Sample records for soil vegetation model

  1. A nonlinear coupled soil moisture-vegetation model

    NASA Astrophysics Data System (ADS)

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

    2005-06-01

    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.

  2. Modeling radium and radon transport through soil and vegetation

    USGS Publications Warehouse

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

    2003-01-01

    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.

  3. Modeling radium and radon transport through soil and vegetation.

    PubMed

    Kozak, Joseph Alexander; Reeves, Howard William; Lewis, Barbara Ann

    2003-11-01

    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. PMID:14568398

  4. Soil detachment by overland flow under different vegetation restoration models in the loess plateau of China

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Land use change has significant effects on soil properties and vegetation cover and thus probably affects soil detachment by overland flow. Few studies were conducted to evaluate the effect of restoration models on the soil detachment process in the Loess Plateau in the past decade during which a Gr...

  5. Downscaling scheme to drive soil-vegetation-atmosphere transfer models

    NASA Astrophysics Data System (ADS)

    Schomburg, Annika; Venema, Victor; Lindau, Ralf; Ament, Felix; Simmer, Clemens

    2010-05-01

    The earth's surface is characterized by heterogeneity at a broad range of scales. Weather forecast models and climate models are not able to resolve this heterogeneity at the smaller scales. Many processes in the soil or at the surface, however, are highly nonlinear. This holds, for example, for evaporation processes, where stomata or aerodynamic resistances are nonlinear functions of the local micro-climate. Other examples are threshold dependent processes, e.g., the generation of runoff or the melting of snow. It has been shown that using averaged parameters in the computation of these processes leads to errors and especially biases, due to the involved nonlinearities. Thus it is necessary to account for the sub-grid scale surface heterogeneities in atmospheric modeling. One approach to take the variability of the earth's surface into account is the mosaic approach. Here the soil-vegetation-atmosphere transfer (SVAT) model is run on an explicit higher resolution than the atmospheric part of a coupled model, which is feasible due to generally lower computational costs of a SVAT model compared to the atmospheric part. The question arises how to deal with the scale differences at the interface between the two resolutions. Usually the assumption of a homogeneous forcing for all sub-pixels is made. However, over a heterogeneous surface, usually the boundary layer is also heterogeneous. Thus, by assuming a constant atmospheric forcing again biases in the turbulent heat fluxes may occur due to neglected atmospheric forcing variability. Therefore we have developed and tested a downscaling scheme to disaggregate the atmospheric variables of the lower atmosphere that are used as input to force a SVAT model. Our downscaling scheme consists of three steps: 1) a bi-quadratic spline interpolation of the coarse-resolution field; 2) a "deterministic" part, where relationships between surface and near-surface variables are exploited; and 3) a noise-generation step, in which the still missing, not explained, variance is added as noise. The scheme has been developed and tested based on high-resolution (400 m) model output of the weather forecast (and regional climate) COSMO model. Downscaling steps 1 and 2 reduce the error made by the homogeneous assumption considerably, whereas the third step leads to close agreement of the sub-grid scale variance with the reference. This is, however, achieved at the cost of higher root mean square errors. Thus, before applying the downscaling system to atmospheric data a decision should be made whether the lowest possible errors (apply only downscaling step 1 and 2) or a most realistic sub-grid scale variability (apply also step 3) is desired. This downscaling scheme is currently being implemented into the COSMO model, where it will be used in combination with the mosaic approach. However, this downscaling scheme can also be applied to drive stand-alone SVAT models or hydrological models, which usually also need high-resolution atmospheric forcing data.

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

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

    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.

  7. Measuring and modeling water-related soil-vegetation feedbacks in a fallow plot

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    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 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.

  8. Modeling the effects of vegetation on methane oxidation and emissions through soil landfill final covers across different climates.

    PubMed

    Abichou, Tarek; Kormi, Tarek; Yuan, Lei; Johnson, Terry; Francisco, Escobar

    2015-02-01

    Plant roots are reported to enhance the aeration of soil by creating secondary macropores which improve the diffusion of oxygen into soil as well as the supply of methane to bacteria. Therefore, methane oxidation can be improved considerably by the soil structuring processes of vegetation, along with the increase of organic biomass in the soil associated with plant roots. This study consisted of using a numerical model that combines flow of water and heat with gas transport and oxidation in soils, to simulate methane emission and oxidation through simulated vegetated and non-vegetated landfill covers under different climatic conditions. Different simulations were performed using different methane loading flux (5-200 g m(-2) d(-1)) as the bottom boundary. The lowest modeled surface emissions were always obtained with vegetated soil covers for all simulated climates. The largest differences in simulated surface emissions between the vegetated and non-vegetated scenarios occur during the growing season. Higher average yearly percent oxidation was obtained in simulations with vegetated soil covers as compared to non-vegetated scenario. The modeled effects of vegetation on methane surface emissions and percent oxidation were attributed to two separate mechanisms: (1) increase in methane oxidation associated with the change of the physical properties of the upper vegetative layer and (2) increase in organic matter associated with vegetated soil layers. Finally, correlations between percent oxidation and methane loading into simulated vegetated and non-vegetated covers were proposed to allow decision makers to compare vegetated versus non-vegetated soil landfill covers. These results were obtained using a modeling study with several simplifying assumptions that do not capture the complexities of vegetated soils under field conditions. PMID:25475118

  9. Measuring and Modelling water related soil - vegetation feedbacks in a fallow plot

    NASA Astrophysics Data System (ADS)

    Ursino, Nadia; Cassiani, Giorgio; Deiana, Rita; Vignoli, Giulio; Boaga, Jacopo

    2013-04-01

    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 objective of this study was to test the potential of integrated non invasive geophysics 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 an infiltration experiment. One plot was left unseeded and the other was cultivated. The comparative analysis of the experimental data evidenced 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 site.

  10. A conceptual model of coastal dune ecology synthesizing spatial gradients of vegetation, soil, and geomorphology

    Microsoft Academic Search

    Daehyun Kim; Keun Bae Yu

    2009-01-01

    Patterns of coastal dune vegetation are closely related with soil conditions controlled by geomorphic forms and processes.\\u000a This study developed a conceptual model integrating these relationships in a spatially explicit manner. A rectangle of 180 × 280 m\\u000a containing 126 grids of 20 × 20 m was established in the Sindu coastal dunefield in west Korean Peninsula. Sampling from each\\u000a grid determined 11 soil properties and

  11. A dynamic soil water threshold for vegetation water stress derived from stomatal conductance models

    Microsoft Academic Search

    Ryan E. Emanuel; Paolo D'Odorico; Howard E. Epstein

    2007-01-01

    In many terrestrial ecosystems, vegetation experiences limitation by different resources at different times. These resources include, among others, light, nutrients, and water. Frequently, however, leaf-level modeling frameworks that unite these limitations rely on empirical functions to scale stomatal conductance as a function of water stress. These functions use prescribed values of soil water content to mark the transition between water-stressed

  12. Spatial variability models of soil respiration from some vegetation types in Maritime Antarctica

    Microsoft Academic Search

    Newton La Scala Jr.; Eduardo S. Mendonça; Alan Rodrigo Panosso; Felipe N. Dimas; Carlos Eduardo G. Schaefer

    2010-01-01

    Soil respiration is an important part of the terrestrial carbon cycling and is influenced by several aspects, such as type and distribution of vegetation. In this work we evaluated the spatial variability of the soil respiration (or soil CO2 emission) in three sites located in Maritime Antarctica at Admiralty Bay, King George Island under contrasting vegetation, representative of this region:

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

    NASA Astrophysics Data System (ADS)

    Liu, Shuguang; Bliss, Norman; Sundquist, Eric; Huntington, Thomas G.

    2003-06-01

    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 ecosystems 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.

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

    USGS Publications Warehouse

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

    2003-01-01

    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.

  15. Development and validation of a dynamical atmosphere-vegetation-soil HTO transport and OBT formation model.

    PubMed

    Ota, Masakazu; Nagai, Haruyasu

    2011-09-01

    A numerical model simulating transport of tritiated water (HTO) in atmosphere-soil-vegetation system, and, accumulation of organically bound tritium (OBT) in vegetative leaves was developed. Characteristic of the model is, for calculating tritium transport, it incorporates a dynamical atmosphere-soil-vegetation model (SOLVEG-II) that calculates transport of heat and water, and, exchange of CO(2). The processes included for calculating tissue free water tritium (TFWT) in leaves are HTO exchange between canopy air and leaf cellular water, root uptake of aqueous HTO in soil, photosynthetic assimilation of TFWT into OBT, and, TFWT formation from OBT through respiration. Tritium fluxes at the last two processes are input to a carbohydrate compartment model in leaves that calculates OBT translocation from leaves and allocation in them, by using photosynthesis and respiration rate in leaves. The developed model was then validated through a simulation of an existing experiment of acute exposure of grape plants to atmospheric HTO. Calculated TFWT concentration in leaves increased soon after the start of HTO exposure, reaching to equilibrium with the atmospheric HTO within a few hours, and then rapidly decreased after the end of the exposure. Calculated non-exchangeable OBT amount in leaves linearly increased during the exposure, and after the exposure, rapidly decreased in daytime, and, moderately nighttime. These variations in the calculated TFWT concentrations and OBT amounts, each mainly controlled by HTO exchange between canopy air and leaf cellular water and by carbohydrates translocation from leaves, fairly agreed with the observations within average errors of a factor of two. PMID:21665337

  16. Assessment of Uncertainty of Forest Road Hydrology Modeling with the Distributed Hydrology Soil Vegetation Model (DHSVM)

    NASA Astrophysics Data System (ADS)

    Surfleet, C. G.; Skaugset, A. E.; McDonnell, J.

    2007-12-01

    The effects of forest roads on catchment hydrology and sediment production continue to be the focus of concern for impacts to aquatic habitat. However, these processes are complex and difficult to measure at catchment scales. Consequently, the effects of forest roads on watershed hydrology are often studied using distributed hydrologic models. We examined a popular distributed hydrology model used in the Western USA, the Distributive Hydrology Soil Vegetation Model (DHSVM), to predict changes in peak flows, storm run-off volume, and interception of sub-surface flow from forest roads. We apply DHSVM to a 630 hectare watershed in the headwaters of Oak Creek in the McDonald/Dunn Research Forest, managed by the College of Forestry, Oregon State University. The Generalized Likelihood Uncertainty Estimation (GLUE) approach was used to determine the uncertainty of model output for 10,000 model structures. Estimates of road ditchflow and streamflow from the GLUE assessment of DHSVM were compared to observed road ditchflow and streamflow for 2003-2006. Generally DHSVM simulations provided a reasonable fit to the time series for Oak Creek streamflow. The fit of the time series data diminished with spatial scale and for road ditchflow locations. From the GLUE assessment the percentage of DHSVM model structures that exceeded a Nash/Sutcliffe Efficiency of 0.5 were 44% for Oak Creek streamflow but reduced to a range of 0-9% for road locations. The conceptual model for road interception used within DHSVM did not accurately predict road ditchflow throughout the catchment. Given the many uncertainties observed from DHSVM road ditchflow results we question whether cumulative effects analysis of road influences on peak flows and storm volumes with DHSVM is appropriate for catchments with highly variable hillslope responses, such as Oak Creek.

  17. Smart plants, smart models? On adaptive responses in vegetation-soil systems

    NASA Astrophysics Data System (ADS)

    van der Ploeg, Martine; Teuling, Ryan; van Dam, Nicole; de Rooij, Gerrit

    2015-04-01

    Hydrological models that will be able to cope with future precipitation and evapotranspiration regimes need a solid base describing the essence of the processes involved [1]. The essence of emerging patterns at large scales often originates from micro-behaviour in the soil-vegetation-atmosphere system. A complicating factor in capturing this behaviour is the constant interaction between vegetation and geology in which water plays a key role. The resilience of the coupled vegetation-soil system critically depends on its sensitivity to environmental changes. To assess root water uptake by plants in a changing soil environment, a direct indication of the amount of energy required by plants to take up water can be obtained by measuring the soil water potential in the vicinity of roots with polymer tensiometers [2]. In a lysimeter experiment with various levels of imposed water stress the polymer tensiometer data suggest maize roots regulate their root water uptake on the derivative of the soil water retention curve, rather than the amount of moisture alone. As a result of environmental changes vegetation may wither and die, or these changes may instead trigger gene adaptation. Constant exposure to environmental stresses, biotic or abiotic, influences plant physiology, gene adaptations, and flexibility in gene adaptation [3-7]. To investigate a possible relation between plant genotype, the plant stress hormone abscisic acid (ABA) and the soil water potential, a proof of principle experiment was set up with Solanum Dulcamare plants. The results showed a significant difference in ABA response between genotypes from a dry and a wet environment, and this response was also reflected in the root water uptake. Adaptive responses may have consequences for the way species are currently being treated in models (single plant to global scale). In particular, model parameters that control root water uptake and plant transpiration are generally assumed to be a property of the plant functional type. Assigning plant functional types does not allow for local plant adaptation to be reflected in the model parameters, nor does it allow for correlations that might exist between root parameters and soil type. [1] Seibert, J. 2000. Multi-criteria calibration of a conceptual runoff model using a genetic algorithm. Hydrology and Earth System Sciences 4(2): 215-224. [2] Van der Ploeg, M.J., H.P.A. Gooren, G. Bakker, C.W. Hoogendam, C. Huiskes, L.K. Koopal, H. Kruidhof and G.H. de Rooij. 2010. Polymer tensiometers with ceramic cones: performance in drying soils and comparison with water-filled tensiometers and time domain reflectometry. Hydrol. Earth Syst. Sci. 14: 1787-1799, doi: 10.5194/hess-14-1787-2010. [3] McClintock B. The significance of responses of the genome to challenge. Science 1984; 226: 792-801 [4] Ries G, Heller W, Puchta H, Sandermann H, Seldlitz HK, Hohn B. Elevated UV-B radiation reduces genome stability in plants. Nature 2000; 406: 98-101 [5] Lucht JM, Mauch-Mani B, Steiner H-Y, Metraux J-P, Ryals, J, Hohn B. Pathogen stress increases somatic recombination frequency in Arabidopsis. Nature Genet. 2002; 30: 311-314 [6] Kovalchuk I, Kovalchuk O, Kalck V., Boyko V, Filkowski J, Heinlein M, Hohn B. Pathogen-induced systemic plant signal triggers DNA rearrangements. Nature 2003; 423: 760-762 [7] Cullis C A. Mechanisms and control of rapid genomic changes in flax. Ann. Bot. (Lond.) 2005; 95: 201-206

  18. Distributed Hydrology Soil Vegetation Model (DHSVM) and Sediment Discharge Validation in a small, Pacific Northwestern Watershed

    NASA Astrophysics Data System (ADS)

    Huggett, B. W.; Stubblefield, A. P.; Dhakal, A. S.; Sullivan, K.

    2009-12-01

    The Distributed Soil Vegetation Model (DHSVM) and its sediment production prediction capabilities are evaluated in a small, gaged, timber-production watershed in northwestern California. McReady Creek drains a 5 km2 basin dominated by coastal redwood (Sequoia sempervirens). Forest soils are fine grained and poorly consolidated marine sediments approximately 40 kya. Stream and sediment discharge data collected by Humboldt State University and Humboldt Redwoods Company (HRC) from 2003 to present were used to calibrate and validate DHSVM. Model parameters like forest stand (over- and understory height, fractional coverage, monthly LAI, etc) and soil characteristics (porosity, bulk density, field capacity, etc) were measured via in-field investigations or gathered by HRC through timber cruising activities. All data was gridded to 10 meters for the analysis. Forest stand data was manipulated throughout the model run to reflect the operational nature of the watershed. Modeled stream discharge will be evaluated against observed discharge on an event by event basis, as well as against weekly and monthly totals. Modeled sediment discharge will be evaluated on a similar basis, including total annual sediment discharge. Sources of potential incoherence between modeled and observed data may be road density (6.7 km / km2) and road/stream connectivity or the presence of legacy forest practices that still produce sediment within the basin. Further work will involve field investigations that will clarify road/stream connectivity and legacy sediment production zones.

  19. Effects of ionic strength, particle size, flow rate, and vegetation type on colloid transport through a dense vegetation saturated soil system: Experiments and modeling

    NASA Astrophysics Data System (ADS)

    Yu, Congrong; Muñoz-Carpena, Rafael; Gao, Bin; Perez-Ovilla, Oscar

    2013-08-01

    Colloids are widely distributed in agricultural runoff, especially from croplands with manure applications. Dense vegetation has been suggested to be effective to reduce surface runoff contaminants, including colloidal particles. In this work, small scale laboratory experiments were used to determine the influence of physical and chemical factors (i.e. solution ionic strength, particle size, surface flow rate, and vegetation type) on the surface transport and removal of colloids in a dense vegetation system without drainage. Conservative tracer studies of bromide were conducted as a control to quantify the deposition of colloids onto grass surfaces and the mass exchange of colloids between the overland flow and soil underneath under various experimental conditions. The deposition of colloids enhanced with increases in solution ionic strength and particle size, and with decreases in flow rate. We also found vegetation type played an important role on colloid transport with more deposition onto Ryegrass than onto Bahia grass under the same experimental conditions. A mathematical model combining overland flow, convection-dispersion equations and exchange layer theory was developed to simulate the transport of colloids in overland flow through the dense vegetation. Simulations of the model fitted the experimental data well and helped to understand the effect of ionic strength, particle size, flow rate, and vegetation type on colloid transport and removal in dense vegetation. Although additional investigations are still needed, findings from this study can inform the installation and maintenance of dense vegetation systems, such as vegetative filter strips, to reduce the loading of colloids in surface runoff.

  20. Mapping crop evapotranspiration by integrating vegetation indices into a soil water balance model

    NASA Astrophysics Data System (ADS)

    Consoli, Simona; Vanella, Daniela

    2015-04-01

    The approach combines the basal crop coefficient (Kcb) derived from vegetation indices (VIs) with the daily soil water balance, as proposed in the FAO-56 paper, to estimate daily crop evapotranspiration (ETc) rates of orange trees. The reliability of the approach to detect water stress was also assessed. VIs were simultaneously retrieved from WorldView-2 imagery and hyper-spectral data collected in the field for comparison. ETc estimated were analysed at the light of independent measurements of the same fluxes by an eddy covariance (EC) system located in the study area. The soil water depletion in the root zone of the crop simulated by the model was also validated by using an in situ soil water monitoring. Average overestimate of daily ETc of 6% was obtained from the proposed approach with respect to EC measurements, evidencing a quite satisfactory agreement between data. The model also detected several periods of light stress for the crop under study, corresponding to an increase of the root zone water deficit matching quite well the in situ soil water monitoring. The overall outcomes of this study showed that the FAO-56 approach with remote sensing-derived basal crop coefficient can have the potential to be applied for estimating crop water requirements and enhancing water management strategies in agricultural contexts.

  1. Evaluating dynamic global vegetation models using meta-data analyses on soil carbon changes following land use change

    NASA Astrophysics Data System (ADS)

    Nyawira, Sylvia; Don, Axel; Nabel, Julia; Brovkin, Victor; Pongratz, Julia

    2015-04-01

    A major driver of changes in soil carbon in recent centuries has been land-use change. While evidence of land-use-related soil carbon changes exists based on local-scale observations, global estimates of these changes rely on modeling and remain highly uncertain. To understand the applicability of models to making future projections of soil carbon changes due to land use change, it is important to evaluate models using observations on soil carbon. A range of meta-data analyses on soil carbon changes following land use change has been published recently, aggregating local observations to levels potentially applicable to dynamic global vegetation models (DGVMs). However, up to now, this data has not been compared to DGVM simulations. The aim of this work is to develop an approach for evaluating DGVMs using these meta-analyses and apply the approach to evaluate the newly implemented soil carbon scheme-YASSO in the DGVM-JSBACH. YASSO is driven by vegetation productivity from JSBACH. However, the productivity by JSBACH is known to have biases in some regions as compared to what is observed in reality. To account for these biases, we confine the litter inputs to soils close to observations and constrain the decomposition by forcing YASSO with observed vegetation productivity and climate. Later we assess the bias introduced by JSBACH vegetation productivity on the soil carbon response in YASSO. We perform idealized simulations from one land-use to another to mimic the observational set-ups that the meta-data analyses comprise. To compare the simulated soil carbon response in the model with the meta-data, we select homogeneous physical regions based on the factors identified in literature as to influence the spatial and temporal variability of changes in soil carbon following land use change. Both the simulated equilibrium and the transient response of soil carbon to land use change simulated by YASSO for these regions is then compared with the meta-data analyses.

  2. The influence of soil type, vegetation cover and soil moisture on spin up behaviour of a land surface model in a monsoonal region

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Anwesha; Mandal, Manabottam

    2015-04-01

    Model spin-up is the process through which the model is adequately equilibrated to ensure balance between the mass fields and velocity fields. In this study, an offline one dimensional Noah land surface model is integrated recursively for three years to assess its spin-up behavior at different sites over the Indian Monsoon domain. Several numerical experiments are performed to investigate the impact of soil category, vegetation cover, initial soil moisture and subsequent dry or wet condition on model spin-up. These include simulations with the dominant soil and vegetation covers of this region, different initial soil moisture content (observed soil moisture; dry soil; moderately wet soil; saturated soil), simulations initialized at different rain conditions (no rain; infrequent rain; continuous rain) and different seasons (Winter, Spring, Summer/Pre-Monsoon, Monsoon and Autumn). It is seen that the spin-up behavior of the model depends on the soil type and vegetation cover with soil characteristics having the larger influence. Over India, the model has the longest spin-up in the case of simulations with loamy soil covered with mixed-shrub. It is noted that the model has a significantly longer spin-up when initialized with very low initial soil moisture content than with higher soil moisture content. It is also seen that in general, simulations initialized just before a continuous rainfall event have the least spin-up time. This observation is reinforced by the results from the simulations initialized in different seasons. It is seen that for monsoonal region, the model spin-up time is least for simulations initialized just before the Monsoon. Model initialized during the Monsoon rain episodes has a longer spin-up than that initialized in any other season. Furthermore, it is seen that the model has a shorter spin-up if it reaches the equilibrium state predominantly via drying process and could be as low as two months under quasi-equilibrium condition depending on the time of initialization.

  3. Levels of tritium in soils and vegetation near Canadian nuclear facilities releasing tritium to the atmosphere: implications for environmental models.

    PubMed

    Thompson, P A; Kwamena, N-O A; Ilin, M; Wilk, M; Clark, I D

    2015-02-01

    Concentrations of organically bound tritium (OBT) and tritiated water (HTO) were measured over two growing seasons in vegetation and soil samples obtained in the vicinity of four nuclear facilities and two background locations in Canada. At the background locations, with few exceptions, OBT concentrations were higher than HTO concentrations: OBT/HTO ratios in vegetation varied between 0.3 and 20 and values in soil varied between 2.7 and 15. In the vicinity of the four nuclear facilities OBT/HTO ratios in vegetation and soils deviated from the expected mean value of 0.7, which is used as a default value in environmental transfer models. Ratios of the OBT activity concentration in plants ([OBT]plant) to the OBT activity concentration in soils ([OBT]soil) appear to be a good indicator of the long-term behaviour of tritium in soil and vegetation. In general, OBT activity concentrations in soils were nearly equal to OBT activity concentrations in plants in the vicinity of the two nuclear power plants. [OBT]plant/[OBT]soil ratios considerably below unity observed at one nuclear processing facility represents historically higher levels of tritium in the environment. The results of our study reflect the dynamic nature of HTO retention and OBT formation in vegetation and soil during the growing season. Our data support the mounting evidence suggesting that some parameters used in environmental transfer models approved for regulatory assessments should be revisited to better account for the behavior of HTO and OBT in the environment and to ensure that modelled estimates (e.g., plant OBT) are appropriately conservative. PMID:25461522

  4. Modelling vegetation landslides

    NASA Astrophysics Data System (ADS)

    Vorpahl, Peter; Dislich, Claudia; Elsenbeer, Helmut; Märker, Michael; Schröder, Boris

    2010-05-01

    Shallow translational landslides are believed to represent a major ecosystem disturbance in the Andean rain forests of South Ecuador. Aiming at a better understanding of gap dynamics in this mega-diverse ecosystem, we investigated several landslides in an area of undisturbed tropical montane rain forest and found that in some cases almost no inorganic material was involved. Current physically-based landslide models cannot reproduce this type of process, since they focus on soil physical properties. Even though vegetation is incorporated in these models by its weight and by the contribution of roots to soil cohesion and hence to shear resistance, we think that the role of vegetation has to be viewed differently within this ecosystem: Roots do mainly grow in a thick organic layer above the mineral soil and do not penetrate sufficiently deep into the mineral soil to contribute to slope stability according to common models. To accommodate such circumstances, we formulated an extension to the widely used infinite slope model for assessing slope stability, and applied it to our research site. Biomass, root layer and soil properties before sliding events were reconstructed on and close to landslides that occurred within the preceding years. By introduction of an additional factor of safety for the organic layer, we are able to mathematically describe classical shallow translational landslides as well as vegetation slides. A high spatial and temporal variability of vegetation, root layer and soil physical properties within the research area complicate model applications. Thus we assumed spatial gradients for ranges of model parameters and stochastic parameter variations within these ranges according to our field measurements and published data. Finally we outline the model validation by comparison to historical landslide inventories. Possible applications of the model are located within undisturbed tropical montane rain forests and contribute to the fields of automated landslide classification as well as spatiotemporal modelling of landslides and forest gap dynamics.

  5. Radar backscatter sensitivity of soil moisture in vegetation covered areas

    Microsoft Academic Search

    Faisal Karim; Susan Steele-Dunne; Nick van de Giesen

    2010-01-01

    Radar backscatter is sensitive to the water content of bare soil surface. Vegetation cover masks the soil surface, reducing the sensitivity of the radar backscatter to soil moisture. The water-cloud model is used to account for vegetation effects on the copolarized backscatter coefficient in C and L band. In this sensitivity study, two different models for opacity are compared to

  6. Soil Moisture and Vegetation Controls on Surface Energy Balance Using the Maximum Entropy Production Model of Evapotranspiration

    NASA Astrophysics Data System (ADS)

    Wang, J.; Parolari, A.; Huang, S. Y.

    2014-12-01

    The objective of this study is to formulate and test plant water stress parameterizations for the recently proposed maximum entropy production (MEP) model of evapotranspiration (ET) over vegetated surfaces. . The MEP model of ET is a parsimonious alternative to existing land surface parameterizations of surface energy fluxes from net radiation, temperature, humidity, and a small number of parameters. The MEP model was previously tested for vegetated surfaces under well-watered and dry, dormant conditions, when the surface energy balance is relatively insensitive to plant physiological activity. Under water stressed conditions, however, the plant water stress response strongly affects the surface energy balance. This effect occurs through plant physiological adjustments that reduce ET to maintain leaf turgor pressure as soil moisture is depleted during drought. To improve MEP model of ET predictions under water stress conditions, the model was modified to incorporate this plant-mediated feedback between soil moisture and ET. We compare MEP model predictions to observations under a range of field conditions, including bare soil, grassland, and forest. The results indicate a water stress function that combines the soil water potential in the surface soil layer with the atmospheric humidity successfully reproduces observed ET decreases during drought. In addition to its utility as a modeling tool, the calibrated water stress functions also provide a means to infer ecosystem influence on the land surface state. Challenges associated with sampling model input data (i.e., net radiation, surface temperature, and surface humidity) are also discussed.

  7. Floodplain restoration leads to wetter and more diverse soil water regimes and vegetation types: Insight from an integrated hydroecological model

    NASA Astrophysics Data System (ADS)

    Booth, E. G.; Loheide, S. P.

    2011-12-01

    Soil moisture availability in the root zone is one of the most important factors affecting plant species composition by creating stress on vegetation both when it is lacking (water stress) and when it is excessive (oxygen stress). Plant species have individual tolerance ranges along a gradient of available soil moisture that can be described as a hydrological niche. Combining a hydrological model and a habitat niche model can provide spatially-extensive predictions of vegetation composition, which would be useful for land management decision-making under changing environmental conditions. Floodplain ecosystem restoration provides an example of the utility of such a predictive tool as a site is hydrologically altered to create a wetter environment. We developed an integrated hydroecological model that links a quasi-3D, variably-saturated, groundwater flow model that simulates soil moisture with several plant habitat niche models. The focus of this research is a floodplain in southwestern Wisconsin where post-settlement alluvium was removed with the expectation of increasing regionally-threatened wetland plant species. Hydrological niche models were created based on simultaneous observations of vegetation composition and surface effective saturation. These models were then used to predict probability of presence for two dominant plant species (Carex vulpinoidea and Elymus canadensis) and composite wetland indicator score based on simulated surface effective saturation across the study site. The model predicts the site to be more wetland-species dominant overall following restoration. However, the soil moisture regime and vegetation types are slightly drier following restoration in zones where a silt-clay confining layer is present that inhibits vertical groundwater flow from a basal gravel aquifer to the near-surface soil zone. This differential response to restoration leads to a mosaic of soil water regimes across the site, which is reflected in a wider distribution of vegetation types. Therefore, the management goal of increasing wetland plant species occurrence is shown to co-occur with an increase in the site-scale diversity of plant community types. This result reveals the unique ability of the presented modeling framework to predict vegetation composition and aid land managers that are faced with difficult management decisions in a complex and uncertain future.

  8. Thermal remote sensing of surface soil water content with partial vegetation cover for incorporation into climate models

    NASA Technical Reports Server (NTRS)

    Gillies, Robert R.; Carlson, Toby N.

    1995-01-01

    This study outlines a method for the estimation of regional patterns of surface moisture availability (M(sub 0)) 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 (AVHRR)) surface radiant temperature to a vegetation index (computed from satellite visible and near-infrared data) while coupling this association to an inverse modeling scheme. More than merely furnishing surface soil moisture values, the method constitues a new conceptual and practical approach for combining thermal infrared and vegetation index measurements for incorporating the derived values of M(sub 0) into hydrologic and atmospheric prediction models. Application of the technique is demonstrated for a region in and around the city of Newcastle upon Tyne situated in the northeast of England. A regional estimate of M(sub 0) is derived and is probabbly good for fractional vegetation cover up to 80% before errors in the estimated soil water content become unacceptably large. Moreover, a normalization scheme is suggested from which a nomogram, `universal triangle,' is constructed and is seen to fit the observed data well. The universal triangle also simplifies the inclusion of remotely derived M(sub 0) in hydrology and meteorological models and is perhaps a practicable step toward integrating derived data from satellite measurements in weather forecasting.

  9. Hydroecological model predictions indicate wetter and more diverse soil water regimes and vegetation types following floodplain restoration

    NASA Astrophysics Data System (ADS)

    Booth, Eric G.; Loheide, Steven P., II

    2012-06-01

    Transitions between aquatic and terrestrial ecosystems represent zones where soil moisture is a dominant factor influencing vegetation composition. Niche models based on hydrological and vegetation observations can be powerful tools for guiding management of these zones, especially when they are linked with physically based hydrological models. Floodplain restoration represents a unique opportunity to utilize such a predictive vegetation tool when a site's hydrology is altered to create a wetter environment. A variably saturated groundwater flow model was developed and used to simulate the soil moisture regime across a floodplain in Wisconsin where post-settlement alluvium was removed with the intent of increasing regionally threatened wetland plant species. Hydrological niche models based on simultaneous observations of vegetation composition and surface effective saturation were used to predict probability of presence for two plant species (Carex vulpinoidea (fox sedge) and Elymus canadensis(Canada wildrye)) and wetland indicator score (a composite indicator of relative frequency of species in five habitat categories) based on simulated surface effective saturation. The vegetation predictions following restoration are more wetland-species dominant overall. However, zones of the study site where a confining layer is present that decouples groundwater from the near-surface soil zone tend to be drier following restoration due to restricted upward groundwater flow and less soil water storage above the confining layer. As reflected by an increase in the interquartile range in the predicted wetland indicator score, this restoration technique may increase the site-scale spatial diversity of plant community types while simultaneously accomplishing the goal of increasing wetland plant species occurrence.

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

    NASA Astrophysics Data System (ADS)

    Kaplan, J. O.; Vanwalleghem, T.

    2012-04-01

    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.

  11. Modeled Impacts of Cover Crops and Vegetative Barriers on Corn Stover Availability and Soil Quality

    SciTech Connect

    Ian J. Bonner; David J. Muth Jr.; Joshua B. Koch; Douglas L. Karlen

    2014-06-01

    Environmentally benign, economically viable, and socially acceptable agronomic strategies are needed to launch a sustainable lignocellulosic biofuel industry. Our objective was to demonstrate a landscape planning process that can ensure adequate supplies of corn (Zea mays L.) stover feedstock while protecting and improving soil quality. The Landscape Environmental Assessment Framework (LEAF) was used to develop land use strategies that were then scaled up for five U.S. Corn Belt states (Nebraska, Iowa, Illinois, Indiana, and Minnesota) to illustrate the impact that could be achieved. Our results show an annual sustainable stover supply of 194 million Mg without exceeding soil erosion T values or depleting soil organic carbon [i.e., soil conditioning index (SCI)?>?0] when no-till, winter cover crop, and vegetative barriers were incorporated into the landscape. A second, more rigorous conservation target was set to enhance soil quality while sustainably harvesting stover. By requiring erosion to be <1/2 T and the SCI-organic matter (OM) subfactor to be >?0, the annual sustainable quantity of harvestable stover dropped to148 million Mg. Examining removal rates by state and soil resource showed that soil capability class and slope generally determined the effectiveness of the three conservation practices and the resulting sustainable harvest rate. This emphasizes that sustainable biomass harvest must be based on subfield management decisions to ensure soil resources are conserved or enhanced, while providing sufficient biomass feedstock to support the economic growth of bioenergy enterprises.

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

    Microsoft Academic Search

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

    1997-01-01

    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

  13. Investigation of Soil Moisture - Vegetation Interactions in Oklahoma

    E-print Network

    Ford, Trenton W.

    2013-03-06

    , but not well understood climate factor. This study examines soil moisture-vegetation health interactions using both in situ observations and land surface model simulations. For the observational study, soil moisture is taken from 20 in situ Oklahoma Mesonet...

  14. Representing the effects of alpine grassland vegetation cover on the simulation of soil thermal dynamics by ecosystem models applied to the Qinghai-Tibetan Plateau

    USGS Publications Warehouse

    Yi, S.; Li, N.; Xiang, B.; Wang, X.; Ye, B.; McGuire, A.D.

    2013-01-01

    Soil surface temperature is a critical boundary condition for the simulation of soil temperature by environmental models. It is influenced by atmospheric and soil conditions and by vegetation cover. In sophisticated land surface models, it is simulated iteratively by solving surface energy budget equations. In ecosystem, permafrost, and hydrology models, the consideration of soil surface temperature is generally simple. In this study, we developed a methodology for representing the effects of vegetation cover and atmospheric factors on the estimation of soil surface temperature for alpine grassland ecosystems on the Qinghai-Tibetan Plateau. Our approach integrated measurements from meteorological stations with simulations from a sophisticated land surface model to develop an equation set for estimating soil surface temperature. After implementing this equation set into an ecosystem model and evaluating the performance of the ecosystem model in simulating soil temperature at different depths in the soil profile, we applied the model to simulate interactions among vegetation cover, freeze-thaw cycles, and soil erosion to demonstrate potential applications made possible through the implementation of the methodology developed in this study. Results showed that (1) to properly estimate daily soil surface temperature, algorithms should use air temperature, downward solar radiation, and vegetation cover as independent variables; (2) the equation set developed in this study performed better than soil surface temperature algorithms used in other models; and (3) the ecosystem model performed well in simulating soil temperature throughout the soil profile using the equation set developed in this study. Our application of the model indicates that the representation in ecosystem models of the effects of vegetation cover on the simulation of soil thermal dynamics has the potential to substantially improve our understanding of the vulnerability of alpine grassland ecosystems to changes in climate and grazing regimes.

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

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

    A simple hydrologic feedback model has been developed to simulate daily responses of hydrologic processes including interception, runoff, evapotranspiration, infiltration, and recharge under various conditions of vegetation, land cover, and soil in a fully-distributed manner. The daily soil water balance is a key element to link surface and subsurface models as it calculates infiltration and groundwater recharge by considering a time delay routing through a vadose zone down to the groundwater table. MODFLOW is adopted to simulate groundwater flow and interaction with surface water components as well. The model also can easily be localized by simple modification of soil and crop properties. The actual application of the model for a watershed in the Geum River Basin in Korea showed reliable hydrologic feedbacks between the surface and subsurface hydrologic systems.

  16. Representing the effects of alpine grassland vegetation cover on the simulation of soil thermal dynamics by ecosystem models applied to the Qinghai-Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Yi, S.; Li, N.; Xiang, B.; Wang, X.; Ye, B.; McGuire, A. D.

    2013-07-01

    surface temperature is a critical boundary condition for the simulation of soil temperature by environmental models. It is influenced by atmospheric and soil conditions and by vegetation cover. In sophisticated land surface models, it is simulated iteratively by solving surface energy budget equations. In ecosystem, permafrost, and hydrology models, the consideration of soil surface temperature is generally simple. In this study, we developed a methodology for representing the effects of vegetation cover and atmospheric factors on the estimation of soil surface temperature for alpine grassland ecosystems on the Qinghai-Tibetan Plateau. Our approach integrated measurements from meteorological stations with simulations from a sophisticated land surface model to develop an equation set for estimating soil surface temperature. After implementing this equation set into an ecosystem model and evaluating the performance of the ecosystem model in simulating soil temperature at different depths in the soil profile, we applied the model to simulate interactions among vegetation cover, freeze-thaw cycles, and soil erosion to demonstrate potential applications made possible through the implementation of the methodology developed in this study. Results showed that (1) to properly estimate daily soil surface temperature, algorithms should use air temperature, downward solar radiation, and vegetation cover as independent variables; (2) the equation set developed in this study performed better than soil surface temperature algorithms used in other models; and (3) the ecosystem model performed well in simulating soil temperature throughout the soil profile using the equation set developed in this study. Our application of the model indicates that the representation in ecosystem models of the effects of vegetation cover on the simulation of soil thermal dynamics has the potential to substantially improve our understanding of the vulnerability of alpine grassland ecosystems to changes in climate and grazing regimes.

  17. Calibrating a soil-vegetation-atmosphere transfer model with remote sensing estimates of surface temperature and soil surface moisture in a semi arid environment

    NASA Astrophysics Data System (ADS)

    Ridler, Marc E.; Sandholt, Inge; Butts, Michael; Lerer, Sara; Mougin, Eric; Timouk, Franck; Kergoat, Laurent; Madsen, Henrik

    2012-05-01

    SummaryA series of numerical experiments has been designed to investigate how effective satellite estimates of radiometric surface temperatures and soil surface moisture are for calibrating a Soil-Vegetation-Atmosphere Transfer (SVAT) model. Multi-objective calibration based on error minimization of temperature and soil moisture model outputs is performed in a semi-arid environment. Model accuracy when calibrated using in situ versus satellite objectives is explored in detail. Observational meteorological datasets from the African Monsoon Multidisciplinary Analysis (AMMA) were used to force a column model during a growing season in Mali. Fourier Amplitude Sensitivity Test (FAST) revealed the most sensitive parameters to model outputs. Parameters found sensitive were subsequently optimized in a series of model calibrations to reveal trade-offs between model objectives. Our main findings are (1) the SVAT model performs well in the semi-arid environment, but underestimates peak growing season evapotranspiration and overestimates soil moisture, (2) most of the parameters important for flux estimates can be constrained using surface temperature and soil surface moisture with the three exceptions: root depth, the extinction coefficient and unstressed stomatal resistance, (3) flux simulations are improved when the model is calibrated using in situ surface temperature and soil surface moisture versus satellite estimates.

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

    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.

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

    Microsoft Academic Search

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

    2009-01-01

    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

  20. Effects of vegetation and soil moisture on the simulated land surface processes from the coupled WRF/Noah model

    E-print Network

    Small, Eric

    . Lakshmi, E. E. Small, F. Chen, M. Tewari, and K. W. Manning (2009), Effects of vegetation and soilEffects of vegetation and soil moisture on the simulated land surface processes from the coupled. Manning3 Received 5 October 2008; revised 14 March 2009; accepted 9 June 2009; published 24 September 2009

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

    E-print Network

    Flores, Alejandro N.

    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 ...

  2. Preliminary assessment of soil moisture over vegetation

    NASA Technical Reports Server (NTRS)

    Carlson, T. N.

    1986-01-01

    Modeling of surface energy fluxes was combined with in-situ measurement of surface parameters, specifically the surface sensible heat flux and the substrate soil moisture. A vegetation component was incorporated in the atmospheric/substrate model and subsequently showed that fluxes over vegetation can be very much different than those over bare soil for a given surface-air temperature difference. The temperature signatures measured by a satellite or airborne radiometer should be interpreted in conjunction with surface measurements of modeled parameters. Paradoxically, analyses of the large-scale distribution of soil moisture availability shows that there is a very high correlation between antecedent precipitation and inferred surface moisture availability, even when no specific vegetation parameterization is used in the boundary layer model. Preparatory work was begun in streamlining the present boundary layer model, developing better algorithms for relating surface temperatures to substrate moisture, preparing for participation in the French HAPEX experiment, and analyzing aircraft microwave and radiometric surface temperature data for the 1983 French Beauce experiments.

  3. Process-based modeling of vegetation dynamics, snow, evapotranspiration and soil moisture patterns in an alpine catchment

    NASA Astrophysics Data System (ADS)

    Bertoldi, Giacomo; Della Chiesa, Stefano; Engel, Michael; Niedrist, Georg; Brenner, Johannes G.; Endrizzi, Stefano; Dall'Amico, Matteo; Cordano, Emanuele; Tappeiner, Ulrike; Rigon, Riccardo

    2014-05-01

    Mountain regions are particularly sensitive to climate change and at the same time they represent a key water resource not only locally but as well for lowland areas. Because of the complexity of mountain landscapes and the high climatic variability at a local scale, detailed quantification of key water budget components as snow cover, soil moisture and groundwater recharge is required. Therefore, there is a strong need to improve the capability of hydrological models to identify patterns in complex terrain (i.e. when variability of spatial characteristics counts), and to quantify changes of the water cycle components explicitly, considering interactions and feedbacks with climate and vegetation. Process-based hydrological models represent promising tools for addressing those needs. However, even if their inherent complexity sometimes limits their applicability for operational purpose, they offer great potential in terms of tools to test hypotheses, which can be verified in the field. GEOtop is a hydrological model that calculates the energy and mass exchanges between soil, vegetation, and atmosphere, accounting for land cover, water redistribution, snow processes, glacier mass budget and the effects of complex terrain and thus is one of the few models that was built with this complexity in mind. Recently, it has also been coupled with a dynamic vegetation model in order to simulate alpine grassland ecosystems. In this contribution, we want to present an application of the GEOtop model in simulating above ground biomass (Bag) production, evapotranspiration (ET), soil moisture (SM) and snow water equivalent (SWE) patterns for a catchment of about 100 km2, located in the Venosta/Vinschgau valley in the European Alps. Despite the Alps are one of the 'water towers of Europe', water scarcity issues can affect the region where the model is applied, and an intensive hydrological and ecological monitoring activity with ground observations and remote-sensing products has been established in the last five years. Simulations results showed that, along south-facing slopes, ET and Bag did not decrease with elevation, as it happens along north facing slopes, but showed a maximum at an intermediate elevation around ca. 1500 m a.s.l., because of the contrasting trends of a shorter vegetation season at higher elevations and water stress at lower elevations. Therefore, results suggest that in this region south-facing pastures and woodlands below the elevation band of 1000 - 1500 m a.s.l. are the locations exposed to more frequent water stress conditions. Future climate change will likely worsen drought frequency. This contribution highlights that the collected data set permits a multi-scale and multi-process evaluation of the model. Plot scale observations of evapotranspiration, soil moisture and snow cover, combined with remote sensing observations of snow and soil moisture help to discriminate between uncertainties in input data (i.e. snow/rainfall partitioning) and model parameterization. Moreover, we want to show with practical examples how, when dealing with coupled process-based eco-hydrological models is essential considering the physical consistency between different processes as modeled in GEOtop. For example, accounting the role of subsurface water lateral distribution on surface soil moisture; considering both water and energy budget constrains; introducing the control of snow cover on vegetation phenology. This introduces additional constraints in model parameterization that allow a better understanding of some processes dynamics, and can lead to a more coherent and accurate estimation of the catchment hydrological behavior than the one, which is possible with simpler models.

  4. Parametrizing soil-vegetation-atmosphere transfer models with non-destructive and high resolution stable isotope data

    NASA Astrophysics Data System (ADS)

    Rothfuss, Youri; Vereecken, Harry; Brüggemann, Nicolas

    2015-04-01

    For nearly 50 years, stable isotopologues of water (1H2H16O and 1H218O) have been used in a wide range of water research disciplines to identify the origin and to quantify proportions of water pools involved in processes of the terrestrial water cycle. In soils between rain events, the combined action of convective capillary rise of water depleted in 1H2H16O and 1H218O with back-diffusion of water enriched in 1H2H16O and 1H218O from the evaporation site (i.e., soil surface or evaporation front) downwards leads to the formation of - typically exponential - soil water stable isotopologue profiles. The first steady state and isothermal analytical solutions of these isotopologues profiles were proposed in the late 60ies. They were later extended to unsteady state and non-isothermal conditions. These analytical formulations link the shape of the isotopologue profiles to soil evaporation flux and regime, and to the soil physical properties associated with both diffusive and convective water transport (such as tortuosity length and dispersivity). More recently, the movement of 1H2H16O and 1H218O was implemented in physically-based numerical soil-vegetation-atmosphere transfer (SVAT) models (e.g., TOUGHREACT, SiSPAT-Isotope, Soil-Litter iso, Hydrus 1D). In these fully coupled models, the output of the heat transfer module, i.e., the temperature profile, is fed into the isotope module. Isotope and water transport are therefore inter-dependent as opposed to analytical solutions. In addition to thermodynamic (equilibrium) isotope effects, which are only temperature-dependent, kinetic isotope effects during soil evaporation greatly affect the stable isotopic composition of soil water and evaporation and can be highly variable. Thus, a better understanding of the implications of these kinetic effects in addition to the well characterized equilibrium effects as well as their implementation in SVAT models are required for improving the use of 1H2H16O and 1H218O as tracers of soil water processes. An important challenge is to provide models with non-destructive and high resolution isotope data, both in space and time (e.g., using microporous tubing or membrane-based available setups). Moreover, parallel to field studies effort should be made to design specific experiments under controlled conditions, allowing for testing the underlying hypotheses of the above mentioned isotope-enabled SVAT models. Using isotope data obtained from these controlled experiments will improve the characterization of evaporation processes within the soil profile and ameliorate the parametrization of the respective isotope modules.

  5. Application of the Distributed Hydrology Soil Vegetation Model for Predicting Snowmelt Runoff in a Small, Steep Watershed in British Columbia

    NASA Astrophysics Data System (ADS)

    Dhakal, A. S.; Whyte, D.; Moore, R.; Toews, D.

    2002-12-01

    The Distributed Hydrology-Soil-Vegetation Model (DHSVM) is a physically based, distributed hydrology model that has been applied to snowmelt-fed mountain catchments in the Pacific Northwest for predicting the effects of forestry operations. Previous applications have focused on moderate to large catchments (from 26 km2 to about 3000 km2), but there appear to have been no applications of DHSVM to small mountain streams (watershed area < 1 km2) controlled by snow accumulation and melt. Such streams are important for domestic water supply in the interior of British Columbia, and the potential hydrologic impacts of forestry in these catchments generate significant concern and controversy. This study evaluates the performance of DHSVM during spring snowmelt in the Gurn Brook watershed located in the Slocan Valley, northwest of Nelson, BC. The watershed has a drainage area of 58 ha and ranges in elevation from 650 to 1600 m. Hillslopes mostly face west, with slope gradients exceeding 20 degrees over 77 percent of the catchment. Slopes are dominantly mantled by thin soils (typically less than 1 m deep) developed in colluvium overlying bedrock. The upper part of the watershed drains a concave (planform) slope that emerges into two ephemeral channels, which join and then flow through a narrow gully to the valley bottom. The digital elevation model (DEM) derived from a 1:5000 contour map with contour interval of 5 m formed the basic topographic data, which was also used to generate stream network. Preliminary evaluation of model performance suggests that explicit spatial quantification of soil, climatic and vegetation parameters appear to be much more important in smaller watersheds for accurate predictions of stream flow and snow cover distribution compared to larger watersheds, such as the nearby Redfish Creek, where DHSVM has previously been applied.

  6. MANAGING VEGETATION DYNAMICS: SOIL-GEOMORPHIC MAPS, STATE-AND-TRANSITION MODELS, AND REMOTE SENSING

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Vegetation mapping via remote sensing tools is a useful and cost-effective approach for understanding current land use and species habitat patterns, but has limited utility in predicting the future state of vegetation. We describe an approach that couples data-supported, conceptual state-and-transi...

  7. Modeling Spatial Patterns of Soil Respiration in Maize Fields from Vegetation and Soil Property Factors with the Use of Remote Sensing and Geographical Information System

    PubMed Central

    Huang, Ni; Wang, Li; Guo, Yiqiang; Hao, Pengyu; Niu, Zheng

    2014-01-01

    To examine the method for estimating the spatial patterns of soil respiration (Rs) in agricultural ecosystems using remote sensing and geographical information system (GIS), Rs rates were measured at 53 sites during the peak growing season of maize in three counties in North China. Through Pearson's correlation analysis, leaf area index (LAI), canopy chlorophyll content, aboveground biomass, soil organic carbon (SOC) content, and soil total nitrogen content were selected as the factors that affected spatial variability in Rs during the peak growing season of maize. The use of a structural equation modeling approach revealed that only LAI and SOC content directly affected Rs. Meanwhile, other factors indirectly affected Rs through LAI and SOC content. When three greenness vegetation indices were extracted from an optical image of an environmental and disaster mitigation satellite in China, enhanced vegetation index (EVI) showed the best correlation with LAI and was thus used as a proxy for LAI to estimate Rs at the regional scale. The spatial distribution of SOC content was obtained by extrapolating the SOC content at the plot scale based on the kriging interpolation method in GIS. When data were pooled for 38 plots, a first-order exponential analysis indicated that approximately 73% of the spatial variability in Rs during the peak growing season of maize can be explained by EVI and SOC content. Further test analysis based on independent data from 15 plots showed that the simple exponential model had acceptable accuracy in estimating the spatial patterns of Rs in maize fields on the basis of remotely sensed EVI and GIS-interpolated SOC content, with R2 of 0.69 and root-mean-square error of 0.51 µmol CO2 m?2 s?1. The conclusions from this study provide valuable information for estimates of Rs during the peak growing season of maize in three counties in North China. PMID:25157827

  8. Influence of vegetation on acoustic properties of soils

    Microsoft Academic Search

    L. A. M. Heijden; V. Claessen; N. Cock

    1983-01-01

    Possible influences of vegetation on acoustically relevant soil parameters, such as porosity and soil structure, were considered. In situ measurements of sound interference patterns were performed in seven plant communities by means of an inclined track method. Normal acoustical specific impedances were calculated with a plane wave outdoor sound propagation model. The impedances found generally showed a real part constant

  9. The Application and Performance of Two Soil-Vegetation-Atmosphere Modelling Platforms to a Real Hydrologic Catchment

    NASA Astrophysics Data System (ADS)

    Rihani, Jehan; Dahl Larsen, Morten Andreas; Stisen, Simon; Refsgaard, Jens Christian; Høgh Jensen, Karsten; Simmer, Clemens

    2013-04-01

    Land surface models are important in providing lower boundary fluxes and moisture for atmospheric models. Despite the increase in complexity and detailed representation of vegetation and root zone, LSMs remain for the most part one-dimensional column models which ignore lateral water flow at the land surface and within the top soil layers. In order to include processes effecting soil moisture variations such as shallow groundwater, runoff, overland flow, and subsurface lateral flow, a number of simulation platforms with varying complexity which couple groundwater, land surface, and atmospheric models have emerged. In this study, we compare two different integrated soil-vegetation-atmosphere modelling platforms: the ParFlow-CLM-COSMO model, developed within the Transregional Collaborative Research Centre (TR32), and the HIRHAM-MIKE SHE model, developed within the HOBE Centre for Hydrology and the HYdrological Modelling for Assessing Climate Change Impacts at differeNT Scales (HYACINTS) project. Both modelling platforms contain distributed, physically based, state-of-the-art components. ParFlow-CLM-COSMO consists of the variably saturated groundwater model ParFlow, the Community Land Model (CLM), and the regional climate and weather forecast model COSMO (German Weather Service, DWD). The HIRHAM-MIKE SHE model consists of the HIRHAM regional climate model (Danish Meteorological Institute), the SWET (Shuttleworth and Wallace Evapotranspiration) land-surface model, and the integrated hydrological model MIKE SHE (DHI). There are differences however between the two platforms in the handling of specific processes within the model components as well as differences in the coupling approach used. During the first part of the comparison study, we focus on the coupled subsurface-landsurface components offline from the atmosphere. One of the main differences in the handling of the subsurface component in both models is the inclusion of lateral flow in the unsaturated zone. In the MIKE SHE model, the 3D Richards' equation is used for the saturated subsurface region, while the 1D Richards' equation is used to simulate water flow in the unsaturated zone using simulated dynamic groundwater levels from its saturated zone module. ParFlow, on the other hand, includes both lateral and vertical flow by using the 3D Richards' equation for the subsurface to calculate the pressure field. This allows for lateral flows in the unsaturated zone. One of the main questions to be investigated by this comparison study is whether such a dynamic approach for the subsurface is needed within a real watershed, and if so, at which locations and times. The simulations for both platforms are established for the HOBE hydrologic observatory catchment in Denmark, the Skjern catchment. During the second part of this study, the comparison is extended to include the atmospheric components, which differ in the exchange of atmospheric forcing variables and surface moisture and energy fluxes, in fully coupled simulations. While ParFlow-CLM-COSMO utilizes an external coupler, HIRHAM-MIKE SHE implements a new OpenMI technology approach. The comparison study will highlight the effects and experiences of using different coupled model approaches on the simulated subsurface-land surface-atmosphere interactions within a real hydrologic catchment.

