989). It includes the effect of varying mean leaf inclination angle with height and it also accounts for leaf clumping The photosynthesis submodel is taken from Nikolov and others (1995). It accounts for both differences between shaded and sunlit leaves and the variation of photosynthetic capacity with height. The model was tested with data obtained from a deciduous forest in Pennsylvania. The results show reasonable agreement with the observations. They also demonstrate the model's ability to simulate phenomena that is characteristic of tall canopies like forests, including counter gradient-fluxes and local wind speed maxima in the trunk space.

Yetzer, Kenneth H.

95

Aminopyralid soil residues affect rotational vegetable crops in Florida  

Technology Transfer Automated Retrieval System (TEKTRAN)

Field experiments were conducted to determine the sensitivity of bell pepper, eggplant, tomato, muskmelon, and watermelon to aminopyralid soil residues. Aminopyralid was applied at six rates ranging from 0.0014 kg ae ha 1 to 0.0448 kg ae ha 1, and vegetable crops were planted in the treated areas. ...

96

Derivation of a global soil moisture and vegetation database from passive microwave signals  

NASA Astrophysics Data System (ADS)

A series of validation studies for a recently developed soil moisture retrieval algorithm is presented. The approach is largely theoretical, and uses a non-linear iterative optimisation procedure to solve for soil moisture and vegetation optical depth with a radiative transfer model from satellite microwave observations. The new theoretical approach is not dependent on field observations of soil moisture or canopy biophysical measurements and can be used at any wavelength in the microwave region. Details of the model and its development are discussed. Satellite retrievals were derived from 6.6 GHz Nimbus/SMMR brightness temperatures, and were validated with soil moisture data sets from the U.S., Mongolia, and Turkmenistan. Time series of the satellite-derived surface moisture compared well with the available ground observations and precipitation data. The vegetation optical depth showed similar seasonal patterns as the NDVI.

De Jeu, Richard A. M.; Owe, Manfred

2003-03-01

97

[Investigation of polarization characteristics of soil surface with low vegetation cover and different soil moisture].  

PubMed

Compared with the spectral detection method, polarization detection could obtain more information of the target. For example, the polarization detection could be applied to interpret the refractive index and the surface roughness of the object, or retrieve the soil moisture, etc. Polarization detection provides a new approach to quantitative retrieval of soil moisture, and this is very important in agriculture, hydrology, meteorology and ecology. The polarization characteristics of soil surface with low vegetation cover,which is a example of mixed pixel in remote sensing, were researched with experiments, and the relationship between the polarization characteristics and soil moisture was also explored. The results showed that the polarization characteristics of soil surface with low vegetation cover are mainly determined by the area of bare soil, and are strongly relevant with the soil moisture. For the results of experiments in this paper, the IDOLP of soil surface with low vegetation cover increased with increasing soil moisture when the viewing angle of instrument was between 20 degree and 60 degree, while the incident angle of light source was fixed at 40 degree. This paper offered a new method to retrieve moisture content of soil with low vegetation cover. PMID:21284189

Zhang, Qiao; Sun, Xiao-bing; Hong, Jin

2010-11-01

98

Infiltration and Transport of Bromide and Cryptosporidium parvum in Vegetated, Tilted Soil Box Experiments  

NASA Astrophysics Data System (ADS)

In this paper we develop a conceptual model of the physics of flow and transport in packed, tilted, and vegetated soil boxes during and immediately after simulated rainfall events and apply it to 54 experiments implemented for three different soils at three different slopes and two different rainfall rates. Using an inverse modeling procedure, we show that a significant amount of the subsurface outflow from the soil boxes is due to macropore flow. The effective hydraulic properties of the macropore space were obtained by calibration of a simple two-domain flow and transport model that accounts for coupled flow in the matrix and in the macropores of the soils. While the macropore hydraulic properties are highly variable, linear mixed effects ( LME) modeling showed significant association with soil bulk density and with the rainfall rate. Macropore flow is shown to be responsible for both, tracer (bromide) and C. parvum transport through the soil into the underlying pore space observed during the 4 hours experiments. Over a 20 cm thick soil horizon, the soil attenuation rate for C. parvum due to straining in the soil matrix and due to filtration to the macropore surfaces is 0.6 (half an order of magnitude). The LME and logistic regression models developed from the soil box experiments provide a basis for estimating macropore hydraulic properties and the risk of C. parvum transport through shallow soils from bulk density, precipitation, and total subsurface flow rate information.

Harter, T.; Atwill, E. R.; Hou, L.; Carle, B. M.

2005-12-01

99

Spatial variability of soils in vegetation zone of Fukang oasis  

NASA Astrophysics Data System (ADS)

Soil samples collected from vegetation zone of Fukang oasis in South Junggar Basin were analyzed. The soil samples were air-dried and their PH values, electrical conductivity and total salts were analyzed in the laboratory. Soil samples were weighted and mixed with distilled water by a ratio of 1:5 after stirred and settled over night. Moisture content of soil was measured by the dry-method, PH value was measured by SM-10 digital acidity-meter, and electrical conductivity was measured by weight-method. The PH value, electrical conductivity and total salts of soil were measured from 0-10cm, 10-30cm and 30-50cm vertically. The study uses SAS software to analyze the statistical characteristic of the moisture content, electrical conductivity and total salts of the soil samples. The results show that soil properties are inhomogeneous. From the surface to below 50cm, moisture content and electrical conductivity increase successively, the change of PH value is not significant. The soil is alkalescence. In most circumstances, the data of moisture content, PH value and electrical conductivity are normally distributed. But, in the procession, soil properties influenced by systematic variance of soil properties deviated for normal distribution with various degrees. Soil moisture content, PH value and electrical conductivity do not satisfy simple linear relation at the vegetation zone of Fukang oasis. Using the method of trend surface analysis, the polynomial relation of variances (P<0.01) was obtained and found that moisture content is higher related with electrical conductivity at different depths, but the correlation between moisture content and PH value, and the correlation between PH value and electrical conductivity change with different environment factors.

Lv, Guanghui; Shi, Qingdong; Pan, Xiaoling; Li, Weiqing; Zhan, Xiwu; Chang, Shunli

2004-01-01

100

Wetland Soils and Vegetation, Arctic Foothills, Alaska.  

National Technical Information Service (NTIS)

Analyses of relationships between hydric soils and wetland plant species were made at a 22 cu km site in the northern foothills of the Brooks Range, Alaska, as part of a cooperative effort between the FWS and SCS to develop methods for field identificatio...

M. D. Walker D. A. Walker K. R. Everett

1989-01-01

101

Wetland Soils and Vegetation, Arctic Foothills, Alaska.  

National Technical Information Service (NTIS)

This report is one of a series sponsored by the FWS to examine relationships between wetland plants and soils in a variety of habitats. It examines a first order watershed in the Arctic Foothills of the Brooks Range, northern Alaska, which is representati...

M. D. Walker D. A. Walker K. R. Everett

1989-01-01

102

Modeling E. Coli Retention in Vegetated Filter Strips  

Technology Transfer Automated Retrieval System (TEKTRAN)

Vegetated filter strips (VFS) have become important for water quality improvement. Locations to place VFS can be selected with Soil & Water Assessment Tool (SWAT), a comprehensive watershed-scale water quality model. However, the VFS efficiency cannot be estimated with SWAT because the VFS factors, ...

103

Sulfamethazine Sorption to Soil: Vegetative Management, pH, and Dissolved Organic Matter Effects.  

PubMed

Elucidating veterinary antibiotic interactions with soil is important for assessing and mitigating possible environmental hazards. The objectives of this study were to investigate the effects of vegetative management, soil properties, and >1000 Da dissolved organic matter (DOM) on sulfamethazine (SMZ) behavior in soil. Sorption experiments were performed over a range of SMZ concentrations (2.5-50 ?mol L) using samples from three soils (Armstrong, Huntington, and Menfro), each planted to one of three vegetation treatments: agroforestry buffers strips (ABS), grass buffer strips (GBS), and row crops (RC). Our results show that SMZ sorption isotherms are well fitted by the Freundlich isotherm model (log = 0.44-0.93; Freundlich nonlinearity parameter = 0.59-0.79). Further investigation of solid-to-solution distribution coefficients () demonstrated that vegetative management significantly ( < 0.05) influences SMZ sorption (ABS > GBS > RC). Multiple linear regression analyses indicated that organic carbon (OC) content, pH, and initial SMZ concentration were important properties controlling SMZ sorption. Study of the two most contrasting soils in our sample set revealed that increasing solution pH (pH 6.0-7.5) reduced SMZ sorption to the Armstrong GBS soil, but little pH effect was observed for the Huntington GBS soil containing 50% kaolinite in the clay fraction. The presence of DOM (150 mg L OC) had little significant effect on the Freundlich nonlinearity parameter; however, DOM slightly reduced SMZ values overall. Our results support the use of vegetative buffers to mitigate veterinary antibiotic loss from agroecosystems, provide guidance for properly managing vegetative buffer strips to increase SMZ sorption, and enhance understanding of SMZ sorption to soil. PMID:23673946

Chu, Bei; Goyne, Keith W; Anderson, Stephen H; Lin, Chung-Ho; Lerch, Robert N

104

Transfer of metals from soil to vegetables in an area near a smelter in Nanning, China  

Microsoft Academic Search

A field survey was conducted to investigate the metal contamination in soils and vegetables, and to evaluate the possible health risks to local population through foodchain transfer near a smelter in Nanning, southern China. Contamination levels in soils and vegetables with cadmium (Cd), lead (Pb), zinc (Zn) and copper (Cu) were measured, and transfer factors (TF) from soils to vegetable

Yu-Jing Cui; Yong-Guan Zhu; Ri-Hong Zhai; Deng-Yun Chen; Yi-Zhong Huang; Yi Qiu; Jian-Zhong Liang

2004-01-01

105

Relationship Between Vegetation Restoration and Soil Microbial Characteristics in Degraded Karst Regions: A Case Study  

Microsoft Academic Search

The mechanism of vegetation restoration on degraded karst regions has been a research focus of soil science and ecology for the last decade. In an attempt to preferably interpret the soil microbiological characteristic variation associated with vegetation restoration and further to explore the role of soil microbiology in vegetation restoration mechanism of degraded karst regions, we measured microbial biomass C

Yuan WEI; Li-Fei YU; Jin-Chi ZHANG; Yuan-Chun YU; D. L. DEANGELIS

2011-01-01

106

Soil moisture and vegetation controls on evapotranspiration in a heterogeneous Mediterranean ecosystem on Sardinia, Italy  

NASA Astrophysics Data System (ADS)

Micrometeorological measurements of evapotranspiration (ET) can be difficult to interpret and use for validating model calculations in the presence of land cover heterogeneity. Land surface fluxes, soil moisture (?), and surface temperatures (Ts) data were collected by an eddy correlation-based tower located at the Orroli (Sardinia) experimental field (covered by woody vegetation, grass, and bare soil) from April 2003 to July 2004. Two Quickbird high-resolution images (summer 2003 and spring 2004) were acquired for depicting the contrasting land cover components. A procedure is presented for estimating ET in heterogeneous ecosystems as the residual term of the energy balance using Ts observations, a two-dimensional footprint model, and the Quickbird images. Two variations on the procedure are successfully implemented: a proposed two-source random model (2SR), which treats the heat sources of each land cover component separately but computes the bulk heat transfer coefficient as spatially homogeneous, and a common two-source tile model. For 2SR, new relationships between the interfacial transfer coefficient and the roughness Reynolds number are estimated for the two bare soil-woody vegetation and grass-woody vegetation composite surfaces. The ET versus ? relationships for each land cover component were also estimated, showing that that the woody vegetation has a strong tolerance to long droughts, transpiring at rates close to potential for even the driest conditions. Instead, the grass is much less tolerant to ? deficits, and the switch from grass to bare soil following the rainy season had a significant impact on ET.

Detto, Matteo; Montaldo, Nicola; Albertson, John D.; Mancini, Marco; Katul, Gaby

2006-08-01

107

Ecohydrological feedbacks between soil salinity and vegetation dynamics as mediated by interactions with the water table  

NASA Astrophysics Data System (ADS)

In areas with relatively shallow water tables, changes in vegetation cover may affect local hydrologic conditions and favor the accumulation of salt within different parts of the soil profile. Because most plants are sensitive to saline soil water, a salt-vegetation feedback may exist, whereby vegetation cover maintains deeper water tables and slower rates of salt accumulation. As a result of this feedback, both a state with vegetation cover, deep water table, and low salinity, and a state with sparse or no vegetation, shallow water table and high salinity can be stable. Such dynamics may be present in the Murray Darling Basin, Australia, where widespread conversion from sclerophyll woodlands and forests to agricultural use has resulted in a decrease in the water table depth that has mobilized salts accumulated in the vadose zone and strongly increased the rate at which salts are transported within the system. To investigate these dynamics, we present a model to relate vegetation-soil salinity feedbacks - mediated by hydrologic conditions - to the emergence of multiple stable states in the underlying dynamics and apply this model to the Murray Darling Basin. Results for this case study show the presence of a strong feedback resulting in bistable dynamics for a wide range of environmental conditions (i.e., a range of precipitation regimes, soil textures, and salinities of irrigation and groundwater). This bistability increases the susceptibility of these systems to abrupt, highly irreversible shifts to stable bare soil, saline conditions and has important economic implications for dryland agricultural regimes worldwide as the presence of a shallow, saline water table is known to require costly remediation measures.

Runyan, C.; D'Odorico, P.

2010-12-01

108

The Role of Vegetation Dynamics on the Soil Water Balance in Water-Limited Ecosystems  

NASA Astrophysics Data System (ADS)

The structure and function of the vegetation regulates the exchange of mass, energy and momentum across the biosphere-atmosphere interface. Vegetation dynamics are usually neglected, other than seasonal phenology, in land surface models (LSMs). However, changes in vegetation densities, influencing the partitioning of incoming solar energy into sensible and latent heat fluxes, can result in long-term changes in both local and global climates (e.g., precipitation and temperature), which in turn will feedback to affect the vegetation growth. In semi-arid regions, this may result in persistent drought and desertification, with substantial impacts on the human populations of these regions through reduction in agricultural productivity and reduction in quantity and quality of water supply. With an objective of finding a simple vegetation model able to accurately simulate the leaf area index (LAI) dynamics, vegetation models of different level of complexity (e.g., including or not the modeling of the root biomass or the modeling of the dead biomass) are developed and compared. The vegetation dynamics models are coupled to a LSM, with the vegetation models providing the green biomass and the LAI evolution through time, and the LSM using this information in the computation of the land surface fluxes and updating the soil water content in the root-zone. We explore the models on a case study of a water limited grass field in California. Results show that a simple vegetation model that simulates the living aboveground green biomass (i.e., with low parameterization and computational efforts) is able to accurately simulate the LAI. Results also highlight the importance of including the plant growth model in the LSM when studying the climate-soil-vegetation interactions and the impact of watershed management practices on the scarce water resources over moderate to long time scales. The inclusion of the vegetation model in the LSM is demonstrated to be essential for assessing the impact of climate change (e.g., decrease of precipitation and increase of air temperature) on the water budget of a water limited region.

Montaldo, N.; Rondena, R.; Albertson, J. D.; Mancini, M.

2003-12-01

109

Modelling the Effects of Vegetation on Stability of Slopes  

Microsoft Academic Search

Summary: It is well understood that vegetation influences slope stability in two ways: through hydrological effects and mechanical effects. Hydrological effects involve the removal of soil water by evapotranspiration through vegetation, which lead to an increase in soil suction or a reduction in pore-water pressure, hence, an increase in the soil shear strength. The shear strength of the soil is

Y H Chok; M. I. E. Aust; M B Jaksa; D V Griffiths

110

Vegetation loss alters soil nitrogen dynamics in an Arctic salt marsh  

Microsoft Academic Search

Summary 1 Plant and microbial nitrogen (N) dynamics were examined in soils of an Arctic salt marsh beneath goose-grazed swards and in degraded soils. The degraded soils are the outcome of intensive destructive foraging by geese, which results in vegetation loss and near-irreversible changes in soil properties. The objective of the study was to determine whether vegetation loss led to

KATE M. BUCKERIDGE; ROBERT L. JEFFERIES

2007-01-01

111

A comparison of soil properties under four vegetation units from six metalliferous hills in Katanga  

NASA Astrophysics Data System (ADS)

In Katanga (Democratic Republic of Congo), numerous metalliferous hills are distributed along what is called the copperhill belt from Kolwezi to Lubumbashi. Very specific vegetation developed on these hills within the miombo forest in response to very specific soil conditions, among which the copper content. Previous studies have already shown the existence of gradients of copper from the mineralized rocks outcropping at the top of the hills to the foot slopes on colluviums. After a characterization of the vertical variability of soil properties in pits distributed along the main slopes, we investigated the soil-vegetation relationships in six hills located between the towns of Tenke and Fungurume. Observation 1-square meter plots were installed in four vegetation units and sixty of them were selected according to their relative importance on the six hills. The soil from the top 10cm was sampled and analyzed for pH, Total Organic Carbon, available P, K, Mg, Ca, Cu, Co and Mn and soluble Cu and Co. Analysis of variance was performed in order to assess whether the effects of the "Hill" and of the "Vegetation Unit" were significant to explain soil chemical variability. Additionally, short transects were sampled at the boundaries from adjacent vegetation units in order to evaluate the gradual or rough nature of change in soil properties under these units. The results indicate that the six hills can not be considered as different for pH and available nutrients, excepted K, nor for the available Cu and Mn. Only TOC and Co contents were differing, mainly from one hill compared to the other five. The vegetation effect is significant for almost every studied soil characteristics, to the exception of Ca and Mn. Soluble Cu and Co significantly correlate to available Cu and Co, respectively. The pH variations however explain local departures from linear regression. The ANOVA models take into account 30 to 60% of the variations of soil properties. The study of the boundaries indicate that most changes of vegetation types may be related to abrupt changes in soil properties. These changes do not only occur along the slope as a result of malachite deposition by erosion but the surface processes seem to be predominant in the context of the hills.

Kaya, Donato; Gregory, Mahy; Michel, Ngongo; Gilles, Colinet

2013-04-01

112

Soil phosphorus forms as quality indicators of soils under different vegetation covers.  

PubMed

The type of vegetation cover determines the physicochemical and biological properties of the soil over which they are developing. The objective of this study was to determine the effect of different vegetation covers on the forms of soil phosphorus, in order to know which of these forms can be used as a soil quality indicator. The experimental area was located on the acidic plateau at the North of Palencia (North Spain), where an area was selected vegetation covers very close to each other: pine (Pinus sylvestris), oak (Quercus pyrenaica), and three different shrub species (Arctostaphylos uva-ursi, Erica australis and Halimium alyssoides). The Ah horizon was sampled and pH, total organic C (C(org)), total N (N), cationic exchange capacity (CEC), sum of bases (S) and P forms by a sequential fractionation were analysed. Results showed that oak and A. uva-ursi improve the considered soil parameters (pH, C(org)/N ratio, CEC, and S) and provide soils of better quality. Inorganic soil P forms were influenced in greater extent by the vegetation cover than were P organic forms. Labile inorganic P forms could be used as indicators of soil quality. The organic P forms were less sensitive than inorganic ones to the indicated improvements. PMID:17307240

Turrión, María-Belén; López, Olga; Lafuente, Francisco; Mulas, Rafael; Ruipérez, César; Puyo, Alberto

2007-02-20

113

Fungal communities in soils along a vegetative ecotone.  

PubMed

We investigated the community composition and diversity of soil fungi along a sharp vegetative ecotone between coastal sage scrub (CSS) and nonnative annual grassland habitat at two sites in coastal California. USA- We pooled soil samples across 29 m transects on either side of the ecotone at each of the two sites, and. using clone libraries of fungal ribosomal DNA, we identified 280 operational taxonomic units (OTUs) from a total 40 g soil. We combined information from partial LSU and ITS sequences and found that the majority of OTUs belonged to the phylum Ascomycota, followed by Basidiomycota. Within the Ascomycota. a quarter of OTUs were Sordariomycetes. 17% were Leotiomycet.es, 16% were Dothideomycetes and the remaining OTUs were distributed among the classes Eurotiomycetes, Pezizomycetes, Lecanoromycetes, Orbiliomycetes and Arthoniomycetes. Within the Basidiomycota. all OTUs but one belonged to the subphylum Agaricomycotina. We also sampled plant communities at the same sites to offer a point of comparison for patterns in richness of fungal communities. Fungal communities had higher alpha and beta diversity than plant communities; fungal communities were approximately 20 times as rich as plant communities and the majority of OTUs were found in single soil samples. Soils harbored a unique mycoflora that did not reveal vegetative boundaries or site differences. High alpha and beta diversity and possible sampling artifacts necessitate extensive sampling to reveal differentiation in these fungal communities. PMID:22802393

Karst, Justine; Piculell, Bridget; Brigham, Christy; Booth, Michael; Hoeksema, Jason D

2012-07-16

114

Evidence of soil moisture control of energy partitioning with vegetation  

NASA Astrophysics Data System (ADS)

The seminal works by Dooge, Linear Theory of Hydrologic Systems, and Eagleson, Dynamic Hydrology, have shaped and guided hydrologists, and hydrology, over the past 30 years. Both Dooge and Eagleson were interested in the controlling mechanisms of hydrologic processes, including evapotranspiration. Their investigations into the switching mechanisms for control of soil evaporation and persistence and feedback in partitioning of latent and sensible heat fluxes as a function of soil moisture conditions have been leading contributions in these areas of study. Long-term, 20-min frequency data from the Oregon Evapotranspiration Investigation Plot (ETIP) from spring, summer and fall periods, including a special summer dry-down experiment, are analyzed for impacts of soil moisture content on daily Bowen ratio and daily ratio of measured grass evapotranspiration to a Penman-Monteith reference evapotranspiration. The gradual shift in partitioning of available energy between latent and sensible heat fluxes within a growing vegetative canopy with fully developed root zone illustrates the complexity of the processes and the difficulty of determining control processes compared to bare soil conditions with no vegetation. A full suite of data for radiation balance, soil parameters and moisture content, latent and sensible heat fluxes and micrometeorological parameters over a 125-day period in 1992 are exploited. Encompassed within these data is a special 30-day summer dry-down experiment.

Cuenca, R. H.; O Kane, J. P.

2003-04-01

115

Evaluating the dependence of vegetation on climate in an improved dynamic global vegetation model  

NASA Astrophysics Data System (ADS)

The capability of an improved Dynamic Global Vegetation Model (DGVM) in reproducing the impact of climate on the terrestrial ecosystem is evaluated. The new model incorporates the Community Land Model-DGVM (CLM3.0-DGVM) with a submodel for temperate and boreal shrubs, as well as other revisions such as the “two-leaf” scheme for photosynthesis and the definition of fractional coverage of plant functional types (PFTs). Results show that the revised model may correctly reproduce the global distribution of temperate and boreal shrubs, and improves the model performance with more realistic distribution of different vegetation types. The revised model also correctly reproduces the zonal distributions of vegetation types. In reproducing the dependence of the vegetation distribution on climate conditions, the model shows that the dominant regions for trees, grasses, shrubs, and bare soil are clearly separated by a climate index derived from mean annual precipitation and temperature, in good agreement with the CLM4 surface data. The dominant plant functional type mapping to a two dimensional parameter space of mean annual temperature and precipitation also qualitatively agrees with the results from observations and theoretical ecology studies.

Zeng, Xiaodong

2010-09-01

116

Environmental sensor networks for vegetation, animal and soil sciences  

NASA Astrophysics Data System (ADS)

Environmental sensor networks (ESNs) provide new opportunities for improving our understanding of the environment. In contrast to remote sensing technologies where measurements are made from large distances (e.g. satellite imagery, aerial photography, airborne radiometric surveys), ESNs focus on measurements that are made in close proximity to the target environmental phenomenon. Sensors can be used to collect a much larger number of measurements, which are quantitative and repeatable. They can also be deployed in locations that may otherwise be difficult to visit regularly. Sensors that are commonly used in the environmental sciences include ground-based multispectral vegetation sensors, soil moisture sensors, GPS tracking and bioacoustics for tracking movement in wild and domesticated animals. Sensors may also be coupled with wireless networks to more effectively capture, synthesise and transmit data to decision-makers. The climate and weather monitoring domains provide useful examples of how ESNs can provide real-time monitoring of environmental change (e.g. temperature, rainfall, sea-surface temperature) to many users. The objective of this review is to examine state-of-the-art use of ESNs for three environmental monitoring domains: (a) terrestrial vegetation, (b) animal movement and diversity, and (c) soil. Climate and aquatic monitoring sensor applications are so extensive that they are beyond the scope of this review. In each of the three application domains (vegetation, animals and soils) we review the technologies, the attributes that they sense and briefly examine the technical limitations. We conclude with a discussion of future directions.

Zerger, A.; Viscarra Rossel, R. A.; Swain, D. L.; Wark, T.; Handcock, R. N.; Doerr, V. A. J.; Bishop-Hurley, G. J.; Doerr, E. D.; Gibbons, P. G.; Lobsey, C.

2010-10-01

117

Vegetation Transformation, Functional Compensation, and Soil Health in a Semi-Arid Environment  

Microsoft Academic Search

Earthworm densities, mesofaunal and microbiological feeding activity, and soil moisture were measured as indicators of soil health. Fence line contrast sites were used to compare soil organism communities, infiltration rates and soil temperatures of natural vegetation remnants with adjacent transformed lands. Natural remnants retain soil moisture and contain more active soil fauna. Effects of land transformation are demonstrated by a

Patrick J. OFarrell; John S. Donaldson; M. Timm Hoffman

2010-01-01

118

Influence of vegetation on low-molecular-weight carboxylic acids in soil solution—a review  

Microsoft Academic Search

Low-molecular-weight (LMW) carboxylic acids found in soils and soil solutions comprise mainly aliphatic mono-, di- and tricarboxylic acids and substituted benzoic and cinnamic acids. This review compiles current information on the content of LMW carboxylic acids in soil solutions collected by centrifugation and in lysimeters, and soil extracts in relation to type of vegetation, soil type and soil depth. Contents

Bjarne W Strobel

2001-01-01

119

Soil TPH concentration estimation using vegetation indices in an oil polluted area of eastern China.  

PubMed

Assessing oil pollution using traditional field-based methods over large areas is difficult and expensive. Remote sensing technologies with good spatial and temporal coverage might provide an alternative for monitoring oil pollution by recording the spectral signals of plants growing in polluted soils. Total petroleum hydrocarbon concentrations of soils and the hyperspectral canopy reflectance were measured in wetlands dominated by reeds (Phragmites australis) around oil wells that have been producing oil for approximately 10 years in the Yellow River Delta, eastern China to evaluate the potential of vegetation indices and red edge parameters to estimate soil oil pollution. The detrimental effect of oil pollution on reed communities was confirmed by the evidence that the aboveground biomass decreased from 1076.5 g m(-2) to 5.3 g m(-2) with increasing total petroleum hydrocarbon concentrations ranging from 9.45 mg kg(-1) to 652 mg kg(-1). The modified chlorophyll absorption ratio index (MCARI) best estimated soil TPH concentration among 20 vegetation indices. The linear model involving MCARI had the highest coefficient of determination (R(2)?=?0.73) and accuracy of prediction (RMSE?=?104.2 mg kg(-1)). For other vegetation indices and red edge parameters, the R(2) and RMSE values ranged from 0.64 to 0.71 and from 120.2 mg kg(-1) to 106.8 mg kg(-1) respectively. The traditional broadband normalized difference vegetation index (NDVI), one of the broadband multispectral vegetation indices (BMVIs), produced a prediction (R(2)?=?0.70 and RMSE?=?110.1 mg kg(-1)) similar to that of MCARI. These results corroborated the potential of remote sensing for assessing soil oil pollution in large areas. Traditional BMVIs are still of great value in monitoring soil oil pollution when hyperspectral data are unavailable. PMID:23342066

Zhu, Linhai; Zhao, Xuechun; Lai, Liming; Wang, Jianjian; Jiang, Lianhe; Ding, Jinzhi; Liu, Nanxi; Yu, Yunjiang; Li, Junsheng; Xiao, Nengwen; Zheng, Yuanrun; Rimmington, Glyn M

2013-01-16

120

Effects of vegetable oil residue after soil extraction on physical-chemical properties of sandy soil and plant growth  

Microsoft Academic Search

Vegetable oil has the ability to extract polycyclic aromatic hydrocarbons (PAHs) from contaminated sandy soil for a remediation purpose, with some of the oil remaining in the soil. Although most of the PAHs were removed, the risk of residue oil in the soil was not known. The objective of this study was to evaluate the effects of the vegetable oil

Zongqiang GONG; Peijun LI; B. M. Wilke; Kassem Alef

2008-01-01

121

A dynamic global vegetation model for studies of the coupled atmosphere-biosphere system  

Microsoft Academic Search

This work presents a new dynamic global vegetation model designed as an extension of an existing surface-vegetation-atmosphere transfer scheme which is included in a coupled ocean-atmosphere general circulation model. The new dynamic global vegetation model simulates the principal processes of the continental biosphere influencing the global carbon cycle (photosynthesis, autotrophic and heterotrophic respiration of plants and in soils, fire, etc.)

G. Krinner; Nicolas Viovy; Nathalie de Noblet-Ducoudré; Jérôme Ogée; Jan Polcher; Pierre Friedlingstein; Philippe Ciais; Stephen Sitch; I. Colin Prentice

2005-01-01

122

Soils and vegetation of Santa Barbara Island, Channel Islands National Park, California, USA  

Microsoft Academic Search

The multifaceted development of an erosion surface on Santa Barbara Island, Channel Islands National Park, California, has led to this study of the relationship between soils and vegetation. A dry Mediterranean climate and past attempts at farming and introductions of alien species have led to vegetative degradation accompanied by both gully and surface erosion. Soil and vegetation analyses show this

William L. Halvorson; Dennis B. Fenn; William R. Allardice

1988-01-01

123

Wildfire frequency and its impacts on vegetation and soil in the north-eastern Alps  

Microsoft Academic Search

On the south-exposed slopes of the northern Austrian Alps, wildfires are surprisingly widespread. In the subalpine belt, the fires cause severe damage to vegetation and soil. The organic-rich rendzic soils may be almost completely destroyed and vegetation is degraded for decades or centuries. We investigate the role of fire on landscape dynamics in the area, which includes historical aspects, vegetation

O. Sass; M. Heel; M. Bayr; M. Jüttner; A. Friedmann; K.-F. Wetzel

2009-01-01

124

Only one isotopic water world: relevant processes at the soil-vegetation-atmosphere interface (Invited)  

NASA Astrophysics Data System (ADS)

The stable water isotopes of oxygen and hydrogen have been used to gain process and system knowledge about flow pathways, residence times, mixing and redistribution for many decades. In recent years the processes due to water-ecosystem interactions have become more relevant and new ideas how processes effect the isotopic signature of soil water and runoff have been postulated (e.g. Brooks et al, 2009, doi:10.1038/NGEO722). On the other side, new measurement techniques have increased the sampling rate of stable water isotopes in soils and plants tremendously. This allows us, for example, to measure stable isotope profiles in soils up to several meters in depth with sub-decimetre sampling interval within 2 days. Using these rich datasets together with physically-based modelling of water and isotope fluxes in soils and plants we investigated distinct processes at the soil-vegetation-atmosphere interface that influence the isotopic signature in soil water, recharge and runoff. We hypothesize that a combination of distinct processes in combination with the local climate can considerably alter the isotopic signature of streamwater or groundwater and that these processes are often not adequately considered. A literature survey revealed eight mechanisms, which can be grouped into redistribution, selection, leakage and uptake effects that have the potential to modify the isotopic signal in runoff or recharge. Applying the proposed modelling concepts to a variety of climate and vegetation conditions we can predict the impact of individual and multiple effects on the isotopic signature in runoff as well as on the isotope profiles in soils. The predicted profiles match well with the observed profiles. This framework allows us finally to predict if the isotopic signature is significantly altered under specific soil-vegetation-atmosphere conditions.

Weiler, M.; Gimbel, K.; Weber, R.

2010-12-01

125

Vegetation modeled as a water cloud  

Microsoft Academic Search

Because the microwave dielectric constant of dry vegetative matter is much smaller (by an order of magnitude or more) than the dielectric constant of water, and because a vegetation canopy is usually composed of more than 99% air by volume, it is proposed that the canopy can be modeled as a water cloud whose droplets are held in place by

E. P. W. Attema; Fawwaz T. Ulaby

1978-01-01

126

Dissolved organic carbon (DOC) concentrations in UK soils and the influence of soil, vegetation type and seasonality.  

PubMed

Given the lack of studies which measured dissolved organic carbon (DOC) over long periods, especially in non-forest habitat, the aim of this study was to expand the existing datasets with data of mainly non-forest sites that were representative of the major soil and habitat types in the UK. A further aim was to predict DOC concentrations from a number of biotic and abiotic explanatory variables such as rainfall, temperature, vegetation type and soil type in a multivariate way. Pore water was sampled using Rhizon or Prenart samplers at two to three week intervals for 1 year. DOC, pH, organic carbon, carbon/nitrogen (C:N) ratios of soils and slope were measured and data on vegetation, soil type, temperature and precipitation were obtained. The majority of the variation in DOC concentrations between the UK sites could be explained by simple empirical models that included annual precipitation, and soil C:N ratio with precipitation being negatively related to DOC concentrations and C:N ratio being positively related to DOC concentrations. Our study adds significantly to the data reporting DOC concentrations in soils, especially in grasslands, heathlands and moorlands. Broad climatic and site factors have been identified as key factors influencing DOC concentrations. PMID:22542300

van den Berg, Leon J L; Shotbolt, Laura; Ashmore, Mike R

2012-04-28

127

Use of B Isotopes to Investigate the Influence of the Vegetation on the Rate of Soil Weathering  

NASA Astrophysics Data System (ADS)

The rate at which soil minerals are weathered and the influence of the vegetal cover on the intensity and the nature of the reactions that release solutes from parent rocks to natural waters are still poorly understood. A way to investigate interactions between soil weathering and plant development is to focus on geochemical tools that are distinctively affected by these two processes and to monitor their behavior along yearly time scales, relevant to the soil/plant system. According to this approach, boron isotopes are particularly interesting because they undergo great isotopic fractionation during water/rock interactions and they are micro-nutrients essential for the life development. To monitor seasonal variations of the B fluxes in the soil/plant system, we benefit from the equipped experimental Strengbach catchment (Vosges, France) where vegetation samples, rainfalls, throughfalls, soil solutions at various depths (5, 10, 30, 60 cm) and spring waters are collected every 6 weeks from 2003 up to now. The observed B fluxes at the watershed scale reveal that it is controlled by the vegetation cycling because the amount of B involved in the vegetation cycling if about 5 times greater that its discharge at the outlet of the basin. Analyses of the B isotopic compositions of vegetation samples and throughfalls reveal unexpected isotopic fractionation that makes the vegetation-related B fluxes quit distinguishable from those controlled by water/rock interactions. The fact that the B geochemical cycle is regulated by the vegetation cycle together with an easy-to- follow isotopic signature makes then possible to determine the relative part of the vegetal activity from the soil weathering rate. We developed a 1D model of the B bio-geochemical cycle at the soil/plant scale that takes into account the transient features of the vegetation cycling and the water transport in soil. The results of the model reveal distinct reaction zones in soils according to its mineralogy and the ratio between the intensities of the vegetal activity and mineral weathering. This approach makes then possible to calculate the rate at which B is released from soil minerals and offer the opportunity to go further in the characterization of the controls and feedbacks that regulate interactions between soil and plant.

Lemarchand, D.; Cividini, D.; Chabaux, F.

2007-12-01

128

Lead contamination of soils and vegetation in the vicinity of a lead smelter in Nigeria  

Microsoft Academic Search

In a study to investigate the possible contamination of soil, vegetation and surface water from a lead smelter, samples of soil, edible vegetables and water were collected at varying distances from a smelting plant in the tin ore region of Nigeria. The total and extractable lead contents of the soils were analyzed by flame atomic absorption spectrophotometry and XRF spectrometry.

D. J. Oyedele; I. B. Obioh; J. A. Adejumo; A. F. Oluwole; P. O. Aina; O. I. Asubiojo

1995-01-01

129

Hydrologic modeling of soil water storage in landfill cover systems  

SciTech Connect

The accuracy of modeling soil water storage by two hydrologic models, CREAMS and HELP, was tested by comparing simulation results with field measurements of soil moisture in eight experimental landfill cover systems having a range of well-defined soil profiles and vegetative covers. Regression analysis showed that CREAMS generally represented soil moisture more accurately than HELP simulations. Soil profiles that more closely resembled natural agricultural soils were more accurately modeled than highly artificial layered soil profiles. Precautions for determining parameter values for model input and for interpreting simulation results are discussed.

Barnes, F.J.; Rodgers, J.C.

1987-01-01

130

Soil erosion and sediment yield and their relationships with vegetation cover in upper stream of the Yellow River.  

PubMed

Soil erosion is a significant concern when considering regional environmental protection, especially in the Yellow River Basin in China. This study evaluated the temporal-spatial interaction of land cover status with soil erosion characteristics in the Longliu Catchment of China, using the Soil and Water Assessment Tool (SWAT) model. SWAT is a physical hydrological model which uses the RUSLE equation as a sediment algorithm. Considering the spatial and temporal scale of the relationship between soil erosion and sediment yield, simulations were undertaken at monthly and annual temporal scales and basin and sub-basin spatial scales. The corresponding temporal and spatial Normalized Difference Vegetation Index (NDVI) information was summarized from MODIS data, which can integrate regional land cover and climatic features. The SWAT simulation revealed that the annual soil erosion and sediment yield showed similar spatial distribution patterns, but the monthly variation fluctuated significantly. The monthly basin soil erosion varied from almost no erosion load to 3.92 t/ha and the maximum monthly sediment yield was 47,540 tones. The inter-annual simulation focused on the spatial difference and relationship with the corresponding vegetation NDVI value for every sub-basin. It is concluded that, for this continental monsoon climate basin, the higher NDVI vegetation zones prevented sediment transport, but at the same time they also contributed considerable soil erosion. The monthly basin soil erosion and sediment yield both correlated with NDVI, and the determination coefficients of their exponential correlation model were 0.446 and 0.426, respectively. The relationships between soil erosion and sediment yield with vegetation NDVI indicated that the vegetation status has a significant impact on sediment formation and transport. The findings can be used to develop soil erosion conservation programs for the study area. PMID:21071065

Ouyang, Wei; Hao, Fanghua; Skidmore, Andrew K; Toxopeus, A G

2010-11-11

131

Soil-geomorphic heterogeneity governs patchy vegetation dynamics at an arid ecotone.  

PubMed

Soil properties are well known to affect vegetation, but the role of soil heterogeneity in the patterning of vegetation dynamics is poorly documented. We asked whether the location of an ecotone separating grass-dominated and sparsely vegetated areas reflected only historical variation in degradation or was related to variation in inherent soil properties. We then asked whether changes in the cover and spatial organization of vegetated and bare patches assessed using repeat aerial photography reflected self-organizing dynamics unrelated to soil variation or the stable patterning of soil variation. We found that the present-day ecotone was related to a shift from more weakly to more strongly developed soils. Parts of the ecotone were stable over a 60-year period, but shifts between bare and vegetated states, as well as persistently vegetated and bare states, occurred largely in small (<40 m2) patches throughout the study area. The probability that patches were presently vegetated or bare, as well as the probability that vegetation persisted and/or established over the 60-year period, was negatively related to surface calcium carbonate and positively related to subsurface clay content. Thus, only a fraction of the landscape was susceptible to vegetation change, and the sparsely vegetated area probably featured a higher frequency of susceptible soil patches. Patch dynamics and self-organizing processes can be constrained by subtle (and often unrecognized) soil heterogeneity. PMID:16676540

Bestelmeyer, Brandon T; Ward, Judy P; Havstad, Kris M

2006-04-01

132

MICROBIAL POPULATIONS ASSOCIATED WITH SOIL DEPTH, SOIL PHOSPHORUS, AND VEGETATION CHANGES DOWNWIND OF A CATTLE FEEDYARD  

Technology Transfer Automated Retrieval System (TEKTRAN)

In a previous study, the 30-year effect (1970 to 2000) of a 25,000-head beef cattle feedyard upon a downwind native shortgrass pasture was documented. Vegetation changes and a soil phosphorus (P) gradient with respect to distance from the feedyard were determined. The objective of this study was t...