  10. Uptake of Organic Contaminants from Soil into Vegetables and Fruits

    Microsoft Academic Search

    Stefan Trapp; Charlotte N. Legind

    \\u000a Contaminants may enter vegetables and fruits by several pathways: by uptake with soil pore water, by diffusion from soil or\\u000a air, by deposition of soil or airborne particles, or by direct application. The contaminant-specific and plant-specific properties\\u000a that determine the importance of these pathways are described in this chapter. A variety of models have been developed, specific\\u000a for crop types

  11. Using the landscape evolution modelling framework Landlab to quantify how soils, climate, and vegetation are linked in semi-arid landscapes

    NASA Astrophysics Data System (ADS)

    Gelb, L.; Flores, A. N.; Yager, E.; Pierce, J. L.

    2014-12-01

    Soils are the interface between the lithosphere and the atmosphere. The presence and thickness of a soil mantle is locally a function of the rate of parent material weathering and the net transport of soil downslope, which are both heavily controlled by the type and density of vegetation present. In semiarid landscapes, water is often both a limiting material to the growth of vegetation as well as additional control on weathering and erosion of soil. The goal of our study is to promote fundamental understanding of the sensitivity of soil thickness to changes in precipitation in these water-limited environments. To accomplish this, we have quantified denudation rates in a semi-arid ecosystem through field work and used these data to inform a variety of climate change simulations in a landscape evolution model. Our denudation rates were sampled from areas with varying elevation, slope, and aspect, all variables that engender differences in the vegetation of sagebrush steppe ecosystems. The data were collected using a sediment flux measurement technique where a GPS with sub-centimeter accuracy was used to periodically resample the movement of rebar that was installed in the regolith. Within sagebrush steppe ecosystems, wildfires were historically common before the presence of humans. Contemporarily, after a disturbance invasive species are able to establish themselves more quickly than native plants can, and so fires have a much different effect on our landscapes than they did in the past. With Landlab, an open-source, community framework that supports the rapid development of integrated landscape development models, we have modeled the effect of this shift on landscape evolution. Our model is able to react to shifts in climate by changing the vegetation present and the recurrence interval of fires. We can, therefore, use the model to quantify the linkages between climate, local soil evolution, and landscape evolution under plausible alternative futures of climate.

  12. Effects of Vegetation Cover on the Radar Sensitivity to Soil Moisture

    Microsoft Academic Search

    Fawwaz T. Ulaby; Adnan Aslam; Myron C. Dobson

    1982-01-01

    Measurements of the backscattering coefficient ¿°, made for bare and vegetation-covered fields, are used in conjunction with a simple backscattering model to evaluate the effects of vegetation cover on the estimation accuracy of soil moisture when derived from radar observations. The results indicate that for soil moisture values below 50 percent of field capacity, the backscatter contribution of the vegetation

  13. Research progress on the effects of soil erosion on vegetation

    Microsoft Academic Search

    Juying Jiao; Houyuan Zou; Yanfeng Jia; Ning Wang

    2009-01-01

    The relationship between vegetation and soil erosion deserves attention due to its scientific importance and practical applications. A great deal of information is available about the mechanisms and benefits of vegetation in the control of soil erosion, but the effects of soil erosion on vegetation development and succession is poorly documented. Research shows that soil erosion is the most important

  14. The soil water balance in a mosaic of clumped vegetation

    NASA Astrophysics Data System (ADS)

    Pizzolla, Teresa; Manfreda, Salvatore; Caylor, Kelly; Gioia, Andrea; Iacobellis, Vito

    2014-05-01

    The spatio-temporal distribution of soil moisture influences the plant growth and the distribution of terrestrial vegetation. This effect is more evident in arid and semiarid ecosystems where the interaction between individuals and the water limited conditions play a fundamental role, providing environmental conditions which drive a variety of non-linear ecohydrological response functions (such as transpiration, photosynthesis, leakage). In this context, modeling vegetation patterns at multiple spatial aggregation scales is important to understand how different vegetation structures can modify the soil water distribution and the exchanged fluxes between soil and atmosphere. In the present paper, the effect of different spatial vegetation patterns, under different climatic scenarios, is investigated in a patchy vegetation mosaic generated by a random process of individual tree canopies and their accompanying root system. Vegetation pattern are generated using the mathematical framework proposed by Caylor et al. (2006) characterized by a three dimensional stochastic vegetation structure, based on the density, dispersion, size distribution, and allometry of individuals within a landscape. A Poisson distribution is applied to generate different distribution of individuals paying particular attention on the role of clumping on water distribution dynamics. The soil water balance is evaluated using the analytical expression proposed by Laio et al. (2001) to explore the influence of climate and vegetation patterns on soil water balance steady-state components (such as the average rates of evaporation, the root water uptake and leakage) and on the stress-weighted plant water uptake. Results of numerical simulations show that clumping may be beneficial for water use efficiency at the landscape scale. References Caylor, Kelly K., P. D'Odorico and I. Rodriguez Iturbe: On the ecohydrology of structurally heterogeneous semiarid landscape. Water Resour. Res., 28, W07424, 2006. Laio, F., A. Porporato, L., Ridolfi and I. Rodriguez Iturbe: Plants in water controlled ecosystems: Active role in hydrological processes and response to water stress, II. Probabilistic soil moisture dynamics, Adv. Water Resour., 24(7), 707-723,2001.

  15. Integrating models to simulate emergent behaviour: effects of organic matter on soil hydraulics in the ICZ-1D soil-vegetation model

    NASA Astrophysics Data System (ADS)

    Valstar, Johan; Rowe, Ed; Konstantina, Moirogiorgou; Giannakis, Giorgos; Nikolaidis, Nikolaos

    2014-05-01

    Soil develops as a result of interacting processes, many of which have been described in more or less detailed models. A key challenge in developing predictive models of soil function is to integrate processes that operate across a wide range of temporal and spatial scales. Many soil functions could be classified as "emergent", since they result from the interaction of subsystems. For example, soil organic matter (SOM) dynamics are commonly considered in relation to carbon storage, but can have profound effects on soil hydraulic properties that are conventionally considered to be static. Carbon fixed by plants enters the soil as litterfall, root turnover or via mycorrhizae. Plants need water and nutrients to grow, and an expanding root system provides access to a larger volume of soil for uptake of water and nutrients. Roots also provide organic exudates, such as oxalate, which increase nutrient availability. Carbon inputs are transformed at various rates into soil biota, CO2, and more persistent forms of organic matter. The SOM is partly taken up into soil aggregates of variable sizes, which slows down degradation. Water availability is an important factor as both plant growth and SOM degradation can be limited by shortage of water. Water flow is the main driver for transport of nutrients and other solutes. The flow of water in turn is influenced by the presence of SOM as this influences soil water retention and hydraulic conductivity. Towards the top of the unsaturated zone, bioturbation by the soil fauna transports both solid material and solutes. Weathering rates of minerals determine the availability of many nutrients and are in turn dependent on parameters such as pH, water content, CO2 pressure and oxalate concentration. Chemical reactions between solutes, dissolution and precipitation, and exchange on adsorption sites further influence solute concentrations. Within the FP7 SoilTrEC project, we developed a model that incorporates all of these processes, to explore the complex interactions involved in soil development and change. We were unable to identify appropriately-detailed existing models for plant productivity and for the dynamics of soil aggregation and porosity, and so developed the PROSUM and CAST models, respectively, to simulate these subsystems. Moreover, we applied the BRNS generator to obtain a chemical equilibrium model. These were combined with HYDRUS-1D (water and solute transport), a weathering model (derived from the SAFE model) and a simple bioturbation model. The model includes several feedbacks, such as the effect of soil organic matter on water retention and hydraulic conductivity. We encountered several important challenges when building the integrated model. First, a mechanism was developed that initiates the execution of a single time step for an individual sub-model and accounts for the relevant mass transfers between sub-models. This allows for different and sometimes variable time step duration in the submodels. Secondly, we removed duplicated processes and identified and included relevant solute production terms that had been neglected. The model is being tested against datasets obtained from several Soil Critical Zone Observatories in Europe. This contribution focuses on the design strategy for the model.

  16. Improving Soil-Vegetation Dynamics in the Soil and Water Assessment Tool (SWAT)

    NASA Astrophysics Data System (ADS)

    Ou, G.; Munoz-Arriola, F.; Chen, X.; Kilic, A.

    2014-12-01

    A non-iterative 1D Richard's equation model is developed and implemented in the Soil and Water Assessment Tool (SWAT) to improve the physical representation of soil-water-vegetation dynamics. SWAT's improved version (UN-SWAT) explicitly represents infiltration, soil evaporation, unsaturated water flow, root water update, and lateral drainage. Water-exchanges across the surface-subsurface and unsaturated-saturated zone interfaces are defined as the system's dependent top and bottom boundaries of the soil profile, respectively. In the continuum from the land surface to the aquifer, the top boundary of the soil profile accounts for non-ponding or ponding infiltration, as well as atmosphere-controlled or soil-controlled evaporation. Vegetation's root water update and lateral drainage are represented as sink terms in each soil layer. The soil profile is discretized by a variable number of computational nodes of the soil profile, whose bottom position is determined based on the groundwater table. UN-SWAT validation is performed by a single-HRU and a multi-HRU simulations in the Little Washita River Experimental Watershed in Oklahoma. Results prove that UN-SWAT's performance simulating the soil water movement in both space and time under complex conditions agree observed soil moisture and stream discharge data. UN-SWAT represents an improvement over other hydrologic models by providing a more accurate solution to the soil-water-vegetation model and accounting for the dynamics of climate and groundwater conditions.

  17. The study of soils and vegetation transformation due fire disturbances in remote areas through scenario modelling of observed hydrological response to fire impact

    NASA Astrophysics Data System (ADS)

    Nesterova, Natalia; Semenova, Olga; Lebedeva, Luidmila

    2015-04-01

    Large territories of Siberia and Russian Far East are the subject to frequent forest fires. Often there is no information available about fire impact except its timing, areal distribution and qualitative characteristics of fire severity. Observed changes of hydrological response in burnt watersheds can be considered as indirect evidence of soil and vegetation transformation due to fire impact. In our study we used MODIS Fire products to detect spatial distribution of fires in Transbaikal and Far East regions of Russia in 2000 - 2012 period. Small and middle-size watersheds (with area up to 10000 km2) affected by extensive (burn area not less than 20 %) fires were chosen. We analyzed available hydrological data (measured discharges in watersheds outlets) for chosen basins. In several cases apparent hydrological response to fire was detected. To investigate main factors causing the change of hydrologic regime after fire several scenarios of soil and vegetation transformation were developed for each watershed under consideration. Corresponding sets of hydrological model parameters describing those transformations were elaborated based on data analysis and post-fire landscape changes as derived from a literature review. We implied different factors such as removal of organic layer, albedo changes, intensification of soil thaw (in presence of permafrost and seasonal soil freezing), reduction of infiltration rate and evapotranspiration, increase of upper subsurface flow fraction in summer flood events following the fire and others. We applied Hydrograph model (Russia) to conduct simulation experiments aiming to reveal which landscape changes scenarios were more plausible. The advantages of chosen hydrological model for this study are 1) that it takes into consideration thermal processes in soils which in case of permafrost and seasonal soil freezing presence can play leading role in runoff formation and 2) that observable vegetation and soil properties are used as its parameters allowing minimal resort to calibration. The model can use dynamic set of parameters performing preassigned abrupt and/or gradual changes of landscape characteristics. Interestingly, based on modelling results it can be concluded that depending on dominant landscape different aspects of soil and vegetation cover changes may influence runoff formation in contrasting way. The results of the study will be reported.

  18. Bowen ratio measurements above various vegetation covers and its comparison with actual evapotranspiration estimated by SoilClim model

    NASA Astrophysics Data System (ADS)

    Hlavinka, P.; Trnka, M.; Fischer, M.; Kucera, J.; Mozny, M.; Zalud, Z.

    2010-09-01

    The principle of Bowen ratio is one of the available techniques for measurements of actual evapotranspiration (ETa) as one of essential water balance fractions. The main aims of submitted study were: (i) to compare the water balance of selected crops, (ii) to compare outputs of SoilClim model with observed parameters (including ETa on Bowen ratio basis). The measurements were conducted at two experimental stations in the Czech Republic (Polkovice 49°23´ (N), 17°17´ (E), 205 m a.s.l.; Domanínek 49°32´ (N), 16°15´ (E), 544 m a.s.l.) during the years 2009 and 2010. Together with Bowen ratio the global solar radiation, radiation balance, soil heat flux, volumetric soil moisture and temperature within selected depths, precipitation and wind speed were measured. The measurements were conducted simultaneously above various covers within the same soil conditions: spring barley vs. winter wheat, spring barley vs. winter rape; grass vs. poplars; harvested field after tillage vs. harvested field after cereals without any tillage. The observed parameters from different covers were compared with SoilClim estimates. SoilClim model is modular software for water balance and soil temperature modelling and finally could be used for soil Hydric and Thermic regimes (according to USDA classification) identification. The core of SoilClim is based on modified FAO Penman-Monteith methodology. Submitted study proved the applicability of SoilClim model for ETa, soil moisture within two defined layers and soil temperature (in 0.5 m depth) estimates for various crops, covers, selected soil types and climatic conditions. Acknowledgement: We gratefully acknowledge the support of the Grant Agency of the Czech Republic (no. 521/09/P479) and the project NAZV QI91C054. The study was also supported by Research plan No. MSM6215648905 "Biological and technological aspects of sustainability of controlled ecosystems and their adaptability to climate change".

  19. Calculations of radar backscattering coefficient of vegetation-covered soils

    NASA Technical Reports Server (NTRS)

    Mo, T.; Schmugge, T. J.; Jackson, T. J.

    1984-01-01

    The present investigation has the objective to develop a simple 'user's' model for simulating the measured radar backscattering coefficients from vegetation-covered fields in conjunction with the data obtained by Jackson et al. (1980, 1982). The theoretical work reported by Fung and Eom (1981) provides the basis for the model. Certain modifications are related to a consideration of the effect of a vegetation canopy. The first part of the model is concerned with a description of scatter from rough bare soil, while the second part takes into account the effect of a vegetation cover. It is shown that the measured angular distribution of the backscattering coefficient of vegetation-covered fields can be satisfactory reproduced by using the developed model.

  20. Calculations of radar backscattering coefficient of vegetation-covered soils

    NASA Technical Reports Server (NTRS)

    Mo, T.; Schmugge, T. J.; Jackson, T. J. (principal investigators)

    1983-01-01

    A model for simulating the measured backscattering coefficient of vegetation-covered soil surfaces includes both coherent and incoherent components of the backscattered radar pulses from a rough sil surface. The effect of vegetation canopy scattering is also incorporated into the model by making the radar pulse subject to two-way attenuation and volume scattering when it passes through the vegetation layer. Model results agree well with the measured angular distributions of the radar backscattering coefficient for HH polarization at the 1.6 GHz and 4.75 GHz frequencies over grass-covered fields. It was found that the coherent scattering component is very important at angles near nadir, while the vegetation volume scattering is dominant at incident angles 30 degrees.

  1. A Coupled VegetationSoil Bidirectional Reflectance Model for a Semiarid Landscape

    E-print Network

    Ni-Meister, Wenge

    distribution function (BRDF), which is definedvery simple but analytical model for bidirectional reflec for given direction to the incident irradiance (radiant powersurface parameter retrieval for the study of biosphere­ per unit area of surface) (Nicodemus et al., 1977):atmosphere interaction. ©Elsevier Science Inc

  2. The Influence of Soil and Vegetation on the Development of Mesoscale Circulations

    Microsoft Academic Search

    Jean-François Mahfouf; Evelyne Richard; Patrick Mascart

    1987-01-01

    A two-dimensional mesoscale model including a detailed representation of the planetary boundary layer, the soil and the vegetation is developed. A sea breeze over flat terrain is simulated, thereby confirming the ability of the model to reproduce the known properties of this mesoscale phenomenon. The atmospheric response to soil and vegetation inhomogeneities is then examined with no synoptic flow over

  3. Biophysical Interpretation of Spectral Indices for Semi-Arid Soil and Vegetation Types in Niger.

    NASA Astrophysics Data System (ADS)

    van Leeuwen, Willem Jan Dirk

    1995-05-01

    In situ radiometric field data and data simulated with a radiative transfer model were used to evaluate the performance and biophysical interpretation of spectral indices. Concurrently with remotely sensed measurements, temporal biophysical measurements for different vegetation types for two semi-arid regions in Niger were made, including leaf area index (LAI), fraction of absorbed photosynthetically active radiation (fAPAR), percent vegetation cover, and biomass. The spectral dynamics of vegetation and soil were characterized at the leaf and canopy scale by optical measurements under many adverse conditions, including variability in vegetation optical and structural properties, soil reflectance properties, sun and view geometry and atmospheric perturbations. The spectral indices evaluated in this research comprised spectral vegetation indices and spectral mixture model indices, computed from spectral reflectances. The performance of different vegetation indices and their sensitivity to green and non-green vegetation and soils were compared and quantified by utilizing estimates of percent relative error in spectral vegetation indices, and estimates of vegetation equivalent noise expressed in terms of biophysical parameters (LAI, fAPAR). The soil adjusted vegetation index (SAVI) and modified normalized vegetation index (MNDVI) were improvements over the normalized difference vegetation index (NDVI), but were still sensitive to many perturbing variables such as soil and vegetation distribution, soil optical properties, litter and green vegetation optical properties and leaf angle distribution. The spectral mixture model indices were designed to be sensitive to vegetation, soil and non-green vegetation components and were shown to provide useful surface information that can aid in minimizing the noise in spectral vegetation indices, and also in improving their biophysical interpretation. Vegetation and soil brightness imagery were created from remotely sensed reflectance data, by calibrating the spectral mixture model with the data generated with a radiative transfer model. The effect of standing litter on spectral indices was shown to possibly cause both an increase and a decrease in the vegetation index, depending on the coupled spectral and structural properties of litter, green vegetation and soil. In situ measurements confirmed the results obtained from the analysis of data sets generated with a radiative transfer model. The implications of the effect of perturbing variables on spectral indices were also discussed.

  4. 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...

  5. Soil water availability as controlling factor for actual evapotranspiration in urban soil-vegetation-systems

    NASA Astrophysics Data System (ADS)

    Thomsen, Simon; Reisdorff, Christoph; Gröngröft, Alexander; Jensen, Kai; Eschenbach, Annette

    2015-04-01

    The City of Hamburg is characterized by a large number of greens, parks and roadside trees: 600.000 trees cover about 14% of the city area, and moreover, 245.000 roadside trees can be found here. Urban vegetation is generally known to positively contribute to the urban micro-climate via cooling by evapotranspiration (ET). The water for ET is predominantly stored in the urban soils. Hence, the actual evapotranspiration (ETa) is - beside atmospheric drivers - determined by soil water availability at the soil surface and in the rooting zones of the respective vegetation. The overall aim of this study is to characterize soil water availability as a regulative factor for ETa in urban soil-vegetation systems. The specific questions addressed are: i) What is the spatio-temporal variation in soil water availability at the study sites? ii) Which soil depths are predominantly used for water uptake by the vegetation forms investigated? and iii) Which are the threshold values of soil water tension and soil water content (?), respectively, that limit ETa under dry conditions on both grass-dominated and tree-dominated sites? Three study areas were established in the urban region of Hamburg, Germany. We selected areas featuring both single tree stands and grass-dominated sites, both representing typical vegetation forms in Hamburg. The areas are characterized by relatively dry soil conditions. However, they differ in regard to soil water availability. At each area we selected one site dominated by Common Oak (Quercus ruber L.) with ages from 40 to 120 years, and paired each oak tree site with a neighboring grass-dominated site. All field measurements were performed during the years 2013 and 2014. At each site, we continuously measured soil water tension and ? up to 160 cm depth, and xylem sap flux of each of three oak trees per site in a 15 min-resolution. Furthermore, we measured soil hydraulic properties as pF-curve, saturated and unsaturated conductivity at all sites. Automated weather stations for the continuous measurement of all relevant climatic factors were established at all grass-dominated sites. Based on the field data, soil water balances were simulated for all sites with the HYDRUS model. Potential ET for the grass-dominated sites was calculated using the Penman-Monteith equation. Results regarding the spatio-temporal variability of available soil water of the study sites will be shown and discussed in this contribution. Moreover, correlations between soil water availability and ETa will be presented.

  6. Analysis of co-evolving soil depths, vegetation patterns, and connectivity on drylands.

    NASA Astrophysics Data System (ADS)

    Saco, Patricia; Willgoose, Garry

    2014-05-01

    Arid and semiarid landscapes cover more than 30% of the Earth's surface. Vegetation in these areas is usually patchy due limited resource availability. This self-organized patchiness results from the nonlinear feedbacks between water redistribution, soils, landforms, and biota. These complex interactions make the understanding and prediction of landscape responses to climate and land use change highly challenging. Though several models have been recently developed and used to understand these feedbacks and the emergence of vegetation patterns in drylands, these models do not explicitly incorporate feedbacks with coevolving soil depths. Here we analyse feedback effects resulting from co-evolving soil depths, which play a key role in the redistribution of surface runoff and therefore on the patterns of vegetation and landscape connectivity. We present modelling results using a coupled landform evolution-dynamic vegetation model, which includes a soil depth evolution module accounts and for soil production and sediment erosion and deposition processes. We analyse the co-evolution of soil depths and vegetation patterns for varying soil erodibilities, slopes and plant functional types. We find that for deeper soils, facilitation effects of vegetation gives rise to the formation of regular patterns, and slope and soil erodibility are the key factors for recovery after disturbance. Disturbances in areas with high slope and/or soil erodibility lead to an increase in connectivity and a degraded state. In contrast, we find that for shallow soils, the facilitation effect of vegetation becomes less important and vegetation patterns are more irregular. In this case, soil depth becomes the key factor prescribing surface connectivity and for the recovery of the system after disturbance. These results have critical implications for effective management and restoration efforts, and for understanding the effects of changes in climate and land use.

  7. Modeling aeolian erosion in presence of vegetation

    NASA Astrophysics Data System (ADS)

    Dupont, S.; Bergametti, G.; Simoëns, S.

    2014-02-01

    Semiarid landscapes are characterized by vegetated surfaces. Understanding the impact of vegetation on aeolian soil erosion is important for reducing soil erosion or limiting crop damage through abrasion or burial. In the present study, a saltation model fully coupled with a large-eddy simulation airflow model is extended to vegetated landscapes. From this model, the sensitivity of sand erosion to different arrangements and type of plants (shrub versus tree) representative of semiarid landscapes is investigated and the wind erosion reduction induced by plants is quantified. We show that saltation processes over vegetated surfaces have a limited impact on the mean wind statistics, the momentum extracted from the flow by saltating particles being negligible compared to that extracted by plants. Simulated sand erosion patterns resulting from plant distribution, i.e., accumulation and erosion areas, appear qualitatively consistent with previous observations. It is shown that sand erosion reduction depends not only on vegetation cover but also on plant morphology and plant distribution relative to the mean wind direction. A simple shear stress partitioning approach applied in shrub cases gives similar trends of sand erosion reduction as the present model following wind direction and vegetation cover. However, the magnitude of the reduction appears significantly different from one approach to another. Although shrubs trap saltating particles, trees appear more efficient than shrubs to reduce sand erosion. This is explained by the large-scale sheltering effect of trees compared to the local shrub one.

  8. Passive Microwave Soil Moisture Disaggregation radar data and relationship between soil moisture, vegetation and surface temperature

    NASA Astrophysics Data System (ADS)

    Lakshmi, Venkat; Fang, Bin

    2014-05-01

    Soil moisture is an important variable in weather and climate. The passive microwave sensors have provided soil moisture of various spatial resolutions and are available for all-weather conditions, including AMSR-E (Advanced Microwave Scanning Radiometer- Earth Observing System), AMSR2 (Advanced Microwave Scanning Radiometer 2) and SMOS (Soil Moisture and Ocean Salinity). However, the spatial resolution of passive microwave soil moisture product is restricted at tens of kilometers level and needs to be improved. Toward this issue, the SMAP (Soil Moisture Active Passive) is set to be launched in October 2014 will be the first mission to provide L-band radar/radiometer soil moisture retrievals at three resolutions. In this paper we present two distinct methods to obtain higher spatial resolution soil moisture. The first one is use of active radar data to downscale soil moisture obtained by passive radiometers. The SMAP Validation Experiment 2012 (SMAPVEX12) was taken place and provided Passive/Active L-band Sensor (PALS) observations of two along-track resolutions (650 m and 1590 m), as well as ground soil moisture measurements. Consequently the PALS data can be used for disaggregating coarse resolution passive soil moisture retrievals. Based on a change detection theory, the relationships between change in radar backscatter and change in soil moisture at both coarse and fine resolutions are examined and used for calculating high spatial resolution soil moisture from AMSR-E and SMOS. Using SMAPVEX12 ground measurements validates the disaggregation results. The second method is use of the relationship between vegetation and surface temperature to downscale soil moisture obtained from passive radiometers. The physical relationships amongst soil moisture, land surface temperature and vegetation index (Normalized Difference Vegetation Index, NDVI), the historic soil moisture data of recent 30 years at 1/8 degree NLDAS (North America Land Data Assimilation Systems) scale were studied and modeled by using the long term records of land surface model and remote sensing products, NLDAS, MODIS (Moderate Resolution Imaging Spectroradiometer) and AVHRR (Advanced Very High Resolution Radiometer). This modeled relationship was then applied to the 1 km MODIS land surface temperature for disaggregating the microwave soil moisture estimates AMSR-E and SMOS in Oklahoma. Two sets of in-situ measurements Oklahoma Mesonet and Little Washita watershed Micronet were used for validating the disaggregated soil moisture.

  9. Response of spectral vegetation indices to soil moisture in grasslands and shrublands

    USGS Publications Warehouse

    Zhang, L.; Ji, L.; Wylie, B.K.

    2011-01-01

    The relationships between satellite-derived vegetation indices (VIs) and soil moisture are complicated because of the time lag of the vegetation response to soil moisture. In this study, we used a distributed lag regression model to evaluate the lag responses of VIs to soil moisture for grasslands and shrublands at Soil Climate Analysis Network sites in the central and western United States. We examined the relationships between Moderate Resolution Imaging Spectroradiometer (MODIS)-derived VIs and soil moisture measurements. The Normalized Difference Vegetation Index (NDVI) and Normalized Difference Water Index (NDWI) showed significant lag responses to soil moisture. The lag length varies from 8 to 56 days for NDVI and from 16 to 56 days for NDWI. However, the lag response of NDVI and NDWI to soil moisture varied among the sites. Our study suggests that the lag effect needs to be taken into consideration when the VIs are used to estimate soil moisture. ?? 2011 Taylor & Francis.

  10. Spontaneous development of urban woody vegetation on differing soils

    Microsoft Academic Search

    Reinhard Bornkamm

    2007-01-01

    The general aim of the study was to follow the development of spontaneous woody vegetation on man-made urban habitats in Berlin, Germany. In spring 1968, the vegetation was removed completely in five groups of plots, which had been filled with five different transferred soil material in 1928. The spontaneous vegetation was monitored annually from 1968 to 2006. Especially, the development

  11. Modeling Vegetable Oil Viscosity

    Microsoft Academic Search

    M. Balat

    2008-01-01

    Vegetable oils have become more attractive recently because of their environmental benefits and the fact that it is made from renewable resources. Vegetable oils do not contain any sulfur, aromatic hydrocarbons, metals, or crude oil residues. Short-term engine tests indicate good potential for vegetable oil fuels. Long-term endurance tests may show serious problems in injector coking, ring sticking, gum formation,

  12. Dual frequency microwave radiometer measurements of soil moisture for bare and vegetated rough surfaces

    NASA Technical Reports Server (NTRS)

    Lee, S. L.

    1974-01-01

    Controlled ground-based passive microwave radiometric measurements on soil moisture were conducted to determine the effects of terrain surface roughness and vegetation on microwave emission. Theoretical predictions were compared with the experimental results and with some recent airborne radiometric measurements. The relationship of soil moisture to the permittivity for the soil was obtained in the laboratory. A dual frequency radiometer, 1.41356 GHz and 10.69 GHz, took measurements at angles between 0 and 50 degrees from an altitude of about fifty feet. Distinct surface roughnesses were studied. With the roughness undisturbed, oats were later planted and vegetated and bare field measurements were compared. The 1.4 GHz radiometer was less affected than the 10.6 GHz radiometer, which under vegetated conditions was incapable of detecting soil moisture. The bare surface theoretical model was inadequate, although the vegetation model appeared to be valid. Moisture parameters to correlate apparent temperature with soil moisture were compared.

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

    PubMed

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

    2009-01-01

    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. PMID:22408527

  14. Soil, biomass, and management of semi-natural vegetation

    Microsoft Academic Search

    Part I. Interrelationships; P. Schaffers

    2002-01-01

    The interrelationships between biomass characteristics and soil properties (including in situ annual nitrogen mineralization) were statistically investigated in a descriptive study using a broad range of plant communities in unfertilized road verges. Not only the dependence of biomass characteristics on soil properties, but also the possibility of inferring soil nutrient availability from biomass characteristics was investigated. Possible effects of vegetation

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

    Microsoft Academic Search

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

    2007-01-01

    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

  16. The tri-soil experiment: do plants discriminate among vegetation soil types?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We tested if rooting mass and root nutrient uptake of cheatgrass (Bromus tectorum) or creeping wildrye (Leymus triticoides) were influenced by vegetation soil type. Three soil types (A horizons), similar in gross physical and chemical properties, were freshly-collected. The soils varied in the veget...

  17. Estimation of Soil Moisture for Vegetated Surfaces Using Multi-Temporal L-Band SAR Measurements

    NASA Technical Reports Server (NTRS)

    Shi, Jian-Cheng; Sun, G.; Hsu, A.; Wang, J.; ONeill, P.; Ranson, J.; Engman, E. T.

    1997-01-01

    This paper demonstrates the technique to estimate ground surface and vegetation scattering components, based on the backscattering model and the radar decomposition theory, under configuration of multi-temporal L-band polarimetric SAR measurement. This technique can be used to estimate soil moisture of vegetated surface.

  18. The Effect of Vegetation on Soil Moisture Retrievals from GPS Signal-to-Noise Ratio Data

    NASA Astrophysics Data System (ADS)

    Chew, C. C.; Small, E. E.; Larson, K. M.; Zavorotny, V.

    2012-12-01

    GPS-Interferometric Reflectometry (GPS-IR) is a method of environmental monitoring that relates changes in ground-reflected (multipath) GPS signals to changes in surface soil moisture and vegetative state for an area of approximately 1000 m2 surrounding a GPS antenna. GPS-IR operates as a bi-static radar: L2C frequency signals transmitted by GPS satellites and subsequent reflections (multipath) are measured by antennas at permanent GPS stations. Changes in multipath signals are seen in signal-to-noise ratio (SNR) interferograms, which are recorded by the GPS receiver. Results from previous field studies have shown that shallow soil moisture can be estimated from SNR phase for bare soil conditions or when vegetation is sparse. Vegetation surrounding a GPS antenna affects the phase shift, amplitude, and frequency/apparent reflector height of SNR oscillations. Therefore, it is necessary to quantify the vegetation conditions, for example vegetation height or water content, that preclude retrieval of soil moisture estimates using GPS-IR. We use both field data and an electrodynamic model that simulates SNR interferograms for variable soil and vegetation conditions to: 1. Determine how changes in vegetation height, biomass, and water content affect GPS phase, amplitude, and apparent reflector height and 2. Quantify the amount of vegetation that obscures the soil moisture signal in SNR data. We report results for rangeland and agricultural sites. At the rangeland sites, vegetation water content only varies between 0 and 0.6 kg/m2. Both observed and simulated SNR data from these sites show that apparent reflector height is nearly constant. Therefore, SNR interferograms are strongly affected by permittivity at the soil surface, and thus soil moisture can be retrieved. Even though reflector height does not change, SNR phase shift and amplitude are affected by fluctuations in rangeland vegetation and must be accounted for in soil moisture retrievals. At several agricultural sites, apparent reflector height decreases as vegetation grows, although the primary reflector is not an indicator of vegetation canopy height. SNR data is significantly affected by reflections within the vegetation canopy when the canopy permittivity is high, which is the result of a combination of both vegetation water content and canopy height. Under these conditions, estimates of SNR phase shift and amplitude have larger errors; thus, soil moisture retrieval may not be possible using phase shift or amplitude alone.

  19. Radar reflectivity of bare and vegetation-covered soil

    NASA Technical Reports Server (NTRS)

    Ulaby, F. T.; Dobson, M. C.; Bradley, G. A.

    1981-01-01

    Radar sensitivity to soil moisture content has been investigated experimentally for bare and vegetation-covered soil using detailed spectral measurements obtained by a truck-mounted radar spectrometer in the 1-8 GHz band and by airborne scatterometer observations at 1.6, 4.75, and 13.3 GHz. It is shown that radar can provide quantitative information on the soil moisture content of both bare and vegetation-covered soil. The observed soil moisture is in the form of the soil matric potential or a related quantity such as the percent of field capacity. The depth of the monitored layer varies from 1 cm for very wet soil to about 15 cm for very dry soil.

  20. Remote measurement of soil moisture over vegetation using infrared temperature measurements

    NASA Technical Reports Server (NTRS)

    Carlson, Toby N.

    1991-01-01

    Better methods for remote sensing of surface evapotranspiration, soil moisture, and fractional vegetation cover were developed. The objectives were to: (1) further develop a model of water movement through the soil/plant/atmosphere system; (2) use this model, in conjunction with measurements of infrared surface temperature and vegetation fraction; (3) determine the magnitude of radiometric temperature response to water stress in vegetation; (4) show at what point one can detect that sensitivity to water stress; and (5) determine the practical limits of the methods. A hydrological model that can be used to calculate soil water content versus depth given conventional meteorological records and observations of vegetation cover was developed. An outline of the results of these initiatives is presented.

  1. Earthworm-vegetation-soil relationships in the Romanian Carpathians

    Microsoft Academic Search

    Victor V. Pop

    1997-01-01

    The structure of six earthworm community patterns, labelled by the name of the characteristic species, is presented. In forest ecosystems the earthworm communities are characteristic for classes of vegetation (coniferous, beech, beech-hornbeam and oak-hornbeam), while in grasslands they correspond to alliances related by their trophicity (eu-, mezobasic, oligobasic). A table shows the earthworm-vegetation-soil relationships.

  2. SOIL AND VEGETATIVE COVERS FOR LEAD (PB) MINE WASTE PILES

    EPA Science Inventory

    Conduct vegetation studies that evaluate a variety of seed mixtures and surface amendments (soil, compost, biosolids, yard waste and fertilizers). US Bureau of Reclamation with experts formerly with US Bureau of Mines to contribute to Vegetation Plan for Big River NTCR EE/CA ...

  3. Uncertainty Analysis on Quantities Predicted by the Hydro - Thermodynamic Soil Vegetation Scheme (HTSVS)

    Microsoft Academic Search

    Amy Rulo; Nicole Mölders

    This paper discusses an uncertainty analysis preformed on a soil vegetation atmosphere transfer scheme described in Kramm et al. (1996). The effects of using several uncertain but required parameters in the prediction equations were estimated using Gaussian Error Propagation. The analysis considered the effects on the model prediction with respect to certain soil and atmospheric conditions that were varied over

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

    Microsoft Academic Search

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

    2006-01-01

    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

  5. 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)

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

    2008-06-01

    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.

  6. Soil permeability as a function of vegetation type and soil water content

    SciTech Connect

    Morris, R.C.; Fraley, L. Jr. [Colorado State Univ., Fort Collins, CO (United States)

    1994-06-01

    Soil permeability is important for estimating the rate of mass transport of {sup 222}Rn through soils and into basements. We measured permeability and soil water content on a set of nine plots consisting of three plots vegetated with common barley (Hordeum vulgare), three plots vegetated with Russian thistle (Salsola kali), and three bare plots. Soil moisture was consistently highest on the bare plots and lowest on the Russian thistle plots. Plots with vegetation had lower soil water content during the growing season. Permeability was consistently higher on Russian thistle plots. ANOVA showed that both soil water content and presence of Russian thistle had a significant impact on permeability but that presence of barley did not. The effect of vegetation and moisture on permeability may have significant effects on {sup 222}Rn transport in soils. 18 refs., 8 figs., 1 tab.

  7. Influences of soil moisture and vegetation on convective precipitation forecasts over the United States Great Plains

    NASA Astrophysics Data System (ADS)

    Collow, Thomas W.; Robock, Alan; Wu, Wei

    2014-08-01

    This study investigates the influences of soil moisture and vegetation on 30 h convective precipitation forecasts using the Weather Research and Forecasting model over the United States Great Plains with explicit treatment of convection. North American Regional Reanalysis (NARR) data were used as initial and boundary conditions. We also used an adjusted soil moisture (uniformly adding 0.10 m3/m3 over all soil layers based on NARR biases) to determine whether using a simple observationally based adjustment of soil moisture forcing would provide more accurate simulations and how the soil moisture addition would impact meteorological parameters for different vegetation types. Current and extreme (forest and barren) land covers were examined. Compared to the current vegetation cover, the complete removal of vegetation produced substantially less precipitation, while conversion to forest led to small differences in precipitation. Adding 0.10 m3/m3 to the soil moisture with the current vegetation cover lowered the near surface temperature and increased the humidity to a similar degree as using a fully forested domain with no soil moisture adjustment. However, these temperature and humidity effects on convective available potential energy and moist enthalpy nearly canceled each other out, resulting in a limited precipitation response. Although no substantial changes in precipitation forecasts were found using the adjusted soil moisture, the similarity found between temperature and humidity forecasts using the increased soil moisture and those with a forested domain highlights the sensitivity of the model to soil moisture changes, reinforcing the need for accurate soil moisture initialization in numerical weather forecasting models.

  8. Dieldrin uptake by vegetable crops grown in contaminated soils

    Microsoft Academic Search

    Lucia Donnarumma; Valter Pompi; Alessandro Faraci; Elisa Conte

    2009-01-01

    The aim of these trials was to study the distribution of dieldrin in soil and its translocation to roots and the aerial parts of vegetable crops grown in greenhouses and fields. The main objectives were to characterize dieldrin accumulation in plant tissues in relation to the levels of soil contamination; uptake capability among plants belonging to different species, varieties and

  9. Natural and anthropogenic lead in soils and vegetables around Guiyang city, southwest China: a Pb isotopic approach.

    PubMed

    Li, Fei-Li; Liu, Cong-Qiang; Yang, Yuan-Gen; Bi, Xiang-Yang; Liu, Tao-Ze; Zhao, Zhi-Qi

    2012-08-01

    Soils, vegetables and rainwaters from three vegetable production bases in the Guiyang area, southwest China, were analyzed for Pb concentrations and isotope compositions to trace its sources in the vegetables and soils. Lead isotopic compositions were not distinguishable between yellow soils and calcareous soils, but distinguishable among sampling sites. The highest (207)Pb/(206)Pb and (208)Pb/(206)Pb ratios were found for rainwaters (0.8547-0.8593 and 2.098-2.109, respectively), and the lowest for soils (0.7173-0.8246 and 1.766-2.048, respectively). The (207)Pb/(206)Pb and (208)Pb/(206)Pb ratios increased in vegetables in the order of rootsmodel for Pb in vegetables. Using deep soils and rainwaters as geogenic and anthropogenic end members in the mixing model, it was estimated that atmospheric Pb contributed 30-77% to total Pb for vegetable roots, 43-71% for stems, 72-85% for leaves, and 90% for capsicum fruits, whereas 10-70% of Pb in all vegetable parts was derived from soils. This research supports that heavy metal contamination in vegetables can result mainly from atmospheric deposition, and Pb isotope technique is useful for tracing the sources of Pb contamination in vegetables. PMID:22705869

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

    PubMed

    Hu, Xiangang; Zhou, Qixing; Luo, Yi

    2010-09-01

    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

  11. Nitrate concentrations in some vegetables and soils in Hamadan, western Iran

    Microsoft Academic Search

    Mohsen Jalali

    2008-01-01

    Excessive use of nitrogen (N) fertilizers contributes to the accumulation of nitrate () in soil and vegetable crops. Vegetables contribute considerably to human intake in Iran. This study was carried out to determine in vegetable crops and soils. Samples of different vegetables (edible portions) were taken from eight fields during spring, summer and autumn. Also samples of two soil depths

  12. Modeling Feedbacks Between Water and Vegetation in the Climate System

    NASA Technical Reports Server (NTRS)

    Miller, James R.; Russell, Gary L.; Hansen, James E. (Technical Monitor)

    2001-01-01

    Not only is water essential for life on earth, but life itself affects the global hydrologic cycle and consequently the climate of the planet. Whether the global feedbacks between life and the hydrologic cycle tend to stabilize the climate system about some equilibrium level is difficult to assess. We use a global climate model to examine how the presence of vegetation can affect the hydrologic cycle in a particular region. A control for the present climate is compared with a model experiment in which the Sahara Desert is replaced by vegetation in the form of trees and shrubs common to the Sahel region. A second model experiment is designed to identify the separate roles of two different effects of vegetation, namely the modified albedo and the presence of roots that can extract moisture from deeper soil layers. The results show that the presence of vegetation leads to increases in precipitation and soil moisture in western Sahara. In eastern Sahara, the changes are less clear. The increase in soil moisture is greater when the desert albedo is replaced by the vegetation albedo than when both the vegetation albedo and roots are added. The effect of roots is to withdraw water from deeper layers during the dry season. One implication of this study is that the insertion of vegetation into the Sahara modifies the hydrologic cycle so that the vegetation is more likely to persist than initially.

  13. Removing vegetation using unsupervised fully constrained least squares linear spectral mixture analysis method in soils surveyed by remote sensing

    NASA Astrophysics Data System (ADS)

    Luo, Hongxia; Ye, Huanzhuo; Ke, Yinghai; Pan, Jianping; Gong, Jianya; Chen, Xiaoling

    2005-01-01

    In the region covered by variable amounts of vegetation, pixel spectra received by remotely-sensed sensor with given spatial resolution are a mixture of soil and vegetation spectra, so vegetation covering on soil influences the accuracy of soils surveying by remote sensing. Mixed pixel spectra are described as a linear combination of endmember signature matrix with appropriate abundance fractions correspond to it in a linear mixture model. According to the principle of this model, abundance fractions of endmembers in every pixel were calculated using unsupervised fully constrained least squares(UFCLS) algorithm. Then the signature of vegetation correspond to its abundance fraction was eliminated, and other endmember signatures covered by vegetation were restituted by scaling their abundance fractions to sum the original pixel total and recalculating the model. After above processing, de-vegetated reflectance images were produced for soils surveying. The accuracies of paddy soils classified using these characteristic images were better than that of using the raw images, but the accuracies of zonal soils were inferior to the latter. Compared to many other image processing methods, such as K-T transformation and ratio bands, the linear spectral unmixing to removing vegetation produced slightly better overall accuracy of soil classification, so it was useful for soils surveying by remote sensing.

  14. Soil erosion-vegetation interactions in Mediterranean-dry reclaimed mining slopes

    NASA Astrophysics Data System (ADS)

    Moreno de las Heras, Mariano; Merino-Martín, Luis; Espigares, Tíscar; Nicolau, José M.

    2014-05-01

    Mining reclamation in Mediterranean-dry environments represents a complex task. Reclaimed mining slopes are particularly vulnerable to the effects of accelerated soil erosion processes, especially when these processes lead to the formation of rill networks. On the other hand, encouraging early vegetation establishment is perceived as indispensable to reduce the risk of degradation in these man-made ecosystems. This study shows a synthesis of soil erosion-vegetation research conducted in reclaimed mining slopes at El Moral field site (Teruel coalfield, central-east Spain). Our results highlight the role of rill erosion processes in the development of reclaimed ecosystems. Runoff routing is conditioned by the development of rill networks, maximizing the loss of water resources at the slope scale by surface runoff and altering the spatial distribution of soil moisture. As a result, the availability of water resources for plant growth is drastically reduced, affecting vegetation development. Conversely, vegetation exerts a strong effect on soil erosion: erosion rates rapidly decrease with vegetation cover and no significant rill erosion is usually observed after a particular cover threshold is reached. These interactive two-way vegetation-soil erosion relationships are further studied using a novel modeling approach that focuses on stability analysis of water-limited reclaimed slopes. Our framework reproduces two main groups of trends along the temporal evolution of reclaimed slopes: successful trends, characterized by widespread vegetation development and the effective control of rill erosion processes; and gullying trends, characterized by the progressive loss of vegetation and a sharp logistic increase in erosion rates. This stability-analysis also facilitates the determination of threshold values for both vegetation cover and rill erosion that drive the long-term reclamation results, assisting the identification of critical situations that require specific human interventions to ensure the long-term sustainability of the restored ecosystems.

  15. 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

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

    2004-01-01

    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

  16. 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)

    Bochet, Esther; García-Fayos, Patricio

    2013-04-01

    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.

  17. [Desorption characteristics of inorganic nitrogen in vegetable garden soil and their effects on soil NO3- -N loss potential].

    PubMed

    Yan, Ming-juan; Zhang, Ming-qing; Chen, Zi-chong; Li, Juan; Lin, Qiong; Wu, Qi-tang; Xiong, De-zhong

    2007-01-01

    With pot experiment and soil nitrogen desorption model, this paper studied the characteristics of nitrogen desorption in vegetable garden soil, and their effects on the NO3- -N concentration of soil leachate. The results showed that soil leachate NO3- -N concentration had a non-linear relationship with the parameters Q, Cli and C1/lamda of soil nitrogen, but the relationship became linear when these eigenvalues were relatively low. A conception of hi-curve cross point was put forward to assess the soil NO3- -N loss potential. When the eigenvalues were higher than the hi-curve cross point X0, the NO3- -N concentration in soil leachate would be increased rapidly in non-linear form, while on the contrary, the increase would be maintained at a lower level. PMID:17396506

  18. Tracking chlordane compositional and chiral profiles in soil and vegetation.

    PubMed

    White, Jason C; Mattina, MaryJane Incorvia; Eitzer, Brian D; Lannucci-Berger, William

    2002-05-01

    The cycling of chlordane and other persistent organic pollutants through the environment must be comprehensively elucidated to assess adequately the human health risks posed from such contaminants. In this study the compositional and chiral profiles of weathered chlordane residues in the soil and vegetative compartments were investigated in order to provide details of the fate and transport of this persistent pesticide. Zucchini was planted in a greenhouse in three bays containing chlordane-contaminated soil. At harvest the vegetation and soil were extracted and analyzed for chlordane content using chiral gas chromatography/ion trap mass spectrometry. Both achiral and chiral chlordane components were quantified. The chlordane concentration in the rhizosphere (soil attached to roots) was significantly less than that in the bulk soil. However, the enantiomeric ratio of the chiral components and overall component ratios had changed little in the rhizosphere relative to the bulk soil. Significant levels of chlordane were detected in the vegetation, the amount varying in different plant tissues from a maximum in roots to a minimum in fruit. In addition to the chlordane concentration gradient in plant tissues, significant shifts in compositional profile, as indicated by the component ratios, and in chiral profile, as indicated by the enantiomeric ratio, of the contaminant were observed in the plant tissues. The data indicate that abiotic processes dominate the transport of the chlordane components through the soil to the plant. This is the first report of the effect of rapid biotic processes within the plant compartment on chlordane compositional and chiral profiles. PMID:12047075

  19. Parameterization of vegetation backscatter in radar-based, soil moisture estimation

    Microsoft Academic Search

    Rajat Bindlish; Ana P Barros

    2001-01-01

    The Integral Equation Model (IEM) was previously used in conjunction with an inversion model to retrieve soil moisture using multifrequency and multipolarization data from Spaceborne Imaging Radar C-band (SIR-C) and X-band Synthetic Aperture Radar (X-SAR). Convergence rates well above 90%, and small RMS errors were attained, for both vegetated and bare soil areas, using radar data collected during Washita 1994.

  20. Assessment of regional biomass-soil relationships using vegetation indexes

    NASA Technical Reports Server (NTRS)

    Lozano-Garcia, D. Fabian; Fernandez, R. Norberto; Johannsen, Chris J.

    1991-01-01

    The development of photosynthetic active biomass in different ecological conditions, as indicated by normalized difference vegetation indices (NDVIs) is compared by performing a stratified sampling (based on soil assocations) on data acquired over Indiana. Data from the NOAA-10 AVHRR were collected for the 1987 and 1988 growing seasons. An NDVI transformation was performed using the two optical bands of the sensor (0.58-0.68 microns and 0.72-1.10 microns). The NDVI is related to the amount of active photosynthetic biomass present on the ground. Samples of NDVI values over 45 fields representing eight soil associations throughout Indiana were collected to assess the effect of soil conditions and acquisition date on the spectral response of the vegetation, as shown by the NDVIs. Statistical analysis of results indicate that land-cover types (forest, forest/pasture, and crops), soil texture, and soil water-holding capacity have an important effect on vegetation biomass changes as measured by AVHRR data. Acquisition dates should be selected with condideration of the phenological stages of vegetation. Sampling of AVHRR data over extended areas should be stratified according to physiographic units rather than man-made boundaries. This will provide more homogeneous samples for statistical analysis.

  1. Estimation of effective hydrologic properties of soils from observations of vegetation density

    NASA Technical Reports Server (NTRS)

    Tellers, T. E.; Eagleson, P. S.

    1980-01-01

    A one-dimensional model of the annual water balance is reviewed. Improvements are made in the method of calculating the bare soil component of evaporation, and in the way surface retention is handled. A natural selection hypothesis, which specifies the equilibrium vegetation density for a given, water limited, climate soil system, is verified through comparisons with observed data. Comparison of CDF's of annual basin yield derived using these soil properties with observed CDF's provides verification of the soil-selection procedure. This method of parameterization of the land surface is useful with global circulation models, enabling them to account for both the nonlinearity in the relationship between soil moisture flux and soil moisture concentration, and the variability of soil properties from place to place over the Earth's surface.

  2. An Intercomparison of Vegetation Products from Satellite-based Observations used for Soil Moisture Retrievals

    NASA Astrophysics Data System (ADS)

    Vreugdenhil, Mariette; de Jeu, Richard; Wagner, Wolfgang; Dorigo, Wouter; Hahn, Sebastian; Bloeschl, Guenter

    2013-04-01

    Vegetation and its water content affect active and passive microwave soil moisture retrievals and need to be taken into account in such retrieval methodologies. This study compares the vegetation parameterisation that is used in the TU-Wien soil moisture retrieval algorithm to other vegetation products, such as the Vegetation Optical Depth (VOD), Net Primary Production (NPP) and Leaf Area Index (LAI). When only considering the retrieval algorithm for active microwaves, which was developed by the TU-Wien, the effect of vegetation on the backscattering coefficient is described by the so-called slope [1]. The slope is the first derivative of the backscattering coefficient in relation to the incidence angle. Soil surface backscatter normally decreases quite rapidly with the incidence angle over bare or sparsely vegetated soils, whereas the contribution of dense vegetation is fairly uniform over a large range of incidence angles. Consequently, the slope becomes less steep with increasing vegetation. Because the slope is a derivate of noisy backscatter measurements, it is characterised by an even higher level of noise. Therefore, it is averaged over several years assuming that the state of the vegetation doesn't change inter-annually. The slope is compared to three dynamic vegetation products over Australia, the VOD, NPP and LAI. The VOD was retrieved from AMSR-E passive microwave data using the VUA-NASA retrieval algorithm and provides information on vegetation with a global coverage of approximately every two days [2]. LAI is defined as half the developed area of photosynthetically active elements of the vegetation per unit horizontal ground area. In this study LAI is used from the Geoland2 products derived from SPOT Vegetation*. The NPP is the net rate at which plants build up carbon through photosynthesis and is a model-based estimate from the BiosEquil model [3, 4]. Results show that VOD and slope correspond reasonably well over vegetated areas, whereas in arid areas, where the microwave signals mostly stem from the soil surface and deeper soil layers, they are negatively correlated. A second comparison of monthly values of both vegetation parameters to modelled NPP data shows that particularly over dry areas the VOD corresponds better to the NPP, with r=0.79 for VOD-NPP and r=-0.09 for slope-NPP. 1. Wagner, W., et al., A Study of Vegetation Cover Effects on ERS Scatterometer Data. IEEE Transactions on Geoscience and Remote Sensing, 1999. 37(2): p. 938-948. 2. Owe, M., R. de Jeu, and J. Walker, A methodology for surface soil moisture and vegetation optical depth retrieval using the microwave polarization difference index. Geoscience and Remote Sensing, IEEE Transactions on, 2001. 39(8): p. 1643-1654. 3. Raupach, M.R., et al., Balances of Water, Carbon, Nitrogen and Phosphorus in Australian Landscapes: (1) Project Description and Results, 2001, Sustainable Minerals Institute, CSIRO Land and Water. 4. Raupach, M.R., et al., Balances of Water, Carbon, Nitrogen and Phosporus in Australian Landscapes: (2) Model Formulation and Testing, 2001, Sustainable Minerals Institute, CSIRO Land and Water. * These products are the joint property of INRA, CNES and VITO under copyright of Geoland2. They are generated from the SPOT VEGETATION data under copyright CNES and distribution by VITO.

  3. Passive Microwave Soil Moisture Downscaling Using Vegetation and Surface Temperatures

    NASA Astrophysics Data System (ADS)

    Fang, B.; Lakshmi, V.

    2012-12-01

    Soil moisture satellite estimates are available from a variety of passive microwave satellite missions, but their resolution is frequently too large for use by land managers and action agencies. In this article, a soil moisture downscaling algorithm based on look-up curves between daily temperature change and daily average soil moisture is presented and developed to bridge the scale. The algorithm was derived from 1/8o spatial resolution North American Land Data Assimilation System (NLDAS-2) surface temperature and soil moisture data, and also used 5 km Advanced Very High Resolution Radiometer (AVHRR) and 1km Moderate Resolution Imaging Spectroradiometer (MODIS) Normalized Difference Vegetation Index (NDVI) as look-up dataset for different vegetation and surface temperature conditions. The differences between 1km MODIS temperature downscaled soil moisture values and Advanced Microwave Scanning Radiometer - EOS (AMSR-E) soil moisture values were used to modify AMSR-E soil moistures. The 1km downscaled soil moisture maps display greater details on the spatial pattern of soil moisture distribution. Two sets of ground-based measurements, the Oklahoma Mesonet and the Little Washita Micronet were used to validate the algorithm. The Root Mean Square Error (RMSE) of the 1km downscaled soil moisture versus Oklahoma Mesonet observations for clear days ranges from 0.119~0.168, whereas the RMSE of 1km downscaled soil moisture versus the Little Washita Watershed observations ranges from 0.022~0.077. The results demonstrate that the 1 km downscaled soil moisture has better agreement with watershed in situ data compared to the other sources of soil moisture.

  4. Sigma Mesa: Background elemental concentrations in soil and vegetation, 1979

    SciTech Connect

    Ferenbaugh, R.W.; Gladney, E.S.; Brooks, G.H. Jr.

    1990-10-01

    In 1979, soil and vegetation samples were collected on Sigma Mesa to provide background data before construction on the mesa. Elemental data are presented for soil, grass, juniper, pinon pine, and oak. None of the data looks out of the ordinary. The purpose of the sampling program was to acquire, before any disturbance, a set of data to be used as background for future impact analysis. 6 refs., 2 figs., 7 tabs.

  5. Effect of a coupled soil water–plant gas exchange on forest energy fluxes: Simulations with the coupled vegetation–boundary layer model HIRVAC

    Microsoft Academic Search

    Björn Fischer; Valeri Goldberg; Christian Bernhofer

    2008-01-01

    Long-living plant communities such as forests reduce their transpiration by closing and opening the leaf stomata as a common strategy to save water in dry periods. Meteorological models including vegetation should consider this mechanism to simulate realistic water transport from the plant to the atmosphere. Results of the German network project VERTIKO showed that commonly used meso-models such as Lokalmodell

  6. Soil Moisture and Vegetation Effects on GPS Reflectivity From Land

    NASA Astrophysics Data System (ADS)

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

    2004-12-01

    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.

  7. Vegetation on the Soil Infiltration System Treating Livestock Wastewater

    NASA Astrophysics Data System (ADS)

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

    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.

  8. Evolution of hydrological pathways in engineered hillslopes due to soil and vegetation development

    NASA Astrophysics Data System (ADS)

    Appels, Willemijn M.; Ireson, Andrew M.; McDonnell, Jeffrey J.; Barbour, S. Lee

    2015-04-01

    The structure and hydraulic properties of soils and bedrock within a hillslope combined with the timing and rates of water availability control the partitioning of precipitation into vertical and lateral flowpaths. In natural hillslope sites, heterogeneity in both soil texture and structure are the result of long-term landscape evolution processes and consequently can be assumed to be static relative to the timescale of rainfall-runoff processes. However; engineered hillslopes, constructed commonly as reclamation covers overlying mine waste, have been observed to undergo rapid changes in hydraulic properties over relatively short timescales (i.e. 3-5 years) as a result of weathering (e.g. freeze-thaw and wet-dry cycles) and vegetation growth (e.g. increasing rooting depth and density). Rainfall-runoff responses on such hillslopes would therefore not only be expected to reflect seasonal dynamics, but also the evolution of the system from a relatively homogeneous initial condition to a system with increasing heterogeneity of soil texture and structure. We present results of a combined field and modeling study of three prototype soil covers on a saline-sodic shale overburden dump at the Syncrude Canada Ltd. Mildred Lake mine, north of Fort McMurray, Canada. Since their construction in 1999, soil properties, hydrological response to atmospheric and vegetative demands, and vegetation properties have been extensively monitored. The three covers have undergone substantial evolution due to freeze-thaw processes and aggrading vegetation. In this work, we quantify hydrological processes in the reclamation covers, focusing on inter- and intra-annual patterns. To this purpose we analyzed the long-term hydrometric data with field sampling of the distribution of salts and the stable isotopes of water within soil water and subsurface flow in the base of the cover. We use a 2D Hydrus model to explore the co-evolution of soil and vegetation and quantify its effect on flow partitioning and salt movement from the overburden into the soil.

  9. Mapping Vegetation, Soils, and Geology in Semiarid Shrublands Using Spectral Matching and Mixture Modeling of SWIR AVIRIS Imagery

    Microsoft Academic Search

    Nick A. Drake; Steve Mackin; Jeff J. Settle

    1999-01-01

    Spectral matching and linear mixture modeling techniques have been applied to synthetic imagery and AVIRIS SWIR imagery of a semiarid rangeland in order to determine their effectiveness as mapping tools, the synergism between the two methods, and their advantages, and limitations for rangeland resource exploitation and management. Spectral matching of pure library spectra was found to be an effective method

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

    Microsoft Academic Search

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

    2008-01-01

    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

  11. Sulfamethazine sorption to vegetative filter strip and row crop soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Veterinary antibiotic (VA) presence in the environment, often associated with land application of manure, has generated significant interest in VA fate and transport in soil. However, few studies have focused on land management practices, such as vegetative filter strips, that might mitigate VA loss...

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

    NASA Astrophysics Data System (ADS)

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

    2005-12-01

    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.

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

    Microsoft Academic Search

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

    2011-01-01

    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

  14. Vegetation and Roughness Controls on Field Scale Soil Moisture Variability

    NASA Astrophysics Data System (ADS)

    Adams, J. R.; Berg, A. A.; Toth, B.; Magagi, R.

    2009-05-01

    Downscaling of satellite-based passive microwave soil moisture products such as those to be derived from the Soil Moisture and Ocean Salinity (SMOS) mission requires enhanced understanding of controls of field scale soil moisture variability. A RADARSAT 2 field validation campaign was conducted in July 2008 to measure soil conditions, crop parameters and surface roughness over a six day period, at a network of 10 agricultural sites in Saskatchewan (N 50° - N 51°; W 105° - W 106°). Four crop types are analysed: pulse crops, cereals, oilseeds, and fallow fields, with a sample area of 2.1 km2 per site. From this data set we evaluate the impact of vegetation type and surface roughness on field scale soil moisture variability using parametric and non-parametric statistical approaches. Our results demonstrate the importance of both field scale roughness and vegetation type on field scale variability. Of significance, field scale roughness can be measured from satellite platforms such as RADARSAT-2 and vegetation type is available from optical sensors.

  15. Extraction of soil and vegetation parameters from high resolution bi-directional reflectance spectra

    NASA Technical Reports Server (NTRS)

    Huete, A. R.

    1992-01-01

    High spectral resolution reflectance spectra were collected over a semi-desert grassland at both dry and wet season periods. Spectral reflectance measurements were made from several viewing angles at both low and high solar zenith angles. A mixture model was used to separate and extract green vegetation from dry/dead vegetation and soil. The extracted vegetation signal varied greatly with view and sun angle variations such that off-nadir viewing and illuminating angles resulted in the highest vegetation loadings. These variations were normalized with cosine functions for both sun and view angle. These results offer a methodology for standardizing multi-temporal and multi-angular satellite measurements of vegetation activity.

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

    NASA Astrophysics Data System (ADS)

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

    2006-08-01

    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.

  17. Optimal configurations of bistatic radar for retrieving soil moisture and vegetation biomass

    Microsoft Academic Search

    N. Pierdicca; L. Pulvirenti; L. Guerriero; G. Della Pietra

    2007-01-01

    The possible contribution of bistatic radar measurements to estimate bare soil moisture and vegetation biomass is investigated by a simulation study based on well established electromagnetic models (both coherent and incoherent components). The best system configuration, in terms of observation directions, polarisations and frequency has been singled out by predicting the retrieval accuracy. This has been evaluated using the Cramer-Rao

  18. Mercury concentrations in oligohaline wetland vegetation and associated soil biogeochemistry.

    PubMed

    Willis, Jonathan M; Gambrell, Robert P; Hester, Mark W

    2011-10-01

    Concentrations of mercury were determined in above- and below-ground tissues of dominant plant species, as well as soils, in the wetlands of Lake Maurepas, Louisiana. Indicators of wetland soil biogeochemical status, such as soil redox potential, pore-water nutrient concentrations, and pore-water total sulfides, were also determined. Total mercury concentrations in plant tissues were within the typical range for vegetation not exposed to mercury contamination. Similarly, total mercury concentrations in soils were typical of uncontaminated wetlands within this geographic region. Soil methyl mercury levels in this study are slightly lower than those reported in other studies of nearby wetlands. This may reflect the less extensive geographic sampling in this study, or the low water levels in the Lake Maurepas system immediately prior to and during this study, which would have altered soil biogeochemical status. This is corroborated by measurements of soil redox potential and soil pore-water nitrogen and sulfur constituents conducted during this study that suggest minimal sulfate reduction was occurring in surficial soils. This study indicates that the wetlands surrounding Lake Maurepas are typical of many uncontaminated oligohaline wetlands in the southeastern U.S. in regard to mercury concentrations. PMID:21188507

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

    NASA Astrophysics Data System (ADS)

    Runyan, C.; D'Odorico, P.

    2010-12-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    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.

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

    PubMed

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

    2007-05-25

    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

  2. Modelling the Congo basin ecosystems with a dynamic vegetation model

    NASA Astrophysics Data System (ADS)

    Dury, Marie; Hambuckers, Alain; Trolliet, Franck; Huynen, Marie-Claude; Haineaux, Damien; Fontaine, Corentin M.; Fayolle, Adeline; François, Louis

    2014-05-01

    The scarcity of field observations in some parts of the world makes difficult a deep understanding of some ecosystems such as humid tropical forests in Central Africa. Therefore, modelling tools are interesting alternatives to study those regions even if the lack of data often prevents sharp calibration and validation of the model projections. Dynamic vegetation models (DVMs) are process-based models that simulate shifts in potential vegetation and its associated biogeochemical and hydrological cycles in response to climate. Initially run at the global scale, DVMs can be run at any spatial scale provided that climate and soil data are available. In the framework of the BIOSERF project ("Sustainability of tropical forest biodiversity and services under climate and human pressure"), we use and adapt the CARAIB dynamic vegetation model (Dury et al., iForest - Biogeosciences and Forestry, 4:82-99, 2011) to study the Congo basin vegetation dynamics. The field campaigns have notably allowed the refinement of the vegetation representation from plant functional types (PFTs) to individual species through the collection of parameters such as the specific leaf area or the leaf C:N ratio of common tropical tree species and the location of their present-day occurrences from literature and available database. Here, we test the model ability to reproduce the present spatial and temporal variations of carbon stocks (e.g. biomass, soil carbon) and fluxes (e.g. gross and net primary productivities (GPP and NPP), net ecosystem production (NEP)) as well as the observed distribution of the studied species over the Congo basin. In the lack of abundant and long-term measurements, we compare model results with time series of remote sensing products (e.g. vegetation leaf area index (LAI), GPP and NPP). Several sensitivity tests are presented: we assess consecutively the impacts of the level at which the vegetation is simulated (PFTs or species), the spatial resolution and the initial land cover (potential or human-induced). First, we show simulations over the whole Congo basin at a 0.5° spatial resolution. Then, we present high-resolution simulations (1 km) carried out over different areas of the Congo basin, notably the DRC part of the WWF Lake Tele - Lake Tumba Landscape. Studied in the BIOSERF project, this area is characterized by a forest-savannah mosaic but also by swamp and flooded forest. In addition, forward transient projections of the model driven with the outputs of about thirty global climate models (GCMs) from the new Coupled Model Intercomparison Project Phase 5 (CMIP5) will permit to outline the likely response of carbon pools to changing climate over the Congo basin during the 21th century.

  3. The effects of vegetation cover on the radar and radiometric sensitivity to soil moisture

    NASA Technical Reports Server (NTRS)

    Ulaby, F. T.; Dobson, M. C.; Brunfeldt, D. R.; Razani, M.

    1982-01-01

    The measured effects of vegetation canopies on radar and radiometric sensitivity to soil moisture are compared to emission and scattering models. The models are found to predict accurately the measured emission and backscattering for various crop canopies at frequencies between 1.4 and 5.0 GHz, especially at theta equal to or less than 30 deg. Vegetation loss factors, L(theta), increase with frequency and are found to be dependent upon canopy type and water content. In addition, the radiometric power absorption coefficient of a mature corn canopy is 1.75 times that calculated for the radar. Comparison of an L-band radiometer with a C-band radar shows the two systems to be complementary in terms of accurate soil moisture sensing over the extreme range of naturally occurring soil moisture conditions.

  4. Fungal communities in soils along a vegetative ecotone.

    PubMed

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

    2013-01-01

    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

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

    NASA Astrophysics Data System (ADS)

    Gu, Yingxin; Hunt, Eric; Wardlow, Brian; Basara, Jeffrey B.; Brown, Jesslyn F.; Verdin, James P.

    2008-11-01

    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).

  6. Decadal predictability of soil water, vegetation, and wildfire frequency over North America

    NASA Astrophysics Data System (ADS)

    Chikamoto, Yoshimitsu; Timmermann, Axel; Stevenson, Samantha; DiNezio, Pedro; Langford, Sally

    2015-01-01

    The potential decadal predictability of land hydrological and biogeochemical variables in North America is examined using a 900-year-long pre-industrial control simulation, conducted with the NCAR Community Earth System Model (CESM) version 1.0.3. The leading modes of simulated North American precipitation and soil water storage are characterized essentially by qualitatively similar meridional seesaw patterns associated with the activity of the westerly jet. Whereas the corresponding precipitation variability can be described as a white noise stochastic process, power spectra of vertically integrated soil water exhibit significant redness on timescales of years to decades, since the predictability of soil water storage arises mostly from the integration of precipitation variability. As a result, damped persistence hindcasts following a 1st order Markov process are skillful with lead times of up to several years. This potential multi-year skill estimate is consistent with ensemble hindcasts conducted with the CESM for various initial conditions. Our control simulation further suggests that decadal variations in soil water storage also affect vegetation and wildfire occurrences. The long-term potential predictability of soil water variations in combination with the slow regrowth of vegetation after major disruptions leads to enhanced predictability on decadal timescales for vegetation, terrestrial carbon stock, and fire frequency, in particular in the Southern United States (US)/Mexico region. By contrast, the prediction skill of fire frequency in the Northern US is limited to 1 year. Our results demonstrate that skillful decadal predictions of soil water storage, carbon stock, and fire frequency are feasible with proper initialization of soil conditions. Although the potential predictability in our idealized modeling framework would overestimate the real predictability of the coupled climate-land-vegetation system, the decadal climate prediction may become beneficial for water resource management, forestry, and agriculture.

  7. Prairie vegetation and soil nutrient responses to ungulate carcasses

    Microsoft Academic Search

    E. Gene Towne

    2000-01-01

    The impact of large ungulate carcasses on grassland dynamics was investigated by monitoring vegetation and soil nutrients\\u000a in 50-cm circular zones around the center of bison (Bos bison), cattle (B. taurus), and deer (Odocoileus virginianus) carcasses. An ungulate carcass creates an intense localized disturbance that varies with animal size and the season of death.\\u000a Unlike other natural disturbances, carcasses deposit

  8. Complex vegetation responses to soil disturbances in mountain grassland

    Microsoft Academic Search

    Maria-Teresa Sebastià; Laura Puig

    2008-01-01

    We studied vegetation responses to disturbances originated by ants and voles in subalpine grasslands in the Eastern Pyrenees.\\u000a We compared the effects of these small-scale disturbances with those of a large-scale disturbance caused by ploughing. We\\u000a wanted to know if these soil disturbances promoted species richness through the existence of a specific guild of plants colonizing\\u000a these areas, and if

  9. Experimental evaluation of mercury release from flooded vegetation and soils

    Microsoft Academic Search

    K. A. Morrison; N. Thérien

    1991-01-01

    Significant increases in Hg concentrations have been noted in fish caught in newly-created hydroelectric reservoirs in various\\u000a parts of northern Canada. It has been hypothesized that a significant contributing factor to these increased levels may be\\u000a the release to the water column of Hg from flooded vegetation and soils and subsequent methylation by bacteria whose growth\\u000a has been stimulated by

  10. Soil TPH Concentration Estimation Using Vegetation Indices in an Oil Polluted Area of Eastern China

    PubMed Central

    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.

    2013-01-01

    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 (R2?=?0.73) and accuracy of prediction (RMSE?=?104.2 mg kg?1). For other vegetation indices and red edge parameters, the R2 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 (R2?=?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

  11. The Role of Vegetation and Mulch in Mitigating the Impact of Raindrops on Soils in Urban Vegetated Green Infrastructure Systems

    NASA Astrophysics Data System (ADS)

    Alizadehtazi, B.; Montalto, F. A.; Sjoblom, K.

    2014-12-01

    Raindrop impulses applied to soils can break up larger soil aggregates into smaller particles, dispersing them from their original position. The displaced particles can self-stratify, with finer particles at the top forming a crust. Occurrence of this phenomenon reduces the infiltration rate and increases runoff, contributing to downstream flooding, soil erosion, and non point source pollutant loads. Unprotected soil surfaces (e.g. without vegetation canopies, mulch, or other materials), are more susceptible to crust formation due to the higher kinetic energy associated with raindrop impact. By contrast, soil that is protected by vegetation canopies and mulch layers is less susceptible to crust formation, since these surfaces intercept raindrops, dissipating some of their kinetic energy prior to their impact with the soil. Within this context, this presentation presents preliminary laboratory work conducted using a rainfall simulator to determine the ability of new urban vegetation and mulch to minimize soil crust formation. Three different scenarios are compared: a) bare soil, b) soil with mulch cover, and c) soil protected by vegetation canopies. Soil moisture, surface penetration resistance, and physical measurements of the volume of infiltrate and runoff are made on all three surface treatments after simulated rainfall events. The results are used to develop recommendations regarding surface treatment in green infrastructure (GI) system designs, namely whether heavily vegetated GI facilities require mulching to maintain infiltration capacity.

  12. Environmental sensor networks for vegetation, animal and soil sciences

    NASA Astrophysics Data System (ADS)

    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

    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.

  13. Canopy reflectance modelling of semiarid vegetation

    NASA Technical Reports Server (NTRS)

    Franklin, Janet

    1994-01-01

    Three different types of remote sensing algorithms for estimating vegetation amount and other land surface biophysical parameters were tested for semiarid environments. These included statistical linear models, the Li-Strahler geometric-optical canopy model, and linear spectral mixture analysis. The two study areas were the National Science Foundation's Jornada Long Term Ecological Research site near Las Cruces, NM, in the northern Chihuahuan desert, and the HAPEX-Sahel site near Niamey, Niger, in West Africa, comprising semiarid rangeland and subtropical crop land. The statistical approach (simple and multiple regression) resulted in high correlations between SPOT satellite spectral reflectance and shrub and grass cover, although these correlations varied with the spatial scale of aggregation of the measurements. The Li-Strahler model produced estimated of shrub size and density for both study sites with large standard errors. In the Jornada, the estimates were accurate enough to be useful for characterizing structural differences among three shrub strata. In Niger, the range of shrub cover and size in short-fallow shrublands is so low that the necessity of spatially distributed estimation of shrub size and density is questionable. Spectral mixture analysis of multiscale, multitemporal, multispectral radiometer data and imagery for Niger showed a positive relationship between fractions of spectral endmembers and surface parameters of interest including soil cover, vegetation cover, and leaf area index.

  14. Soil-vegetation-climate interactions in arid landscapes: Effects of the North American monsoon on grass recruitment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We used a daily time step, multi-layer simulation model of soil water dynamics to integrate effects of soils, vegetation, and climate on the recruitment of Bouteloua eriopoda (black grama), the historically dominant grass in the Chihuahuan Desert. We simulated landscapes at the Jornada ARS-LTER site...

  15. Environmental behavior of technetium in soil and vegetation: implications for radiological impact assessment

    SciTech Connect

    Hoffman, F.O.

    1982-04-01

    Significant radiological exposures have been estimated for hypothetical atmospheric releases of Tc-99 from gaseous diffusion facilities when vegetation-to-soil concentration ratios representative of laboratory experiments are substituted for generic default values assumed in current regulatory models. To test the relevancy of these laboratory ratios, field investigations were conducted to obtain measurements of the vegetation-to-soil concentration ratio for Tc-99 in samples collected near operating gaseous diffusion facilities and to observe the dynamic behavior of technetium in soil and vegetation following a single application of a sprayed solution of /sup 95m/TcO/sub 4//sup -/ Comparison of observed field concentration ratios and calculated steady-state concentration ratios with ratios obtained from previous laboratory experiments indicates that concentration ratios obtained from field data are one to two orders of magnitude less than those obtained from the laboratory. Furthermore, a substantial accumulation of technetium in soil and vegetation may not occur over long periods of time, since concentrations of technetium in both environmental media were observed to decrease with time subsequent to initial application of /sup 95m/TcO/sub 4//sup -/.

  16. Numerical simulations of the effect of soil moisture and vegetation cover on the development of deep convection

    SciTech Connect

    Clark, C.A.; Arritt, R.W. [Iowa State Univ., Ames, IA (United States)] [Iowa State Univ., Ames, IA (United States)

    1995-09-01

    A one-dimensional (column) version of a primitive equations model has been used to study the impact of soil moisture and vegetation cover on the development of deep cumulus convection in the absence of dynamical forcing. The model includes parameterizations of radiation, turbulent exchange, deep convection, shallow boundary layer convective clouds, vegetation, and soil temperature and moisture. Multiple one-dimensional experiments were performed using the average July sounding for Topeka, Kansas, as the initial condition. A range of volumetric soil moisture from one-half of the wilting point to saturation and vegetation cover ranging from bare soil to full cover were considered. Vegetation cover was found to promote convection, both by extraction of soil moisture and by shading the soil so that conduction of heat into the soil was reduced (thereby increasing the available energy). The larger values of initial soil moisture were found to delay the onset of precipitation and to increase the precipitation amount. The greatest rainfall amounts were generally predicted to occur for moist, fully vegetated surfaces. Vegetation cover also had a pronounced moderating influence, decreasing the sensitivity of the results to the soil moisture content. The general nature of the results prevailed for modest variations in the initial summertime atmospheric profile and changes in the details of the surface parameterization. The inclusion of shading by shallow cumulus clouds tended to reduce the convection for moist, bare (or partly bare) soil. The nonlinearity of the interaction between the land surface and convective precipitation implies that the effects of subgrid landscape heterogeneity in climate models cannot accurately be represented by linear averages of the contributions from the different surface types. 53 refs., 15 figs., 2 tabs.

  17. Numerical Simulations of the Effect of Soil Moisture and Vegetation Cover on the Development of Deep Convection.

    NASA Astrophysics Data System (ADS)

    Clark, Craig A.; Arritt, Paymond W.

    1995-09-01

    A one-dimensional (column) version of a primitive equations model has been used to study the impact of soil moisture and vegetation cover on the development of deep cumulus convection in the absence of dynamical forcing. The model includes parameterizations of radiation, turbulent exchange, deep convection, shallow boundary layer convective clouds, vegetation, and soil temperature and moisture. Multiple one-dimensional experiments were performed using the average July sounding for Topeka, Kansas, as the initial condition. A range of volumetric soil moisture from one-half of the wilting point to saturation and vegetation cover ranging from bare soil to full cover were considered.Vegetation cover was found to promote convection, both by extraction of soil moisture and by shading the soil so that conduction of heat into the soil was reduced (thereby increasing the available energy). The larger values of initial soil moisture were found to delay the onset of precipitation and to increase the precipitation amount. The greatest rainfall amounts were generally predicted to occur for moist, fully vegetated surfaces. Vegetation cover also had a pronounced moderating influence, decreasing the sensitivity of the results to the soil moisture content. The general nature of the results prevailed for modest variations in the initial summertime atmospheric profile and changes in the details of the surface parameterization. The inclusion of shading by shallow cumulus clouds tended to reduce the convection for moist, bare (or partly bare) soil. The nonlinearity of the interaction between the land surface and convective precipitation implies that the effects of subgrid landscape heterogeneity in climate models cannot accurately be represented by linear averages of the contributions from the different surface types.

  18. Soil moisture status estimation over Three Gorges area with Landsat TM data based on temperature vegetation dryness index

    NASA Astrophysics Data System (ADS)

    Xu, Lina; Niu, Ruiqing; Li, Jiong; Dong, Yanfang

    2011-12-01

    Soil moisture is the important indicator of climate, hydrology, ecology, agriculture and other parameters of the land surface and atmospheric interface. Soil moisture plays an important role on the water and energy exchange at the land surface/atmosphere interface. Remote sensing can provide information on large area quickly and easily, so it is significant to do research on how to monitor soil moisture by remote sensing. This paper presents a method to assess soil moisture status using Landsat TM data over Three Gorges area in China based on TVDI. The potential of Temperature- Vegetation Dryness Index (TVDI) from Landsat TM data in assessing soil moisture was investigated in this region. After retrieving land surface temperature and vegetation index a TVDI model based on the features of Ts-NDVI space is established. And finally, soil moisture status is estimated according to TVDI. It shows that TVDI has the advantages of stability and high accuracy to estimating the soil moisture status.

  19. Modelling the effects of atmospheric C0 2 on vegetation-atmosphere interactions

    Microsoft Academic Search

    Andrew D. Friend; Peter M. Cox

    1995-01-01

    The effect of doubling atmospheric CO2 concentration (Ca) on climate and vegetation is investigated using a combined climate-vegetation model. The vegetation model predicts the response of leaf area index, canopy transpiration (ET) and whole-plant carbon balance to changes in climate, soil moisture, and atmospheric CO2 forcing. This model has been embedded in the UK Meteorological Office Single Column Model (SCM),

  20. NITRATE MOVEMENT IN SOUTHEASTERN COASTAL PLAIN SOILS UNDER CONSERVATION-TILLED VEGETABLE PRODUCTION

    E-print Network

    Decoteau, Dennis R.

    NITRATE MOVEMENT IN SOUTHEASTERN COASTAL PLAIN SOILS UNDER CONSERVATION-TILLED VEGETABLE PRODUCTION before and after vegetable crop production over a four year period. This publication reports soil nitrate G.D. Hoyt1 , D.C. Sanders2 , J.T. D.R. Decoteau3 , ABSTRACT Movement of soil nitrates by leaching

  1. Soil phosphorus landscape models for precision soil conservation.

    PubMed

    Hong, Jinseok; Grunwald, Sabine; Vasques, Gustavo M

    2015-05-01

    Phosphorus (P) enrichment in soils has been documented in the Santa Fe River watershed (SFRW, 3585 km) in north-central Florida. Yet the environmental factors that control P distribution in soils across the landscape, with potential contribution to water quality impairment, are not well understood. The main goal of this study was to develop soil-landscape P models to support a "precision soil conservation" approach combining fine-scale (i.e., site-specific) and coarse-scale (i.e., watershed-extent) assessment of soil P. The specific objectives were to: (i) identify those environmental properties that impart the most control on the spatial distribution of soil Mehlich-1 extracted P (MP) in the SFRW; (ii) model the spatial patterns of soil MP using geostatistical methods; and (iii) assess model quality using independent validation samples. Soil MP data at 137 sites were fused with spatially explicit environmental covariates to develop soil MP prediction models using univariate (lognormal kriging, LNK) and multivariate methods (regression kriging, RK, and cokriging, CK). Incorporation of exhaustive environmental data into multivariate models (RK and CK) improved the prediction of soil MP in the SFRW compared with the univariate model (LNK), which relies solely on soil measurements. Among all tested environmental covariates, land use and vegetation related properties (topsoil) and geologic data (subsoil) showed the largest predictive power to build inferential models for soil MP. Findings from this study contribute to a better understanding of spatially explicit interactions between soil P and other environmental variables, facilitating improved land resource management while minimizing adverse risks to the environment. PMID:26024255

  2. Use of LANDSAT images of vegetation cover to estimate effective hydraulic properties of soils

    NASA Technical Reports Server (NTRS)

    Eagleson, Peter S.; Jasinski, Michael F.

    1988-01-01

    The estimation of the spatially variable surface moisture and heat fluxes of natural, semivegetated landscapes is difficult due to the highly random nature of the vegetation (e.g., plant species, density, and stress) and the soil (e.g., moisture content, and soil hydraulic conductivity). The solution to that problem lies, in part, in the use of satellite remotely sensed data, and in the preparation of those data in terms of the physical properties of the plant and soil. The work was focused on the development and testing of a stochastic geometric canopy-soil reflectance model, which can be applied to the physically-based interpretation of LANDSAT images. The model conceptualizes the landscape as a stochastic surface with bulk plant and soil reflective properties. The model is particularly suited for regional scale investigations where the quantification of the bulk landscape properties, such as fractional vegetation cover, is important on a pixel by pixel basis. A summary of the theoretical analysis and the preliminary testing of the model with actual aerial radiometric data is provided.

  3. Climate, vegetation, and soil controls on hydraulic redistribution in shallow tree roots

    NASA Astrophysics Data System (ADS)

    Yu, Kailiang; D'Odorico, Paolo

    2014-04-01

    Hydraulic redistribution defined as the translocation of soil moisture by plant root systems in response to water potential gradients is a phenomenon widely documented in different climate, vegetation, and soil conditions. Past research has largely focused on hydraulic redistribution in deep tree roots with access to groundwater and/or winter rainfall, while the case of relatively shallow (i.e., ?1-2 m deep) tree roots has remained poorly investigated. In fact, it is not clear how hydraulic redistribution in shallow root zones is affected by climate, vegetation, and soil properties. In this study, we developed a model to investigate the climate, vegetation, and soil controls on the net direction and magnitude of hydraulic redistribution in shallow tree root systems at the growing season to yearly timescale. We used the model to evaluate the effect of hydraulic redistribution on the water stress of trees and grasses. We found that hydraulic lift increases with decreasing rainfall frequency, depth of the rooting zone, root density in the deep soil and tree leaf area index; at the same time for a given rainfall frequency, hydraulic lift increases with increasing average rainstorm depth and soil hydraulic conductivity. We propose that water drainage into deeper soil layers can lead to the emergence of vertical water potential gradients sufficient to explain the occurrence of hydraulic lift in shallow tree roots without invoking the presence of a shallow water table or winter precipitation. We also found that hydraulic descent reduces the water stress of trees and hydraulic lift reduces the water stress of grass with important implications on tree-grass interactions.

  4. Development of a deterministic downscaling algorithm for remote sensing soil moisture footprint using soil and vegetation classifications

    NASA Astrophysics Data System (ADS)

    Shin, Yongchul; Mohanty, Binayak P.

    2013-10-01

    Soil moisture (SM) at the local scale is required to account for small-scale spatial heterogeneity of land surface because many hydrological processes manifest at scales ranging from cm to km. Although remote sensing (RS) platforms provide large-scale soil moisture dynamics, scale discrepancy between observation scale (e.g., approximately several kilometers) and modeling scale (e.g., few hundred meters) leads to uncertainties in the performance of land surface hydrologic models. To overcome this drawback, we developed a new deterministic downscaling algorithm (DDA) for estimating fine-scale soil moisture with pixel-based RS soil moisture and evapotranspiration (ET) products using a genetic algorithm. This approach was evaluated under various synthetic and field experiments (Little Washita-LW 13 and 21, Oklahoma) conditions including homogeneous and heterogeneous land surface conditions composed of different soil textures and vegetations. Our algorithm is based on determining effective soil hydraulic properties for different subpixels within a RS pixel and estimating the long-term soil moisture dynamics of individual subpixels using the hydrological model with the extracted soil hydraulic parameters. The soil moisture dynamics of subpixels from synthetic experiments matched well with the observations under heterogeneous land surface condition, although uncertainties (Mean Bias Error, MBE: -0.073 to -0.049) exist. Field experiments have typically more variations due to weather conditions, measurement errors, unknown bottom boundary conditions, and scale discrepancy between remote sensing pixel and model grid resolution. However, the soil moisture estimates of individual subpixels (from the airborne Electronically Scanned Thinned Array Radiometer (ESTAR) footprints of 800 m × 800 m) downscaled by this approach matched well (R: 0.724 to -0.914, MBE: -0.203 to -0.169 for the LW 13; R: 0.343-0.865, MBE: -0.165 to -0.122 for the LW 21) with the in situ local scale soil moisture measurements during Southern Great Plains Experiment 1997 (SGP97). The good correspondence of observed soil water characteristics ?(h) functions (from the soil core samples) and genetic algorithm (GA) searched soil parameters at the LW 13 and 21 sites demonstrated the robustness of the algorithm. Although the algorithm is tested under limited conditions at field scale, this approach improves the availability of remotely sensed soil moisture product at finer resolution for various land surface and hydrological model applications.

  5. Vegetation stress from soil moisture and chlorophyll fluorescence: synergy between SMAP and FLEX approaches

    NASA Astrophysics Data System (ADS)

    Moreno, Jose; Moran, Susan

    2014-05-01

    Vegetation stress detection continues being a focal objective for remote sensing techniques. It has implications not only for practical applications such as irrigation optimization or precision agriculture, but also for global climate models, providing data to better link water and carbon exchanges between the surface and the atmospheric and improved parameterization of the role of terrestrial vegetation in the coupling of water and carbon cycles. Traditional approaches to map vegetation stress using remote sensing techniques have been based on measurements of soil moisture status, canopy (radiometric) temperature and, to a lesser extent, canopy water content, but new techniques such as the dynamics of vegetation fluorescence emission, are also now available. Within the context of the preparatory activities for the SMAP and FLEX missions, a number of initiatives have been put in place to combine modelling activities and field experiments in order to look for alternative and more efficient ways of detecting vegetation stress, with emphasis on synergistic remote sensing approaches. The potential of solar-induced vegetation fluorescence as an early indicator of stress has been widely demonstrated, for different type of stress conditions: light amount (excess illumination) and conditions (direct/diffuse), temperature extremes (low and high), soil water availability (soil moisture), soil nutrients (nitrogen), atmospheric water vapour and atmospheric CO2 concentration. The effects caused by different stress conditions are sometimes difficult to be decoupled, also because different causes are often combined, but in general they then to change the overall fluorescence emission (modulating amplitude) or changing the relative contributions of photosystems PSI and PSII or the relative fluorescence re-absorption effects caused by modifications in the structure of pigment bed responsible for light absorption, in particular for acclimation for persistent stress conditions. While soil moisture deficit is often the reason for the stress, the capability for an early detection of short-time stress conditions is one of the main advantages of vegetation fluorescence. The combined usage of active and passive techniques is also discussed. In the case of soil moisture, combination of active (radar) and passive (L-band radiometry) approaches are used, while in the case of fluorescence active (laser induced) and passive (solar induced) techniques are used as well. Experience from active techniques in laboratory and field conditions helps the operational usage of passive techniques which are readily applicable to satellite observations. Vegetation fluorescence dynamics, particularly over boreal forest, is characterized by an abrupt change in fluorescence levels in coincidence with the activation and deactivation of the photosynthetic machinery at start/end of growing season, which is also related to freeze/thaw state of soil conditions. The interest of looking at such transitions both on the side of photosynthetic activity (combined fluorescence and temperature measurements) and freeze/thaw conditions (L-band radiometry) can provide an unprecedented description of the soil and vegetation interactions and dynamical feedbacks in the energy and chemical exchanges with the atmosphere. A review of methods and results will be discussed in this paper, including suggestions for synergistic approaches to be exploited in future research priorities in vegetation stress detection.

  6. Responses of soil microbial and nematode communities to aluminum toxicity in vegetated oil-shale-waste lands

    E-print Network

    Neher, Deborah A.

    Responses of soil microbial and nematode communities to aluminum toxicity in vegetated oil community structure and soil aluminum (Al) content in different vegetated aluminum-rich ecosystems. Our. The concentration of water- soluble Al was normally greater in vegetated than non- vegetated soil. The residual Al

  7. Bacterial and enchytraeid abundance accelerate soil carbon turnover along a lowland vegetation gradient in interior Alaska

    USGS Publications Warehouse

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

    2012-01-01

    Boreal wetlands are characterized by a mosaic of plant communities, including forests, shrublands, grasslands, and fens, which are structured largely by changes in topography and water table position. The soil associated with these plant communities contain quantitatively and qualitatively different forms of soil organic matter (SOM) and nutrient availability that drive changes in biogeochemical cycling rates. Therefore different boreal plant communities likely contain different soil biotic communities which in turn affect rates of organic matter decomposition. We examined relationships between plant communities, microbial communities, enchytraeids, and soil C turnover in near-surface soils along a shallow topographic soil moisture and vegetation gradient in interior Alaska. We tested the hypothesis that as soil moisture increases along the gradient, surface soils would become increasingly dominated by bacteria and mesofauna and have more rapid rates of C turnover. We utilized bomb radiocarbon techniques to infer rates of C turnover and the 13C isotopic composition of SOM and respired CO2 to infer the degree of soil humification. Soil phenol oxidase and peroxidase enzyme activities were generally higher in the rich fen compared with the forest and bog birch sites. Results indicated greater C fluxes and more rapid C turnover in the surface soils of the fen sites compared to the wetland forest and shrub sites. Quantitative PCR analyses of soil bacteria and archaea, combined with enchytraeid counts, indicated that surface soils from the lowland fen ecosystems had higher abundances of these microbial and mesofaunal groups. Fungal abundance was highly variable and not significantly different among sites. Microbial data was utilized in a food web model that confirmed that rapidly cycling systems are dominated by bacterial activity and enchytraeid grazing. However, our results also suggest that oxidative enzymes play an important role in the C mineralization process in saturated systems, which has been often ignored.

  8. Dieldrin uptake by vegetable crops grown in contaminated soils.

    PubMed

    Donnarumma, Lucia; Pompi, Valter; Faraci, Alessandro; Conte, Elisa

    2009-06-01

    The aim of these trials was to study the distribution of dieldrin in soil and its translocation to roots and the aerial parts of vegetable crops grown in greenhouses and fields. The main objectives were to characterize dieldrin accumulation in plant tissues in relation to the levels of soil contamination; uptake capability among plants belonging to different species, varieties and cultivars. The presence of the contaminant was quantified by gas chromatography-electron capture detector (GC-ECD) and confirmed by gas chromatography-mass spectrometer (GC-MS). The results showed a translocation of residues in cucurbitaceous fruits and flowers confirming that zucchini, cucumber and melon are crops with high uptake capability. The maximum level of dieldrin residue at 0.01 mg/kg was found to be a threshold value to safeguard the quality production of cucurbits. Tomato, lettuce and celery were identified as substitute crops to grow in contaminated fields. PMID:20183049

  9. Interactions between soil moisture and Atmospheric Boundary Layer at the Brazilian savana-type vegetation Cerrado

    NASA Astrophysics Data System (ADS)

    Pinheiro, L. R.; Siqueira, M. B.

    2013-05-01

    Before the large people influx and development of the central part of Brazil in the sixties, due to new capital Brasília, Cerrado, a typical Brazilian savanna-type vegetation, used to occupy about 2 million km2, going all the way from the Amazon tropical forest, in the north of the country, to the edges of what used to be of the Atlantic forest in the southeast. Today, somewhat 50% of this area has given place to agriculture, pasture and managed forests. It is forecasted that, at the current rate of this vegetation displacement, Cerrado will be gone by 2030. Understanding how Cerrado interacts with the atmosphere and how this interaction will be modified with this land-use change is a crucial step towards improving predictions of future climate-change scenarios. Cerrado is a vegetation adapted to a climate characterized by two very distinct seasons, a wet season (Nov-Mar) and dry season (May-Ago), with April and October being transitions between seasons. Typically, based on measurements in a weather station located in Brasilia, 75% of precipitation happens in the wet-season months and only 5% during dry-season. Under these circumstances, it is clear that the vegetation will have to cope with long periods of water stress. In this work we studied using numerical simulations, the interactions between soil-moisture, responsible for the water stress, with the Atmospheric Boundary Layer (ABL). The numerical model comprises of a Soil-Vegetation-Atmosphere model where the biophysical processes are represented with a big-leaf approach. Soil water is estimated with a simple logistic model and with water-stress effects on stomatal conductance are parameterized from local measurements of simultaneous latent-heat fluxes and soil moisture. ABL evolution is calculate with a slab model that considers independently surface and entrainment fluxes of sensible- and latent- heat. Temperature tropospheric lapse-rate is taken from soundings at local airport. Simulations of 30-day dry down from saturation to complete water stress were performed and is analyzed as far how ABL respond to soil moisture changes. This provides informations about ABL behavior on the transition states. Future studies will look on how this behavior will change with the new vegetation covers.

  10. 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...

  11. Dynamics of deep soil moisture in response to vegetational restoration on the Loess Plateau of China

    NASA Astrophysics Data System (ADS)

    Jia, Yu-Hua; Shao, Ming-An

    2014-11-01

    The limitation of soil water in semiarid regions restricts the formation of a good cover of vegetation. The Loess Plateau in China, well known for its severe soil erosion, has a thick loessial soil that holds substantial volumes of water and provides the basis of a sustainable restoration of vegetation. Our limited understanding of the dynamics of deep soil moisture, however, could lead to the mismanagement of soil-water resources or could even misguide the policies of vegetational reconstruction. To evaluate the temporal response of deep soil moisture in different types of revegetation, we observed soil moisture to a depth of 340 cm in four plots, planted with Korshinsk peashrub (KOP), purple alfalfa (ALF), native plants (natural fallow, NAF), and millet (MIL), on 15 measurement events from 2010 to 2012. Our analysis provided four main conclusions. (1) The quantitative difference of potential evapotranspiration and actual precipitation resulted in natural deficits of soil moisture. The dynamics of deep soil moisture, however, were mainly dominated by the type of vegetation. Deep soils in plots of KOP and ALF became drier than the soil in plots of NAF and MIL. (2) Deep soil moisture in KOP and ALF was weakly variable. Correlations of time series of soil moisture between the upper and lower layers tended not to be significant. Dried soil layer, a special hydrological phenomenon, had formed in the plots. (3) The correlation between variances of soil moisture and the corresponding mean values were not always significantly positive due to the influence of vegetational type, observational depth, and date. (4) Fallow may be the best cover for achieving adequate hydrological sustainability of the soil. These results are expected to help improve the understanding of the response of deep soil moisture to vegetational restoration and to provide insight into the dynamics of deep soil moisture influenced by vegetation on loessial slopes.

  12. Vegetation and soils field research data base: Experiment summaries

    NASA Technical Reports Server (NTRS)

    Biehl, L. L.; Daughtry, C. S. T.; Bauer, M. E.

    1984-01-01

    Understanding of the relationships between the optical, spectral characteristics and important biological-physical parameters of earth-surface features can best be obtained by carefully controlled studies over fields and plots where complete data describing the condition of targets are attainable and where frequent, timely spectral measurement can be obtained. Development of a vegetation and soils field research data base was initiated in 1972 at Purdue University's Laboratory for Applications of Remote Sensing and expanded in the fall of 1974 by NASA as part of LACIE. Since then, over 250,000 truck-mounted and helicopter-borne spectrometer/multiband radiometer observations have been obtained of more than 50 soil series and 20 species of crops, grasses, and trees. These data are supplemented by an extensive set of biophysical and meteorological data acquired during each mission. The field research data form one of the most complete and best-documented data sets acquired for agricultural remote sensing research. Thus, they are well-suited to serve as a data base for research to: (1) quantiatively determine the relationships of spectral and biophysical characteristics of vegetation, (2) define future sensor systems, and (3) develop advanced data analysis techniques.

  13. The Aggregate Description of Semi-Arid Vegetation with Precipitation-Generated Soil Moisture Heterogeneity

    NASA Technical Reports Server (NTRS)

    White, Cary B.; Houser, Paul R.; Arain, Altaf M.; Yang, Zong-Liang; Syed, Kamran; Shuttleworth, W. James

    1997-01-01

    Meteorological measurements in the Walnut Gulch catchment in Arizona were used to synthesize a distributed, hourly-average time series of data across a 26.9 by 12.5 km area with a grid resolution of 480 m for a continuous 18-month period which included two seasons of monsoonal rainfall. Coupled surface-atmosphere model runs established the acceptability (for modelling purposes) of assuming uniformity in all meteorological variables other than rainfall. Rainfall was interpolated onto the grid from an array of 82 recording rain gauges. These meteorological data were used as forcing variables for an equivalent array of stand-alone Biosphere-Atmosphere Transfer Scheme (BATS) models to describe the evolution of soil moisture and surface energy fluxes in response to the prevalent, heterogeneous pattern of convective precipitation. The calculated area-average behaviour was compared with that given by a single aggregate BATS simulation forced with area-average meteorological data. Heterogeneous rainfall gives rise to significant but partly compensating differences in the transpiration and the intercepted rainfall components of total evaporation during rain storms. However, the calculated area-average surface energy fluxes given by the two simulations in rain-free conditions with strong heterogeneity in soil moisture were always close to identical, a result which is independent of whether default or site-specific vegetation and soil parameters were used. Because the spatial variability in soil moisture throughout the catchment has the same order of magnitude as the amount of rain failing in a typical convective storm (commonly 10% of the vegetation's root zone saturation) in a semi-arid environment, non-linearitv in the relationship between transpiration and the soil moisture available to the vegetation has limited influence on area-average surface fluxes.

  14. Vegetation modeled as a water cloud

    Microsoft Academic Search

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

    1978-01-01

    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

  15. Soil amendments reduce trace element solubility in a contaminated soil and allow regrowth of natural vegetation.

    PubMed

    Madejón, Engracia; de Mora, Alfredo Pérez; Felipe, Efraín; Burgos, Pilar; Cabrera, Francisco

    2006-01-01

    We tested the effects of three amendments (a biosolid compost, a sugar beet lime, and a combination of leonardite plus sugar beet lime) on trace element stabilisation and spontaneous revegetation of a trace element contaminated soil. Soil properties were analysed before and after amendment application. Spontaneous vegetation growing on the experimental plot was studied by three surveys in terms of number of taxa colonising, percentage vegetation cover and plant biomass. Macronutrients and trace element concentrations of the five most frequent species were analysed. The results showed a positive effect of the amendments both on soil chemical properties and vegetation. All amendments increased soil pH and TOC content and reduced CaCl(2)-soluble-trace element concentrations. Colonisation by wild plants was enhanced in all amended treatments. The nutritional status of the five species studied was improved in some cases, while a general reduction in trace element concentrations of the aboveground parts was observed in all treated plots. The results obtained show that natural assisted remediation has potential for success on a field scale reducing trace element entry in the food chain. PMID:16005126

  16. Seed rain, safe sites, competing vegetation, and soil resources spatially structure white pine

    E-print Network

    Hui, Bowen

    Seed rain, safe sites, competing vegetation, and soil resources spatially structure white pine of white pine (Pinus strobus L.) in aspen mixedwoods of the western Great Lakes region, U.S.A. Germin- ant on soil depths >5 cm. On deeper soil (~21 cm), overstory white pines occupied the shallowest soils (~18 cm

  17. Discrete random media techniques for microwave modeling of vegetated terrain

    NASA Technical Reports Server (NTRS)

    Lang, Roger H.

    1991-01-01

    Microwave remote sensing models of vegetated terrain are investigated. The problem is to determine canopy characteristics such as biomass, canopy height, and the moisture of the underlying soil. The report describes a discrete scatter model which has been employed to model backscatter in the active (radar) case and to model brightness temperature in the passive (radiometric) case. The acquisition of ground truth data is discussed, as well as the comparison of theory and experiment. The overall conclusion of the work has been that the discrete scatter model in conjunction with efficient scatter algorithms and the distorted Born approximation is a most appropriate methodology to use for modeling purposes in the microwave region.

  18. Heavy metals bioconcentration from soil to vegetables and assessment of health risk caused by their ingestion.

    PubMed

    Garg, V K; Yadav, Poonam; Mor, Suman; Singh, Balvinder; Pulhani, Vandana

    2014-03-01

    The present study was undertaken to assess the non-carcinogenic human health risk of heavy metals through the ingestion of locally grown and commonly used vegetables viz. Raphanus sativus (root vegetable), Daucus carota (root vegetable), Benincasa hispida (fruit vegetable) and Brassica campestris leaves (leafy vegetable) in a semi-urbanized area of Haryana state, India. Heavy metal quantification of soil and vegetable samples was done using flame atomic absorption spectrophotometer. Lead, cadmium and nickel concentration in vegetable samples varied in range of 0.12-6.54 mg kg(-1), 0.02-0.67 mg kg(-1) and <0.05-0.41 mg kg(-1), respectively. Cadmium and lead concentration in some vegetable samples exceeded maximum permissible limit given by World Health Organization/Food and Agriculture Organization and Indian standards. Much higher concentrations of Pb (40-190.5 mg kg(-1)), Cd (0.56-9.85 mg kg(-1)) and Ni (3.21-45.87 mg kg(-1)) were reported in corresponding vegetable fields' soils. Correlation analysis revealed the formation of three primary clusters, i.e. Cu-Cd, Cd-Pb and Ni-Zn in vegetable fields' soils further supported by cluster analysis and principal component analysis. Bioconcentration factor revealed that heavy metals' uptake was more by leafy vegetable than root and fruit vegetables. Hazard index of all the vegetables was less than unity; thus, the ingestion of these vegetables is unlikely to pose health risks to the target population. PMID:24464601

  19. Vegetative cover and PAHs accumulation in soils of urban green space.

    PubMed

    Peng, Chi; Ouyang, Zhiyun; Wang, Meie; Chen, Weiping; Jiao, Wentao

    2012-02-01

    We investigated how urban land uses influence soil accumulation of polycyclic aromatic hydrocarbons (PAHs) in the urban green spaces composed of different vegetative cover. How did soil properties, urbanization history, and population density affect the outcomes were also considered. Soils examined were obtained at 97 green spaces inside the Beijing metropolis. PAH contents of the soils were influenced most significantly by their proximity to point source of industries such as the coal combustion installations. Beyond the influence circle of industrial emissions, land use classifications had no significant effect on the extent of PAH accumulation in soils. Instead, the nature of vegetative covers affected PAH contents of the soils. Tree-shrub-herb and woodland settings trapped more airborne PAH and soils under these vegetative patterns accumulated more PAHs than those of the grassland. Urbanization history, population density and soil properties had no apparent impact on PAHs accumulations in soils of urban green space. PMID:22230065

  20. An update on remote measurement of soil moisture over vegetation using infrared temperature measurements: A FIFE perspective

    NASA Technical Reports Server (NTRS)

    Carlson, Toby N.

    1988-01-01

    Using model development, image analysis and micrometeorological measurements, the object is to push beyond the present limitations of using the infrared temperature method for remotely determining surface energy fluxes and soil moisture over vegetation. Model development consists of three aspects: (1) a more complex vegetation formulation which is more flexible and realistic; (2) a method for modeling the fluxes over patchy vegetation cover; and (3) a method for inferring a two-layer soil vertical moisture gradient from analyses of horizontal variations in surface temperatures. HAPEX and FIFE satellite data will be used along with aircraft thermal infrared and solar images as input for the models. To test the models, moisture availability and bulk canopy resistances will be calculated from data collected locally at the Rock Springs experimental field site and, eventually, from the FIFE project.

  1. Feasibility of using LANDSAT images of vegetation cover to estimate effective hydraulic properties of soils

    NASA Technical Reports Server (NTRS)

    Eagleson, P. S.

    1985-01-01

    Research activities conducted from February 1, 1985 to July 31, 1985 and preliminary conclusions regarding research objectives are summarized. The objective is to determine the feasibility of using LANDSAT data to estimate effective hydraulic properties of soils. The general approach is to apply the climatic-climax hypothesis (Ealgeson, 1982) to natural water-limited vegetation systems using canopy cover estimated from LANDSAT data. Natural water-limited systems typically consist of inhomogeneous vegetation canopies interspersed with bare soils. The ground resolution associated with one pixel from LANDSAT MSS (or TM) data is generally greater than the scale of the plant canopy or canopy clusters. Thus a method for resolving percent canopy cover at a subpixel level must be established before the Eagleson hypothesis can be tested. Two formulations are proposed which extend existing methods of analyzing mixed pixels to naturally vegetated landscapes. The first method involves use of the normalized vegetation index. The second approach is a physical model based on radiative transfer principles. Both methods are to be analyzed for their feasibility on selected sites.