133

Effects of vegetation structure on biomass accumulation in a coupled water-carbon-energy balance model in West Africa  

NASA Astrophysics Data System (ADS)

A myriad of interactions exist between vegetation and local climate for arid and semi-arid regions. Vegetation function, structure and individual behavior have enormous impacts on carbon-water-energy balances, which consequently influence local climate variability that, in turn, feeds back to the vegetation. In this study, a conceptual vegetation structure scheme is formulated and tested in a new carbon-water-energy coupled model to explore the importance of vegetation structure on equilibrium biomass states. Two different strategies of vegetation adaptation to water stress are included. Surface energy, water and carbon fluxes are simulated for a range of vegetation structures across a precipitation gradient in West Africa and optimal vegetation structures that maximize biomass for each precipitation regime are determined. Under dry conditions vegetation tries to maximize the Water Use Efficiency and Leaf Area Index as it tries to maximize carbon gain. However, as the vegetation can also engineer its environment by extracting water from the surrounding bare soil (thereby forming patches of vertical vegetation) it can also minimize its vegetation cover. With increasing precipitation, the vegetation tries to maximize its cover as it then can reduce water loss from bare soil while having maximum carbon gain due to a large Leaf Area Index. The competition between vegetation and bare soil determines a transition between a 'survival' regime to a 'growing' regime. The new modeling framework is useful to represent the effects of dynamic vegetation structure in coupled land-atmosphere feedback models.

Yin, Zun; Dekker, Stefan; van den Hurk, Bart; Dijkstra, Henk

2013-04-01

134

Vegetation modeling in Yakutia, northeastern Siberia: connecting to palaeovegetation simulation and model-data comparison  

NASA Astrophysics Data System (ADS)

Vegetation model is a useful tool to understand the impacts of climate change on ecosystems in the present, past and future. Simulation of the palaeovegetation can link the geographical pattern of vegetation in the past to pollen proxy and then test the palaeoclimate modeling. In this study we used an equilibrium vegetation model (BIOME4) and a dynamic vegetation model (LPJ) to predict the present-day vegetation pattern and their dynamic changes from 1901-2002 in Yakutia, an Arctic and sub-Arctic region in eastern Siberia, where is sensitive to climate change. Both the models characterized the basic features of regional vegetation pattern, function and their changes through time. The BIOME4 simulated a reasonable pattern of present biome distribution compared to the regional vegetation maps, the deciduous taiga-montane forests in the southern and central Yakutia, evergreen taiga-montane forests in the southwestern mountainous region and in the eastern coast, shrub tundra and dwarf shrub tundra in the northwest and northeast mixed with temperate xerophytic shrubland. In the NW Yakutia the LPJ demonstrated a dynamic change of local vegetation during the past 102 years responding to the changed climates. Forest and shrub covered the large area from the beginning to the 1950s of the 20th Century. Tundra extended from the west to the east during 1960s to 1970s. The woody plants extended in 1980s and in late 1990s to early 21st Century and grasses extended in 1990s. The performance of global vegetation models in regional study is well, but problems still existed. More plant functional types especially the shrubs and grasses and climatic constraints to them should be taken into account when improving the models. Soil water-related parameters should be redefined. The modules of permafrost, snow, and fire should be added or modified. Regional input data of climates, vegetation and soils at finer resolutions will be obtained from the regional and local studies.

Ni, J.; Herzschuh, U.

2009-04-01

135

Interactions between vegetation, hydrology, and soil biogeochemistry in a Southern California annual grassland  

NASA Astrophysics Data System (ADS)

The soil carbon-nitrogen cycle is an integral component of the surface hydrologic system. Vegetation dynamics influence and respond to soil water and nitrogen availability, which are also linked through biogeochemical (e.g. decomposition, mineralization) and physical processes (e.g. drainage, transpiration). With anticipated changes in precipitation variability and reactive nitrogen inputs, a holistic approach toward understanding this coupled system is necessary. Leveraging data from a factorial irrigation-fertilization experiment in a Mediterranean-like annual grassland, we search for evidence of feedbacks between vegetation, nitrogen availability, and hydrology. Our analysis demonstrates that the water balance is relatively insensitive to an exogenous increase in nitrogen availability, due to a trade-off between canopy density and leaf conductance. This is consistent with the notion that, in semi-arid ecosystems, canopy structure and physiology work in an integrated fashion to maintain a transpiration flux tightly controlled by soil and climate properties. We explain this behavior with a model constrained by the hydraulic capacity of the soil-vegetation-atmosphere pathway.

Parolari, A.; Goulden, M.; Bras, R. L.

2011-12-01

136

Linking models and data on vegetation structure  

NASA Astrophysics Data System (ADS)

For more than a century, scientists have recognized the importance of vegetation structure in understanding forest dynamics. Now future satellite missions such as Deformation, Ecosystem Structure, and Dynamics of Ice (DESDynI) hold the potential to provide unprecedented global data on vegetation structure needed to reduce uncertainties in terrestrial carbon dynamics. Here, we briefly review the uses of data on vegetation structure in ecosystem models, develop and analyze theoretical models to quantify model-data requirements, and describe recent progress using a mechanistic modeling approach utilizing a formal scaling method and data on vegetation structure to improve model predictions. Generally, both limited sampling and coarse resolution averaging lead to model initialization error, which in turn is propagated in subsequent model prediction uncertainty and error. In cases with representative sampling, sufficient resolution, and linear dynamics, errors in initialization tend to compensate at larger spatial scales. However, with inadequate sampling, overly coarse resolution data or models, and nonlinear dynamics, errors in initialization lead to prediction error. A robust model-data framework will require both models and data on vegetation structure sufficient to resolve important environmental gradients and tree-level heterogeneity in forest structure globally.

Hurtt, G. C.; Fisk, J.; Thomas, R. Q.; Dubayah, R.; Moorcroft, P. R.; Shugart, H. H.

2010-06-01

137

Soil temperature effects on uptake of cadmium and zinc by vegetables grown on sludge-amended soil  

Microsoft Academic Search

The effects of soil temperature on the uptake of heavy metals by plants grown on sludge-amended soil has not been established. A field experiment was initiated in 1975 to determine uptake of Cd and Zn by several vegetables from Sango sil amended with 224 metric tons\\/ha of an anaerobically digested sewage sludge. A variety of commonly grown garden vegetables were

P. M. Giordano; D. A. Mays; A. D. Jr. Behel

1979-01-01

138

Productivity of wet soils: Biomass of cultivated and natural vegetation  

SciTech Connect

Wet soils, soils which have agronomic limitations because of excess water, comprise 105 million acres of non-federal land in the conterminous United States. Wet soils which support hydrophytic plants are ''wetlands'', and are some of the most productive natural ecosystems in the world. When both above- and belowground productivity are considered, cattail (Typha latifolia) is the most productive temperate wetland species (26.4 Mg/ha/year). Both cattail and reed (Phragmites australis) have aboveground productivities of about 13 Mg/ha/year. Although average aboveground yields of reed canarygrass (Phalaris arundinacea) are lower (9.5 Mg/ha/year), techniques for its establishment and cultivation are well-developed. Other herbaceous wetland species which show promise as biomass crops include sedge (Carex spp.), river bulrush (Scirpus fluviatilis) and prairie cordgrass (Spartina pectinata). About 40% of wet soils in the conterminous US are currently cultivated, and they produce one-quarter of the major US crops. Most of this land is artificially drained for crops such as corn, soybeans, and vegetables. US wetlands are drained for agriculture at the rate of 223,000 ha/yr. Paddies flooded with water are used to grow rice, cranberries, and wild rice. Forage and live sphagnum moss are products of undrained wetlands. A number of federal and state regulations apply to the draining or irrigation of wetlands, but most do not seriously restrict their use for agriculture. 320 refs., 36 tabs.

Johnston, C.A.

1988-12-01

139

Sulfamethazine sorption to soil: vegetative management, pH, and dissolved organic matter effects  

Technology Transfer Automated Retrieval System (TEKTRAN)

Elucidating veterinary antibiotic (VA) interactions with soil is important for assessing and mitigating possible environmental hazards. Objectives of this study were to investigate the effects of vegetative management, soil physical and chemical properties, and manure-derived dissolved organic matte...

140

Changes in Vegetation and Surface Soil Properties Following Irrigation of Woodlands with Municipal Wastewater.  

National Technical Information Service (NTIS)

The impact of municipal wastewater irrigation on soil water quality, vegetation growth and nutrient status, soil chemistry, and humus decomposition in a 20-year old red pine plantation and maple-beech hardwood forest in southern Michigan was studied. The ...

D. P. White G. Schneider E. A. Erickson

1975-01-01

141

Inclusion of vegetation in the Town Energy Balance model for modeling urban green areas  

NASA Astrophysics Data System (ADS)

Cities impact both local climate, through urban heat islands, and global climate, because they are an area of heavy greenhouse gas release into the atmosphere due to heating, air conditioning and traffic. Including more vegetation into cities is a planning strategy having possible positive impacts for both concerns. Improving vegetation representation into urban models will allow to address more accurately these questions. This paper presents an improvement of the TEB urban canopy model. Vegetation is directly included inside the canyon, allowing shadowing of grass by buildings, better representation of urban canopy form, and, a priori, a more accurate simulation of canyon air microclimate. The development is performed so that any vegetation model can be used to represent the vegetation part. Here the ISBA model is used. The model results are compared to microclimatic and evaporation measurements performed in small courtyards in a very arid region of Israel. Two experimental landscaping strategies - bare soil or irrigated grass in the courtyard - are observed and simulated. The new version of the model with integrated vegetation performs better than if vegetation is treated outside the canyon. Surface temperatures are closer to the observations, especially at night when radiative trapping is important. The integrated vegetation version simulates a more humid air inside the canyon. The microclimatic quantities are better simulated with this new version. This opens opportunities to study with better accuracy the urban microclimate, down to the micro (or canyon) scale.

Lemonsu, A.; Masson, V.; Shashua-Bar, L.; Erell, E.; Pearlmutter, D.

2012-05-01

142

Seasonal changes in surface soil moisture and vegetation observed by ERS-1 SAR over temperate grassland and semi-arid savannah  

NASA Astrophysics Data System (ADS)

Soil moisture exerts an important control on the transfer of energy and water at the land surface and its availability determines, to a large extent, the development of vegetation. Satellite remote sensing using synthetic aperture radar has the potential to monitor spatial and temporal changes in surface soil moisture provided the effects of, primarily, vegetation and surface roughness are understood. The results obtained from ground validation measurements undertaken during an annual vegetation cycle in contrasting temperate and semi-arid climates enabled the sensitivity of the SAR to be tested over a wide range of soil moisture and vegetation conditions. In the UK, flat, grassland sites were used to simplify the modeling of vegetation over three contrasting soil types. Both manually read and data-logged instruments were used to monitor moisture conditions both at the surface and within the soil moisture profile for modeling their interrelationships over time. Vegetation parameters were determined through destructive sampling. In Niger the soils were of almost pure sand under both the natural vegetation of fallow savannah and the main crop of millet. As a result of the high permeability of the sand, the timing of SAR data acquisition relative to the last rainfall event was believed to be an important factor affecting radar backscatter. For both areas, seasonal variations in radar backscatter were present and evidence to demonstrate the contribution of the vegetation and soil components is given.

Blyth, Ken

1995-01-01

143

Sensitivity of global vegetation models to present-day climate simulated by global climate models  

NASA Astrophysics Data System (ADS)

This paper provides an evaluation of the reliability of several climate models with respect to ecosystem modeling and describes a methodology for undertaking such an evaluation. The global climate models (GCM) and global vegetation models used in this study are linked in a one way mode (i.e., no feedback from the vegetation model to the GCM is allowed), and the vegetation distributions are compared with those obtained using observed climatology. The aim of this study is to identify which simulated ecosystems are sensitive to the biases of the climate simulations. Two global static vegetation models, BIOME-1 and a version of the Holdridge scheme, are used in conjunction with several present-day climate simulations. The climate simulations employed come from the GCMs participating in the Model Evaluation Consortium for Climate Assessment project. The results indicate that the overall performance of coarse resolution GCMs with respect to vegetation prediction is poor. The discrepancies between vegetation distributions computed from observed and simulated climatologies represent more than 50% of land area. The comparison of vegetation distributions shows that there are some common tendencies amongst these GCMs to induce the overprediction or underprediction of certain biomes. For example, the biomes belonging to dry climate regions are underpredicted, and the woodlands and temperate/cold forests are overpredicted. The climatic variables responsible for the discrepancies between vegetation predictions are identified, and it appears that the differences in vegetation predictions are overall due to the overestimation of the soil moisture index and precipitation, to the overestimation of growing degree days, and to the underestimation of the annual minimum temperatures. In summary, this research has shown that the prediction of biomes using simulated climatologies is not yet fully satisfactory; however, it is possible to increase our level of confidence in the prediction of vegetation by carefully evaluating the performance of the vegetation models driven by simulated climatologies and by identifying the causes of the biases.

Ciret, C.; Henderson-Sellers, A.

1997-09-01

144

Modelling light use efficiency using vegetation index and land surface temperature from MODIS in Harvard Forest  

Microsoft Academic Search

Light use efficiency (LUE) is of great importance for carbon cycle and climate change research. This study presents a new LUE model incorporation of vegetation indices (VIs) and land surface temperature (LST) derived from the Moderate-Resolution Imaging Spectroradiometer (MODIS) in Harvard Forest. Three indices, including the normalized difference vegetation index (NDVI), the two-band enhanced vegetation index (EVI2) and the soil-adjusted

Chaoyang Wu; Zheng Niu

2011-01-01

145

Modelling light use efficiency using vegetation index and land surface temperature from MODIS in Harvard Forest  

Microsoft Academic Search

Light use efficiency (LUE) is of great importance for carbon cycle and climate change research. This study presents a new LUE model incorporation of vegetation indices (VIs) and land surface temperature (LST) derived from the Moderate-Resolution Imaging Spectroradiometer (MODIS) in Harvard Forest. Three indices, including the normalized difference vegetation index (NDVI), the two-band enhanced vegetation index (EVI2) and the soil-adjusted

Chaoyang Wu; Zheng Niu

2012-01-01

146

Terrestrial biogeochemical cycling and vegetation response to climate in an earth system model  

SciTech Connect

We are developing (1) a seasonal model of terrestrial productivity and biogeochemical cycling (TERRA) and (2) a model of vegetation response to climate (HABITAT). Both of these models are designed to be components of an Earth System Model being developed at Lawrence Livermore National Laboratory (LLNL). We have implemented the grid-cell model of TERRA and have calibrated it for the 17 vegetation types that it simulates. In a sensitivity analysis, we have found that total system response is most sensitive to parameters affecting soil moisture content which, in turn, affects soil respiration. Albedo was found to be an important factor in tundra systems. Carbon sequestration was strongly influenced by only a handful of parameters for each of the five types discussed in this paper. Parameters affecting soil respiration, soil moisture, littefall rate, CO[sub 2] assimilation, C:N ratio in litterfall, and nitrogen uptake were, in most circumstances, found to be the most important parameters. As an initial phase in constructing the vegetation response model, we have investigated an existing method of classifying vegetation life zones based on total annual precipitation and average monthly temperature to determine if this method discriminates between vegetation types. We used global vegetation and climatic data sets for this analysis. We found that these variables lack power to resolve vegetation types.

Kercher, J.R.; Axelrod, M.C.; MacCracken, M.C. (Lawrence Livermore National Lab., CA (United States)); Chambers, J.Q. (Lawrence Livermore National Lab., CA (United States) California Univ., Santa Barbara, CA (United States). Dept. of Biological Sciences)

1992-10-01

147

Vegetation controls on soil water dynamics and runoff production in a headwater catchment in the Ore Mountains  

NASA Astrophysics Data System (ADS)

Spatial variability of soil hydraulic parameters and soil structures dominate surface runoff production as well as soil water dynamics at the hillslope and headwater scale. These seem to be common grounds in soil physics and was our credo when we instrumented a small headwater (10 km2) of the Weiáeritz with six rain gauges, a meteorological station, shallow piezometers and two STDR clusters to investigate soil moisture control on runoff and surface runoff production. Both TDR clusters consist of 35 individual TDR sensors of 60 cm depth covering an extend of 15m by 15m. Cluster 1 one is located at a grassland site, cluster 2 is located in a nearby forested area. The soil at the grassland site is a clayey loam with a high content of organic matter, a very large porosity of 0.63 in the top 20 cm and a soil hydraulic conductivity of on average around 4 * 10-5 m/s. Soil at the forested site is similar with an even higher infiltrability and higher organic content of the top soil. Both soils exhibit a high gravel content and rather high spatial variability of soil properties. Despite of this large heterogeneity of soil parameters, we found that vegetation exerts crucial control on average soil moisture dynamics, its spatial variability and most interesting on the development of the spatial covariance structure of the soil moisture patterns. Correlation length at the grassland site was rather short but increased with increasing average wetness. So did the nugget to sill ratio of the variogram. At the forested site correlation length did not vary with average wetness and was constantly 50% of the maximum probe distance. We therefore conclude that the correlation structure at the forested site is dominated by the pattern of through-fall and interception and therefore vegetation. During a modelling exercise we found that despite of the large heterogeneity of the soils a homogeneous soil setup allowed a good reproduction of observed soil moisture dynamics at the hourly scale for a period of more than 3 months. At both sites simulations were most sensitive to small changes of key plant parameters. Especially root depth, leaf area index and plant coverage and their evolution during the vegetation phase were of prime importance for a good model performance. Surprisingly, evapo-transpiration and thus vegetation determines near surface soil moisture dynamics and therefore surface runoff production at this headwater catchment. Consequently, survey of key plant parameters such as leaf area index, plant coverage and their evolution during the vegetation phase is of prime importance for model predictions of soil moisture dynamics and surface runoff production in this headwater. Many process-orientated model studies put their major efforts into assessment of soil parameters and treat vegetation as something static that can be characterized by a few constant parameters. Model studies ? including some of our own ? often just devote a single statement such as ?vegetation was short grass and parameters were taken from the literature? to characterize vegetation in their model structure. This story shows that sometimes even grown up process hydrologists don?t see the wood for the trees.

Zehe, E.; Graeff, T.; Schlaeger, S.; Morgner, M.; Bauer, A.

2009-04-01

148

The global carbon dioxide flux in soil respiration and its relationship to vegetation and climate  

Microsoft Academic Search

Measured rates of soil respiration from terrestrial and wetland ecosystems are reviewed to define the annual global CO2 flux from soils, identify uncertainties in the global flux estimates, and to investigate the influences of temperature, precipitation, and vegetation on soil respiration rates. The annual global CO2 flux from soils is estimated to average 68 +\\/- 4 PgC\\/yr, based on extrapolations

J. W. Raich; W. H. Schlesinger

1992-01-01

149

Winter soil respiration from different vegetation patches in the Yellow River Delta, China.  

PubMed

Vegetation type and density exhibited a considerable patchy distribution at very local scales in the Yellow River Delta, due to the spatial variation of soil salinity and water scarcity. We proposed that soil respiration is affected by the spatial variations in vegetation type and soil chemical properties and tested this hypothesis in three different vegetation patches (Phragmites australis, Suaeda heteroptera and bare soil) in winter (from November 2010 to April 2011). At diurnal scale, soil respiration all displayed single-peak curves and asymmetric patterns in the three vegetation patches; At seasonal scale, soil respiration all declined steadily until February, and then increased to a peak in next April. But, the magnitude of soil respiration showed significant differences among the three sites. Mean soil respiration rates in winter were 0.60, 0.45 and 0.17 ?mol CO(2) m(-2) s(-1) for the Phragmites australis, Suaeda heteroptera and bare soil, respectively. The combined effect of soil temperature and soil moisture accounted for 58-68 % of the seasonal variation of winter soil respiration. The mean soil respiration revealed positive and linear correlations with total N, total N and SOC storages at 0-20 cm depth, and plant biomass among the three sites. We conclude that the patchy distribution of plant biomass and soil chemical properties (total C, total N and SOC) may affect decomposition rate of soil organic matter in winter, thereby leading to spatial variations in soil respiration. PMID:22576142

Han, Guangxuan; Yu, Junbao; Li, Huabing; Yang, Liqiong; Wang, Guangmei; Mao, Peili; Gao, Yongjun

2012-05-11

150

Winter Soil Respiration from Different Vegetation Patches in the Yellow River Delta, China  

NASA Astrophysics Data System (ADS)

Vegetation type and density exhibited a considerable patchy distribution at very local scales in the Yellow River Delta, due to the spatial variation of soil salinity and water scarcity. We proposed that soil respiration is affected by the spatial variations in vegetation type and soil chemical properties and tested this hypothesis in three different vegetation patches ( Phragmites australis, Suaeda heteroptera and bare soil) in winter (from November 2010 to April 2011). At diurnal scale, soil respiration all displayed single-peak curves and asymmetric patterns in the three vegetation patches; At seasonal scale, soil respiration all declined steadily until February, and then increased to a peak in next April. But, the magnitude of soil respiration showed significant differences among the three sites. Mean soil respiration rates in winter were 0.60, 0.45 and 0.17 ?mol CO2 m-2 s-1 for the Phragmites australis, Suaeda heteroptera and bare soil, respectively. The combined effect of soil temperature and soil moisture accounted for 58-68 % of the seasonal variation of winter soil respiration. The mean soil respiration revealed positive and linear correlations with total N, total N and SOC storages at 0-20 cm depth, and plant biomass among the three sites. We conclude that the patchy distribution of plant biomass and soil chemical properties (total C, total N and SOC) may affect decomposition rate of soil organic matter in winter, thereby leading to spatial variations in soil respiration.

Han, Guangxuan; Yu, Junbao; Li, Huabing; Yang, Liqiong; Wang, Guangmei; Mao, Peili; Gao, Yongjun

2012-07-01

151

Stability of banded vegetation patterns under seasonal rainfall and limited soil moisture storage capacity  

Microsoft Academic Search

The delicate equilibrium of soil moisture and biomass may become unstable under water scarcity conditions causing banded vegetation patterns to form on hillsides of semi-arid catchments. Soil related processes that induce instability (namely: soil moisture advection and diffusion), have been evaluated numerically for different rainfall regimes. This study addresses the combined influence of some relevant soil characteristics, and the effect

Nadia Ursino; Samuel Contarini

2006-01-01

152

Influence of planting patterns on fluoroquinolone residues in the soil of an intensive vegetable cultivation area in northern China.  

PubMed

Recent studies have demonstrated the persistence of antibiotics in soil, especially in areas of vegetable cultivation. However, there are very few studies of the influence of planting regimes on the levels of antibiotic pollution. This work introduces geographical-detector models to investigate the relationship between planting patterns (vegetable planting model, manure type and quantity, planting age, greenhouse area, and topographic elevation) and residual fluoroquinolones (FQs) in soil in a pilot project in Shouguang County, Shandong Province (the largest vegetable-producing area in China). The results led to the following findings. 1. The vegetable planting model is the major determinant of the spatial stratification of FQ in the soil. For example, the "cucumber-cucumber" model (growing cucumbers after cucumbers) has a three-fold power of determinant compared to the "pepper-melon" model (growing melons after peppers). 2. Planting age (years with continuous vegetable cultivation) does not necessarily affect the spatial distribution of FQ owing to their relatively short degradation period. 3. Interactions between risk factors were more significant than the individual factors for FQ pollution. In particular, the interaction between the vegetable planting model and amount of manure resulted in the highest pollution level. The findings of the present study make it possible to introduce effective and practical measures to alleviate pollution of soils by FQ in the study area. Adjustment of the vegetable cultivation models and application of chicken manure (less than 6 kg/m(2) manure annually with a more dry than fresh manure) could be an effective and flexible approach to alleviate FQ pollution. PMID:23644280

Li, Xuewen; Xie, Yunfeng; Wang, Jinfeng; Christakos, George; Si, Jiliang; Zhao, Huinan; Ding, Yanqiang; Li, Jie

2013-04-30

153

Impacts of Scale and Heterogeneity in Dynamic Global Vegetation Models  

NASA Astrophysics Data System (ADS)

Dynamic Global Vegetation Models (DGVMs) are crucial components in coupled land-climate simulations for representing the feedbacks between the atmosphere and terrestrial biosphere. Accurate predictions of the impact of climate change depend on well-functioning DGVMs. Construction of such complex models necessitates the encoding of a large number of assumptions, both implicit and explicit. One particular assumption that is generally implicit in this class of models is the homogeneity of land cover within a grid cell. The spatial distribution of land cover, and in particular Plant Functional Types (PFTs), is often not considered. For some model processes this is equivalent to assuming that vegetation is homogeneous within the grid cell, which is typically in the order of 1 by 1 degree in size. This is clearly not the case for large areas of the surface of the Earth. A key process that will be impacted by this assumption is the net accumulation of soil carbon in a grid cell. Carbon enters soil in the form of litter from vegetation and is removed in the form of carbon dioxide respired by soil micro-organisms. Typically soil carbon in a DGVM grid cell is represented by a single horizontal box with a number of vertical layers. Each PFT drops litter into the same soil pool. Consequently the build-up of soil carbon under a grassland, for example, may be influenced by the presence of a deciduous forest in the same grid cell even though they may be physically separated by a significant distance. Clearly the model predictions, at least in terms of soil carbon and heterotrophic respiration, are scale dependent under these assumptions. Running the DGVM at a different resolution would potentially change the nature of PFTs contributing to a given area of soil. The other limit, which is not generally considered, would be to model each PFT with its own independent soil pool. However, this is also an unrealistic description of some areas of the land surface which may exist as a highly heterogeneous matrix. This paper introduces a simple index of heterogeneity that is generated from satellite derived land cover information (the GLC2000 data set) across the global land surface. Prior to transformation the data is mapped into notional PFTs. The resulting information can then be used examine the impacts of assumptions about heterogeneity. The resolution of the GLC2000 data is 1km and so there is an implicit assumption that this scale of data is sufficient to represent the heterogeneity of processes at the 1 by 1 degree scale. The Sheffield Dynamic Global Vegetation Model is used to predict global Net Ecosystem Productivity (NEP, the net accumulation of carbon that is the balance between photosynthesis and respiration) under both limits: that the PFTs within a grid cell all share the same resources and that they are independent. The heterogeneity map is then used to recombine the model outputs by weighting the contribution of each scenario based on the local heterogeneity in vegetation cover. Results, presented for the global land surface, show regions in which the implicit assumptions of homogeneity and scaling have a large impact in model predictions in NEP.

Quaife, T. L.

2010-12-01

154

Water regime of soils under the different vegetative cover, the Giant Mountains, Czech Republic  

Microsoft Academic Search

Several monitored plots, located in the Giant Mountains in different positions (valley, slope), are covered by different vegetation (dwarf pine forest, spruce forest, meadow). Soil moisture properties in relation to vegetative cover (dwarf pine versus grassland stands) were studied from the year 2000 to 2006. The main goal was to analyse chosen rainfall-runoff periods with respect to diferent vegetative cover.

I. J. Dvorak; M. Tesar; J. Dohnal

2009-01-01

155

LONG-TERM SOIL AND VEGETATION RECOVERY IN FIVE SEMIARID MONTANA GHOST TOWNS  

Microsoft Academic Search

Five semiarid Montana ghost towns abandoned for more than 45 years were studied to understand better the nature of soil and vegetation recovery following severe human impacts. Discriminant analysis was used to interpret and classify variation among land-use intensity groups. Recovery at the five towns was strongly linked to the degree of the initial soil disturbance, vegetation type, and precipitation.

Paul A. Knapp

1991-01-01

156

Temporal and spatial variation in how vegetation alters the soil moisture response to climate manipulation  

Microsoft Academic Search

Aims Soil water balance, key for ecosystem processes, is determined by multiple factors, including precipitation, temperature, slope and vegetation. How these interact with climate change and the relevant time scale of the interactions are poorly understood. We investigated the interplay among climate change, local abiotic conditions (slope) and biotic factors (vegetation or not) on soil water balance in a steppe

Pierre Liancourt; Bazartseren Boldgiv; Brent R. Helliker; Alain F. Plante; Peter S. Petraitis; Brenda B. Casper

2012-01-01

157

Effects of Ground Cover and Leaf Area on the Spectral Reflectance of Vegetation-Soil Target.  

National Technical Information Service (NTIS)

The relations between spectral reflectance, percent ground cover, and leaf area index (LAI) for vegetation-soil targets were evaluated for green vegetation against either a light-toned sand and a dark-toned organic loam soil. The percent ground cover and ...

M. B. Satterwhite P. Henley

1982-01-01

158

Applicability of site-specific pedotransfer functions and rosetta model for the estimation of dynamic soil hydraulic properties under different vegetation covers  

Microsoft Academic Search

Background, Aims, and Scope  During the last decades, different methods have been developed to determine soil hydraulic properties in the field and laboratory.\\u000a These methodologies are frequently time-consuming and\\/or expensive. An indirect method, named Pedotransfer Functions (PTFs),\\u000a was developed to predict soil hydraulic properties using other easily measurable soil (physical and chemical) parameters.\\u000a This work evaluates the use of the PTFs

Carles M. Rubio; Ferran El Catolic

2008-01-01

159

Vegetation study in support of the design and optimization of vegetative soil covers, Sandia National Laboratories, Albuquerque, New Mexico.  

SciTech Connect

A vegetation study was conducted in Technical Area 3 at Sandia National Laboratories, Albuquerque, New Mexico in 2003 to assist in the design and optimization of vegetative soil covers for hazardous, radioactive, and mixed waste landfills at Sandia National Laboratories/New Mexico and Kirtland Air Force Base. The objective of the study was to obtain site-specific, vegetative input parameters for the one-dimensional code UNSAT-H and to identify suitable, diverse native plant species for use on vegetative soil covers that will persist indefinitely as a climax ecological community with little or no maintenance. The identification and selection of appropriate native plant species is critical to the proper design and long-term performance of vegetative soil covers. Major emphasis was placed on the acquisition of representative, site-specific vegetation data. Vegetative input parameters measured in the field during this study include root depth, root length density, and percent bare area. Site-specific leaf area index was not obtained in the area because there was no suitable platform to measure leaf area during the 2003 growing season due to severe drought that has persisted in New Mexico since 1999. Regional LAI data was obtained from two unique desert biomes in New Mexico, Sevilletta Wildlife Refuge and Jornada Research Station.

Peace, Gerald (Jerry) L.; Goering, Timothy James (GRAM inc., Albuquerque, NM); Knight, Paul J. (Marron and Associates, Albuquerque, NM); Ashton, Thomas S. (Marron and Associates, Albuquerque, NM)

2004-11-01

160

Influence of vegetation, soil and antecedent soil moisture on the variability of surface runoff coefficients at the plot scale in the eastern alps  

NASA Astrophysics Data System (ADS)

Modelling the runoff of a catchment in a high spatial resolution, you need to know the potential of a single plot to generate surface runoff. The portion of surface runoff is highly significant for storm runoff events, accordingly, it mainly forms the hydrograph. In this study, the influence of vegetation, soil features and antecedent soil moisture on generating surface runoff at the plot scale have been analysed. To achieve an appropriate fit of the plots, a plot sizes between 50 and 400 m² were chosen. The rainfall intensities ranged between 10 mm/h and 100 mm/h. Based on 260 rain simulations with a transportable sprinkling instrumentation on representative plots in the eastern Alps (Austria, Italy, Germany), including investigations on land-use, vegetation cover and soil physical characteristics, various soil-vegetation complexes and their surface runoff processes have been be analysed. Additionally, we investigated flow paths, travel distance, infiltration hindrance, flow resistance and overland flow velocity. The soil water status was monitored by using TDR-probes, which had been installed in two profiles within the plot in different depths ranging from 5 cm to 40 cm. For every sprinkling experiment, a surface runoff coefficient was calculated as the ratio between total rainfall amount and surface runoff. With this substantial dataset, the regression analysis was used to examine the influence of the hydrological key factors as soil, vegetation and initial soil moisture condition on the distribution functions of the surface runoff coefficient. The first results show that the vegetation cover is very important for the surface runoff. If initial soils are covered by alpine or sub-alpine pioneering vegetation surface runoff can be found very scarce. If these initial soils are covered i.e. by subalpine nardus grasslands the surface runoff coefficients range from 0.1 up to 0.8. On the other hand it can be shown that soils with a high bulk density mainly generate very high surface runoff coefficients, independent of the antecedent soil moisture. Cambisols show a great variance of surface runoff coefficients. These results are the basis for the characterisation of different soil-vegetation complexes by their surface runoff coefficient and they also describe the potential surface runoff of a catchment.

Chifflard, P.; Kohl, B.; Markart, G.; Kirnbauer, R.

2009-04-01

161

Modeling Hydrologic and Vegetation Responses in Freshwater Wetlands  

NASA Astrophysics Data System (ADS)

Wetlands constitute 6 - 7 % of the Earth's land surface and provide various critical ecosystem services such as purifying the air and water, mitigating floods and droughts, and supporting wildlife habitats. Despite the importance of wetlands, they are under threat of degradation by human-induced land use changes and climate change. Even if the value of wetlands is recognized, they are often not managed properly or restored successfully due to an inadequate understanding of the ecosystems and their responses to management scenarios. A better understanding of the main components of wetlands, namely the interdependent hydrologic and vegetation systems, and the sensitivity of their responses to engineering works and climate change, is crucial for the preservation of wetlands. To assess these potential impacts, a model is developed in this study for characterizing the coupled dynamics between soil moisture and plant biomass in wetland habitats. The hydrology component of the model is based on the Richards' equation and simulates spatially-varying groundwater movement and provides information on soil moisture at different depths. The plant growth component of the model is described through an equation of the Lotka-Volterra type modified for plant growth dynamics and is adapted from published literature. The two components are coupled via transpiration and ecosystem carrying capacity for plants. Transpiration is modeled for both unsaturated and saturated zones, while the carrying capacity describes limiting oxygen and subsequent nutrient availability in the soil column as a function of water table depth. Vegetation is represented by two species characteristic of mudflat herbaceous plants ranging from facultative wetland to upland plants. The model is first evaluated using a simplified domain and the hydrological information available in the RG2 site of the Everglades wetlands region. The modeled water table fluctuations in general are comparable to field data collected on-site, indicating the potential of the model in capturing soil moisture dynamics. Further application of the model for impact assessments demonstrates that drainage of wetlands resulting in groundwater drawdown is expected to produce appreciable effects on vegetation biomass response. The model developed in this study simulates the coupled and spatially-varying groundwater movement and plant growth dynamics, which allows researchers to better understand and protect the integrated hydrologic and vegetation systems of wetlands worldwide.

Chui, Ting Fong May; Low, Swee Yang; Liong, Shie-Yui

2010-05-01

162

Vegetation Dynamics and Soil Water Balance in a Water-limited Mediterranean Ecosystem on Sardinia, Italy  

NASA Astrophysics Data System (ADS)

Semi-arid regions, such as around the Mediterranean, suffer from broad desertification processes produced by both natural and human influences. Mediterranean ecosystems are commonly heterogeneous savanna-like ecosystems, with contrasting plant functional types (PFTs, e.g., grass and woody vegetation) competing for the water use. At the same time the structure and function of the vegetation regulates the exchange of mass, energy and momentum across the biosphere-atmosphere interface, influencing strongly the soil water budget. With the objective to investigate vegetation dynamics, soil water budget and land-surface fluxes interactions in a water-limited ecosystem, an extensive field campaign in a Mediterranean water-limited field is performed, and a parsimonious and robust vegetation dynamic model (VDM) is coupled to a 3-component (bare soil, grass and woody vegetation) LSM. The case study is in Orroli, situated in the mid-west of Sardegna within the Flumendosa river watershed. Sardinia is a region that suffers from water scarcity, and the Flumendosa basin plays a primary role in the water supply for much of southern Sardinia, including the island's biggest city, Cagliari. The site landscape is a mixture of Mediterranean patchy vegetation types: trees, including wild olives and cork oaks, different shrubs and herbaceous species. An extensive field campaign started in April 2003. More than three years of data are available. Interestingly, hydrometeorological conditions of the monitored years strongly differ, with dry and wet years in turn, and a wide range of hydrometeorological conditions can be analyzed. Land-surface fluxes and CO2 fluxes are estimated by an eddy correlation technique based micrometeorological tower. Soil moisture profiles were also continuously estimated using water content reflectometers and gravimetric method, and periodically leaf area index (LAI) estimates of both plant types are made using the Accupar LP-80 by Decagon Devices Inc. Furthermore, two high spatial resolution (2.8 m) Quickbird satellite images were acquired in August of 2003 and March 2004 for defining the spatial organization of the main land cover types around the tower for two contrasting seasons of the year (Summer and Spring). A parsimonious ecohydrologic model is developed. The VDM computes the change in biomass over time as difference between the rate of production (e.g., photosynthesis) and the rate of destruction (e.g., respiration and senescence). VDM incorporates two PFTs using basic rules regarding competition for a limiting resource. The VDM is then coupled to a 3-component LSM, with the VDM providing the green biomass and the LAI evolution through time, and the LSM using this information in the computation of the land surface fluxes and updating the soil water content in the root-zone. The coupled VDM-LSM model is successfully tested for the case study, demonstrating high model performance for the wide range of eco-hydrologic conditions. The inclusion of the VDM in the LSM is demonstrated to be essential when studying the climate-soil-vegetation interactions of these water-limited ecosystems. Results demonstrate also that vegetation dynamics are strongly influenced by the inter-annual variability of atmospheric forcing, with grass leaf area index changing significantly each spring season according to seasonal rainfall amount.

Montaldo, N.; Albertson, J. D.; Mancini, M.