  2. Vegetation Influences on Long-Term Carbon Stabilization in Soils: a Coast Redwood-Prairie Comparison

    NASA Astrophysics Data System (ADS)

    Mambelli, S.; Burton, S. D.; McFarlane, K. J.; Torn, M. S.; Dawson, T. E.

    2010-12-01

    Complex interactions and feedbacks among soil, biota, climate, and parent material determine the long-term pathways and mechanisms of carbon persistence in soils. While it is well known that litter chemistry influences litter decay on annual-decadal timescales, its impact on long-term SOM storage is still under debate. We tested the role of the substrate available to decomposers in determining decomposition and sequestration of carbon by comparing two contrasting ecosystems representing end-members in terms of tissue lifespan and litter recalcitrance, an old-growth redwood forest and an adjacent tree-less prairie, at one site with identical climate, topography, and parent material. Solid-state CP MAS 13C NMR was applied to investigate the chemical structure of vegetation tissues (aboveground and belowground), and of soil fractions (particulate organic carbon free in the soil matrix and particulate organic carbon located inside soil aggregates, or free and occluded light fraction (LF), respectively) at different depths. In addition, the carbon stability of these soil density fractions was estimated based on radiocarbon modeling. Preliminary NMR results showed strong differences between redwood and prairie tissues, and between litters and surface soil fractions. On average, redwood litter contained more aromatic carbon (C and O substituted aryl C), more lipids (alkyl C) and fewer carbohydrates (O-alkyl C) than prairie litter. Under both vegetation types we found that the chemical structure changed consistently from litter to free LF, and from free LF to occluded LF. The alkyl C signal intensity increased, while the O-alkyl C fraction decreased, but more strongly at the redwood forest. The proportion of aromatic functional groups in the total organic matter (aromaticity) was always higher in the soil fractions compared with the original litters. Redwood soil fractions aromaticity was 0.32 (+80% from litter), while prairie soil fractions aromaticity varied from 0.17 (free LF) to 0.23 (occluded LF)(+40 and +90% from litter, respectively). The proportion of carbon in carbonyl groups (alkyl/O-alkyl ratio), an estimate of the degree of decomposition, increased from the free LF to the occluded LF at both ecosystems (0.30 to 0.75 in the redwood forest, 0.24 to 0.68 in the prairie, respectively). In summary, the similar decomposition stage of the redwood and prairie SOM and the higher aromaticity of the free LF in the redwood soil compared to the original litter suggest the preservation of recalcitrant redwood constituents but only in the free soil matrix. Further investigations at deeper soil depths are underway.

  3. Historical influences on the vegetation and soils of the Martha's Vineyard, Massachusetts coastal sandplain

    E-print Network

    Von Holle, Betsy

    a major barrier to man- agement strategies that would involve conversion among any of these vegetationHistorical influences on the vegetation and soils of the Martha's Vineyard, Massachusetts coastal shrubland A B S T R A C T Both disturbance history and previous land use influence present-day vegetation

  4. Sensitivity of Three Vegetation Indices to Cimate and Soil moisture at a Tallgrass Prairie Site

    NASA Astrophysics Data System (ADS)

    Bajgain, R.; Xiao, X.; Wagle, P.; Basara, J. B.

    2014-12-01

    Climatic variability influence vegetation condition and growth, which are often characterized by satellite derived vegetation indices (VIs) such as normalized difference vegetation Index (NDVI), enhanced vegetation Index (EVI) and land surface water index (LSWI). A fourteen-year (2000 - 2013) of NDVI, EVI and LSWI data from Moderate-Resolution Imaging Spectroradiometer (MODIS) were analyzed for assessing grassland vegetation dynamics to climatic variability ( i.e., drought) and soil moisture over the time series at the Marena site, Stillwater Oklahoma,USA. This is also the Marena, Oklahoma In-situ Sensor Testbed (MOISST) site in support of NASA SMAP mission. Change in magnitudes of VIs provided the dynamics of inter-annual variability of the grassland vegetation. The magnitude of VIs declined in dry years (2006 and 2012) .Variation in NDVI and EVI over years resulting from climatic variability was strongly correlated to cumulative seasonal rainfall (NDVI, r = 0.82, EVI, r = 0.77) and average seasonal soil volumetric water content up to 60 cm depth. The EVI declined more than did NDVI during the dry events of 2006 and 2012, indicating that the use of EVI in place of NDVI appears to increase the performance of ecosystem models under drought condition. Furthermore, LSWI was the most sensitive index to drought among the three VIs tested. The LSWI values were negative (LSWI < 0) even within the middle of plant growing season in dry years, showing its potential to track the hydrological status of the ecosystem. Duration of LSWI < 0 in summer was greater in dry years (2006= 53 & 2012= 34 days) compared to wet years (2007 & 2013= 0 days). The result also revealed that LSWI values quantitatively corresponded well with the drought severity categories identified by the United States Drought Monitoring (USDM). In conclusion, the number of days with LSWI < 0 during the plant growing season and LSWI-based drought severity classification scheme can provide useful information for an assessment of the drought impacts over grasslands.

  5. 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)

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

    2009-04-01

    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.

  6. Use of LANDSAT images of vegetation cover to estimate effective hydraulic properties of soils

    NASA Technical Reports Server (NTRS)

    Eagleson, Peter S.; Jasinski, Michael F.

    1988-01-01

    This work focuses on the characterization of natural, spatially variable, semivegetated landscapes using a linear, stochastic, canopy-soil reflectance model. A first application of the model was the investigation of the effects of subpixel and regional variability of scenes on the shape and structure of red-infrared scattergrams. Additionally, the model was used to investigate the inverse problem, the estimation of subpixel vegetation cover, given only the scattergrams of simulated satellite scale multispectral scenes. The major aspects of that work, including recent field investigations, are summarized.

  7. Large-scale assessment of soil erosion in Africa: satellites help to jointly account for dynamic rainfall and vegetation cover

    NASA Astrophysics Data System (ADS)

    Vrieling, Anton; Hoedjes, Joost C. B.; van der Velde, Marijn

    2015-04-01

    Efforts to map and monitor soil erosion need to account for the erratic nature of the soil erosion process. Soil erosion by water occurs on sloped terrain when erosive rainfall and consequent surface runoff impact soils that are not well-protected by vegetation or other soil protective measures. Both rainfall erosivity and vegetation cover are highly variable through space and time. Due to data paucity and the relative ease of spatially overlaying geographical data layers into existing models like USLE (Universal Soil Loss Equation), many studies and mapping efforts merely use average annual values for erosivity and vegetation cover as input. We first show that rainfall erosivity can be estimated from satellite precipitation data. We obtained average annual erosivity estimates from 15 yr of 3-hourly TRMM Multi-satellite Precipitation Analysis (TMPA) data (1998-2012) using intensity-erosivity relationships. Our estimates showed a positive correlation (r = 0.84) with long-term annual erosivity values of 37 stations obtained from literature. Using these TMPA erosivity retrievals, we demonstrate the large interannual variability, with maximum annual erosivity often exceeding two to three times the mean value, especially in semi-arid areas. We then calculate erosivity at a 10-daily time-step and combine this with vegetation cover development for selected locations in Africa using NDVI - normalized difference vegetation index - time series from SPOT VEGETATION. Although we do not integrate the data at this point, the joint analysis of both variables stresses the need for joint accounting for erosivity and vegetation cover for large-scale erosion assessment and monitoring.

  8. The suitability of using leaf area index to quantify soil loss under vegetation cover

    Microsoft Academic Search

    Wentai Zhang; Dongsheng Yu; Xuezheng Shi; Hongjie Wang; Zhujun Gu; Xiangyan Zhang; Manzhi Tan

    2011-01-01

    Soil erosion by water under forest cover is a serious problem in southern China. A comparative study was carried out on the\\u000a use of leaf area index (LAI) and vegetation fractional coverage (VFC) in quantifying soil loss under vegetation cover. Five\\u000a types of vegetation with varied LAI and VFC under field conditions were exposed to two rainfall rates (40 mm

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

    NASA Astrophysics Data System (ADS)

    Ni, J.; Herzschuh, U.

    2009-04-01

    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.

  10. Directional infrared temperature and emissivity of vegetation: Measurements and models

    NASA Technical Reports Server (NTRS)

    Norman, J. M.; Castello, S.; Balick, L. K.

    1994-01-01

    Directional thermal radiance from vegetation depends on many factors, including the architecture of the plant canopy, thermal irradiance, emissivity of the foliage and soil, view angle, slope, and the kinetic temperature distribution within the vegetation-soil system. A one dimensional model, which includes the influence of topography, indicates that thermal emissivity of vegetation canopies may remain constant with view angle, or emissivity may increase or decrease as view angle from nadir increases. Typically, variations of emissivity with view angle are less than 0.01. As view angle increases away from nadir, directional infrared canopy temperature usually decreases but may remain nearly constant or even increase. Variations in directional temperature with view angle may be 5C or more. Model predictions of directional emissivity are compared with field measurements in corn canopies and over a bare soil using a method that requires two infrared thermometers, one sensitive to the 8 to 14 micrometer wavelength band and a second to the 14 to 22 micrometer band. After correction for CO2 absorption by the atmosphere, a directional canopy emissivity can be obtained as a function of view angle in the 8 to 14 micrometer band to an accuracy of about 0.005. Modeled and measured canopy emissivities for corn varied slightly with view angle (0.990 at nadir and 0.982 at 75 deg view zenith angle) and did not appear to vary significantly with view angle for the bare soil. Canopy emissivity is generally nearer to unity than leaf emissivity may vary by 0.02 with wavelength even though leaf emissivity. High spectral resolution, canopy thermal emissivity may vary by 0.02 with wavelength even though leaf emissivity may vary by 0.07. The one dimensional model provides reasonably accurate predictions of infrared temperature and can be used to study the dependence of infrared temperature on various plant, soil, and environmental factors.

  11. Microwave model prediction and verifications for vegetated terrain

    NASA Technical Reports Server (NTRS)

    Fung, A. K.

    1985-01-01

    To understand the scattering properties of a deciduous and a coniferous type vegetation scattering models were developed assuming either a disc type leaf or a needle type leaf. The major effort is to calculate the corresponding scattering phase functions and then each of the functions is used in a radiative transfer formulation to compute the scattering intensity and consequently the scattering coefficient. The radiative transfer formulation takes into account the irregular ground surface by including the rough soil surface in the boundary condition. Thus, the scattering model accounts for volume scattering inside the vegetation layer, the surface scattering from the ground and the interaction between scattering from the soil surface and the vegetation volume. The contribution to backscattering by each of the three scattering mechanisms is illustrated along with the effects of each layer or surface parameter. The major difference between the two types of vegetation is that when the incident wavelength is comparable to the size of the leaf there is a peak appearing in the mid angular region of the backscattering curve for the disc type leaf whereas it is a dip in the same region for a needle type leaf.

  12. Reflectance of vegetation, soil, and water. [in Hidalgo County, Texas

    NASA Technical Reports Server (NTRS)

    Wiegand, C. L. (principal investigator)

    1973-01-01

    The author has identified the following significant results. A study was conducted in a 340-acre (139 hectares) field of grain sorghum (Sorghum bicolor (L.) Moench) to determine if multispectral data from ERTS-1 could be used to detect differences in chlorophyll concentration between iron-deficient (chlorotic) and apparently normal (green) grain sorghum. Chlorotic sorghum areas 2.8 acres (1.1 hectares) or larger in size were identified on a computer printout of band 5 data which contains the chlorophyll absorption band at the 0.65 micron wavelength. ERTS resolution is sufficient for practical applications in detecting iron-deficient sorghum in otherwise uniform fields. The first classification map of the study county has been produced. Vegetation (crops), rangeland, bare soil, water, and an undefined (all other) category occupied 15.2, 45.0, 19.1, 0.02, and 20.6% of the land area, respectively.

  13. Grassland modeling and monitoring with SPOT4 VEGETATION instrument during the 1997–1999 SALSA experiment

    Microsoft Academic Search

    P. Cayrol; A. Chehbouni; L. Kergoat; G. Dedieu; P. Mordelet; Y. Nouvellon

    2000-01-01

    A coupled vegetation growth and soil–vegetation–atmosphere transfer (SVAT) model is used in conjunction with data collected in the course of the SALSA program during the 1997–1999 growing seasons in Mexico. The objective is to provide insights on the interactions between grassland dynamics and water and energy budgets. These three years exhibit drastically different precipitation regimes and thus different vegetation growth.The

  14. Characterizing the dependence of vegetation model parameters on crop structure, incidence angle, and polarization at L-band

    Microsoft Academic Search

    Jean-Pierre Wigneron; Mickael Pardé; Philippe Waldteufel; André Chanzy; Yann Kerr; Sten Schmidl; Niels Skou

    2004-01-01

    To retrieve soil moisture over vegetation-covered areas from microwave radiometry, it is necessary to account for vegetation effects. At L-band, many retrieval approaches are based on a simple model that relies on two vegetation parameters: the optical depth (?) and the single-scattering albedo (?). When the retrievals are based on multiconfiguration measurements, it is necessary to take into account the

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

    Microsoft Academic Search

    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

    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

  16. Evaluation of Landsat Multispectral Scanner data for mapping vegetated soil landscapes

    USGS Publications Warehouse

    Thompson, D. R.; Haas, Robert H.; Milford, M. H.

    1981-01-01

    Landsat multispectral scanner data for Brazos County, Texas, were evaluated in terms of effectiveness for classifying soils on vegetated landscapes at three times during the year: a time of normally adequate soil water, a time of expected soil water deficit, and a time when soil water is normally being replenished. Six test sites were used to evaluate LARSYS supervised and unsupervised classification of vegetated soil landscapes. Open grassland soils were best separated in the fall during a period when soil moisture was being replenished after the summer period of soil water deficit. Woodland soils were separated by Landsat data in late spring when adequate moisture was available. However, a high degree of accuracy was not achieved using Landsat for separating soil map units. Accurate separation of soil mapping units on vegetated landscapes was not possible during late summer when soil water was deficient. Selected soil properties important to plant growth were separable on the test sites using June and October Landsat data. Particle size and soil moisture regime were separated at both dates. Soils with argillic horizons were separated from soils without argillic horizons.

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

    Microsoft Academic Search

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

    2002-01-01

    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

  18. Radar backscattering measurement of bare soil and vegetation covered soil using X-band and full polarization

    NASA Astrophysics Data System (ADS)

    Goswami, B.; Kalita, M.

    2014-11-01

    The objective of the study is to measure backscattered power of bare soil and vegetation covered soil using X-band scatterometer system with full polarization and various angles during monsoon season and relate backscattered power to the density of vegetation over soil. The measurement was conducted at an experimental field located in the campus of Assam Engineering College, Guwahati, India. The soil sample consists of Silt and Clay in higher proportions as compared to Sand. The scatterometer system consists of dual-polarimetric square horn antennas, Power meter, Klystron, coaxial cables, isolator and waveguide detector. The polarization of the horn antennas as well as the look angle can be changed in the set-up. The backscattering coefficients were calculated by applying a radar equation for the measured values at incident angles between 30° and 60° for full polarization (HH, VV, HV, VH), respectively, and compared with vegetation cover over soil for each scatterometer measurement simultaneously. The VH polarization and 60° look angle are found to be the most suitable combination of configuration of an X-band scatterometer for distinguishing the land cover targets such as bare soil and vegetation covered soil. From the analysis of the results, polarimetric scatterometer data appear to be promising to distinguish the land cover types such as bare soil and soil completely covered by vegetation. The results of this study will help the scientists working in the field of active microwave remote sensing.

  19. Levels of metals in soils and vegetation in the vicinity of a municipal solid waste incinerator

    Microsoft Academic Search

    M. Schuhmacher; S. Granero; M. Bellés; J. M. Llobet; J. L. Domingo

    1996-01-01

    The concentrations of ten metals were determined in soil and vegetation samples collected in the vicinity of a municipal solid waste incinerator. Soil and common grass samples were obtained at various sites within 4 km from the incinerator. The potential exposure levels of neighborhood to metals was also investigated. In soils, the highest metal concentrations were found for Mn, Pb

  20. Assembly Processes under Severe Abiotic Filtering: Adaptation Mechanisms of Weed Vegetation to the Gradient of Soil Constraints

    PubMed Central

    Nikolic, Nina; Böcker, Reinhard; Kostic-Kravljanac, Ljiljana; Nikolic, Miroslav

    2014-01-01

    Questions Effects of soil on vegetation patterns are commonly obscured by other environmental factors; clear and general relationships are difficult to find. How would community assembly processes be affected by a substantial change in soil characteristics when all other relevant factors are held constant? In particular, can we identify some functional adaptations which would underpin such soil-induced vegetation response? Location Eastern Serbia: fields partially damaged by long-term and large-scale fluvial deposition of sulphidic waste from a Cu mine; subcontinental/submediterranean climate. Methods We analysed the multivariate response of cereal weed assemblages (including biomass and foliar analyses) to a strong man-made soil gradient (from highly calcareous to highly acidic, nutrient-poor soils) over short distances (field scale). Results The soil gradient favoured a substitution of calcicoles by calcifuges, and an increase in abundance of pseudometallophytes, with preferences for Atlantic climate, broad geographical distribution, hemicryptophytic life form, adapted to low-nutrient and acidic soils, with lower concentrations of Ca, and very narrow range of Cu concentrations in leaves. The trends of abundance of the different ecological groups of indicator species along the soil gradient were systematically reflected in the maintenance of leaf P concentrations, and strong homeostasis in biomass N:P ratio. Conclusion Using annual weed vegetation at the field scale as a fairly simple model, we demonstrated links between gradients in soil properties (pH, nutrient availability) and floristic composition that are normally encountered over large geographic distances. We showed that leaf nutrient status, in particular the maintenance of leaf P concentrations and strong homeostasis of biomass N:P ratio, underpinned a clear functional response of vegetation to mineral stress. These findings can help to understand assembly processes leading to unusual, novel combinations of species which are typically observed as a consequence of strong environmental filtering, as for instance on sites affected by industrial activities. PMID:25474688

  1. Modeling soil: realtime dynamic models for soil slippage and manipulation

    Microsoft Academic Search

    Xin Li; J. Michael Moshell

    1993-01-01

    A physically based model of an object is a mathematical representation of its behavior, which incorporates principles of Newtonian physics. Dynamic soil models are required in animations and realtime interactive simulations in which changes of natural terrain are involved. Analytic methods, based on soil properties and Newtonian physics, are presented in the paper to model soil slippage and soil manipulations.

  2. Evapotranspiration of soil water movement in small area vegetation

    NASA Astrophysics Data System (ADS)

    Paraskevas, C.; Georgiou, P.; Ilias, A.; Panoras, A.; Babajimopoulos, C.

    2013-12-01

    In Greece, crops are frequently cultivated in small isolated areas in close proximity to roads and bare soils and therefore evapotranspiration is affected by local advection. Under these circumstances, oasis effect conditions are present and evapotranspiration is higher than what is expected. In this paper, the evapotranspiration and soil water dynamics of a cotton crop cultivated in small areas under the oasis effect is studied. To this end, two isolated free-drainage lysimeters cultivated with cotton in the year 2007 were used. Soil moisture of the soil profile of both the lysimeters was monitored with two capacitance water content probes. The soil water balance method was used to estimate crop evapotranspiration and corresponding crop coefficients in one of the two lysimeters. These coefficients were 75% larger than the FAO-56 crop coefficients at the mid-season stage. The FAO-56 and the derived crop coefficients were used for the simulation of the water dynamics in the second lysimeter by the SWBACROS model. The derived crop coefficients for these conditions produced much better results than the FAO-56 crop coefficients. The results were improved when crop coefficient value equal to 2.5 was used for the mid-season stage.

  3. Integrated Analysis of Climate, Soil, Topography and Vegetative Growth in Iberian Viticultural Regions

    PubMed Central

    Fraga, Helder; Malheiro, Aureliano C.; Moutinho-Pereira, José; Cardoso, Rita M.; Soares, Pedro M. M.; Cancela, Javier J.; Pinto, Joaquim G.; Santos, João A.

    2014-01-01

    The Iberian viticultural regions are convened according to the Denomination of Origin (DO) and present different climates, soils, topography and management practices. All these elements influence the vegetative growth of different varieties throughout the peninsula, and are tied to grape quality and wine type. In the current study, an integrated analysis of climate, soil, topography and vegetative growth was performed for the Iberian DO regions, using state-of-the-art datasets. For climatic assessment, a categorized index, accounting for phenological/thermal development, water availability and grape ripening conditions was computed. Soil textural classes were established to distinguish soil types. Elevation and aspect (orientation) were also taken into account, as the leading topographic elements. A spectral vegetation index was used to assess grapevine vegetative growth and an integrated analysis of all variables was performed. The results showed that the integrated climate-soil-topography influence on vine performance is evident. Most Iberian vineyards are grown in temperate dry climates with loamy soils, presenting low vegetative growth. Vineyards in temperate humid conditions tend to show higher vegetative growth. Conversely, in cooler/warmer climates, lower vigour vineyards prevail and other factors, such as soil type and precipitation acquire more important roles in driving vigour. Vines in prevailing loamy soils are grown over a wide climatic diversity, suggesting that precipitation is the primary factor influencing vigour. The present assessment of terroir characteristics allows direct comparison among wine regions and may have great value to viticulturists, particularly under a changing climate. PMID:25251495

  4. Integrated Analysis of Climate, Soil, Topography and Vegetative Growth in Iberian Viticultural Regions

    NASA Astrophysics Data System (ADS)

    Fraga, Helder; Malheiro, Aureliano C.; Moutinho-Pereira, José; Cardoso, Rita M.; Soares, Pedro M. M.; Cancela, Javier J.; Pinto, Joaquim G.; Santos, João A.

    2015-04-01

    The Iberian viticultural regions are convened according to the Denomination of Origin (DO) and present different climates, soils, topography and management practices. All these elements influence the vegetative growth of different varieties throughout the peninsula, and are tied to grape quality and wine type. In the current study, an integrated analysis of climate, soil, topography and vegetative growth was performed for the Iberian DO regions, using state-of-the-art datasets. For climatic assessment, a categorized index, accounting for phenological/thermal development, water availability and grape ripening conditions was computed. Soil textural classes were established to distinguish soil types. Elevation and aspect (orientation) were also taken into account, as the leading topographic elements. A spectral vegetation index was used to assess grapevine vegetative growth and an integrated analysis of all variables was performed. The results showed that the integrated climate-soil-topography influence on vine performance is evident. Most Iberian vineyards are grown in temperate dry climates with loamy soils, presenting low vegetative growth. Vineyards in temperate humid conditions tend to show higher vegetative growth. Conversely, in cooler/warmer climates, lower vigour vineyards prevail and other factors, such as soil type and precipitation acquire more important roles in driving vigour. Vines in prevailing loamy soils are grown over a wide climatic diversity, suggesting that precipitation is the primary factor influencing vigour. The present assessment of terroir characteristics allows direct comparison among wine regions and may have great value to viticulturists, particularly under a changing climate.

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

    USGS Publications Warehouse

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

    2008-01-01

    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.

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

    Microsoft Academic Search

    P. R. Warman

    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

  7. Establishing an International Soil Modelling Consortium

    NASA Astrophysics Data System (ADS)

    Vereecken, Harry; Schnepf, Andrea; Vanderborght, Jan

    2015-04-01

    Soil is one of the most critical life-supporting compartments of the Biosphere. Soil provides numerous ecosystem services such as a habitat for biodiversity, water and nutrients, as well as producing food, feed, fiber and energy. To feed the rapidly growing world population in 2050, agricultural food production must be doubled using the same land resources footprint. At the same time, soil resources are threatened due to improper management and climate change. Soil is not only essential for establishing a sustainable bio-economy, but also plays a key role also in a broad range of societal challenges including 1) climate change mitigation and adaptation, 2) land use change 3) water resource protection, 4) biotechnology for human health, 5) biodiversity and ecological sustainability, and 6) combating desertification. Soils regulate and support water, mass and energy fluxes between the land surface, the vegetation, the atmosphere and the deep subsurface and control storage and release of organic matter affecting climate regulation and biogeochemical cycles. Despite the many important functions of soil, many fundamental knowledge gaps remain, regarding the role of soil biota and biodiversity on ecosystem services, the structure and dynamics of soil communities, the interplay between hydrologic and biotic processes, the quantification of soil biogeochemical processes and soil structural processes, the resilience and recovery of soils from stress, as well as the prediction of soil development and the evolution of soils in the landscape, to name a few. Soil models have long played an important role in quantifying and predicting soil processes and related ecosystem services. However, a new generation of soil models based on a whole systems approach comprising all physical, mechanical, chemical and biological processes is now required to address these critical knowledge gaps and thus contribute to the preservation of ecosystem services, improve our understanding of climate-change-feedback processes, bridge basic soil science research and management, and facilitate the communication between science and society . To meet these challenges an international community effort is required, similar to initiatives in systems biology, hydrology, and climate and crop research. We therefore propose to establish an international soil modelling consortium with the aims of 1) bringing together leading experts in modelling soil processes within all major soil disciplines, 2) addressing major scientific gaps in describing key processes and their long term impacts with respect to the different functions and ecosystem services provided by soil, 3) intercomparing soil model performance based on standardized and harmonized data sets, 4) identifying interactions with other relevant platforms related to common data formats, protocols and ontologies, 5) developing new approaches to inverse modelling, calibration, and validation of soil models, 6) integrating soil modelling expertise and state of the art knowledge on soil processes in climate, land surface, ecological, crop and contaminant models, and 7) linking process models with new observation, measurement and data evaluation technologies for mapping and characterizing soil properties across scales. Our consortium will bring together modelers and experimental soil scientists at the forefront of new technologies and approaches to characterize soils. By addressing these aims, the consortium will contribute to improve the role of soil modeling as a knowledge dissemination instrument in addressing key global issues and stimulate the development of translational research activities. This presentation will provide a compelling case for this much-needed effort, with a focus on tangible benefits to the scientific and food security communities.

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

    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.

  9. Using GPS Interferometric Reflectometry to estimate soil moisture and vegetation water content fluctuations

    NASA Astrophysics Data System (ADS)

    Chew, C. C.; Small, E. E.; Larson, K. M.; Braun, J. J.; Shreve, C. M.

    2010-12-01

    High-precision GPS receivers can be used to estimate fluctuations in near surface soil moisture, snow and vegetation water content. This approach, referred to as GPS-Interferometric Reflectometry (GPS-IR), relates precise changes in the geometry of reflected GPS signals to observe soil moisture and snow while simultaneously using signal attenuation and diffuse scattering to infer changes in vegetative state. Previous remote sensing research has shown that microwave signals (e.g., L-band) are optimal for measuring hydrologic variables, such as soil moisture, and because GPS satellites transmit similar signals, they can be useful for sensing water in the environment. In addition, standard GPS antenna configurations that are used in NSF's Plate Boundary Observatory network yield sensing footprints of ~1000 m2. Given this sensitivity, hundreds of GPS receivers that exist in the U.S. could be used to provide near-real time estimates of soil moisture and vegetation water content for satellite validation, drought monitoring and related studies. A significant obstacle to using L-band (or similar) signals for remote sensing is differentiating the effects of soil moisture and vegetation on the retrieval of hydrologic variables. This same challenge exists when using GPS-IR data. We have established nine research sites with identical GPS and hydrologic infrastructure to study this problem. These sites span a wide range of soil, vegetation, and climate types. In addition to daily GPS and hourly soil moisture data, we have collected weekly vegetation water content samples at all sites. Our data demonstrate that soil moisture fluctuations can be estimated from GPS-IR records when vegetation water content is low (< 2 kg m-2). We outline different approaches for separating the soil moisture and vegetation signals and quantifying errors in our retrieval algorithm.

  10. Role of native and exotic woody vegetation in soil restoration in active gully systems (southern Ecuador)

    NASA Astrophysics Data System (ADS)

    Borja Ramon, Pablo; Alvarado Moncayo, Dario; Vanacker, Veerle; Cisneros, Pedro; Molina, Armando; Govers, Gerard

    2015-04-01

    Revegetation projects in degraded lands have the potential to recover essential soil functions. If vegetation restoration is combined with bioengineering techniques, such as the construction of retention dams in active gully systems, soil restoration could be enhanced. One important aspect of this process is the role of vegetation on restoration of soil chemical and physical properties. There is currently a lack of knowledge on the potential of soil restoration in active badland systems, as most studies have concentrated on the direct and visible effect of revegetation on erosion control. The aim of this study is to evaluate the role of revegetation and bioengineering works on the restoration of soil physical and chemical properties. The analyses are realized in a highly degraded area of 3 km2, located in the lower part of the Loreto catchment (Southern Ecuadorian Andes). First, the soil physical and/or chemical parameters that are most sensitive to track environmental change were evaluated. Second, the role of vegetation on soil restoration was quantified. . Soil samples were taken in sites with different vegetation cover, land use and physiographic position. The following physical and chemical parameters were measured: volumetric water content (?sat, ?act), bulk density, pH, texture, organic matter, C and N content. Our first results do not show a clear relationship between volumetric water content at saturation (?sat), bulk density, or C content. The saturation water content does not vary significantly between different sites, or land use types. However, significant differences are found between sites at different stages of restoration; and this for most chemical and physical soil properties. Vegetation cover (%) appears to exert a strong control on the C content in the mineral soils. The highest C values are found in soils of forest plantations with Eucalyptus and Pinus species. These plantations are located in areas that were previously affected by active gullying. Our results show that the establishment of a protective vegetation cover is an important factor in soil restoration.

  11. The N transformation mechanisms for rapid nitrate accumulation in soils under intensive vegetable cultivation

    Microsoft Academic Search

    Tongbin Zhu; Jinbo Zhang; Zucong Cai; Christoph Müller

    Purpose  Rapid soil degradation occurring under intensive vegetable cultivation, an increasingly common agricultural strategy in China,\\u000a is characterized by soil acidification, salinity, and NO3? accumulation. However, to date, the reasons for rapid NO3? accumulation in soils at the nitrogen (N) levels have not been completely understood. In this study, we explored the underlying\\u000a mechanisms for rapid NO3? accumulation in soils used

  12. Soil macroinvertebrates' abundance and diversity in home gardens in Tabasco, Mexico, vary with soil texture, organic matter and vegetation cover

    Microsoft Academic Search

    E. Huerta; Wal van der J. C

    2012-01-01

    We studied the composition of soil invertebrate communities and vegetation in 50 home gardens in the humid tropical lowlands of Tabasco, Mexico, located in five geomorphological regions. Five monoliths were made in each home garden and soil invertebrates were hand sorted, weighed and classified to morhospecies, functional groups and orders. We determined pH, organic matter, available phosphorus and texture in

  13. Microwave Dielectric Properties of Soil and Vegetation and Their Estimation From Spaceborne Radar

    NASA Technical Reports Server (NTRS)

    Dobson, M. Craig; McDonald, Kyle C.

    1996-01-01

    This paper is largely tutorial in nature and provides an overview of the microwave dielectric properties of certain natural terrestrial media (soils and vegetation) and recent results in estimating these properties remotely from airborne and orbital synthetic aperture radar (SAR).

  14. [Characteristics of soil microbial community under different vegetation types in Wuyishan National Nature Reserve, East China].

    PubMed

    Wu, Ze-yan; Lin, Wen-xiong; Chen, Zhi-fang; Fang, Chang-xun; Zhang, Zhi-xing; Wu, Lin-kun; Zhou, Ming-ming; Shen, Li-hua

    2013-08-01

    By using Biolog Ecoplate system, this paper studied the structure and functional diversity of soil microbial community under different vegetation types in Wuyishan National Nature Reserve, aimed to probe into the effects of vegetation type on the diversity of soil microbial community. The results showed that the soil chemical properties, soil enzyme activities, and average well color development (AWCD) were higher in natural forest than in planted forest, and were the lowest in abandoned field. The AWCD reflecting soil microbial activity and functional diversity was increased with increasing incubation time, but there existed significant differences among different vegetation types. The carbon sources mostly used by soil microbes were carbohydrates and carboxylic acids, followed by amino acids, phenolic acids and polymers, and amines had the lowest utilization rate. The Simpson index, Shannon index, Richness index and McIntosh index in natural forest were holistically higher than those in planted forest. Principal component analysis (PCA) identified 2 principal component factors in relation to carbon sources, explaining 56.3% and 30.2% of the variation, respectively. The carbon sources used by soil microbial community differed with vegetation types. Amino acids and amides were the two main carbon sources separating the 2 principal component factors. The results of this study could provide basis for further approaching the relationships between vegetation diversity and soil microbial community diversity. PMID:24380352

  15. Phytoavailability of thallium - A model soil experiment

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    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.

  16. Topographical and biophysical modeling of vegetation patterns at alpine treeline

    SciTech Connect

    Brown, D.G.

    1992-01-01

    Availability and abundance of several important topo-climatic elements explains much of the variation in the patterns of vegetation along the treeline ecotone. Active geomorphic and biophysical disturbance regimes in alpine areas introduce additional variability on the treeline transition. The purpose of this research was to model the spatial patterns of vegetation communities along the treeline ecotone relative to topo-climatic and disturbances processes. Surrogates of several topographically controlled climatic elements (solar radiation potential, soil moisture potential, and wind/snow potential) were constructed from digital elevation models (DEMs) for a study area in east-central Glacier National Park, Montana. Vegetation communities in the study area were characterized through statistical classification of Landsat Thematic Mapper digital data, field calibration, and validation. Topographical empirical Models of Treeline (TEMTREEs) were constructed to examine the relative importance of factors which affected the treeline transition. TEMTREEs were also evaluated as predictive tools for extending the analysis through additional variables representing multi-scale processes. Empirical models were constructed for selected elevation zones (from 1600 to 2350 meters a.m.s.l.) at 150 meter intervals. The Kappa statistic was used to assess the predictive ability of the models. The results suggested that the elevation gradient accounted for much of the variation in the vegetation patterns at alpine treeline. Geomorphic disturbance patterns, characterized by mapping talus slopes, snow avalanche paths, and slope angles greater than 34 degrees, consistently explained significant variations in the vegetation patterns. This finding suggests that predictions of treeline responses to climatic change must account for potential changes in the frequency and magnitude of geomorphic process disturbances.

  17. Precontact vegetation and soil nutrient status in the shadow of Kohala Volcano, Hawaii

    Microsoft Academic Search

    Oliver A. Chadwick; Eugene F. Kelly; Sara C. Hotchkiss; Peter M. Vitousek

    2007-01-01

    Humans colonized Hawaii about 1200 years ago and have progressively modified vegetation, particularly in mesic to dry tropical forests. We use ?13C to evaluate the contribution of C3 and C4 plants to deep soil organic matter to reconstruct pre-human contact vegetation patterns along a wet to dry climate transect on Kohala Mountain, Hawaii Island. Precontact vegetation assemblages fall into three distinct

  18. Suppression of Allium white rot ( Sclerotium cepivorum ) in different soils using vegetable wastes

    Microsoft Academic Search

    E. Coventry; R. Noble; A. Mead; J. M. Whipps

    2005-01-01

    Mixtures of wet vegetable wastes (Brassica, carrot or onion) and dry onion waste were composted at 50 °C for 7 days. The incorporation of the raw or composted vegetable waste mixtures into sandy loam, silt and peat soils reduced the viability of sclerotia of S. cepivorum in glasshouse pot bioassays. The reduction in viability was dependent on waste type, rate

  19. FOOD FOR EAmY SUCCESSION BIRDS: RELATIONSHIPS AMONG ARTHROPODS, SHRUB VEGETATION, AND SOIL

    Microsoft Academic Search

    RICHARD N. CONNER; DANIEL SAENZ

    During spring and early summer, shrub- and herbaceous-level vegetation pro- vides nesting and foraging habitat for many shrub-habitat birds. We examined relationships among arthropod biomass and abundance, foliage leaf surface area and weight, vegetation ground cover, soil characteristics, relative humidity, and temperature to evaluate what factors may influence arthropod food resources for birds. Relative humidity was inversely associated with arthropod

  20. A THERMODYNAMIC CHARACTERIZATION OF VEGETATION AND SOIL FEEDBACKS IN THE CLIMATE SYSTEM

    Microsoft Academic Search

    Axel Kleidon

    Terrestrial vegetation affects soil and surface properties over land, and thereby modulates the ex- change fluxes of energy, water and carbon between the land surface and the overlying atmosphere. When compared to a bare surface, green forest canopies absorb more solar radiation, are aerody- namically rougher, and have a higher ability to transpire water. Below the ground, vegetation can reach

  1. An Idealized Model of Plant and Soil Dynamics

    NASA Astrophysics Data System (ADS)

    Burg, David; Malkinson, Dan; Wittenberg, Lea

    2014-05-01

    Following wildfire events the landscape commonly becomes denuded of vegetation cover, resulting in systems prone to soil loss and degradation. In this context soil dynamics are an intricate process balanced between pedogenesis, which is a relatively slow process and erosion which depends on many inert (e.g. soil texture, slope, precipitation and wind) and biological factors such as vegetation properties, grazing intensity, and human disturbance. We develop a simple homogenous, spatially implicit, theoretical model of the global dynamics of the interactions between vegetation and soil using a system of two nonlinear differential equations describing this interdependence, assuming a double feedback between them - plants control erosion and soil availability facilitates plants growth: ( ) dV- -K-- dt = rV K - 1+ aS - V (1) dS-= ? - ?Se-cT dt (2) where V and S represent vegetation cover and soil availability, respectively. Vegetation growth is similar to the classical logistic model with a growth rate of r(yr1), however, the "carrying capacity" (K) is dependent on soil availability (a1 is the amount of soil where V is reduced by half). Soil influxes at a constant rate ?(mm×yr1) and is eroded at a constant rateg? (yr-1), while vegetation abates this process modeled as a decreasing exponent as the effectiveness of vegetation in reducing soil erosion (c). Parameter values were chosen from a variable range found in the literature: r=0.01 yr1, K=75%, a1=1, ?=1 mm×yr1, ?=0.1 yr1, c=0.08. Complex properties emerge from this model. At certain parameter values (cK?4) the model predicts one of two steady states - full recovery of vegetation cover or a degraded barren system. However, at certain boundary conditions (cK>4 and ?1 ? ?/? ? ?2, see Article for terms of ?1 and ?2) bistability may be observed. We also show that erosion seems to be the determining factor in this system, and we identify the threshold values from which beyond the systems become unstable. The model predicts that certain ecosystems will be highly stable in one of two states, while others might be bistable transitioning between these two states through perturbations. This is an indicator of hysteresis, possibly indicating the ability of the system to shift leading to sudden and dramatic changes; formalizing the conceptual model shown by Davenport et al. (1998) and others. Following the establishment of these interrelationships, the role of repeated disturbances, such as wildfires, was assessed with numerical analysis in determining the long term dynamics of coupled soil-vegetation systems.

  2. Changes in regional boreal climate due to historic and future structural vegetation changes and variations in soil moisture memory

    NASA Astrophysics Data System (ADS)

    Rydsaa, Johanne H.; Stordal, Frode; Tallaksen, Lena M.

    2014-05-01

    Amplified warming at high latitudes over the past decades already has led to, and will continue to lead to, changes in the boreal and arctic part of the climate system. Climate change induced alterations include structural shifts in high latitude ecosystems such as boreal forest expansion towards higher latitudes and altitudes, and shrub-ecosystems replacing tundra in large areas of the arctic. These shifts affect surface physical qualities such as albedo, roughness length, and soil properties. Shifts in vegetation species may also lead to alterations in soil- and boundary layer moisture. Resultant changes in land surface properties and processes provide important feedbacks to regional climate by changes in radiation, and water and energy fluxes. Structural vegetation changes that appear on local scale may through these feedback mechanisms also propagate to affect large scale climatic features. In this study, the Weather Research and Forecasting model (WRF) with the Noah Land surface model is used in a series of experiments in order to investigate the influence of observed and anticipated structural changes in the boreal ecosystem on changes in the land-atmosphere feedbacks. MODIS land surface data are used together with observational data and dynamical vegetation model output from the CMIP5 database, to simulate the influence of historical and future structural vegetation changes over the Northern European Boreal domain. In a series of three experiments the MODIS dataset is manually altered in order to reflect observed and anticipated changes in Boreal forest geography on summer water and energy fluxes at the surface, including Bowen ratio changes. As results are highly sensitive to soil moisture variations, experiments are conducted under wet and dry soil moisture regimes, to take into account uncertainties in future soil state projections and to estimate sensitivity to soil moisture memory in surface flux estimates.

  3. Role of vegetation in modulating rainfall interception and soil water flux in ecosystems under transition from grassland to woodland

    NASA Astrophysics Data System (ADS)

    Zou, Chris; Will, Rodney; Stebler, Elaine; Qiao, Lei

    2014-05-01

    Vegetation exerts strong control on the hydrological budget by shielding the soil from rainfall through interception and modulating water transmission in the soil by altering soil properties and rooting zone water extraction. Therefore, a change in vegetation alters the water cycle by a combination of a passive, rainfall redistribution mechanism controlled by the physical dimensions of vegetation and active, water extracting processes resulting from physiological attributes of different plants. As a result, the role of vegetation on the water cycle is likely to change where vegetation is under transition such as in the southern Great Plains of USA due to woody plant encroachment. However, it remains largely unknown how this physiognomic transformation from herbaceous cover to woody canopy alters rainfall influx, soil water transmission and efflux from the soil profile and consequently alters historic patterns of runoff and groundwater recharge. This knowledge is critical for both water resource and ecosystem management. We conducted a comprehensive, 5-year study involving direct quantification of throughfall and stemflow for grassland and encroached juniper woodland (Juniperus virginiana), water efflux through transpiration using an improved Granier thermal dissipation method (trees) and ET chamber (grassland), soil moisture storage and dynamics (capacitance probe) and streamflow (small catchment). We calibrated a prevailing hydrological model (SWAT) based on observed data to simulate potential change in runoff and recharge for the Cimarron River basin (study site located within this basin) under various phases of grassland to woodland transition. Our results show that juniper encroachment reduces throughfall reaching the soil surface compared with grassland under moderate grazing. The evergreen junipers transpired water year-round including fall and winter when the warm season grasses were senescent. As a result, soil water content and soil water storage on the encroached catchment were generally lower than on the grassland catchment, especially proceeding the seasons of peak rainfall in spring and fall. Frequency and magnitude of streamflow events was observed to be substantially reduced in the encroached catchment. Model simulation suggests that conversion of all existing grassland to juniper in the Cimarron River basin will increase overall water efflux through evapotranspiration sufficient to substantially reduce water yield for streamflow. Rapid transformation of mesic grasslands to a woodland state with juniper encroachment, if not confined, has the potential to reduce soil water, streamflow and flow duration of ephemeral streams. Slowing the expansion of woody encroachment into grasslands might be considered as a land-based strategy to sustain or even augment streamflow and groundwater recharge to meet the increase in water demand under increasing climate variability and population growth in the southern Great Plains of USA

  4. Floristic Composition of Vegetation and the Soil Seed Bank in Different Types of Dunes of Kerqin Steppe

    Microsoft Academic Search

    Yulin Li; Jianyuan Cui; Xueyong Zhao; Halin Zhao

    2004-01-01

    The floristic composition of the vegetation and the soil seed bank in different types of dunes of Kerqin steppe were compared. The aim of this study was to examine the influence of desertification on the floristic composition of the vegetation and soil seed bank. An indirect germination method was used to study the seed bank. Thirty species of the vegetation

  5. Bioremediation of petroleum contaminated soil using vegetation. A microbial study

    SciTech Connect

    Lee, E.; Banks, M.K. (Kansas State Univ., Manhattan, KS (United States))

    1993-12-01

    The degradation of selected petroleum hydrocarbons in the rhizosphere of alfalfa was investigated in a greenhouse experiment. Petroleum contaminated and uncontaminated soils were spiked with 100 ppm of polynuclear aromatic and aliphatic hydrocarbons. Unspiked, uncontaminated soil was used as a control. Microbial counts for soils with and without plants for each soil treatment were performed 4, 8, 16, and 24 weeks after planting. Microbial numbers were substantially greater in soil with plants when compared to soil containing no plants, indicating that plant roots enhanced microbial populations in contaminated soil. Soil treatments had no effect on microbial numbers in the presence of plants. 12 refs., 3 figs., 1 tab.

  6. Temporal Variations in Soil Moisture for Three Typical Vegetation Types in Inner Mongolia, Northern China

    PubMed Central

    Zheng, Hao; Gao, Jixi; Teng, Yanguo; Feng, Chaoyang; Tian, Meirong

    2015-01-01

    Drought and shortages of soil water are becoming extremely severe due to global climate change. A better understanding of the relationship between vegetation type and soil-moisture conditions is crucial for conserving soil water in forests and for maintaining a favorable hydrological balance in semiarid areas, such as the Saihanwula National Nature Reserve in Inner Mongolia, China. We investigated the temporal dynamics of soil moisture in this reserve to a depth of 40 cm under three types of vegetation during a period of rainwater recharge. Rainwater from most rainfalls recharged the soil water poorly below 40 cm, and the rainfall threshold for increasing the moisture content of surface soil for the three vegetations was in the order: artificial Larix spp. (AL) > Quercus mongolica (QM) > unused grassland (UG). QM had the highest mean soil moisture content (21.13%) during the monitoring period, followed by UG (16.52%) and AL (14.55%); and the lowest coefficient of variation (CV 9.6-12.5%), followed by UG (CV 10.9-18.7%) and AL (CV 13.9-21.0%). QM soil had a higher nutrient content and higher soil porosities, which were likely responsible for the higher ability of this cover to retain soil water. The relatively smaller QM trees were able to maintain soil moisture better in the study area. PMID:25781333

  7. The Changing Model of Soil

    NASA Astrophysics Data System (ADS)

    Richter, D. D.; Yaalon, D.

    2012-12-01

    The contemporary genetic model of soil is changing rapidly in response to advances in soil science and to human and environmental forcings in the 21st century (Richter and Yaalon, 2012). Three ongoing changes in the model of soil include that: (1) lower soil boundaries are much deeper than the solum, historically the O to B horizons, (2) most soils are polygenetic paleosols, products of soil-forming processes that have ranged widely over soils' lifetimes, and (3) soils are globally human-natural bodies, no longer natural bodies. Together, these changes in the model of soil mean that human forcings are a global wave of soil polygenesis altering fluxes of matter and energy and transforming soil thermodynamics as potentially very deep systems. Because soils are non-linear systems resulting from high-order interactions of physics, chemistry, and biology, trajectories of how human forcings alter soils over decades are not readily predictable and require long-term soil observations. There is much to learn about how soils are changing internally as central components of management systems and externally in relation to wider environments. To be critical, research has been remarkably superficial in studies of soil, reductionist in approach, and lacking in time-series observations of responses to soil management. While this criticism may sound negative, it creates significant opportunities for contemporary soil scientists.

  8. [Characteristics of soil microelements contents in the rhizospheres of different vegetation in hilly-gully region of Loess Plateau].

    PubMed

    Zhang, Chao; Liu, Guo-Bin; Xue, Sha; Zhang, Chang-Sheng

    2012-03-01

    To explore the rhizosphere effect of the microelements in the soils under different vegetation types in Loess Plateau, this paper analyzed the organic C, total N, Mn, Cu, Fe, and Zn contents in the rhizosphere soil and bulk soil of six vegetation types in hilly-gully region of Loess Plateau. Among the six vegetation types, Caragana korshinskii, Heteropappus altaicus, and Artemisia capillaries had higher organic C and total N contents in rhizosphere soil than in bulk soil. With the exception of C. korshinskii and H. rhamnoides, all the six vegetation types had a significantly lower pH in rhizosphere soil than in bulk soil. The six vegetation types had a lower available Mn content in rhizosphere soil than in bulk soil, and the C. korshinskii, Astragalus adsurgen, and Panicum virgatum had a significantly higher available Cu content in rhizosphere soil than in bulk soil. The six vegetation types except A. adsurgens had a slightly higher available Fe content in rhizosphere soil than in bulk soil, and A. adsurgens, P. virgatum, H. altaicus, and A. capillaries had a significant accumulation of available Zn in rhizosphere soil. There existed significant positive correlations between the rhizosphere soil and bulk soil of the six vegetation types in the relationships between the organic C and total N contents and the available Mn and Zn contents and between the contents of available Mn and Zn. In rhizosphere soil, available Mn and Zn contents were significantly negative- ly correlated with pH value. Due to the differences in root growth characteristics, rhizosphere pH value, and microbial structure composition, the microelements contents in the rhizosphere soil of the six vegetation types differed, with the contents of Mn, Cu, Fe, and Zn being higher in the rhizosphere soil of H. altaicus than in that of the other vegetation types. PMID:22720606

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

    NASA Astrophysics Data System (ADS)

    Port, Ulrike; Claussen, Martin

    2013-04-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    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.

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

    PubMed

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

    2009-02-01

    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

  12. A multi-frequency radiometric measurement of soil moisture content over bare and vegetated fields

    NASA Technical Reports Server (NTRS)

    Wang, J. R.; Schmugge, T. J.; Mcmurtrey, J. E., III; Gould, W. I.; Glazar, W. S.; Fuchs, J. E. (principal investigators)

    1981-01-01

    A USDA Beltsville Agricultural Research Center site was used for an experiment in which soil moisture remote sensing over bare, grass, and alfalfa fields was conducted over a three-month period using 0.6 GHz, 1.4 GHz, and 10.6 GHz Dicke-type microwave radiometers mounted on mobile towers. Ground truth soil moisture content and ambient air and sil temperatures were obtained concurrently with the radiometric measurements. Biomass of the vegetation cover was sampled about once a week. Soil density for each of the three fields was measured several times during the course of the experiment. Results of the radiometric masurements confirm the frequency dependence of moisture sensing sensitivity reduction reported earlier. Observations over the bare, wet field show that the measured brightness temperature is lowest at 5.0 GHz and highest of 0.6 GHz frequency, a result contrary to expectation based on the estimated dielectric permittivity of soil water mixtures and current radiative transfer model in that frequency range.

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

    Microsoft Academic Search

    Nico Eisenhauer; Stephan Partsch; Dennis Parkinson; Stefan Scheu

    2007-01-01

    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

  14. Relationship between vegetation and soil seed banks in an arctic coastal marsh

    Microsoft Academic Search

    E. R. Chang; R. L. Jefferies; T. J. Carleton

    2001-01-01

    Summary 1 The effects of habitat degradation on the soil seed bank at La Pérouse Bay, Manitoba are described. Foraging by lesser snow geese leads to loss of vegetation, coupled with changes in soil abiotic conditions and an increase in salinity. 2 The density of seeds and the relative abundance in the seed bank of species charac- teristic of undisturbed

  15. Reclaiming Hard Rock Mines: An In Depth Look at Vegetation, Soil, and Water on the Bullion

    E-print Network

    Maxwell, Bruce D.

    Reclaiming Hard Rock Mines: An In Depth Look at Vegetation, Soil, and Water on the Bullion Mine, nine miles north of Basin, Montana, the hard rock Bullion Mine produced gold, silver, lead, zinc with tailings piles, waste rock and acid mine drainage (AMD; Figure 1). Waste rock, the soil and rock material

  16. Heavy Metal Contamination of Soil and Vegetation in the Vicinity of Industries in Bangladesh

    Microsoft Academic Search

    M. D. Abul Kashem; Bal Ram Singh

    1999-01-01

    A study was conducted to investigate the heavy metal contamination of soil and vegetation in the vicinity of industries around Dhaka city in Bangladesh. Categorically soils, grass (Cynoden doctylon L), water hyacinth (Eichhornia crassipes L), rice (Oryza sative L), and arum (Alocasia esculenta L) were collected from tannery, ceramic, textile dying and sulphuric acid producing industrial sites. The concentrations of

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

    Microsoft Academic Search

    Marilyn J. Buchauer

    1973-01-01

    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

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

    E-print Network

    Raman, Sethu

    Sensitivity of Mesoscale Surface Dynamics to Surface Soil and Vegetation Contrasts over in mesoscale summertime precipitation over this region. Numerical simulations are analyzed to investigate the relationships between mesoscale surface dynamics and the transition from clay to sandy soils over this region

  19. Wildfire Effects on Vegetation and Soils at the Purdy Fire Site, Gallatin National Forest

    E-print Network

    Maxwell, Bruce D.

    Wildfire Effects on Vegetation and Soils at the Purdy Fire Site, Gallatin National Forest Photo nitrogen, available phosphorous, and other macro- and micronutrients (Hungerford et al. 1990). Soil nitrate, and leaching of water-soluble nutrients typically reduce nitrate levels to pre-burn conditions within one year

  20. The vegetation of ultrabasic soils on the Isle of Rhum II. The causes of the debris

    Microsoft Academic Search

    John Henry H. Looney; John Proctor

    1989-01-01

    The relationship between the Rhum ultrabasic skeletal soils and their debris vegetation was investigated by plant analyses and field and laboratory experiments. Samples of Agrostis vinealis, Arenaria norvegica ssp norvegica, Calluna vulgaris, Festuca vivipara, Plantago maritima and Racomitrium lanuginosum from these soils usually had low concentrations of potassium and calcium, and high concentrations of sodium, magnesium (and high Mg\\/Ca quotients),

  1. Evolution of soil moisture spatial structure in a mixed vegetation pixel during the Southern Great Plains

    E-print Network

    Mohanty, Binayak P.