2007-12-01

163

Influence of variation of soil spatial heterogeneity on vegetation restoration  

Microsoft Academic Search

Numerous hypotheses and conceptional models dealing with the grassland desertification or degradation processes recognize\\u000a that the invasion of shrubs in grasslands is the most striking feature of the variation of vegetation patterns in the grassland\\u000a degradation or desertification processes in arid and semiarid regions. This is because the invasion of shrubs in grasslands\\u000a increases the heterogeneity of the temporal and

Xinrong Li

2005-01-01

164

Exploring field vegetation reflectance as an indicator of soil contamination in river floodplains  

Microsoft Academic Search

This study investigated the relation between vegetation reflectance and elevated concentrations of the metals Ni, Cd, Cu, Zn and Pb in river floodplain soils. High-resolution vegetation reflectance spectra in the visible to near-infrared (400–1350 nm) were obtained using a field radiometer. The relations were evaluated using simple linear regression in combination with two spectral vegetation indices: the Difference Vegetation Index

L. Kooistra; E. A. L. Salas; J. G. P. W. Clevers; R. Wehrens; R. S. E. W. Leuven; P. H. Nienhuis; L. M. C. Buydens

2004-01-01

165

Effects of Salmon-Borne Nutrients on Riparian Soils and Vegetation in Southwest Alaska  

Microsoft Academic Search

Spawning Pacific salmon (Oncorhynchus spp.) contribute marine-derived nutrients to riparian ecosystems, potentially affecting characteristics of the associated soils and vegetation. We quantified these effects by comparing soil and vegetative characteristics upstream and downstream of natural migratory barriers on ten spawning streams in southwest Alaska. Mean ?15N values—indicative of salmon-borne nutrients—were significantly higher in the O horizon and surface mineral soils

Krista K. Bartz; Robert J. Naiman

2005-01-01

166

Influence of surface and vegetation characteristics on C-band radar measurements for soil moisture content  

Microsoft Academic Search

Soil moisture estimation using microwave remote sensing faces challenges of the segregation of influences mainly from roughness\\u000a and vegetation. Under static surface conditions, it was found that Radarsat C-band SAR shows reasonably good correlation and\\u000a sensitivity with changing soil moisture. Dynamic surface and vegetation conditions are supposed to result in a substantial\\u000a reduction in radar sensitivity to soil moisture. A

Shakil Ahmad Romshoo; Masahiro Koike; Sadayukihir Onaka; Taikan Oki; Katumi Musiake

2002-01-01

167

Vegetation Dynamics and Soil Water Balance Interactions in a Water-limited Mediterranean Ecosystem on Sardinia Under Climate Change Scenarios  

NASA Astrophysics Data System (ADS)

Mediterranean ecosystems are commonly heterogeneous savanna-like ecosystems, with contrasting plant functional types (PFT) competing for the water use. At the same time the structure and function of the vegetation regulates the exchange of mass, energy and momentum across the biosphere-atmosphere interface, influencing strongly the soil water budget. Mediterranean regions suffer water scarcity produced in part by natural (e.g., climate variations) influences. For instance, in the Flumendosa basin water reservoir system, which plays a primary role in the water supply for much of southern Sardinia, the average annual input from stream discharge in the latter part of the 20th century was less than half the historic average rate. The precipitation over the Flumendosa basin has decreased, but not at such a drastic rate as the discharge, suggesting a marked non-linear response of discharge to precipitation changes. Indeed, precipitation decreased in winter months, which are crucial for reservoirs recharge through runoff. The IPCC models predicts a further increase of drought in the Mediterranean region, increasing the uncertainty on the future of the water resources system of these regions. Hence, there is the need to investigate the role of the PFT vegetation dynamics on the soil water budget of these ecosystems in the context of the climate change, and predict hydrologic variables for climate change scenarios. The case study is in the Flumendosa basin. The site landscape is a mixture of Mediterranean patchy vegetation types: trees, including wild olives and cork oaks, different shrubs and herbaceous species. An extensive field campaign started in May 2003. Six years of data are available now. Land-surface fluxes and CO2 fluxes are estimated by an eddy correlation technique based micrometeorological tower. Soil moisture profiles were also continuously estimated using water content reflectometers and gravimetric method, and periodically leaf area index (LAI) PFTs are estimated. An ecohydrologic model is successfully tested to the case study. It couples a vegetation dynamic model (VDM), which computes the change in biomass over time for the PFTs, and a 3-component (bare soil, grass and woody vegetation) land surface model (LSM). Hydrometeorological change scenarios are then generated using a stochastic weather generator. It simulates hydrometeorological variables from historical time series (available from 1922 for this basin) altered by IPCC meteorological change predictions. The calibrated VDM-LSM predicts soil water balance and vegetation dynamics for the generated hydrometeorological scenarios. Results demonstrate that vegetation dynamics are strongly influenced by the variability of atmospheric forcing, with vegetation density changing significantly according to seasonal rainfall amount. At the same time the vegetation dynamics affect the soil water balance, and the runoff. Water resources predictions are worrying, with further decrease of runoff.

Montaldo, N.; Albertson, J. D.

2009-12-01

168

Soil Water Balance and Vegetation Dynamics in a Water-limited Mediterranean Ecosystem on Sardinia under climate change scenarios  

NASA Astrophysics Data System (ADS)

Mediterranean ecosystems are commonly heterogeneous savanna-like ecosystems, with contrasting plant functional types (PFT) competing for the water use. At the same time the structure and function of the vegetation regulates the exchange of mass, energy and momentum across the biosphere-atmosphere interface, influencing strongly the soil water budget. Mediterranean regions suffer water scarcity produced in part by natural (e.g., climate variations) influences. For instance, in the Flumendosa basin water reservoir system, which plays a primary role in the water supply for much of southern Sardinia, the average annual input from stream discharge in the latter part of the 20th century was less than half the historic average rate. The precipitation over the Flumendosa basin has decreased, but not at such a drastic rate as the discharge, suggesting a marked non-linear response of discharge to precipitation changes. Indeed, precipitation decreased in winter months, which are crucial for reservoirs recharge through runoff. The IPCC models predicts a further increase of drought in the Mediterranean region, increasing the uncertainty on the future of the water resources system of these regions. Hence, there is the need to investigate the role of the PFT vegetation dynamics on the soil water budget of these ecosystems in the context of the climate change, and predict hydrologic variables for climate change scenarios. The case study is in the Flumendosa basin. The site landscape is a mixture of Mediterranean patchy vegetation types: trees, including wild olives and cork oaks, different shrubs and herbaceous species. An extensive field campaign started in May 2003. More than six years of data of a micrometeorological tower are available now. Land-surface fluxes and CO2 fluxes are estimated by the eddy correlation technique based micrometeorological tower. Soil moisture profiles were also continuously estimated using water content reflectometers and gravimetric method, and periodically leaf area index (LAI) PFTs are estimated. An ecohydrologic model is successfully tested to the case study. It couples a vegetation dynamic model (VDM), which computes the change in biomass over time for the PFTs, and a 3-component (bare soil, grass and woody vegetation) land surface model (LSM). Hydrometeorological change scenarios are then generated using a stochastic weather generator. It simulates hydrometeorological variables from historical time series (available from 1922 for this basin) altered by IPCC meteorological change predictions. The calibrated VDM-LSM predicts soil water balance and vegetation dynamics for the generated hydrometeorological scenarios. Results demonstrate that vegetation dynamics are strongly influenced by the variability of atmospheric forcing, with vegetation density changing significantly according to seasonal rainfall amount. At the same time the vegetation dynamics affect the soil water balance, and the runoff. Water resources predictions are worrying, with further decrease of runoff.

Montaldo, Nicola; Cortis, Clorinda; Albertson, John D.

2010-05-01

169

Impact of vegetation and soil moisture seasonal dynamics on dust emissions over the Sahel  

NASA Astrophysics Data System (ADS)

To address the challenging issue of estimating mineral dust emissions from the semi-arid Sahel, a modeling approach is developed by combining two specific models: one dedicated to the simulation of the seasonal herbaceous layer in the Sahel (STEP) and the other to the estimation of dust emissions (MB). The area of interest is the Sahelian belt (12°N-20°N, 20°W-35°E) and the simulations were performed at a 0.25° spatial resolution over a 4-year period (2004-2007). The rainfall forcing is provided by a TRMM (Tropical Rainfall Measuring Mission) satellite-derived product; the other meteorological data are ECMWF products. An empirical parameterization is used to estimate the surface roughness and its temporal dynamics according to the characteristics of the simulated vegetation in terms of surface cover and height. Where no vegetation grows, the surface properties are considered as constant in time and are derived from the POLDER-1 satellite measurements. Simulations are constrained step by step by comparisons with observations. Simulated annual dust fluxes emitted from the whole area range from approximately 100 Mt to 400 Mt depending on the year, in good agreement with previous works dealing with Saharan dust emissions. For the fringe where herbaceous vegetation can affect dust emissions, the annual dust emission fluxes range between 0.5 Mt and 20 Mt depending on the year. Inhibition of dust emissions due to the seasonal dynamics of vegetation and surface soil moisture over this fringe varies between 20% and 35%.

Pierre, C.; Bergametti, G.; Marticorena, B.; Mougin, E.; Bouet, C.; Schmechtig, C.

2012-03-01

170

Why confining to vegetation indices? Exploiting the potential of improved spectral observations using radiative transfer models  

NASA Astrophysics Data System (ADS)

Vegetation indices (VI) combine mathematically a few selected spectral bands to minimize undesired effects of soil background, illumination conditions and atmospheric perturbations. In this way, the relation to vegetation biophysical variables is enhanced. Albeit numerous experiments found close relationships between vegetation indices and several important vegetation biophysical variables, well known shortcomings and drawbacks remain. Important limitations of VIs are illustrated and discussed in this paper. As most of the limitations can be overcome using physically-based radiative transfer models (RTM), advantages and limits of RTM are also presented.

Atzberger, Clement; Richter, Katja; Vuolo, Francesco; Darvishzadeh, Roshanak; Schlerf, Martin

2011-10-01

171

Thermal vegetation canopy model studies  

SciTech Connect

An iterative-type thermal model applicable to forest canopies was tested with data from two diverse forest types. The model framework consists of a system of steady-state energy budget equations describing the interactions of short- and long-wave radiation within three horizontally infinite canopy layers. A state-space formulation of the energy dynamics within the canopy is used which permits a factorization of canopy geometrical parameters from canopy optical and thermal coefficients as well as environmental driving variables. Two sets of data characterizing a coniferous (Douglas-fir) and deciduous (oak-hickory) canopy were collected to evaluate the thermal model. The results show that the model approximates measured mean canopy temperatures to within 2/sup 0/C for relatively clear weather conditions and deviates by a maximum of 3/sup 0/C for very hazy or foggy conditions.

Smith, J.A. (Colorado State Univ., Fort Collins); Ranson, K.J.; Nguyen, D.; Balick, L.; Link, L.E.; Fritschen, L.; Hutchison, B.

1981-01-01

172

Coupling of snow distribution, soil moisture, and vegetation on two subalpine hillslopes  

NASA Astrophysics Data System (ADS)

Subalpine forests are subject to extreme gradients in temperature and soil moisture. This study explores how dynamics of snowmelt and soil moisture relate to tree distribution on two subalpine hillslopes in the Loch Vale watershed in Rocky Mountain National Park, USA. The hillslopes are at approximately 3200 m elevation with 30% average slope. Near tree-line, the hillslopes have a patchy distribution of trees, with Engelmann spruce and subalpine fir covering only about 50% of the hillslope surface area. To determine how forest patch characteristics relate to hydrologic dynamics in these hillslopes, we set up two-hundred meter transects, each extending from a bedrock cliff face upslope to a stream downslope. One transect has a northeast-facing aspect, and the other has a southeast-facing aspect. During summer 2008, we collected weekly or bi-weekly measurements of snow depth, surface soil moisture, and surface soil temperature at 10 m increments along these transects. Under seasonal snow cover, the hillslopes were not completely snow- free until mid July. Snow distribution was highly variable along the hillslopes, with snow persisting longest in clearings between forest patches. Except during the days immediately following snow melt, hillslope soil moisture distributions were uncorrelated with snow distribution and instead reflected localized downslope subsurface flow paths. Trees cluster in segments of the hillslope with the lowest slope gradients, and the largest trees in both hillslopes were located mid-slope, just below steep slope breaks. Although surface soil moisture was consistently higher on the northeast-facing hillslope, trees are on average larger on the southeast-facing slope, which has warmer average temperatures and deeper soils. Results suggest a complex coupling between tree distribution and snowmelt runoff in this transitional environment, and future work will continue to explore these feedbacks by combining more detailed vegetation and soil depth characterization with soil water chemistry and subsurface flow modeling.

Kampf, S. K.; Markus, J.

2008-12-01

173

Influence of Near-Surface Vegetation on the Values and Variability of Soil Water Content  

Microsoft Academic Search

Shallowly rooted vegetation can have a significant influence on the water content of near-surface soils. In precision agriculture applications, shallowly rooted crop cover is often used to modify the natural soil water content to produce optimal moisture conditions for the primary crop. In this study, the influence of crop cover on shallow soil moisture at a 3-acre California vineyard with

K. R. Grote

2003-01-01

174

Insecticide residues in organic soils of six vegetable growing areas in Southwestern Ontario, 1976  

Microsoft Academic Search

Organic soils on 28 farms located in six widely separated vegetable growing areas in southwestern Ontario were sampled in 197 6 and analyzed for insecticide residues. Soil organic content generally was >65%. Organochlorine insecticide residues were detected in soil on all farms. Total DDT ranged from <0.1 to 29 ppm. Dieldrin, endo?sulfan, and endrin were present at levels up to

J. R. W. Miles; C. R. Harris

1978-01-01

175

Response of labile soil organic matter to changes in forest vegetation in subtropical regions  

Microsoft Academic Search

Labile soil organic matter (SOM) can sensitively respond to changes in land use and management practices, and has been suggested as an early and sensitive indicator of SOM. However, knowledge of effects of forest vegetation type on labile SOM is still scarce, particularly in subtropical regions. Soil microbial biomass C and N, water-soluble soil organic C and N, and light

Qingkui Wang; Silong Wang

2011-01-01

176

SOIL MOISTURE EXPERIMENTS 2004 AND 2005 FOR EVALUATION OF VEGETATION WATER CONTENT WITH MODIS  

Technology Transfer Automated Retrieval System (TEKTRAN)

The Soil Moisture Experiment 2004 (SMEX04) and Soil Moisture Experiment 2005 (SMEX05) were conducted to test algorithms in support of Aqua AMSR-E and the future HYDROS mission. Vegetation Water Content is a major uncertainty for retrieval of soil moisture from microwave data, and MODIS shortwave in...

177

Evaluation of MODIS NDVI and NDWI for vegetation drought monitoring using Oklahoma Mesonet soil moisture data  

USGS Publications Warehouse

The evaluation of the relationship between satellite-derived vegetation indices (normalized difference vegetation index and normalized difference water index) and soil moisture improves our understanding of how these indices respond to soil moisture fluctuations. Soil moisture deficits are ultimately tied to drought stress on plants. The diverse terrain and climate of Oklahoma, the extensive soil moisture network of the Oklahoma Mesonet, and satellite-derived indices from the Moderate Resolution Imaging Spectroradiometer (MODIS) provided an opportunity to study correlations between soil moisture and vegetation indices over the 2002-2006 growing seasons. Results showed that the correlation between both indices and the fractional water index (FWI) was highly dependent on land cover heterogeneity and soil type. Sites surrounded by relatively homogeneous vegetation cover with silt loam soils had the highest correlation between the FWI and both vegetation-related indices (r???0.73), while sites with heterogeneous vegetation cover and loam soils had the lowest correlation (r???0.22). Copyright 2008 by the American Geophysical Union.

Gu, Y.; Hunt, E.; Wardlow, B.; Basara, J. B.; Brown, J. F.; Verdin, J. P.

2008-01-01

178

The influence of variations of vegetation and soil moisture on surface weather and atmospheric circulation  

SciTech Connect

The influence of variations of vegetation and soil moisture on surface weather and atmospheric circulation is studied through the use of the Simple Biosphere Model (SiB) and the Center for Ocean-Land-Atmosphere interactions (COLA) GCM. Tests for the SiB sensitivity to the conversion of the forest to other short vegetation or bare soil were performed at Amazonian and Great Plains sites, and a North Wales spruce forest site respectively. The results show that deforestation has a significant influence on the local surface energy budget and surface weather. The influence is especially prominent at the Amazon and Great Plains sites, and larger in summer than in other seasons. The influence on the partitioning of surface incoming radiative energy is generally constrained by the local atmospheric boundary condition. The sensitivity of the COLA GCM to changes in initial soil wetness (ISW) is determined by repeating three 10-day model integrations with the same initial and boundary conditions as the control runs except the values of ISW, which are revised at 69 model grid points covering much of the continental U.S. It is found that the relations between the changes in the 5-day mean forecast surface air temperature/surface specific humidity and the changes in ISW depend upon vegetation type and the values of ISW, and can be approximated by regression equations. These relations are also confirmed with independent data. With the ISW revised based on these regression equations the surface forecasts of the revised runs are consistently improved. The spatial scale of the ISW anomaly determines the degree and range of the influence. The influence of a small regional ISW change is mainly confined to the local region and to low atmospheric levels. The influence on surface fluxes is strong and persists for more than one month, but the effects on precipitation are relatively weak, changeable, and complex, particularly when an interactive cloud scheme is used.

Yang, R.

1992-01-01

179

THE LONG-TERM VEGETABLE PRODUCTION EXPERIMENT: PLANT GROWTH AND SOIL FERTILITY COMPARISONS BETWEEN FERTILIZER AND COMPOST-AMENDED SOILS  

Microsoft Academic Search

A paired comparative study of compost versus conventionally-fertilized vegetable plots has been conducted for 11 years in a sandy loam soil near Truro, Nova Scotia; likely the longest study of its kind in Canada. The fertility treatments have been applied annually to six rotation plots planted with six to eight different vegetable crops. Compost and fertilizer applications have been based

P. R. Warman

180

Synergistic effect of vegetation and air temperature changes on soil water content in alpine frost meadow soil in the permafrost region of Qinghai-Tibet  

Microsoft Academic Search

Seasonal changes over 2 years (2004-2006) in soil moisture content (? v) of frozen alpine frost meadow soils of the Qinghai- Tibet plateau permafrost region under three different levels of vegetation cover were investigated. Vegetation cover and air temperature changes had significant effects (synergistic effect) onv and its distribution in the soil profile. During periods of soil freezing or thawing,

Genxu Wang; Yuanshou Li; Hongchang Hu; Yibo Wang

2008-01-01

181

Calculation set for design and optimization of vegetative soil covers Sandia National Laboratories, Albuquerque, New Mexico.  

SciTech Connect

This study demonstrates that containment of municipal and hazardous waste in arid and semiarid environments can be accomplished effectively without traditional, synthetic materials and complex, multi-layer systems. This research demonstrates that closure covers combining layers of natural soil, native plant species, and climatic conditions to form a sustainable, functioning ecosystem will meet the technical equivalency criteria prescribed by the U. S. Environmental Protection Agency. In this study, percolation through a natural analogue and an engineered cover is simulated using the one-dimensional, numerical code UNSAT-H. UNSAT-H is a Richards. equation-based model that simulates soil water infiltration, unsaturated flow, redistribution, evaporation, plant transpiration, and deep percolation. This study incorporates conservative, site-specific soil hydraulic and vegetation parameters. Historical meteorological data are used to simulate percolation through the natural analogue and an engineered cover, with and without vegetation. This study indicates that a 3-foot (ft) cover in arid and semiarid environments is the minimum design thickness necessary to meet the U. S. Environmental Protection Agency-prescribed technical equivalency criteria of 31.5 millimeters/year and 1 x 10{sup -7} centimeters/second for net annual percolation and average flux, respectively. Increasing cover thickness to 4 or 5 ft results in limited additional improvement in cover performance.

Peace, Gerald L.; Goering, Timothy James (GRAM, Inc., Albuquerque, NM)

2005-02-01

182

Does vegetation solve the problem of modelling the 'equable' Early Eocene climate?  

NASA Astrophysics Data System (ADS)

The Early Eocene (55-50 Million years ago) ranks among the warmest period in the Cenozoic (past 65 Million years) with a global mean temperature higher than modern and with ice-free poles. Warm climates as the Early Eocene are characterised by a pole-to-equator temperature gradient and a seasonality in the mid and high latitudes lower than present day. Modelling these features still remains challenging. In many studies, the simulated annual global mean temperature for the Early Eocene agrees with proxy data. However, the climate at the poles remains too cold and the seasonality is too strong in the models. In order to investigate the impact of the terrestrial biosphere on the 'equable' Early Eocene climate, we perform four model simulations with MPI-ESM including dynamic vegetation. In all simulations, the same Early Eocene boundary conditions are chosen except for different globally homogeneous soil albedo values and vegetation cover. Two simulations are run with desert conditions and low (0.1) and high (0.4) soil albedo, respectively, and another two simulations with continents completely covered by forests and low and high soil albedo, respectively. The dark desert world is the warmest of all simulations. Sea ice is absent in this case and some snow occurs in winter only. The simulations with trees are cooler than the dark desert simulation, and the bright desert simulation is the coolest. In the bright desert world, even sea ice occurs seasonally. These results suggest that vegetation cools Early Eocene climate in the dark soil case and warms it in the bright soil case. The driving mechanisms for the cooling by vegetation in the dark soil case are associated with changes in the water cycle. The cooling initiated by vegetation is amplified in the high latitudes as the snow cover increases in winter leading to a surface albedo increase. In the bright soil case, vegetation lowers the surface albedo efficiently and leads to a warming. This warming causes the seasonal sea ice cover to vanish and the snow cover to decrease. The resulting albedo feedback amplifies the warming in the high latitudes. After 400 years of simulation, we let the vegetation cover develop dynamically. In all simulations, the vegetation cover evolves nearly to the same equilibrium. However, regional multiple equilibria occur. The resulting vegetation distribution matches vegetation reconstructions for the Early Eocene well. In a subsequent step, the plant functional types used in the model are adapted to nearest living relatives of the Early Eocene vegetation.

Port, Ulrike; Claussen, Martin

2013-04-01

183

Impact of vegetation change on the mobility of uranium- and thorium-series nuclides in soils  

NASA Astrophysics Data System (ADS)

The effect of land cover change on chemical mobility and soil response was investigated using short- and long-lived nuclides from the U- and Th series. Indeed, the matching of these nuclides half-live to the pedogenic processes rates make these nuclides especially suitable to investigate either time or mechanism of transfers within a soil-water-plant system. This study was carried out from the experimental Breuil-Chenue site (Morvan mountains, France). The native forest (150 year-old) was partially clear-felled and replaced in 1976 by mono-specific plantations distributed in different stands. Following this cover-change, some mineralogical changes in the acid brown soil were recognized (Mareschal, 2008). Three soil sections were sampled under the native forest and the replanted oak and Douglas spruce stands respectively. The (238U), (234U), (230Th), (226Ra), (232Th) and (228Ra) activities were analysed by thermal ionization mass spectrometry (TIMS), inductively coupled plasma mass spectrometry (MC-ICPMS) and gamma spectrometry. Significant differences in U, Th, and Ra activities were observed between the soils located under the native forest or the replanted-trees stands, mostly dominated by a large uranium mobilization from the replanted soils. Moreover, all the investigated U and Th-series activity ratios show a contrasted trend between the shallowest horizons (0-50cm) and the deepest one (below 50cm), demonstrating the chemical effect of the vegetation change on the shallow soil layers. Using a continuous open-system leaching model, the coupled radioactive disequilibria measured in the different soil layers permit to quantify the rate of the radionuclides mobilities. Reference: Mareschal, L., 2008. Effet des substitutions d'essences forestières sur l'évolution des sols et de leur minéralogie : bilan après 28 ans dans le site expérimental de Breuil (Morvan) Université Henri Poincaré, Nancy-I.

Gontier, A.; Rihs, S.; Turpault, M.-P.; Chabaux, F.

2012-04-01

184

Phytoavailability of thallium - A model soil experiment  

NASA Astrophysics Data System (ADS)

The study deals with the environmental stability of Tl-modified phases (ferrihydrite, goethite, birnessite, calcite and illite) and phytoavailability of Tl in synthetically prepared soils used in a model vegetation experiment. The obtained data clearly demonstrate a strong relationship between the mineralogical position of Tl in the model soil and its uptake by the plant (Sinapis alba L.). The maximum rate of Tl uptake was observed for plants grown on soil containing Tl-modified illite. In contrast, soil enriched in Ksat-birnessite had the lowest potential for Tl release and phytoaccumulation. Root-induced dissolution of synthetic calcite and ferrihydrite in the rhizosphere followed by Tl mobilization was detected. Highly crystalline goethite was more stable in the rhizosphere, compared to ferrihydrite, leading to reduced biological uptake of Tl. Based on the results, the mineralogical aspect must be taken into account prior to general environmental recommendations in areas affected by Tl.

Vanek, Ales; Mihaljevic, Martin; Galuskova, Ivana; Komarek, Michael

2013-04-01

185

Relations between Root-zone Soil Moisture and MODIS-derived Vegetation Indices in Oak savanna and Open Grassland in California  

NASA Astrophysics Data System (ADS)

Optical remote sensing cannot provide direct quantification of soil moisture, but here we test the idea that plant available soil moisture can be inferred through calibration of images that quantify plant-leaf water and photosynthetic relationships. We measured relationships between volumetric soil water content in the rooting zone of annual grasslands and oak savanna and six vegetation indices (VIs) derived from MODIS data (NDVI, EVI, ARVI, SAVI,VARI and NDWI). The measured sites were part of the AmeriFlux network in California: Tonzi Ranch (oak savanna)and Vaira Ranch(open grassland). To reduce the empirical effect of linking vegetation indices to soil moisture directly, measured gross primary production (GPP) was used to bridge them. The results showed that (1) VARI was most sensitive to soil moisture variations; (2) in open grassland GPP is significantly controlled by the available water in the soil but the relationship is not linear----- GPP continues to increase in the growing season as long as soil moisture is sufficient. In oak savanna, the relationship is less obvious because oak trees can exploit water in deep soil layers. The results also demonstrated a strong linear relationship between GPP and vegetation indices for both oak savanna and open grassland. Therefore, based on the relation between GPP and root-zone soil moisture and the relation between GPP and VI, we estimated soil moisture as a function of a VI. Likely, the functional parameters are dependent on vegetation types, soil texture and topography. In order to explore the sensitivity of this relationship in areas where soil moisture and vegetation production data are not available, we will use DayCENTURY and ISOLSM models to simulate soil moisture and primary production at instrumented sites with meteorological data and soil properties data. The simulation tested in Tonzi Ranch and Vaira Ranch suggest that we can estimate root-zone soil moisture with optical remotely sensed data at large scale.

Liu, S.; Chadwick, O.; Roberts, D.

2008-12-01

186

Transregional Collaborative Research Centre 32: Patterns in Soil-Vegetation-Atmosphere-Systems  

NASA Astrophysics Data System (ADS)

The soil-vegetation-atmosphere system is characterized by non-linear exchanges of mass, momentum and energy with complex patterns, structures and processes that act at different temporal and spatial scales. Under the TR32 framework, the characterisation of these structures and patterns will lead to a deeper qualitative and quantitative understanding of the SVA system, and ultimately to better predictions of the SVA state. Research in TR32 is based on three methodological pillars: Monitoring, Modelling and Data Assimilation. Focusing our research on the Rur Catchment (Germany), patterns are monitored since 2006 continuously using existing and novel geophysical and remote sensing techniques from the local to the catchment scale based on ground penetrating radar methods, induced polarization, radiomagnetotellurics, electrical resistivity tomography, boundary layer scintillometry, lidar techniques, cosmic-ray, microwave radiometry, and precipitation radars with polarization diversity. Modelling approaches involve development of scaled consistent coupled model platform: high resolution numerical weather prediction (NWP; 400m) and hydrological models (few meters). In the second phase (2011-2014), the focus is on the integration of models from the groundwater to the atmosphere for both the m- and km-scale and the extension of the experimental monitoring in respect to vegetation. The coupled modelling platform is based on the atmospheric model COSMO, the land surface model CLM and the hydrological model ParFlow. A scale consistent two-way coupling is performed using the external OASIS coupler. Example work includes the transfer of laboratory methods to the field; the measurements of patterns of soil-carbon, evapotranspiration and respiration measured in the field; catchment-scale modeling of exchange processes and the setup of an atmospheric boundary layer monitoring network. These modern and predominantly non-invasive measurement techniques are exploited in combination with advanced modelling systems by data assimilation to yield improved numerical models for the prediction of water-, energy and CO2-transfer by accounting for the patterns occurring at various scales.

Masbou, M.; Simmer, C.; Kollet, S.; Boessenkool, K.; Crewell, S.; Diekkrüger, B.; Huber, K.; Klitzsch, N.; Koyama, C.; Vereecken, H.

2012-04-01

187

Effect of vegetation change from native broadleaf forest to coniferous plantation on selected soil properties.  

PubMed

The objective of this study was to examine the effects of vegetation change from a native broadleaf forest to a coniferous plantation on selected soil properties, including soil texture, pH, organic matter, total nitrogen (N), total phosphorus (P), exchangeable cations (Ca(2+), K(+), Na(+)), and cation exchange capacity (CEC). Results showed that the amount of clay particles, Ca(2+), and K(+) values significantly increased, whereas Na(+), total N, and organic matter and soil pH values decreased on the treatment plot after vegetation change. Soil acidity also increased and soil textural group changed from moderately fine-textured soils (clay loam) to medium-textured soils (loam) under both control and treatment plots. Organic matter, total N, and Na(+) values increased, whereas Ca(2+) concentration decreased through time on the control plot. Soil pH, total P, K(+), and CEC did not show significant changes through time on the control plot. PMID:23832186

H?zal, Ahmet; Gökbulak, Ferhat; Zengin, Mustafa; Ercan, Mehmet; Karaka?, Ahmet; Tu?rul, Dilek

2013-07-06

188

Terrestrial vegetation and water balance—hydrological evaluation of a dynamic global vegetation model  

Microsoft Academic Search

Earth's vegetation plays a pivotal role in the global water balance. Hence, there is a need to model dynamic interactions and feedbacks between the terrestrial biosphere and the water cycle. Here, the hydrological performance of the Lund–Potsdam–Jena model (LPJ), a prominent dynamic global vegetation model, is evaluated. Models of this type simulate the coupled terrestrial carbon and water cycle, thus

Dieter Gerten; Sibyll Schaphoff; Uwe Haberlandt; Wolfgang Lucht; Stephen Sitch

2004-01-01

189

Estimating Fractional Cover of Photosynthetic Vegetation, Non-Photosynthetic Vegetation and Soil in Savannas Using the EO-1 Hyperion and MODIS Sensors  

NASA Astrophysics Data System (ADS)

Monitoring the fractional cover of photosynthetic vegetation (PV), non-photosynthetic vegetation (NPV) and bare soil (BS) in savannas is important for carbon and water modeling, grazing management, fire risk assessment and erosion control. We developed a simple method for resolving their fractional cover with hyperspectral imagery, by combining the Normalized Difference Vegetation Index (NDVI) which measures vegetation greenness and the Cellulose Absorption Index (CAI), which quantifies the intensity of the cellulose-lignin feature at 2.0-2.2 ?m, and then applying a linear unmixing. We applied this method to three EO-1 Hyperion scenes acquired during the 2005 growing season in a site in northern Australia. Data from field measurements and from fire scar maps provided a means for qualitatively validating the results obtained. We then explored the potential of the MODIS-TERRA sensor for resolving vegetation fractional cover. We generated synthetic MODIS data from the Hyperion images and also used actual MODIS reflectance from the MOD09 product, concurrent with the Hyperion images. We found that the MODIS-TERRA sensor, despite not being able to quantify the cellulose feature directly, can be used for mapping fractional cover. This is due to the fact that vegetation, regardless of its photosynthetic status, has a lower reflectance at 2.1 ?m (MODIS band 7) than at 1.6 ?m (MODIS band 6), compared to soils, which have a relatively flat spectra at those wavelengths. We propose using the ratio of band 7 to band 6 together with the NDVI for resolving the proportions of PV, NPV and BS. We tested the method in 10 independent savanna sites across Australia where grass curing is continuously monitored and found very good agreement both in space and in time between observed and modeled fractional cover. Finally, we developed a prototype of an operational product based on the MOD43 product (Nadir BRDF-Adjusted Reflectance 16-Day composites) and discuss its strengths and limitations.

Guerschman, J. P.; Hill, M. J.; Barrett, D. J.; Renzullo, L.; Marks, A.; Botha, E.

2007-12-01

190

Improving Thermal IR Sensor-Derived Soil Moisture Mapping of the Walnut Gulch Experimental Watershed, SE Arizona using Soil Texture and Vegetation Data  

NASA Astrophysics Data System (ADS)

Soil moisture studies, especially those in semi-arid environments, are critical in understanding weather, climate, agricultural productivity, society impact, and national security. However, studying this type of environment is often difficult and costly due to remote locations, rapid dry-down following precipitation events, and required specialized equipment. In order to overcome these obstacles, remotely sensed data has been employed with limited success, as these measurements are at coarse spatial resolutions on the order of 10 km or more [e.g, 1]. Recent approaches of retrieving soil moisture have shown promise by utilizing the sensor-derived apparent thermal inertia (ATI) of the surface from higher spatial resolution imagers, including the Moderate Resolution Imaging Spectroradiometer (MODIS; 1 km) and the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER; 90 m) [e.g, 2]. We attempt to improve the ATI algorithm by analyzing comparisons between the sensor-derived values and in-situ field data from the Walnut Gulch Experimental Watershed (WGEW) in southeastern Arizona. Modeled soil moisture was derived from a 10-year time series of archival MODIS data and 2 day/night acquisitions of ASTER data, accommodating for differences in scale. To accomplish this task: 1) high spatial resolution soil moisture maps were created, 2) the algorithm results were validated with an extensive open-source network of in-situ rain and 5 cm depth soil moisture gauge data, and 3) the soil moisture retrievals were adjusted for heterogeneous soils and vegetation cover. A proxy for soil texture is derived from associated mineral maps, produced by linear spectral deconvolution of emissivity [3 and 4] and validated by the open source WGEW soil maps. Vegetation influence is determined from VNIR data using standard band ratios. The results of this analysis will aim to improve the algorithm, and more accurately derive soil moisture by accounting for soil texture and vegetation. Future work will provide spectral ground truth of targeted areas using a handheld, portable FTIR spectrometer, accounting for the effects of atmospheric attenuation and vegetation type. These field activities will validate soil composition maps produced from ASTER TIR and improve proxy data for soil texture. The results of this study will not only provide high spatial resolution soil moisture maps for semi-arid environments, it will also show the importance of amalgamating multiple remote sensing techniques to solve problems occurring in similar environments worldwide. (1) Distribution Statement A -- Approved for public release; distribution is unlimited.

Rose, S.; Scheidt, S. P.; Tischler, M.

2011-12-01

191

Manipulation of Landsat Spectral Characteristics to Classify Vegetation and Soil Wetness in the Rainforest of Bolivia.  

National Technical Information Service (NTIS)

This study attempts to classify tropical region soils and vegetation by moisture content from multispectral imagery. Identified wet areas were used to determine the percentage of wetness in the study area, by evaluating the spectral response of tropical r...

M. G. Barwick H. B. Puffenberger

1992-01-01

192

Terrestrial Vegetation and Soils Monitoring at Fort Davis National Historic Site: Status Report.  

National Technical Information Service (NTIS)

This report summarizes results of the Chihuahuan Desert Networks first season of terrestrial vegetation and soils monitoring in upland areas of Fort Davis National Historic Site (NHS), on the southeastern edge of the Davis Mountains in Texas. Ten permanen...

C. L. McIntyre S. E. Studd

2013-01-01

193

Soil-Vegetation Correlations in the Sandhills and Rainwater Basin Wetlands of Nebraska,  

National Technical Information Service (NTIS)

As part of a national study, vegetation associated with known hydric and nonhydric soil series was sampled in selected wetlands in the Rainwater Basin and Sandhills regions of Nebraska. Weighted averages, presence/absence averages, and Michener averages w...

N. E. Erickson D. M. Leslie

1987-01-01

194

Cause of the Hot Spot in Vegetation Canopies and Soils: Shadow-Hiding Versus Coherent Backscatter.  

National Technical Information Service (NTIS)

Two different mechanisms, shadow-hiding and coherent backscatter, can cause a hot spot, or opposition effect, in the bidirectional reflectance of vegetation and soils. Because the two mechanisms sample different properties, it is important to know which o...

B. Hapke D. DiMucci R. Nelson W. Smythe

1996-01-01

195

Responses of Understory Vegetation on Highly Erosive Louisiana Soils to Prescribed Burning in May.  

National Technical Information Service (NTIS)

Prescribed burning is necessary to restore the herbaceous plant community normally associated with the fire-dependent longleaf pine, Pinus palustris Mill., ecosystem. The effects of a May burn on soil movement and vegetation growing on two hilltop glades ...

J. D. Haywood A. Martin J. C. Novosad

1995-01-01

196

[Survival of ascaris eggs, salmonella and fecal coli in soil and on vegetables grown in infected soil (author's transl)].  

PubMed

In an experiment it was shown that eggs of Ascaris suum, salmonella and fecal coliform bacteria mixed with sewage sludge and added to soil, will survive the first growing season. Most eggs of Ascaris suum in soil embryonated within a period of 7--15 weeks. In soil without a protective vegetation the concentration of eggs in the top soil layer 0--3 cm decreased faster than in soil with a protective vegetation. At the same time there seemed to be a corresponding increase in the concentration of eggs in the deeper layers of the soil. In the top layer, especially in the top soil without a protective vegetation, there was towards the end of the first growing season a higher per cent of dead eggs than in the deeper layers. The concentration of fecal coliform bacteria and salmonella was in the course of the first growing season reduced to 1/1000 and 1/10000, respectively, of the initial concentration. Infective Ascaris suum eggs and salmonella were found in washing water from vegetables grown in the first season. Infective Ascaris suum eggs were also present in soil in the second and third growing season. PMID:6261218

Bergstrøm, K; Langeland, G

1981-01-01

197

Effects of soil moisture variations on deposition velocities above vegetation.  

SciTech Connect

The parameterized subgrid-scale surface flux (PASS) model provides a simplified means of using remote sensing data from satellites and limited surface meteorological information to estimate the influence of soil moisture on bulk canopy stomatal resistances to the uptake of gases over extended areas. PASS-generated estimates of bulk canopy stomatal resistance were used in a dry deposition module to compute gas deposition velocities with a horizontal resolution of 200 m for approximately 5000 km{sup 2} of agricultural crops and rangeland. Results were compared with measurements of O{sub 3} flux and concentrations made during April and May 1997 at two surface stations and from an aircraft. The trend in simulated O{sub 3} deposition velocity during soil moisture drydown over a period of a few days matched the trend observed at the two surface stations. For areas under the aircraft flight paths, the variability in simulated O{sub 3} deposition velocity was substantially smaller than the observed variability, while the averages over tens of kilometers were usually in agreement within 0.1 cm s{sup -1}. Model results indicated that soil moisture can have a major role in deposition of O{sub 3} and other substances strongly affected by canopy stomatal resistance.

Wesely, M. L.; Song, J.; McMillen, R. T.; Meyers, T. P.; Environmental Research; Northern Illinois Univ.; National Oceanic and Atmospheric Administration

2001-01-01

198

Effect of slight vegetation degradation on soil properties in Brachypodium pinnatum grasslands  

Microsoft Academic Search

The interrelationship of soil and vegetation degradation is an emerging issue, where most studies have addressed severe degradation\\u000a so far. We aimed at revealing changes in soil accompanying slight vegetation degradation in a case study involving xeromesophilous\\u000a grasslands from Hungary. Slight degradation is of special interest here because the target community (Euphorbio pannonicae—Brachypodietum pinnati association) has great nature conservation value.

Klára Virágh; Tibor Tóth; Imelda Somodi

199

Influences of subsurface heterogeneity and vegetation cover on soil moisture, surface temperature and evapotranspiration at hillslope scales  

NASA Astrophysics Data System (ADS)

Physical processes are at the root of determining hydrologic response at all scales. Here, the physical mechanisms linking (1) subsurface heterogeneities to soil moisture and (2) resulting land-surface energy feedbacks to the atmosphere, are examined at the hillslope scale using a fully coupled surface-subsurface-land-surface model, ParFlow. A hillslope with a heterogeneous subsurface and uniform topography was modeled numerically using summer atmospheric conditions and a single precipitation event under controlled boundary conditions in order to isolate the contribution of hydraulic conductivity to land-surface hydrological processes and energy interactions. Patterns of subsurface hydraulic conductivity are shown to govern soil-moisture distribution at the hillslope scale following precipitation. This variability in soil moisture is closely linked to the variability in land-surface energy feedbacks. The role that vegetation plays in subsurface soil moisture and land energy communications is also examined. Results show that hillslope soil moisture variation is first established by patterns in vertical hydraulic conductivity, while later on in the dry-down period, vegetation exerts greater control on the land-surface energy fluxes and controls the rate of hillslope dry down. Furthermore, as compared to bare-soil simulations, grass-cover simulations show an increase in near-surface soil moisture despite water up-take along the rooting depth.

Atchley, Adam L.; Maxwell, Reed M.

2011-03-01

200

Analysis of soil organic carbon and vegetation cover trends along the Botswana Kalahari Transect  

Microsoft Academic Search

Determination of trends in soil organic carbon (SOC) and vegetation cover along savanna ecosystem moisture gradients is critical to the understanding of ecosystem functioning and global change. Field results from 57 sites along the Botswana Kalahari Transect (BKT) showed general increases in both SOC and vegetation cover components along the temperature\\/moisture gradient. However, details in both SOC and woody cover

Susan Ringrose; Wilma Matheson; Cornelis Vanderpost

1998-01-01

201

Storage of atmospheric carbon in global litter and soil pools in response to vegetation change and biomass allocation  

SciTech Connect

Changes in the distribution of vegetation types under altered climate regimes could have important consequences for the storage of stems. Because there are relatively few definitive field studies of changes in whole ecosystem carbon process-level models driven by gridded global databases may provide reasonable indicators of to changes in vegetation cover. We have used plant litter quality (lignin content) and carbon allocation to woody tissues as surrogates for testing the hypothetical effects of future vegetation change using the CASA (Carnegie-Ames-Stanford Approach) Biosphere model. The model is driven by global gridded (1{degree}) satellite imagery on a monthly time interval to simulate seasonal patterns in net ecosystem carbon balance and steady-state carbon storage in detritus arid soils. Sensitivity tests treated litter quality and allocation effects independently from other direct effects of changes in climate, atmospheric CO{sub 2} levels, and primary production. Results support the hypothesis that soil C storage in today`s temperate and boreal forest life zones are those most sensitive to changes in litter lignin content which may accompany increased climate stress. For these systems, the model predicts that a 50% increase in litter lignin concentration would result in a long-term net gain of about 10% C from the atmosphere into surface litter and soil organic matter pools. A 50% decrease in C allocation to woody tissues would invoke a net loss of 10% C from litter and soil organic matter pools.

Klooster, S.A.; Potter, C.S. [NASA/Ames Research Center, Moffett Field, CA (United States)

1995-06-01

202

Spatial heterogeneity of soil properties and vegetation–soil relationships following vegetation restoration of mobile dunes in Horqin Sandy Land, Northern China  

Microsoft Academic Search

Quantitative methods were used to examine soil properties and their spatial heterogeneity in a 0-year fenced mobile dune (MD0),\\u000a an 11-year fenced mobile dune (MD11) and a 20-year fenced mobile dune (MD20) in Horqin Sandy Land, Northern China. The objective\\u000a of the study was to assess the effect of vegetation restoration on heterogeneity of soil properties in sand dunes and

Xiaoan Zuo; Xueyong Zhao; Halin Zhao; Tonghui Zhang; Yirui Guo; Yuqiang Li; Yingxin Huang

2009-01-01

203

A method to estimate the concentration of elements in smoke from burning vegetation growing in contaminated soil  

Microsoft Academic Search

The Savannah River Site has areas where soil is contaminated with metals and\\/or radionuclides. Many of these areas are surrounded by native vegetation which is growing adjacent to the area and where the roots have penetrated into the contaminated soil of the area. In some cases vegetation has actually invaded the contaminated area. Even though the volume of contaminated vegetation

C. E. Jr

2010-01-01

204

A method to estimate the concentration of elements in smoke from burning vegetation growing in contaminated soil  

Microsoft Academic Search

The Savannah River Site has areas where soil is contaminated with metals and\\/or radionuclides. Many of these areas are surrounded by native vegetation which is growing adjacent to the area and where the roots have penetrated into the contaminated soil of the area. In some cases vegetation has actually invaded the contaminated area. Even though the volume of contaminated vegetation

C. E. Jr

1991-01-01

205

Simulation of vegetation, soil characteristics, and topography effects on soil water distribution and streamflow timing over a semi-arid mountain catchment  

NASA Astrophysics Data System (ADS)

Soil water (? , m3m-3) and soil characteristics act as intermediaries, along with plants and climate, modifying and modulating streamflow timing and quantity-the majority in the intermountain US west resulting from spring-melt events of accumulated winter snow. The antecedent soil water conditions also predispose different patterns and dynamic responses, especially in semiarid, mountain regions. The context of soil water, analyzed using modeling, is necessary to describe the processes of soil water dynamics. In this research, two years of neutron probe soil water data from a small, semiarid mountain catchment were evaluated using a vertical flow, combined snowmelt-soil water, capacitance-parameter model with available snowmelt data and climate data as driving inputs. Model parameters were vegetation characteristics and soil properties. Results at the point scale show good fit at many locations while a few have poor simulation results at depth. The discrepancies are hypothesized to be due to lack of understanding of parameters such as rooting depth of trees; heterogeneity of parameters within the soil layers; using capacitance parameters that treat some variables as constants; exclusion of lateral flow processes that must occur in some locations due to basin geometry and nature of soil-fractured bedrock interface; and rising water table effects that can be seen in the gleying of clayey soils near drainage lines. Driving parameters were then distributed over the 0.36 km2 catchment using the regional 10 m DEM, soil maps, remotely sensed color-infrared imagery, and the spatiotemporal distributions of soil water from previous research. The model was run discretely at each pixel. Results matched point data simulations well. Simulated throughflow, totaled over the watershed, compared well with weir measured streamflow in timing and quantity indicating accurate representation of parameters over the watershed, proper calibration, and well described processes.

Grant, L. E.; Seyfried, M. S.; Marks, D.; Winstral, A.

2004-12-01

206

Soil vulnerability to future climate in the southwestern USA, with implications for vegetation change and water cycle  

NASA Astrophysics Data System (ADS)

Understanding soil response to changes in precipitation/snow cover and increasing temperatures is essential to predicting changes in riparian, wetland, and aquatic as well as terrestrial communities in the coming decades. Changes in precipitation and snowmelt are affecting streamflow seasonality and magnitude, and rising air temperatures and declining precipitation affect aquatic habitats directly by causing increases in stream temperatures and evapo-transpiration causing lower streamflow. The water resources of the Colorado River system are projected to be strained due to runoff losses of 7 to 20% this century, and a reduction of approximately 5% of the annual average runoff is due to increased evapotranspiration from early exposure of vegetation and soils. We are developing a spatially-explicit soil vulnerability index of high, moderate and low sensitivity soils for the southwestern USA and comparing it to projections of vegetation dieback under future climate change scenarios to provide 1) a measure of uncertainty of the model skill and 2) a warning that vegetation shifts may increase soil vulnerability in areas where it is still protected by current plant cover, thus enabling a preliminary estimate of the future location of sources of aeolian dust.

Peterman, W. L.; Bachelet, D. M.

2011-12-01

207

Modelling increased soil cohesion by plant roots with EUROSEM  

NASA Astrophysics Data System (ADS)

Soil cohesion is an important variable to model soil detachment by runoff (Morgan et al., 1998a). As soil particles are not loose, soil detachment by runoff will be limited by the cohesion of the soil material. It is generally recognized that plant roots contribute to the overall cohesion of the soil. Determination of this increased cohesion and soil roughness however is complicated and measurements of shear strength and soil reinforcement by plant roots are very time- and labour consuming. A model approach offers an alternative for the assessment of soil cohesion provided by plant roots However, few erosion models account for the effects of the below-ground biomass in their calculation of erosion rates. Therefore, the main objectives of this study is to develop an approach to improve an existing soil erosion model (EUROSEM) accounting for the erosion-reducing effects of roots. The approach for incorporating the root effects into this model is based on a comparison of measured soil detachment rates for bare and for root-permeated topsoil samples with predicted erosion rates under the same flow conditions using the erosion equation of EUROSEM. Through backwards calculation, transport capacity efficiencies and corresponding soil cohesion values can be assessed for bare and root-permeated topsoils respectively. The results are promising and show that grass roots provide a larger increase in soil cohesion as compared with tap-rooted species and that the increase in soil cohesion is not significantly different under wet and dry soil conditions, either for fibrous root systems or for tap root systems. Relationships are established between measured root density values and the corresponding calculated soil cohesion values, reflecting the effects of roots on the resistance of the topsoil to concentrated flow incision. These relationships enable one to incorporate the root effect into the soil erosion model EUROSEM, through adapting the soil cohesion input value. A scenario analysis performed with EUROSEM for different vegetation treatments, indicates that runoff and soil loss on root-permeated topsoils are slightly higher as compared to fully covered grass fields or harvested grass fields with some plant residue left, but much smaller as compared to bare topsoils. Moreover, when re-vegetating bare soils, roots are responsible for a large part of the reduction in soil loss and runoff by concentrated flow. Hence, this analysis shows that the contribution of roots to soil cohesion is very important for preventing soil loss and reducing runoff volume. The increase in soil shear strength due to the binding effect of roots on soil particles is two orders of magnitude lower as compared with soil reinforcement achieved when roots mobilize their tensile strength during soil shearing and root breakage.

de Baets, S.; Poesen, J.; Torri, D.; Salvador, M. P.

2009-04-01

208

Role of vegetation in interplay of climate, soil and groundwater recharge in a global dataset  

NASA Astrophysics Data System (ADS)

Groundwater is an essential resource for people and ecosystems worldwide. Our capacity to ameliorate predicted global water shortages and to maintain sustainable water supplies depend on a better understanding of the controls of recharge and how vegetation change may affect recharge mechanisms. The goals of this study are to quantify the importance of vegetation as a dominant control on recharge globally and to compare the importance of vegetation with other hydrologically important variables, including climate and soil. We based our global analysis on > 500 recharge estimates from the literature that contained information on vegetation, soil and climate or location. Plant functional types significantly affected groundwater recharge rates substantially. After climatic factors (water inputs, PET, and seasonality), vegetation types explained about 15% of the residuals in the dataset. Across all climatic factors, croplands had the highest recharge rates, followed by grasslands, scrublands and woodlands (average recharge: 75, 63, 30, 22 mm/yr respectively). Recharge under woodlands showed the most nonlinear response to water inputs. Differences in recharge between the vegetation types were more exaggerated at arid climates and in clay soils, indicating greater biological control on soil water fluxes in these conditions. Our results shows that vegetation greatly affects recharge rates globally and alters relationship between recharge and physical variables allowing us to better predict recharge rates globally.

Kim, J. H.; Jackson, R. B.

2010-12-01

209

The fate of exogenous iodine in pot soil cultivated with vegetables.  

PubMed

A pot experiment was conducted to explore a more effective approach to enhancing vegetable uptake of soil iodine, with the ultimate goal of using agricultural fortification as a measure to prevent iodine deficiency disorders in local communities. Two types of iodine fertilizers were added separately to pot soil samples at various dosages. The fortified soil in each of the flower pots was seeded with one of four test crops (pakchoi, celery, pepper, and radish) in an effort to examine the effect of vegetable cultivation. The fate and residual levels of the exogenous iodine in the fortified soil samples were then monitored and quantified. The data showed that the soil iodine contents decreased with time (and hence with plant growth as well). At the second cutting, iodine from the inorganic form (KI) as the exogenous source was reduced to approximately 50% (41.6-61.0%) of the applied dose, whereas that in soil fortified with the seaweed fertilizer was down to approximately 60% (53.9-71.5%). The abilities of the edible portion of the four vegetables in accumulating the soil iodine were as follows: pakchoi > celery > radish > pepper. On the whole, iodine residues were found less in soil cultivated with vegetables. Vegetable cultivation appeared to have enhanced the soil content of the water-soluble form of iodine somewhat, especially in soil fortified with the inorganic forms. There also appeared to be a significant negative correlation between the residual iodine and its dissolution rate in soil. Overall, the results of the present study pointed toward the direction that the seaweed fertilizer tends to be a (more) preferred source of agricultural fortification in promoting human iodine nutrition. PMID:18386132

Hong, Chun-lai; Weng, Huan-xin; Yan, Ai-lan; Islam, Ejaz-ul

2008-04-02

210

RELATIONSHIP BETWEEN SOIL CHARACTERISTICS AND HALOPHYTIC VEGETATION IN COASTAL REGION OF NORTH CHINA  

Microsoft Academic Search

Plant-soil relationship of saline coastal plain of north China was studied. Principle component analysis (PCA) and cluster analysis were used to generate a hypothesis that the distribution pattern of halophytic vegetation was influenced by the variation in soil properties. The hypothesis was tested by canonical correlation analysis (CCA). PCA results showed that salinity, pH, moisture and available nitrogen were the

WEI-QIANG LI; LIU XIAO-JING; M. AJMAL KHAN; BILQUEES GUL

2008-01-01

211

The Vertical Distribution of Soil Organic Carbon and Its Relation to Climate and Vegetation  

Microsoft Academic Search

As the largest pool of terrestrial organic carbon, soils interact strongly with atmospheric composition, climate, and land cover change. Our capacity to predict and ameliorate the consequences of global change depends in part on a better understanding of the distributions and controls of soil organic carbon (SOC) and how vegetation change may affect SOC distributions with depth. The goals of

Esteban G. Jobbagy; Robert B. Jackson

2000-01-01

212

Method to estimate the concentration of elements in smoke from burning vegetation growing in contaminated soil.  

National Technical Information Service (NTIS)

The Savannah River Site has areas where soil is contaminated with metals and/or radionuclides. Many of these areas are surrounded by native vegetation which is growing adjacent to the area and where the roots have penetrated into the contaminated soil of ...

C. E. Murphy

1991-01-01

213

Changes in vegetation and soil properties along a slope on overgrazed and eroded rangelands  

Microsoft Academic Search

Rangelands, generally located on steep semi-arid zones, have a special importance in resource management. Continued overgrazing and erosion cause range degradation by altering plant communities and soil properties. The objective of this study was to determine changes in vegetation and soil properties along a slope on overgrazed and moderately eroded rangelands. Four study sites with three landscape positions: summit, backslope

Taskin Oztas; Ali Koc; Binali Comakli

2003-01-01

214

Effects of nitrogen deposition on soil and vegetation in primary succession stages in inland drift sands  

Microsoft Academic Search

Background and aims Primary succession was studied in acid inland drift sands. Main research questions were: 1) How do vegetation and soil change during succession? 2) How are soil parameters and species abundance affected by atmospheric nitrogen deposition? Methods One hundred sixty-five plots were selected in 21 drift sands throughout The Netherlands, divided over eight succession stages from bare sand

L. B. Sparrius; J. Sevink; A. M. Kooijman

2012-01-01

215

Invasion of a deciduous forest by earthworms: Changes in soil chemistry, microflora, microarthropods and vegetation  

Microsoft Academic Search

Ecosystems of northern North America existed without earthworm fauna until European settlers arrived and introduced European species. The current extent of invasion by some of these species, Lumbricus terrestris L., Octolasion tyrtaeum Savigny and Dendrobaena octaedra Savigny, into an aspen forest in the Canadian Rocky Mountains and the effects of the invasion on soil chemistry, microflora, soil microarthropods and vegetation

Nico Eisenhauer; Stephan Partsch; Dennis Parkinson; Stefan Scheu

2007-01-01

216

Contamination of soil and vegetation near a zinc smelter by zinc, cadmium, copper, and lead  

Microsoft Academic Search

Metal oxide fumes escaping from two zinc smelters in Palmerton, Pa., have highly contaminated soil and vegetation with zinc, cadmium, copper, and lead. Within 1 km of the smelters, 135,000 parts per million (ppm) zinc, 1750 ppm cadmium, 2000 ppm copper, and 2000 ppm lead have been measured in the Oâ horizon. Approximately 90% of metals deposited on the soil

Marilyn J. Buchauer

1973-01-01

217

The impact of Precipitation and Grassland Vegetation on Soil Moisture Dynamics  

NASA Astrophysics Data System (ADS)

The primary objective of this study was to assess the impact of grassland vegetation and precipitation (defined by the temporal pattern of water deposition and cumulative rainfall) on near-surface hydrology. Using a randomized block design experiment in a greenhouse, we monitored soil-moisture dynamics in mesocosms planted with three types of grassland vegetation found in California (mixed California grassland, avena grass monoculture, and erodium forb monoculture). We observed that above ground biomass production was strongly influenced by rainfall amount, with most productivity in the mid-level rainfall treatment. Soil moisture content (SMC) was best predicted by rainfall, stage of plant growth, and the interaction between these two parameters. Surprisingly, SMC did not depend on species composition of the grassland. The role of ET in drying the soil was influenced by the interaction between growth stage and rainfall, and to a lesser extend by the interaction between vegetation type and growth stage. When combined, seasonal precipitation and vegetation influenced the near-surface hydrology in ways that cannot be predicted from manipulation of a single variable. These results emphasize the importance of the interactive effects of precipitation and vegetation on soil moisture dynamics, and the potential for feedbacks since soil moisture affects vegetation. This study was supported by the Program for Ecosystem Research, Office of Science, U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

Salve, R.; Sudderth, E. A.; St. Clair, S. B.; Torn, M. S.

2009-12-01

218

Parsimonious modeling of vegetation dynamics for ecohydrologic studies of water-limited ecosystems  

NASA Astrophysics Data System (ADS)

The structure and function of vegetation regulate fluxes across the biosphere-atmosphere interface with large effects in water-limited ecosystems. Vegetation dynamics are often neglected in hydrological modeling except for simple prescriptions of seasonal phenology. However, changes in vegetation densities, influencing the partitioning of incoming solar energy into sensible and latent heat fluxes, can result in long-term changes in both local and global climates with resulting feedbacks on vegetation growth. This paper seeks a simple vegetation dynamics model (VDM) for simulation of the leaf area index (LAI) dynamics in hydrologic models. Five variants of a VDM are employed, with a range of model complexities. The VDMs are coupled to a land surface model (LSM), with the VDM providing the LAI evolution through time and the LSM using this to compute the land surface fluxes and update the soil water contents. We explore the models through case studies of water-limited grass fields in California (United States) and North Carolina (United States). Results show that a simple VDM, simulating only the living aboveground green biomass (i.e., with low parameterization), is able to accurately simulate the LAI. Results also highlight the importance of including the VDM in the LSM when studying the climate-soil-vegetation interactions over moderate to long timescales. The inclusion of the VDM in the LSM is demonstrated to be essential for assessing the impact of interannual rainfall variability on the water budget of a water limited region.

Montaldo, Nicola; Rondena, Roberta; Albertson, John D.; Mancini, Marco

2005-10-01

219

Modeling the effects of historical vegetation change on near-surface atmosphere in the northern Chihuahuan Desert  

Technology Transfer Automated Retrieval System (TEKTRAN)

Our goal was to evaluate the effects of a broad-scale change in vegetation from grasslands in the mid-1800s to shrublands in the late 1900’s on weather and climate. Vegetation and soil maps for 1858 and 1998 were used to run a fully coupled atmospheric-biospheric model for two times during the growi...

220

[Characteristics of soil nematode communities in coastal wetlands with different vegetation types].  

PubMed

An investigation was conducted on the characteristics of soil nematode communities in different vegetation belts (Spartina alterniflora belt, Sa; Suaeda glauca belt, Sg; bare land, B1; Phragmites australis belt, Pa; and wheat land, Wl) of Yancheng Wetland Reserve, Jiangsu Province of East China. A total of 39 genera and 20 families of soil nematodes were identified, and the individuals of dominant genera and common genera occupied more than 90% of the total. The total number of the nematodes differed remarkably with vegetation belts, ranged from 79 to 449 individuals per 100 grams of dry soil. Wheat land had the highest number of soil nematodes, while bare land had the lowest one. The nematode ecological indices responded differently to the vegetation belts. The Shannon index (H) and evenness index (J) decreased in the order of Pa > Sg > Wl > Sa > Bl, and the dominance index (lambda) was in the order of Bl > Sa > Wl > Sg > Pa, suggesting that the diversity and stability of the nematode community in bare land were lower than those in the other vegetation belts, and the nematode community in the bare land tended to be simplified. The maturity index (MI) was higher in uncultivated vegetation belts than in wheat land, suggesting that the wheat land was disturbed obviously. The nematode community structure differed significantly with vegetation belts, and the main contributing species in different vegetation belts also differed. There existed significant correlations between the soil physical and chemical characteristics and the nematode numbers, trophic groups, and ecological indices. Our results demonstrated that the changes of soil nematode community structure could be used as an indicator well reflecting the diversity of vegetation belt habitat, and an important bio-indicator of coastal wetland ecosystem. PMID:23431791

Liu, Bei-Bei; Ye, Cheng-Long; Yu, Li; Jiao, Jia-Guo; Liu, Man-Qiang; Hu, Feng; Li, Hui-Xin

2012-11-01

221

A physically based statistical methodology for surface soil moisture retrieval in the Tibet Plateau using microwave vegetation indices  

Microsoft Academic Search

A methodology for surface soil moisture measurement was developedMVIs are a function of vegetation water content or transmissivityThe methodology was shown to be effective for areas with sparse vegetation

T. J. Zhao; L. X. Zhang; J. C. Shi; L. M. Jiang

2011-01-01

222

Transfer of metals from soil to vegetables and possible health risk assessment.  

PubMed

Metal contamination in agricultural soils is of increasing concern due to food safety issues and potential health risks. Accumulation of Heavy and trace metals in vegetables occur by various sources but soil is considered the major one. Consumption of vegetables containing (heavy/trace) metals is one of the main ways in which these elements enter the human body. Once entered, heavy metals are deposited in bone and fat tissues, overlapping noble minerals and cause an array of diseases. The present study aimed to investigate the concentration of different metals in agricultural soil and vegetables grown on those soils and to evaluate the possible health risks to human body through food chain transfer. Contamination levels in soils and vegetables with metals were measured and transfer factors (TF) from soil to vegetables and its health risk were calculated accordingly. Results showed that concentration of Si, Ba, K, Ca, Mg Fe, Sc, V, Cr, Cu, Zn, As, Mn, Co, Ni, Se, Sr, Mo, and Cd in soil is higher than the World Average value and Al, Ti and Pb is lower than the World Average value whereas concentration of toxic elements like As, Co, Cu, Mn, Pb, Se, Ni, V and Zn in vegetable samples are below the World Average value. The intake of toxic metals (Fe, Cu, Mn, Zn Co, Cr, V, Ni, Pb and Cd) from vegetables is not high and within the permissible limit recommended by WHO, Food & Nutritional Board and US EPA. The Hazard Quotient (HQ) for Fe, Cu, Co, Cr, V, Ni, Pb, Mn, Zn and Cd were calculated which showed a decreasing order of Cd>Mn>Zn>Pb>Cu>Fe>Ni>V=Co>Cr. Highest HQ value found for Cd (2.543) which is above the safe value. PMID:24010043

Jolly, Yeasmin Nahar; Islam, Ashraful; Akbar, Shawkat

2013-08-15

223

A Broad Approach to Abrupt Boundaries: Looking Beyond the Boundary at Soil Attributes within and Across Tropical Vegetation Types  

PubMed Central

Most research on boundaries between vegetation types emphasizes the contrasts and similarities between conditions on either side of a boundary, but does not compare boundary to non-boundary vegetation. That is, most previous studies lack suitable controls, and may therefore overlook underlying aspects of landscape variability at a regional scale and underestimate the effects that the vegetation itself has on the soil. We compared 25 soil chemistry variables in rainforest, sclerophyll vegetation and across rainforest-sclerophyll boundaries in north-eastern Queensland, Australia. Like previous studies, we did find some contrasts in soil chemistry across vegetation boundaries. However we did not find greater variation in chemical parameters across boundary transects than in transects set in either rainforest or woodland. We also found that soil on both sides of the boundary is more similar to “rainforest soil” than to “woodland soil”. Transects in wet sclerophyll forests with increasing degrees of rainforest invasion showed that as rainforest invades wet sclerophyll forest, the soil beneath wet sclerophyll forest becomes increasingly similar to rainforest soil. Our results have implications for understanding regional vegetation dynamics. Considering soil-vegetation feedbacks and the differences between soil at boundaries and in non-boundary sites may hold clues to some of the processes that occur across and between vegetation types in a wide range of ecosystems. Finally, we suggest that including appropriate controls should become standard practice for studies of vegetation boundaries and edge effects worldwide.

Warman, Laura; Bradford, Matt G.; Moles, Angela T.

2013-01-01

224

A broad approach to abrupt boundaries: looking beyond the boundary at soil attributes within and across tropical vegetation types.  

PubMed

Most research on boundaries between vegetation types emphasizes the contrasts and similarities between conditions on either side of a boundary, but does not compare boundary to non-boundary vegetation. That is, most previous studies lack suitable controls, and may therefore overlook underlying aspects of landscape variability at a regional scale and underestimate the effects that the vegetation itself has on the soil. We compared 25 soil chemistry variables in rainforest, sclerophyll vegetation and across rainforest-sclerophyll boundaries in north-eastern Queensland, Australia. Like previous studies, we did find some contrasts in soil chemistry across vegetation boundaries. However we did not find greater variation in chemical parameters across boundary transects than in transects set in either rainforest or woodland. We also found that soil on both sides of the boundary is more similar to "rainforest soil" than to "woodland soil". Transects in wet sclerophyll forests with increasing degrees of rainforest invasion showed that as rainforest invades wet sclerophyll forest, the soil beneath wet sclerophyll forest becomes increasingly similar to rainforest soil. Our results have implications for understanding regional vegetation dynamics. Considering soil-vegetation feedbacks and the differences between soil at boundaries and in non-boundary sites may hold clues to some of the processes that occur across and between vegetation types in a wide range of ecosystems. Finally, we suggest that including appropriate controls should become standard practice for studies of vegetation boundaries and edge effects worldwide. PMID:23593312

Warman, Laura; Bradford, Matt G; Moles, Angela T

2013-04-10

225

Changes in Soil Properties and Vegetable Growth in Preparation for Organic Farming in Hawaii  

Microsoft Academic Search

Changes in soil properties and vegetable growth were quantified on a low-fertility tropical soil. Four treatments (two composts, urea, and control) were applied to an Oxisol (Rhodic Haplustox, Wahiawa series) in a field on Oahu, Hawaii. Chinese cabbage (Brassica rapa, Chinensis group) and eggplant (Solanum melongena) were grown sequentially as test crops. Soil quality as measured by hot-water-soluble carbon, dehydrogenase

Maria E. Ortiz-Escobar; N. V. Hue

2011-01-01

226

Soil and vegetation carbon pools in a mountainous watershed of Nepal  

Microsoft Academic Search

Assessment of carbon stocks in vegetation and soil is a basic step in evaluating the carbon sequestration potential of an\\u000a ecosystem. We collected soil (core and composite) samples from 0–10, 10–20, 20–40, and 40–70 cm depths, or down to the bed\\u000a rock, in the soil profile of four types of forest (managed dense Shorea (DS), degraded forest (DF), pine mixed (PS),

Bharat Man Shrestha; Bal Ram Singh

2008-01-01

227

Polycyclic aromatic hydrocarbons (PAHs) in agricultural soil and vegetables from Tianjin  

Microsoft Academic Search

Several types of vegetables were collected from two contaminated sites in Tianjin, China. The bulk soil and the rhizosphere soil samples were also collected from the same plots. Sixteen PAHs in the samples were measured. The total concentrations of PAH16 in the bulk soil from the two sites were 1.08 and 6.25 ?g\\/g, respectively, with similar pattern. The concentrations of

S. Tao; Y. H. Cui; F. L. Xu; B. G. Li; J. Cao; W. X. Liu; G. Schmitt; X. J. Wang; W. R. Shen; B. P. Qing; R. Sun

2004-01-01

228

The Interrelationship Between The Spatial Distribution Of Microorganisms And Vegetation In Forest Soils  

Microsoft Academic Search

Recent advances in techniques for investigating soil organisms and evaluating spatial structure have improved our understanding\\u000a of the spatial dynamics of the soil microbial community. Identifying the scale at which microbial community function and interact\\u000a in forest soils is essential to designing sampling schemes that will allow us to adequately evaluate the complex relationships\\u000a between the microbial community and vegetation.

Sherry J. Morris; William J. Dress

229

Heterogeneity as an index of anthropogenic disturbance of soil and vegetation in urban Parks  

NASA Astrophysics Data System (ADS)

The conditions of urban ecosystems depend on a wide range of anthropogenic factors, one of which is visitor pressure on urban parks. This study aims: (1) to analyze soil properties and vegetation characteristics of different open areas, and (2) to determine an index of disturbance for these areas, according to their spatial heterogeneity. The study was conducted in Tel-Aviv, and addressed two scales: (1) Land Use Units (municipal parks and vacant lots); and (2) Microenvironment (under tree, under bush, herbaceous area, lawn, and path). In each type of microenvironment, soil was sampled at seven points, from layers at two depths (0-2 and 5-10 cm). Before the sampling, penetration depth, litter biomass and vegetation characteristics (vegetation cover, number of species, and vegetation height) were determined in the field. In each soil sample gravimetric soil moisture and organic matter contents were determined, and pH, electrical conductivity and soluble-ion contents were measured in a 1:1 water extraction. The level of disturbance by visitors was scored for each microenvironment according to field evidence of trampling, such as lack of vegetation cover and litter biomass. The results show strong differences in soil properties among the various microenvironments: penetration depth ranged from a few millimeters up to ~ 3 cm; organic matter content from less than 1% to 10%; soil moisture content from a few percents to ~ 30%; electrical conductivity from ~ 0.3 to ~2 dS/m; sodium content from ~ 1 to 7.5 meq/kg; chlorine content from ~ 0.5 to ~9 meq/kg; and litter biomass from 0.5 to 1.4 kg/m2. The vegetation characteristics also varied among the microenvironments: vegetation cover ranged from 11 to 99 %; number of species from 2 to11; and vegetation height from 5 to 35 cm. In order to assess the level of heterogeneity of soil and vegetation, an integral index, based on the number of Duncan groups, has been calculated. Regarding the Scale of Land Use unit, it was found that the highest heterogeneity of soil characteristics corresponded with the lowest species richness. For the smaller-scale unit - Microenvironment - an index was developed that defines the status of disturbance, and it was used to sort the microenvironments into several groups. High correlation between percentiles and averages of soil properties was found for the microenvironments. This hints at a fractal structure of soil properties distribution at the microenvironment level.

Zhevelev, H.; Sarah, P.

2012-04-01

230

Experimental Test of a Mechanistic Model of Production, Flux and Gas Bubble Zonation in Non-vegetated Flooded Rice Field Soil  

Microsoft Academic Search

Anoxic wetlands are an important source for the greenhouse gas CH4, much of which is emitted in form of gas bubbles. The conditions for formation of gas bubbles have recently been described\\u000a by an analytical model, which allows the prediction of fluxes by first physical principles using the knowledge of gas concentration\\u000a profiles and\\/or gas production rates. We tested parts

Andre Kusmin; Nikolai M. Bazhin; Ralf Conrad

2006-01-01

231

Modelling Soil respiration in agro-ecosystems  

NASA Astrophysics Data System (ADS)

A soil respiration model was developed to simulate soil respiration in crops on a daily time step. The soil heterotrophic respiration component was derived from Century (Parton et al., 1987). Soil organic carbon is divided into three major components including active, slow and passive soil carbon. Each pool has its own decomposition rate coefficient. Carbon flows between these pools are controlled by carbon inputs (crop residues), decomposition rate and microbial respiration loss parameters, both of which are a function of soil texture, soil temperature and soil water content. The model assumes that all C decompositions flows are associated with microbial activity and that microbial respiration occurs for each of these flows. Heterotrophic soil respiration is the sum of all these microbial respiration processes. To model the soil autotrophic respiration component, maintenance respiration is calculated from the nitrogen content and assuming an exponential relationship to account for temperature dependence (Ryan et al., 1991). Growth respiration is calculated assuming a dependence on both growth rate and construction cost of the considered organ (MacCree et al., 1982) A database, made of four different soil and climate conditions in mid-latitude was used to study the two components of the soil respiration model in wheat fields. Soil respiration were measured in three winter wheat fields at Lamasquère (43°49'N, 01°23'E, 2007) and Auradé (43°54'N, 01°10'E, 2008), South-West France and Lonzée (50°33'N, 4°44'E, 2007), Belgium, and in a spring wheat field at Ottawa (45°22'N, 75°43'W, 2007, 2011), Ontario, Canada. Manual closed chambers were used in the French sites. The Belgium and Canadian sites were equipped with automated closed chamber systems, which continuously collected 30-min soil respiration exchanges. All the sites were also equipped with eddy flux towers. When eddy flux data were collected over bare soil, the net ecosystem exchange (NEE) was equal to soil respiration exchange. These NEE data were used to validate the model. The carbon pools in the model needed to be initialized at each site, by running iteratively simulations of a same climatic year in a given wheat field, until equilibrium was reached. The model performance was evaluated by comparing simulated and measured soil respiration values. The predicted heterotrophic soil respiration compared well with the seasonal dynamic fluxes at each site. The measured values of heterotrophic soil respiration were also well calculated by the model. Then, the autotrophic soil respiration was validated. The parameterization of the Root/Shoot ratio dynamic was a key factor to retrieve the seasonal dynamic of observed root+rhizosphere respiration during vegetation growth period. Finally, the total soil respiration model was validated on independent datasets from calibration, of four wheat crops and could be used as a prediction model for comparison between different scenario of irrigation, ploughing, or crop rotation.

Delogu, Emilie; LeDantec, Valerie; Mordelet, Patrick; Buysse, Pauline; Aubinet, Marc; Pattey, Elizabeth

2013-04-01

232

Indicators of nitrate in wetland surface and soil-waters: interactions of vegetation and environmental factors  

NASA Astrophysics Data System (ADS)

This paper describes a new bio-indicator method for assessing wetland ecosystem health; as such, the study is particularly relevant to current legislation such as the EU Water Framework Directive, which provides a baseline of the current status of surface waters. Seven wetland sites were monitored across northern Britain, with model construction data for predicting eco-hydrological relationships collected from five sites during 1999. Two new sites and one repeat site were monitored during 2000 to provide model test data. The main growing season for the vegetation, and hence the sampling period, was May-August during both years. Seasonal mean concentrations of nitrate (NO3-) in surface and soil water samples during 1999 ranged from 0.01 to 14.07 mg N l-1, with a mean value of 1.01 mg N l-1. During 2000, concentrations ranged from trace level (<0.01 mg N l-1) to 9.43 mg N l-1, with a mean of 2.73 mg N l--1. Surface and soil-water nitrate concentrations did not influence plant species composition significantly across representative tall herb fen and mire communities. Predictive relationships were found between nitrate concentrations and structural characteristics of the wetland vegetation, and a model was developed which predicted nitrate concentrations from measures of plant diversity, canopy structure and density of reproductive structures. Two further models, which predicted stem density and density of reproductive structures respectively, utilised nitrate concentration as one of the independent predictor variables. The models were tested where appropriate using data collected during 2000. This approach is complementary to species-based monitoring, representing a useful and simple tool to assess ecological status in target wetland systems and has potential for bio-indication purposes.

Kennedy, M. P.; Murphy, K. J.

233

A model of arctic tundra vegetation derived from topographic gradients  

Microsoft Academic Search

We present a topographically-derived vegetation model (TVM) that predicts the landscape patterns of arctic vegetation types in the foothills of the Brooks Range in northern Alaska. In the Arctic there is a strong relationship between water and plant structure and function and TVM is based on the relationships between vegetation types and slope (tan ß) and discharge (d), two independent

Bertram Ostendorf; James F. Reynolds

1998-01-01

234

Vegetation patterns influence on soil microbial biomass and functional diversity in a hilly area of the Loess Plateau, China  

Microsoft Academic Search

Purpose  Shifts of microbial biomass and functional diversity under different vegetation patterns can impact the soil processes, and\\u000a the specific knowledge about this can be used to develop sound vegetation restoration strategies. This study was devoted to\\u000a examine the effects of different vegetation patterns on microbial biomass and functional diversity and explore the relationship\\u000a between soil erosion and soil microbial properties

Chanjuan Hu; Bojie Fu; Guohua Liu; Tiantian Jin; Lei Guo

2010-01-01

235

soil to compaction, organic matter removal, and vegetation control1  

Microsoft Academic Search

We tested three disturbance hypotheses in young conifer plantations: H,: soil compaction and removal of surface organic matter produces sustained changes in microbial community size, activity, and structure in mineral soil; H2: microbial community characteristics in mineral soil are linked to the recovery of plant diversity; and H3: community responses are strongly modified by regional climate. Microbial biomass, respiration, carbon

Matt D. Busse; Samual E. Beattie; Robert F. Powers; Felipe G. Sanchez; Allan E. Tiarks

236

Soil moisture profile variability in land-vegetation- atmosphere continuum  

Microsoft Academic Search

Soil moisture is of critical importance to the physical processes governing energy and water exchanges at the land-air boundary. With respect to the exchange of water mass, soil moisture controls the response of the land surface to atmospheric forcing and determines the partitioning of precipitation into infiltration and runoff. Meanwhile, the soil acts as a reservoir for the storage of

Wanru Wu

2000-01-01

237

INNOVATIVE APPROACHES FOR SOIL FUMIGATION IN VEGETABLE PRODUCTION SYSTEMS  

Technology Transfer Automated Retrieval System (TEKTRAN)

An apparatus was developed for injecting soil fumigants beneath raised planting beds covered by plastic mulch without disturbing the integrity of the beds. Soil fumigation using a mixture of 1,3-dichloropropene (1,3-D) and chloropicrin (Pic) was combined with abbreviated soil solarization periods, v...

238

[Study on nutrient and salinity in soil covered with different vegetations in Shuangtaizi estuarine wetlands].  

PubMed

Nutrient elements and salinity in soil covered by different vegetations including Phragmites australis (Clay.) Trin., Typha orientalis Presl., Puccinellia distans Parl, and Suaeda salsa in Shuangtaizi estuarine wetlands were investigated to study their distribution characteristics and to reveal the nutrient element variation during the vegetation succession processes. Results indicated that total potassium, total phosphorus and salinity were different significantly in soil between different plant communities while available phosphorus, total nitrogen, available nitrogen, available potassium, total sulfur, iron and soil organic carbon were different insignificantly. Correlation analysis suggested that soil organic carbon were related significantly to total nitrogen, available phosphorus, available potassium, which implied that decomposition of plant litter might be the mail source of soil nitrogen and available nutrient. Salinity was significantly related to total phosphorus and iron in soil. In Shuangtaizi estuarine wetland soil, ratios of carbon to nitrogen (R(C/N)) was in the range of 12.21-26.33 and the average value was 18.21, which was higher than 12.0. It indicated that soil organic carbon in Shuangtaizi estuarine mainly came from land but not ocean and plants contributed the most of soil organic matters. There was no significant difference in R(C/N) between soil from the four plant communities (F = 1.890, p = 0.151). R(C/N) was related significantly to sol salinity (r = 0.346 3, p = 0.035 8) and was increasing with soil salinity. PMID:22165232

Song, Xiao-Lin; Lü, Xian-Guo; Zhang, Zhong-Sheng; Chen, Zhi-Ke; Liu, Zheng-Mao

2011-09-01

239

Development of vegetation based soil quality indices for mineralized ...  

Treesearch

... impacted by different types of geologic mineralization using the relationship between ... cover and shrub density were measured for the vegetative communities. ... three to six abiotic parameters, the latter consisting of nutrients and metals.

240

Large herbivores may alter vegetation structure of semi-arid savannas through soil nutrient mediation.  