    . S. Famiglietti Department of Geological Sciences, University of Texas at Austin, Austin, Texas T. H will be useful for assessing remotely sensed soil moisture data collected during the SGP97 Hydrology Experiment in mixed vegetation pixels. 1. Introduction Surface soil moisture plays a pivotal role in the global water

  2. MANAGING VEGETABLE GARDEN SOIL FERTILITY IN VERMONT Vern Grubinger, Extension Professor, University of Vermont

    E-print Network

    Hayden, Nancy J.

    be provided from fertilizers, but only after the contribution of compost, manure, cover crops and soil organic moss. #12;2 Compost and manures contain N, P, K and small amounts of micronutrients. On low fertility1 MANAGING VEGETABLE GARDEN SOIL FERTILITY IN VERMONT Vern Grubinger, Extension Professor

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

    Microsoft Academic Search

    Esteban G. Jobbagy; Robert B. Jackson

    2000-01-01

    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

  4. Predicting soil moisture and wheat vegetative growth from ERTS-1 imagery. M.S. Thesis; [Kansas

    NASA Technical Reports Server (NTRS)

    Krupp, J. W.

    1974-01-01

    The author has identified the following significant results. Study results indicate: (1) Vegetative growth was best predicted by a linear relationship between leaf area index and the radio of band 4 to band 5. All significant soil moisture effects were cancelled by the ratio. (2) Soil moisture at a depth of 0 to 15 cm, with specific soil factors, was predicted by band 4 and leaf area index with a high regression coefficient. (3) Vegetative growth, measured by leaf area index, was one of the necessary inputs in evaluating the winter wheat crop coefficient from March to maturity.

  5. Comparisons among a new soil index and other two- and four-dimensional vegetation indices

    NASA Technical Reports Server (NTRS)

    Wiegand, C. L.; Richardson, A. J.

    1982-01-01

    The 2-D difference vegetation index (DVI) and perpendicular vegetation index (PVI), and the 4-D green vegetation index (GVI) are compared in Landsat MSS data from grain sorghum (Sorghum bicolor, L. Moench) fields for the years 1973 to 1977. PVI and DVI were more closely related to LAI than was GVI. A new 2-D soil line index (SLI), the vector distance from the soil line origin to the point of intersection of PVI with the soil line, is defined and compared with the 4-D soil brightness index, SBI. SLI (based on MSS and MSS7) and SL16 (based on MSS5 and MSS6) were smaller in magnitude than SBI but contained similar information about the soil background. These findings indicate that vegetation and soil indices calculated from the single visible and reflective infrared band sensor systems, such as the AVHRR of the TIROS-N polar orbiting series of satellites, will be meaningful for synoptic monitoring of renewable vegetation. Previously announced in STAR as N83-14567

  6. Comparisons among a new soil index and other two- and four-dimensional vegetation indices

    NASA Technical Reports Server (NTRS)

    Wiegand, C. L.; Richardson, A. J. (principal investigators)

    1982-01-01

    The 2-D difference vegetation index (DVI) and perpendicular vegetation index (PVI), and the 4-D green vegetation index (GVI) are compared in LANDSAT MSS data from grain sorghum (Sorghum bicolor, L. Moench) fields for the years 1973 to 1977. PVI and DVI were more closely related to LAI than was GVI. A new 2-D soil line index (SLI), the vector distance from the soil line origin to the point of intersection of PVI with the soil line, is defined and compared with the 4-D soil brightness index, SBI. SLI (based on MSS and MSS7) and SL16 (based on MSS 5 and MSS 6) were smaller in magnitude than SBI but contained similar information about the soil background. These findings indicate that vegetation and soil indices calculated from the single visible and reflective infrared band sensor systems, such as the AVHRR of the TIROS-N polar orbiting series of satellites, will be meaningful for synoptic monitoring of renewable vegetation.

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

    PubMed Central

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

    2013-01-01

    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

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

    Microsoft Academic Search

    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

    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

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

    Microsoft Academic Search

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

    2011-01-01

    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

  10. Can artificial soil be used in the vegetative vigor test for U.S. pesticide registration?

    PubMed

    Bidelspach, Conor; Olszyk, David; Pfleeger, Thomas

    2008-10-01

    Current testing guidelines for pesticide registration for the protection of nontarget plants calls for the use of sterilized, standardized soil consisting of primarily sandy loam, loamy sand, loamy clay, or clay loam that contains up to 3% organic matter. Low organic matter soils can be difficult to manage in a greenhouse setting because when soils dry, they contract, causing impeded water infiltration, or when overwatered, poor drainage increases the chances of anaerobic conditions. The purpose of this study was to determine if the results for the vegetative vigor test differed when using either natural or artificial soils. The herbicide sulfometuron methyl was applied 14 d after emergence at 0.1 and 0.0032 of the suggested field application rate. Six plant species were tested, 4 of the common test species, Zea mays (corn), Glycine max (soybean), Avena sativa (oat), and Lactuca sativa (lettuce), and 2 native plants of the Willamette Valley, Oregon prairie, Bromus carinatus (California brome) and Ranunculus occidentalis (western buttercup). Herbicide application rate was the most significant factor in the experiment regardless of soil type. The different soils generally produced different results, even though the 2 native soils, one from Oregon and the other from Maryland, are both acceptable soils for the pesticide registration tests. The plants grown on artificial soil produced results generally between the Oregon and Maryland soil results. This study indicates that artificial soils may produce results similar to or more sensitive than soils currently used in the vegetative vigor test. PMID:18563958

  11. Carbon in the Vegetation and Soils of Great Britain

    Microsoft Academic Search

    R. Milne; T. A. Brown

    1997-01-01

    •The total amount of carbon held by vegetation in Great Britain is estimated to be 114 Mtonnes. •Woodlands and forests hold 80% of the G.B. total although they occupy only about 11% of the rural land area. Broadleaf species hold about 50% of the carbon in woodlands and forests. •A map of carbon in the vegetation of Great Britain at

  12. Influence of soil spatial variability on surface and subsurface flow at a vegetative buffer strip scale.

    NASA Astrophysics Data System (ADS)

    Gatel, Laura; Lauvernet, Claire; Carluer, Nadia; Paniconi, Claudio; Leblois, Etienne

    2015-04-01

    The objective of this study is to evaluate the influence of soil hydrodynamic characteristics variability on surface and subsurface flow at a vegetative buffer strip scale, using mecanistic modeling. Cathy (CATchment HYdrology, Camporese et al. 2010) is a research physically based model able to simulate coupled surface/subsurface flow. The evaluation of soil hydrodynamic characteristics variability is based essentially on saturated hydraulic conductivity because of its large spatial variability in the 3 dimensions and its important influence on flow pathways, as well as its high influence on the model output variables. After testing the model sensitivity to some input variables, to the boundary conditions and to the mesh definition, the work focuses on hydraulic conductivity parametrization. The study was first conducted with uniform (by horizons) conductivity domains based on field measurements. In a second step, heterogeneous fields were generated by a statistical tool which allows the user to choose the statistical law (in this case, lognormal or Gauss), the hydraulic conductivity auto-correlation length and the possibility to condition the fields with measured points. With all these different ways to represent spatial variability of hydraulic conductivity, model simulated surface and subsurface fluxes consistent with datasets from artificial run-off experiments on an French wineyard hillslope (Morcille catchment, Beaujolais, France). Model simulations are evaluated and compared to observations on several criteria : consistency, stability, interaction with water table, etc...

  13. Effect of vegetation on rock and soil type discrimination

    NASA Technical Reports Server (NTRS)

    Siegal, B. S.; Goetz, A. F. H.

    1977-01-01

    The effect of naturally occurring vegetation on the spectral reflectance of earth materials in the wavelength region of 0.45 to 2.4 microns is determined by computer averaging of in situ acquired spectral data. The amount and type of vegetation and the spectral reflectance of the ground are considered. Low albedo materials may be altered beyond recognition with only ten per cent green vegetation cover. Dead or dry vegetation does not greatly alter the shape of the spectral reflectance curve and only changes the albedo with minimum wavelength dependency. With increasing amounts of vegetation the Landsat MSS band ratios 4/6, 4/7, 5/6, and 5/7 are significantly decreased whereas MSS ratios 4/5 and 6/7 remain entirely constant.

  14. Integrated field lysimetry and porewater sampling for evaluation of chemical mobility in soils and established vegetation.

    PubMed

    Matteson, Audrey R; Mahoney, Denis J; Gannon, Travis W; Polizzotto, Matthew L

    2014-01-01

    Potentially toxic chemicals are routinely applied to land to meet growing demands on waste management and food production, but the fate of these chemicals is often not well understood. Here we demonstrate an integrated field lysimetry and porewater sampling method for evaluating the mobility of chemicals applied to soils and established vegetation. Lysimeters, open columns made of metal or plastic, are driven into bareground or vegetated soils. Porewater samplers, which are commercially available and use vacuum to collect percolating soil water, are installed at predetermined depths within the lysimeters. At prearranged times following chemical application to experimental plots, porewater is collected, and lysimeters, containing soil and vegetation, are exhumed. By analyzing chemical concentrations in the lysimeter soil, vegetation, and porewater, downward leaching rates, soil retention capacities, and plant uptake for the chemical of interest may be quantified. Because field lysimetry and porewater sampling are conducted under natural environmental conditions and with minimal soil disturbance, derived results project real-case scenarios and provide valuable information for chemical management. As chemicals are increasingly applied to land worldwide, the described techniques may be utilized to determine whether applied chemicals pose adverse effects to human health or the environment. PMID:25045915

  15. Soil moisture inferences from thermal infrared measurements of vegetation temperatures

    NASA Technical Reports Server (NTRS)

    Jackson, R. D. (principal investigator)

    1981-01-01

    Thermal infrared measurements of wheat (Triticum durum) canopy temperatures were used in a crop water stress index to infer root zone soil moisture. Results indicated that one time plant temperature measurement cannot produce precise estimates of root zone soil moisture due to complicating plant factors. Plant temperature measurements do yield useful qualitative information concerning soil moisture and plant condition.

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

    PubMed

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

    2011-09-01

    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

  17. Heavy metal load of soil, water and vegetables in peri-urban Delhi.

    PubMed

    Singh, S; Kumar, M

    2006-09-01

    Peri-urban lands are often used for production of vegetables for better market accessibility and higher prices. But most of these lands are contaminated with heavy metals through industrial effluents, sewage and sludge, and vehicular emission. Vegetables grown in such lands, therefore, are likely to be contaminated with heavy metals and unsafe for consumption. Samples of vegetables i.e., spinach (Spinacia oleracea L.) and okra (Abelmoschus esculentus L.); soil and irrigation water were collected from 5 peri-urban sites of New Delhi to monitor their heavy metal loads. While heavy metal load of the soils were below the maximum allowable limit prescribed by the World Health Organization (WHO), it was higher in irrigation water and vegetable samples. The spinach and okra samples showed Zn, Pb and Cd levels higher than the WHO limits. The levels of Cu, however, were at their safe limits. Metal contamination was higher in spinach than in okra. Spatial variability of metal contamination was also observed in the study. Bio-availability of metals present in soil showed a positive relationship with their total content and organic matter content of soil but no relationship was observed with soil pH. Washing of vegetables with clean water was a very effective and easy way of decontaminating the metal pollution as it reduced the contamination by 75 to 100%. PMID:16897527

  18. Ad Hoc Modeling of Root Zone Soil Water with Landsat Imagery and Terrain and Soils Data

    PubMed Central

    Sankey, Joel B.; Lawrence, Rick L.; Wraith, Jon M.

    2008-01-01

    Agricultural producers require knowledge of soil water at plant rooting depths, while many remote sensing studies have focused on surface soil water or mechanistic models that are not easily parameterized. We developed site-specific empirical models to predict spring soil water content for two Montana ranches. Calibration data sample sizes were based on the estimated variability of soil water and the desired level of precision for the soil water estimates. Models used Landsat imagery, a digital elevation model, and a soil survey as predictor variables. Our objectives were to see whether soil water could be predicted accurately with easily obtainable calibration data and predictor variables and to consider the relative influence of the three sources of predictor variables. Independent validation showed that multiple regression models predicted soil water with average error (RMSD) within 0.04 mass water content. This was similar to the accuracy expected based on a statistical power test based on our sample size (n = 41 and n = 50). Improved prediction precision could be achieved with additional calibration samples, and range managers can readily balance the desired level of precision with the amount of effort to collect calibration data. Spring soil water prediction effectively utilized a combination of land surface imagery, terrain data, and subsurface soil characterization data. Ranchers could use accurate spring soil water content predictions to set stocking rates. Such management can help ensure that water, soil, and vegetation resources are used conservatively in irrigated and non-irrigated rangeland systems.

  19. Effects of vegetation cover on the microwave radiometric sensitivity to soil moisture

    NASA Technical Reports Server (NTRS)

    Ulaby, F. T.; Dobson, M. C.; Razani, M.

    1983-01-01

    The reduction in sensitivity of the microwave brightness temperature to soil moisture content due to vegetation cover is analyzed using airborne observations made at 1.4 and 5 GHz. The data were acquired during six flights in 1978 over a test site near Colby, Kansas. The test site consisted of bare soil, wheat stubble, and fully mature corn fields. The results for corn indicate that the radiometric sensitivity to soil moisture S decreases in magnitude with increasing frequency and with increasing angle of incidence (relative to nadir). The sensitivity reduction factor, defined in terms of the radiometric sensitivities for bare soil and canopy-covered conditions Y = 1 - Scan/Ss was found to be equal to 0.65 for normal incidence at 1.4 GHz, and increases to 0.89 at 5 GHz. These results confirm previous conclusions that the presence of vegetation cover may pose a serious problem for soil moisture detection with passive microwave sensors.

  20. 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...

  1. Soil and water components of banded vegetation patterns

    Microsoft Academic Search

    C Valentin; J. M d'Herbès; J Poesen

    1999-01-01

    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

  2. [Relationships between typical vegetations, soil salinity, and groundwater depth in the Yellow River Delta of China].

    PubMed

    Ma, Yu-Lei; Wang, De; Liu, Jun-Min; Wen, Xiao-Hu; Gao, Meng; Shao, Hong-Bo

    2013-09-01

    Soil salinity and groundwater depth are the two important factors affecting the vegetation growth and distribution in the Yellow River Delta. Through field investigation and statistical analysis, this paper studied the relationships between the typical vegetations (Suaeda heteroptera-Tamarix chinensis, Robinia pseudoacacia, Phragmites australis, and cotton) , soil salinity, and groundwater depth in the Delta. In the study area, groundwater depth had significant effects on soil salinity, with the average influence coefficient being 0.327. When the groundwater depth was 0.5-1.5 m, soil salinization was most severe. The vegetation growth in the Delta was poorer, with the NDVI in 78% of the total area being less than 0.4. Groundwater depth and soil salinity had significant effects on the vegetation distribution. Soil salinity had significant effects on the NDVI of R. pseudoacacia, S. heteroptera-T. chinensis, P. australis, and cotton, while groundwater depth had significant effects on the NDVI of S. heteroptera - T. chinensis, but lesser effects on the NDVI of P. australis, cotton and R. pseudoacacia. PMID:24417097

  3. Evolution of vegetation and soil nutrients after uranium mining in Los Ratones mine (Cáceres, Spain).

    PubMed

    Pérez-Fernández, María A; Vera-Tomé, Feliciano; Blanco-Rodríguez, María P; Lozano, Juan C

    2014-06-01

    The evolution of vegetation structure following mine rehabilitation is rather scarce in the literature. The concentration of long-lived radionuclides of the (238)U series might have harmful effects on living organisms. We studied soil properties and the natural vegetation occurring along a gradient in Los Ratones, an area rehabilitated after uranium mining located in Cáceres, Spain. Soil and vegetation were sampled seasonally and physical and chemical properties of soil were analysed, including natural isotopes of (238)U, (230)Th, (226)Ra and (210)Pb. Species richness, diversity, evenness and plant cover were estimated and correlated in relation to soil physical and chemical variables. The location of the sampling sites along a gradient had a strong explanatory effect on the herbaceous species, as well as the presence of shrubs and trees. Seasonal effects of the four natural isotopes were observed in species richness, species diversity and plant cover; these effects were directly related to the pH values in the soil, this being the soil property that most influences the plant distribution. Vegetation in the studied area resembles that of the surroundings, thus proving that the rehabilitation carried out in Los Ratones mine was successful in terms of understorey cover recovery. PMID:24450758

  4. Probabilistic Evaluation of Anthropogenic Regulations In a Vegetated River Channel Using a Vegetation Dynamics Modeling

    NASA Astrophysics Data System (ADS)

    Miyamoto, Hitoshi

    2015-04-01

    Vegetation overgrowth in fluvial floodplains, gravel beds, and sand bars has been a serious engineering problem for riparian management in Japan. From the viewpoints of flood control and ecological conservation, it would be necessary to predict the vegetation dynamics accurately for long-term duration. In this research, we have developed a stochastic model for predicting the vegetation dynamics in fluvial floodplains with emphasis on the interaction with flood impacts. The model consists of the following four components: (i) long-term stochastic behavior of flow discharge, (ii) hydrodynamics in a channel with floodplain vegetation, (iii) variation of riverbed topography, and (iv) vegetation dynamics on floodplains. In the vegetation dynamics model, the flood discharge (i) is stochastically simulated using a filtered Poisson process, one of the conventional approaches in hydrological time-series generation. The component for vegetation dynamics (iv) includes the effects of tree growth, mortality by floods, and infant tree recruitment. Vegetation condition has been observed mainly before and after floods since 2008 at a field site located between 23-24 km from the river mouth in Kako River, Japan. The Kako River has the catchment area of 1,730 km2 and the main channel length of 96 km. This site is one of the vegetation overgrowth sites in the Kako River floodplains. The predominant tree species are willows and bamboos. In the field survey, the position, trunk diameter and height of each tree as well as the riverbed materials were measured after several flood events to investigate their impacts on the floodplain vegetation community. This presentation tries to examine effects of anthropogenic river regulations, i.e., thinning and cutting-down, in the vegetated channel in Kako River by using the vegetation dynamics model. Sensitivity of both the flood water level and the vegetation status in the channel is statistically evaluated in terms of the different cutting-down levels, timings and scales of the thinning, etc., by the Monte Carlo simulation of the model.

  5. Monitoring soil-vegetation interactions using non-invasive geophysical techniques

    NASA Astrophysics Data System (ADS)

    Perri, M.; Cassiani, G.; Boaga, J.; Rossi, M.; Vignoli, G.; Deiana, R.; Ursino, N.; Putti, M.; Majone, B.; Bellin, A.; Blaschek, M.; Duttmann, R.; Meyer, S.; Ludwig, R.; Soddu, A.; Dietrich, P.; Werban, U.

    2012-12-01

    The understanding of soil-vegetation-atmosphere interactions is of utmost importance in the solution of a number of hydrological questions and practical issues, including flood control, agricultural best practice, slope stability and impacts of climatic changes. Geophysical time-lapse monitoring can greatly contribute to the understanding of these interactions particularly for its capability to map in space and time the effects of vegetation on soil moisture content. In this work we present the results of two case studies showing the potential of hydro-geophysics in this context. The first example refers to the long term monitoring of the soil static and dynamic characteristics in an experimental site located in Sardinia (Italy). The main objective of this study is to understand the effects of soil - water - plants interactions on soil water balance. A combination of time-lapse electromagnetic induction (EMI) monitoring over wide areas and localized irrigation tests monitored by electrical resistivity tomography (ERT) and TDR soil moisture measurements is here used, in order to achieve quantitative field-scale estimates of moisture content from topsoil layer. Natural gamma-ray emission mapping, texture analysis and laboratory calibration of an electrical constitutive relationship on soil samples complete the dataset. We therefore observed that the growth of vegetation, with the associated below ground allocation of biomass, has a significant impact on the soil moisture dynamics. In particular vegetation extracts a large amount of water from the soil in the hot season, but it also reduces evaporation by shadowing the soil surface. In addition, vegetation enhances the soil wetting process as the root system facilitates water infiltration, thus creating a positive feedback system. The second example regards the time-lapse monitoring of soil moisture content in an apple orchard located in the Alpine region of Northern Italy (Trento). A three-dimensional cross-hole ERT setup was created using four small-scale boreholes and a 2D array of surface electrodes. The soil response to irrigation and evapo-transpiration evidences the location of tree roots, including the influence of irrigation patterns on the root growth, and their efficiency at removing soil moisture.

  6. Duration and frequency of water stress in vegetation: An analytical model

    NASA Astrophysics Data System (ADS)

    Ridolfi, L.; D'Odorico, P.; Porporato, A.; Rodriguez-Iturbe, I.

    2000-08-01

    In the study of the evolutionary dynamics of soil moisture at a site, it is particularly important to define some characteristic properties of the temporal structure of the periods in which the soil water content is below certain levels indicative of water stress conditions in vegetation. The analysis of such properties provides an approach to establish some hydrologic basis for the understanding and modeling of ecosystems functioning in water-limited environments. This paper deals with a stochastic point process model of soil water balance. Expressions for both the mean number and the mean duration of time intervals during which the soil moisture is below a given threshold are analytically derived as a function of climate, soil, and vegetation. The seasonal mean value of water deficit is also analytically obtained. These properties are used to characterize the state of water stress in plants and to study its dependence on the interrelated dynamics. Estimates are included for the probability distributions of the frequency and duration of the stress and soil water deficit, for different hypotheses on climate, soil, and vegetation. Both the hydrologic and the ecologic implications of the results are briefly outlined.

  7. [Spatial variation of soil moisture/salinity and the relationship with vegetation under natural conditions in Yancheng coastal wetland].

    PubMed

    Zhang, Hua-Bing; Liu, Hong-Yu; Li, Yu-Feng; An, Jing; Xue, Xing-Yu; Hou, Ming-Hang

    2013-02-01

    Taking the core part of Yancheng national nature reserve as the study area, according to soil sampling analysis of coastal wetlands in April and May 2011 land the 2011 ETM + remote sensing image, the spatial difference characteristic of coastal wetlands soil moisture and salinity, and the relationship with vegetation under natural conditions, were investigated with the model of correspondence analysis (CCA), linear regression simulation and geo-statistical method. The results showed: Firstly, the average level of the soil moisture was fluctuating between 36.820% and 46.333% , and the soil salinity was between 0.347% and 1.328% , in a more detailed sense, the Spartina swamp was the highest, followed by the mudflats swamp, the Suaeda salsa swamp, and the Reed marsh. Secondly, the spatial variation of soil moisture was consistent with that of the salinity, and the degree of variation in the east-west direction was greater than that in the north-south. The maximum soil moisture and salinity were found in the southwest Spartina swamp. The minimum was in the Reed swamp. The soil moisture and salinity were divided into 5 levels, from I to V. Level IV occupied the highest proportion, which were 36.156% and 28.531% , respectively. Finally, different landscape types with the combination of soil moisture and salinity showed a common feature that the moisture and salinity were from both high to low. The soil moisture value of Reed marshes was lower than 40.116% and the salinity value was lower than 0. 676% . The soil moisture value of Suaeda salsa marshes was between 38. 162% and 46. 403% and the salinity value was between 0.417% and 1.295%. The soil moisture value of Spartina swamp was higher than 43.214% and the salinity was higher than 1.090%. The soil moisture value of beach was higher than 43.214% and the salinity was higher than 0.677%. PMID:23668120

  8. Does vegetation type matter? Plant-soil interactions change urban rain garden hydrology

    NASA Astrophysics Data System (ADS)

    Johnston, M. R.; Balster, N. J.

    2009-12-01

    Residential infiltration basins or rain gardens are being installed at an ever-increasing rate across the urban landscape, yet their impact on the urban hydrologic cycle remains largely untested. Specifically, because rain garden design varies considerably, we know little about how plant-soil dynamics control their hydrologic function. In a controlled field experiment with closed-system rain gardens, we tested the hydrologic response of three vegetation treatments common in rain garden design (shrubs, wet-mesic prairie, turfgrass). We used a complete, randomized block design in which each vegetative treatment was replicated three times. Each rain garden represented 17% of a contributing roof area where stormwater was collected and then applied following precipitation events. We continuously monitored stormwater input, soil water content, and soil exfiltration to assess differences in the hydrologic function of each rain garden. Overall, vegetation type significantly changed the magnitude and timing of the hydrologic response. During the months of June and July, 2009, the rain gardens planted with shrubs, prairie, and turfgrass all reduced the volume of soil exfiltration by 50%, 30%, and 17%, respectively, relative to the non-vegetated controls. Similarly, depending on storm magnitude and antecedent soil moisture, vegetation type significantly decreased the mean peak flow rate of exfiltration (p < 0.001), as well as the duration of the exfiltration response (p < 0.0001). The flashiest hydrologic responses (i.e. shortest lag time, highest peak flow rate) were observed in the turfgrass gardens. We explain these vegetative-mediated responses in hydrology relative to differences in infiltration, aboveground dry mass, root dynamics, and transpirative loss. Our data suggest that changing the vegetation type of urban rain gardens yields marked differences in the hydrologic budget via shifts in ecohydrological processes.

  9. Coincidence and spatial variability of geology, soils, and vegetation, Mill Run watershed, Virginia.

    USGS Publications Warehouse

    Olson, C.G.; Hupp, C.R.

    1986-01-01

    The Mill Run watershed is a structurally-controlled synclinal basin on the eastern limb of the Massanutten Mountain complex of NW Virginia. Bedrock contacts are obscured by coarse sandstone debris from exposures near basin divides. Colluvium blankets more than half the basin, masking geomorphic surfaces, affecting vegetation patterns, and contributing to the convexity of the alluvial, terrace, pediment and erosion surfaces. Vegetation is strongly interdependent with geomorphology, bedrock geology, and soils. - from Authors

  10. The effect of vegetation on soil redox within a seasonally flooded forested system

    Microsoft Academic Search

    Kirk J. Havens

    1997-01-01

    The effect of rhizosphere oxidation on redox level was investigated between vegetated and denuded plots and betweenAcer rubrum andFraxinus pennsylvanica seedlings within a seasonally flooded forested system in Virginia. Redox potentials were significantly greater (p<0.05) in\\u000a the upper 15 cm of the soils in the vegetated plots. Redox potential within the root mass ofAcer rubrum seedlings did not differ significantly

  11. Microbial properties of rhizosphere soils as affected by rotation, grafting, and soil sterilization in intensive vegetable production systems

    Microsoft Academic Search

    Yongqiang Tian; Xueyan Zhang; Jun Liu; Qing Chen; Lihong Gao

    2009-01-01

    The increased use of rotation, grafting, and soil sterilization has been documented to increase crop yield in intensive vegetable production systems in China. It is believed that these practices can promote changes in the rhizosphere that enhance early growth of plants. A 2-year greenhouse experiment on tomato double-cropping systems was conducted to investigate the effects of different agricultural treatments on

  12. Relations between soil moisture and satellite vegetation indices in the U.S. Corn Belt

    USGS Publications Warehouse

    Adegoke, J.O.; Carleton, A.M.

    2002-01-01

    Satellite-derived vegetation indices extracted over locations representative of midwestern U.S. cropland and forest for the period 1990-94 are analyzed to determine the sensitivity of the indices to neutron probe soil moisture measurements of the Illinois Climate Network (ICN). The deseasoned (i.e., departures from multiyear mean annual cycle) soil moisture measurements are shown to be weakly correlated with the deseasoned full resolution (1 km ?? 1 km) normalized difference vegetation index (NDVI) and fractional vegetation cover (FVC) data over both land cover types. The association, measured by the Pearson-moment-correlation coefficient, is stronger over forest than over cropland during the growing season (April-September). The correlations improve successively when the NDVI and FVC pixel data are aggregated to 3 km ?? 3 km, 5 km ?? 5 km, and 7 km ?? 7 km areas. The improved correlations are partly explained by the reduction in satellite navigation errors as spatial aggregation occurs, as well as the apparent scale dependence of the NDVI-soil moisture association. Similarly, stronger relations are obtained with soil moisture data that are lagged by up to 8 weeks with respect to the vegetation indices, implying that soil moisture may be a useful predictor of warm season satellite-derived vegetation conditions. This study suggests that a "long-term" memory of several weeks is present in the near-surface hydrological characteristics, especially soil water content, of the Midwest Corn Belt. The memory is integrated into the satellite vegetation indices and may be us??eful for predicting crop yield estimates and surface temperature anomalies.

  13. Magnetic response of soils and vegetation to heavy metal pollution--a case study.

    PubMed

    Jordanova, Neli V; Jordanova, Diana V; Veneva, Ludmila; Yorova, Kitka; Petrovsky, Eduard

    2003-10-01

    Fast and cost-effective detection of industrial pollution can significantly promote its ecological, economic, and social assessment. A magnetometric method, used for qualitative determination of anthropogenic contamination, meets these requirements but needs further development in more quantitative terms. It could be used successfully in numerous cases when the heavy metals coexist with strongly magnetic iron oxide particles in the source dust. We present an integrated magnetic and geochemical study that examines the utility of magnetometric techniques for rapid, qualitative detection of metallic pollutants in soils and vegetation. The new aspect of our approach, in comparison with previously published articles on this subject, is the combined investigation (magnetic and geochemical) of both soils and vegetation, thus using an additional medium for employing the magnetometry as a pollution proxy at a site. The study area is a small (approximately 3 km2) region in the suburbs of Sofia (Bulgaria), with the main pollution source being a metallurgical factory. Soil samples have been taken from the topmost 20 cm from private gardens, located at different distances from the factory. Vegetation samples were taken from ryegrass (both leaves and roots) and leaves from two kinds of deciduous trees (maple and acacia). The results show that both vegetation and soils are characterized by enhanced magnetic properties, compared to background material, which is due to the presence of magnetite particles of anthropogenic origin accompanying heavy metal emissions. SEM images and microprobe analyses reveal the presence of a significant amount of particles, containing heavy metals (including iron) in vegetation samples taken close to the main pollution source. Correlation analyses show a statistically significant link (correlation coefficients ranging from 0.6 to 0.7) between magnetic susceptibility and the main heavy metals (Cu, Zn, Pb) in soil samples, indicating that the magnetic susceptibility can provide a proxy method for identifying the relative contribution of industrial pollution in soils and vegetation, that is reliable, inexpensive, and less time-consuming than standard chemical analyses. PMID:14572094

  14. Post Chernobyl surveys of radiocaesium in soil, vegetation, wildlife and fungi in Great Britain

    NASA Astrophysics Data System (ADS)

    Chaplow, J. S.; Beresford, N. A.; Barnett, C. L.

    2014-12-01

    The dataset "Post Chernobyl surveys of radiocaesium in soil, vegetation, wildlife and fungi in Great Britain" was developed to enable data collected by the Natural Environment Research Council after the Chernobyl accident to be made publicly available. Data for samples collected between May 1986 (immediately after Chernobyl) to spring 1997 are presented. Additional data to radiocaesium concentrations are presented where available. The data have value in trying to assess the contribution of new sources of radiocaesium in the environment, providing baseline data for future planned releases and to aid the development and testing of models. The data are freely available for non-commercial use under Open Government Licence terms and conditions. doi:10.5285/7a5cfd3e-0247-4228-873d-5be563c4ee3b

  15. Physically-based parameterization of spatially variable soil and vegetation using satellite multispectral data

    NASA Technical Reports Server (NTRS)

    Jasinski, Michael F.; Eagleson, Peter S.

    1989-01-01

    A stochastic-geometric landsurface reflectance model is formulated and tested for the parameterization of spatially variable vegetation and soil at subpixel scales using satellite multispectral images without ground truth. Landscapes are conceptualized as 3-D Lambertian reflecting surfaces consisting of plant canopies, represented by solid geometric figures, superposed on a flat soil background. A computer simulation program is developed to investigate image characteristics at various spatial aggregations representative of satellite observational scales, or pixels. The evolution of the shape and structure of the red-infrared space, or scattergram, of typical semivegetated scenes is investigated by sequentially introducing model variables into the simulation. The analytical moments of the total pixel reflectance, including the mean, variance, spatial covariance, and cross-spectral covariance, are derived in terms of the moments of the individual fractional cover and reflectance components. The moments are applied to the solution of the inverse problem: The estimation of subpixel landscape properties on a pixel-by-pixel basis, given only one multispectral image and limited assumptions on the structure of the landscape. The landsurface reflectance model and inversion technique are tested using actual aerial radiometric data collected over regularly spaced pecan trees, and using both aerial and LANDSAT Thematic Mapper data obtained over discontinuous, randomly spaced conifer canopies in a natural forested watershed. Different amounts of solar backscattered diffuse radiation are assumed and the sensitivity of the estimated landsurface parameters to those amounts is examined.

  16. Occurrence and importance of anaerobic ammonium-oxidising bacteria in vegetable soils.

    PubMed

    Shen, Li-Dong; Wu, Hong-Sheng; Gao, Zhi-Qiu; Xu, Xiang-Hua; Chen, Tie-Xi; Liu, Shuai; Cheng, Hai-Xiang

    2015-07-01

    The quantitative importance of anaerobic ammonium oxidation (anammox) has been described in paddy fields, while the presence and importance of anammox in subsurface soil from vegetable fields have not been determined yet. Here, we investigated the occurrence and activity of anammox bacteria in five different types of vegetable fields located in Jiangsu Province, China. Stable isotope experiments confirmed the anammox activity in the examined soils, with the potential rates of 2.1 and 23.2 nmol N2?g(-1) dry soil day(-1), and the anammox accounted for 5.9-20.5 % of total soil dinitrogen gas production. It is estimated that a total loss of 7.1-78.2 g N m(-2) year(-1) could be linked to the anammox process in the examined vegetable fields. Phylogenetic analyses showed that multiple co-occurring anammox genera were present in the examined soils, including Candidatus Brocadia, Candidatus Kuenenia, Candidatus Anammoxoglobus and Candidatus Jettenia, and Candidatus Brocadia appeared to be the most common anammox genus. Quantitative PCR further confirmed the presence of anammox bacteria in the examined soils, with the abundance varying from 2.8?×?10(5) to 3.0?×?10(6) copies g(-1) dry soil. Correlation analyses suggested that the soil ammonium concentration had significant influence on the activity and abundance of anammox bacteria in the examined soils. The results of our study showed the presence of diverse anammox bacteria and indicated that the anammox process could serve as an important nitrogen loss pathway in vegetable fields. PMID:25690313

  17. The Soil Biota Composition along a Progressive Succession of Secondary Vegetation in a Karst Area

    PubMed Central

    He, Xunyang; Liu, Lu; Wang, Kelin

    2014-01-01

    Karst ecosystems are fragile and are in many regions degraded by anthropogenic activities. Current management of degraded karst areas focuses on aboveground vegetation succession or recovery and aims at establishing a forest ecosystem. Whether progressive succession of vegetation in karst areas is accompanied by establishment of soil biota is poorly understood. In the present study, soil microbial and nematode communities, as well as soil physico-chemical properties were studied along a progressive succession of secondary vegetation (from grassland to shrubland to forest) in a karst area in southwest China. Microbial biomass, nematode density, ratio of fungal to bacterial biomass, nematode structure index, and nematode enrichment index decreased with the secondary succession in the plant community. Overall, the results indicated a pattern of declines in soil biota abundance and food web complexity that was associated with a decrease in soil pH and a decrease in soil organic carbon content with the progressive secondary succession of the plant community. Our findings suggest that soil biota amendment is necessary during karst ecosystem restoration and establishment and management of grasslands may be feasible in karst areas. PMID:25379741

  18. [Sizes of soil macropores and related main affecting factors on a vegetated basalt slope].

    PubMed

    Guan, Qi; Xu, Ze-Min; Tian, Lin

    2013-10-01

    The landslide on vegetated slopes caused by extreme weather has being increased steadily, and the preferential flow in soil macropores plays an important role in the landslide. By using water breakthrough curve and Poiseuille equation, this paper estimated the radius range, amount, and average volume of soil macropores on a vegetated basalt slope of Maka Mountain, Southwest China, and analyzed the distribution of the soil macropores and the main affecting factors. In the study area, the radius of soil macropores ranged from 0.3 to 1.8 mm, mainly between 0.5 and 1.2 mm. The large-radius macropores (1.4-1.8 mm) were lesser, while the small-radius macropores (< 1.4 mm) were more. With the development of soil profile, soil macropores were more in upper layers and lesser in deeper layers. The average volume of the macropores contributed 84.7% to the variance of steady effluent rate. Among the factors affecting the average volume of the large macropores, vegetations root mass had a linear relationship, with the correlation coefficient being 0.70, and soil organic matter content also had a linear relationship, with the correlation coefficient being 0.64. PMID:24483084

  19. Technique for assessing vegetation-induced moisture flux, with implications for global climate modeling

    NASA Technical Reports Server (NTRS)

    Macari, Emir Jose

    1990-01-01

    The time between storms, the duration of storms, and the storm depths are studied in relation to vegetation controls on the disposition of rainfall. It is proposed that understanding the movement of water between the vegetation and soil (including evapotranspiration and infiltration) will be the gateway for modeling atmospheric flux and improving global climate models. The overall objective goal of the proposed research effort is to develop a field/lab methodology which will provide a better understanding of vegetation induced water movement. Water flow initiated from stem flow of wooded slopes feeds soil water pathways, which in turn feed the deeper ground water system and give rise to stream response. This is balanced by more water inputs via throughfall, where it percolates the soil matrix and allows much greater rates of evapotranspiration and atmospheric/soil moisture flux. This research study seeks to gain an understanding of the effect of vegetation on soil moisture, and the effect of this differential wetting on resulting evapotranspiration and atmospheric flux.

  20. Agricultural use of soil, consequences in soil organic matter and hydraulic conductivity compared with natural vegetation in central Spain

    NASA Astrophysics Data System (ADS)

    Vega, Verónica; Carral, Pilar; Alvarez, Ana Maria; Marques, Maria Jose

    2014-05-01

    When ecosystems are under pressure due to high temperatures and water scarcity, the use of land for agriculture can be a handicap for soil and water conservation. The interactions between plants and soils are site-specific. This study provides information about the influence of the preence vs. The absence of vegetation on soil in a semi-arid area of the sout-east of Madrid (Spain, in the Tagus River basin. In this area soil materials are developed over a calcareous-evaporitic lithology. Soils can be classified as Calcisols, having horizons of accumulation with powdered limestone and irregular nodules of calcium carbonate. They can be defined as Haplic Cambisols and Leptic Calcisols (WRB 2006-FAO). The area is mainly used for rainfed agriculture, olive groves, vineyards and cereals. There are some patches of bushes (Quercus sp.) and grasses (Stipa tenacissima L.) although only found on the top of the hills. This study analyses the differences found in soils having three different covers: Quercus coccifera, Stipa tenacissima and lack of vegetation. This last condition was found in the areas between cultivated olive trees. Soil organic matter, porosity and hydraulic conductivity are key properties of soil to understand its ability to adapt to climate or land use changes. In order to measure the influence of different soil covers, four replicates of soil were sampled in each condition at two soil depth, (0-10 cm and 10-20 cm). Hydraulic conductivity was measured in each soil condition and replicate using a Mini-disk® infiltrometer. There were no differences between the two depths sampled. Similarly, there were no changes in electric conductivity (average 0.1±0.03 dS m-1); pH (8.7±0.2) or calcium carbonate content (43±20 %). Nevertheless, significant differences (p>0.001) were found in soil organic matter. The maximum was found in soils under Quercus (4.7±0.5 %), followed by Stipa (2.2±1.1 %). The soil without vegetation in the areas between olive trees had only 0.7±1.1 % soil organic matter; far from the usual limit advisable for cultivated soils. Soil porosity was also affected in cultivated soils, being 39±5% (total porosity), significantly less than those found under Stipa (46%) and Quercus (51%). Hydraulic conductivity presented a similar pattern to porosity, being higher in soils under Quercus, however further research is needed to clarify this result, as it can also be related to changes detected in soil texture. Sand content, which was different between soil conditions, is highly correlated to hydraulic conductivity. Changes in soil texture can be due to erosive processes that have to be studied to establish the causative relationships between these findings. Acknowledgements: Project CGL 2008-04296. Environmental Impact evaluation through the assessment of soil organic matter resilient forms in soils.

  1. Water status of soil and vegetation in a shortgrass steppe

    Microsoft Academic Search

    O. E. Sala; W. K. Lauenroth; W. J. Parton; M. J. Trlica

    1981-01-01

    In an attempt to describe some major relationships between soil and plant compartments in a shortgrass steppe, the process of water loss from the system and plant water relations throughout a drying cycle were studied. The water supply was manipulated and some soil and plant variables monitored throughout a drying cycle. Leaf conductance and leaf water potential of blue grama

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

    NASA Astrophysics Data System (ADS)

    Biryukov, Mikhail

    2013-04-01

    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.

  3. Impact of vegetation types on soil organic carbon stocks SOC-S in Mediterranean natural areas

    NASA Astrophysics Data System (ADS)

    Parras-Alcántara, Luis; Lozano-García, Beatriz; Cantudo-Pérez, Marta

    2015-04-01

    Soils play a key role in the carbon geochemical cycle because they can either emit large quantities of CO2 or on the contrary they can act as a store for carbon. Agriculture and forestry are the only activities that can achieve this effect through photosynthesis and the carbon incorporation into carbohydrates (Parras-Alcántara et al., 2013). The Mediterranean evergreen oak Woodland (MEOW - dehesa) is a type of pasture with scattered evergreen and deciduous oak stands in which cereals are often grown under the tree cover. It is a system dedicated to the combined production of Iberian swine, sheep, fuel wood, coal and cork as well as to hunting. These semi-natural areas still preserve some of the primitive vegetation of the Mediterranean oak forests. The dehesa is a pasture where the herbaceous layer is comprised of either cultivated cereals such as oat, barley and wheat or native vegetation dominated by annual species, which are used as grazing resources. These Iberian open woodland rangelands (dehesas) have been studied from different points of view: hydrologically, with respect to soil organic matter content, as well as in relation to gully erosion, topographical thresholds, soil erosion and runoff production, soil degradation and management practices…etc, among others. The soil organic carbon stock capacity depends not only on abiotic factors such as the mineralogical composition and the climate, but also on soil use and management (Parras et al., 2014 and 2015). In Spanish soils, climate, use and management strongly affect the carbon variability, mainly in soils in dry Mediterranean climates characterized by low organic carbon content, weak structure and readily degradable soils. Hontoria et al. (2004) emphasized that the climate and soil use are two factors that greatly influence carbon content in the Mediterranean climate. This research sought to analyze the SOC stock (SOCS) variability in MEOW - dehesa with cereals, olive grove and Mediterranean oak forest with different vegetation types (Quercus suber, Quercus ilex, Quercus faginea, Pinus pinaster and Pinus pinea) in The Cardeña-Montoro Natural Park, a nature reserve that consists of a 38,449 ha forested area in southern Spain. Sixty-eight sampling points were selected in the study zone. Each sampling point was analyzed as soil control section with different depth increments (0-25, 25-50, 50-75 and 75-100 cm). The studied soils were classified as Cambisols and the major goal of this research was to study the SOCS variability at regional scale. The total SOCS in The Cardeña-Montoro Natural Park was higher in MEOW with olive grove (111,69 Mg ha-1) and lower in MEOW with Quercus faginea (93,57 Mg ha-1). However, when the top soil (superficial section control) was analyzed, the SOCS was the highest in MEOW with olive grove (70,12 Mg-1) and the lowest in MEOW with Pinus (47,82 Mg ha-1). This research is a preliminary assessment for modeling SOCS at the regional level in Mediterranean natural areas. References Hontoria, C., Rodríguez-Murillo, J., and Saa, A.: Contenido de carbono orgánico en el suelo y factores de control en la España Peninsular, Edafología, 11, 149-155, 2004. Parras-Alcántara, L., Díaz-Jaimes, L., and Lozano-García, B: Organic farming affects C and N in soils under olive groves in Mediterranean areas, Land Degrad. Develop., in press, available online: in Wiley Online Library (wileyonlinelibrary.com), http://dx.doi.org/10.1002/ldr.2231, 2013. Parras-Alcántara, L., Díaz-Jaimes, L., Lozano-García, B., Fernández Rebollo, P., Moreno Elcure, F., Carbonero Muñoz, M.D.: Organic farming has little effect on carbon stock in a Mediterranean dehesa (southern Spain). Catena 113 (2014) 9-17. http://dx.doi.org/10.1016/j.catena.2013.09.002 Parras-Alcántara, L., Díaz-Jaimes, L., and Lozano-García, B.: Management effects on soil organic carbon stock in Mediterranean open rangelands -- treeless grasslands, Land Degrad. Develop., in press, available online: in Wiley Online Library (wileyonlinelibrary.com), http://dx.doi.org/10.1002/ldr.2269, 2015.

  4. Evaluation of Thematic Mapper for detecting soil properties under grassland vegetation

    NASA Technical Reports Server (NTRS)

    Thompson, D. R.; Henderson, K. E.

    1984-01-01

    Analysis of Thematic Mapper data acquired November 15, 1982, over a vegetated site located in the East Texas Timberlands and Claypan area of Texas has indicated that montmorillonitic clay textured soils can be separated from soils with different textures. The difference of TM band 4 (0.76-0.90 micron) and band 7 (2.08-2.35 microns) had an agreement of 55.8 percent with the USDA soil survey for upland clay soils. This compared to 55.9-percent agreement when all six bands (excluding the thermal) were used. The disagreement occurred at the boundary lines as defined by the USDA soil survey and the spectral data. This result is considered to be fairly good, considering the difficulty in placement of soil boundaries by the soil scientist in the field. While the exact influence on the vegetation, and thus the spectral response observed by TM, is not understood at this time, it appears that TM band 7 is responding to the type of mineralogy of the soil and that soil properties important to the plant can be detected using TM.

  5. 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...

  6. One-dimensional snow water and energy balance model for vegetated surfaces

    E-print Network

    Yang, Zong-Liang

    One-dimensional snow water and energy balance model for vegetated surfaces Jiming Jin,2 Xiaogang GCIP Program. Contract grant number: NA46GP0247. #12;K snow thermal conductivity (W mÀ1 KÀ1 ) Ksoil soil thermal conductivity (W mÀ1 KÀ1 ) LAI leaf area index Lli the heat of fusion (J kgÀ1 ) Llv

  7. Long-term investigations on the water budget quantities predicted by the hydro-thermodynamic soil vegetation scheme (HTSVS) – Part I: Description of the model and impact of long-wave radiation, roots, snow, and soil frost

    Microsoft Academic Search

    N. Mölders; U. Haferkorn; J. Döring; G. Kramm

    2003-01-01

    Summary ¶An earlier version of HTSVS was further developed to numerically investigate the long-term evolution of water budget elements (water supply to the atmosphere, ground water recharge, change in storage) in climate studies. In doing so, parameterizations of root effects, infiltration, soil frost, and snow insulation were included into HTSVS to predict these water budget elements for a period of

  8. Infrared temperature measurements over bare soil and vegetation - A HAPEX perspective

    NASA Technical Reports Server (NTRS)

    Carlson, Toby N.; Perry, Eileen M.; Taconet, Odile

    1987-01-01

    Preliminary analyses of aircraft and ground measurements made in France during the HAPEX experiment show that horizontal radiometric surface temperature variations, as viewed by aircraft, can reflect the vertical profile of soil moisture (soil versus root zone) because of horizontal variations in vegetation density. Analyses based on one day's data show that, although horizontal variations in soil moisture were small, the vertical differences between a dry surface and a wet root zone were large. Horizontal temperature differences between bare soil, corn and oats reflect differences in the fractional vegetation cover, as seen by the radiometer. On the other hand, these horizontal variations in radiometric surface temperature seem to reflect real horizontal variations in surface turbulent energy fluxes.

  9. Relationship between soil moisture and vegetation in the Kairouan plain region of Tunisia using low spatial resolution satellite data

    E-print Network

    Boyer, Edmond

    used for vegetation monitoring, crop yield assessment and drought detection [Moulin et al., 1997 with Global Soil Wetness Project, Phase 2 Data, outputs and rainfall events. The soil moisture distribution. The evaluation of vegetation cover and the monitoring of hydric stress are indispensable in these regions

  10. Effect of vegetation on the temporal stability of soil moisture in grass-stabilized semi-arid sand dunes

    NASA Astrophysics Data System (ADS)

    Wang, Tiejun; Wedin, David A.; Franz, Trenton E.; Hiller, Jeremy

    2015-02-01

    Soil moisture is a critical state variable affecting a variety of land surface and subsurface processes. Despite the complex interactions between soil moisture and its controlling factors, the phenomenon of temporal stability of soil moisture (TS SM) has been widely observed under natural conditions. In this study, the control of vegetation on TS SM is investigated by artificially manipulating surface vegetation (e.g., vegetated and de-vegetated plots) in a native grassland-stabilized sand dune area with similar soil texture and topography. Soil moisture data were collected at the depths of 30 cm (within the root zone) and 110 cm (below the root zone) over a period of four years. Using soil moisture data from the de-vegetated plots as a baseline, TS SM within the root zone is shown to be mainly affected by vegetation phenology at the study site. Therefore, the control of vegetation on TS SM varies on both seasonal and annual time scales. The change in the interseasonal patterns of TS SM is tightly related to plant phenology and the control of vegetation on the ranking of mean relative difference (MRD) of soil moisture significantly weakens during non-growing seasons due to diminished root water uptake. It suggests that the timing of sampling schemes (e.g., growing season vs. non-growing season) may alter TS SM patterns. On annual time scales, TS SM is affected by climatic conditions, as the control of vegetation on TS SM becomes stronger under drier conditions. In particular, vegetation tends to create larger contrasts in soil moisture levels between vegetated and de-vegetated plots in drier years. The soil moisture data also provide evidence that vegetation tends to reduce TS SM and increase spatial variability in soil moisture at the study site. The standard deviation of relative difference (SDRD) of soil moisture at the 30 cm depth (within the root zone) is considerably larger in the vegetated plots than those in the de-vegetated plots. As such, the effectiveness of using representative locations for monitoring mean soil moisture conditions in the vegetated plots deteriorates.

  11. The association of selected soil properties with the distribution of native vegetation 

    E-print Network

    Yantis, James H

    1991-01-01

    of NASTER OF SCIENCE August 1991 Najor Subject: Wildlife and Fisheries Sciences THE ASSOCIATION OF SELECTED SOIL PROPERTIES WITH THE DISTRIBUTION OF NATIVE VEGETATION A Thesis by JAMES HUGH YANTIS Approved as to style and content by: Nova J. Shelvy... (Chair of Committee) H E. William E. Grant (Merrber) Michael T Longnecker (Menber) Charles T. Hallmark (Member) id J. Schmidly ( ead of Department) August 1991 111 ABSTRACT The Association of Selected Soil Properties with the Distribution...

  12. Arsenic and heavy metal concentrations in surface soils and vegetables of Feni district in Bangladesh

    Microsoft Academic Search

    R. A. Karim; S. M. Hossain; M. M. H. Miah; K. Nehar; M. S. H. Mubin

    2008-01-01

    An investigation of various heavy metals including the arsenic (As) poisoning in soils and vegetables in five upazillas under\\u000a Feni district of Bangladesh was performed by neutron activation technique using the neutron irradiation facilities of TRIGA\\u000a MARK II research reactor at Bangladesh Atomic Energy Research Establishment (BAERE), Savar, Dhaka. A total of 30 samples (15\\u000a surface soils and 15 foodstuffs)

  13. Rabbit ( Oryctolagus cuniculus L.) impacts on vegetation and soils, and implications for management of wooded rangelands

    Microsoft Academic Search

    David J. Eldridge; Robyn Simpson

    2002-01-01

    Abstract Rabbit warrens,are a distinctive landscape,feature in the semi-arid woodlands,of eastern Australia. Weexamined,the surface morphology,and vegetation composition,of ten rabbit warrens,in central- western NSW in order to assess their roles as a harbor for weedy plants. In general, mounds were characterised by a degraded soil surface dominated by bare soil and coarse gravel, whilst adjacent non-mound,(control) surfaces were,characterised by an extensive

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

    NASA Astrophysics Data System (ADS)

    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

    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.

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

    USGS Publications Warehouse

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

    2013-01-01

    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.

  16. Better use Remotely Sensed Soil Moisture to Initialize Soil Moisture in Global Climate Models

    Microsoft Academic Search

    W. Ni-Meister; J. P. Walker; P. R. Houser

    2001-01-01

    Recent developments in remote sensing technology provide us a great opportunity to improve our understanding of land surface processes by integrating remote sensing data and land surface processes models. Some assimilation methods have been developed to assimilate the remotely sensed data into Soil-Vegetation-Atmosphere Transfer Scheme (SVATS) for better prediction of land surface processes. This study focuses on how to take

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

    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.

  18. Interacting vegetative and thermal contributions to water movement in desert soil

    USGS Publications Warehouse

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

    2011-01-01

    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.

  19. Accumulation and distribution of selenium in some vegetable crops grown in selenate-Se treated clay loam soil

    Microsoft Academic Search

    Karaj S. Dhillon; Surjit K. Dhillon

    2009-01-01

    A greenhouse experiment was conducted to study the accumulation of selenium by some vegetable crops commonly grown in the\\u000a Indian Punjab. Eleven vegetable crops were raised in an alkaline clay loam soil treated with different levels of selenate-Se,\\u000a i.e., 0, 1.25, 2.5 and 5.0 mg·kg?1 soil. Dry matter yield of both edible and inedible portions of different vegetable crops decreased

  20. Vegetation pattern formation due to interactions between water availability and toxicity in plant-soil feedback.

    PubMed

    Marasco, Addolorata; Iuorio, Annalisa; Cartení, Fabrizio; Bonanomi, Giuliano; Tartakovsky, Daniel M; Mazzoleni, Stefano; Giannino, Francesco

    2014-11-01

    Development of a comprehensive theory of the formation of vegetation patterns is still in progress. A prevailing view is to treat water availability as the main causal factor for the emergence of vegetation patterns. While successful in capturing the occurrence of multiple vegetation patterns in arid and semiarid regions, this hypothesis fails to explain the presence of vegetation patterns in humid environments. We explore the rich structure of a toxicity-mediated model of the vegetation pattern formation. This model consists of three PDEs accounting for a dynamic balance between biomass, water, and toxic compounds. Different (ecologically feasible) regions of the model's parameter space give rise to stable spatial vegetation patterns in Turing and non-Turing regimes. Strong negative feedback gives rise to dynamic spatial patterns that continuously move in space while retaining their stable topology. PMID:25338554

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

    NASA Astrophysics Data System (ADS)

    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

    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.