PubMed

In savannas, the tree-grass balance is governed by water, nutrients, fire and herbivory, and their interactions. We studied the hypothesis that herbivores indirectly affect vegetation structure by changing the availability of soil nutrients, which, in turn, alters the competition between trees and grasses. Nine abandoned livestock holding-pen areas (kraals), enriched by dung and urine, were contrasted with nearby control sites in a semi-arid savanna. About 40 years after abandonment, kraal sites still showed high soil concentrations of inorganic N, extractable P, K, Ca and Mg compared to controls. Kraals also had a high plant production potential and offered high quality forage. The intense grazing and high herbivore dung and urine deposition rates in kraals fit the accelerated nutrient cycling model described for fertile systems elsewhere. Data of a concurrent experiment also showed that bush-cleared patches resulted in an increase in impala dung deposition, probably because impala preferred open sites to avoid predation. Kraal sites had very low tree densities compared to control sites, thus the high impala dung deposition rates here may be in part driven by the open structure of kraal sites, which may explain the persistence of nutrients in kraals. Experiments indicated that tree seedlings were increasingly constrained when competing with grasses under fertile conditions, which might explain the low tree recruitment observed in kraals. In conclusion, large herbivores may indirectly keep existing nutrient hotspots such as abandoned kraals structurally open by maintaining a high local soil fertility, which, in turn, constrains woody recruitment in a negative feedback loop. The maintenance of nutrient hotspots such as abandoned kraals by herbivores contributes to the structural heterogeneity of nutrient-poor savanna vegetation. PMID:21225433

van der Waal, Cornelis; Kool, Ada; Meijer, Seline S; Kohi, Edward; Heitkönig, Ignas M A; de Boer, Willem F; van Langevelde, Frank; Grant, Rina C; Peel, Mike J S; Slotow, Rob; de Knegt, Henrik J; Prins, Herbert H T; de Kroon, Hans

2011-01-12

241

Influence of vegetation spatial heterogeneity on soil enzyme activity in burned Mediterranean areas  

NASA Astrophysics Data System (ADS)

Mediterranean ecosystems are commonly considered resilient to wildfires. However, depending on fire severity and recurrence, post-fire climatic conditions and plant community type, the recovery rate of the vegetation can greatly vary. Often, the post-fire vegetation cover remains low and sparsely distributed many years after the wildfire, which could have profound impacts on ecosystem functioning. In this work, we studied the influence of vegetation patchiness on soil enzyme activity (acid phosphatase, ?-glucosidase and urease), at the patch and landscape scales, in degraded dry Mediterranean shrublands affected by wildfires. At the patch scale, we assessed the variation in soil enzyme between bare soils and vegetation patches. At the landscape scale, we studied the relationships between soil enzyme activity and various landscape metrics (total patch cover, average interpatch length, average patch width, and patch density). The study was conducted in 19 sites in the Valencia Region (eastern Spain), which had been affected by large wildfires in 1991. Site selection aimed at capturing a wide range of the variability of post-fire plant recovery rates in Mediterranean areas. The activities of the three enzymes were significantly higher in soils under the vegetation canopies than in adjacent bare areas, which we attributed to the effect of plants on the soil amount of both enzyme substrates and enzymes. The differences between bare and plant microsites were larger in the case of the acid phosphatase and less marked for urease. The activity of acid phosphatase was also higher under patches of resprouter species than under patches of seeder species, probably due to the faster post-fire recovery and older age of resprouter patches in fire-prone ecosystems. Soil enzyme activities of ?-glucosidase and urease in both bare soils and vegetation patches showed no relationships with any of the landscape metrics analysed. However, the activity of acid phosphatase increased linearly with the total cover of vegetation patches, which is consistent with the strong effect of plant patches on the activity of this enzyme. According to our results, variations in the cover and composition of vegetation patches may have profound impacts on the soil enzyme activity and associated nutrient cycling processes in burned Mediterranean areas, particularly in the case of phosphorus. Keywords: wildfires, landscape metrics, Mediterranean shrublands, soil enzyme activity, resprouter species.

Mayor, Á. G.; Goirán, S.; Bautista, S.

2009-04-01

242

COMPARING THE CORRELATIVE HOLDRIDGE MODEL TO MECHANISTIC BIOGEOGRAPHICAL MODELS FOR ASSESSING VEGETATION DISTRIBUTION RESPONSE TO CLIMATIC CHANGE  

Microsoft Academic Search

A well-established and widely used correlative climate-vegetation model (Holdridge Life Zone model) was compared to three mechanistic simulation models (BIOME2, Dynamic Global Phytogeography Model (DOLY), and Mapped Atmosphere-Plant-Soil System (MAPSS)) for the conterminous United States under contemporary climate and a set of future climates prescribed by three Global Circulation Model experiments. Output from the mechanistic models were from the Ve-

DAVID N. YATES; TIMOTHY G. F. KITTEL; REGINA FIGGE CANNON

2000-01-01

243

Soil and water components of banded vegetation patterns  

Microsoft Academic Search

Banded landscapes are comprised of alternating bands of vegetation and bare ground aligned along the contours in arid and semi-arid regions (50–750 mm rainfall), on very gentle and uniform slopes (0.2–2%). Vegetated bands can be perpendicular to the direction of the dominant wind, or more frequently of the slope. Under given climatic conditions, slope gradient is the controlling factor of

C Valentin; J. M d'Herbès; J Poesen

1999-01-01

244

Estimation of energy and moisture fluxes for dynamic vegetation using coupled SVAT and crop-growth models  

NASA Astrophysics Data System (ADS)

A Soil Vegetation Atmosphere Transfer (SVAT) model, viz. Land Surface Process (LSP) model, is coupled with a widely used crop-growth model, DSSAT, to estimate energy and moisture fluxes at the land surface and in the vadose zone for growing vegetation. In this study, we present detailed observations of soil and crop characteristics, and various components of energy and water balance during a season-long field experiment for sweet corn. The data set is used to calibrate the LSP with Latin Hypercube Sampling and Pareto ranking. We compare the observations with model estimates of crop growth and development, land surface fluxes, soil moisture and temperature profiles from both the stand-alone LSP and coupled LSP-DSSAT models. We find that the model estimates of radiation fluxes, soil moisture, and soil temperature, by both the LSP and LSP-DSSAT are very similar, indicating that the LSP-DSSAT model can be used to simulate fluxes for dynamic vegetation without the need of in situ vegetation observations. Moreover, because coupling was achieved without structurally changing either of the models, the methodology in this study can be extended to coupling other SVAT and vegetation growth models.

Casanova, Joaquin J.; Judge, Jasmeet

2008-07-01

245

Vegetation effects on soil water erosion rates and nutrient losses at Santa Catarina highlands, south Brazil  

NASA Astrophysics Data System (ADS)

Water erosion involves three main processes: detachment, transport and deposition of soil particles. The main factors affecting water erosion are rainfall, soil, topography, soil management and land cover and use. Soil erosion potential is increased if the soil has no or very little vegetative cover of plants and/or crop residues, whereas plant and residue cover substantially decrease rates of soil erosion. Plant and residue cover protects the soil from raindrop impact and splash, tends to slow down the movement of surface runoff and allows excess surface water to infiltrate. Moreover, plant and residue cover improve soil physical, chemical and biological properties. Soils with improved structure have a greater resistance to erosion. By contrast, accelerated soil erosion is accentuated by deforestation, biomass burning, plowing and disking, cultivation of open-row crops, etc. The erosion-reducing effectiveness of plant and/or residue covers depends on the type, extent and quantity of cover. Vegetation and residue combinations that completely cover the soil are the most efficient in controlling soil. Partially incorporated residues and residual roots are also important, as these provide channels that allow surface water to move into the soil. The effectiveness of any crop, management system or protective cover also depends on how much protection is available at various periods during the year, relative to the amount of erosive rainfall that falls during these periods. Most of the erosion on annual row crop land can be reduced by leaving a residue cover greater after harvest and over the winter months, or by inter-seeding a forage crop. Soil erosion potential is also affected by tillage operations and tillage system. Conservation tillage reduces water erosion in relation to conventional tillage by increasing soil cover and soil surface roughness. Here, we review the effect of vegetation on soil erosion in the Santa Catarina highlands, south of Brazil, under subtropical climatic conditions. The area cropped under no tillage in Brazil has increased rapidly since 1990, especially in the southern region. This practice was first introduced in the 1970s as a strategy to control soil erosion and continuous declines in land productivity under conventional tillage systems. No tillage almost entirely keeps the previous crop residue on the surface. In the last 15 years soil and water losses by water erosion have been quantified for different soil tillage systems, diverse crop rotations and successive crop stages under simulated and natural rain conditions. Plot experiments showed that soil losses under no tillage systems with a vegetative cover were 98% lower when compared with conventionally tilled bare soil. Moreover water losses were 60% lower for these conditions. Conventional tillage (plowing + harrowing) in the presence of vegetative cover reduced soil losses and water losses by 80% and 50%, respectively, taken the uncultivated bare soil as a reference. The review includes the effect of vegetative cover on nutrient losses at the studied sites in the Santa Catarina highlands.

Bertol, I.; Barbosa, F. T.; Vidal Vázquez, E.; Paz Ferreiro, J.

2009-04-01

246

Transferfaktoren Boden-Pflanze fuer I-129 und Weidebewuchs. (Soil-plant-transfer factors for I-129 and pasture vegetation).  

National Technical Information Service (NTIS)

The transfer factors for soil/plant, I-129 and I-127 and pasture vegetation have been measured with soils developed by wethering of granite, jura and cretaceous formations. Greenhouse (Karlsruhe) and field experiments (Munich) have been performed using ly...

A. Haisch H. Schuettelkopf

1993-01-01

247

Responses of mountain forested watersheds to climate warming: interactions among snowmelt, soil/geology and vegetation water use (Invited)  

NASA Astrophysics Data System (ADS)

At regional scales, spatial variation in eco-hydrologic processes is a complex function of geology, soil, topography, climate and vegetation patterns. Understanding how these different controls vary and interact remains a key challenge for climate change impact assessment. In snow-dominated mountain environments, there is growing evidence that reduced snow accumulation and earlier melt is already occurring and is an important driver of summer streamflow and ecosystem responses. Modelling these responses requires estimation not only of the spatial pattern of melt response to warming, but also the convolution of these spatial patterns with vegetation water use and subsurface drainage. We use a coupled process-based model of ecosystem hydrologic and carbon cycling, RHESSys, to demonstrate that soil moisture drainage and storage characteristics exert a significant control on how forest water use, and streamflow respond to earlier snowmelt. We focus our modeling scenarios on sites with measurements of streamflow, and vegetation growth that can be used to evaluate model performance. We then use the model to show how the combined changes in snowmelt and terrestrial ecosystem responses alter streamflow regimes and may have important implications for aquatic and human communities. These modeling studies provide an expanded perspective on landscape-level sensitivities to climate warming, and can provide guidance for the strategic design of data assimilation and monitoring strategies.

Tague, C.; Choate, J.; Dugger, A. L.; Garcia, E.; Groulx, D.; Son, K.

2010-12-01

248

Modeling soil freezing dynamics  

Technology Transfer Automated Retrieval System (TEKTRAN)

Seasonally frozen soil strongly influences runoff and erosion on large areas of land around the world. In many areas, rain or snowmelt on seasonally frozen soil is the single leading cause of severe runoff and erosion events. As soils freeze, ice blocks the soil pores, greatly diminishing the permea...

249

The global carbon dioxide flux in soil respiration and its relationship to vegetation and climate  

NASA Astrophysics Data System (ADS)

Measured rates of soil respiration from terrestrial and wetland ecosystems are reviewed to define the annual global CO2 flux from soils, identify uncertainties in the global flux estimates, and to investigate the influences of temperature, precipitation, and vegetation on soil respiration rates. The annual global CO2 flux from soils is estimated to average 68 +/- 4 PgC/yr, based on extrapolations from biome land areas. On a global scale, soil-respiration rates are positively correlated with mean annual air temperatures and mean annual precipitation. There is a chosen correlation between mean annual net primary productivity of different vegetation biomes and their mean annual soil respiration rates. Estimates of soil C turnover rates range from 500 years in tundra and peaty wetlands to 10 years in tropical savannas. The impacts of human activities on soil-respiration rates are poorly documented, and vary among sites. Of particular importance are potential changes in temperatures and precipitation. Based on a review of in situ measurements, the Q10 value for total soil respiration has a median value of 2.4. Increased soil respiration with global warming is likely to provide a positive feedback to the greenhouse effect.

Raich, J. W.; Schlesinger, W. H.

1992-04-01

250

Changes of Soil Microbiological Properties Caused by Land Use Changing From Rice–Wheat Rotation to Vegetable Cultivation  

Microsoft Academic Search

A survey was done recently in Jiaxing city of Zhejiang Province in the Yangtze River Delta to compare the differences of soil microbiological properties among paddy soils with different land use including continuous open-field vegetable cultivation (OFVC), plastic-greenhouse vegetable cultivation (PGVC) and traditional rice–wheat rotation (RWR). The soil types included are percolating, permeable and waterlogged paddy soils. The results indicate

X. G. Lin; R. Yin; H. Y. Zhang; J. F. Huang; R. R. Chen; Z. H. Cao

2004-01-01

251

The establishment of heathland vegetation on ex-arable land: the response of Calluna vulgaris to soil acidification  

Microsoft Academic Search

The UK Biodiversity Action Plan has identified the creation of lowland heathland as an important objective. Heathland restoration studies have identified soil pH, elevated soil nutrients and large weed seed banks as major problems in the restoration of heathland vegetation on ex-arable land. Heathland vegetation is usually found on nutrient-poor acidic soils. Creating acidic soil conditions on ex-arable sites thus

Clare S. Lawson; Martin A. Ford; Jonathan Mitchley; John M. Warren

2004-01-01

252

Soil moisture characteristics and implications for vegetation regeneration in Sudan during the period 1965-2005.  

NASA Astrophysics Data System (ADS)

This study aims at better understanding the soil moisture (SM) characteristics as fundamental factors for vegetation regeneration in Sudan during the period 1965-2005. The Mann Kendall (MK) analysis was used to test the trend in the average monthly soil moisture (SM), rainfall and temperature data. Geographically weighted regression (GWR) was selected to study the SM, rainfall and temperature relations because it accounts for the local spatial variability and non-stationarity of these variables. To further understand dry and wet variations in terms of regeneration demand, the aridity index (AI) was used. The results of (MK) test showed that there were decreasing trends of SM on an annual and seasonal level and that the trend was less dramatic or softer in the dry season (November-April) than the wet season (May- October). That soil moisture variability followed closely that of rainfall and temperature, although there was a hint that SM variability followed temperature changes more closely than rainfall. The (GWR) model gave optimal results in semi-arid central Sudan. In the north due to lack of rainfall and in the south due to plant heterogeneity, the model did not perform so well. The spatio-temporal variability of the (AI) showed that the long-term average of (AI) was affected by the reported decline in rainfall during 1965-1985. The decadal (AI) average of 1995-2005 gave evidence of increases in rainfall that are reported since the mid-nineties. (AI) performed well in reflecting the wet conditions in Sudan. Very rare are the studies of soil moisture in Sudan, especially in the through way that is presented here.

El Haj El Tahir, M.; Xu, C.; Zengxin, Z.

2012-04-01

253

A Mathematical Model for Air Flow in a Vegetative Canopy  

Microsoft Academic Search

The objectives of this study are to investigate the turbulent transfer of momentum within a vegetative canopy and also to develop a mathematical model which expresses the aerodynamic roughness effects of the surface boundary in terms of the height, density, and drag characteristics of a vegetative canopy. To date three mathematical models have been formulated. The present model reflects both

Ronald M. Cionco

1965-01-01

254

Optimum vegetation characteristics, assimilation, and transpiration during a dry season: 1. Model description  

NASA Astrophysics Data System (ADS)

This paper presents a model to predict optimum vegetation characteristics in water stressed conditions. Starting point is the principle of homeostasis of water flow through the soil-vegetation-atmosphere continuum. Combining this with a biochemical model for photosynthesis, a relationship between photosynthetic capacity, stomatal regulation, and hydraulic properties of the vegetation is derived. Optimum photosynthetic capacity and internal carbon dioxide concentration are calculated using the assumption that growth is maximized. This optimality hypothesis is applied for three scenarios which are increasingly realistic. Optimum parameters reflect a strategy to deal with two tradeoffs: the trade-off between fast growth and avoidance of drought and between a high photosynthetic capacity and avoidance of high respiration losses. The theory predicts general boundary conditions for growth but does not consider effects of competition between species, fires, pest, and diseases or other limitations that occur locally. In a companion paper the theory is evaluated using a data set collected in sub-Mediterranean vegetation.

van der Tol, C.; Meesters, A. G. C. A.; Dolman, A. J.; Waterloo, M. J.

2008-03-01

255

Effects of vegetation on radon transport processes in soil  

Microsoft Academic Search

A large component of radon entry cannot be explained by pressure differences between the soil and inside the structures. The persistence of this radon entry even when the house is pressurized by 1 Pa indicates that it must be due to molecular diffusion. The radon entry rate as measured by accumulators below ground level (soil + concrete) is roughly 2

Borak

1991-01-01

256

[Pollution characteristics and accumulation of antibiotics in typical protected vegetable soils].  

PubMed

The occurrence and distribution of 14 selected antibiotics in soils from 20 protected vegetable fields in Shandong province were investigated by ultrasonic extraction and UPLC-MS/MS. The results showed that antibiotics were detected in all the soil samples, the dominant antibiotics were tetracycline, oxytetracycline, chlortetracycline and doxycycline with 100% detection rate, the concentration of which in soil ranged from 2.11-139.16, 6.06-332.02, 1.82-391.31, 2.20-248.56 microg x kg(-1), respectively. The total concentration of four compounds sigma (TCs) ranged from 26.79-1010.11 microg x kg(-1), with an average of 274 microg x kg(-1). All the sulfonamides (SAs), quinolones (QNs) and macrolides antibiotics (MACs) were also detected, except for chloramphenicoles. The total concentration of QNs [sigma (QNs)] in soils ranged from 0-1017.06 microg x kg(-1) and the average concentration was 73.05 microg x kg(-1) with detection rate of 85%, and the individual concentrations of SAs and MACs were quite low in soils. The results also showed that the distibution and concentration of antibiotics in soils grown different vegetables were quite different. Notably, the individual concentrations of QNs (NFC, OFC) were 373.73 microg x kg(-1) and 643.34 microg x kg(-1), respectively, which far exceeded the trigger value of the ecological risk (100 microg x kg(-1)). Thus, more attention should be paid to antibiotics pollution in protected vegetable soils. PMID:23213909

Yin, Chun-yan; Luo, Yong-ming; Teng, Ying; Zhang, Hai-bo; Chen, Yong-shan; Zhao, Yong-gang

2012-08-01

257

Vegetation and climate controls on potential CO2, DOC and DON production in northern latitude soils  

USGS Publications Warehouse

Climatic change may influence decomposition dynamics in arctic and boreal ecosystems, affecting both atmospheric CO2 levels, and the flux of dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) to aquatic systems. In this study, we investigated landscape-scale controls on potential production of these compounds using a one-year laboratory incubation at two temperatures (10?? and 30??C). We measured the release of CO2, DOC and DON from tundra soils collected from a variety of vegetation types and climatic regimes: tussock tundra at four sites along a latitudinal gradient from the interior to the north slope of Alaska, and soils from additional vegetation types at two of those sites (upland spruce at Fairbanks, and wet sedge and shrub tundra at Toolik Lake in northern Alaska). Vegetation type strongly influenced carbon fluxes. The highest CO2 and DOC release at the high incubation temperature occurred in the soils of shrub tundra communities. Tussock tundra soils exhibited the next highest DOC fluxes followed by spruce and wet sedge tundra soils, respectively. Of the fluxes, CO2 showed the greatest sensitivity to incubation temperatures and vegetation type, followed by DOC. DON fluxes were less variable. Total CO2 and total DOC release were positively correlated, with DOC fluxes approximately 10% of total CO2 fluxes. The ratio of CO2 production to DOC release varied significantly across vegetation types with Tussock soils producing an average of four times as much CO2 per unit DOC released compared to Spruce soils from the Fairbanks site. Sites in this study released 80-370 mg CO2-C g soil C-1 and 5-46 mg DOC g soil C-1 at high temperatures. The magnitude of these fluxes indicates that arctic carbon pools contain a large proportion of labile carbon that could be easily decomposed given optimal conditions. The size of this labile pool ranged between 9 and 41% of soil carbon on a g soil C basis, with most variation related to vegetation type rather than climate.

Neff, J. C.; Hooper, D. U.

2002-01-01

258

Influence of Vegetations' Metabolites on the Composition and Functioning of Soil Microbial Complex  

NASA Astrophysics Data System (ADS)

Microbiota is one of the major factors of soils fertility. It transforms organic substances in soil and, therefore, serves as the main component in the cycles of carbon and nitrogen. Microbial communities (MC) are characterized as highly diverse and extremely complex structures. This allows them to adapt to any affection and provide all the necessary biospheric functions. Hence, the study of their functional diversity and adaptivity of microbiota provides the key to the understanding of the ecosystems' functioning and their adaptivity to the human impact. The formation of MC at the initial stage is regulated by the fluxes of substrates and biologically active substances (BAS), which vary greatly in soils under different vegetations. These fluxes are presented by: low molecular weights organic substances (LMWOS), which can be directly included in metabolism of microbes; polymers, that can be decomposed to LMWOS by exoenzymes; and more complex compounds, having different "drug effects" (e.g. different types of phenolic acids) and regulating growth and enzymatic properties of microbiota. Therefore, the main hypothesis of the research was formulated as follows: penetration of different types of substrates and BAS into soil leads to the emergence of MC varying in enzymatic properties and structure. As a soil matrix we used the soil from the untreated variant of the lysimeter model experiment taking place in the faculty of Soil Science of the MSU for over the last 40 years. It was sieved with a 2mm sieves, humidified and incubated at 25C during one week. Subsequently, the samples were air-dried with occasional stirring for one more week. Thereafter, aliquots of the prepared soil were taken for the different experimental variants. The samples were rewetted with solutions of various substrates (glucose, cellulose, starch, etc.) and thoroughly mixed. The control variant was established with addition of deionised water. The samples were incubated at the 25C. During the incubation the rate of mineralisation of organic substances was assessed with CO2 measurements. In 5, 10 and 21 days of incubation the enzymatic properties of the formed MC were studied by the hydrolysis of fluorogenic substrates. The influence of BAS on enzymatic properties of MC were researched by addition of different concentrations of phenolic acids (e.g. salicylic, vanillic, benzoic, etc.) to the samples from various substrates treatments. The acute toxicity of BAS was studied with bacterial luminescent test. After the last measurement, the isolations of microorganisms on elective nutrient medias were made. The dominant microorganisms were collected to the library for further identification and physiological tests. MeOH-chloroform extraction of phospholipids were performed with the remaining samples. Finally, they were stored for subsequent FAME identifications. The obtained data prove that penetration of various substrates into the soil determines the formation of MC different in structure and properties. It was found, that EC50 of the most studied phenolic acids are similar to naturally occurring concentrations. This means that they can be the real drivers of forming endemical MC under various vegetations along with the plant-specific fluxes of nutrients.

Biryukov, Mikhail

2013-04-01

259

The impact of using area-averaged land surface properties —topography, vegetation condition, soil wetness—in calculations of intermediate scale (approximately 10 km 2) surface-atmosphere heat and moisture fluxes  

Microsoft Academic Search

It is commonly assumed that biophysically based soil-vegetation-atmosphere transfer (SVAT) models are scale-invariant with respect to the initial boundary conditions of topography, vegetation condition and soil moisture. In practice, SVAT models that have been developed and tested at the local scale (a few meters or a few tens of meters) are applied almost unmodified within general circulation models (GCMs) of

Piers J. Sellers; Mark D. Heiser; Forrest G. Hall; Shashi B. Verma; Raymond L. Desjardins; Peter M. Schuepp; J. Ian MacPherson

1997-01-01

260

Predicting equilibrium vegetation responses to global climate change using coupled biogeography and ecosystem models  

Microsoft Academic Search

Much current uncertainty surrounding the sensitivity to climatic change of natural vegetation in the USA is related to widely-varying approaches taken in constructing simulation models. Our goal was to reduce this uncertainty by coupling the biogeography model MAPSS (Mapped Atmosphere-Plant-Soil System) with critical ecosystem processes as simulated by TEM (Terrestrial Ecosystem Model). MAPSS predicts changes in leaf-area index (LAI) and

J. G. Borchers; R. P. Nielson

1995-01-01

261

[Characteristics of soil mineralizable carbon pool in natural restoration process of Karst forest vegetation].  

PubMed

By the method of taking space instead of time, an incubation test was conducted to study the characteristics of soil mineralizable carbon pool during the natural restoration of Karst forest vegetation in Maolan Nature Reserve, Guizhou Province of Southwest China. It was observed that the contents of soil total organic carbon (TOC) and mineralizable carbon (MC) as well as the carbon mineralization rate decreased with increasing soil depth but increased with the process of vegetation restoration. The amount of cumulative released carbon and the carbon release rate increased with the process of restoration, but the release rate decreased with increasing incubation time. The soil MC/TOC increased with the restoration process but had less change with increasing soil depth, while the qCO2 decreased with increasing soil depth and through the process of restoration. The soil MC had a negative correlation with the existing litter amount (r = -0.796) but positive correlation with the mass loss rate of the litter decomposition (r = 0.924). Soil habitat changed from strong interference at early stages to relative stability at late stages, and soil carbon sequestration changed from small capacity and strong potential at early stages to large capacity and weak potential at late stages. PMID:23189694

Huang, Zong-Sheng; Yu, Li-Fei; Fu, Yu-Hong

2012-08-01

262

Classification of Soil Moisture on Vegetated Earthen Levees Using X and L Band Synthetic Aperture Radar (SAR)  

NASA Astrophysics Data System (ADS)

Earthen levees protect large areas of land in the US from flooding. Timely inspection and repairs can reduce the potential for catastrophic failures. Changes in spatial and temporal patterns of soil moisture can reveal signs of instability and help identify zones of weakness. Since analytical and empirical models have shown a relationship between SAR backscatter and soil moisture, we are using SAR to classify soil moisture on levees. Estimation of soil moisture from SAR is challenging when the surface has any significant vegetation. For the levee application, the soil is typically covered with a uniform layer of grass. Our methodology is based on a supervised soil moisture classification using a back propagation neural network with four classes of low, medium, high, and very high soil moisture. Our methodology consists of the following steps: 1) segmentation of the levee area from background and exclusion of tree-covered areas; 2) extracting the backscattering and texture features such as GLCM (Grey-Level Co-occurrence Matrix) and wavelet features; 3) training the back propagation neural network classifier; and 4) testing the area of interest and validation of the results using ground truth data. Two sources of SAR imagery are tested with this method: (1) fully polarimetric L-band data from NASA's UAVSAR; and (2) dual-polarimetric X-band data from the German TerraSAR-X satellite. The study area is a 4 km stretch of levee along the lower Mississippi River in the United States. Field data collected simultaneously with image acquisition are utilized for training and validation. Preliminary results show classification accuracies of about 50% for the UAVSAR image and 30% for the TerraSAR-X image in vegetated areas. The figure below shows a soil moisture classification using UAVSAR on April 28, 2011.

Mahrooghy, M.; Aanstoos, J. V.; Hasan, K.; Nobrega, R. A.; Younan, N. H.

2011-12-01

263

CLASSIFICATION OF VEGETATION AND SOIL USING IMAGING SPECTROMETER DATA  

Microsoft Academic Search

Monitoring the Earth using imaging spectrometers has necessitated more accurate analyses and new applications to remote sensing. New algorithms have been developed for hyperspectral data classification lately, but also traditional classification algorithms have often been used. This study compares different classification algorithms for classification of vegetation using imaging spectrometer data. The test area located in southern Finland was imaged by

J. H. Lumme

264

Estimating vegetation parameter for soil erosion assessment in an alpine catchment by means of QuickBird imagery  

Microsoft Academic Search

Soil erosion rates in alpine regions are related to high spatial variability complicating assessment of risk and damages. A crucial parameter triggering soil erosion that can be derived from satellite imagery is fractional vegetation cover (FVC). The objective of this study is to assess the applicability of normalized differenced vegetation index (NDVI), linear spectral unmixing (LSU) and mixture tuned matched

K. Meusburger; D. Bänninger; C. Alewell

2010-01-01

265

Comparison of organochlorine pesticides and polychlorinated biphenyls residues in vegetables, grain and soil from organic and conventional farming in Poland  

Microsoft Academic Search

Organic and conventional crops were studied by identifying the relationship between persistent organic pollutants in cereals, vegetables and soil. The residues of organochlorine pesticides and polychlorinated biphenyls (PCBs) were determined in grains (rye and wheat), vegetables (carrots and beets) and soil collected from the fields. PCB residues recorded in the beets from organic farming were as high as 3.71 ppb

Agata Witczak; Hassan Abdel-Gawad

2012-01-01

266

Impact of Foot Traffic from Military Training on Soil and Vegetation Properties1  

Microsoft Academic Search

The impact of military training activities (primarily foot traffic) on soils and vegetation was assessed at the United States Air Force Academy, Colorado, USA. In May- June 1998 after 2 years of intensive training use, mean bulk densities of the top 6 cm of soil in the high-use site (1.37 g\\/cm3) and moderate-use site (1.30 g\\/cm3) were significantly different from

RANDY C. A. WHITECOTTON; MARK B. DAVID; ROBERT G. DARMODY; DAVID L. PRICE

2000-01-01

267

Influence of Vegetative Succession on Soil Chemistry of the Berkshires.  

National Technical Information Service (NTIS)

The study characterizes the chemistry of precipitation, canopy leaching, and stream water as well as analyzing soil properties in a series of successional forest stands in Northwestern Berkshire County, Massachusetts. Dramatic changes occur in the pH of p...

H. W. Art D. P. Dethier

1986-01-01

268

Spatial variability of soil and vegetation characteristics in an urban park in Tel-Aviv  

NASA Astrophysics Data System (ADS)

Mosaic-like spatial patterns, consisting of divers soil microenvironments, characterize the landscapes of many urban parks. These microenvironments may differ in their pedological, hydrological and floral characteristics, and they play important roles in urban ecogeomorphic system functioning. In and around a park covering 50 ha in Tel Aviv, Israel, soil properties and herbaceous vegetation were measured in eight types of microenvironments. Six microenvironments were within the park: area under Ceratonia siliqua (Cs-U), area under Ficus sycomorus (Fi-U), a rest area under F. sycomorus (Re-U), an open area with bare soil (Oa-S), an open area with biological crusts (Oa-C), and an open area with herbaceous vegetation (Oa-V). Outside the park were two control microenvironments, located, respectively, on a flat area (Co-P) and an inclined open area (Co-S). The soil was sampled from two depths (0-2 and 5-10 cm), during the peak of the growing season (March). For each soil sample, moisture content, organic matter content, CaCO3 content, texture, pH, electrical conductivity, and soluble ions contents were determined in 1:1 water extraction. In addition, prior to the soil sampling, vegetation cover, number of species, and species diversity of herbaceous vegetation were measured. The barbecue fires and visitors in each of the microenvironments were counted. Whereas the soil organic matter and vegetation in Fi-U differed from those in the control(Co-P, Co-S), those in Oa-V were similar to those in the control. Fi-U was characterized by higher values of soil moisture, organic matter, penetration depth, and vegetation cover than Cs-U. Open microenvironments within the park (Oa-S, Oa-C, Oa-V) showed lower values of soil penetration than the control microenvironments. In Oa-V unique types of plants such as Capsella bursa-pastoris and Anagallis arvensis, which did not appear in the control microenvironments, were found. This was true also for Fi-U, in which species like Oxalis pes-caprae were found. Significant differences in soil and vegetation properties were found between Re-U and the rest of microenvironments. Differences in levels of human activities, in addition to differences in vegetation types, increased the spatial heterogeneity of soil properties. The rest microenvironment (Re-U) exhibited degraded soil conditions and can be regarded as forming the fragile areas of the park. An urban park offers potential for presence and growth of natural vegetation and, therefore, also for preservation of biodiversity. Natural vegetation, in its role as a part of the urban park, enriches the landscape diversity and thereby may contribute to the enjoyment of the visitors in the park.

Sarah, Pariente; Zhevelev, Helena M.; Oz, Atar

2010-05-01

269

Reorganization of vegetation, hydrology and soil carbon after permafrost degradation across heterogeneous boreal landscapes  

NASA Astrophysics Data System (ADS)

The diversity of ecosystems across boreal landscapes, successional changes after disturbance and complicated permafrost histories, present enormous challenges for assessing how vegetation, water and soil carbon may respond to climate change in boreal regions. To address this complexity, we used a chronosequence approach to assess changes in vegetation composition, water storage and soil organic carbon (SOC) stocks along successional gradients within four landscapes: (1) rocky uplands on ice-poor hillside colluvium, (2) silty uplands on extremely ice-rich loess, (3) gravelly–sandy lowlands on ice-poor eolian sand and (4) peaty–silty lowlands on thick ice-rich peat deposits over reworked lowland loess. In rocky uplands, after fire permafrost thawed rapidly due to low ice contents, soils became well drained and SOC stocks decreased slightly. In silty uplands, after fire permafrost persisted, soils remained saturated and SOC decreased slightly. In gravelly–sandy lowlands where permafrost persisted in drier forest soils, loss of deeper permafrost around lakes has allowed recent widespread drainage of lakes that has exposed limnic material with high SOC to aerobic decomposition. In peaty–silty lowlands, 2–4 m of thaw settlement led to fragmented drainage patterns in isolated thermokarst bogs and flooding of soils, and surface soils accumulated new bog peat. We were not able to detect SOC changes in deeper soils, however, due to high variability. Complicated soil stratigraphy revealed that permafrost has repeatedly aggraded and degraded in all landscapes during the Holocene, although in silty uplands only the upper permafrost was affected. Overall, permafrost thaw has led to the reorganization of vegetation, water storage and flow paths, and patterns of SOC accumulation. However, changes have occurred over different timescales among landscapes: over decades in rocky uplands and gravelly–sandy lowlands in response to fire and lake drainage, over decades to centuries in peaty–silty lowlands with a legacy of complicated Holocene changes, and over centuries in silty uplands where ice-rich soil and ecological recovery protect permafrost.

Torre Jorgenson, M.; Harden, Jennifer; Kanevskiy, Mikhail; O’Donnell, Jonathan; Wickland, Kim; Ewing, Stephanie; Manies, Kristen; Zhuang, Qianlai; Shur, Yuri; Striegl, Robert; Koch, Josh

2013-09-01

270

RULE-BASED VEGETATION FORMATION MODEL FOR CANADA  

EPA Science Inventory

The Canadian Climate-Vegetation Model (CCVM) is a rule-based equilibrium model developed for the purpose of predicting the response of formation-level vegetation to climate and climate change. he CCVM relies on climatic parameters with an inferred mechanistic relationship to the ...

271

Modeling wetland vegetation using polarimetric SAR  

Microsoft Academic Search

Airborne polarimetric synthetic aperture radar (SAR) data are investigated for their potential in mapping herbaceous coastal wetlands. The subenvironments of coastal wetlands have very distinct vegetation cover and surface properties. Qualitative analysis of the SAR images reveals the relative importance of surface and vegetation scatter in these subenvironments. Furthermore, sampled SAR data distinctly separate the subenvironments, indicating that classification techniques

K. C. Slatton; M. M. Crawford; J. C. Gibeaut; R. Gutierrez

1996-01-01

272

MODELING STREAM CHANNEL ADJUSTMENT TO WOODY VEGETATION  

Technology Transfer Automated Retrieval System (TEKTRAN)

River restoration and bank stabilization programs often use vegetation for improving stream corridor habitat, aesthetic, and function. Yet no study has examined the use of managed vegetation plantings to transform a straight, degraded stream corridor into a more functional, aesthetically-pleasing m...

273

Interacting vegetative and thermal contributions to water movement in desert soil  

USGS Publications Warehouse

Thermally driven water-vapor flow can be an important component of total water movement in bare soil and in deep unsaturated zones, but this process is often neglected when considering the effects of soil-plant-atmosphere interactions on shallow water movement. The objectives of this study were to evaluate the coupled and separate effects of vegetative and thermal-gradient contributions to soil water movement in desert environments. The evaluation was done by comparing a series of simulations with and without vegetation and thermal forcing during a 4.7-yr period (May 2001-December 2005). For vegetated soil, evapotranspiration alone reduced root-zone (upper 1 m) moisture to a minimum value (25 mm) each year under both isothermal and nonisothermal conditions. Variations in the leaf area index altered the minimum storage values by up to 10 mm. For unvegetated isothermal and nonisothermal simulations, root-zone water storage nearly doubled during the simulation period and created a persistent driving force for downward liquid fluxes below the root zone (total net flux ~1 mm). Total soil water movement during the study period was dominated by thermally driven vapor fluxes. Thermally driven vapor flow and condensation supplemented moisture supplies to plant roots during the driest times of each year. The results show how nonisothermal flow is coupled with plant water uptake, potentially influencing ecohydrologic relations in desert environments. ?? Soil Science Society of America 5585 Guilford Rd., Madison, WI 53711 USA. All rights reserved.

Garcia, C. A.; Andraski, B. J.; Stonestrom, D. A.; Cooper, C. A.; Simunek, J.; Wheatcraft, S. W.

2011-01-01

274

Modelling soil anaerobiosis from water retention characteristics and soil respiration  

Microsoft Academic Search

Oxygen is a prerequisite for some and an inhibitor to other microbial functions in soils, hence the temporal and spatial distribution of oxygen within the soil matrix is crucial in soil biogeochemistry and soil biology. Various attempts have been made to model the anaerobic fraction of the soil volume as a function of structure, moisture content and oxygen consumption. Aggregate

Guy Schurgers; Peter Dörsch; Lars Bakken; Peter Leffelaar; Lars Egil Haugen

2006-01-01

275

Evaluation of a new model of aeolian transport in the presence of vegetation  

NASA Astrophysics Data System (ADS)

Aeolian transport is an important characteristic of many arid and semiarid regions worldwide that affects dust emission and ecosystem processes. The purpose of this paper is to evaluate a recent model of aeolian transport in the presence of vegetation. This approach differs from previous models by accounting for how vegetation affects the distribution of shear velocity on the surface rather than merely calculating the average effect of vegetation on surface shear velocity or simply using empirical relationships. Vegetation, soil, and meteorological data at 65 field sites with measurements of horizontal aeolian flux were collected from the Western United States. Measured fluxes were tested against modeled values to evaluate model performance, to obtain a set of optimum model parameters, and to estimate the uncertainty in these parameters. The same field data were used to model horizontal aeolian flux using three other schemes. Our results show that the model can predict horizontal aeolian flux with an approximate relative error of 2.1 and that further empirical corrections can reduce the approximate relative error to 1.0. The level of error is within what would be expected given uncertainties in threshold shear velocity and wind speed at our sites. The model outperforms the alternative schemes both in terms of approximate relative error and the number of sites at which threshold shear velocity was exceeded. These results lend support to an understanding of the physics of aeolian transport in which (1) vegetation's impact on transport is dependent upon the distribution of vegetation rather than merely its average lateral cover and (2) vegetation impacts surface shear stress locally by depressing it in the immediate lee of plants rather than by changing the bulk surface's threshold shear velocity. Our results also suggest that threshold shear velocity is exceeded more than might be estimated by single measurements of threshold shear stress and roughness length commonly associated with vegetated surfaces, highlighting the variation of threshold shear velocity with space and time in real landscapes.

Li, Junran; Okin, Gregory S.; Herrick, Jeffrey E.; Belnap, Jayne; Miller, Mark E.; Vest, Kimberly; Draut, Amy E.

2013-03-01

276

[Concentrations and distribution of tetracycline antibiotics in vegetable field soil chronically fertilized with manures].  

PubMed

Occurrence of antibiotics in the soils substantially fertilized with antibiotics-enriched animal manures is very of concern. This paper investigated the concentration and distribution of four tetracycline antibiotics in soils from vegetable field chronically fertilized with manures in subtropical area using solid-phase extraction followed by high-performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-MS/MS). The sum concentrations of four tetracycline compounds ranged from 1.35 microg/kg to 22.52 microg/kg with an average of 7.35 microg/kg. There were thirty one to one hundred percent of the soil samples were detected with average concentrations of 0.63- 3.11 microg/kg for four tetracycline compounds which dominated mostly with oxytetracycline and secondly with deoxytetracycline. Composition and levels of tetracycline compounds varied obviously in both horizontal and vertical soils. The concentration of tetracycline compounds in soil profile decreased rapidly with the depth and some of the compounds were still detected in 60 to 80 centimeter depth of soil. It is concluded that tetracycline antibiotics in soils from vegetable field chronically fertilized with manures in subtropical area were generally lower and less ecotoxic risk for soil ecosystem. But it should not be ignored in view of combined toxic effect and resistance of various compounds. PMID:21717767

Tai, Yi-Ping; Mo, Ce-Huij; Li, Yan-Wen; Wu, Xiao-Lian; Duan, Xia-Zhen; Qu, Xiang-Long; Huang, Xian-Pei

2011-04-01

277

[Spatial variation of heavy metals contamination in the soil and vegetables of Huludao City].  

PubMed

Hg, Pb, Cd, Zn, and Cu concentrations in the soil, vegetables and crop of Huludao city were investigated. The Hg, Pb, Cd, Zn, and Cu concentrations in soils of the smelting areas are 1.422, 443.1, 60.94, 4084, and 247.8 mg x kg(-1), thus 6.092, 3195, 341.7, 35 157, and 1 557 mg x kg(-1) for the maximal concentrations, respectively. Spatial distribution maps of heavy metals concentrations in top soils in Huludao City were separately laid out by using Kriging. Heavy metals spatial distribution patterns in soils show that Ph, Cd, Zn, Cu emissions from Huludao Zinc Plant are the main pollution sources of heavy metals to the top soils in Huludao City, but Hg emission from Huludao Zinc Plant and chlor-alkali industry is the main pollution source of mercury to the top soils. Heavy metals concentrations in top soils decrease exponentially with distance from the zinc smelting area. Except Hg, the exponential equation could be better to fit the variety forother heavy metals. Heavy metals in vegetable and crop cultivated around Huludao Zinc Plant are higher than from markets, suggests that heavy metals affect the local soil and crops seriously. PMID:19775010

Zheng, Na; Wang, Qi-Chao; Liu, Jing-Shuang; Wang, Yang; Zhang, Zhong-Sheng

2009-07-15

278

Genetic algorithm applied to a Soil-Vegetation-Atmosphere system: Sensitivity and uncertainty analysis  

NASA Astrophysics Data System (ADS)

Numerical models are of precious help for predicting water fluxes in the vadose zone and more specifically in Soil-Vegetation-Atmosphere (SVA) systems. For such simulations, robust models and representative soil hydraulic parameters are required. Calibration of unsaturated hydraulic properties is known to be a difficult optimization problem due to the high non-linearity of the water flow equations. Therefore, robust methods are needed to avoid the optimization process to lead to non-optimal parameters. Evolutionary algorithms and specifically genetic algorithms (GAs) are very well suited for those complex parameter optimization problems. Additionally, GAs offer the opportunity to assess the confidence in the hydraulic parameter estimations, because of the large number of model realizations. The SVA system in this study concerns a pine stand on a heterogeneous sandy soil (podzol) in the Campine region in the north of Belgium. Throughfall and other meteorological data and water contents at different soil depths have been recorded during one year at a daily time step in two lysimeters. The water table level, which is varying between 95 and 170 cm, has been recorded with intervals of 0.5 hour. The leaf area index was measured as well at some selected time moments during the year in order to evaluate the energy which reaches the soil and to deduce the potential evaporation. Water contents at several depths have been recorded. Based on the profile description, five soil layers have been distinguished in the podzol. Two models have been used for simulating water fluxes: (i) a mechanistic model, the HYDRUS-1D model, which solves the Richards' equation, and (ii) a compartmental model, which treats the soil profile as a bucket into which water flows until its maximum capacity is reached. A global sensitivity analysis (Morris' one-at-a-time sensitivity analysis) was run previously to the calibration, in order to check the sensitivity in the chosen parameter search space. For the inversion procedure a genetical algorithm (GA) was used. Specific features such as elitism, roulette-wheel process for selection operator and island theory were implemented. Optimization was based on the water content measurements recorded at several depths. Ten scenarios have been elaborated and applied on the two lysimeters in order to investigate the impact of the conceptual model in terms of processes description (mechanistic or compartmental) and geometry (number of horizons in the profile description) on the calibration accuracy. Calibration leads to a good agreement with the measured water contents. The most critical parameters for improving the goodness of fit are the number of horizons and the type of process description. Best fit are found for a mechanistic model with 5 horizons resulting in absolute differences between observed and simulated water contents less than 0.02 cm3cm-3 in average. Parameter estimate analysis shows that layers thicknesses are poorly constrained whereas hydraulic parameters are much well defined.

Schneider, Sébastien; Jacques, Diederik; Mallants, Dirk

2010-05-01

279

Variations in Soil Salinity and Riparian Vegetation Coverage as Indicators of Stress in an Arid Watershed  

NASA Astrophysics Data System (ADS)

Soil salinity and riparian vegetation coverages of an arid area in northern Mexico through time were investigated. The study area comprises a 10 km segment of the lower Rio Conchos and surrounding undeveloped, non-irrigated land. The amount of area affected by salinity and the type of salinity were determined using EC (electrical conductivity) in conjunction with satellite images and corroborated by field analysis. The soil salinity derived from the remote sensing data was tied to precipitation, greenness of vegetation and water level of a nearby reservoir. The most appropriate method to assess soil salinity was found to be the selective principal component (SPCA) technique of Chavez and Kwarteng while the techniques utilized to discriminate vigorously-growing vegetation were tasseled cap transformation and the normalized difference vegetation index (NDVI). With this region undergoing a severe drought for the last ten years, the response of different parts of the ecosystem and changes in vegetation that so closely affect wildlife and other natural resources in this area can be better evaluated.

Gutierrez, M.; Mickus, K.; Johnson, E.

2003-12-01

280

Contamination of vegetables, fruits and soil with geohelmints eggs on organic farms in Poland.  

PubMed

The objective of this study was to evaluate the contamination of vegetables, fruits and soil with zoonotic parasite eggs on organic and conventional farms in south-eastern Poland. To evaluate the contamination with eggs of zoonotic parasites, examinations were conducted on 8 conventional and 11 organic farms in south-eastern Poland from May-October in 2008 and 2009. The following fruit and vegetables were selected for the experiment: strawberry, leek, onion, carrot, zucchini, beetroot, parsley, potatoes, celery, rhubarb, lettuce, cabbage, broccoli, pumpkin, young beetroot leaves, cauliflower, French beans, turnip, fennel and sorrel. A total of 187 samples of vegetables, fruits and soil were examined by means of a modified flotation method according to Quinn et al. (1980). Contamination with Ascaris, Trichuris and Toxocara eggs was found, with a higher number of positive samples revealed on conventional (34.7%), compared to organic farms (18.9%). The level of contamination in soil samples from conventional farms was higher (88.5% positive samples), than of those from organic farms (32.8%). Of the 15 geohelmints eggs, positive samples were found in vegetables: 9 Toxocara eggs, 4 Ascaris eggs and 2 Trichuris eggs. No geohelmints eggs were observed in the strawberry samples. The consumption of vegetables and fruits contaminated with the eggs of parasites may be the cause of parasitoses in humans. Stricter sanitary standards on farms of all types may limit the incidence of parasitic zoonoses. PMID:23020033

K?ape?, Teresa; Borecka, Anna

2012-01-01

281

Variational estimation of soil and vegetation turbulent transfer and heat flux parameters from sequences of multisensor imagery  

NASA Astrophysics Data System (ADS)

Turbulent heat fluxes from the surface do not have a unique signature that can be detected by remotely deployed instruments. In order to retrieve the fluxes, the measurements need to be merged into models that infer fluxes from their space and time patterns. This study is based on variational assimilation of land surface temperature (LST) into a surface energy balance model with dual-source soil and vegetation flux components. There are two major unknown parameters in the estimation of land evaporation: near-surface air turbulent conductivity (that scales the magnitude of the fluxes) and evaporative fraction (that partitions the total flux into latent and sensible heat flux). This study advances the data assimilation approach in two major new directions. First and foremost, it recasts the variational assimilation system as a multiscale problem with LST estimates from a constellation of satellites. The assimilation system can ingest measurements with varying scales and overlapping coverages. Second, the remotely sensed LST is treated as a combination of contributions from the canopy and the exposed soil surface. Application to a large area within the U.S. Great Plains is shown. Spatial patterns of the retrieved parameters, their correspondence to observed land use maps, and their consistency with seasonal phenology are demonstrated. Finally, the performance of a combined-source formulation is compared with the dual-source model. Remarkably, the spatial patterns of the heat transfer coefficient reflect dominant vegetation patterns, even though there was no vegetation index information used in the combined-source formulation.

Caparrini, Francesca; Castelli, Fabio; Entekhabi, Dara

2004-12-01

282

Two-Layer Model of Near-Surface Soil Drying for Time-Continuous Hydrologic Simulations  

Microsoft Academic Search

A two-layer soil water balance model is developed to provide an efficient and robust description of land surface dynamics in response to atmospheric evaporative events. Soil, vegetation, and atmosphere are coupled dynamically under the assumption that soil moisture profiles approximately preserve similarity during simultaneous atmospheric drying and gravity drainage. The exfiltration flux at the land surface in response to the

Stefano Orlandini

1999-01-01

283

Incorporating Hydraulic Lift into a Land Surface Model and Its Effects on Surface Soil Moisture Prediction  

Microsoft Academic Search

In comparison with the Oklahoma Atmospheric Surface-layer Instrumentation System (OASIS) measurements, the Simulator for Hydrology and Energy Exchange at the Land Surface (SHEELS), a multilayer soil hydrological model, simulates a much faster drying of the superficial soil layer (5 cm) for a densely vegetated area at the OASIS site in Norman, Oklahoma, under dry conditions. Further, the measured superficial soil

Diandong Ren; Ming Xue; Ann Henderson-Sellers

2004-01-01

284

Multiple equilibrium states and the abrupt transitions in a dynamical system of soil water interacting with vegetation  

NASA Astrophysics Data System (ADS)

In semi-arid areas, multiple equilibrium states of an ecosystem (e.g., grassland and desert) are found to coexist, and the transition from grassland to desert is often abrupt at the boundary. A simple ecosystem model is developed to provide the biophysical explanation of this phenomenon. The model has three variables: living biomass, wilted biomass, and soil wetness. The moisture index, which is the ratio of the annual precipitation to potential evaporation, is the only external climate driving force, and the key mechanism is the vegetation-soil interaction. It is found that the maintenance of a grassland requires a minimum moisture index, and the abrupt transition occurs when the moisture index is around this critical value. These results are robust within a wide range for most model parameters, suggesting that the model may be applicable to other temperate grasslands. The characteristics of the wilted biomass also strongly influence the ecosystem's dynamics.

Zeng, Xiaodong; Shen, Samuel S. P.; Zeng, Xubin; Dickinson, Robert E.

2004-03-01

285

Effects of vegetation on radon transport processes in soil  

SciTech Connect

Radon concentrations in soil gas were measured on a weekly schedule. Samples were extracted through the tubes used for measuring pressure differentials at depths of 30, 100, 180 cm. From November to March, the concentrations increase with depth and are for the most part constant over time. The situation is similar from May through August. There is a pronounced increase in the soil radon concentration in early March. This is followed by a decrease to pre March levels at 30 cm. However, at 100 and 180 cm the radon concentrations remain elevated. Attempts were made to explain this data. The average soil moisture content measured with the neutron gauge are shown in Figure 2. Also shown is a history of precipitation events. The period from November to March was relatively dry. On March 6 there was a heavy rain deposited 3 cm of water. This was followed by a snow storm that contained over 5 cm of moisture. Precipitation events during the summer months did not seem to have a large effect on the moisture profile because these rainfall events are typical of short duration with a large amount of runoff. Other soil parameters and meteorological data were analyzed in order to determine their influence on soil radon concentrations.

Borak, T.B.

1991-02-01

286

Sensitivity to microwave measurements to vegetation biomass and soil moisture content: a case study  

Microsoft Academic Search

A comparative evaluation of the potential of active and passive microwave sensors in estimating vegetation biomass and soil moisture content is carried out. For this purpose, experimental data collected on an agricultural area by airborne scatterometers and radiometers during the AGRISCATT and AGRIRAD 1988 campaigns have been used. The results show that both microwave backscattering and emission are sensitive to

Paolo Ferrazzoli; Simonetta Paloscia; Paolo Pampaloni; Giovanni Schiavon; Domenico Solimini; Peter Coppo

1992-01-01

287

110mAg root and foliar uptake in vegetables and its migration in soil.  

PubMed

110mAg, as a radionuclide of corrosion products in water-cooled nuclear reactors, was detected in the liquid effluents of Guangdong Daya Bay Nuclear Power Station (GNPS) of Daya Bay under normal operation conditions. Experiments on a simulated terrestrial agricultural ecosystem were carried out using the pot experiment approach. The most common plants in Hong Kong and the South China vegetable gardens such as lettuce, Chinese spinach, kale, carrot, pepper, eggplant, bean, flowering cabbage, celery, European onion and cucumber were selected for (110m)Ag root and foliar uptake tests. The results show that carrot, kale and flowering cabbage have the greatest values of soil to plant transfer factor among the vegetables, while(110m)Ag can be transferred to Chinese spinach via foliar uptake. Flowering cabbage, the most popular leafy vegetable locally, could be used as a biomonitor for the radioisotope contamination in vegetables. Soil column and adsorption tests were also carried out to study the leaching ability and distribution coefficient (K(d)) of (110m)Ag in the soil. The results show that most of the radionuclide was adsorbed in the top 1 cm of soil regardless of the pH value. The K(d) was also determined. PMID:12573862

Shang, Z R; Leung, J K C

2003-01-01

288

Trace elements in vegetables grown on soils contaminated by base metal mining  

Microsoft Academic Search

Mining for lead and other base metals in England and Wales has left a legacy of heavy metal contamination of apparently productive fields and gardens in areas of prosperous and expanding towns. To assess whether vegetables grown on these soils absorb excessive quantities of heavy metals small experimental plots were established in northeast Wales and Derbyshire. Roots and aerial parts

Brian E. Davies; Helen M. White

1981-01-01

289

Structure, functions and interguild relationships of the soil nematode assemblage in organic vegetable production  

Technology Transfer Automated Retrieval System (TEKTRAN)

The abundance and metabolic footprints of soil nematodes were quantified during four of eight years of an intensive organic vegetable production system. Treatment variables included cover crop mixtures and frequency, and compost application rates. The abundances of bacterivore and fungivore nematode...

290

Joint field experiment of microwave and visible sensors for bare soil and vegetation and preliminary analysis  

Microsoft Academic Search

A joint field experiment was carried out using microwave and visible sensors for bare soil and vegetation in Shunyi of Beijing in May 2001. The sensors include a microwave radiometer, microwave scatterometer and visible and infrared spectrometer. The microwave radiometer operates in the L, C and K band with H and V polarizations. The microwave scatterometer operates in the C

Chao Wang; Weiguo Zhang; Hong Zhang; Ziqi Guo; Jianjun Ge; Kai Zhao; Baojiang Liu; Hang Dong

2002-01-01

291

Inversion of Soil Moisture Profiles Under Tall Vegetation with Low-Frequency Radar: Theory and Experiment  

Microsoft Academic Search

Simultaneous estimation of deep and shallow soil moisture will provide a major breakthrough for estimation of key unobserved hydrologic fluxes, evapotranspiration and acquifer recharge, linking surface hydrologic processes with those in the subsurface. Given that more than 35% of the global land surface is covered with substantial vegetation cover, exceeding 50 tons\\/ha, it is also imperative that the capability to

Mahta Moghaddam; Yuriy Goykhman

292

Rangeland Vegetation and Soil Response to Summer Patch Fires Under Continuous Grazing  

Microsoft Academic Search

Prescribed fire is used to reduce woody plant and cactus cover and restore degraded rangelands in the southern Great Plains, but little is known regarding the impact of summer fires. We evaluated the effects of summer fires applied as patch burns in continuously grazed rangeland in north Texas. Vegetation and soil responses were measured on patches burned within grazing units

W. Richard Teague; Sara E. Duke; J. Alan Waggoner; Steve L. Dowhower; Shannon A. Gerrard

2008-01-01

293

Radiostrontium contamination of soil and vegetation within the Semipalatinsk test site  

Microsoft Academic Search

The Semipalatinsk nuclear test site (STS) in the Republic of Kazakhstan was an important site for testing atomic bombs and other civil and military nuclear devices of the former Soviet Union. Results are presented from investigations on the extent of radiostrontium contamination in soils and vegetation at the technical areas of the STS, where the tests were conducted and in

B. J. Howard; N. Semioschkina; G. Voigt; M. Mukusheva; J. Clifford

2004-01-01

294

Uptake of Explosives from Contaminated Soil by Existing Vegetation at the Iowa Army Ammunition Plant.  

National Technical Information Service (NTIS)

This study examines the uptake of explosives by existing vegetation growing in soils contaminated with 2,4,6-trinitrotoluene (TNT) and 1,3,5-trinitro-1,3,5-triazine (RDX) in three areas at the Iowa Army Ammunition Plant (IAAP). To determine explosives upt...

J. F. Schneider S. D. Zellmer N. A. Tomczyk J. R. Rastorfer D. Chen

1995-01-01

295

PCDD and PCDF in air, soil, vegetation and oily runoff from a tire fire  

Microsoft Academic Search

In early February 1990, vandals set fire to a used tire storage facility near Hagersville, Ontario, Canada, During the fire, the Ontario Ministry of Environment and Energy (MOEE) monitored the site and surrounding impact zone for numerous organic contaminants. Samples of air, soil, vegetation, runoff water, and oily residue were collected and analyzed for polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans

Peter J. Steer; Colleen H. M. Tashiro; William D. Mcillveen; Ray E. Clement

1995-01-01

296

Microbial Communities in Cerrado Soils under Native Vegetation Subjected to Prescribed Fires and Under Pasture  

EPA Science Inventory

The objective of this work was to evaluate the effects of fire regimes and vegetation cover on the structure and dynamics of soil microbial communities, through phospholipid fatty acid (PLFA) analysis. Comparisons were made between native areas with different woody covers ("cerra...

297

Utilization of Crawfish Peeling Plant Waste as a Soil Amendment for Vegetable Crop Production.  

National Technical Information Service (NTIS)

Crawfish waste applied at proper rates to vegetable crops will provide many of the essential nutrients required for growth and production. The crop response is influenced by rates of application and by the type of crop. The soil analysis reveals definite ...

R. Barry

1980-01-01

298

A three-tiered approach for coupled vegetation and soil sampling to develop ecological descriptions  

Technology Transfer Automated Retrieval System (TEKTRAN)

Ecological site descriptions (ESDs), alongside similar land classification systems, are used to describe the breadth of plant community types, community changes, and soil surface conditions that can occur within a particular land area. Vegetation dynamic processes and management may change the ident...

299

Accumulation of cadmium and zinc in soil and vegetation from long-term application of wastewater  

Microsoft Academic Search

The accumulation of Cd and Zn in soils and vegetation irrigated with treated sewage effluents was examined at 3 locations in southern California. The Whittier Narrows site, a groundwater recharge test plot, received secondary effluent through intermittent flooding for approximately 14 years. Fountain Valley, a forested site, was flood irrigated with both primary and secondary effluents for 16 years. The

D. C. Hill; B. H. Olson; M. G. Rigby

1981-01-01

300

FLUE GAS DESULFURIZATION SLUDGE: ESTABLISHMENT OF VEGETATION ON PONDED AND SOIL-APPLIED WASTE  

EPA Science Inventory

The report gives results of research to identify and evaluate forms of vegetation and methods of their establishment for reclaiming retired flue gas desulfurization sludge ponds. Also studied were the soil liming value of limestone scrubber sludge (LSS) and plant uptake and perco...

301

Soil and groundwater chemistry and vegetation distribution in a desert playa, Owens Lake, California  

Microsoft Academic Search

Generation of fine particulate dust (PM10)from the Owens Lake play a creates a severe air pollution hazard in the western Great Basin of the United States. One proposed mitigation strategy involves establishment of native vegetation to stabilize and trap fugitive sand. This study investigated soil and groundwater chemistry and the distribution of native plant species in relation to salts and

R. A. Dahlgren; J. H. Richards; Z. Yu

1997-01-01

302

Marsh vegetation patterns and soil phosphorus gradients in the Everglades ecosystem  

Microsoft Academic Search

In order to test the hypothesis that phosphorous enrichment is modifying Everglades marsh community composition, we sampled vegetation and soil phosphorus concentrations along four transects in areas representative of varying environmental conditions within the Everglades region. Each transect originated at or near a canal flow control structure and extended towards the center of the marsh because the canal flow structures

Robert F. Doren; Thomas V. Armentano; Louis D. Whiteaker; Ronald D. Jones

1997-01-01

303

Relationships between soil microbial communities and soil carbon turnover along a vegetation and moisture gradient in interior Alaska  

NASA Astrophysics Data System (ADS)

Boreal landscapes are characterized by a mosaic of uplands and lowlands, which differ in plant species composition, litter biochemistry, and biogeochemical cycling rates. Boreal ecosystems, from upland black spruce stands to lowland fens, are structured largely by water table position and contain quantitatively and qualitatively different forms of soil organic matter. Differences in carbon (C) availability among ecosystems likely translate to differences in the structure of soil microbial communities, which in turn could affect rates of organic matter decomposition and turnover. We examined relationships between microbial communities and soil C turnover in near-surface soils along a topographic soil moisture and vegetation gradient in interior Alaska. We tested the hypothesis that upland black spruce sites would be dominated by soil fungi and have slow rates of C turnover, whereas lowland ecosystems would be dominated by bacteria and mesofauna (enchytraeids) and have more rapid rates of C turnover. We utilized several isotopic measures of soil C turnover including bomb radiocarbon techniques, the ?15N of SOM, and the difference between ?13C of SOM, DOC, and respired CO2. All three measures indicated greater C turnover rates in the surface soils of the lowland fen sites compared to the more upland locations. Quantitative PCR analyses of soil bacteria and archaea, combined with enchytraed counts, confirmed that surface soils from the lowland fen ecosystems had the highest abundances of these functional groups. Fungal biomass was highly variable and tended to be more abundant in the upland forest sites. Soil enzymatic results were mixed: potential cellulase activities were higher in the more upland soils even though rates of microbial activity were generally lower. Oxidative enzyme activities were higher in fens, even though these ecosystems are saturated and partly anaerobic. Overall our data support soil food web theory which argues that rapidly cycling systems are bacterial dominated with mesofaunal grazing, whereas slowly cycling systems have characteristic higher fungal:bacterial ratios.

Waldrop, M. P.; Harden, J. W.; Turetsky, M. R.; Petersen, D. G.; McGuire, A. D.; Briones, M. J.; Churchill, A. C.; Doctor, D. H.; Pruett, L. E.

2010-12-01

304

Identification and representability of processes controlling unsaturated flow in vegetated soils at differing temporal scales  

NASA Astrophysics Data System (ADS)

A model describing unsaturated flow in vegetated soil has been developed, coupling plant feedback mechanisms with a finite-difference implementation of Richards' equation. While care has been taken to relate all parameters and processes to physically realistic analogies, moderate uncertainty in a range of parameters is unavoidable due to the need for characterisation of pedo-transfer functions and the complexity of plant water processes. Confidence in model effectiveness has been addressed through simulations of lysimeter experiments undertaken at Imperial College. A highly comprehensive data set consists of measurements on eight lysimeters divided into two sets of four, with the two sets containing different soil types. The water table was maintained at 65 cm below the soil surface, and all possessed a mature crop of perennial ryegrass (Lolium perenne L.) by the start of the experiment. Measurements of soil hydrological status and onsite meteorological data were taken about every quarter of an hour for a period of close to a year, providing detailed information on events within the lysimeters, and the impact of various meteorological conditions over the year. Diurnal variation and seasonal responses are particularly clear. An application of sensitivity and uncertainty analysis to the model, using this detailed data set, has been undertaken. In the performance of the optimisation process, good quality of model definition at both diurnal and seasonal scales is treated as particularly important, as is the effect of measurement error on parameterisation at these different scales. Since we are correcting parameter estimates in the presence of measurement error, it is important to have an understanding of the distortions produced on the outputs by noise. Therefore, a Bayesian framework is used to facilitate the treatment of both measurement and parametric errors, and to allow the inclusion of subjective probability without losing mathematical rigour. Metropolis Hastings Monte-Carlo methods are used to approximate the posterior distribution for parameters of interest. Due to the complicated topology of the posterior probability, a range of different heuristic algorithms, including simulated annealing, has been investigated in order to aid the search for hard to find modes in which the posterior achieves substantial local maxima. Examination of such maxima aids in addressing questions of parameter and overall model identifiability.

Butler, A. P.; Jackson, B. M.

2003-04-01

305

INTERCOMPARISON OF ALTERNATIVE VEGETATION DATABASES FOR REGIONAL AIR QUALITY MODELING  

EPA Science Inventory

Vegetation cover data are used to characterize several regional air quality modeling processes, including the calculation of heat, moisture, and momentum fluxes with the Mesoscale Meteorological Model (MM5) and the estimate of biogenic volatile organic compound and nitric oxide...

306

Predicting equilibrium vegetation responses to global climate change using coupled biogeography and ecosystem models  

SciTech Connect

Much current uncertainty surrounding the sensitivity to climatic change of natural vegetation in the USA is related to widely-varying approaches taken in constructing simulation models. Our goal was to reduce this uncertainty by coupling the biogeography model MAPSS (Mapped Atmosphere-Plant-Soil System) with critical ecosystem processes as simulated by TEM (Terrestrial Ecosystem Model). MAPSS predicts changes in leaf-area index (LAI) and vegetation biome boundaries using a site water balance model in conjunction with a physiologically-conceived rule-base model. On the other hand, TEM simulates equilibrium fluxes and pools of carbon (C) and nitrogen (N) such as net primary productivity (NPP) and available N without redistributing vegetation. In the coupled version of MAPSS presented here, these hydrological and biogeochemical processes are mutually constrained. For example, N availability may limit maximum LAI, and therefore, site water balance. Alternatively, actual evapotranspiration and soil water availability may modulate NPP via photosynthesis and net N mineralization. Initial results with this TEM-coupled version of MAPSS reveal significantly different patterns of NPP and vegetation distribution for the conterminous USA compared to those from uncoupled models, particularly at thermal and hydric extremes.

Borchers, J.G.; Nielson, R.P. [Pacific Northwest Research Station, Corvallis, OR (United States)

1995-06-01

307

Quantitative assessment of vegetation cover and soil degradation factors within terrain units for planning, monitoring and assessment of renaturation along oil and gas pipelines  

Microsoft Academic Search

This paper evaluates the renaturation activities applying the quantification of vegetation cover (VC), the site suitability analysis (SSA) based on the predefined criteria (slope steepness category (SSC), soil erodibility factor (K) and VC) and soil erosion model (SEM) results within the terrain units (TUs) along pipeline rights-of-way (RoW). Quantification of VC percentage is performed to assess the overall restored VC

Emil Bayramov; Manfred Buchroithner; Eileen McGurty

2012-01-01

308

Growing up green on serpentine soils: Biogeochemistry of serpentine vegetation in the Central Coast Range of California  

USGS Publications Warehouse

Serpentine soils derived from the weathering of ultramafic rocks and their metamorphic derivatives (serpentinites) are chemically prohibitive for vegetative growth. Evaluating how serpentine vegetation is able to persist under these chemical conditions is difficult to ascertain due to the numerous factors (climate, relief, time, water availability, etc.) controlling and affecting plant growth. Here, the uptake, incorporation, and distribution of a wide variety of elements into the biomass of serpentine vegetation has been investigated relative to vegetation growing on an adjacent chert-derived soil. Soil pH, electrical conductivity, organic C, total N, soil extractable elements, total soil elemental compositions and plant digestions in conjunction with spider diagrams are utilized to determine the chemical relationships of these soil and plant systems. Plant available Mg and Ca in serpentine soils exceed values assessed in chert soils. Magnesium is nearly 3 times more abundant than Ca in the serpentine soils; however, the serpentine soils are not Ca deficient with Ca concentrations as high as 2235 mg kg-1. Calcium to Mg ratios (Ca:Mg) in both serpentine and chert vegetation are greater than one in both below and above ground tissues. Soil and plant chemistry analyses support that Ca is not a limiting factor for plant growth and that serpentine vegetation is actively moderating Mg uptake as well as tolerating elevated concentrations of bioavailable Mg. Additionally, results demonstrate that serpentine vegetation suppresses the uptake of Fe, Cr, Ni, Mn and Co into its biomass. The suppressed uptake of these metals mainly occurs in the plants' roots as evident by the comparatively lower metal concentrations present in above ground tissues (twigs, leaves and shoots). This research supports earlier studies that have suggested that ion uptake discrimination and ion suppression in the roots are major mechanisms for serpentine vegetation to tolerate the chemistry of serpentine soils. ?? 2008 Elsevier Ltd.

Oze, C.; Skinner, C.; Schroth, A. W.; Coleman, R. G.

2008-01-01

309

COMMENTARY - SPATIAL VARIATION OF SOIL PROPERTIES RELATING TO VEGETATION CHANGES  

Technology Transfer Automated Retrieval System (TEKTRAN)

Bekele and Hudnall provide an interesting perspective on the spatial variation of soil chemical properties in a natural area undergoing transition from prairie to forest. Their focus is on the unique calcareous prairie ecosystem of Louisiana where prairie remnants are being encroached upon by the f...

310

Investigations on Distribution of Copper in Soil, Vegetation and Soil Fauna of a Vineyard Ecosystem.  

National Technical Information Service (NTIS)

Investigations were carried through to test the effects of different copper contents in soils on soil fauna. The experiments were carried out in vineyards. Soil copper contents were correlated with the contents in invertebrates as earthworms, spiders, bee...

R. Wittassek

1987-01-01

311

Detecting vegetation-precipitation feedbacks in mid-Holocene North Africa from two climate models  

SciTech Connect

Using two climate-vegetation model simulations from the Fast Ocean Atmosphere Model (FOAM) and the Community Climate System Model (CCSM, version 2), we investigate vegetation-precipitation feedbacks across North Africa during the mid-Holocene. From mid-Holocene snapshot runs of FOAM and CCSM2, we detect a negative feedback at the annual timescale with our statistical analysis. Using the Monte- Carlo bootstrap method, the annual negative feedback is further confirmed to be significant in both simulations. Additional analysis shows that this negative interaction is partially caused by the competition between evaporation and transpiration in North African grasslands. Furthermore, we find the feedbacks decrease with increasing timescales, and change signs from positive to negative at increasing timescales in FOAM. The proposed mechanism for this sign switch is associated with the different persistent timescales of upper and lower soil water contents, and their interactions with vegetation and atmospheric precipitation.

Wang, Yi; Notaro, Michael; Liu, Zhengyu; Gallimore, Robert; Levis, Samuel; Kutzbach, John E.

2008-03-31

312

Detecting vegetation-precipitation feedbacks in mid-Holocene North Africa from two climate models  

NASA Astrophysics Data System (ADS)

Using two climate-vegetation model simulations from the Fast Ocean Atmosphere Model (FOAM) and the Community Climate System Model (CCSM, version 2), we investigate vegetation-precipitation feedbacks across North Africa during the mid-Holocene. From mid-Holocene snapshot runs of FOAM and CCSM2, we detect a negative feedback at the annual timescale with our statistical analysis. Using the Monte-Carlo bootstrap method, the annual negative feedback is further confirmed to be significant in both simulations. Additional analysis shows that this negative interaction is partially caused by the competition between evaporation and transpiration in North African grasslands. Furthermore, we find the feedbacks decrease with increasing timescales, and change signs from positive to negative at increasing timescales in FOAM. The proposed mechanism for this sign switch is associated with the different persistent timescales of upper and lower soil water contents, and their interactions with vegetation and atmospheric precipitation.

Wang, Y.; Notaro, M.; Liu, Z.; Gallimore, R.; Levis, S.; Kutzbach, J. E.

2008-03-01

313

Detecting vegetation-precipitation feedbacks in mid-Holocene North Africa from two climate models  

NASA Astrophysics Data System (ADS)

Using two climate-vegetation model simulations from the Fast Ocean Atmosphere Model (FOAM) and the Community Climate System Model (CCSM, version 2), we investigate vegetation-precipitation feedbacks across North Africa during the mid-Holocene. From mid-Holocene snapshot runs of FOAM and CCSM2, we detect a negative feedback at the annual timescale with our statistical analysis. Using the Monte-Carlo bootstrap method, the annual negative feedback is further confirmed to be significant in both simulations. Additional analysis shows that this negative interaction is partially caused by the competition between evaporation and transpiration in North African grasslands. Furthermore, we find the feedbacks decrease with increasing timescales, and change signs from positive to negative at increasing timescales in FOAM. The proposed mechanism for this sign switch is associated with the different persistent timescales of upper and lower soil water contents, and their interactions with vegetation and atmospheric precipitation.

Wang, Y.; Notaro, M.; Liu, Z.; Gallimore, R.; Levis, S.; Kutzbach, J. E.

2007-07-01

314

Spatio-temporal variability of soil moisture and its effect on vegetation in a desertified aeolian riparian ecotone on the Tibetan Plateau, China  

NASA Astrophysics Data System (ADS)

Soil moisture content is one of the limiting factors for natural vegetation succession. Soil moisture in the riparian ecotone showed strong spatial dependence. Precipitation and water level were the main determining environmental factors. The correlation between vegetation coverage and soil moisture increased with depth. The results have important implications for vegetation restoration on the Tibetan plateau.

Li, Haidong; Shen, Weishou; Zou, Changxin; Jiang, Jiang; Fu, Lina; She, Guanghui

2013-02-01

315

Concentrations of Radionuclides and Trace Elements in Soils and Vegetation Around the DARHT Facility during 2004  

SciTech Connect

Samples of soil, sediment, and unwashed overstory and understory vegetation were collected at four locations around the Dual-Axis Radiographic Hydrodynamic Test (DARHT) facility at Los Alamos National Laboratory (LANL). All samples were analyzed for concentrations of {sup 3}H, {sup 137}Cs, {sup 90}Sr, {sup 238}Pu, {sup 239,240}Pu, {sup 241}Am, {sup 234}U, {sup 235}U, {sup 238}U, Ag, As, Ba, Be, Cd, Cr, Cu, Hg, Ni, Pb, Sb, Se, and Tl. These results, which represent five years since the start of operations, were compared with baseline statistical reference level (BSRL) data established over a four-year-long preoperational period prior to DARHT operations, and to LANL and U.S. Environmental Protection Agency Screening Action Levels (SALs). Most radionuclides and trace elements in soil, sediment, and vegetation were below BSRL values and those soils/sediments that were above BSRLs were far below SALs.

P.R. Fresquez

2004-10-01

316

Numerical investigation of spatial pattern in a vegetation model with feedback function.  

PubMed

The vegetative cover in semi-arid lands typically occurs as patches of individual species more or less separated from one another by bare ground. Klausmeier [1999. Regular and irregular patterns in semiarid vegetation. Science 284 (5421), 1826-1828] reported that the vegetation striped patterns can grow lying along the contours of gentle slopes. He has proposed a model of vegetation stripes based on competition for water. In this paper, our main aim is to study the positive feedback effects between the water and biomass on the vegetation spatial pattern formation within a nonsaturated soil, which arises from the suction of water by the roots and processes of water resource redistribution. According to the dispersion relation formula, we discuss the changes of the wavelength, wave speed, as well as the conditions of the spatial pattern formation. Our numerical results show that trees are more sensitive than grasses to the positive feedback function to format the spatial heterogeneous pattern, and the stronger positive feedback increases the parameters region where vegetation bands occur, which indicates that the positive feedback raises the possibility of shift from green to desert states in semi-arid areas for the long term. Our numerical results also show that the positive feedback can increase the migration velocity of the vegetation stripes. PMID:18602122

Liu, Quan-Xing; Jin, Zhen; Li, Bai-Lian

2008-05-23

317

Critical state soil constitutive model for methane hydrate soil  

NASA Astrophysics Data System (ADS)

This paper presents a new constitutive model that simulates the mechanical behavior of methane hydrate-bearing soil based on the concept of critical state soil mechanics, referred to as the "Methane Hydrate Critical State (MHCS) model". Methane hydrate-bearing soil is, under certain geological conditions, known to exhibit greater stiffness, strength and dilatancy, which are often observed in dense soils and also in bonded soils such as cemented soil and unsaturated soil. Those soils tend to show greater resistance to compressive deformation but the tendency disappears when the soil is excessively compressed or the bonds are destroyed due to shearing. The proposed model represents these features by introducing five extra model parameters to the conventional critical state model. It is found that, for an accurate prediction of ground settlement, volumetric yielding plays an important role when hydrate soil undergoes a significant change in effective stresses and hydrate saturation, which are expected during depressurization for methane gas recovery.

Uchida, S.; Soga, K.; Yamamoto, K.

2012-03-01

318

Soil Heat Flow Model  

Microsoft Academic Search

The Penman-Monteith method for estimating evapotranspiration (ET) has been recommended by FAO. This method requires measures of temperature, wind speed, relative humidity and heat flow in the soil. This last variable is rarely available. Soil heat flow is generally small compared to the net radiation, and many times is ignored in the energy balance. Nevertheless, the addition or subtraction of

E. Varas; C. Nunez; F. J. Meza

2008-01-01

319

Biomarker patterns in present-day vegetation: consistency and variation - A study on plaggen soils  

NASA Astrophysics Data System (ADS)

Biomarker patterns in present-day vegetation are commonly used as proxies to reconstruct paleo-vegetation composition, land use history and to elucidate carbon cycling. Plaggen soils are formed by diverse vegetational inputs during century-long plaggen (i.e. sod) application associated with plaggen-agriculture on poor soils in north-western Europe. This resulted in remarkably stable organic matter. Plant source identification by biomarkers could provide insight in yet unknown stabilization mechanisms and the fate of organic matter upon ongoing land use change. The current rationale behind biomarker-based source identification is that patterns observed in present-day vegetation are generally representative with little random variation. However, our knowledge on variability and consistency of biomarker patterns is yet scarce. Therefore, to assess the applicability of biomarkers for source identification in plaggen soils, we analyzed published n-alkane and n-alcohol patterns of species and their various parts which contribute(d) input to plaggen soils. We considered shrubs, trees and grass species and evaluated rescaled patterns (i.e. relative abundances in chain-length range C17-36), odd-over-even predominance (OEP) and predominant n-alkanes. In addition, we explicitly looked into potential sources of systematic variation, e.g. spatial variation (climate, site conditions), temporal variation (seasonality, ontogeny) and laboratory methodology (extraction technique: washing/shaking, Soxhlet/ASE, saponification). We found meaningful clustering of n-alkanes C27, C29, C31 and C33, allowing for clear distinction of input by shrubs, trees and grasses to plaggen soils. Combination of these homologues with complete n-alkane patterns (C17-36) and OEP enabled further differentiation, while n-alcohols patterns were less distinct. Current limitation is the lack of extended and diverse quantitative records on biomarker patterns, especially for n-alcohols, non-leaf and belowground tissues, which hindered full statistical analysis. On species level we also recognized outliers and spreading. Systematic variation was indicated among tree species according to spatial conditions and by ontogeny. Yet, observed effects were ambiguous for other variation sources. This study highlights clear opportunities for application of biomarker patterns for source identification and elucidation of stabilization processes in (plaggen) soils. At the same time, application is challenged by systematic variation. Further research is key to quantify controls, magnitude and potential correction factors for such systematic variation. This would validate the use of n-alkane and n-alcohol patterns across broad spatial and temporal scales or identify boundaries wherein their consistency is ensured. Likely, these challenges apply to vegetation in a broad perspective, transcending plaggen vegetation, as assessment and application of present-day vegetation patterns is emerging.