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

    NASA Astrophysics Data System (ADS)

    Schneider, Sébastien; Jacques, Diederik; Mallants, Dirk

    2010-05-01

    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.

  3. Contributions of Understory and/or Overstory Vegetations to Soil Microbial PLFA and Nematode Diversities in Eucalyptus Monocultures

    PubMed Central

    Liu, Zhanfeng; Zhou, Lixia; Fu, Shenglei

    2014-01-01

    Ecological interactions between aboveground and belowground biodiversity have received many attentions in the recent decades. Although soil biodiversity declined with the decrease of plant diversity, many previous studies found plant species identities were more important than plant diversity in controlling soil biodiversity. This study focused on the responses of soil biodiversity to the altering of plant functional groups, namely overstory and understory vegetations, rather than plant diversity gradient. We conducted an experiment by removing overstory and/or understory vegetation to compare their effects on soil microbial phospholipid fatty acid (PLFA) and nematode diversities in eucalyptus monocultures. Our results indicated that both overstory and understory vegetations could affect soil microbial PLFA and nematode diversities, which manifested as the decrease in Shannon–Wiener diversity index (H?) and Pielou evenness index (J) and the increase in Simpson dominance index (?) after vegetation removal. Soil microclimate change explained part of variance of soil biodiversity indices. Both overstory and understory vegetations positively correlated with soil microbial PLFA and nematode diversities. In addition, the alteration of soil biodiversity might be due to a mixing effect of bottom-up control and soil microclimate change after vegetation removal in the studied plantations. Given the studied ecosystem is common in humid subtropical and tropical region of the world, our findings might have great potential to extrapolate to large scales and could be conducive to ecosystem management and service. PMID:24427315

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

    Microsoft Academic Search

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

    1997-01-01

    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

  5. Heavy metal contamination of soil and vegetables in suburban areas of Varanasi, India

    Microsoft Academic Search

    Rajesh Kumar Sharma; Madhoolika Agrawal; Fiona Marshall

    2007-01-01

    Heavy metal contamination of soil resulting from wastewater irrigation is a cause of serious concern due to the potential health impacts of consuming contaminated produce. In this study an assessment is made of the impact of wastewater irrigation on heavy metal contamination of Beta vulgaris (palak); this is a highly nutritious leafy vegetable that is widely cultivated and consumed in

  6. Impact of heavy metal contamination of Bellandur Lake on soil and cultivated vegetation

    Microsoft Academic Search

    H. Lokeshwari; G. T. Chandrappa

    The aim of this study is to assess the extent of heavy metal contamination of vegetation due to irrigation with sewage-fed lake water on agricultural land. Samples of water, soil and crop plants have been analysed for seven heavy metals, viz. Fe, Zn, Cu, Ni, Cr, Pb and Cd using atomic absorption spectrophotometry. The re- sults show the presence of

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

    Microsoft Academic Search

    Brian E. Davies; Helen M. White

    1981-01-01

    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

  8. Soil microbial community structure in relation to vegetation management on former agricultural land

    Microsoft Academic Search

    Katarina Hedlund

    2002-01-01

    Agricultural overproduction has led the European Union to encourage long-term abandonment of agricultural land. To enhance the transition of agricultural land to natural grasslands or forests different management practices in relation to vegetation can be used. The aim of this study was to understand the interactions between plant and associated soil microbial communities during the succession of agricultural land. A

  9. 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...

  10. Distribution of clinically important thermophilic actinomycetes in vegetable substrates and soil in north-western India

    Microsoft Academic Search

    Madhurama Gangwar; Z. U. Khan; H. S. Randhawa; J. Lacey

    1989-01-01

    Medically important thermophilic actinomycetes were isolated from 218 (64%) of 341 samples of vegetable substrates and soil examined from sites in north-western India. Thermoactinomyces vulgaris (T. candidus) was the commonest species, occurring in 56% of samples, followed by Saccharomonospora viridis in 29%, Thermoactinomyces thalpophilus in 27%, Faenia rectivirgula (Micropolyspora faeni) in 21% and Thermoactinomyces sacchari in 14%. T. vulgaris and

  11. Precontact vegetation and soil nutrient status in the shadow of Kohala Volcano, Hawaii

    NASA Astrophysics Data System (ADS)

    Chadwick, Oliver A.; Kelly, Eugene F.; Hotchkiss, Sara C.; Vitousek, Peter M.

    2007-09-01

    Humans colonized Hawaii about 1200 years ago and have progressively modified vegetation, particularly in mesic to dry tropical forests. We use ? 13C to evaluate the contribution of C 3 and C 4 plants to deep soil organic matter to reconstruct pre-human contact vegetation patterns along a wet to dry climate transect on Kohala Mountain, Hawaii Island. Precontact vegetation assemblages fall into three distinct zones: a wet C 3 dominated closed canopy forest where annual rainfall is > 2000 mm, a dry C 4 dominated grassland with annual rainfall < 500 mm, and a broad transition zone between these communities characterized by either C 3 trees with higher water-use efficiency than the rainforest trees or C 3 trees with a small amount of C 4 grasses intermixed. The likelihood of C 4 grass understory decreases with increasing rainfall. We show that the total concentration of rock-derived nutrients in the < 2-mm soil fraction differs in each of these vegetation zones. Nutrient losses are driven by leaching at high rainfall and by plant cycling and wind erosion at low rainfall. By contrast, nutrients are best preserved in surface soils of the intermediate rainfall zone, where rainfall supports abundant plant growth but does not contribute large amounts of water in excess of evapotranspiration. Polynesian farmers exploited these naturally enriched soils as they intensified their upland agricultural systems during the last three centuries before European contact.

  12. DUAL-LOW-FREQUENCY RADAR FOR SOIL MOISTURE UNDER VEGETATION AND AT-DEPTH

    Microsoft Academic Search

    Mahta Moghaddam; Yahya Rahmat-Samii; Ernesto Rodriguez; Delwyn Moller

    To address a key science research topic for the global water and energy cycle, namely measuring soil moisture under substantial vegetation canopies and to useful depths, we have developed a concept for a synthetic aperture radar (SAR) system operating simultaneously at UHF and VHF frequencies. We are currently prototyping key technology items that enable this concept under the NASA Earth

  13. Adsorption and Desorption of Atrazine, Desethylatrazine, Deisopropylatrazine, and Hydroxyatrazine in Vegetated Filter Strip and Cultivated Soil

    Microsoft Academic Search

    Larry Jason Krutz; Scott Allen Senseman; Kevin Joseph McInnes; David Allen Zuberer; Dennis Patrick Tierney

    2003-01-01

    Adsorption and desorption of atrazine and its metabolites in vegetated filter strip soil (VFS) has not been evaluated, yet these data are needed to predict the transport of these compounds through the VFS. Adsorption and desorption parameters for atrazine, desethylatrazine (DEA), deisopropylatrazine (DIA), and hydroxyatrazine (HA) were compared between a cultivated Houston Black clay (CS) and an adjacent 12-year-old VFS

  14. A comparison of soil quality indexing methods for vegetable production systems in Northern California

    Microsoft Academic Search

    S. S. Andrews; D. L. Karlen; J. P. Mitchell

    2002-01-01

    Consultants, farm advisors, resource conservationists, and other land managers may benefit from decision tools that help identify the most sustainable management practices. Indices of soil quality (SQIs) can provide this service. Various methods were tested for choosing a minimum data set (MDS), transforming the indicators, and calculating indices using data from alternative vegetable production systems being evaluated near Davis, California.

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

    E-print Network

    David, Mark B.

    and other heavy equipment are used, but foot traffic can also disturb sites. Past research on human foot, trails, and picnic ar- eas). Human foot traffic has been shown to increase bulk densities on recreationalImpact of Foot Traffic from Military Training on Soil and Vegetation Properties1 CAPTAIN (USAF

  16. Author's personal copy Soil and vegetation as the determinants of lake nitrogen

    E-print Network

    Mazumder, Asit

    Author's personal copy Soil and vegetation as the determinants of lake nitrogen concentrations, rivers and aquifers (Meidinger and Pojar, 1991). High nitrogen concentration can cause lake quality (Vitousek and Howarth, 1991; Carpenter et al., 1998). As nitrogen (N) is a major determinant

  17. 110mAg root and foliar uptake in vegetables and its migration in soil.

    PubMed

    Shang, Z R; Leung, J K C

    2003-01-01

    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

  18. [Soil organic carbon storage changes with land reclamation under vegetation reconstruction on opencast coal mine dump].

    PubMed

    Li, Jun-Chao; Dang, Ting-Hui; Guo, Sheng-Li; Xue, Jiang; Tang, Jun

    2014-10-01

    Vegetation reconstruction was an effective solution to reclaim the opencast coal mine dump which was formed in the process of mining. To understand the impact of the vegetation reconstruction patterns' on the mine soil organic carbon (SOC) storage was essential for selecting the methods of vegetation restoration and also important for accurately estimating the potential of the soil carbon sequestration. The study area was on the Heidaigou opencast coal mine, which was 15 years reclaimed coal mine dump in Zhungeer, Inner Mongolia autonomous region, we selected 5 vegetation reconstruction patterns (natural recovery land, grassland, bush land, mixed woodland of arbor and bush, arbor land), and 16 vegetation types, 408 soil samples (0-100 m), to study the effect of the vegetation reconstruction patterns on the SOC storage. The results were showed as follows: (1) on the reclaimed coal mine dump, the vegetation reconstruction patterns significantly affected the SOC content and its distribution in the soil profile (P < 0.05). The surface 0-10 cm SOC content was grassland > shrub land > arbor forest > mixed forest of arbor and shrub > natural recovery land, in which the grassland, shrub land and arbor forest were about 2.2, 1.3, and 1.3 times of natural recovery land (2.14 g · kg(-1)) respectively. The total nitrogen (TN) showed the similar trends. (2) Among the vegetation types, Medicago sativa had the highest surface SOC content (5.71 g · kg(-1)) and TN content (0.49 g · kg(-1)), that were 171.3% and 166.7% higher than the natural recovery land, and two times of Hippophae rhamnoides, Amorpha fruticosa + Pinus tabulaeformis and Robinia pseudoacacia. (3) The effect of vegetation types on SOC mainly concentrated in the 0-20 cm depth, and the effect on TN accounted for 40 cm. (4) For the SOC storage, the order was original landform area > reclaimed dump > new dump and grassland > woodland (including arbor and shrub land). After 15 years revegetation, the soil carbon storage of the grassland, shrub land and arbor land were increased by 15.47 t · hm(-2), 6.93 t · hm(-2) and 6.95 t · hm(-2) respectively in the 100 cm depth, which were equivalent to 2/3, 1/2 and 1/2 of the original landform levels. The results showed a great ability of carbon sequestration. PMID:25693392

  19. Heterogeneity and scaling in soil-vegetation atmosphere systems: implications for pattern analysis (Invited)

    NASA Astrophysics Data System (ADS)

    Pachepsky, Y. A.

    2009-12-01

    Advances in sensor physics and technology create opportunities for explicit consideration of patterns in soil-vegetation-atmosphere systems (SVAS). The purpose of this talk is to provoke discussion on the current status of pattern analysis and interpretation in SVAS. The explicit consideration of patterns requires observations and analysis at scales that are both coarser and finer than the scale of interest. Within-scale scaling relationships are often observed in SVAS components. However, direct scaling relationships have not been discovered between scales, possibly because the different scales provide different types of information about the SVAS, use different variables to characterize SVAS, and exhibit different variability of the system. To transcend the scales, models are needed that explicitly treat the fine-scale heterogeneity and rare occurrences that control processes at the coarser scale. As patterns are generated from simulations and or/or observations, methods are needed for pattern characterization and comparison. One promising direction here is the symbolic representation of patterns which leads to the exploitation of methods developed in the bioinformatics community. Examples drawn from soil hydrology and micrometeorology will be used in illustrations to make the argument that observation and analysis of patterns is the important part of understanding and quantifying relationships between structure, functioning and self-organization in SVAS and their components.

  20. Evaluation of NLDAS-2 Multi-Model Simulated Soil Moisture Using the Observations from North American Soil Moisture Dataset (NASMD)

    NASA Astrophysics Data System (ADS)

    Xia, Y.; Ek, M. B.; Wu, Y.; Ford, T.; Quiring, S. M.

    2014-12-01

    The North American Land Data Assimilation System phase 2 (NLDAS-2, http://www.emc.ncep.noaa.gov/mmb/nldas/) has generated 35-years (1979-2013) of hydrometeorological products from four state-of-the-art land surface models (Noah, Mosaic, SAC, VIC). These products include energy fluxes, water fluxes, and state variables. Soil moisture is one of the most important state variables in NLDAS-2 as it plays a key role in land-atmosphere interaction, regional climate and ecological model simulation, water resource management, and other study areas. The soil moisture data from these models have been used for US operational drought monitoring activities, water resources management and planning, initialization of regional weather and climate models, and other meteorological and hydrological research purposes. However, these data have not yet been comprehensively evaluated due to the lack of extensive soil moisture observations. In this study, observations from over 1200 sites in the North America compiled from 27 observational networks in the North American Soil Moisture Database (NASMD, http://soilmoisture.tamu.edu/) were used to evaluate the model-simulated daily soil moisture for different vegetation cover varying from grassland to forest, and different soil texture varying from sand to clay. Seven states in the United States from NASMD were selected based on known measurement error estimates for the evaluation. Statistical metrics, such as anomaly correlation, root-mean-square errors (RMSE), and bias are computed to assess NLDAS-2 soil moisture products. Three sensitivity tests were performed using the Noah model to examine the effect of soil texture and vegetation type mismatch on NLDAS-2 soil moisture simulation. In the first test, site observed soil texture was used. In the second test, site observed vegetation type/land cover was used. In the third test, both site observed soil texture and vegetation type were used. The results from three sensitivity tests will be compared with NLDAS-2 Noah and observed soil moisture. This presentation reports major results from this evaluation.

  1. Interacting vegetative and thermal contributions to water movement in desert soil

    USGS Publications Warehouse

    Garcia, C.A.; Andraski, B.J.; Stonestrom, D.A.; Cooper, C.A.; Šim?nek, J.; Wheatcraft, S.W.

    2011-01-01

    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.

  2. Trampling resistance of tropical rainforest soils and vegetation in the wet tropics of north east Australia.

    PubMed

    Talbot, L M; Turton, S M; Graham, A W

    2003-09-01

    Controlled trampling was conducted to investigate the trampling resistance of contrasting high fertility basaltic and low fertility rhyolitic soils and their associated highland tropical rainforest vegetation in north east Australia's Wet Tropics. Although this approach has been taken in numerous studies of trampling in a variety of ecosystem types (temperate and subtropical forest, alpine shrubland, coral reef and seagrass beds), the experimental method does not appear to have been previously applied in a tropical rainforest context. Ground vegetation cover and soil penetration resistance demonstrated variable responses to trampling. Trampling, most noticeably after 200 and 500 passes reduced organic litter cover. Bulk density increased with trampling intensity, particularly on basalt soils as rhyolite soils appeared somewhat resistant to the impacts of trampling. The permeability of the basalt and rhyolite soils decreased markedly with increased trampling intensity, even after only 75 passes. These findings suggest physical and hydrological changes may occur rapidly in tropical rainforest soils following low levels of trampling, particularly on basalt soils. PMID:12927152

  3. Thresholds in vegetation responses to drought: Implications for rainfall-runoff modeling

    NASA Astrophysics Data System (ADS)

    Tague, C.; Dugger, A. L.

    2011-12-01

    While threshold behavior is often associated with soil and subsurface runoff generation, dynamic vegetation responses to water stress may be an important contributor to threshold type behavior in rainfall runoff models. Vegetation water loss varies with vegetation type and biomass and transpiration dynamics in many settings are regulated by stomatal function. In water limited environments the timing and frequency of stomatal closure varies from year to year as a function of water stress. Stomatal closure and associated fine time scale (hourly to weekly) plant transpiration may appear as threshold (on/off) behavior. Total seasonal to annual plant water use, however, typically show a continuous relationship with atmospheric conditions and soil moisture. Thus while short-time scale behavior may demonstrate non-linear, threshold type behavior, continuous relationships at slightly longer time scales can be used to capture the role of vegetation mediated water loss and its associated impact on storage and runoff. Many rainfall runoff models rely on these types of relationships. However these relationships may change if water stress influences vegetation structure as it does in drought conditions. Forest dieback under drought is a dramatic example of a threshold event, and one that is expected to occur with increasing frequency under a warmer climate. Less dramatic but still important are changes in leaf and root biomass in response to drought. We demonstrate these effects using a coupled ecosystem carbon cycling and hydrology model and show that by accounting for drought driven changes in vegetation dynamics we improve our ability to capture inter-annual variation in streamflow for a semi-arid watershed in New Mexico. We also use the model to predict spatial patterns of more catastrophic vegetation dieback with moisture stress and show that we can accurately capture the spatial pattern of ponderosa pine dieback during a early 2000s drought in New Mexico. We use these simulations to derive characteristics of threshold water stress conditions where vegetation structural responses become significant for runoff predictions.

  4. 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...

  5. Soil-vegetation feedbacks in dynamic landscapes: Implications for restoration

    Technology Transfer Automated Retrieval System (TEKTRAN)

    State changes from perennial grasslands to shrub-dominated systems characterize much of the arid regions of the world, including the American Southwest. Where this conversion is associated with a change in soil surface texture, near-surface water availability can be increased or reduced with importa...

  6. Soil changes after four years of organic vegetable production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In 2002, scientists at the Lane Agricultural Center in southeastern Oklahoma began a study to explore the potential for organic agricultural production. Land was certified as organic according to the guidelines of the National Organic Program. At the beginning of the study, soil samples were taken...

  7. Effect of vegetation rehabilitation on soil carbon and its fractions in mu us desert, northwest china.

    PubMed

    Liu, Jia-Bin; Zhang, Yu-Qing; Wu, Bin; Qin, Shu-Gao; Jia, Xin; Fa, Ke-Yu; Feng, Wei; Lai, Zong-Rui

    2015-01-01

    Although vegetation rehabilitation on semi-arid and arid regions may enhance soil carbon sequestration, its effects on soil carbon fractions remain uncertain. We carried out a study after planting Artemisia ordosica (AO, 17 years), Astragalus mongolicum (AM, 5 years), and Salix psammophila (SP, 16 years) on shifting sand land (SL) in the Mu Us Desert, northwest China. We measured total soil carbon (TSC) and its components, soil inorganic carbon (SIC) and soil organic carbon (SOC), as well as the light and heavy fractions within soil organic carbon (LF-SOC and HF-SOC), under the SL and shrublands at depths of 100 cm. TSC stock under SL was 27.6 Mg ha(-1), and vegetation rehabilitation remarkably elevated it by 40.6 Mgha(-1), 4.5 Mgha(-1), and 14.1 Mgha(-1) under AO, AM and SP land, respectively. Among the newly formed TSC under the three shrublands, SIC, LF-SOC and HF-SOC accounted for 75.0%, 10.7% and 13.1% for AO, respectively; they made up 37.0%, 50.7% and 10.6% for AM, respectively; they occupied 68.6%, 18.8% and 10.0% for SP, respectively. The accumulation rates of TSC within 0-100 cm reached 238.6 g m(-2)y(-1), 89.9 g m(-2)y(-1) and 87.9 g m(-2)y(-1) under AO, AM and SP land, respectively. The present study proved that the accumulation of SIC considerably contributed to soil carbon sequestration, and vegetation rehabilitation on shifting sand land has a great potential for soil carbon sequestration. PMID:25747239

  8. Phthalic Acid Esters in Soils from Vegetable Greenhouses in Shandong Peninsula, East China

    PubMed Central

    Chai, Chao; Cheng, Hongzhen; Ge, Wei; Ma, Dong; Shi, Yanxi

    2014-01-01

    Soils at depths of 0 cm to 10 cm, 10 cm to 20 cm, and 20 cm to 40 cm from 37 vegetable greenhouses in Shandong Peninsula, East China, were collected, and 16 phthalic acid esters (PAEs) were detected using gas chromatography-mass spectrometry (GC-MS). All 16 PAEs could be detected in soils from vegetable greenhouses. The total of 16 PAEs (?16PAEs) ranged from 1.939 mg/kg to 35.442 mg/kg, with an average of 6.748 mg/kg. Among four areas, including Qingdao, Weihai, Weifang, and Yantai, the average and maximum concentrations of ?16PAEs in soils at depths of 0 cm to 10 cm appeared in Weifang, which has a long history of vegetable production and is famous for extensive greenhouse cultivation. Despite the different concentrations of ?16PAEs, the PAE compositions were comparable. Among the 16 PAEs, di(2-ethylhexyl) phthalate (DEHP), di-n-octyl phthalate (DnOP), di-n-butyl phthalate (DnBP), and diisobutyl phthalate (DiBP) were the most abundant. Compared with the results on agricultural soils in China, soils that are being used or were used for vegetable greenhouses had higher PAE concentrations. Among PAEs, dimethyl phthalate (DMP), diethyl phthalate (DEP) and DnBP exceeded soil allowable concentrations (in US) in more than 90% of the samples, and DnOP in more than 20%. Shandong Peninsula has the highest PAE contents, which suggests that this area is severely contaminated by PAEs. PMID:24747982

  9. Evaluation of the soil biological activity in a remediation soil assay using organic amendments and vegetal cover.

    PubMed

    Sastre-Conde, Isabel; Cabezas, José Gerardo; Guerrero, Ana; Vicente, María Angeles; Lobo, María Del Carmen

    2007-05-25

    The recovery of a degraded soil was assayed in greenhouse conditions by applying organic amendments and revegetation with grasses. Two types of organic residues were used: sewage sludge composted with pruning waste (CPW), at 8.5 and 85 Mg ha(-1) and sewage sludge treated by thermal drying (TD), at 22 and 46 Mg ha(-1). The vegetal cover was established by sowing different herbaceous species commonly used in the revegetation of degraded alkaline soils (100 and 200 Kg of seeds ha(-1)). The chemical soil parameters and enzymatic activities (alkaline phosphatase, urease, and beta-glucosidase) and the vegetal biomass were evaluated. The type of amendment and the doses applied had different effects on the soil characteristics. However sowing dose did not have a significant effect on the parameters analysed. Organic matter was the only soil parameter affected by the interaction between the sowing rate and the amendment dose. The phosphatase and glucosidase activities showed significant correlation with the percentage of N in the leaves and stems, furthermore the phosphate activity was significantly related to the dry weight of leaves and stems. PMID:17306865

  10. Structure and condition of soil-vegetation cover in the Klyazma river basin applying remote sensing data

    NASA Astrophysics Data System (ADS)

    Mishchenko, Natalia; Trifonova, Tatiana; Repkin, Roman

    2015-04-01

    Constant observation of vegetation and soil cover is one of the key issues of river basins ecologic monitoring. It is necessary to consider that observation objects have been continuously changing and these changes are comprehensive and depend on temporal and dimensional parameters. Remote sensing data, embracing vast areas and reflecting various interrelations, allow excluding accidental and short-term changes though concentrating on the transformation of the observed river basin ecosystem environmental condition. The research objective is to assess spatial-temporal peculiarities of soil-vegetation structure formation in the Klyazma basin as a whole and minor river basins within the area. Research objects are located in the centre of European Russia. Data used in our research include both statistic and published data, characterizing soil-vegetation cover of the area, space images Landsat. Research methods: Remote data analysis for assessing land utilization structure and soil-vegetation condition according to NDVI. Laying soil-geobotanic landscape profiles river valleys slopes. Phytomass reserve, phytoproductivity, soil fertility characteristics assessment. NDVI computation for each image pixel helped to map general condition of the Klyazma vegetation cover and to determine geographic ranges without vegetation or with depressed vegetation. For instance high vegetation index geographic range has been defined which corresponded to Vladimir Opolye characterized with the most fertile grey forest soil in the region. Comparative assessment of soil vegetation cover of minor river basins within the Klyazma basin, judging by the terrestrial data, revealed its better condition in the Koloksha basin which is also located in the area of grey forest soil. Besides here the maximum value of vegetation index for all phytocenosis was detected. In the research the most dynamically changing parts of the Klyazma basin have been determined according to NDVI dynamics analysis. Analyzing the reasons for such changes of NDVI the most significant ecologic processes in the region connected to the changes of vegetation cover condition have been revealed. Fields overgrowing and agricultural crops replacement are the most important of them. Soil-geobotanic profiles, laid in minor river basin of the Sudogda, allowed to reveal various vegetation association and to describe the confined soil profile. It is shown that well drained landscape forms correspond to arboreal vegetation type, more humidified elements of the landscape are occupied with gramineous meadow vegetation. There is sand and clay sand under mixed forest humus horizon. In pinewood forests light loam prevails in surface horizons. The results can be used for environmental monitoring of the river basins and for rational agricultural structuring.

  11. Chemical-Specific Representation of Air-Soil Exchange and Soil Penetration in Regional Multimedia Models

    SciTech Connect

    McKone, T.E.; Bennett, D.H.

    2002-08-01

    In multimedia mass-balance models, the soil compartment is an important sink as well as a conduit for transfers to vegetation and shallow groundwater. Here a novel approach for constructing soil transport algorithms for multimedia fate models is developed and evaluated. The resulting algorithms account for diffusion in gas and liquid components; advection in gas, liquid, or solid phases; and multiple transformation processes. They also provide an explicit quantification of the characteristic soil penetration depth. We construct a compartment model using three and four soil layers to replicate with high reliability the flux and mass distribution obtained from the exact analytical solution describing the transient dispersion, advection, and transformation of chemicals in soil with fixed properties and boundary conditions. Unlike the analytical solution, which requires fixed boundary conditions, the soil compartment algorithms can be dynamically linked to other compartments (air, vegetation, ground water, surface water) in multimedia fate models. We demonstrate and evaluate the performance of the algorithms in a model with applications to benzene, benzo(a)pyrene, MTBE, TCDD, and tritium.

  12. The Impact of Soil Reflectance on the Quantification of the Green Vegetation Fraction from NDVI

    NASA Technical Reports Server (NTRS)

    Montandon, L. M.; Small, E. E.

    2008-01-01

    The green vegetation fraction (Fg) is an important climate and hydrologic model parameter. A common method to calculate Fg is to create a simple linear mixing rnodeP between two NDVI endmembers: bare soil NDVI (NDVI(sub o)) and full vegetation NDVI (NDVI(sub infinity)). Usually it is assumed that NDVI(sub o), is close to zero (NDVI(sub o) approx.-0.05) and is generally chosen from the lowest observed NDVI values. However, the mean soil NDVI computed from 2906 samples is much larger (NDVI=0.2) and is highly variable (standard deviation=O. 1). We show that the underestimation of NDVI(sub o) yields overestimations of Fg. The largest errors occur in grassland and shrubland areas. Using parameters for NDVI(sub o) and NDVI(sub infinity) derived from global scenes yields overestimations of Fg ((Delta) Fg*) that are larger than 0.2 for the majority of U.S. land cover types when pixel NDVI values are 0.2soil reflectance.

  13. Oscillations in a simple climate-vegetation model

    NASA Astrophysics Data System (ADS)

    Rombouts, J.; Ghil, M.

    2015-02-01

    We formulate and analyze a simple dynamical systems model for climate-vegetation interaction. The planet we consider consists of a large ocean and a land surface on which vegetation can grow. The temperature affects vegetation growth on land and the amount of sea ice on the ocean. Conversely, vegetation and sea ice change the albedo of the planet, which in turn changes its energy balance and hence the temperature evolution. Our highly idealized, conceptual model is governed by two nonlinear, coupled ordinary differential equations, one for global temperature, the other for vegetation cover. The model exhibits either bistability between a vegetated and a desert state or oscillatory behavior. The oscillations arise through a Hopf bifurcation off the vegetated state, when the death rate of vegetation is low enough. These oscillations are anharmonic and exhibit a sawtooth shape that is characteristic of relaxation oscillations, as well as suggestive of the sharp deglaciations of the Quaternary. Our model's behavior can be compared, on the one hand, with the bistability of even simpler, Daisyworld-style climate-vegetation models. On the other hand, it can be integrated into the hierarchy of models trying to simulate and explain oscillatory behavior in the climate system. Rigorous mathematical results are obtained that link the nature of the feedbacks with the nature and the stability of the solutions. The relevance of model results to climate variability on various time scales is discussed.

  14. Oscillations in a simple climate-vegetation model

    NASA Astrophysics Data System (ADS)

    Rombouts, J.; Ghil, M.

    2015-05-01

    We formulate and analyze a simple dynamical systems model for climate-vegetation interaction. The planet we consider consists of a large ocean and a land surface on which vegetation can grow. The temperature affects vegetation growth on land and the amount of sea ice on the ocean. Conversely, vegetation and sea ice change the albedo of the planet, which in turn changes its energy balance and hence the temperature evolution. Our highly idealized, conceptual model is governed by two nonlinear, coupled ordinary differential equations, one for global temperature, the other for vegetation cover. The model exhibits either bistability between a vegetated and a desert state or oscillatory behavior. The oscillations arise through a Hopf bifurcation off the vegetated state, when the death rate of vegetation is low enough. These oscillations are anharmonic and exhibit a sawtooth shape that is characteristic of relaxation oscillations, as well as suggestive of the sharp deglaciations of the Quaternary. Our model's behavior can be compared, on the one hand, with the bistability of even simpler, Daisyworld-style climate-vegetation models. On the other hand, it can be integrated into the hierarchy of models trying to simulate and explain oscillatory behavior in the climate system. Rigorous mathematical results are obtained that link the nature of the feedbacks with the nature and the stability of the solutions. The relevance of model results to climate variability on various timescales is discussed.

  15. Assessment of heavy metal pollution in vegetables and relationships with soil heavy metal distribution in Zhejiang province, China.

    PubMed

    Ye, Xuezhu; Xiao, Wendan; Zhang, Yongzhi; Zhao, Shouping; Wang, Gangjun; Zhang, Qi; Wang, Qiang

    2015-06-01

    There are increasing concerns on heavy metal contaminant in soils and vegetables. In this study, we investigated heavy metal pollution in vegetables and the corresponding soils in the main vegetable production regions of Zhejiang province, China. A total of 97 vegetable samples and 202 agricultural soil samples were analyzed for the concentrations of Cd, Pb, As, Hg, and Cr. The average levels of Cd, Pb, and Cr in vegetable samples [Chinese cabbage (Brassica campestris spp. Pekinensis), pakchoi (Brassica chinensis L.), celery (Apium graveolens), tomato (Lycopersicon esculentum), cucumber (Colletotrichum lagenarium), cowpea (Vigna unguiculata), pumpkin (Cucurbita pepo L.), and eggplant (Solanum melongena)] were 0.020, 0.048, and 0.043 mg kg(-1), respectively. The Pb and Cr concentrations in all vegetable samples were below the threshold levels of the Food Quality Standard (0.3 and 0.5 mg kg(-1), respectively), except that two eggplant samples exceeded the threshold levels for Cd concentrations (0.05 mg kg(-1)). As and Hg contents in vegetables were below the detection level (0.005 and 0.002 mg kg(-1), respectively). Soil pollution conditions were assessed in accordance with the Chinese Soil Quality Criterion (GB15618-1995, Grade II); 50 and 68 soil samples from the investigated area exceeded the maximum allowable contents for Cd and Hg, respectively. Simple correlation analysis revealed that there were significantly positive correlations between the metal concentrations in vegetables and the corresponding soils, especially for the leafy and stem vegetables such as pakchoi, cabbage, and celery. Bio-concentration factor values for Cd are higher than those for Pb and Cr, which indicates that Cd is more readily absorbed by vegetables than Pb and Cr. Therefore, more attention should be paid to the possible pollution of heavy metals in vegetables, especially Cd. PMID:26013654

  16. A simulation model of vegetation temperature based on physiological characteristics

    NASA Astrophysics Data System (ADS)

    Lin, Wei; Wang, Ji-yuan; Chen, Yu-hua; Wang, Ji-jun; Su, Rong-hua

    2014-11-01

    To simulate vegetation temperature is an important part in the thermal infrared simulation. In previous physical models, the physiological characteristics of vegetation has only considered the influence of transpiration to temperature, but without respiration, and the aerodynamics model which has been used before needs more model parameters and they are difficult to obtain. In the present paper, a transpiration rate model has been used, in which the latent heat component of the vegetation has been optimized and the respiration component has been joined. Then the physiological model of vegetation temperature simulation has been established which improves the original vegetation energy budget theory. Experimental verification and comparison shows that the maximum simulation error of physiological model is within 2°, the average error is within 1°. It seems that the simulation accuracy is significantly better than the previous physical model that will improve the overall thermal infrared simulation accuracy.

  17. Investigation of North American vegetation variability under recent climate - A study using the SSiB4/TRIFFID biophysical/dynamic vegetation model

    NASA Astrophysics Data System (ADS)

    Zhang, Z.; Xue, Y.; MacDonald, G. M.; Cox, P. M.; Collatz, G. J.

    2014-12-01

    This study applies a 2-D biophysical model/dynamic vegetation model (SSiB4/TRIFFID) to investigate the dominant factors affecting vegetation equilibrium conditions, to assess the model's ability to simulate seasonal to decadal variability for the past 60 years (from 1948 through 2008), to analyze vegetation spatiotemporal characteristics over North America (NA), and to identify the relationships between vegetation and climate. Satellite data are employed as constraints for this study. The optimum temperature for photosynthesis, leaf drop threshold temperatures, and competition coefficients in the Lotka-Volterra equation have major impact on the vegetation spatial distribution and reach to equilibrium status in SSiB4/TRIFFID. The phenomenon that vegetation competition coefficients affect equilibrium suggests the importance of including biotic effects in dynamical vegetation modeling. SSiB4/TRIFFID can reproduce the features of NA distributions of dominant vegetation types, the vegetation fraction, and LAI, including its seasonal, interannual, and decadal variability, well compared with satellite-derived products. The NA LAI shows an increasing trend after the 1970s in responding to warming. Meanwhile, both simulation and satellite observations reveal LAI increased in the southeastern U.S. starting from the 1980s. The effects of the severe drought during 1987-1992 and the last decade in the southwestern U.S.on vegetation are also evident from the simulated and satellite-derived LAIs.Both simulated and satellite-derived LAIs have the strongest correlations with air temperature at northern middle to high latitudes in spring through their effect on photosynthesis and phenological processes. During the summer, the areas with positive correlations retreat northward. Meanwhile, in southwestern dry lands, the negative correlations appear due to the heat stress there during the summer. Furthermore, there are also positive correlations between soil wetness and LAI, which increases from spring to summer.

  18. Modelling Vegetation Cover Dynamics of the Niger Floodplain in Mali, Westafrica, Using Multitemporal MERIS Full Resolution and TERRA -ASTER Data

    NASA Astrophysics Data System (ADS)

    Seiler, Ralf

    This presentation aims at showing the potential of a combined use of multi-temporal data from two different sensors (MERIS and TERRA ASTER) for an analysis of vegetation cover changes in semi-arid environments. While MERIS data mainly provide information about the vegetation cover density, ASTER data were used to analyse soil properties -especially soil brightness and soil wetness. An algorithm is proposed that uses atmospherically corrected surface reflectance values from MERIS and ASTER measurements. These values are subsequently splitted into a signal component that is caused by the vegetation cover and the background component (triggered by soil properties) using a linear spectral unmixing approach. Vegetation cover then is described by Vegetation Indices (MGVI, NDVI / SAVI) that were calculated from the vegetation signal component. Finally, these vegetation parameter were classified for all multi-temporal MERIS data using the EM algorithm to derive the temporal behaviour of vegetation pattern at the Inland Delta. The algorithm provides, as results, a fractional vegetation cover, a vegetation density value and information on the soil type. A detailed mapping of the spatio-temporal vegetation cover patterns for the Niger Inland Delta during the period of 2002 -2005 is another outcome of this study in addition to an in-depth evaluation of the applicability of the used VIs for environments with sparse vegetation covers. Located in the western Sahel of Africa, (1330' N -17 N and 230' W -530' W), the Niger Inland Delta is one of the largest floodplains in the world. The geographic term "Niger Inland Delta" represents a vast, extremely flat area of around 40.000 km extend, which is annually inundated by water of the Niger -Bani riversystem. In contrast to its semi -arid surrounding, the delta's ecology can be described as a mosaic of permanent, periodical and episodically flooded areas. Their extend varies both in scale and time due to irregularities of amount as well as seasonal distribution of the annual rainfall in the catchment areas and the resulting water supply contributed by the river system. Due to the relatively good availability of (surface) water, the Niger Inland Ecosystem serves as stop-over for many migrating birds and other wildlife species as well as an eonomic base for farmers and pastoral people. As a consequence, the entire Niger Inland Delta has been declared as protected RAMSAR site in 2004. Interaction among pre-flood, flood and post-flood conditions strongly affect the patterns of landcover in and around the delta as vegetation cover is strongly correlated with the availability of surface water. The Inland Delta is dominantly covered by (irrigated) fields or grasslands during flood and post-flood periods (October to January), while most of the photosynthetically active vegetation withers during the rest of the year. This yields in highly vibrant vegetation cover, although the vegetation cover density remains low even during flood period for most of the Inland Delta. This study analyses the intra-annual dynamics as well as changes in vegetation cover between individual years by interpreting 17 MERIS full resolution data over the period from Aug. 2002 to June 2005. MERIS sensor provides measurements from 15 spectral bands within the VIS and NIR part of the EMS with 300 m spatial resolution. Thus allowing for analyses at a regional scale level with high sensitivity for the amount of green vegetation. Short time dynamics of vegetation are related to changes in vegetation cover density. These changes were modelled with Vegetation Indices (VI) as parameter. To overcome well known problems related with NDVIs dependence of illumination and viewing angle, background signal (soil brightness) and changes in humidity, the MGVI was used as indix to derive more sophisticated biophysical information in addition to the classical NDVI. Soil types influence the remotely sensed signal significantly due to the overall sparse vegetation cover. Information about soil brightness and wetness were derived from dat

  19. Comparison of Soil Hydraulic Parameterizations for Mesoscale Meteorological Models.

    NASA Astrophysics Data System (ADS)

    Braun, Frank J.; Schädler, Gerd

    2005-07-01

    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.

  20. Vegetated Roof Water-Balance Model: Experimental and Model Results

    E-print Network

    . Author keywords: Vegetated roof; Water balance model; Evapotranspiration; Experiment. Introduction A dominant factor that alters natural hydrologic systems is urbani- zation (Claessens et al. 2006). A primary loads within highly urbanized areas with unutilized rooftop space. In some highly urbanized areas

  1. Stochastic Modeling of Soil Salinity

    E-print Network

    Suweis, S; Van der Zee, S E A T M; Daly, E; Maritan, A; Porporato, A; 10.1029/2010GL042495

    2012-01-01

    A minimalist stochastic model of primary soil salinity is proposed, in which the rate of soil salinization is determined by the balance between dry and wet salt deposition and the intermittent leaching events caused by rainfall events. The long term probability density functions of salt mass and concentration are found by reducing the coupled soil moisture and salt mass balance equation to a single stochastic differential equation driven by multiplicative Poisson noise. The novel analytical solutions provide insight on the interplay of the main soil, plant and climate parameters responsible for long-term soil salinization. In particular, they show the existence of two distinct regimes, one where the mean salt mass remains nearly constant (or decreases) with increasing rainfall frequency, and another where mean salt content increases markedly with increasing rainfall frequency. As a result, relatively small reductions of rainfall in drier climates may entail dramatic shifts in long-term soil salinization trend...

  2. Model for the genesis of coastal dune fields with vegetation

    Microsoft Academic Search

    Eric J. R. Parteli; Orencio Durán; Hans J. Herrmann

    2011-01-01

    Vegetation greatly affects the formation and dynamics of dune fields in coastal areas. In the present work, we use dune modeling in order to investigate the genesis and early development stages of coastal dune fields in the presence of vegetation. The model, which consists of a set of coupled equations for the turbulent wind field over the landscape, the saltation

  3. Dynamic floodplain vegetation model development for the Kootenai River, USA.

    PubMed

    Benjankar, Rohan; Egger, Gregory; Jorde, Klaus; Goodwin, Peter; Glenn, Nancy F

    2011-12-01

    The Kootenai River floodplain in Idaho, USA, is nearly disconnected from its main channel due to levee construction and the operation of Libby Dam since 1972. The decreases in flood frequency and magnitude combined with the river modification have changed the physical processes and the dynamics of floodplain vegetation. This research describes the concept, methodologies and simulated results of the rule-based dynamic floodplain vegetation model "CASiMiR-vegetation" that is used to simulate the effect of hydrological alteration on vegetation dynamics. The vegetation dynamics are simulated based on existing theory but adapted to observed field data on the Kootenai River. The model simulates the changing vegetation patterns on an annual basis from an initial condition based on spatially distributed physical parameters such as shear stress, flood duration and height-over-base flow level. The model was calibrated and the robustness of the model was analyzed. The hydrodynamic (HD) models were used to simulate relevant physical processes representing historic, pre-dam, and post-dam conditions from different representative hydrographs. The general concept of the vegetation model is that a vegetation community will be recycled if the magnitude of a relevant physical parameter is greater than the threshold value for specific vegetation; otherwise, succession will take place toward maturation stage. The overall accuracy and agreement Kappa between simulated and field observed maps were low considering individual vegetation types in both calibration and validation areas. Overall accuracy (42% and 58%) and agreement between maps (0.18 and 0.27) increased notably when individual vegetation types were merged into vegetation phases in both calibration and validation areas, respectively. The area balance approach was used to analyze the proportion of area occupied by different vegetation phases in the simulated and observed map. The result showed the impact of the river modification and hydrological alteration on the floodplain vegetation. The spatially distributed vegetation model developed in this study is a step forward in modeling riparian vegetation succession and can be used for operational loss assessment, and river and floodplain restoration projects. PMID:21852032

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

    PubMed Central

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

    2002-01-01

    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. PMID:12039728

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

    PubMed

    Vargas, Rodrigo; Allen, Michael F

    2008-07-01

    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

  6. The effects of vegetation and soil hydraulic properties on passive microwave sensing of soil moisture: Data report for the 1982 fiels experiments

    NASA Technical Reports Server (NTRS)

    Oneill, P.; Jackson, T.; Blanchard, B. J.; Vandenhoek, R.; Gould, W.; Wang, J.; Glazar, W.; Mcmurtrey, J., III

    1983-01-01

    Field experiments to (1) study the biomass and geometrical structure properties of vegetation canopies to determine their impact on microwave emission data, and (2) to verify whether time series microwave data can be related to soil hydrologic properties for use in soil type classification. Truck mounted radiometers at 1.4 GHz and 5 GHz were used to obtain microwave brightness temperatures of bare vegetated test plots under different conditions of soil wetness, plant water content and canopy structure. Observations of soil moisture, soil temperature, vegetation biomass and other soil and canopy parameters were made concurrently with the microwave measurements. The experimental design and data collection procedures for both experiments are documented and the reduced data are presented in tabular form.

  7. [Soil respiration dynamics and its controlling factors of typical vegetation communities on meadow steppes in the western Songnen Plain].

    PubMed

    Wang, Ming; Liu, Xing-Tu; Li, Xiu-Jun; Zhang, Ji-Tao; Wang, Guo-Dong; Lu, Xin-Rui; Li, Xiao-Yu

    2014-01-01

    In order to accurately explore the soil respiration dynamics and its controlling factors of typical vegetation types in the western Songnen Plain, soil respiration rates of Chloris virgata, Puccinellia distans, Phragmites australis and Leymus chinensis communities were measured. The results showed that the diurnal curves of soil respiration rates of the four vegetation communities had simple peak values, which appeared at 11:00-15:00, and the valley values occurred at 21:00-1:00 or 3:00-5:00. The seasonal dynamic patterns of their soil respiration rates were similar, with the maximum (3.21-4.84 micromol CO2 x m(-2) x s(-1)) occurring in July and August and the minimum (0.46-1.51 micromol CO2 x m(-2) x s(-1)) in October. The soil respiration rates of the four vegetation communities had significant exponential correlations with ambient air temperature and soil temperature. Soil moisture, however, only played an important role in affecting the soil respiration rate of C. virgata community while air humidity near the soil surface was significantly correlated with the soil respiration rates of P. australis and L. chinensis communities. The soil salt contents seriously constrained the CO2 dioxide emission, and the soil pH, electrical conductivity (EC), exchangeable sodium percentage (ESP) could explain 87%-91% spatial variations of the soil respiration rate. PMID:24765841

  8. Fate and movement of selenium from drainage sediments disposed onto soil with and without vegetation.

    PubMed

    Bañuelos, G S; Bitterli, C; Schulin, R

    2013-09-01

    Disposal options for salty and selenium-laden agricultural drainage sediments are needed to protect the agricultural ecosystem in Central California. Thus, a 7-year pilot-scale field study evaluated the effects of disposing Se-laden drainage sediment onto soil that was planted with either salado grass (Sporobolus airoides 'salado') or cordgrass (Spartina patens 'Flageo'), or on soil left bare with and without irrigation. Significant decreases in salinity and water-extractable and total soil Se concentrations were observed in all treatments to a depth 30 cm, while water extractable Se and salinity increased most significantly between 30 and 60 cm. Total yields increased over time for both species, while plant Se concentrations were ?10 and 12 mg kg(-1) DM for salado and cordgrass, respectively. The results show that Se and soluble salts disposed of as Se-laden drainage sediment onto light textured soils will significantly migrate to lower depths with or without vegetation. PMID:23714369

  9. Impact of vegetation removal and soil aridation on diurnal temperature range in a semiarid region: Application to the Sahel

    PubMed Central

    Zhou, Liming; Dickinson, Robert E.; Tian, Yuhong; Vose, Russell S.; Dai, Yongjiu

    2007-01-01

    Increased clouds and precipitation normally decrease the diurnal temperature range (DTR) and thus have commonly been offered as explanation for the trend of reduced DTR observed for many land areas over the last several decades. Observations show, however, that the DTR was reduced most in dry regions and especially in the West African Sahel during a period of unprecedented drought. Furthermore, the negative trend of DTR in the Sahel appears to have stopped and may have reversed after the rainfall began to recover. This study develops a hypothesis with climate model sensitivity studies showing that either a reduction in vegetation cover or a reduction in soil emissivity would reduce the DTR by increasing nighttime temperature through increased soil heating and reduced outgoing longwave radiation. Consistent with empirical analyses of observational data, our results suggest that vegetation removal and soil aridation would act to reduce the DTR during periods of drought and human mismanagement over semiarid regions such as the Sahel and to increase the DTR with more rainfall and better human management. Other mechanisms with similar effects on surface energy balance, such as increased nighttime downward longwave radiation due to increased greenhouse gases, aerosols, and clouds, would also be expected to have a larger impact on DTR over drier regions. PMID:17986620

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

    SciTech Connect

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

    2008-03-31

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2007-07-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2008-03-01

    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.

  13. Predicting soil water repellency using hydrophobic organic compounds and their vegetation origin

    NASA Astrophysics Data System (ADS)

    Mao, J.; Nierop, K. G. J.; Rietkerk, M.; Dekker, S. C.

    2015-06-01

    It is widely accepted that soil water repellency (SWR) is mainly caused by plant-derived hydrophobic organic compounds in soils; such hydrophobic compounds are defined as SWR markers. However, the detailed influence of SWR markers on SWR is yet unclear and the knowledge of their original sources is still limited. The aims of this study are to select important SWR markers to predict SWR based on their correlation with SWR and to determine their origin. In our study, sandy soils with different SWR were collected, along with their covering vegetation, i.e. plant leaves/needles and roots. A sequential extraction procedure was applied to the soils to obtain three organic fractions: dichloromethane (DCM)/MeOH soluble fraction (D), DCM/MeOH insoluble fraction of isopropanol/ammonia solution (IPA/NH3) extract (AI) and DCM/MeOH soluble fraction of IPA/NH3 extract (AS), which were subdivided into 10 dominant SWR marker groups: D fatty acid, D alcohol, D alkane, AI fatty acid, AI alcohol, AI ?-hydroxy fatty acid, AI ?,?-dicarboxylic acid, AS fatty acid, AS alcohol and AS ?-hydroxy fatty acid. Waxes and biopolyesters of the vegetation were also sequentially extracted from plants. The soils with higher SWR have significantly higher relative concentrations of AS alcohols. A number of indications suggest that AS alcohols are mainly derived from roots and most likely produced by microbial hydrolysis of biopolyesters (mainly suberins). In addition, the strong correlation between the biomarkers of plant tissues and SWR markers in soils suggests that it is more accurate to predict SWR of topsoils using ester-bound alcohols from roots, and to predict SWR of subsoils using root-derived ?-hydroxy fatty acids and ?,?-dicarboxylic acids. Considering the sandy soils studied here, the relationships we obtained need to be tested for other types of soils. Our analysis indicates that plant roots have a primary role influencing SWR relative to plant leaves.

  14. Herbaceous vegetation productivity, persistence, and metals uptake on a biosolids-amended mine soil

    SciTech Connect

    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

    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.

  15. A fully traits-based approach to modeling global vegetation distribution

    PubMed Central

    van Bodegom, Peter M.; Douma, Jacob C.; Verheijen, Lieneke M.

    2014-01-01

    Dynamic Global Vegetation Models (DGVMs) are indispensable for our understanding of climate change impacts. The application of traits in DGVMs is increasingly refined. However, a comprehensive analysis of the direct impacts of trait variation on global vegetation distribution does not yet exist. Here, we present such analysis as proof of principle. We run regressions of trait observations for leaf mass per area, stem-specific density, and seed mass from a global database against multiple environmental drivers, making use of findings of global trait convergence. This analysis explained up to 52% of the global variation of traits. Global trait maps, generated by coupling the regression equations to gridded soil and climate maps, showed up to orders of magnitude variation in trait values. Subsequently, nine vegetation types were characterized by the trait combinations that they possess using Gaussian mixture density functions. The trait maps were input to these functions to determine global occurrence probabilities for each vegetation type. We prepared vegetation maps, assuming that the most probable (and thus, most suited) vegetation type at each location will be realized. This fully traits-based vegetation map predicted 42% of the observed vegetation distribution correctly. Our results indicate that a major proportion of the predictive ability of DGVMs with respect to vegetation distribution can be attained by three traits alone if traits like stem-specific density and seed mass are included. We envision that our traits-based approach, our observation-driven trait maps, and our vegetation maps may inspire a new generation of powerful traits-based DGVMs. PMID:25225413

  16. [Variation of soil organic carbon under different vegetation types in Karst Mountain areas of Guizhou Province, southwest China].

    PubMed

    Liao, Hong-kai; Long, Jian

    2011-09-01

    This paper studied the variation characteristics of soil organic carbon (SOC) and different particle sizes soil particulate organic carbon (POC) in normal soil and in micro-habitats under different vegetation types in typical Karst mountain areas of southwest Guizhou. Under different vegetation types, the SOC content in normal soil and in micro-habitats was all in the order of bare land < grass < shrub < forest, with the variation range being 7.18-43.42 g x kg(-1) in normal soil and being 6.62-46.47 g x kg(-1) and 9.01-52.07 g x kg(-1) in earth surface and stone pit, respectively. The POC/MOC (mineral-associated organic carbon) ratio under different vegetation types was in the order of bare land < grass < forest < shrub. Under the same vegetation types, the POC/MOC in stone pit was the highest, as compared to that in normal soil and in earth surface. In the process of bare land-grass-shrub-forest, the contents of different particle sizes soil POC increased, while the SOC mainly existed in the forms of sand- and silt organic carbon, indicating that in Karst region, soil carbon sequestration and SOC stability were weak, soil was easily subjected to outside interference and led to organic carbon running off, and thus, soil quality had the risk of decline or degradation. PMID:22126032

  17. 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

    Wade T. Crow; William P. Kustas; John H. Prueger

    2008-01-01

    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

  18. Herbaceous vegetation productivity, persistence, and metals uptake on a biosolids-amended mine soil

    Microsoft Academic Search

    G. K. Evanylo; A. O. Abaye; C. Dundas; C. E. Zipper; R. Lemus; B. Sukkariyah; J. Rockett

    2005-01-01

    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

  19. The impact of motorcycle traffic on soil and vegetation of stabilized coastal dunes, Israel

    Microsoft Academic Search

    P. Kutiel; Z. Eden; H. Zhevelev

    2001-01-01

    This study aimed to assess the response of soil and annual plant vegetation of stabilized coastal dunes in Israel, to varying\\u000a intensities of off-road motorcycle (ORM) traffic, and to assess their resistance and resilience to such a disturbance. A standard\\u000a experimental procedure that included 0, 20, 50, 100 and 200 ORM straight passes and 150 ORM turn passes was used.