Kirkels, Frédérique; Jansen, Boris; Kalbitz, Karsten

2013-04-01

320

Estimating soil water retention using soil component additivity model  

NASA Astrophysics Data System (ADS)

Soil water retention is a major soil hydraulic property that governs soil functioning in ecosystems and greatly affects soil management. Data on soil water retention are used in research and applications in hydrology, agronomy, meteorology, ecology, environmental protection, and many other soil-related fields. Soil organic matter content and composition affect both soil structure and adsorption properties; therefore water retention may be affected by changes in soil organic matter that occur because of both climate change and modifications of management practices. Thus, effects of organic matter on soil water retention should be understood and quantified. Measurement of soil water retention is relatively time-consuming, and become impractical when soil hydrologic estimates are needed for large areas. One approach to soil water retention estimation from readily available data is based on the hypothesis that soil water retention may be estimated as an additive function obtained by summing up water retention of pore subspaces associated with soil textural and/or structural components and organic matter. The additivity model and was tested with 550 soil samples from the international database UNSODA and 2667 soil samples from the European database HYPRES containing all textural soil classes after USDA soil texture classification. The root mean square errors (RMSEs) of the volumetric water content estimates for UNSODA vary from 0.021 m3m-3 for coarse sandy loam to 0.075 m3m-3 for sandy clay. Obtained RMSEs are at the lower end of the RMSE range for regression-based water retention estimates found in literature. Including retention estimates of organic matter significantly improved RMSEs. The attained accuracy warrants testing the 'additivity' model with additional soil data and improving this model to accommodate various types of soil structure. Keywords: soil water retention, soil components, additive model, soil texture, organic matter.

Zeiliger, A.; Ermolaeva, O.; Semenov, V.

2009-04-01

321

[Effects of vegetation coverage on spatial distribution of soil nematode trophic groups].  

PubMed

By the methods of classic statistics and geostatistics, this paper examined the spatial variability of soil nematodes and their trophic groups in bare and fallow plots at Shenyang Experimental Station of Ecology, Chinese Academy of Sciences. The results showed that soil pH had a negative effect on the plant-parasitic nematodes in both bare and fallow plots. The total number of soil nematodes was significantly higher in fallow than in bare plot, being 1 485.3 and 464.0 individuals per 100 g dry soil, respectively. The nugget (C0)/sill (C0 + C) ratio of total nematodes, plant-parasites and bacterivores were lower in fallow plot (27.3%-45.6%) than in bare plot (49.5%-100%). There was a significant difference in the spatial distribution of total nematodes and trophic groups between fallow and bare plots, indicating that vegetation coverage had an obvious effect on soil nematodes. PMID:16706057

Hua, Jianfen; Jiang, Yong; Liang, Wenju

2006-02-01

322

Comparison of Soil Hydraulic Parameterizations for Mesoscale Meteorological Models.  

NASA Astrophysics Data System (ADS)

Soil water contents, calculated with seven soil hydraulic parameterizations, that is, soil hydraulic functions together with the corresponding parameter sets, are compared with observational data. The parameterizations include the Campbell/Clapp-Hornberger parameterization that is often used by meteorologists and the van Genuchten/Rawls-Brakensiek parameterization that is widespread among hydrologists. The observations include soil water contents at several soil depths and atmospheric surface data; they were obtained within the Regio Klima Projekt (REKLIP) at three sites in the Rhine Valley in southern Germany and cover up to 3 yr with 10-min temporal resolution. Simulations of 48-h episodes, as well as series of daily simulations initialized anew every 24 h and covering several years, were performed with the “VEG3D” soil-vegetation model in stand-alone mode; furthermore, 48-h episodes were simulated with the model coupled to a one-dimensional atmospheric model. For the cases and soil types considered in this paper, the van Genuchten/Rawls-Brakensiek model gives the best agreement between observed and simulated soil water contents on average. Especially during episodes with medium and high soil water content, the van Genuchten/Rawls-Brakensiek model performs better than the Campbell/Clapp-Hornberger model.

Braun, Frank J.; Schädler, Gerd

2005-07-01

323

Classification of Coal Surface Mine Soil Material for Vegetation Management and Soil Water Quality.  

National Technical Information Service (NTIS)

An Alabama minesoil classification system was developed based on soil texture, soil color value and soil pH. Only five different soil classes were found in this study. However, the classification scheme allows for the inclusion of any minesoil that occurs...

E. S. Lyle P. A. Wood B. F. Hajek

1979-01-01

324

Rapid assessment of soil and groundwater tritium by vegetation sampling  

SciTech Connect

A rapid and relatively inexpensive technique for defining the extent of groundwater contamination by tritium has been investigated. The technique uses existing vegetation to sample the groundwater. Water taken up by deep rooted trees is collected by enclosing tree branches in clear plastic bags. Water evaporated from the leaves condenses on the inner surface of the bag. The water is removed from the bag with a syringe. The bags can be sampled many times. Tritium in the water is detected by liquid scintillation counting. The water collected in the bags has no color and counts as well as distilled water reference samples. The technique was used in an area of known tritium contamination and proved to be useful in defining the extent of tritium contamination.

Murphy, C.E. Jr.

1995-09-01

325

Methane uptake and nitrous oxide emission in Japanese forest soils and their relationship to soil and vegetation types  

Microsoft Academic Search

To determine the means and variations in CH4 uptake and N2O emission in the dominant soil and vegetation types to enable estimation of annual gases fluxes in the forest land of Japan, we measured monthly fluxes of both gases using a closed-chamber technique at 26 sites throughout Japan over 2 years. No clear seasonal changes in CH4 uptake rates were observed

Tomoaki Morishita; Tadashi Sakata; Masamichi Takahashi; Shigehiro Ishizuka; Takeo Mizoguchi; Yoshiyuki Inagaki; Kazuhiko Terazawa; Satoshi Sawata; Masanori Igarashi; Hiroshi Yasuda; Yasuhiro Koyama; Yoshihito Suzuki; Nobuyuki Toyota; Masamichi Muro; Masaru Kinjo; Hirokazu Yamamoto; Daitaro Ashiya; Yoichi Kanazawa; Tetsu Hashimoto; Hidetaka Umata

2007-01-01

326

Vegetation, soil property and climatic controls over greenhouse gas fluxes in a blanket peatland hosting a wind farm  

NASA Astrophysics Data System (ADS)

Peatlands are important carbon (C) stores, with boreal and subarctic peatlands containing 15-30 % of the world soil carbon stock (Limpens et al., 2008). Research has demonstrated that greenhouse gas (GHG) fluxes in peatlands are influenced by vegetation, soil property and climatic variables, including plant functional type (PFT), water table height and temperature. In this paper we present data from Black Law Wind Farm, Scotland, where we examined the effect of a predicted wind turbine-induced microclimatic gradient and PFT on carbon dioxide (CO2) and methane (CH4) fluxes. Moreover, we determined the role of vegetation, soil property and climatic variables as predictors of the variation in CO2 and CH4 emissions. We measured CO2 and CH4 at 48 plots within Black Law Wind Farm at monthly intervals from May 2011 to April 2012. Four sampling sites were located along a predicted wind turbine-induced microclimatic gradient. At each site four blocks were established, each with plots in areas dominated by mosses, sedges and shrubs. Plant biomass and PFT (vegetation factors); soil moisture, water table height, peat depth, C content, nitrogen (N) content and C:N (soil properties); and soil temperature and photosynthetically active radiation (PAR) (climatic variables) were measured. Analysis of variance (ANOVA) models based on the microclimatic gradient site, PFT and season when measurements were made explained 58 %, 44 % and 49 % of the variation in ecosystem respiration, photosynthesis and CH4, respectively. Site, PFT, season and their interactions were all significant for respiration and photosynthesis (with the exception of the PFT*site interaction) but for CH4 only the main effects were significant. Parsimonious ANOVA models using the biotic, soil property and climatic explanatory data explained 62 %, 55 % and 49 % of the variation in respiration, photosynthesis and CH4, respectively. Published studies (Baidya Roy and Traiteur 2010; Zhou et al., 2012) and preliminary results from this study suggest that a wind turbine-induced microclimatic effect may exist. Consequently, given that the climatic variables, factors influenced by changes in the climate, and their interactions affect GHG fluxes, the operational effects of wind farms on peatland ecosystems may need to be taken into account when considering their full life cycle carbon budget. Baidya Roy, S. and J. J. Traiteur (2010). Impacts of wind farms on surface air temperatures, Proceedings of the National Academy of Sciences, 109: 15679-15684. Limpens, J. et al. (2008). Peatlands and the carbon cycle: from local processes to global implications - a synthesis, Biogeosciences, 5(5): 1475-1491. Zhou, L., et al. (2012). Impacts of wind farms on land surface temperature, Nature Climate Change, 2: 539-543.

Armstrong, Alona; Waldron, Susan; Ostle, Nick; Whitaker, Jeanette

2013-04-01

327

Uptake of explosives from contaminated soil by existing vegetation at the Iowa Army Ammunition Plant  

SciTech Connect

This study examines the uptake of explosives by existing vegetation growing in soils contaminated with 2,4,6-trinitrotoluene (TNT) and 1,3,5-trinitro-3,5-triazine (RDX) in three areas at the Iowa Army Ammunition Plant (IAAP). To determine explosives uptake under natural environmental conditions, existing plant materials and soil from the root zone were sampled at different locations in each area, and plant materials were separated by species. Standard methods were used to determine the concentrations of explosives, their derivatives, and metabolites in the soil samples. Plant materials were also analyzed. The compound TNT was not detected in the aboveground portion of plants, and vegetation growing on TNT-contaminated soils is not considered a health hazard. However, soil and plant roots may contain TNT degradation products that may be toxic; hence, their consumption is not advised. The compound RDX was found in the tops and roots of plants growing on RDX-contaminated soils at all surveyed sites. Although RDX is not a listed carcinogen, several of its potentially present degradation products are carcinogens. Therefore, the consumption of any plant tissues growing on RDX-contaminated sites should be considered a potential health hazard.

Schneider, J.F.; Zellmer, S.D.; Tomczyk, N.A.; Rastorier, J.R.; Chen, D.; Banwart, W.L. [Argonne National Lab., IL (United States)

1995-02-01

328

Linking riparian dynamics and groundwater: an ecohydrologic approach to modeling groundwater and riparian vegetation.  

PubMed

The growing use of global freshwater supplies is increasing the need for improved modeling of the linkage between groundwater and riparian vegetation. Traditional groundwater models such as MODFLOW have been used to predict changes in regional groundwater levels, and thus riparian vegetation potential attributable to anthropogenic water use. This article describes an approach that improves on these modeling techniques through several innovations. First, evapotranspiration from riparian/wetland systems is modeled in a manner that more realistically reflects plant ecophysiology and vegetation complexity. In the authors' model programs (RIP-ET and PRE-RIP-ET), the single, monotonically increasing evapotranspiration flux curve in traditional groundwater models is replaced with a set of ecophysiologically based curves, one for each plant functional group present. For each group, the curve simulates transpiration declines that occur both as water levels decline below rooting depths and as waters rise to levels that produce anoxic soil conditions. Accuracy is further improved by more effective spatial handling of vegetation distribution, which allows modeling of surface elevation and depth to water for multiple vegetation types within each large model cell. The use of RIP-ET in groundwater models can improve the accuracy of basin scale estimates of riparian evapotranspiration rates, riparian vegetation water requirements, and water budgets. Two case studies are used to demonstrate that RIP-ET produces significantly different evapotranspiration estimates than the traditional method. When combined with vegetation mapping and a supporting program (RIP-GIS), RIP-ET also enables predictions of riparian vegetation response to water use and development scenarios. The RIP-GIS program links the head distribution from MODFLOW with surface digital elevation models, producing moderate- to high-resolution depth-to-groundwater maps. Together with information on plant rooting depths, these can be used to predict vegetation response to water allocation decisions. The different evapotranspiration outcomes produced by traditional and RIP-ET approaches affect resulting interpretations of hydro-vegetation dynamics, including the effects of groundwater pumping stress on existing habitats, and thus affect subsequent policy decisions. PMID:16222461

Baird, Kathryn J; Stromberg, Juliet C; Maddock, Thomas

2005-10-01

329

Test of Ecological Optimality for Semiarid Vegetation.  

National Technical Information Service (NTIS)

Three ecological optimality hypotheses which have utility in parameter reduction and estimation in a climate-soil-vegetation water balance model are reviewed and tested. The first hypothesis involves short term optimization of vegetative canopy density th...

G. D. Salvucci P. S. Eagleson E. K. Turner

1992-01-01

330

Modelling of Dynamic Soil Problems  

Microsoft Academic Search

Some possibilities for the modelling of dynamic soil problems are described. Two basic features of constitutive models to\\u000a be used in numerical analysis to simulate soil response under non-monotonic loading are: a description of the small strain\\u000a elastic behaviour which will evolve and develop its own anisotropies as the stress or strain history unfolds; and provision\\u000a for plasticity on reversal

David Muir Wood

331

Salmonella enterica serovar Typhimurium and Escherichia coli contamination of root and leaf vegetables grown in soils with incorporated bovine manure.  

PubMed

Bovine manure, with or without added Salmonella enterica serovar Typhimurium (three strains), was incorporated into silty clay loam (SCL) and loamy sand (LS) soil beds (53- by 114-cm surface area, 17.5 cm deep) and maintained in two controlled-environment chambers. The S. enterica serovar Typhimurium inoculum was 4 to 5 log CFU/g in manure-fertilized soil. The conditions in the two environmental chambers, each containing inoculated and uninoculated beds of manure-fertilized soil, simulated daily average Madison, Wis., weather conditions (hourly temperatures, rainfall, daylight, and humidity) for a 1 March or a 1 June manure application and subsequent vegetable growing seasons ending 9 August or 28 September, respectively. Core soil samples were taken biweekly from both inoculated and uninoculated soil beds in each chamber. Radishes, arugula, and carrots were planted in soil beds, thinned, and harvested. Soils, thinned vegetables, and harvested vegetables were analyzed for S. enterica serovar Typhimurium and Escherichia coli (indigenous in manure). After the 1 March manure application, S. enterica serovar Typhimurium was detected at low levels in both soils on 31 May, but not on vegetables planted 1 May and harvested 12 July from either soil. After the 1 June manure application, S. enterica serovar Typhimurium was detected in SCL soil on 7 September and on radishes and arugula planted in SCL soil on 15 August and harvested on 27 September. In LS soil, S. enterica serovar Typhimurium died at a similar rate (P >or= 0.05) after the 1 June manure application and was less often detected on arugula and radishes harvested from this soil compared to the SCL soil. Pathogen levels on vegetables were decreased by washing. Manure application in cool (daily average maximum temperature of <10 degrees C) spring conditions is recommended to ensure that harvested vegetables are not contaminated with S. enterica serovar Typhimurium. Manure application under warmer (daily average maximum temperature >20 degrees C) summer conditions is not recommended when vegetable planting is done between the time of manure application and late summer. A late fall manure application will not increase the risk of contaminating vegetables planted the next spring, since further experiments showed that repeated freeze-thaw cycles were detrimental to the survival of S. enterica serovar Typhimurium and E. coli in manure-fertilized soil. The number of indigenous E. coli in soil was never significantly lower (P < 0.05) than that of S. enterica serovar Typhimurium, suggesting its usefulness as an indicator organism for evaluating the risk of vegetable contamination with manure-borne S. enterica serovar Typhimurium. PMID:12039728

Natvig, Erin E; Ingham, Steven C; Ingham, Barbara H; Cooperband, Leslie R; Roper, Teryl R

2002-06-01

332

Salmonella enterica Serovar Typhimurium and Escherichia coli Contamination of Root and Leaf Vegetables Grown in Soils with Incorporated Bovine Manure  

PubMed Central

Bovine manure, with or without added Salmonella enterica serovar Typhimurium (three strains), was incorporated into silty clay loam (SCL) and loamy sand (LS) soil beds (53- by 114-cm surface area, 17.5 cm deep) and maintained in two controlled-environment chambers. The S. enterica serovar Typhimurium inoculum was 4 to 5 log CFU/g in manure-fertilized soil. The conditions in the two environmental chambers, each containing inoculated and uninoculated beds of manure-fertilized soil, simulated daily average Madison, Wis., weather conditions (hourly temperatures, rainfall, daylight, and humidity) for a 1 March or a 1 June manure application and subsequent vegetable growing seasons ending 9 August or 28 September, respectively. Core soil samples were taken biweekly from both inoculated and uninoculated soil beds in each chamber. Radishes, arugula, and carrots were planted in soil beds, thinned, and harvested. Soils, thinned vegetables, and harvested vegetables were analyzed for S. enterica serovar Typhimurium and Escherichia coli (indigenous in manure). After the 1 March manure application, S. enterica serovar Typhimurium was detected at low levels in both soils on 31 May, but not on vegetables planted 1 May and harvested 12 July from either soil. After the 1 June manure application, S. enterica serovar Typhimurium was detected in SCL soil on 7 September and on radishes and arugula planted in SCL soil on 15 August and harvested on 27 September. In LS soil, S. enterica serovar Typhimurium died at a similar rate (P ? 0.05) after the 1 June manure application and was less often detected on arugula and radishes harvested from this soil compared to the SCL soil. Pathogen levels on vegetables were decreased by washing. Manure application in cool (daily average maximum temperature of <10°C) spring conditions is recommended to ensure that harvested vegetables are not contaminated with S. enterica serovar Typhimurium. Manure application under warmer (daily average maximum temperature >20°C) summer conditions is not recommended when vegetable planting is done between the time of manure application and late summer. A late fall manure application will not increase the risk of contaminating vegetables planted the next spring, since further experiments showed that repeated freeze-thaw cycles were detrimental to the survival of S. enterica serovar Typhimurium and E. coli in manure-fertilized soil. The number of indigenous E. coli in soil was never significantly lower (P < 0.05) than that of S. enterica serovar Typhimurium, suggesting its usefulness as an indicator organism for evaluating the risk of vegetable contamination with manure-borne S. enterica serovar Typhimurium.

Natvig, Erin E.; Ingham, Steven C.; Ingham, Barbara H.; Cooperband, Leslie R.; Roper, Teryl R.

2002-01-01

333

Environmental controls and the influence of vegetation type, fine roots and rhizomorphs on diel and seasonal variation in soil respiration.  

PubMed

Characterization of spatial and temporal variation of soil respiration coupled with fine root and rhizomorph dynamics is necessary to understand the mechanisms that regulate soil respiration. A dense wireless network array of soil CO2 sensors in combination with minirhizotron tubes was used to continuously measure soil respiration over 1 yr in a mixed conifer forest in California, USA, in two adjacent areas with different vegetation types: an area with woody vegetation (Wv) and an area with scattered herbaceous vegetation (Hv). Annual soil respiration rates and the lengths of fine roots and rhizomorphs were greater at Wv than at Hv. Soil respiration was positively correlated with fine roots and rhizomorphs at Wv but only with fine roots at Hv. Diel and seasonal soil respiration patterns were decoupled with soil temperature at Wv but not at Hv. When decoupled, higher soil respiration rates were observed at increasing temperatures, demonstrating a hysteresis effect. The diel hysteresis at Wv was explained by including the temperature-dependent component of soil respiration and the variation dependent on photosynthetically active radiation. The results show that vegetation type and fine root and rhizomorph dynamics influence soil respiration in addition to changes in light, temperature and moisture. PMID:19086292

Vargas, Rodrigo; Allen, Michael F

2008-07-01

334

Environmental factors influencing soil testate amoebae in herbaceous and shrubby vegetation along an altitudinal gradient in subarctic tundra (Abisko, Sweden).  

PubMed

Shifts in community composition of soil protozoa in response to climate change may substantially influence microbial activity and thereby decomposition processes. However, effects of climate and vegetation on soil protozoa remain poorly understood. We studied the distribution of soil testate amoebae in herbaceous and shrubby vegetation along an altitudinal gradient (from below the treeline at 500 m to the mid-alpine region at 900 m a.s.l.) in subarctic tundra. To explain patterns in abundance, species diversity and assemblage composition of testate amoebae, a data set of microclimate and soil chemical characteristics was collected. Both elevation and vegetation influenced the assemblage composition of testate amoebae. The variation was regulated by interactive effects of summer soil moisture, winter soil temperature, soil pH and nitrate ion concentrations. Besides, soil moisture regulated non-linear patterns in species richness across the gradient. This is the first study showing the effects of winter soil temperatures on species composition of soil protozoa. The effects could be explained by specific adaptations of testate amoebae such as frost-resistant cysts allowing them to survive low winter temperatures. We conclude that the microclimate and soil chemical characteristics are the main drivers of changes in protozoan assemblage composition in response to elevation and vegetation. PMID:23022310

Tsyganov, Andrey N; Milbau, Ann; Beyens, Louis

2012-09-28

335

Land Surface Fluxes for Dynamic Vegetation Through Linkage of SVAT and Crop Models  

NASA Astrophysics Data System (ADS)

Accurate knowledge of energy and moisture fluxes at the land surface interface is important for predicting weather, near-term climate, and for vegetation growth and development. SVAT models are typically used to estimate these fluxes. However, estimating accurate fluxes during a growing season using SVAT models ia a major challenge due to lack of a sophisticated vegetation and development component. Recently efforts have been made to improve vegetation components in such models to simulate realistic fluxes. This study investigates linkage of an SVAT model, viz. Land Surface Process (LSP) model with a widely-tested crop-growth model, CERES-Maize, during a growing season of corn in North-Central Florida. The LSP model simulates one-dimensional coupled heat and moisture transport and provides the crop model with estimates of soil moisture and temperature profiles as well as heat fluxes. The CERES-Maize model simulates corn growth and development and provides the estimates of canopy characteristics such as LAI, biomass, root distribution, etc., to the LSP model. The aim of the linkage is not to make modifications to the architecture of the SVAT or the crop-growth models, but to create an interface so that the linkage is independent of the choice of SVAT and crop-growth model. Two main challenges in linking these models are the differences in the models' timesteps and spatial nodes. The CERES model uses a daily timestep, while the LSP model uses a much shorter one, as small as a few seconds. Also, the CERES model uses only 9 soil layers in the vadose zone, and the LSP model uses 130 nodes. The LSP-crop model was validated for weather and soil conditions in North-Central Florida using data from our sencond Microwave Water and Energy Balance Experiment (MicroWEX-2). MicroWEX-2 was an extensive field experiment conducted by the Center for Remote Sensing to monitor a growing season of corn from Day of Year (DoY) 78 to DoY 154 in 2004. During MicroWEX-2, we observed micrometeorological, soil, and vegetative conditions along with microwave signatures for a nine-acre field. The results of the model linkage will be presented.

Casanova, J. J.; Judge, J.

2005-12-01

336

The effect of the land cover\\/vegetation category on spatial and temporal soil moisture variation  

Microsoft Academic Search

Soil moisture is an important component of the hydrological cycle. The capability to observe soil moisture frequently and over large regions could significantly improve our ability to estimate some hydrological parameters such as infiltration, runoff, and soil wetness, which are very useful in hydrological modeling, real-time flooding forecast and irrigation management. The primary intent of this project was to map

H. Ghedira; N. Jahan; R. Khanbilvardi

2004-01-01

337

Persistence of poliovirus 1 in soil and on vegetables grown in soil previously flooded with inoculated sewage sludge or effluent.  

PubMed

Land disposal of sewage sludge and effluent is becoming a common practice in the United States. The fertilizer content and humus value of such wastes are useful for agricultural purposes, and the recycling of sewage onto the land eliminates many of our stream pollution problems. The potential exists for crops grown in such irrigated soil to be contaminated by viruses that may be present in the sewage. Studies were initiated to determine viral persistence in soil and on crops grown under natural conditions in field plots that had been flooded to a depth of 1 inch (2.54 cm) with poliovirus 1-inoculated sewage wastes. Lettuce and radishes were planted in sludge- or effluent-flooded soil. In one study, the vegetables were planted 1 day before flooding, and in another they were planted 3 days after the plots were flooded. Survival of poliovirus 1 in soil irrigated with inoculated sewage sludge and effluent was determined during two summer growing seasons and one winter period. The longest period of survival was during the winter, when virus was detected after 96 days. During the summer, the longest survival period was 11 days. Poliovirus 1 was recovered from the mature vegetables 23 days after flooding of the plots had ceased. Lettuce and radishes are usually harvested 3 to 4 weeks after planting. PMID:189685

Tierney, J T; Sullivan, R; Larkin, E P

1977-01-01

338

Uptake of explosives from contaminated soil by vegetation at the Joliet Army Ammunition Plant  

SciTech Connect

This study examines the uptake of explosives by vegetation growing on soils contaminated by 2,4,6-trinitrotoluene (TNT) in Group 61 at the Joliet Army Ammunition Plant (JAAP). Plant materials and soil from the root zone were sampled and analyzed to determine TNT uptake under natural field conditions. Standard USATHAMA methods were used to determine concentrations of explosives, their derivatives, and metabolites in the soil samples. No- explosives were detected in the aboveground portion of any plant sample. However, results indicate that TNT, 2-aminodinitrotoluene (2-ADNT), and/or 4-ADNT were present in some root samples. The presence of 2-ADNT and 4-ADNT increases the likelihood that explosives were taken up by plant roots, as opposed to their presence resulting from external soil contamination.

Schneider, J.F.; Tomczyk, N.A.; Zellmer, S.D. [Argonne National Lab., IL (United States); Banwart, W.L. [University of Illinois, Champaign-Urbana, IL (United States). Agronomy Dept.; Houser, W.P. [US Army Environmental Center, Edgewood, MD (United States)

1994-06-01

339

Modeling plant competition for soil water balance in Water-limited Mediterranean Ecosystems  

NASA Astrophysics Data System (ADS)

In heterogeneous ecosystems, such Mediterranean ecosystems, contrasting plant functional types (PFTs, e.g., grass and woody vegetation) compete for the water use. In these complex ecosystems current modeling approaches need to be improved due to a general lack of knowledge about the relationship between ET and the plant survival strategies for the different PFTs under water stress. Indeed, still unsolved questions are: how the PFTs (in particular the root systems) compete for the water use, the impact of this competition on the water balance terms, and the role of the soil type and soil depth in this competition. For this reasons an elaborated coupled Vegetation dynamic model (VDM) - land surface model (LSM) model able to also predict root distribution of competing plant systems is developed. The transport of vertical water flow in the unsaturated soil is modelled through a Richards’ equation based model. The water extraction (sink) term is considered as the root water uptake. Two VDMs predict vegetation dynamics, including spatial and temporal distribution/evolution of the root systems in the soil of two competing species (grass and woody vegetation). An innovative method for solving the unlinear system of predicting equations is proposed. The coupled model is able to predict soil and root water potential of the two competing plant species. The model is tested for the Orroli case study, situated in the mid-west of Sardinia within the Flumendosa river watershed. The site landscape is a mixture of Mediterranean patchy vegetation types: trees, including wild olives and coark oaks, different shrubs and herbaceous species. In particular two contrasting plant functional types (grass and woody vegetation) have been included. The model well predict the soil moisture and vegetation dynamics for the case study, and significantly different root potentials are predicted for the two PFTs, highlighting the root competition for the water use. The soil depth is low in the case study, while the Flumendosa basin is characterized by soils of different type and depth (more silty and deep nearly the river valley), such as typical in Mediterranean basins. A sensitivity analysis to the soil depth and soil type is performed for investigating their influences on the PFT dynamics and soil water balance. The influence of vegetation cover distribution of each plant type is also investigated. Results show that the plant compete differently according to site soil characteristics, and the impact of vegetation dynamics on the soil water balance terms is significant and cannot be neglected in current hydrological approaches.

Cortis, C.; Montaldo, N.

2009-12-01

340

Modeling vegetation reflectance from satellite and in-situ monitoring data  

NASA Astrophysics Data System (ADS)

Vegetation can be distinguished using remote sensing data from most other (mainly inorganic) materials by virtue of its notable absorption in the red and blue segments of the visible spectrum, its higher green reflectance and, especially, its very strong reflectance in the near-IR. Different types of vegetation show often distinctive variability from one another owing to such parameters as leaf shape and size, overall plant shape, water content, and associated background (e.g., soil types and spacing of the plants (density of vegetative cover within the scene). Different three-dimensional numerical models explicitly represent the vegetation canopy and use numerical methods to calculate reflectance. These models are computationally intensive and are therefore not generally suited to the correction of satellite imagery containing millions of pixels. Physically based models do provide understanding and are potentially more robust in extrapolation. They consider the vegetation canopy to comprise thin layers of leaves, suspended in air like sediment particles in water forming a turbid medium. Monitoring of vegetation cover changes by remote sensing data is one of the most important applications of satellite imagery. Vegetation reflectance has variations with sun zenith angle, view zenith angle, and terrain slope angle. To provide corrections of these effects, for visible and near-infrared light, was used a three parameters model and developed a simple physical model of vegetation reflectance, by assuming homogeneous and closed vegetation canopy with randomly oriented leaves. Multiple scattering theory was used to extend the model to function for both near-infrared and visible light. This vegetation reflectance model may be used to correct satellite imagery for bidirectional and topographic effects. For two ASTER images over Cernica forested area, placed to the East of Bucharest town , Romania, acquired within minutes from one another ,a nadir and off-nadir for band 3 lying in the near infra red, most radiance differences between the two scenes can be attributed to the BRDF effect. Must be considered also topographic corrections, as hill or mountain slopes affect the observed radiance of vegetation by modifying both the irradiance received by the vegetation and the vegetation reflectance. Model validation can be done based on spectral radiances in visible and infra-red wavelengths from satellite images and in-situ spectroradiometric measurements in some test forested areas. Based on satellite remote sensing data, can be mapped vegetation cover directly at local or regional scales from the apparent brightness measured in several spectral bands. The proposed model provides computationally efficient radiance corrections for varying sun and view zenith angles. It also provides a correction for the effect of terrain slope on vegetation reflectance, as a function of cosines of incidence and exitance angles. The proposed model can be applied for homogenous canopies over a wide range of sun zenith angles being analytically simple, facilitating rapid correction and applicable for both visible and near-infrared light. These attributes should make it for operational use in monitoring vegetation in temperate regions by remote sensing.

Zoran, Maria; Florin Zoran, Liviu; Ionescu Golovanov, Carmen; Dida, Adrian

2010-05-01

341

Changes in soils and vegetation in a Mediterranean coastal salt marsh impacted by human activities  

NASA Astrophysics Data System (ADS)

This paper reports changes in vegetation distribution and species cover in relation to soil factors and hydrology in a semiarid Mediterranean salt marsh adjacent to the Mar Menor saline lagoon. Species cover, soil salinity, and the groundwater level were monitored between 1991 and 1993 and between 2002 and 2004, and total organic carbon, total nitrogen, total phosphorus, nitrates, ammonium and exchangeable phosphorus were measured in the soils in both study periods. In addition, three soil profiles were described in August 1992 and August 2004. The results indicate an elevation of the water table throughout the 13-year period, which was attributable to water flowing from areas with intensive agriculture. Flooding increased and soil salinity dropped in the most saline sites and increased in the least saline ones. The morphology of the soil profiles reflected the increase in flooding periods, due to the appearance of a greyer matrix in the deeper horizons and a more diffuse pattern of Fe mottles. Following these environmental changes, Sarcocornia fruticosa, Phragmites australis and Juncus maritimus strongly expanded at the wettest sites, which led to the disappearance of the original zonation pattern. The cover of Limonium delicatulum, in turn, decreased with the increase in moisture but increased following the increase in salinity. Changes in soil nutrients were only very evident in the sandy soils of the beach, probably due to the influence of organic debris deposited on the shoreline by the storms and due to the strong increase in the colonisation of this habitat by perennial species. According to the results obtained, control measures are needed in order to preserve habitat diversity in this and other salt marshes of this area. Monitoring of the vegetation distribution could be a useful tool to identify environmental impacts, in order to implement remedial actions.

Álvarez-Rogel, J.; Jiménez-Cárceles, F. J.; Roca, M. J.; Ortiz, R.

2007-07-01

342

Seasonality in ENSO-related precipitation, river discharges, soil moisture, and vegetation index in Colombia  

NASA Astrophysics Data System (ADS)

An analysis of hydrologic variability in Colombia shows different seasonal effects associated with El Niño/Southern Oscillation (ENSO) phenomenon. Spectral and cross-correlation analyses are developed between climatic indices of the tropical Pacific Ocean and the annual cycle of Colombia's hydrology: precipitation, river flows, soil moisture, and the Normalized Difference Vegetation Index (NDVI). Our findings indicate stronger anomalies during December-February and weaker during March-May. The effects of ENSO are stronger for streamflow than for precipitation, owing to concomitant effects on soil moisture and evapotranspiration. We studied time variability of 10-day average volumetric soil moisture, collected at the tropical Andes of central Colombia at depths of 20 and 40 cm, in coffee growing areas characterized by shading vegetation ("shaded coffee"), forest, and sunlit coffee. The annual and interannual variability of soil moisture are highly intertwined for the period 1997-1999, during strong El Niño and La Niña events. Soil moisture exhibited greater negative anomalies during 1997-1998 El Niño, being strongest during the two dry seasons that normally occur in central Colombia. Soil moisture deficits were more drastic at zones covered by sunlit coffee than at those covered by forest and shaded coffee. Soil moisture responds to wetter than normal precipitation conditions during La Niña 1998-1999, reaching maximum levels throughout that period. The probability density function of soil moisture records is highly skewed and exhibits different kinds of multimodality depending upon land cover type. NDVI exhibits strong negative anomalies throughout the year during El Niños, in particular during September-November (year 0) and June-August (year 0). The strong negative relation between NDVI and El Niño has enormous implications for carbon, water, and energy budgets over the region, including the tropical Andes and Amazon River basin.

Poveda, GermáN.; Jaramillo, Alvaro; Gil, Marta MaríA.; Quiceno, Natalia; Mantilla, Ricardo I.

2001-08-01

343

[Effect of the vegetative cover on the biological activity of the soil of Chaco Arido].  

PubMed

Vegetation plays a primal role in arid ecosystems, since it creates microclimate conditions that moderate the characteristics of the region whereby the rational use of vegetal resources is fundamental. Felling, clearing and overgrazing lead to decrease in organic contribution and stimulate soil compaction, causing an alteration of microbial activity, with losses in nutrient turnover. The global biological activity is a soil parameter easy to obtain and indicates the presence and diversity of soil life as well as substrate availability and is useful in order to characterize soil potential fertility. This work was carried out in Natural Forest Reserve Chancaní, Province of Córdoba (Argentina), which is representative of Argentine Dry Chaco. Dominant tree species are: Prosopis flexuosa and Aspidosperma quebracho blanco. The global biological activity (GBA) was measured along one year, under trees, under shrubs and in interspaces. Soil samples were taken monthly from plots with four management systems: 1) forest, ii) selective clearing (only dominant species remain), iii) bush (clearing invaded by Larrea sp) and iv) grazing (cleared area, neither trees nor shrubs). GBA was evaluated using the CO2 release method, after ten days of incubation. It is concluded that in the plots with grasses and under the trees GBA was higher than with other treatments. The lesser GBA was detected in bushes and interspaces. All differences were more prominent during extreme temperature months. No significant difference between both species of dominant trees was observed. PMID:8210407

Abril, A; Acosta, M; Bachmeier, O; Rollan, A

1993-01-01

344

Herbaceous vegetation productivity, persistence, and metals uptake on a biosolids-amended mine soil  

SciTech Connect

The selection of plant species is critical for the successful establishment and long-term maintenance of vegetation on reclaimed surface mined soils. A study was conducted to assess the capability of 16 forage grass and legume species in monocultures and mixes to establish and thrive on a reclaimed Appalachian surface mine amended with biosolids. The 0.15-ha coarse-textured, rocky, non-acid forming mined site was prepared for planting by grading to a 2% slope and amending sandstone overburden materials with a mixture of composted and dewatered, anaerobically digested biosolids at a rate of 368 Mg ha{sup -1} (dry weight). The high rate of biosolids applied provided favorable soil chemical properties but could not overcome physical property limitations due to shallow undeveloped soil perched atop a compacted soil layer at 25 cm depth. The plant species whose persistence and biomass production were the greatest after a decade or more of establishment (i.e., switchgrass, sericea lespedeza, reed canarygrass, tall fescue, and crownvetch) shared the physiological and reproductive characteristics of low fertility requirements, drought and moisture tolerance, and propagation by rhizome and/or stolons. Of these five species, two (tall fescue and sericea lespedeza) are or have been seeded commonly on Appalachian coal surface mines, and often dominate abandoned pasture sites. Despite the high rates of heavy metal-bearing biosolids applied to the soil, plant uptake of Cd, Cu, Ni, and Zn were well within critical concentrations more than a decade after establishment of the vegetation.

Evanylo, G.K.; Abaye, A.O.; Dundas, C.; Zipper, C.E.; Lemus, R.; Sukkariyah, B.; Rockett, J. [Virginia Polytechnic Institute & State University, Blacksburg, VA (United States)

2005-10-01

345

Transfer of radioactivity from soil to vegetation in Rechna Doab, Pakistan  

Microsoft Academic Search

In Rechna Doab, samples of the most common vegetation, perennial grass Desmostachya bipinnata (dab), were collected along with soil samples from 29 sites. Natural radioactivity of Ra, Th\\/Ac and K was measured by using high purity germanium-based gamma ray spectrometer. Activity concentration levels of Ra, Th\\/Ac and K in soil were found to be 46.8±6.2 (36.0–57.6), 61.4±5.9 (48.2–73.2) and 644.8±73.9

Abdul Jabbar; Muhammad Tufail; Waheed Arshed; Arshed Salem Bhatti; Syed Salman Ahmad; Perveen Akhter; Muhammad Dilband

2010-01-01

346

An alternative modelling approach to predict emissions of N 2 O and NO from forest soils  

Microsoft Academic Search

Emissions of N2O from forest soils in Europe are an important source of global greenhouse gas emissions. However, influencing the emission\\u000a rates by forest management is difficult because the relations and feedbacks between forest and soils are complex. Process-based\\u000a models covering both vegetation and soil biogeochemical processes are frequently used to analyse emission patterns. Particularly,\\u000a the simulation of soil C

Arjan M. G. de Bruijn; Rüdiger Grote; Klaus Butterbach-Bahl

2011-01-01

347

Monitoring root-zone soil moisture through the assimilation of a thermal remote sensing-based soil moisture proxy into a water balance model  

Microsoft Academic Search

Two types of Soil Vegetation Atmosphere Transfer (SVAT) modeling approaches can be applied to monitor root-zone soil moisture in agricultural landscapes. Water and Energy Balance (WEB) SVAT modeling is based on forcing a prognostic root-zone water balance model with observed rainfall and predicted evapotranspiration. In contrast, thermal Remote Sensing (RS) observations of surface radiometric temperature (TR) are integrated into purely

Wade T. Crow; William P. Kustas; John H. Prueger

2008-01-01

348

Evaluating the dependence of vegetation on climate in an improved dynamic global vegetation model  

Microsoft Academic Search

The capability of an improved Dynamic Global Vegetation Model (DGVM) in reproducing the impact of climate on the terrestrial\\u000a ecosystem is evaluated. The new model incorporates the Community Land Model-DGVM (CLM3.0-DGVM) with a submodel for temperate\\u000a and boreal shrubs, as well as other revisions such as the “two-leaf” scheme for photosynthesis and the definition of fractional\\u000a coverage of plant functional

Xiaodong Zeng

2010-01-01

349

A method for climate and vegetation reconstruction through the inversion of a dynamic vegetation model  

Microsoft Academic Search

Climate reconstructions from data sensitive to past climates provide estimates of what these climates were like. Comparing\\u000a these reconstructions with simulations from climate models allows to validate the models used for future climate prediction.\\u000a It has been shown that for fossil pollen data, gaining estimates by inverting a vegetation model allows inclusion of past\\u000a changes in carbon dioxide values. As

Vincent Garreta; Paul A. Miller; Joël Guiot; Christelle Hély; Simon Brewer; Martin T. Sykes; Thomas Litt

2010-01-01

350

Modeling the Interactions Between River Morphodynamics and Riparian Vegetation  

NASA Astrophysics Data System (ADS)

The study of river-riparian vegetation interactions is an important and intriguing research field in geophysics. Vegetation is an active element of the ecological dynamics of a floodplain which interacts with the fluvial processes and affects the flow field, sediment transport, and the morphology of the river. In turn, the river provides water, sediments, nutrients, and seeds to the nearby riparian vegetation, depending on the hydrological, hydraulic, and geomorphological characteristic of the stream. In the past, the study of this complex theme was approached in two different ways. On the one hand, the subject was faced from a mainly qualitative point of view by ecologists and biogeographers. Riparian vegetation dynamics and its spatial patterns have been described and demonstrated in detail, and the key role of several fluvial processes has been shown, but no mathematical models have been proposed. On the other hand, the quantitative approach to fluvial processes, which is typical of engineers, has led to the development of several morphodynamic models. However, the biological aspect has usually been neglected, and vegetation has only been considered as a static element. In recent years, different scientific communities (ranging from ecologists to biogeographers and from geomorphologists to hydrologists and fluvial engineers) have begun to collaborate and have proposed both semiquantitative and quantitative models of river-vegetation interconnections. These models demonstrate the importance of linking fluvial morphodynamics and riparian vegetation dynamics to understand the key processes that regulate a riparian environment in order to foresee the impact of anthropogenic actions and to carefully manage and rehabilitate riparian areas. In the first part of this work, we review the main interactions between rivers and riparian vegetation, and their possible modeling. In the second part, we discuss the semiquantitative and quantitative models which have been proposed to date, considering both multi- and single-thread rivers.