  20. Formation, properties, and “ ex situ ” soil decontamination by vegetable oil-based microemulsions

    Microsoft Academic Search

    Marcia Bragato; Omar A. El Seoud

    2003-01-01

    We have investigated soil decontamination by vegetable oil-based fluids. Methyl esters of babassu oil (BME) and the unsaturated\\u000a fraction of palm oil (UPME) were prepared by transesterification of precursor oils. Phase diagrams of each fatty ester\\/water\\/nonionic\\u000a surfactant (Synperonic 91\\/4) were studied as a function of system composition and temperature. Measurements of solution rheology,\\u000a quasi-elastic light scattering, and interfacial tension were

  1. Protein precipitation by tannins in soil organic horizon and vegetation in relation to tree species

    Microsoft Academic Search

    Bartosz Adamczyk; Veikko Kitunen; Aino Smolander

    2008-01-01

    The aim of this study was to compare the concentration of tannins and their capacity to precipitate proteins in the dominant\\u000a species of ground vegetation (Deschampsia flexuosa (L.) Trin., Pleurozium schreberi (Brid.) Mitt., Vaccinium myrtillus (L.), and Vaccinium vitis-idaea (L.)) and in different layers of the soil organic horizon (litter layer—L, fermentation layer—F, humified layer—H) under\\u000a silver birch (Betula pendula

  2. 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...

  3. Understanding Groundwater Uptake by Phreatophytic Vegetation using a System Dynamics Modeling Approach

    NASA Astrophysics Data System (ADS)

    Gou, S.; Miller, G. R.

    2012-12-01

    Modeling root water uptake provides a powerful tool for illustrating the tight linkage of phreatophytic vegetation with spatial and temporal soil water content variation and groundwater level fluctuations. In this study, we develop a new model framework to simulate root water uptake of phreatophytic vegetation using system dynamics approach. The model simulates root water uptake from saturated and unsaturated zones driven by the potential gradients along the groundwater-soil-plant-atmosphere continuum (GSPAC). It incorporates variable soil and plant hydraulic conductivity properties. A new water stress function is introduced; it considers the influence of both soil water and groundwater on phreatophyte water stress. This function is based on the "vulnerability curve" theory that the loss of hydraulic conductance along the soil-plant pathway limits the plant's capability of extracting and transporting water for transpiration. The model calculates energy balance (water potential changes) and water balance (water content changes) in both soil and plant media simultaneously and has the ability to simulate hydraulic redistribution. This model is applied to simulate water uptake of Quercus douglasii (blue oak) in a California savanna; this species has previously been identified as an obligate phreatophyte. The model results show good agreement with the measured ET, soil moisture, and leaf water potential data. The model indicates that the primary water source of blue oak switches from soil water in wet season to groundwater in dry season. In June, July and August, the average groundwater uptake rate is 13 mm/month, which contributes over 90% of dry season transpiration. During the extreme dry period, the rhizosphere resistance increases significantly and becomes the dominant resistance along the GSPAC. Under such conditions, uptake of groundwater becomes more thermodynamically favorable than uptake of soil water. In addition, the model predicts that during the dry season, cavitation will lead to a hydraulic conductivity loss of approximately 85% in the shallow roots, further constraining soil water uptake. The new water stress function shows good performance in simulating daily transpiration with R-squared value of 0.68. The function also reproduces the physiological interactions and feedbacks between transpiration and root and stomatal conductance—root hydraulic conductance loss reduces stomatal conductance and stomatal conductance reduces transpiration rate to regulate plant water potential and prevent plant hydraulic failure. Hydraulic redistribution leads to significant soil water redistribution and promotes over 8% water uptake for annual transpiration. The model illustrates that with the existence of phreatophytes, deep groundwater can hydraulically impact top soil layers through plant water uptake and hydraulic redistribution.

  4. Soil Water Modeling and Remote Sensing

    Microsoft Academic Search

    THOMAS J. JACKSON

    1986-01-01

    Soil water modeling research conducted as part of the AgRISTARS Soil Moisture project was reviewed along with other relevant studies. Research was categorized as follows: reviews of models, development of simulation models, integrating remotely sensed data and models, surface versus profile soil moisture, and estimating soil water properties. This review and evaluation found that some of the major objectives of

  5. Physically Modeling Stream Channel Adjustment to Woody Riparian Vegetation

    NASA Astrophysics Data System (ADS)

    Bennett, S. J.; Alonso, C. V.

    2003-12-01

    Stream restoration designs often use vegetation to promote bank and channel stability, to facilitate point-bar development, and to encourage natural colonization of riparian species. Here we examine the adjustment of an alluvial channel to in-stream and riparian vegetation using a distorted Froude-scale flume model with a movable boundary. A decimeter-scale trapezoidal channel comprised of 0.8-mm diameter sand was systematically vegetated with emergent, rigid dowels (3-mm in diameter) in rectangular and hemispherical patterns with varying vegetation densities while conserving the shape of the zone and the geometry of the vegetal patterns. Alternate sides of the channel were vegetated at the prescribed spacing of equilibrium alternate bars, ca. 5 to 7 times the channel width. Using flow conditions just below the threshold of sediment motion, flow obstruction, deflection, and acceleration caused bed erosion, bank failure, and morphologic channel adjustments that were wholly attributable to the managed plantings. As vegetation density increased, the magnitude and rate of scaled channel adjustment increased, which included increased channel widths, bankline steepening and meandering, and thalweg meandering. As the modeled channel began to meander, the stream bed aggraded and flow depth decreased markedly, creating a continuously connected, inter-reach complex of mid-channel bars. This study demonstrates the utility of using managed vegetations in stream corridor design and meander development, and it provides the practitioner with guidance on the magnitude of channel adjustment as it relates to vegetation density, shape, and spacing.

  6. Use of vegetation index and surface temperature to estimate soil moisture in a semi-arid catchment in Brazil with limited monitoring

    NASA Astrophysics Data System (ADS)

    Rebello, V. P. A.; Cunha, T. M.; Rotunno Filho, O. C.; Barbosa, M. C.; Franklin, M. R.; Lakshmi, V.

    2014-12-01

    During the last two decades, there have been numerous studies using remote sensing to study catchment energy and water balance. A well-known example is the combination of surface temperature (Ts) and the normalized difference vegetation index (NDVI), which can provide information on vegetation and moisture conditions at the land surface. Since the soil moisture is a key variable in hydrological modeling, this information is potentially useful in large watersheds and remote areas in developing countries, where little infrastructure and few resources still make continuous in-situ monitoring of environmental variables a difficult task, as well as in semi arid areas, where the lack of water may represent an obstacle to the regional economic and sustainable development. The basic methodology is to calculate soil moisture indexes by the scatter plots of NDVI and Ts and to analyze the Ts/NDVI slope, in order to estimate temporal patterns of soil moisture. We will utilize the standard vegetation index and surface temperature products from MODIS and NOAA - AVHRR, and the results will be compared with soil moisture derived from a hydrological model (Soil Moisture Accounting Procedure). This work will focus on a 18200 km² semi-arid catchment in Northeastern Brazil.

  7. Impact of spruce forest and grass vegetation cover on soil micromorphology and hydraulic properties of organic matter horizon

    Microsoft Academic Search

    Radka Kodešová; Lenka Pavl?; Vít Kodeš; Anna Žigová; Antonín Nikodem

    2007-01-01

    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

  8. Gravel admix, vegetation, and soil water interactions in protective barriers: Experimental design, construction, and initial conditions

    SciTech Connect

    Waugh, W.J.

    1989-05-01

    The purpose of this study is to measure the interactive effects of gravel admix and greater precipitation on soil water storage and plant abundance. The study is one of many tasks in the Protective Barrier Development Program for the disposal of Hanford defense waste. A factorial field-plot experiment was set up at the site selected as the borrow area for barrier topsoil. Gravel admix, vegetation, and enhanced precipitation treatments were randomly assigned to the plots using a split-split plot design structure. Changes in soil water storage and plant cover were monitored using neutron probe and point intercept methods, respectively. The first-year results suggest that water extraction by plants will offset gravel-caused increases in soil water storage. Near-surface soil water contents were much lower in graveled plots with plants than in nongraveled plots without plants. Large inherent variability in deep soil water storage masked any effects gravel may have had on water content below the root zone. In the future, this source of variation will be removed by differencing monthly data series and testing for changes in soil water storage. Tests of the effects of greater precipitation on soil water storage were inconclusive. A telling test will be possible in the spring of 1988, following the first wet season during which normal precipitation is doubled. 26 refs., 9 figs., 9 tabs.

  9. 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...

  10. Soil Fertility, Yield and Nutrient Contents of Vegetable Crops after 12 Years of Compost or Fertilizer Amendments

    Microsoft Academic Search

    P. R. Warman

    2005-01-01

    A study of compost- versus conventionally-fertilized vegetable plots was conducted for 12 years in a sandy loam soil near Truro, Nova Scotia. The fertility treatments have been applied annually to six rotation plots planted with six to eight different vegetable crops. The composts consist of animal manure, food waste, yard waste and straw or racetrack manure bedding. This paper investigated

  11. Modeling of riparian vegetated buffer strip width and placement

    Microsoft Academic Search

    Young-Fa Lin; Chao-Yuan Lin; Wen-Chieh Chou; Wen-Tzu Lin; Jing-Shyan Tsai; Cho-Fu Wu

    2004-01-01

    This study addressed the suitable width for riparian vegetated buffer strips (RVBS) using topographic analyses, attenuation curves, and an index model. The Chi Chia Wang Stream is susceptible to pollution because of highly saturated hydraulic conductivity and excessive fertilizer use in the nearby cultivated lands. The buffer strip widths calculated from a potassium attenuation curve in the vegetable plot were

  12. Modeling of vegetation dynamics in the Mississippi River deltaic plain

    Microsoft Academic Search

    Marcel Rejmánek; Charles E. Sasser; James G. Gosselink

    1987-01-01

    An analysis was made of vegetation phenomena associated with cyclic river delta building and abandonment in the Mississippi River deltaic plain, Louisiana. Markov models of vegetation succession were completed for the new Atchafalaya delta and for the abandoned Lafourche delta. Transition matrices representing different flood conditions in the Atchafalaya delta (1979–1984) were used separately and in combinations based on long

  13. Spreading topsoil encourages ecological restoration on embankments: soil fertility, microbial activity and vegetation cover.

    PubMed

    Rivera, Desirée; Mejías, Violeta; Jáuregui, Berta M; Costa-Tenorio, Marga; López-Archilla, Ana Isabel; Peco, Begoña

    2014-01-01

    The construction of linear transport infrastructure has severe effects on ecosystem functions and properties, and the restoration of the associated roadslopes contributes to reduce its impact. This restoration is usually approached from the perspective of plant cover regeneration, ignoring plant-soil interactions and the consequences for plant growth. The addition of a 30 cm layer of topsoil is a common practice in roadslope restoration projects to increase vegetation recovery. However topsoil is a scarce resource. This study assesses the effects of topsoil spreading and its depth (10 to 30 cm) on two surrogates of microbial activity (?-glucosidase and phosphatase enzymes activity and soil respiration), and on plant cover, plant species richness and floristic composition of embankment vegetation. The study also evaluates the differences in selected physic-chemical properties related to soil fertility between topsoil and the original embankment substrate. Topsoil was found to have higher values of organic matter (11%), nitrogen (44%), assimilable phosphorous (50%) and silt content (54%) than the original embankment substrate. The topsoil spreading treatment increased microbial activity, and its application increased ?-glucosidase activity (45%), phosphatase activity (57%) and soil respiration (60%). Depth seemed to affect soil respiration, ?-glucosidase and phosphatase activity. Topsoil application also enhanced the species richness of restored embankments in relation to controls. Nevertheless, the depth of the spread topsoil did not significantly affect the resulting plant cover, species richness or floristic composition, suggesting that both depths could have similar effects on short-term recovery of the vegetation cover. A significant implication of these results is that it permits the application of thinner topsoil layers, with major savings in this scarce resource during the subsequent slope restoration work, but the quality of topsoil relative to the original substrate should be previously assessed on a site by site basis. PMID:24984137

  14. Soil warming and CO2 enrichment induce biomass shifts in alpine tree line vegetation.

    PubMed

    Dawes, Melissa A; Philipson, Christopher D; Fonti, Patrick; Bebi, Peter; Hättenschwiler, Stephan; Hagedorn, Frank; Rixen, Christian

    2015-05-01

    Responses of alpine tree line ecosystems to increasing atmospheric CO2 concentrations and global warming are poorly understood. We used an experiment at the Swiss tree line to investigate changes in vegetation biomass after 9 years of free air CO2 enrichment (+200 ppm; 2001-2009) and 6 years of soil warming (+4 °C; 2007-2012). The study contained two key tree line species, Larix decidua and Pinus uncinata, both approximately 40 years old, growing in heath vegetation dominated by dwarf shrubs. In 2012, we harvested and measured biomass of all trees (including root systems), above-ground understorey vegetation and fine roots. Overall, soil warming had clearer effects on plant biomass than CO2 enrichment, and there were no interactive effects between treatments. Total plant biomass increased in warmed plots containing Pinus but not in those with Larix. This response was driven by changes in tree mass (+50%), which contributed an average of 84% (5.7 kg m(-2) ) of total plant mass. Pinus coarse root mass was especially enhanced by warming (+100%), yielding an increased root mass fraction. Elevated CO2 led to an increased relative growth rate of Larix stem basal area but no change in the final biomass of either tree species. Total understorey above-ground mass was not altered by soil warming or elevated CO2 . However, Vaccinium myrtillus mass increased with both treatments, graminoid mass declined with warming, and forb and nonvascular plant (moss and lichen) mass decreased with both treatments. Fine roots showed a substantial reduction under soil warming (-40% for all roots <2 mm in diameter at 0-20 cm soil depth) but no change with CO2 enrichment. Our findings suggest that enhanced overall productivity and shifts in biomass allocation will occur at the tree line, particularly with global warming. However, individual species and functional groups will respond differently to these environmental changes, with consequences for ecosystem structure and functioning. PMID:25471674

  15. Spreading Topsoil Encourages Ecological Restoration on Embankments: Soil Fertility, Microbial Activity and Vegetation Cover

    PubMed Central

    Rivera, Desirée; Mejías, Violeta; Jáuregui, Berta M.; López-Archilla, Ana Isabel; Peco, Begoña

    2014-01-01

    The construction of linear transport infrastructure has severe effects on ecosystem functions and properties, and the restoration of the associated roadslopes contributes to reduce its impact. This restoration is usually approached from the perspective of plant cover regeneration, ignoring plant-soil interactions and the consequences for plant growth. The addition of a 30 cm layer of topsoil is a common practice in roadslope restoration projects to increase vegetation recovery. However topsoil is a scarce resource. This study assesses the effects of topsoil spreading and its depth (10 to 30 cm) on two surrogates of microbial activity (?-glucosidase and phosphatase enzymes activity and soil respiration), and on plant cover, plant species richness and floristic composition of embankment vegetation. The study also evaluates the differences in selected physic-chemical properties related to soil fertility between topsoil and the original embankment substrate. Topsoil was found to have higher values of organic matter (11%), nitrogen (44%), assimilable phosphorous (50%) and silt content (54%) than the original embankment substrate. The topsoil spreading treatment increased microbial activity, and its application increased ?-glucosidase activity (45%), phosphatase activity (57%) and soil respiration (60%). Depth seemed to affect soil respiration, ?-glucosidase and phosphatase activity. Topsoil application also enhanced the species richness of restored embankments in relation to controls. Nevertheless, the depth of the spread topsoil did not significantly affect the resulting plant cover, species richness or floristic composition, suggesting that both depths could have similar effects on short-term recovery of the vegetation cover. A significant implication of these results is that it permits the application of thinner topsoil layers, with major savings in this scarce resource during the subsequent slope restoration work, but the quality of topsoil relative to the original substrate should be previously assessed on a site by site basis. PMID:24984137

  16. Soil versus foliar iodine fertilization as a biofortification strategy for field-grown vegetables

    PubMed Central

    Lawson, Patrick G.; Daum, Diemo; Czauderna, Roman; Meuser, Helmut; Härtling, Joachim W.

    2015-01-01

    Iodine (I) biofortification of vegetables by means of soil and foliar applications was investigated in field experiments on a sandy loam soil. Supply of iodine to the soil in trial plots fertilized with potassium iodide (KI) and potassium iodate directly before planting (0, 1.0, 2.5, 7.5, and 15 kg I ha-1) increased the iodine concentration in the edible plant parts. The highest iodine accumulation levels were observed in the first growing season: In butterhead lettuce and kohlrabi the desired iodine content [50–100 ?g I (100 g FM)-1] was obtained or exceeded at a fertilizer rate of 7.5 kg IO3--I ha-1 without a significant yield reduction or impairment of the marketable quality. In contrast, supplying KI at the same rate resulted in a much lower iodine enrichment and clearly visible growth impairment. Soil applied iodine was phytoavailable only for a short period of time as indicated by a rapid decline of CaCl2-extractable iodine in the top soil. Consequently, long-term effects of a one-time iodine soil fertilization could not be observed. A comparison between the soil and the foliar fertilization revealed a better performance of iodine applied aerially to butterhead lettuce, which reached the desired iodine accumulation in edible plant parts at a fertilizer rate of 0.5 kg I--I ha-1. In contrast, the iodine content in the tuber of sprayed kohlrabi remained far below the targeted range. The results indicate that a sufficient spreading of iodine applied on the edible plant parts is crucial for the efficiency of the foliar approach and leafy vegetables are the more suitable target crops. The low iodine doses needed as well as the easy and inexpensive application may favor the implementation of foliar sprays as the preferred iodine biofortification strategy in practice. PMID:26157445

  17. Anaerobic Soil Disinfestation (ASD) Combined with Soil Solarization as a Methyl Bromide Alternative: Vegetable Crop Performance and Soil Nutrient Dynamics

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil treatment by anaerobic soil disinfestation (ASD) combined with soil solarization can effectively control soilborne plant pathogens and plant-parasitic nematodes in specialty crop production systems. At the same time, research is limited on the impact of soil treatment by ASD + solarization on c...

  18. Simulating the effects of soil organic nitrogen and grazing on arctic tundra vegetation dynamics on the Yamal Peninsula, Russia

    NASA Astrophysics Data System (ADS)

    Yu, Qin; Epstein, Howard; Walker, Donald

    2009-10-01

    Sustainability of tundra vegetation under changing climate on the Yamal Peninsula, northwestern Siberia, home to the world's largest area of reindeer husbandry, is of crucial importance to the local native community. An integrated investigation is needed for better understanding of the effects of soils, climate change and grazing on tundra vegetation in the Yamal region. In this study we applied a nutrient-based plant community model—ArcVeg—to evaluate how two factors (soil organic nitrogen (SON) levels and grazing) interact to affect tundra responses to climate warming across a latitudinal climatic gradient on the Yamal Peninsula. Model simulations were driven by field-collected soil data and expected grazing patterns along the Yamal Arctic Transect (YAT), within bioclimate subzones C (high arctic), D (northern low arctic) and E (southern low arctic). Plant biomass and NPP (net primary productivity) were significantly increased with warmer bioclimate subzones, greater soil nutrient levels and temporal climate warming, while they declined with higher grazing frequency. Temporal climate warming of 2 °C caused an increase of 665 g m-2 in total biomass at the high SON site in subzone E, but only 298 g m-2 at the low SON site. When grazing frequency was also increased, total biomass increased by only 369 g m-2 at the high SON site in contrast to 184 g m-2 at the low SON site in subzone E. Our results suggest that high SON can support greater plant biomass and plant responses to climate warming, while low SON and grazing may limit plant response to climate change. In addition to the first order factors (SON, bioclimate subzones, grazing and temporal climate warming), interactions among these significantly affect plant biomass and productivity in the arctic tundra and should not be ignored in regional scale studies.

  19. Measuring vegetation type, biomass and moisture for integration into fire spread models using hyperspectral and radar remote sensing

    NASA Astrophysics Data System (ADS)

    Dennison, Philip Eugene

    This dissertation investigates remote sensing measures of three fuel properties important for determining fire danger in Southern California chaparral. Measures derived from Airborne Visible Infrared Imaging Spectrometer (AVIRIS) data of the Santa Barbara Front Range and Santa Monica Mountains were used to map vegetation type and were compared to biomass and moisture. Vegetation type, at the species- or genus-level for chaparral, was mapped using a new technique for selecting endmembers for multiple endmember spectral mixture analysis (MESMA). Time series data demonstrated that selected endmembers and map accuracy changed with soil water balance. Accuracy decreased and the expression of senesced vegetation increased as soil water balance changed from surplus to deficit. Potential optical and active microwave measures of vegetation biomass were compared. Equivalent water thickness (EWT), a hyperspectral measure of liquid water absorption, exhibited the strongest relationship with vegetation biomass. A modified normalized difference water index (mNDWI) time series was used to examine temporal changes in vegetation moisture. Parameters of the modeled time series demonstrated correlations with vegetation type, biomass, and elevation. Remote sensing measures of vegetation type and biomass were integrated into a fire spread model. Simulations of the 1996 Calabasas Fire demonstrate the potential utility of these measures for describing regional fire danger.

  20. Interactions of aluminum with forest soils and vegetation: Implications for acid deposition

    SciTech Connect

    Maynard, A.A.

    1989-01-01

    Recent evidence suggests that an important ecological consequence of acidic deposition is increased aluminum mobilization. There is concern that increased aluminum activity may produce toxic effects in forested ecosystems. My studies were concerned with the behavior of pedogenic and added aluminum in soils derived from chemically different parent material. Soil aluminum was related to the aluminum content of the vegetation found growing in the soils. In addition, aluminum levels of forest litter was compared to levels determined 40 years ago. Field, greenhouse, and laboratory investigations were conducted in which the effects of aluminum concentration on germination and early growth was determined. Soils were then used in greenhouse and laboratory studies to establish patterns of soil and plant aluminum behavior with implications to acid deposition. Results show that the amount of aluminum extracted was related to the pH value of the extracting solution and to the chemical characteristics of the soil. Some acid rain solutions extracted measurable amounts of aluminum from selected primary minerals. Germination and early growth of Pinus radiata was controlled by levels of aluminum in the soil or in solution. Field studies indicated that most forest species were sensitive to rising levels of aluminum in the soil. In general, ferns and fern allies were less sensitive to very high levels of aluminum in the soil, continuing to grow when more advanced dicots have disappeared. Aluminum tissue levels of all species were related to the concentration of aluminum in the soil as was the reappearance of species. Aluminum levels in leaf litter have risen at least 50% in the last 40 years. These values were consistent over 3 years. The implications to acid deposition were discussed.

  1. Factors controlling accumulation of soil organic carbon along vegetation succession in a typical karst region in Southwest China.

    PubMed

    Liu, Shujuan; Zhang, Wei; Wang, Kelin; Pan, Fujing; Yang, Shan; Shu, Shiyan

    2015-07-15

    Vegetation succession enhances the accumulation of carbon in the soil. However, little is known about the mechanisms underlying soil organic carbon (SOC) accumulation in different vegetation types in the karst region of Southwest China. The goal of this study was to identify and prioritize the effects of environmental parameters, including soil physico-chemical properties, microbial biomass, enzyme activities, and litter characteristics, on SOC accumulation along a vegetation succession sere (grassland, shrubland, secondary forest, and primary forest) in the karst landscape of Southwest China. Relationships between these parameters and SOC were evaluated by redundancy analysis. The results showed that SOC accumulation was significantly different among vegetation types (P<0.01) and increased with vegetation succession (from 29.10g·kg(-1) in grassland to 73.92g·kg(-1) in primary forest). Soil biochemistry and physical characteristics significantly affected the accumulation of SOC. Soil microbial biomass showed a predominant effect on SOC in each of the four vegetation types. In addition, the soil physical property (especially the silt content) was another controlling factor in the early stages (grassland), and urease activity and saccharase activity were important controlling factors in the early-middle and middle-late stages, respectively. Litter characteristics only showed mild effects on SOC accumulation. Variation partitioning analysis showed that the contribution of sole main factors to SOC variation decreased, while the interaction effect among parameters increased along the succession gradient. PMID:25828412

  2. Remediation of trichloroethylene-contaminated soils by star technology using vegetable oil smoldering.

    PubMed

    Salman, Madiha; Gerhard, Jason I; Major, David W; Pironi, Paolo; Hadden, Rory

    2015-03-21

    Self-sustaining treatment for active remediation (STAR) is an innovative soil remediation approach based on smoldering combustion that has been demonstrated to effectively destroy complex hydrocarbon nonaqueous phase liquids (NAPLs) with minimal energy input. This is the first study to explore the smoldering remediation of sand contaminated by a volatile NAPL (trichloroethylene, TCE) and the first to consider utilizing vegetable oil as supplemental fuel for STAR. Thirty laboratory-scale experiments were conducted to evaluate the relationship between key outcomes (TCE destruction, rate of remediation) to initial conditions (vegetable oil type, oil: TCE mass ratio, neat versus emulsified oils). Several vegetable oils and emulsified vegetable oil formulations were shown to support remediation of TCE via self-sustaining smoldering. A minimum concentration of 14,000 mg/kg canola oil was found to treat sand exhibiting up to 80,000 mg/kg TCE. On average, 75% of the TCE mass was removed due to volatilization. This proof-of-concept study suggests that injection and smoldering of vegetable oil may provide a new alternative for driving volatile contaminants to traditional vapour extraction systems without supplying substantial external energy. PMID:25528233

  3. An investigation of Mesoscale Flows Induced by Vegetation Inhomogeneities Using an Evapotranspiration Model Calibrated Against HAPEX-MOBILHY Data

    Microsoft Academic Search

    Jean-Pierre Pinty; Patrick Mascart; Evelyne Richard; Robert Rosset

    1989-01-01

    Many recent studies have suggested that heterogeneities in soil properties or vegetation characteristics many trigger mesoscale circulations in planetary boundary layer (PBL). Unfortunately, these flows appear to be very sensitive to the choice of the model characteristics and therefore require a careful calibration of the parameterization representing the vegetation\\/atmosphere interface.In this paper, the micrometeorological data from the HAPEX-MOBILHY field experiment

  4. How sedge meadow soils, microtopography, and vegetation respond to sedimentation

    USGS Publications Warehouse

    Werner, K.J.; Zedler, Joy B.

    2002-01-01

    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.

  5. Influences of soil moisture and vegetation on convective precipitation forecasts

    E-print Network

    Robock, Alan

    on convective available potential energy and moist enthalpy nearly canceled each other out, resulting model and found increases in precipitation and decreases in temperatures over a 10 year period when

  6. The assessments of uncertainties in global vegetation and soil carbon projections in ISI-MIP study

    NASA Astrophysics Data System (ADS)

    Nishina, K.; Ito, A.; Beerling, D.; Cadule, P.; Ciais, P.; Clark, D. B.; Falloon, P.; Friend, A. D.; Kahana, R.; Kato, E.; Keribin, R. M.; Lucht, W.; Lomas, M. R.; Rademacher, T.; Pavlick, R.; Schaphoff, S.; Vuichard, N.; Warszawski, L.; Yokohata, T.

    2013-12-01

    Temperature and precipitation are critical factors in determining the feedback of terrestrial ecosystems to atmospheric CO2. However, the changes in temperature and precipitation in the future climate have large uncertainty both spatially and temporally even at the same radiative forcing levels. This difference in spatial and temporal patterns of climate change among model projections could affect the global C budget of terrestrial ecosystems. In this study, we examined the global soil organic carbon (SOC) and vegetation carbon (VegC) stock dynamics estimated by 6 ecosystem models obtained from the Inter-Sectoral Impact Model Inter-comparison Project (ISI-MIP). Simulation results using 5 global climate models (GCMs) under forced 4 Representative Concentration Pathway scenarios (RCPs) were used. We aimed at exploring the uncertainties in the future carbon budget projected by current ecosystem models. To clarify which of the 3 components (emission scenarios, climate projections, and biome models) has the largest contribution to estimation uncertainty, we applied wavelet clustering to the time-series data of global C stock simulated under 4 RCP scenarios for all GCMs. This cluster analysis procedure enabled us to consider the variability and trend in the time-series domains and to cope with aperiodic components, noise, and transient dynamics. During the projection period (2000-2099), the estimated changes in the global VegC stock for all GCM projections ranged from -20 Pg-C to 200 Pg-C, and corresponding changes in the global SOC stock ranged from -195 Pg-C to 471 Pg-C. The clustering wavelet spectra of SOC time-series data revealed that the 70 simulations were classified into 5 major groups. We focused on these 5 clusters, which mostly of biome models rather than RCPs and GCMs. Considering results of each biome model, the RCPs appropriately differentiated the clusters between the lowest and highest emission scenario. By combining RCP scenarios, GCM climates, and biome models, we found that uncertainties in the global SOC and VegC projection caused by biome models were greater than those caused by driving scenarios, i.e., RCPs and GCMs. The uncertainties associated with the SOC projections are significantly high and it was estimated that global SOC would act as either CO2 sources and or sinks by 2099, depending on biome models used, even though these models reasonably captured similar historical VegC and SOC trends.

  7. Effects of various uranium leaching procedures on soil: Short-term vegetation growth and physiology. Progress report, April 1994

    SciTech Connect

    Edwards, N.T.

    1994-08-01

    Significant volumes of soil containing elevated levels of uranium exist in the eastern United States. The contamination resulted from the development of the nuclear industry in the United States requiring a large variety of uranium products. The contaminated soil poses a collection and disposal problem of a magnitude that justifies the development of decontamination methods. Consequently, the Department of Energy (DOE) Office of Technology Development formed the Uranium Soils Integrated Demonstration (USID) program to address the problem. The fundamental goal of the USID task group has been the selective extraction/leaching or removal of uranium from soil faster, cheaper, and safer than what can be done using current conventional technologies. The objective is to selectively remove uranium from soil without seriously degrading the soil`s physicochemical characteristics and without generating waste that is difficult to manage and/or dispose of. However, procedures developed for removing uranium from contaminated soil have involved harsh chemical treatments that affect the physicochemical properties of the soil. The questions are (1) are the changes in soil properties severe enough to destroy the soil`s capacity to support and sustain vegetation growth and survival? and (2) what amendments might be made to the leached soil to return it to a reasonable vegetation production capacity? This study examines the vegetation-support capacity of soil that had been chemically leached to remove uranium. The approach is to conduct short-term germination and phytotoxicity tests for evaluating soils after they are subjected to various leaching procedures followed by longer term pot studies on successfully leached soils that show the greatest capacity to support plant growth. This report details the results from germination and short-term phytotoxicity testing of soils that underwent a variety of leaching procedures at the bench scale at ORNL and at the pilot plant at Fernald.

  8. DEM modelling, vegetation characterization and mapping of aspen parkland rangeland using LIDAR data

    Microsoft Academic Search

    Guangquan Su

    2004-01-01

    Detailed geographic information system (GIS) studies on plant ecology, animal behavior and soil hydrologic characteristics across spatially complex landscapes require an accurate digital elevation model (DEM). Following interpolation of last return LIDAR data and creation of a LIDAR-derived DEM, a series of 260 points, stratified by vegetation type, slope gradient and off-nadir distance, were ground-truthed using a total laser station,

  9. N mineralization and nitrate leaching from vegetable crop residues under field conditions: a model evaluation

    Microsoft Academic Search

    S. de Neve; G. Hofman

    1998-01-01

    Six different vegetable crop residues were incorporated in the field and N mineralization from the residues and from an unamended plot was followed over 4months by periodically monitoring mineral N contents of the soil. The crop residues were also fractionated according to a modified Stevenson chemical fractionation. Nitrogen mineralization parameters of the first order kinetic model N(t)=NA(1?e?kt) were derived from

  10. Sensitivity and feedbacks associated with vegetation-related land surface parameters in a general circulation model

    SciTech Connect

    Lofgren, B.M.

    1993-01-01

    A series of general circulation model (GCM) experiments were run to investigate the effects on climate of surface albedo, surface roughness, and field capacity. When decreased surface albedo is prescribed, at low latitudes, precipitation and soil moisture are increased, because of the increased upward motion resulting from additional atmospheric heating. At mid-latitudes, the precipitation is insensitive to decreased surface albedo, but soil moisture is decreased. A prescribed decrease in land surface roughness causes a general decrease in evaporation from land and water vapor flux convergence over land, and consequently also in precipitation. Land surface albedo was interactive with the GCM climate, using the climate to determine the vegetative cover. When compared to a control case with constant surface albedo over all land, tropical rainforests have increased precipitation and soil moisture. This promotes more growth of vegetation, causing positive feedback within the system. Subtropical deserts have decreased precipitation and soil moisture, and there is evidence of a southward shift in the Sahara. Midlatitudes have little response in precipitation, but have soil moisture responses which imply negative feedback. When surface roughness is interactively predicted, low-latitude forests have increased precipitation, primarily along coasts where there are shoreward winds. This leads to increased vegetation and greater surface roughness, making it a positive feedback. At midlatitudes the roughness of the forests causes enhanced Ekman convergence, resulting in increased precipitation. Neither the pattern changes in precipitation nor of changes in soil moisture as a fraction of field capacity is clearly correlated to the distribution of initially predicted field capacity. When all three parameters are made interactive simultaneously, the precipitation and soil moisture responses are approximately the sum of the responses to individual parameters.

  11. Trends in soil-vegetation dynamics in burned Mediterranean pine forests: the effects of soil properties

    Microsoft Academic Search

    L. Wittenberg; D. Malkinson

    2009-01-01

    Fire can impact a variety of soil physical and chemical properties. These changes may result, given the fire severity and the local conditions, in decreased infiltration and increased runoff and erosion rates. Most of these changes are caused by complex interactions among eco-geomorphic processes which affect, in turn, the rehabilitation dynamics of the soil and the regeneration of the burnt

  12. Predicting soil water repellency by hydrophobic organic compounds and their vegetation origin

    NASA Astrophysics Data System (ADS)

    Mao, J.; Nierop, K. G. J.; Rietkerk, M.; Dekker, S. C.

    2015-02-01

    It is widely accepted that soil water repellency (SWR) is mainly caused by plant-derived hydrophobic organic compounds in soils; such hydrophobic compounds are defined as SWR-markers. However, the detailed influence of SWR-markers on SWR is yet unclear and the knowledge of their original sources is still limited. The aims of this study are to select important SWR-markers to predict SWR based on their correlation with SWR and to determine their origin. In our study, sandy soils with different SWR were collected, along with their covering vegetation, i.e. plant leaves/needles and roots. A sequential extraction procedure was applied to the soils to obtain three organic fractions: DCM / MeOH soluble fraction (D), DCM / MeOH insoluble fraction of IPA / NH3 extract (AI) and DCM / MeOH soluble fraction of IPA / NH3 extract (AS), which were subdivided into ten dominant SWR-marker groups: (D) fatty acid, (D) alcohol, (D) alkane, (AI) fatty acid, (AI) alcohol, (AI) ?-hydroxy fatty acid, (AI) ?, ?-dicarboxylic acid, (AS) fatty acid, (AS) alcohol and (AS) ?-hydroxy fatty acid. Waxes and biopolyesters of the vegetation were also sequentially extracted from plants. In short, the soils with higher SWR have significantly higher relative concentrations of (AS) alcohols. A number of indications suggest that (AS) alcohols are mainly derived from roots and most likely produced by microbial hydrolysis of biopolyesters/suberins. In addition, the strong correlation between the biomarkers of plant tissues and SWR-markers in soils suggests that it is more accurate to predict SWR of topsoils using ester-bound alcohols from roots, and to predict SWR of subsoils using root-derived ?-hydroxy fatty acids and ?, ?-dicarboxylic acids. Our analysis indicates that plant roots have a primary role influencing SWR relative to plant leaves.

  13. Particulate organic carbon export from soil and vegetation in temperate mountain regions

    NASA Astrophysics Data System (ADS)

    Smith, J. C.; Hovius, N.; Galy, A.; Tye, A.; Turowski, J.

    2012-04-01

    In assessing the significance of terrestrial particulate organic carbon (POC) export in the global carbon cycle, it is essential to be able to predict the POC yield and its make-up (broadly, fossil versus non-fossil) from any given setting. Because mountains vastly dominate the physical erosion load, an understanding of the processes operating in mountains of different kinds, and what controls them, is necessary. In particular, the dynamics of POC harvest in temperate forested uplands are poorly constrained, despite the large area covered by these zones. C and N concentration and isotopic composition data (for both riverine suspended sediment and carbon stores) are presented from two contrasting temperate mountain regions with vast stocks of soil organic carbon. In the northern Swiss Alps, as discharge increases, POC is initially diluted by lithic material through in-channel clearing, but beyond a threshold POC is added. This happens under moderate flow conditions when hillslopes are activated and rain- induced overland flow delivers soil POC to channels. As a result, the proportion of non-fossil POC increases significantly as discharge and suspended sediment load increase. In contrast to the Swiss Alps, overland flow occurs rarely in the Oregon Cascades and Coast Range. There, hillslope soil is decoupled from the channel, due largely to riparian vegetation that both prevents extensive mobilisation and traps sediment before it reaches the stream. Where channels are aggrading, there is no other input mechanism for soil or bedrock, resulting in very low total sediment and POC yields (and correspondingly high POC concentrations). In the Coast Range, with largely sedimentary rather than volcanic substrate, there is some evidence for hillslope soil mobilisation, but not (under moderate meteorological conditions) on the scale observed in Switzerland. Instead, nearly all POC exported comes from vegetation. Initial dilution of POC through in-channel clearing is still evident, and without subsequent activation of the soil reservoir, Oregon's POC export (per unit area) is around an order of magnitude less than the Swiss system.

  14. Model for the genesis of coastal dune fields with vegetation

    NASA Astrophysics Data System (ADS)

    de M. Luna, Marco C. M.; Parteli, Eric J. R.; Durán, Orencio; Herrmann, Hans J.

    2011-06-01

    Vegetation greatly affects the formation and dynamics of dune fields in coastal areas. In the present work, we use dune modeling in order to investigate the genesis and early development stages of coastal dune fields in the presence of vegetation. The model, which consists of a set of coupled equations for the turbulent wind field over the landscape, the saltation flux and the growth of vegetation cover on the surface, is applied to calculate the evolution of a sand patch placed upwind of a vegetated terrain and submitted to unidirectional wind and constant sand influx. Different dune morphologies are obtained, depending on the characteristic rate of vegetation growth relative to wind strength: barchans, transverse dunes with trailing ridges, parabolic dunes and vegetated, alongshore sand barriers or foredunes. The existence of a vegetation-free backshore is found to be important for the nucleation timescale of coastal dune generations. The role of the sand influx and of the maximum vegetation cover density for the dune shape is also discussed.

  15. Vegetation monitoring and estimation of evapotranspiration using remote sensing-based models in heterogeneous areas with patchy natural vegetation and crops

    NASA Astrophysics Data System (ADS)

    Carpintero, Elisabet; Andreu, Ana; Gonzalez-Dugo, Maria P.

    2015-04-01

    The integration of remotely sensed data into models for estimating evapotranspiration (ET) has increased significantly in recent years, allowing the extension of these models application from point to regional scale. Remote sensors provide distributed information about the status of vegetation and allow for a regular monitoring of water consumption. Currently, there are two types of approaches for estimating ET based either on the soil water balance, or surface energy balance. The first one uses the reflectance of vegetated surfaces in the visible and near infrared regions of the electromagnetic spectrum (VIS / NIR) to characterize the vegetation and its role in the water balance (Gonzalez-Dugo and Mateos, 2008). On the other hand, thermal-based energy balance models use the radiometric surface temperature registered by the sensor on thermal infrared (TIR) bands as the primary boundary condition for estimating ET (Kustas and Norman, 1996). The aim of this work is to carry out, using Landsat-8 satellite images, a continuous monitoring of growth and evapotranspiration of the different vegetation types, both natural and cultivated, in a region located in Southern Spain during the season August 2013 / September 2014. The region, with about 13800 ha, is marked by strong contrasts in the physical environment, with significant altitudinal gradient combined with a great variety of soil types and vegetation. It is characterized by a variation of grassland, scrubs, conifers, oaks and irrigated crops. In this work, a daily soil water balance has been applied using the vegetation index-basal crop coefficient approach (RSWB). This model is based on FAO-56 methodology (Allen et al., 1998), which determines the evapotranspiration of vegetation with the concepts of crop coefficient and reference ET. The crop coefficient accounts for the influence of the plants on the evapotranspiration, considering the effect of changes in canopy biophysical properties throughout the growth cycle. It has been derived using the dual method that separates the crop transpiration from soil surface evaporation. Combining it with the spectral response of the surface provided by satellite images, a distributed basal crop coefficient is derived, which determines vegetation transpiration. There are many applications that successfully validated this approach, both in agricultural areas and heterogeneous coverage (Padilla et al., 2011; Campos et al., 2013). In this application, local meteorological data and soil properties have been used, providing daily and distributed evapotranspiration information at 30 m pixel scale during the studied period. These results have been contrasted with that obtained from the application of a two-source energy balance model (TSEB) for the days with available thermal data. The TSEB model separates the soil and canopy contributions to the radiative temperature and to the exchange of surface energy fluxes. This model has proven to be robust in heterogeneous and incomplete covers (Timmermans et al., 2007; González-Dugo et al., 2009). The results of the comparison are used to validate the RSWB under different soil and vegetation conditions and to explore new possible applications of this approach.

  16. Spatial estimation of antibiotic residues in surface soils in a typical intensive vegetable cultivation area in China.

    PubMed

    Xie, Yun-feng; Li, Xue-Wen; Wang, Jin-Feng; Christakos, George; Hu, Mao-Gui; An, Li-Hong; Li, Fa-Sheng

    2012-07-15

    Antibiotic residues in surface soils can lead to serious health risks and ecological hazards. Spatial mean concentration of antibiotic residues in the soil is the most important indicator of a region's environmental risk to antibiotic residues. Considerable estimation error would lead to an inefficient strategy of pollution control that happens when sample size is small and the estimation model does not match the spatial features of the object to be surveyed. On the basis of the available datasets, it was found that the distribution of antibiotics residue in soil follows a spatial stratification pattern. Accordingly, we used a new spatial estimation method called Mean of Surface with Non-homogeneity (MSN) to estimate antibiotic concentrations in surface soil of the Shandong Province, an important vegetable growing region in China. The standard error of the mean estimates obtained by MSN was significantly smaller (by about 1.02-6.82 ?g/kg) than the estimation errors produced by three mainstream methods, simple arithmetic estimation (2.9-11.8 ?g/kg), stratified estimation (2.5-10.6 ?g/kg) and ordinary kriging estimation (2.2-8.2 ?g/kg). PMID:22634559

  17. Coastal vegetation invasion increases greenhouse gas emission from wetland soils but also increases soil carbon accumulation.

    PubMed

    Chen, Yaping; Chen, Guangcheng; Ye, Yong

    2015-09-01

    Soil properties and soil-atmosphere fluxes of CO2, CH4 and N2O from four coastal wetlands were studied throughout the year, namely, native Kandelia obovata mangrove forest vs. exotic Sonneratia apetala mangrove forest, and native Cyperus malaccensis salt marsh vs. exotic Spartina alterniflora salt marsh. Soils of the four wetlands were all net sources of greenhouse gases while Sonneratia forest contributed the most with a total soil-atmosphere CO2-equivalent flux of 137.27mgCO2m(-2)h(-1), which is 69.23%, 99.75% and 44.56% higher than that of Kandelia, Cyperus and Spartina, respectively. The high underground biomass and distinctive root structure of Sonneratia might be responsible for its high greenhouse gas emission from the soil. Soils in Spartina marsh emitted the second largest amount of total greenhouse gases but it ranked first in emitting trace greenhouse gases. Annual average CH4 and N2O fluxes from Spartina soil were 13.77 and 1.14?molm(-2)h(-1), respectively, which are 2.08 and 1.46 times that of Kandelia, 1.03 and 1.15 times of Sonneratia, and 1.74 and 1.02 times of Cyperus, respectively. Spartina has longer growing season and higher productivity than native marshes which might increase greenhouse gas emission in cold seasons. Exotic wetland soils had higher carbon stock as compared to their respective native counterparts but their carbon stocks were offset by a larger proportion because of their higher greenhouse gas emissions. Annual total soil-atmosphere fluxes of greenhouse gases reduced soil carbon burial benefits by 8.1%, 9.5%, 6.4% and 7.2% for Kandelia, Sonneratia, Cyperus and Spartina, respectively, which narrowed down the gaps in net soil carbon stock between native and exotic wetlands. The results indicated that the invasion of exotic wetland plants might convert local coastal soils into a considerable atmospheric source of greenhouse gases although they at the same time increase soil carbon accumulation. PMID:25918889

  18. Modeling vegetation reflectance from satellite and in-situ monitoring data

    NASA Astrophysics Data System (ADS)

    Zoran, Maria; Florin Zoran, Liviu; Ionescu Golovanov, Carmen; Dida, Adrian

    2010-05-01

    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.

  19. VARIABILITY IN SOILS AND VEGETATION ASSOCIATED WITH HARVESTER ANT (POGONOMYRMEX RUGOSUS) NESTS ON A CHIHUAHUAN DESERT WATERSHED

    EPA Science Inventory

    The effects of harvester ant (Pogonomyrmex rugosus) nests on the density and cover of spring annual plants and on soil characteristics were measured at three locations characterized by different soils and dominant vegetation on a desert watershed. There were few differences in ve...

  20. Composition and Diversity of Soil Microbial Communities Following Vegetation Change from Grassland to Woodland: An Assessment Using Molecular Methods

    E-print Network

    Composition and Diversity of Soil Microbial Communities Following Vegetation Change from Grassland that subtropical thorn woodlands dominated by N-fixing tree legumes have largely replaced grasslands, resulting the composition and function of soil microbial communities. OBJECTIVE To assess the impact of grassland

  1. Representing the effects of alpine grassland vegetation cover on the simulation of soil thermal dynamics by ecosystem

    E-print Network

    Ickert-Bond, Steffi

    Representing the effects of alpine grassland vegetation cover on the simulation of soil thermal and atmospheric factors on the estimation of soil surface temperature for alpine grassland ecosystems has the potential to substantially improve our understanding of the vulnerability of alpine grassland

  2. Nutrient Availability in Rangeland Soils: Influence of Prescribed Burning, Herbaceous Vegetation Removal, Overseeding with Bromus Tectorum, Season, and Elevation

    Microsoft Academic Search

    R. R. Blank; J. Chambers; B. Roundy; A. Whittaker

    2007-01-01

    Soil nutrient availability influences plant invasions. Resin capsules were used to examine soil nutrient bioavailability along 2 sagebrush-grassland elevation transects in the east Tintic Range (Utah) and Shoshone Range (Nevada). In the fall of 2001, treatments were applied to 3 replicate plots at each site, which included prescribed burning, herbaceous vegetation removal, and controls. Cheatgrass (Bromus tectorum L.) was overseeded

  3. The effect of recreational impacts on soil and vegetation of stabilised Coastal Dunes in the Sharon Park, Israel

    Microsoft Academic Search

    P Kutiel; H Zhevelev; R Harrison

    1999-01-01

    Coastal sand dunes are considered among the most susceptible habitats to recreational use. The aim of this study was to monitor the impact of visitor use on soil and annual plants on long-established trails in the stabilised coastal dunes of the Sharon Park, Israel. The results indicate that:1.The vegetation cover, height and species richness and diversity, as well as soil

  4. Measuring sap flow, and other plant physiological conditions across a soil salinity gradient in the lower Colorado River at Cibola National Wildlife Refuge: Vegetation and soil physiology linkages with microwave dielectric constant

    NASA Astrophysics Data System (ADS)

    McDonald, K. C.; Lasne, Y.; Schroeder, R.; Morino, K.; Hultine, K. R.; Nagler, P. L.

    2009-12-01

    We used ground measurements to examine stand structure and evapotranspiration of Tamarix in the Cibola National Wildlife Refuge (CNWR) on the Lower Colorado River. Three Tamarix study sites were established at different distances from the Colorado River on a river terrace in the CNWR. The sites were chosen from aerial photographs to represent typical dense stands of Tamarix within the CNWR. The sites were representative of differing saline environments, with each having ground water with distinct salt concentration levels. Wells were established at the site to establish depth to water and the salinity concentration within the ground water. We monitored xylem sap flow within each of the three stands. In addition we measured leaf area index to characterize canopy structure. We compared ET, foliage density, depth to water, and salinity among the Tamarix sites to examine stand-level variability driven by the variations in salinity. We supplemented these collections with measurements to characterize soil and vegetation microwave dielectric properties and their relationship to physiologic parameters. The dielectric properties of a material describe the interaction of an electric field with the material. Previous field experiments have demonstrated that varying degrees of correlation exist between vegetation dielectric properties and tree canopy water status. Temporal variation of the dielectric constant of woody plant tissue may result from changes in water status (e.g., water content) and chemical composition, albeit to varying degrees of sensitivity. The varying amount of ground water salinity at CNWR offers a unique opportunity to examine the relationship between vegetation and soil dielectric constant as related to vegetation ecophysiology. A field portable vector network analyzer is used to measure the microwave dielectric spectrum of the soil and vegetation Combined with measurements of vegetation xylem sap flux and soil chemistry, these measurements allow examination of vegetation physiology as related to soil moisture and chemistry, and examination of the corresponding relationship to radar backscatter. Radar backscatter models and microwave dielectric constant models are used to infer the correspondence between the ground measurements and the radar backscatter. This analysis framework allows examination of soil chemistry gradient and the corresponding effect on the vegetation physiology. Portions of this work were carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

  5. Examination of Soil Moisture Retrieval Using SIR-C Radar Data and a Distributed Hydrological Model

    NASA Technical Reports Server (NTRS)

    Hsu, A. Y.; ONeill, P. E.; Wood, E. F.; Zion, M.

    1997-01-01

    A major objective of soil moisture-related hydrological-research during NASA's SIR-C/X-SAR mission was to determine and compare soil moisture patterns within humid watersheds using SAR data, ground-based measurements, and hydrologic modeling. Currently available soil moisture-inversion methods using active microwave data are only accurate when applied to bare and slightly vegetated surfaces. Moreover, as the surface dries down, the number of pixels that can provide estimated soil moisture by these radar inversion methods decreases, leading to less accuracy and, confidence in the retrieved soil moisture fields at the watershed scale. The impact of these errors in microwave- derived soil moisture on hydrological modeling of vegetated watersheds has yet to be addressed. In this study a coupled water and energy balance model operating within a topographic framework is used to predict surface soil moisture for both bare and vegetated areas. In the first model run, the hydrological model is initialized using a standard baseflow approach, while in the second model run, soil moisture values derived from SIR-C radar data are used for initialization. The results, which compare favorably with ground measurements, demonstrate the utility of combining radar-derived surface soil moisture information with basin-scale hydrological modeling.

  6. Potential effects of large linear pipeline construction on soil and vegetation in ecologically fragile regions.

    PubMed

    Xiao, Jun; Wang, Ya-Feng; Shi, Peng; Yang, Lei; Chen, Li-Ding

    2014-11-01

    Long-distance pipeline construction results in marked human disturbance of the regional ecosystem and brings into question the safety of pipeline construction with respect to the environment. Thus, the direct environmental impact and proper handling of such large projects have received much attention. The potential environmental effects, however, have not been fully addressed, particularly for large linear pipeline projects, and the threshold of such effects is unclear. In this study, two typical eco-fragile areas in western China, where large linear construction projects have been conducted, were chosen as the case study areas. Soil quality indices (SQI) and vegetation indices (VI), representing the most important potential effects, were used to analyze the scope of the effect of large pipeline construction on the surrounding environment. These two indices in different buffer zones along the pipeline were compared against the background values. The analysis resulted in three main findings. First, pipeline construction continues to influence the nearby eco-environment even after a 4-year recovery period. During this period, the effect on vegetation due to pipeline construction reaches 300 m beyond the working area, and is much larger in distance than the effect on soil, which is mainly confined to within 30 m either side of the pipeline, indicating that vegetation is more sensitive than soil to this type of human disturbance. However, the effect may not reach beyond 500 m from the pipeline. Second, the scope of the effect in terms of distance on vegetation may also be determined by the frequency of disturbance and the intensity of the pipeline construction. The greater the number of pipelines in an area, the higher the construction intensity and the more frequent the disturbance. Frequent disturbance may expand the effect on vegetation on both sides of the pipeline, but not on soil quality. Third, the construction may eliminate the stable, resident plant community. During the recovery period, the plant community in the work area of the pipeline is replaced by some species that are rare or uncommon in the resident plant community because of human disturbance, thereby increasing the plant diversity in the work area. In terms of plant succession, the duration of the recovery period has a direct effect on the composition and structure of the plant community. The findings provide a theoretical basis and scientific foundation for improving the environmental impact assessment (EIA) of oil and gas pipeline construction as it pertains to the desert steppe ecosystem, and provide a reference point for recovery and management of the eco-environment during the pipeline construction period. PMID:25112841

  7. Improving the dynamics of northern vegetation in the ORCHIDEE ecosystem model

    NASA Astrophysics Data System (ADS)

    Zhu, D.; Peng, S. S.; Ciais, P.; Viovy, N.; Druel, A.; Kageyama, M.; Krinner, G.; Peylin, P.; Ottlé, C.; Piao, S. L.; Poulter, B.; Schepaschenko, D.; Shvidenko, A.