Camporeale, C.; Perucca, E.; Ridolfi, L.; Gurnell, A. M.

2013-09-01

351

Large herbivores may alter vegetation structure of semi-arid savannas through soil nutrient mediation  

Microsoft Academic Search

In savannas, the tree–grass balance is governed by water, nutrients, fire and herbivory, and their interactions. We studied\\u000a the hypothesis that herbivores indirectly affect vegetation structure by changing the availability of soil nutrients, which,\\u000a in turn, alters the competition between trees and grasses. Nine abandoned livestock holding-pen areas (kraals), enriched by\\u000a dung and urine, were contrasted with nearby control sites

Cornelis van der Waal; Ada Kool; Seline S. Meijer; Edward Kohi; Ignas M. A. Heitkönig; Willem F. de Boer; Frank van Langevelde; Rina C. Grant; Mike J. S. Peel; Rob Slotow; Henrik J. de Knegt; Herbert H. T. Prins; Hans de Kroon

2011-01-01

352

Effect of nitrogen input on carbon accumulation of boreal forest soils and ground vegetation  

Microsoft Academic Search

The effects of nitrogen deposition on the carbon balance of forest soils and ground vegetation were estimated in long-term fertilization experiments. The experiments were established during 1958–1962. They were situated on 36- to 63-year-old Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies Karst.) stands of different levels of fertility. The experiments received nitrogen fertilization five to seven times

Raisa Mäkipää

1995-01-01

353

Impacts of Experimentally Applied Mountain Biking and Hiking on Vegetation and Soil of a Deciduous Forest  

Microsoft Academic Search

Many recent trail degradation problems have been attributed to mountain biking because of its alleged capacity to do more\\u000a damage than other activities, particularly hiking. This study compared the effects of experimentally applied mountain biking\\u000a and hiking on the understory vegetation and soil of a deciduous forest. Five different intensities of biking and hiking (i.e.,\\u000a 0, 25, 75, 200 and

EDEN THURSTON; RICHARD J. READER

2001-01-01

354

Effects of increasing periods under intensive arable vegetable production on biological, chemical and physical indices of soil quality  

Microsoft Academic Search

The effects on soil condition of increasing periods under intensive cultivation for vegetable production on a Typic Haplohumult\\u000a were compared with those of pastoral management using soil biological, physical and chemical indices of soil quality. The\\u000a majority of the soils studied had reasonably high pH, exchangeable cation and extractable P levels reflecting the high fertilizer\\u000a rates applied to dairy pasture

R. J. Haynes; R. Tregurtha

1999-01-01

355

Measurement of directional thermal infrared emissivity of vegetation and soils  

SciTech Connect

A new method has been developed for measuring directional thermal emissivity as a function of view angle for plant canopies and soils using two infrared thermometers each sensitive to a different wavelength band. By calibrating the two infrared thermometers to 0.1C consistency, canopy directional emissivity can be estimated with typical errors less than 0.005 in the 8--14 um wavelength band, depending on clarity of the sky and corrections for CO{sub 2} absorption by the atmosphere. A theoretical justification for the method is developed along with an error analysis. Laboratory measurements were used to develop corrections for CO{sub 2}, absorption and a field calibration method is used to obtain the necessary 0.1C consistency for relatively low cost infrared thermometers. The emissivity of alfalfa (LAI=2.5) and corn (LAI=3.2) was near 0.995 and independent of view angle. Individual corn leaves had an emissivity of 0.97. A wheat (LAI=3.0) canopy had an emissivity of 0.985 at nadir and 0.975 at 75 degree view angle. The canopy emissivity values tend to be higher than values in the literature, and are useful for converting infrared thermometer measurements to kinetic temperature and interpreting satellite thermal observations.

Norman, J.M. [Wisconsin Univ., Madison, WI (United States). Dept. of Soil Science; Balick, L.K. [EG and G Energy Measurements, Inc., Las Vegas, NV (United States)

1995-10-01

356

Soil and vegetation carbon stocks in Brazilian Western Amazonia: relationships and ecological implications for natural landscapes.  

PubMed

The relationships between soils attributes, soil carbon stocks and vegetation carbon stocks are poorly know in Amazonia, even at regional scale. In this paper, we used the large and reliable soil database from Western Amazonia obtained from the RADAMBRASIL project and recent estimates of vegetation biomass to investigate some environmental relationships, quantifying C stocks of intact ecosystem in Western Amazonia. The results allowed separating the western Amazonia into 6 sectors, called pedo-zones: Roraima, Rio Negro Basin, Tertiary Plateaux of the Amazon, Javari-Juruá-Purus lowland, Acre Basin and Rondonia uplands. The highest C stock for the whole soil is observed in the Acre and in the Rio Negro sectors. In the former, this is due to the high nutrient status and high clay activity, whereas in the latter, it is attributed to a downward carbon movement attributed to widespread podzolization and arenization, forming spodic horizons. The youthful nature of shallow soils of the Javari-Juruá-Purus lowlands, associated with high Al, results in a high phytomass C/soil C ratio. A similar trend was observed for the shallow soils from the Roraima and Rondonia highlands. A consistent east-west decline in biomass carbon in the Rio Negro Basin sector is associated with increasing rainfall and higher sand amounts. It is related to lesser C protection and greater C loss of sandy soils, subjected to active chemical leaching and widespread podzolization. Also, these soils possess lower cation exchangeable capacity and lower water retention capacity. Zones where deeply weathered Latosols dominate have a overall pattern of high C sequestration, and greater than the shallower soils from the upper Amazon, west of Madeira and Negro rivers. This was attributed to deeper incorporation of carbon in these clayey and highly pedo-bioturbated soils. The results highlight the urgent need for refining soil data at an appropriate scale for C stocks calculations purposes in Amazonia. There is a risk of misinterpreting C stocks in Amazonia when such great pedological variability is not taken into account. PMID:17846909

Schaefer, C E G R; do Amaral, E F; de Mendonça, B A F; Oliveira, H; Lani, J L; Costa, L M; Fernandes Filho, E I

2007-09-11

357

Simulation of soil temperature dynamics with models using different concepts.  

PubMed

This paper presents two soil temperature models with empirical and mechanistic concepts. At the test site (calcaric arenosol), meteorological parameters as well as soil moisture content and temperature at 5 different depths were measured in an experiment with 8 parcels realizing the combinations of the fertilized, nonfertilized, irrigated, nonirrigated treatments in two replicates. Leaf area dynamics was also monitored. Soil temperature was calculated with the original and a modified version of CERES as well as with the HYDRUS-1D model. The simulated soil temperature values were compared to the observed ones. The vegetation reduced both the average soil temperature and its diurnal amplitude; therefore, considering the leaf area dynamics is important in modeling. The models underestimated the actual soil temperature and overestimated the temperature oscillation within the winter period. All models failed to account for the insulation effect of snow cover. The modified CERES provided explicitly more accurate soil temperature values than the original one. Though HYDRUS-1D provided more accurate soil temperature estimations, its superiority to CERES is not unequivocal as it requires more detailed inputs. PMID:22792047

Sándor, Renáta; Fodor, Nándor

2012-06-18

358

Simulation of Soil Temperature Dynamics with Models Using Different Concepts  

PubMed Central

This paper presents two soil temperature models with empirical and mechanistic concepts. At the test site (calcaric arenosol), meteorological parameters as well as soil moisture content and temperature at 5 different depths were measured in an experiment with 8 parcels realizing the combinations of the fertilized, nonfertilized, irrigated, nonirrigated treatments in two replicates. Leaf area dynamics was also monitored. Soil temperature was calculated with the original and a modified version of CERES as well as with the HYDRUS-1D model. The simulated soil temperature values were compared to the observed ones. The vegetation reduced both the average soil temperature and its diurnal amplitude; therefore, considering the leaf area dynamics is important in modeling. The models underestimated the actual soil temperature and overestimated the temperature oscillation within the winter period. All models failed to account for the insulation effect of snow cover. The modified CERES provided explicitly more accurate soil temperature values than the original one. Though HYDRUS-1D provided more accurate soil temperature estimations, its superiority to CERES is not unequivocal as it requires more detailed inputs.

Sandor, Renata; Fodor, Nandor

2012-01-01

359

Impact of soil hydraulic parameter uncertainty on soil moisture modeling  

NASA Astrophysics Data System (ADS)

For simulations in basins where soil information is limited to soil type maps, a methodology is presented to quantify the uncertainty of soil hydraulic parameters arising from within-soil-class variability and to assess the impact of this uncertainty on soil moisture modeling. Continuous pedotransfer functions were applied to samples with different texture within each soil class to construct discrete probability distributions of the soil hydraulic parameters. When propagating the parameter distributions through a hydrologic model, a wide range of simulated soil moisture was generated within a single soil class. The pedotransfer function was found to play a crucial role in assessing the uncertainty in the modeled soil moisture, and the geographic origin of the pedotransfer function (region specific versus nonregion specific) highly affected the range and shape of the probability distribution of the soil hydraulic parameters. Furthermore, the modeled soil moisture distribution was found to be non-Gaussian. An accurate uncertainty assessment therefore requires the characterization of its higher-order moments. As an extension of this research, we have shown that applying continuous region-specific pedotransfer functions to the central point of a soil class is a better alternative to standard (often nonregion-specific) class pedotransfer functions for determining an average set of soil hydraulic parameters.

Loosvelt, Lien; Pauwels, Valentijn R. N.; Cornelis, Wim M.; de Lannoy, GabriëLle J. M.; Verhoest, Niko E. C.

2011-03-01

360

Impact of spruce forest and grass vegetation cover on soil micromorphology and hydraulic properties of organic matter horizon  

Microsoft Academic Search

Two organic matter horizons developed under a spruce forest and grass vegetation were chosen to demonstrate the impact of\\u000a a different vegetation cover on the micromorphology, porous system and hydraulic properties of surface soils. Micromorphological\\u000a studies showed that the decomposed organic material in the organic matter horizon under the grass vegetation was more compact\\u000a compared to the decomposed organic material

Radka Kodešová; Lenka Pavl?; Vít Kodeš; Anna Žigová; Antonín Nikodem

2007-01-01

361

Successional changes in soil and hyporheic nitrogen fertility on an alluvial flood plain: implications for riparian vegetation  

Microsoft Academic Search

In floodplain primary succession, vegetation colonizes nitrogen-poor alluvial deposits and fertility improves as soil nitrogen\\u000a accumulates over time. It is generally assumed that vegetation assimilates the vast majority of its nitrogen from the soil;\\u000a however, recent studies have suggested that the hyporheic zone also may be an important nitrogen source. We investigated the\\u000a potential relative importance of hyporheic nitrogen by

Michael R. Morris; Brook O. Brouwer; Jeremy K. Caves; Mary J. Harner; Jack A. Stanford

2010-01-01

362

Modelling the vegetation of China using the process-based equilibrium terrestrial biosphere model BIOME3  

Microsoft Academic Search

We model the potential vegetation and annual net primary production (NPP) of China on a 10 ' grid under the present climate using the processed-based equilibrium terrestrial biosphere model BIOME3. The simulated distribution of the vegetation was in general in good agreement with the potential natural vegetation based on a numerical comparison between the two maps using the ? V

JIAN NI; MARTIN T. SYKES; I. COLIN PRENTICE

2001-01-01

363

Mathematical modeling riparian vegetation zonation in semiarid conditions based on a transpiration index.  

NASA Astrophysics Data System (ADS)

Initially riparian vegetation modeling was focused on the study of ecological patches without taking into account the interactive effects of structures and processes in between them (Tabacchi et al., 1998). One of the greatest challenges, when carrying out a riparian ecosystem restoration, is to understand the physical and ecological processes of a system and the interaction and feedback within these processes. Jorde (2002) pointed out the importance of addressing complex linkages between processes and biotic interactions in research and in the development of restoration projects over larger spatial and temporal scales in the future. According to Tabacchi et al. (2000), the water cycle in riparian zones depends on three important relations: the water absorption by the plants, water storage and atmospherical return by evaporation. During recent years a variety of ecological models have taken into account the changes in the plant species as consequence of changes in the environmental variables and hydrological alterations (Baptist, 2005; Braatne et al., 2002; Glenz, 2005; Hooke et al., 2005; Murphy et al., 2006). Most of these models are based on functional relationships between river hydrology and vegetation species or communities. In semiarid regions we make the hypothesis transpiration will be one of the key factors determining the riparian vegetation presence and therefore, we will not consider in our model other factors as recruitment, flood damages, etc. The objectives of this work are: firstly to develop a model capable of simulating several riparian vegetation types which can be applied in a wide range of conditions across Mediterranean environments; and secondly to calibrate and to validate the model in several Mediterranean river stretches of the Iberian Peninsula, both in undisturbed and disturbed flow regimes. To achieve these objectives the following methodology has been applied. The model has been conceptualized as a static tank flow model based on the actual evapotranspiration of the riparian plants. This tank represents a portion of soil of the superficial root layer. The lower capacity limit of this tank is the permanent wilting moisture of the soil sample. On the other hand the upper capacity limit is the field capacity moisture. The tank's input flows are the precipitation, the root water rise and the capillary water rise. In contrast output flows are the actual evapotranspiration and the excess water of the tank. The most relevant model parameters are the soil retention curves, vegetation functional type parameters (specially related to root depths and the transpiration efficiency factors) and the daily hidro-meteorological data, which are water table elevation, precipitation and potential evapotranspiration. The model runs for a limited amount of vegetation functional types. In our simulations the following four functional types were used: Riparian Herbs; Riparian Juveniles and Small Scrubs, Riparian Trees and Big Shrubs; and Terrestrial Vegetation. The general model output variable is an evapotranspiration index based in the quotient between the current and the potential evapotranspiration. This index is used to determine the suitability of the simulated vegetation functional types to certain environmental conditions. Secondly, a sensitivity analysis was made for determining the most relevant model parameters. Finally the model has been calibrated and validated using as objective function a confusion matrix which compares the observed and the simulated riparian vegetation zonation. The calibration/validation processes have been carried out in seven study sites of the Jucar River Basin District. Four of those sites have a natural flow regime and three of them a regulated flow regime due to the presence of dams. Results have shown that the model is capable of providing effective simulations in compared to the observed riparian vegetation.

Real, Joaquin; Morales, Marco; Garcia, Alicia; Garofano, Virginia; Martinez-Capel, Francisco; Frances, Felix

2010-05-01

364

How sedge meadow soils, microtopography, and vegetation respond to sedimentation  

USGS Publications Warehouse

The expansion of urban and agricultural activities in watersheds of the Midwestern USA facilitates the conversion of species-rich sedge meadows to stands of Phalaris arundinacea and Typha spp. We document the role of sediment accumulation in this process based on field surveys of three sedge meadows dominated by Carex stricta, their adjacent Phalaris or Typha stands, and transitions from Carex to these invasive species. The complex microtopography of Carex tussocks facilitates the occurrence of other native species. Tussock surface area and species richness were positively correlated in two marshes (r2 = 0.57 and 0.41); on average, a 33-cm-tall tussock supported 7.6 species. Phalaris also grew in tussock form in wetter areas but did not support native species. We found an average of 10.5 Carex tussocks per 10-m transect, but only 3.5 Phalaris tussocks. Microtopographic relief, determined with a high-precision GPS, measured 11% greater in Carex meadows than Phalaris stands. Inflowing sediments reduced microtopographic variation and surface area for native species. We calculated a loss of one species per 1000 cm2 of lost tussock surface area, and loss of 1.2 species for every 10-cm addition of sediment over the sedge meadow surface. Alluvium overlying the sedge meadow soil had a smaller proportion of organic matter content and higher dry bulk density than the buried histic materials. We conclude that sedimentation contributes to the loss of native species in remnant wetlands. ?? 2002, The Society of Wetland Scientists.

Werner, K. J.; Zedler, J. B.

2002-01-01

365

Improving Space-borne Radiometer Soil Moisture Retrievals with Alternative Aggregation Rules for Ancillary Parameters in Highly Heterogeneous Vegetated Areas  

Technology Transfer Automated Retrieval System (TEKTRAN)

Retrieving soil moisture from space-borne microwave radiometer observations often requires ancillary parameters such as surface vegetation opacity or vegetation water content. The conventional approach for deriving representative footprint-scale values of these parameters is to simply average the co...

366

Soil Trace Gas Flux for Wetland Vegetation Zones in North Dakota Prairie Pothole Basins  

NASA Astrophysics Data System (ADS)

Wetland ecosystems are considered a source for radiatively trace gases [methane (CH4), carbon dioxide (CO2), nitrous oxide (N2O)] but flux data for these greenhouse gases are lacking for depressional wetlands that comprise the Prairie Pothole Region. This region is characterized by thousands of small, closed basins that extend along the Missouri Coteau from north central Iowa to central Alberta. Surrounding each body of water are conspicuous zonation patterns given by specific vegetation life-forms and soil properties that are predominately formed by basin hydrology. Basin vegetation zones include deep marsh, shallow marsh, wet meadow, low prairie, and cropland (Stewart and Kantrud,1971). Our primary objective was to determine if net greenhouse gas flux for soils in these wetland basins [mg/m2/day CO2 equivalent (IPCC, 2000)] vary with vegetative zone for prairie pothole ecosystems. These data may then be used to map estimates for total basin greenhouse gas (GHG) flux. Additionally, we aimed to find the relative contribution of each of the 3 trace gases (CO2, CH4 and N2O) to net GHG flux. We hypothesized that flux would be greatest for marsh areas and lowest for upland areas. We selected a semi-permenant prairie pothole research site in Max, ND and mapped respective vegetative zones for 3 adjacent basins. Sample points were randomly selected for each basin and zone using aerial imagery. Samples of soil gases were collected using the static chamber method on August 3, 2003, and these were analyzed using gas chromatography for CO2, CH4 and N2O the following day. Soil moisture, clay content, organic matter, and temperature data were also collected. Net greenhouse gas flux for the cropped zone soils was significantly lower (p<0.01) than flux for the deep marsh, shallow marsh and wet meadow zone soils. Average flux measurement by zone (mg CO2 equivalent/m2/day) was 283 for cropland, 677 for low prairie, 1067 for wet meadow, 2572 for shallow marsh, and 6686 for deep marsh. Methane, in terms of CO2 equivalents, contributed most strongly to and was the best predictor of greenhouse gas flux (r2=0.98). Since most of these basin areas are planted with wheat, average net GHG flux per square meter was 600 to 900 mg CO2 equivalents per day. Our results indicate that there are flux differences among wetland zones within these closed basin ecosystems and that CH4 contributes most to net GHG flux for these wetland soils.

Phillips, R. L.; Beeri, O.; Dekaiser, E. S.

2003-12-01

367

Biostimulation of natural microbial assemblages in oil-amended vegetated and desert sub-Antarctic soils.  

PubMed

A field study was initiated in December 2000 in two selected soils of The Grande Terre (Kerguelen Archipelago) with the objective of determining the long-term effects of fertilizer addition on the biodegradation rate and the toxicity of oil residues under severe sub-Antarctic conditions. Two soils were selected. The first site supports an abundant vegetal cover; the second one was desert soil, devoid of plant material. These two soils were located in the vicinity of the permanent station of Port-aux-Français (69 degrees 42'E; 49 degrees 19'S). A series of five experimental plots (0.75 x 0.75 m) were settled firmly into each of the studied soils. Each plot received 500 mL of diesel or Arabian light crude oil, and some of them were treated with a bioremediation agent: slow-release fertilizer Inipol EAP-22 (Elf Atochem). All the plots were sampled on a regular basis over a 1 year period. Heterotrophic and hydrocarbon-degrading microorganisms increased by two orders of magnitude during the first month of the experimentation in all treated enclosures, but differences appeared between the different plots. The microbial response was improved by bioremediation treatments. However, fertilizer addition had a greater impact on the desert soil when compared to the vegetated one. All chemical indices show a reduction of alkanes and light aromatics. Toxicity results show a high variability between treatments and environmental conditions. As a conclusion, it is clear that the microbial response was rapid and efficient in spite of the severe weather conditions, and the rate of degradation was improved by bioremediation treatments. However, after 1 year of treatment, the signal of a relatively high toxicity of oiled residues remained present in the two studied soils. PMID:14681739

Delille, D; Coulon, F; Pelletier, E

2003-12-18

368

Scale and Resolution Relationships of Soils Information with Hydrology Modeling  

NASA Astrophysics Data System (ADS)

Recent developments in digital soil mapping coupled with pedotransfer functions have improved significantly the ability of soil information to be provided quantitatively. This presents a challenge and an opportunity to understand the scale dependency of simulated hydrologic processes and their relation to the scale and spatial resolution of soil information. The objective of this research is to determine the sensitivity of hydrologic model simulations to the underlying spatial resolution of soils information in the context of different watersheds sizes. Hall Creek, a 56 km2 watershed in southern Indiana was the focus of this study. The majority of the soils in the watershed formed in loess over weathered sandstone, siltstone and shale. Sub-watersheds varying in size from less than 1km2 to 25km2 were delineated based on 5 m resolution DEM. Raster based soil maps at 5m resolution were first created using Terrain Attribute Soil Mapping (TASM) procedures. The soil maps were then used as an input to the Distributed Hydrology Vegetation Model (DHSVM) to predict stream flow from various sub-watersheds. In order to study the interaction between the aggregation level of soil information and watershed size, the pixel size for the DHSVM simulation was kept at 5m while the pixel size of the underlying soil maps was changed to 5, 10, 30 and 90m resolution. The DHSVM was calibrated for the Hall Creek watershed based on the 5m soil information and the USGS recorded stream discharge. The differences between predicted stream flows increased with decreasing resolution level of the soil information. The differences increased progressively as the sub-watersheds size decreased suggesting an interaction between watershed size and aggregation level of soil information. The magnitude of the predicted streamflow sensitivity can be used to determine the appropriate spatial resolution for digital soil mapping for hydrology applications, in relation to watershed size.

Libohova, Z.; Owens, P.; Bowling, L. C.; Cherkauer, K. A.; Naz, B. S.; Winzeler, E. H.

2009-12-01

369

Stochastic radiative transfer model for mixture of discontinuous vegetation canopies  

Microsoft Academic Search

Modeling of the radiation regime of a mixture of vegetation species is a fundamental problem of the Earth's land remote sensing and climate applications. The major existing approaches, including the linear mixture model and the turbid medium (TM) mixture radiative transfer model, provide only an approximate solution to this problem. In this study, we developed the stochastic mixture radiative transfer

Nikolay V. Shabanova; D. Huang; Y. Knjazikhina; Ranga B. Myneni

370

Fire as an interactive component of dynamic vegetation models  

Microsoft Academic Search

Fire affects ecosystems by altering both their structure and the cycling of carbon and nutrients. The emissions from fires represent an important biogeochemical pathway by which the biosphere affects climate. For climate change studies it is important to model fire as a mechanistic climate-dependent process in dynamic global vegetation models (DGVMs) and the terrestrial ecosystem components of climate models. We

Vivek K. Arora; George J. Boer

2005-01-01

371

Application of the Preisach Model to Soil-moisture Hysteresis  

NASA Astrophysics Data System (ADS)

An examination of the physics of the land phase of the hydrological cycle shows that the most important non-linearities occur in the unsaturated zone of the soil. These have been studied using switched boundary conditions applied to the one-dimensional form of Richards differential equation, modelling the wetting and drying of a column of bare or vegetated soil, at a scale of roughly one meter. However, the strongly non-linear hysteretic property of the soil moisture characteristic is usually ignored. Smooth non-linear differential, or integro-differential, operators cannot reproduce soil-moisture hysteresis. The classical Preisach Model is presented and applied to the quantitative description of soil-moisture scanning curves. The Preisach model is a deterministic, rate independent non-linear operator with return-point memory and congruent loops. Special, one parameter, classes of Preisach operators are proposed as models of soil-moisture hysteresis for particular soils. The results of fitting these operators to laboratory and field data, taken from the Grenoble GRIZZLY Soil Database, are presented and discussed.

O'Kane, J.; Pokrovskii, A.; Krejci, P.; Haverkamp, R.

2003-12-01

372

[Spatial heterogeneity of vegetation and soil characteristics in oasis-desert ecotone].  

PubMed

The spatial distribution of bio- and abiotic factors in ecosystem has the features of spatial heterogeneity in general, and spatial heterogeneity is important in the function and process of ecosystem at a variety of scales. In this paper, semivariance theory and methods were used to study the degree, composition, scale and pattern of spatial heterogeneity of vegetation coverage and soil environment factors, and their relationships in the Fukang oasis-desert ecotone of Xinjiang. With block kriging in the studied area of sampling, the spatial pattern of each factor was expressed in three dimensions as well. The results indicated that except the little spatial autocorrelation of salt salinity, there existed a spatial autocorrelation above mean of the other factors, and the spatial variation was mainly limited to smaller scales. The vegetation coverage, for which auto-correlated spatial heterogeneity was a main component, had a high degree of spatial heterogeneity with obvious spatial pattern at the scale of 3 km. From the perspective of spatial distributions, there existed a remarkable difference between soil holard and soil pH value in the studied area. Besides this, the higher value areas interleaved with the lower ones, significant positive correlations were observed between herbage coverage and soil factors (surface SH and SPH), and shrub coverage depended on the deep SH. The difference of spatial heterogeneity and pattern between SC and HC indicated the different ecological function and process in the ecosystem. PMID:12973993

Chen, Peng; Chu, Yu; Gu, Fengxue; Zhang, Yuandong; Pan, Xiaoling

2003-06-01

373

Technical note monitoring native vegetation on a dumpsite of PCB-contaminated soil.  

PubMed

Composition of native vegetation on a polychlorinated biphenyls (PCB)-contaminated soil dumpsite at Lhenice, South Bohemia (Czech Republic), was determined and species variability in the accumulation of PCBs in plant biomass was investigated. Soil stripping contaminated by PCBs originated at a factory producing electrical transformers that mostly used the commercial PCB mixture Delor 103 and 106. The PCB content of soil in the most contaminated part of the dumpsite reached 153 mg kg(-1) dry soil. Low diversity of plant species was found on the dumpsite. Results showed three grass species, Festuca arundinacea Schreb., Phalaroides arundinacea (L.) Rauschert., and Calamagrostis epigeios (L.) Roth., to be the major components of the vegetation and confirmed their high tolerance toward PCB contamination. The highest content of PCB in plant biomass--813.2 microg kg(-1) dry biomass--was determined in Festuca aboveground biomass. For phytoextraction purposes especially, Festuca can be recommended due to its high biomass yield, but its bioconcentration factor was very low (0.006). Tripleurospermum maritimum (L.) Sch. Bip. and Cirsium arvense (L.) Scop. grew mainly at the margins of the most contaminated part of the dumpsite. The PCB content determined in their aboveground biomass-278.7 and 289.5 microg kg(-1) dry biomass, respectively--was nonsignificantly lower compared to grass species Phalaroides and Calamagrostis. Salix (Salix viminalis L. and Salix caprea L.) was monitored among plant species composition at this site as a representative of woody species. PMID:18246716

Pavlíková, Daniela; Macek, Tomas; Macková, Martina; Pavlík, Milan

374

Land Abandonment in the Eastern Cape, South Africa: Implications for vegetation invasions, soil surface conditions and gully erosion  

NASA Astrophysics Data System (ADS)

Abandonment of cultivated lands is a widespread phenomenon in the Eastern Cape Province of South Africa, particularly in the communal lands. Most abandoned lands are associated with the replacement of indigenous perennial vegetation species by arid condition shrubs, impairment of soil biophysical properties and severe gully erosion. Despite the propensity of abandoned lands to severe erosion, they have rarely been addressed in land use modelling studies (Mulligan, 2004). In order to gain an understanding of land use and vegetation changes, and the development of gully erosion, sequential aerial photographs taken between 1938 and 1988, and infrared images for 2001 and 2005 were analysed. Soil surface strength as a surrogate for soil crusting was assessed under P. incana clusters and remnant grass patches using a hand-operated cone penetrometer. Relationships between the mapped phenomena and topographic variables were sought using a 20m Digital Elevation Model. Evidence from aerial photography, infrared imagery and field observations indicated that P. incana invasion parallels land use change and patterns. Abandoned lands, particularly on steep south facing slopes were noted as predisposed to invasion by P. incana. A predominance of gullying on abandoned lands was noted, as 80% of the total gullied area lies on abandoned lands. The development of gullies on abandoned lands within the gentle lower concave hillslope elements of the study area highlights how low the topographic threshold for gully development is on abandoned lands. A comparative assessment of soil surface conditions showed that crusting under P. incana interpatch bare areas is significantly greater than under grass. This implies significantly greater runoff generation under the former than the latter. The absence of appropriate management strategies and the high erodibility of the soils rendered abandoned lands vulnerable to erosion. Soil physical properties and disturbance in the form of land abandonment are envisaged to have interacted to cause a shift in water availability beyond the uptake threshold for grass species, hence the replacement by P. incana. The spatial correlation between gullying and abandoned lands within concave colluvial bottom lands demonstrated that the topographic threshold for gully erosion is very low where land use, topography and soil properties interact.

Kakembo, V.

2009-04-01

375

Differences in soil fungal communities between European beech (Fagus sylvatica L.) dominated forests are related to soil and understory vegetation.  

PubMed

Fungi are important members of soil microbial communities with a crucial role in biogeochemical processes. Although soil fungi are known to be highly diverse, little is known about factors influencing variations in their diversity and community structure among forests dominated by the same tree species but spread over different regions and under different managements. We analyzed the soil fungal diversity and community composition of managed and unmanaged European beech dominated forests located in three German regions, the Schwäbische Alb in Southwestern, the Hainich-Dün in Central and the Schorfheide Chorin in the Northeastern Germany, using internal transcribed spacer (ITS) rDNA pyrotag sequencing. Multiple sequence quality filtering followed by sequence data normalization revealed 1655 fungal operational taxonomic units. Further analysis based on 722 abundant fungal OTUs revealed the phylum Basidiomycota to be dominant (54%) and its community to comprise 71.4% of ectomycorrhizal taxa. Fungal community structure differed significantly (p?0.001) among the three regions and was characterized by non-random fungal OTUs co-occurrence. Soil parameters, herbaceous understory vegetation, and litter cover affected fungal community structure. However, within each study region we found no difference in fungal community structure between management types. Our results also showed region specific significant correlation patterns between the dominant ectomycorrhizal fungal genera. This suggests that soil fungal communities are region-specific but nevertheless composed of functionally diverse and complementary taxa. PMID:23094057

Wubet, Tesfaye; Christ, Sabina; Schöning, Ingo; Boch, Steffen; Gawlich, Melanie; Schnabel, Beatrix; Fischer, Markus; Buscot, François

2012-10-18

376

Differences in Soil Fungal Communities between European Beech (Fagus sylvatica L.) Dominated Forests Are Related to Soil and Understory Vegetation  

PubMed Central

Fungi are important members of soil microbial communities with a crucial role in biogeochemical processes. Although soil fungi are known to be highly diverse, little is known about factors influencing variations in their diversity and community structure among forests dominated by the same tree species but spread over different regions and under different managements. We analyzed the soil fungal diversity and community composition of managed and unmanaged European beech dominated forests located in three German regions, the Schwäbische Alb in Southwestern, the Hainich-Dün in Central and the Schorfheide Chorin in the Northeastern Germany, using internal transcribed spacer (ITS) rDNA pyrotag sequencing. Multiple sequence quality filtering followed by sequence data normalization revealed 1655 fungal operational taxonomic units. Further analysis based on 722 abundant fungal OTUs revealed the phylum Basidiomycota to be dominant (54%) and its community to comprise 71.4% of ectomycorrhizal taxa. Fungal community structure differed significantly (p?0.001) among the three regions and was characterized by non-random fungal OTUs co-occurrence. Soil parameters, herbaceous understory vegetation, and litter cover affected fungal community structure. However, within each study region we found no difference in fungal community structure between management types. Our results also showed region specific significant correlation patterns between the dominant ectomycorrhizal fungal genera. This suggests that soil fungal communities are region-specific but nevertheless composed of functionally diverse and complementary taxa.

Schoning, Ingo; Boch, Steffen; Gawlich, Melanie; Schnabel, Beatrix; Fischer, Markus; Buscot, Francois

2012-01-01

377

Geothermal environmental assessment baseline study: vegetation and soils of the Roosevelt Hot Springs Geothermal Resource Area  

SciTech Connect

Identification and elemental concentrations of indigenous soil and plant systems found on the Roosevelt Hot Spring KGRA are described. Twenty-three different soils and five separate plant communities are geographically mapped and identified. One hundred forty-seven plant species were identified. Forbs, shrubs, and grasses are represented by 58, 53, and 36 species respectively. Three sites, each measuring 25 hectares, were selected for long-term vegetative assessment. At these locations a permanent enclosure measuring 24.4 meters x 24.4 meters was constructed to assess long-term effects of livestock grazing. Biomass, plant species, percentage composition, ground cover and livestock carrying capacities were determined at each site. Surface soils and Artemisia tridentata leaf tissue were collected for elemental analysis.

Brown, K.W.; Wiersma, G.B.

1981-07-01

378

GeoInformation studies of soil and vegetation patterns along Climatic Gradients: A Review  

NASA Astrophysics Data System (ADS)

Global evidence regarding magnitudes of desertification processes and recognition in their societal, ecological and climatological consequences had lead the international community to establish the United Nations Convention to Combat Desertification (UNCCD). Within the framework of this convention it is perceived that Desertification is a complex poorly understood phenomena which is " first and foremost, the result of resource management failures". Scientific research within this context have three primary roles: monitoring the situation, developing the understanding of relationships between factors promoting desertification and finally providing the international community with efficient recommendations regarding actions which may slow down these processes. Study of desertification processes in regions of sharp climatic gradients is of special importance within this framework since they represent areas where the processes are most intensive and where most deserts actually expand. The detection of threshold zones coupling sever land degradation with loss of resilience in their eco-geomophic systems is fundamental for the efficient combating of global desertification. Application of geoinformation tools and techniques is instrumental for this purpose: mapping biological, chemical and physical surface properties using remote sensing techniques, mapping historical patch-pattern changes using air-photographs, analysis of spatio-temporal variations in pattern properties and analysis of informational relationships between these surface properties and patterns with climatoloical, topographic, lithological and human factors. Numerous Remote Sensing studies had been undertaken during the last four decades in monitoring desertification through the provision of maps describing spatial distributions of biophysical surface parameters at resolutions between few meters to few kilometers and temporal resolutions between hours and weeks. These studies utilized radar backscattering , spectral reflectance at the visible, NIR and SWIR ranges and emissions in the thermal spectrum. However, despite the magnitude of these projects very few of the methods were proved to be operational yet. The main shortcomings of exiting methods are: - They are highly dependent on accurate calibration which for large region is impractical. - Most of the methods are semi-empirical: case dependent rather than representing robust physical indicators. - There is no one imagery source which is good for all mapping purposes, most of the methods use single imagery source and there is relatively little synergy (fusion) between imagery sources. - Data continuity for long time periods exits mainly for low resolution sources which are limited in supporting modeling of processes. - Difficulties in scaling-up results and methods from the local to the broad-regional scales Within the scope of interest here the most important shortcoming concern the fact that relatively little work treated explicitly regions of high climatic gradient partly due to their high spatio-temporal heterogeneity. Three areas of recent advancements in studying explicitly transition zones between humid and arid regions : - Mapping bio-physical properties of vegetation forms (herbaceous, dwarf-shrubs and shrubs): cover proportions, biomass, primary productivity using synergy between optical (phonologies) and SAR imagery. - Mapping chemical and physical soil properties and estimating their erodibility using hyper and multi spectral methods, and SAR backscattering. - Mapping soil and vegetation patch patterns and their changes within the last decades using historical air-photographs. These advancement s lead to the detection of threshold zones between regions along these gradients according to following indicators: - Life-forms compositions, biomass and primary productivity. Analysis of relationships between biomass and rainfall allow differentiation between cases were vegetation compositions and properties which follow 'expected' successional sequences and those which represent harsh land degr

Shoshany, M.

2009-04-01

379

Uptake of explosives from contaminated soil by existing vegetation at the Joliet Army Ammunition Plant  

SciTech Connect

This study examines the uptake of explosives by existing vegetation growing in TNT-contaminated soils on Group 61 at the Joliet Army Ammunition Plant (JAAP). The soils in this group were contaminated more than 40 years ago. In this study, existing plant materials and soil from the root zone were sampled from 15 locations and analyzed to determine TNT uptake by plants under natural field conditions. Plant materials were separated by species if more than one species was present at a sampling location. Standard methods were used to determine concentrations of explosives, their derivatives, and metabolites in the soil samples. Plant materials were also analyzed. No. explosives were detected in the aboveground portion of any plant sample. However, the results indicate that TNT, 2-amino DNT, and/or 4-amino DNT were found in some root samples of false boneset (Kuhnia eupatorioides), teasel (Dipsacus sylvestris), and bromegrass (Bromus inermis). It is possible that slight soil contamination remained on the roots, especially in the case of the very fine roots for species like bromegrass, where washing was difficult. The presence of 2-amino DNT and 4-amino DNT, which could be plant metabolites of TNT, increases the likelihood that explosives were taken up by plant roots, as opposed to their presence resulting from external soil contamination.

Schneider, J.F.; Tomczyk, N.A.; Zellmer, S.D. [Argonne National Lab., IL (United States); Banwart, W.L. [Argonne National Lab., IL (United States)]|[Univ., of Illinois, Urbana, IL (United States). Dept., of Agronomy

1994-01-01

380

Use of arsenic contaminated irrigation water for lettuce cropping: effects on soil, groundwater, and vegetal.  

PubMed

The present study investigated the effects of using arsenic (As) contaminated irrigation water in Lactuca sativa L. cropping. Two different arsenic concentrations, i.e., 25 and 85 ?g L(-1) and two different soils</