    2015-02-01

    Processes that describe the distribution of vegetation and ecosystem succession after disturbance are an important component of dynamic global vegetation models (DGVMs). The vegetation dynamics module (ORC-VD) within the process-based ecosystem model ORCHIDEE (Organizing Carbon and Hydrology in Dynamic Ecosystems) has not been updated and evaluated since many years and does not match the progress in modeling the rest of the physical and biogeochemical processes. Therefore, ORC-VD is known to produce unrealistic results. This study presents a new parameterization of ORC-VD for mid-to-high latitude regions in the Northern Hemisphere, including processes that influence the existence, mortality and competition between tree functional types. A new set of metrics is also proposed to quantify the performance of ORC-VD, using up to five different datasets of satellite land cover, forest biomass from remote sensing and inventories, a data-driven estimate of gross primary productivity (GPP) and two gridded datasets of soil organic carbon content. The scoring of ORC-VD derived from these metrics integrates uncertainties in the observational datasets. This multi-dataset evaluation framework is a generic method that could be applied to the evaluation of other DGVM models. The results of the original ORC-VD published in 2005 for mid-to-high latitudes and of the new parameterization are evaluated against the above-described datasets. Significant improvements were found in the modeling of the distribution of tree functional types north of 40° N. Three additional sensitivity runs were carried out to separate the impact of different processes or drivers on simulated vegetation distribution, including soil freezing which limits net primary production through soil moisture availability in the root zone, elevated CO2 concentration since 1850, and the return frequency of cold climate extremes causing tree mortality during the spin-up phase of the model.

  8. Effect of vegetation of transgenic Bt rice lines and their straw amendment on soil enzymes, respiration, functional diversity and community structure of soil microorganisms under field conditions.

    PubMed

    Fang, Hua; Dong, Bin; Yan, Hu; Tang, Feifan; Wang, Baichuan; Yu, Yunlong

    2012-01-01

    With the development of transgenic crops, there is an increasing concern about the possible adverse effects of their vegetation and residues on soil environmental quality. This study was carried out to evaluate the possible effects of the vegetation of transgenic Bt rice lines Huachi B6 (HC) and TT51 (TT) followed by the return of their straw to the soil on soil enzymes (catalase, urease, neutral phosphatase and invertase), anaerobic respiration activity, microbial utilization of carbon substrates and community structure, under field conditions. The results indicated that the vegetation of the two transgenic rice lines (HC and TT) and return of their straw had few adverse effects on soil enzymes and anaerobic respiration activity compared to their parent and distant parent, although some transient differences were observed. The vegetation and subsequent straw amendment of Bt rice HC and TT did not appear to have a harmful effect on the richness, evenness and community structure of soil microorganisms. No different pattern of impact due to plant species was found between HC and TT. It could be concluded that the vegetation of transgenic Bt rice lines and the return of their straw as organic fertilizer may not alter soil microbe-mediated functions. PMID:23513447

  9. Vegetation associated with the major soils and reclamation areas on the Navajo Mine, New Mexico

    SciTech Connect

    Buchanan, B.A.; Wood, M.K. [New Mexico State Univ., Las Cruces, NM (United States); Ruzzo, W. [BHP - Utah International Inc., Fruitland, NM (United States)

    1990-12-31

    Mine-land reclamation success is usually measured by comparing reclaimed areas to be the pre-mined or native conditions. Establishing standards of reclamation is made more difficult when the native conditions are extremely variable as for the Navajo Mine. The Navajo mine lease has annual grazing capacities ranging from 12 hectares (30 acres) to 80 hectares (200 acres) per sheep. The objective of this research was to determine the vegetal characteristics combining the most extensive or most productive native soil types on the Navajo Lease. Then to compare these data using weighted means (based on percent area) to the vegetal characteristics of topdressed and non-topdressed reclamation plots. Some native areas have high cover, shrub density and phytomass. However, these vegetal characteristics are lower for the average native condition than the average for either the topdressed or non-topdressed reclamation plots. The weighted mean of the native area is low because of the extensive amount (>65%) of badland and natrargid type soils. These two mapping units have extremely low cover, shrub density and phytomass. Reclaimed plots without topdressing have higher cover and phytomass than topdressed reclamation plots. This is because of the high schrub density. However, the topdressed reclamation areas produce more perennial forbs and grasses than non topdressed plots. This is considered to be more desirable for reclamation success.

  10. A LANDSAT study of ephemeral and perennial rangeland vegetation and soils

    NASA Technical Reports Server (NTRS)

    Bentley, R. G., Jr. (principal investigator); Salmon-Drexler, B. C.; Bonner, W. J.; Vincent, R. K.

    1976-01-01

    The author has identified the following significant results. Several methods of computer processing were applied to LANDSAT data for mapping vegetation characteristics of perennial rangeland in Montana and ephemeral rangeland in Arizona. The choice of optimal processing technique was dependent on prescribed mapping and site condition. Single channel level slicing and ratioing of channels were used for simple enhancement. Predictive models for mapping percent vegetation cover based on data from field spectra and LANDSAT data were generated by multiple linear regression of six unique LANDSAT spectral ratios. Ratio gating logic and maximum likelihood classification were applied successfully to recognize plant communities in Montana. Maximum likelihood classification did little to improve recognition of terrain features when compared to a single channel density slice in sparsely vegetated Arizona. LANDSAT was found to be more sensitive to differences between plant communities based on percentages of vigorous vegetation than to actual physical or spectral differences among plant species.

  11. Modelling in situ enzyme potential of soils: a tool to predict soil respiration from agricultural fields

    NASA Astrophysics Data System (ADS)

    Shahbaz Ali, Rana; Poll, Christian; Demyan, Scott; Nkwain Funkuin, Yvonne; Ingwersen, Joachim; Wizemann, Hans-Dieter; Kandeler, Ellen

    2014-05-01

    The fate of soil organic carbon (SOC) is one of the largest uncertainties in predicting future climate and terrestrial ecosystem functions. Extra-cellular enzymes, produced by microorganisms, perform the very first step in SOC degradation and serve as key components in global carbon cycling. Very little information is available about the seasonal variation in the temperature sensitivity of soil enzymes. Here we aim to model in situ enzyme potentials involved in the degradation of either labile or recalcitrant organic compounds to understand the temporal variability of degradation processes. To identify the similarities in seasonal patterns of soil respiration and in situ enzyme potentials, we compared the modelled in situ enzyme activities with weekly measured soil CO2 emissions. Arable soil samples from two different treatments (4 years fallow and currently vegetated plots; treatments represent range of carbon input into soil) were collected every month from April, 2012 to April, 2013, from two different study regions (Kraichgau and Swabian Alb) in Southwest Germany. The vegetation plots were under crop rotation in both study areas. We measured activities of three enzymes including ?-glucosidase, xylanase and phenoloxidase at five different temperatures. We also measured soil microbial biomass in form of microbial carbon (Cmic). Land-use and area had significant effects (P < 0.001) on the microbial biomass; fallow plots having less Cmic than vegetation plots. Potential activities of ?-glucosidase (P < 0.001) and xylanase (P < 0.01) were significantly higher in the vegetation plots of the Swabian Alb region than in the Kraichgau region. In both study areas, enzyme activities were higher during vegetation period and lower during winter which points to the importance of carbon input and/or temperature and soil moisture. We calculated the temperature sensitivity (Q10) of enzyme activities based on laboratory measurements of enzyme activities at a range of incubation temperatures. Q10 of ?-glucosidase activity changed significantly across the year (Q10 values ranges from 1.5 to 2.0 in Kraichgau and 1.6 to 2.1 in Swabian Alb), while for xylanase activity, no significant effects were found (Q10 values ranges from 1.2 to 3.0 in Kraichgau and 1.3 to 3.3 in Swabian Alb) in both study regions. By using laboratory based enzyme activities, calculated Q10 values, and daily soil temperature data, we modelled in situ enzyme potentials in soils for labile and recalcitrant carbon pools for both study regions. We observed an increase in modelled in situ enzyme activities during the summer period and a substantial decrease during winter indicating temperature as a strong controlling factor. A significant higher positive correlation of soil surface CO2 flux with modelled in situ ?-glucosidase activity was found in both study regions compared to modelled in situ xylanase activity. These results demonstrate that (1) Q10 values are site and season specific and should be added into carbon models and (2) the indication of the relevance of greater contribution of labile carbon pool to soil CO2 emissions.

  12. The Influence of vegetation on processes of shallow soil erosion in subalpine catchment areas in Western Austria

    NASA Astrophysics Data System (ADS)

    von der Thannen, M.; Weissteiner, C.; Rauch, H. P.; Tilch, N.; Kohl, B.

    2012-04-01

    Shallow soil erosion processes have been increasing within the last decades in the high montane and subalpine altitudinal zone of Western Austria. Explanations for the progression of eroded areas in the 2nd half of the 20th century have been subject of various research projects. The studies result in different possible explanations and process catenae regarding triggering effects, material dislocation processes and a following development of the erosive spots. Diverse results are based on different scales of the studies and the specific disciplinary driven approach of the researchers. In order to better understand the process catenae of the dynamics of shallow soil erosion processes this research project is based on an interdisciplinary, pluri-scale approach applied in different areas of the subalpine zone in Western Austria. The focus of this paper is restricted to one catchment area and highlights the influence of different plant parameters on shallow soil erosion processes. The research area "Thüringerberg" is located in the lithographic flysch unit in the subalpine zone in Vorarlberg, in Western Austria. Its vegetation is strongly characterized by agricultural activities of local people, mainly alpine pasturing. Generally the vegetation can be classified in three different types of vegetation: dry grasslands, pioneers and higher perennial herbs. The grassland, which is dominating in the area, is dominated by the vegetation community Caricetum ferrugineae. Additionally Seslerio-Semperviretum, Polygono-Trisetion, defective vegetation community with Agrostis stolonifera and defective vegetation community with Dactylis glomerata occur. Fieldwork has been conducted during summer 2011, from August, 8th up to the 18th, at highest development level of the plants. Vegetation data has been recorded around every single soil erosion process (above, sideways, below and inside). Observed vegetation parameters are: height, frequency, distribution, coverage and dominance. Results from vegetational statistical analysis in correlation with geomorphological and hydrological parameters have been used to identify significant soil erosion process characteristics. Furthermore the results can be used to forecast the future development of the current situation.

  13. Simulating the effects of soil organic nitrogen and grazing on arctic tundra vegetation dynamics on the Yamal Peninsula, Russia

    NASA Astrophysics Data System (ADS)

    Yu, Q.; Epstein, H. E.; Walker, D. A.

    2009-12-01

    Sustainability of tundra vegetation under changing climate on the Yamal Peninsula, northwestern Siberia, home to the world’s largest area of reindeer husbandry, is of crucial importance to the local native community. An integrated investigation is needed for better understanding of the effects of soils, climate change and grazing on tundra vegetation in the Yamal region. In this study we applied a nutrient-based plant community model (ArcVeg) to evaluate how two factors (soil organic nitrogen [SON] levels and grazing) interact to affect tundra responses to climate warming across a latitudinal climatic gradient on the Yamal Peninsula. Model simulations were driven by field-collected soil data and expected grazing patterns along the Yamal Arctic Transect (YAT), within bioclimate subzones C (High Arctic), D (northern Low Arctic) and E (southern Low Arctic). Plant biomass and NPP (net primary productivity) were significantly increased with warmer bioclimate subzones, greater soil nutrient levels and temporal climate warming, while they declined with higher grazing frequency. Temporal climate warming of 2 °C caused an increase of 665 g/m2 in total biomass at the high SON site in subzone E, while only 298 g/m2 in the low SON site. When grazing frequency was also increased, total biomass increased by only 369 g/m2 in the high SON site in contrast to 184 g/m2 in the low SON site in subzone E. When comparing low grazing to high grazing effects on soil organic nitrogen pools over time (Figure 1), higher grazing frequency led to either slower SON accumulation rates or more rapid SON depletion rates. Warming accentuated these differences caused by grazing, suggesting the interaction between grazing and warming may yield greater differences in SON levels across sites. Our results suggest that low SON and grazing may limit plant response to climate change. Interactions among bioclimate subzones, soils, grazing and warming significantly affect plant biomass and productivity in the arctic tundra and should not be ignored in regional scale studies.

  14. Prediction of soil properties using imaging spectroscopy: Considering fractional vegetation cover to improve accuracy

    NASA Astrophysics Data System (ADS)

    Franceschini, M. H. D.; Demattê, J. A. M.; da Silva Terra, F.; Vicente, L. E.; Bartholomeus, H.; de Souza Filho, C. R.

    2015-06-01

    Spectroscopic techniques have become attractive to assess soil properties because they are fast, require little labor and may reduce the amount of laboratory waste produced when compared to conventional methods. Imaging spectroscopy (IS) can have further advantages compared to laboratory or field proximal spectroscopic approaches such as providing spatially continuous information with a high density. However, the accuracy of IS derived predictions decreases when the spectral mixture of soil with other targets occurs. This paper evaluates the use of spectral data obtained by an airborne hyperspectral sensor (ProSpecTIR-VS - Aisa dual sensor) for prediction of physical and chemical properties of Brazilian highly weathered soils (i.e., Oxisols). A methodology to assess the soil spectral mixture is adapted and a progressive spectral dataset selection procedure, based on bare soil fractional cover, is proposed and tested. Satisfactory performances are obtained specially for the quantification of clay, sand and CEC using airborne sensor data (R2 of 0.77, 0.79 and 0.54; RPD of 2.14, 2.22 and 1.50, respectively), after spectral data selection is performed; although results obtained for laboratory data are more accurate (R2 of 0.92, 0.85 and 0.75; RPD of 3.52, 2.62 and 2.04, for clay, sand and CEC, respectively). Most importantly, predictions based on airborne-derived spectra for which the bare soil fractional cover is not taken into account show considerable lower accuracy, for example for clay, sand and CEC (RPD of 1.52, 1.64 and 1.16, respectively). Therefore, hyperspectral remotely sensed data can be used to predict topsoil properties of highly weathered soils, although spectral mixture of bare soil with vegetation must be considered in order to achieve an improved prediction accuracy.

  15. Land surface phenologies viewed in the middle infrared: seasonal contrasts between vegetation, soils, and impervious surfaces

    NASA Astrophysics Data System (ADS)

    Henebry, G. M.; Krehbiel, C.; Kovalskyy, V.

    2012-12-01

    The middle infrared (MIR) region of the electromagnetic spectrum spans 3-5 microns. It is the mixing zone between reflected sunlight and emitted earthlight in roughly equal proportions. This region has received very little attention in terrestrial remote sensing. Yet the MIR merits exploration of how it could be used for monitoring land surface phenologies (LSP) and seasonalities due to five characteristics. First, green vegetation is MIR-dark, reflecting just 2-5% of the incident radiation. Second, soils are MIR-bright, reflecting up to one-third of the incident radiation. Third, impervious surfaces, such as concretes, asphalts, and other building and paving materials are also MIR-bright. Fourth, the resulting seasonal contrast in MIR between vegetated and non-vegetated surfaces lets urbanized areas emerge from the vegetated landscape. Fifth, MIR wavelengths penetrate anthropogenic haze and smoke because the particle radii are smaller. Here we use MODIS (MYD02) image time series to illustrate the temporal progressions of MIR at various wavelengths and how they compare to and diverge from the more familiar NDVI and derived LSP metrics.IR portrait of the USA east of W98: maximum value composite of Aqua MODIS MIR band 23 during DOY 219-233 of 2010.

  16. ? 13C values of soil organic carbon and their use in documenting vegetation change in a subtropical savanna ecosystem

    Microsoft Academic Search

    Thomas W Boutton; Steven R Archer; Andrew J Midwood; Stephen F Zitzer; Roland Bol

    1998-01-01

    Plants with C3, C4, and CAM photosynthesis have unique ?13C values which are not altered significantly during decomposition and soil organic matter formation. Consequently, ?13C values of soil organic carbon reflect the relative contribution of plant species with C3, C4, and CAM photosynthetic pathways to community net primary productivity, and have been utilized to document vegetation change, to quantify soil

  17. Changes in soil and vegetation following stabilisation of dunes in the southeastern fringe of the Tengger Desert, China

    Microsoft Academic Search

    X. R. Li; D. S. Kong; H. J. Tan; X. P. Wang

    2007-01-01

    Properties of the soil and sand-binding vegetation were measured at five sites plus a control on dunes of the Tengger Desert\\u000a stabilized for periods of up to 50 years. In the topsoil, fine particles, total N, P, K and organic matter increased significantly\\u000a with increasing site age. However, there were no significant changes in deeper soil profiles (>0.4 m depth). Soil pH,

  18. Soil wetting patterns of vegetation and inter-patches following single and repeated wildfires

    NASA Astrophysics Data System (ADS)

    González, Óscar; Malvar, Maruxa; van den Elsen, Erik; Hosseini, mohammadreza; Coelho, Celeste; Ritsema, Coen; Bautista, Susana; Keizer, Jan Jacob; Cerdà, Artemi

    2015-04-01

    Although wildfires spread in Mediterranean areas are considered a natural processes, the expected increase in fire frequency has raised concerns about the systems' future resilience (Pausas, 2004). Besides more frequent, future wildfires can become more severe and produce more pronounced changes in topsoil properties, vegetation and litter (Cerdá and Mataix-Solera, 2009). To deal with challenges, the EU funded CASCADE and RECARE projects, which are currently assessing soil threats and tipping-points for land degradation in a climatic gradient across Europe. The present research was developed in Portugal and aims to find relationships between fire frequency and soil wetting patterns following single versus repeated wildfires. In September 2012, a wildfire burnt 3000 ha. of Pine stands and shrub vegetation in the vicinity of Viseu district, North-Central Portugal. Analyses according to the available burnt-area maps (1975-2012), discriminated areas that has been burned 1x (called SD) and 4x (called D) times. In order to evaluate the post-fire soil surface moisture patterns, 6 slopes (3 in SD and 3 in D) were selected and a balanced experimental design with 72 soil moisture sensors (EC5 and GS3, from Decagon devices) was implemented under shrubs (n=18) and on bare (n=18) soil environments, at 2.5 cm and 7.5 cm soil depth each. The spatio-temporal occurrence of soil water repellence (SWR) (Keizer et al., 2008; Prats et al., 2013; Santos et al., 2014) was monthly assessed through the MED test at 2.5 cm and 7.5 cm soil depth into 5 sampling points located at regular distances along a transect running from the top to bottom of a selected slope in SD and D. Automatic and totalize rainfall gauges were also installed across the study area. Preliminary results showed that soil wetting patterns and SWR occurrence differs between SD, D sites and, between soil environment (under shrubs and on bare soil areas). SWR were more pronounced on the SD than in D, affecting soil wetting cycles. Soil moisture content and antecedent rainfall were both correlated with SWR, although insufficient to predict the temporal variations. Antecedent and maximum soil moisture were close related with the SWR status and data analyses showed a top-down breaking mechanism on the SWR Acknowledgements. The research projects CASCADE FP7 (ENV.2011.2.1.4, www.cascade-project.eu) AND RECARE FP7 (n° 603498, http://recare-project.eu/) supported this research. References. Cerdá, A., Mataix-Solera, J., 2009. Incendios forestales en España. Ecosistemas terrestres y suelos. En: Efectos de los incendios forestales sobre los suelos en España. Cerda and Mataix-Solera (eds). Universidad de Valencia, Valencia (España). 529 pp. Keizer, J.J., Doerr, S.H., Malvar, M.C., Prats, S.A., Ferreira, R.S.V., Oñate, M.G., Coelho, C.O.A., Ferreira, A.J.D., 2008. Temporal variation in topsoil water repellency in two recently burnt eucalypt stands in north-central Portugal. Catena 74 (3), 192-204. Pausas, J., 2004. Changes in fire and climate in the eastern Iberian Peninsula (Mediterranean basin). Climatic Change, 63: 330-340. Prats, S.A., Malvar, M., Vieira, D.C.S., McDonald, L., Keizer, J.J. 2013. Effectiveness of hydromulching to reduce runoff and erosion in a recently burnt pine plantation in central Portugal. Land Degradation and Development. DOI: 10.1002/ldr.2236. Santos J.M., Verheijen F.G.A., Wahren F.T., Wahren A., Feger K.H., Bernard-Jannin L., Rial Rivas M.E., Keizer J.J., Nunes J.P. 2014. Soil Water Repellency dynamics in Pine and Eucalypt plantations in Portugal - A high resolution time series. Land Degradation & Development. DOI: 10.1002/ldr.2251.

  19. The response of Arctic vegetation and soils following an unusually severe tundra fire

    PubMed Central

    Bret-Harte, M. Syndonia; Mack, Michelle C.; Shaver, Gaius R.; Huebner, Diane C.; Johnston, Miriam; Mojica, Camilo A.; Pizano, Camila; Reiskind, Julia A.

    2013-01-01

    Fire causes dramatic short-term changes in vegetation and ecosystem function, and may promote rapid vegetation change by creating recruitment opportunities. Climate warming likely will increase the frequency of wildfire in the Arctic, where it is not common now. In 2007, the unusually severe Anaktuvuk River fire burned 1039 km2 of tundra on Alaska's North Slope. Four years later, we harvested plant biomass and soils across a gradient of burn severity, to assess recovery. In burned areas, above-ground net primary productivity of vascular plants equalled that in unburned areas, though total live biomass was less. Graminoid biomass had recovered to unburned levels, but shrubs had not. Virtually all vascular plant biomass had resprouted from surviving underground parts; no non-native species were seen. However, bryophytes were mostly disturbance-adapted species, and non-vascular biomass had recovered less than vascular plant biomass. Soil nitrogen availability did not differ between burned and unburned sites. Graminoids showed allocation changes consistent with nitrogen stress. These patterns are similar to those seen following other, smaller tundra fires. Soil nitrogen limitation and the persistence of resprouters will likely lead to recovery of mixed shrub–sedge tussock tundra, unless permafrost thaws, as climate warms, more extensively than has yet occurred. PMID:23836794

  20. Separating the contributions of vegetation and soil to evapotranspiration using stable isotopes

    NASA Astrophysics Data System (ADS)

    Cuntz, Matthias; Dubbert, Maren; Piayda, Arndt; Correia, Alexandra; Silva, Filipe Costa e.; Kolle, Olaf; Maguás, Cristina; Mosena, Alexander; Pereira, João S.; Rebmann, Corinna; Werner, Christiane

    2015-04-01

    Semi-arid ecosystems contribute about 40% to global net primary productivity, although water-availability limits carbon uptake. Precipitation shows periodical summer droughts and evapotranspiration accounts for up to 95% of water loss of the ecosystem. Thus functional understanding of evapotranspiration and the contributions of evaporation and transpiration from over- and understorey vegetation to water cycling in semi-arid regions is key knowledge in forest management under future climate change. Water isotopes trace water through the compartments of an ecosystem from soil and the vegetation to the atmosphere. They are used to partition evapotranspiration ET into its components evaporation E and transpiration T . The method is, however, sensitive to the knowledge of the isotopic composition of water at the evaporating sites. This led to a discussion recently about the dominance of transpiration in water loss from the terrestrial biosphere, and also how methodological problems could bias these results. Here we present observations from a Portuguese cork-oak woodland. It is a bi-layered system of widely spaced cork-oak trees and a herbaceous layer dominated by native annual forbs and grasses. Water fluxes and their isotopic compositions were measured on bare soil and vegetated plots with a transparent through-flow chamber and a water isotope laser. Soil moisture and temperature were measured in several depths and soil samples were taken for soil water isotope analysis. Based on these observations, we review current strategies of ET partitioning. We highlight pitfalls in the presented strategies and show uncertainty analyses for the different approaches. We show that the isotopic composition of evaporation is very sensitive to the sampling strategy but is described well by a steady-state formulation (Dubbert et al., J Hydrolo 2013). The isotopic composition of transpiration, on the other hand, is not in steady state, most of the time (Dubbert et al., New Phytolo 2014). We will demonstrate the consequences for the partitioning of ET of current simplifications in soil moisture isotope descriptions and current steady-state assumption for transpiration isotopes.

  1. Numerical modeling of diazinon transport through inter-row vegetative filter strips.

    PubMed

    Watanabe, Hirozumi; Grismer, Mark E

    2003-10-01

    A numerical simulation model of pesticide runoff through vegetative filer strips (PRVFS) was developed as a tool for investigating the effects of pesticide transport mechanisms on VFS design in dormant-sprayed orchard. The PRVFS model was developed applying existing theories such as kinematic wave theory and mixing zone theory for pesticide transport in the bare soil area. For VFS area, the model performs flow routing by simple mass accounting in sequential segments and the pesticide mass balance by considering pesticide washoff and adsorption processes on the leaf, vegetative litter, root zone and soil. Model sensitivity analysis indicated that pesticide transfer from surface soil to overland flow and pesticide washoff from the VFS were important mechanisms affecting diazinon transport. The VFS cover ratio and rainfall intensity can be important design parameters for controlling diazinon runoff using inter-row VFS in orchard. The PRVFS model was validated using micro-ecosystem simulation of diazinon transport for 0, 50 and 100% VFS cover conditions. The PRVFS model is shown to be a beneficial tool for evaluating and analyzing possible best management practices for controlling offsite runoff of dormant-sprayed diazinon in orchards during the rainy season. PMID:14550658

  2. Modelling daily soil respiration in lowland oak forest during and after soil water saturation events

    NASA Astrophysics Data System (ADS)

    Marjanovic, Hrvoje; Zorana Ostrogovic, Masa; Alberti, Giorgio; Peressotti, Alessandro

    2013-04-01

    Lowland forests of pedunculate oak (Quercus robur L.) in Croatia are acclimated to high soil water content and flooding during the cold part of the year (November - March). Changes in weather pattern and increasing frequency of extreme events, like high precipitation episodes or flooding events out of dormancy period, are becoming more likely. However, the response of these forest ecosystems to flooding during vegetation period is not well investigated. It is well known that soil respiration (SR) depends on soil water content. Nevertheless, some of the most popular daily time-step SR models, like the one of Reichstein et al (2003), do not take into account the effects of soil water saturation which leads to hypoxia in soil and decline of SR. Therefore, we propose a modification of the SR model of Reichstein et. al (2003) that takes into account the effects of high soil water content on SR. In a 37 years old forest of pedunculate oak, located in Jastrebarsko forest (N45.619, E15.688), we measured soil CO2 efflux, every four hours during years 2009 and 2010, using a closed dynamic system with 2-4 chambers. Measured effluxes were averaged to obtain a daily average CO2 efflux. Measurements have shown that high soil water content (i.e. greater that field capacity) strongly decreases soil CO2 efflux, while subsequent soil draining produces bursts in efflux, particularly in spring. Assuming that the measured CO2 efflux corresponds to the total SR, we parameterized the original Reichstein et al (2003) daily time-step SR model and models based on the original but with different modifications (added seasonality in LAI term, modification in soil water status term, addition of new pulse term due to soil draining) and their combinations. Performance of each model was assessed using standard statistical measures (R2, RMSE, Mean Absolute Error, Nash-Sutcliffe Efficiency). Modification of soil water status term significantly improved daily SR estimate (RMSE 0.67) compared to original model (RMSE 0.82), particularly during flooding and post-flooding periods. Annual SR estimated with new model showed greater variability than the estimates with the original model which could be plausible if differences in meteorological conditions between relatively dry 2009 and very wet 2010 are taken into account. New SR models could find application in wet ecosystems or during flooding events. However, additional validation with an independent dataset would be useful.

  3. Relating biomass and vegetation structure in water limited ecosystems using a celluar automata based model

    NASA Astrophysics Data System (ADS)

    Frechen, Nanu; Hinz, Christoph; McGrath, Gavan

    2015-04-01

    Within arid and semiarid regions banded vegetation patterns are wide spread. While the soil-vegetation feedback causing this self-organized has been well understood and implemented in various models, the relationship between the actual pattern, e.g. band width and spacing as well as plant density, has not been well understood. In this study we use a cellular automaton [1] to investigate the effect of infiltration properties and rainfall on patter formation as well as on biomass production and vegetation coverage. The first part of the investigation showed that the model is consistent with the existing knowledge on the dependence of wavelength on annual rainfall. We use the same parameter space to assess biomass and fractional coverage. We found that there is a nonlinear relationship between biomass and infiltration capacity normalized with rainfall input. This indicates that the degree of organisation is not directly related to the productivity as expressed with biomass. Similar results were found for fractional surface cover of the vegetation. [1] McGrath, G. S., K. Paik, and C. Hinz. 2012. Microtopography alters self-organized vegetation patterns in water-limited ecosystems, Journal of Geophysical Research: Biogeosciences (2005-2012) 117, G03021, doi:10.1029/2011JG001870

  4. Effect of vegetation on soil profile formation: results of a 47-years experiment

    NASA Astrophysics Data System (ADS)

    Gunina, Anna; Ryzhova, Irina; Kuzyakov, Yakov

    2013-04-01

    Typical soil formation period in boreal ecosystems takes over centuries or longer. However, the rates of individual processes vary and consequently soil horizons and properties have different development periods. To evaluate the effect of vegetation, as a single factor, on the development of organic horizons, we used the soils of the lysimeters at Moscow State University. We generalized own results and long-term observations published before. In 1965 the lysimeters (S=9 m2, depth=1.5 m) were filled with carbonate free clay loam taken in Moscow region and originated from the Valday glaciation. The initial pH was 5.7, and Corg 0.07%. The following plant communities were created in the lysimeters: 1) Picea abies, 2) Picea abies + Quercus robur + Acer platanoides, 3) Quercus robur + Acer platanoides, 4) grasses (10 species with domination of Lolium and Trifolium) and 5) agricultural crops (9-field rotation). After 20, 33 and 47 years the morphological description of soil profiles was done and Corg was measured in the upper horizons. Additionally, the combined density and aggregate fractionation (>2000 µm, 250-2000 µm and <250 µm) of soils sampled from the upper 0-5 cm under three vegetation types (1, 3, and 5) was done after 47 years. Only litter horizons were formed on forest plots after 20 years. The horizons had various thicknesses but similar structure: the litter horizons were 0-2 cm high under the coniferous and broadleaf forests and consisted of L and H layers. Under mixed forest however, it comprised 0-0.5 cm and consisted of moss litter permeated with fungi hyphens. Mineral part of profiles was slightly colored with organic matter, whereas under grassland the Ah horizon (0-5 cm) was developed. After 33 years under forest, the Ah horizons (0-5 cm) were already developed and had a lot of roots and organic residues. The rates of Corg accumulation were different with the values varying between 0.08 and 0.38% Corg year-1. After 47 years of soil formation, the Corg in 0-5 of Ah reached 5.3%, 2.93%, 8.2%, 2.1% and 0.9% for coniferous, mixed, deciduous, grassland and agricultural crops respectively. The depth distribution of Corg is sharply decreases in all soil profiles. The combined aggregate-density fractionation had shown, that 30-74% of Corg of aggregates were associated with heavy mineral fraction (?>2 g cm-3). In agricultural soil, this fraction was higher than in forest soils. High amount of non-hydrolized C (literature data) also reflected the strong connections of Corg with mineral matrix. The light fraction (?<1.6 g cm-3) comprised 15-40% of Corg in aggregates and was maximal in forest soils. This could reflect differences in chemical composition of plant residues and rates of their decomposition as well as differences in their annual amounts. We conclude that vegetation type has strong effect on organic matter formation and C accumulation at early stages of soil development.

  5. Climate Impacts of Potential Vegetation versus Current Day MODIS Land Cover in the Community Climate System Model (CCSM)

    Microsoft Academic Search

    P. J. Lawrence; T. N. Chase

    2007-01-01

    Numerous studies have used General Circulation Models to investigate the possible climate impacts that human development has had through transforming the world from natural ecosystems to one dominated by cultivation, grazing, pastures and urban landscapes. In recent climate sensitivity studies we have found that the global representation of vegetation and soils, as well as the surface hydrology in the Community

  6. A Proposed Extension to the Soil Moisture and Ocean Salinity Level 2 Algorithm for Mixed Forest and Moderate Vegetation Pixels

    NASA Technical Reports Server (NTRS)

    Panciera, Rocco; Walker, Jeffrey P.; Kalma, Jetse; Kim, Edward

    2011-01-01

    The Soil Moisture and Ocean Salinity (SMOS)mission, launched in November 2009, provides global maps of soil moisture and ocean salinity by measuring the L-band (1.4 GHz) emission of the Earth's surface with a spatial resolution of 40-50 km.Uncertainty in the retrieval of soilmoisture over large heterogeneous areas such as SMOS pixels is expected, due to the non-linearity of the relationship between soil moisture and the microwave emission. The current baseline soilmoisture retrieval algorithm adopted by SMOS and implemented in the SMOS Level 2 (SMOS L2) processor partially accounts for the sub-pixel heterogeneity of the land surface, by modelling the individual contributions of different pixel fractions to the overall pixel emission. This retrieval approach is tested in this study using airborne L-band data over an area the size of a SMOS pixel characterised by a mix Eucalypt forest and moderate vegetation types (grassland and crops),with the objective of assessing its ability to correct for the soil moisture retrieval error induced by the land surface heterogeneity. A preliminary analysis using a traditional uniform pixel retrieval approach shows that the sub-pixel heterogeneity of land cover type causes significant errors in soil moisture retrieval (7.7%v/v RMSE, 2%v/v bias) in pixels characterised by a significant amount of forest (40-60%). Although the retrieval approach adopted by SMOS partially reduces this error, it is affected by errors beyond the SMOS target accuracy, presenting in particular a strong dry bias when a fraction of the pixel is occupied by forest (4.1%v/v RMSE,-3.1%v/v bias). An extension to the SMOS approach is proposed that accounts for the heterogeneity of vegetation optical depth within the SMOS pixel. The proposed approach is shown to significantly reduce the error in retrieved soil moisture (2.8%v/v RMSE, -0.3%v/v bias) in pixels characterised by a critical amount of forest (40-60%), at the limited cost of only a crude estimate of the optical depth of the forested area (better than 35% uncertainty). This study makes use of an unprecedented data set of airborne L-band observations and ground supporting data from the National Airborne Field Experiment 2005 (NAFE'05), which allowed accurate characterisation of the land surface heterogeneity over an area equivalent in size to a SMOS pixel.

  7. Soil feedback does not explain mowing effects on vegetation structure in a semi-natural grassland

    NASA Astrophysics Data System (ADS)

    Ilmarinen, Katja; Mikola, Juha

    2009-11-01

    Due to its ability to create aboveground conditions that favour plant diversity, mowing is often used to preserve the high conservation value of semi-natural species-rich grasslands. However, mowing can also affect belowground conditions. By decreasing plant carbon supply to soil, mowing can suppress the activity of soil decomposers, diminish plant nutrient availability and thus create a feedback on plant growth. In this study, we first documented the effects of three-year mowing on plant community structure in a species-rich grassland. We found that mowing decreased the total areal cover of woody plants and increased the total cover of leguminous forbs. At the species level, mowing further increased the cover of two non-leguminous forbs, Prunella vulgaris and Sagina procumbens. Mowing did not affect the species number, diversity or evenness of the plant community. To study whether any of these effects could be explained by mowing-induced changes in the soil, and particularly by reduced nutrient availability, we then collected soil from different treatment plots and monitored the growth of nine plant species in these soils in a greenhouse. Plant growth did not differ between soils collected from mowed and unmowed plots, suggesting that our mowing regimes did not impose such changes in soil decomposer activity and nutrient supply that would feedback on plant growth. Moreover, each of the nine species responded equally to the different nutrient availability in different parts of the grassland, which indicates that even if mowing had reduced plant nutrient supply, this would not have led to changes in plant community structure. It appears that those changes in aboveground vegetation that we recorded after three years of mowing were purely due to the aboveground effects, such as frequent cutting of woody plants and enhanced light availability for low-growing forbs.

  8. A Vegetation Correction Methodology for Time Series Based Soil Moisture Retrieval From C-band Radar Observations

    NASA Technical Reports Server (NTRS)

    Joseph, Alicia T.; O'Neil, P. E.; vanderVelde, R.; Gish, T.

    2008-01-01

    A methodology is presented to correct backscatter (sigma(sup 0)) observations for the effect of vegetation. The proposed methodology is based on the concept that the ratio of the surface scattering over the total amount of scattering (sigma(sup 0)(sub soil)/sigma(sup 0)) is only affected by the vegetation and can be described as a function of the vegetation water content. Backscatter observations sigma(sup 0) from the soil are not influenced by vegetation. Under bare soil conditions (sigma(sup 0)(sub soil)/sigma(sup 0)) equals 1. Under low to moderate biomass and soil moisture conditions, vegetation affects the observed sigma(sup 0) through absorption of the surface scattering and contribution of direct scattering by the vegetation itself. Therefore, the contribution of the surface scattering is smaller than the observed total amount of scattering and decreases as the biomass increases. For dense canopies scattering interactions between the soil surface and vegetation elements (e.g. leaves and stems) also become significant. Because these higher order scattering mechanisms are influenced by the soil surface, an increase in (sigma(sup 0)(sub soil)/sigma(sup 0)) may be observed as the biomass increases under densely vegetated conditions. This methodology is applied within the framework of time series based approach for the retrieval of soil moisture. The data set used for this investigation has been collected during a campaign conducted at USDA's Optimizing Production Inputs for Economic and Environmental Enhancement OPE-3) experimental site in Beltsville, Maryland (USA). This campaign took place during the corn growth cycle from May 10th to 0ctober 2nd, 2002. In this period the corn crops reached a vegetation water content of 5.1 kg m(exp -2) at peak biomass and a soil moisture range varying between 0.00 to 0.26 cubic cm/cubic cm. One of the deployed microwave instruments operated was a multi-frequency (C-band (4.75 GHz) and L-band (1.6 GHz)) quad-polarized (HH, HV, VV, VH) radar which was mounted on a 20 meter long boom. In the OPE-3 field campaign, radar observations were collected once a week at nominal times of 8 am, 10 am, 12 noon and 2 pm. During each data run the radar acquired sixty independent measurements within an azimuth of 120 degrees from a boom height of 12.2 m and at three different incidence angles (15,35, and 55 degrees). The sixty observations were averaged to provide one backscatter value for the study area and its accuracy is estimated to be 51.0 dB. For this investigation the C-band observations have been used. Application of the proposed methodology to the selected data set showed a well-defined relationship between (sigma(sup 0)(sub soil)/sigma(sup 0)) and the vegetation water content. It is found that this relationship can be described with two experimentally determined parameters, which depend on the sensing configuration (e.g. incidence angle and polarization). Through application of the proposed vegetation correction methodology and the obtained parameterizations, the soil moisture retrieval accuracy within the framework of a time series based approach is improved from 0.033 to 0.032 cubic cm/cubic cm, from 0.049 to 0.033 cubic cm/cubic cm and from 0.079 to 0.047 cubic cm/cubic cm for incidence angles of 15,35 and 55 degrees, respectively. Improvement in soil moisture retrieval due to vegetation correction is greater at larger incidence angles (due to the increased path length and larger vegetation effects on the surface signal at the larger angles).

  9. Dual-low frequency radar for soil moisture under vegetation at at-depth

    NASA Technical Reports Server (NTRS)

    Moghaddam, M.; Rodriguez, E.; Rahmat-Samii, Y.; Moller, D.

    2002-01-01

    To address a key science research topic for the global water and energy cycle, namely measuring soil moisture under substantial vegetation canopies and to useful depths, we have developed a concept for a synthetic aperture radar (SAR) system operating simultaneously at UHF and VHF frequencies. We are currently prototyping key technology items that enable this concept under the NASA Earth Science Technology Office (ESTO) Instrument Incubator Program (IIP). This presentation describes the technological challenges and innovations we are addressing to enable the implementation of this instrument and its integration into a future Earth-orbiting mission.

  10. Transpiration as the Leak in a Carbon Factory: A Model of Self-Optimising Vegetation

    NASA Astrophysics Data System (ADS)

    Sivapalan, M.; Schymanski, S. J.; Roderick, M. L.

    2005-12-01

    "Only now it occurred to me that plants are not water pumps but carbon factories" (Anonymous Hydrologist). When thinking of plants as `water pumps', we are led to the conclusion that vegetation would tend to maximise the total amount of transpiration while minimising the occurrence probability of periods without adequate water availability (`stress'). However, this does not do adequate justice to the fact that plants owe their existence to photosynthesis, and can thrive perfectly well even when the relative humidity of the air is very high and transpiration is almost negligible. In this paper, we present a model in which the maximisation of net CO2 uptake rather than maximisation of water use or minimisation of `stress' is assumed to be the driving force behind natural selection. Transpiration is the inevitable consequence of CO2 uptake from the atmosphere and water uptake from the soil incurs construction and maintenance costs of a root system, so that water use strategies become a consequence of the maximisation of net CO2 uptake and `stress' becomes an obsolete feature. We will demonstrate that a simple model based on ecological optimality is capable of reproducing some vegetation and water balance dynamics without any prior knowledge about the vegetation on a particular site. The model is based on a physical water balance model by Reggiani et al. (2000), an ecophysiological gas exchange and photosynthesis model (Cowan and Farquhar 1977; von Caemmerer 2000), and the hypothesis that natural selection leads to a vegetation type that optimally uses available resources to maximise its `net carbon profit' (the net tradeoff between carbon acquired by photosynthesis and carbon spent on maintenance of the organs involved in its uptake). While, at this early stage of its development, the site properties such as soil type and depth, topography and climate still have to be prescribed, the model creates the `optimal' dynamically adjusting vegetation for the particular site and calculates the water- and CO2- fluxes between soil, watershed boundaries, vegetation and atmosphere. Cowan, I. R. and G. D. Farquhar (1977). Stomatal Function in Relation to Leaf Metabolism and Environment. Integration of activity in the higher plant. D. H. Jennings. Cambridge, Cambridge University Press: 471-505. Reggiani, P., M. Sivapalan, et al. (2000). Conservation equations governing hillslope responses: Exploring the physical basis of water balance. Water Resources Research 36(7): 1845-1863. von Caemmerer, S. (2000). Biochemical Models of Leaf Photosynthesis. Collingwood, CSIRO Publishing.

  11. Human health risk assessment of heavy metals in soil-vegetable system: a multi-medium analysis.

    PubMed

    Liu, Xingmei; Song, Qiujin; Tang, Yu; Li, Wanlu; Xu, Jianming; Wu, Jianjun; Wang, Fan; Brookes, Philip Charles

    2013-10-01

    Vegetable fields near villages in China are suffering increasing heavy metal damages from various pollution sources including agriculture, traffic, mining and Chinese typical local private family-sized industry. 268 vegetable samples which included rape, celery, cabbages, carrots, asparagus lettuces, cowpeas, tomatoes and cayenne pepper and their corresponding soils in three economically developed areas of Zhejiang Province, China were collected, and the concentrations of five heavy metals (Pb, Cd, Cr, Hg and As) in all the samples were determined. The health risk assessment methods developed by the United States Environmental Protection Agency (US EPA) were employed to explore the potential health hazards of heavy metals in soils growing vegetables. Results showed that heavy metal contaminations in investigated vegetables and corresponding soils were significant. Pollution levels varied with metals and vegetable types. The highest mean soil concentrations of heavy metals were 70.36 mg kg(-1) Pb, 47.49 mg kg(-1) Cr, 13.51 mg kg(-1) As, 0.73 mg kg(-1) for Cd and 0.67 mg kg(-1) Hg, respectively, while the metal concentrations in vegetables and corresponding soils were poorly correlated. The health risk assessment results indicated that diet dominated the exposure pathways, so heavy metals in soil samples might cause potential harm through food-chain transfer. The total non-cancer and cancer risk results indicated that the investigated arable fields near industrial and waste mining sites were unsuitable for growing leaf and root vegetables in view of the risk of elevated intakes of heavy metals adversely affecting food safety for local residents. Chromium and Pb were the primary heavy metals posing non-cancer risks while Cd caused the greatest cancer risk. It was concluded that more effective controls should be focused on Cd and Cr to reduce pollution in this study area. PMID:23831799

  12. Markov models and initial floristic composition in heathland vegetation dynamics

    Microsoft Academic Search

    R. J. Hobbs; C. J. Legg

    1984-01-01

    A simple Markov model is used to test the hypothesis that the floristic composition of vegetation colonizing bare ground immediately after burning is the major factor influencing post-fire development in heathland vegetation. Data are taken from stands of different ages at time of burning in a species-rich Calluna-Arctostaphylos heath in NE Scotland. It is shown that variation in the initial

  13. Contamination of soil, leaves and vegetables by polychlorinated biphenyls in Xiamen region, China.

    PubMed

    Maskaoui, Khalid; Zhou, Jun-Liang; Han, Ya-Li; Hu, Zhong; Zheng, Tian-Ling; Hong, Hua-Sheng

    2005-01-01

    The paper aimed to identify the primary of polychlorinated biphenyls(PCBs) in the Jiulong River Estuary, investigate the spatial distribution of PCBs contamination in the environment, localize the atmospheric source and evaluate ongoing PCBs emissions by analyzing soil samples collected along the Jiulong River region. In addition, the accumulation of PCBs in the human food chain was quantified by analyzing leaf of orange trees and vegetable samples collected along a gradient of soil/atmospheric contamination moving away from the source. Consequently, the impact on the human health and the ecosystem was quantified, different management options were proposed to reduce this impact and to carry out research on organic contaminants along the Jiulong River and Xiamen region. PMID:16083125

  14. Modeling the interaction between flow and highly flexible aquatic vegetation

    NASA Astrophysics Data System (ADS)

    Dijkstra, J. T.; Uittenbogaard, R. E.

    2010-12-01

    Aquatic vegetation has an important role in estuaries and rivers by acting as bed stabilizer, filter, food source, and nursing area. However, macrophyte populations worldwide are under high anthropogenic pressure. Protection and restoration efforts will benefit from more insight into the interaction between vegetation, currents, waves, and sediment transport. Most aquatic plants are very flexible, implying that their shape and hence their drag and turbulence production depend on the flow conditions. We have developed a numerical simulation model that describes this dynamic interaction between very flexible vegetation and a time-varying flow, using the sea grass Zostera marina as an example. The model consists of two parts: an existing 1DV k-? turbulence model simulating the flow combined with a new model simulating the bending of the plants, based on a force balance that takes account of both vegetation position and buoyancy. We validated this model using observations of positions of flexible plastic strips and of the forces they are subjected to, as well as hydrodynamic measurements. The model predicts important properties like the forces on plants, flow velocity profiles, and turbulence characteristics well. Although the validation data are limited, the results are sufficiently encouraging to consider our model to be of generic value in studying flow processes in fields of flexible vegetation.

  15. Effect of vegetation physiology and structure on thermal and hydrological state in a coupled terrestrial system model

    NASA Astrophysics Data System (ADS)

    Lu, Yen-Sen; Rihani, Jehan; Langensiepen, Matthias; Simmer, Clemens

    2015-04-01

    When simulating the circulation of energy and moisture in the terrestrial system, vegetation is one of the key factors which affect energy and water fluxes at land surface and in the subsurface. Vegetation physiology in the terrestrial system includes transpiration, respiration, and root water uptake. One of the main vegetation schemes controlling transpiration in Land Surface Models is the empirical parameterization for stomatal conductance. There are two main types of stomatal conductance used in land surface models: the Jarvis-Stewart type based on environmental factors such as light use efficiency, temperature, vapor pressure deficit, and soil moisture limit: and the Ball-Berry type based on photosynthesis schemes with a semi-mechanistic parameterization. Moreover, the interconnection between soil moisture and stomatal conductance is not fully understood and needs further investigation. Alongside stomatal conductance, Leaf area index (LAI) also has a significant effect on the modelling system and thereby can impact the calculation of latent heat and sensible heat fluxes, ground temperature, and soil moisture. LAI represents the vegetation structure effects on the hydrological and thermal state of land surface by interception, albedo, and shading, and therefore altering transpiration and leaf surface evaporation. LAI can be obtained from observations such as field and satellite measurement; or estimated using parameterization in Land Surface Models and Dynamic Vegetation Models.. This study focuses on how different vegetation schemes of stomatal conductance and LAI input effect land surface energy fluxes and groundwater flow, and how the uncertainty of different schemes propagates to the calculation of thermal and hydrologic state of land surface and soil moisture. To reach the research aims of this study, land surface simulations and coupled land surface-groundwater simulations are performed and compared. In this numerical experiment, the modelling platform TerrSysMP is used. TerrSysMP consists of the regional circulation model COSMO, the land surface model Community Land Model 3.5 and the groundwater model ParFlow. An external coupler OASIS is used to run TerrSysMP in multiple coupling mode. ParFlow-CLM and standalone CLM are applied in this study in order to understand the interaction between vegetation and energy fluxes and water fluxes. Several different vegetation schemes of stomatal conductance such as Ball-Berry, Ball-Berry-Leuning, and Jarvis-Stewart types, as well as different LAI inputs such as MODIS LAI and a temperature-based LAI scheme are implemented and compared in this research. Sensitivity analysis is carried out to interpret how different vegetation schemes can affect energy and hydrologic fluxes in a real catchment.

  16. [Estimation model for daily transpiration of greenhouse muskmelon in its vegetative growth period].

    PubMed

    Zhang, Da-Long; Li, Jian-Ming; Wu, Pu-Te; Li, Wei-Li; Zhao, Zhi-Hua; Xu, Fei; Li, Jun

    2013-07-01

    For developing an estimation method of muskmelon transpiration in greenhouse, an estimation model for the daily transpiration of greenhouse muskmelon in its vegetative growth period was established, based on the greenhouse environmental parameters, muskmelon growth and development parameters, and soil moisture parameters. According to the specific environment in greenhouse, the item of aerodynamics in Penman-Monteith equation was modified, and the greenhouse environmental sub-model suitable for calculating the reference crop evapotranspiration in greenhouse was deduced. The crop factor sub-model was established with the leaf area index as independent variable, and the form of the model was linear function. The soil moisture sub-model was established with the soil relative effective moisture content as independent variable, and the form of the model was logarithmic function. With interval sowing, the model parameters were estimated and analyzed, according to the measurement data of different sowing dates in a year. The prediction accuracy of the model for sufficient irrigation and water-saving irrigation was verified, according to measurement data when the relative soil moisture content was 80%, 70%, and 60%, and the mean relative error was 11.5%, 16.2% , and 16.9% respectively. The model was a beneficial exploration for the application of Penman-Monteith equation under greenhouse environment and water-saving irrigation, having good application foreground and popularization value. PMID:24175525

  17. The influence of vegetation covers on soil moisture dynamics at high temporal resolution in scattered tree woodlands of Mediterranean climate

    NASA Astrophysics Data System (ADS)

    Lozano-Parra, Javier; Schnabel, Susanne; Ceballos-Barbancho, Antonio

    2015-04-01

    Soil water is a key factor that controls the organization and functioning of dryland ecosystems. However, in spite of its great importance in ecohydrological processes, most of the studies focus on daily or longer timescales, while its dynamics at shorter timescales are very little known. The main objective of this work was to determine the role of vegetation covers (grassland and tree canopy) in the soil hydrological response using measurements with high temporal resolution in evergreen oak woodland with Mediterranean climate. For this, soil water content was monitored continuously with a temporal resolution of 30 minutes and by means of capacitance sensors, mainly for the hydrological years 2010-2011 and 2011-2012. They were installed at 5, 10 and 15 cm, and 5 cm above the bedrock and depending on soil profile. This distribution along the soil profile is justified because soils are generally very shallow and most of the roots are concentrated in the upper layer. The sensors were gathered in 8 soil moisture stations in two contrasting situations characterized by different vegetation covers: under tree canopy and in open spaces or grasslands. Soil moisture variations were calculated at rainfall event scale at top soil layer and deepest depth by the difference between the final and initial soil moisture registered by a sensor at the finish and the beginning of the rainfall event, respectively. Besides, as soil moisture changes are strongly influenced by antecedent conditions, different antecedent soil moisture conditions or states, from driest to wettest, were also defined. The works were carried out in 3 experimental farms of the Spanish region of Extremadura. Results obtained revealed that rainwater amount bypassing vegetation covers and reaching the soil may temporarily be modified by covers according to precipitation properties and antecedent environmental conditions (from dry to wet) before the rain episode. Rainfall amounts triggering a positive soil hydrological response decreased as initial states became drier, being more accentuated below tree canopies. The frequency of the antecedent states seem to be as important or even more than duration or precipitation amount. The role of vegetation was more decisive under drier environmental conditions, where events lower than 6 mm and 2 mm never caused soil hydrological response either below tree canopy or grassland, respectively. This is important because initial conditions were independent of seasonality and because more than half of all rainfall events registered amounts smaller than 5 mm. If changes on temperature regime or precipitation patterns turn out in drier conditions, dry spells as well as the evaporative demand could increase, causing an increase of interception capacity of vegetation and consequently affecting ecological processes.

  18. Soil Moisture Experiments 2005 (SMEX05): Passive Microwave Polarimetric Signature Of Soil Moisture and Vegetation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Microwave remote sensing provides a direct measurement of soil moisture; however, there have been many challenges in algorithm science and technology that we have faced on the path to providing global measurements. Field experiments, especially those involving both ground and aircraft measurements, ...

  19. Effect of vegetation on infiltration into sandy soils during wet and dry spells

    NASA Astrophysics Data System (ADS)

    Orfanus, T.; Fodor, N.; Hallett, P. D.; Lichner, L.; Dlapa, P.; Rajkai, K.

    2012-04-01

    Plant cover can influence the hydraulic characteristics of soil considerably. Water repellency, which commonly evolves in sandy soils during longer dry spells, can result in water infiltration retardation. Water infiltration into natural-meadow, pine-forest, glade and fallow sandy soils was evaluated after during several wet and dry spells in respect of: soil porosity, hydraulic conductivity and sorptivity estimated by mini-disc infiltrometer, water drop penetration time, effective contact angle and water repellency index. Bare aeolian sand containing practically no organic matter was taken as etalon material. All materials have similar texture and pore-size distributions but their wettability and hydraulic properties differed considerably. Long dry spells enhanced the infiltration capacity in wettable etalon material because of sorptivity increase. Sorptivities of meadow and fallow soils, however, remained restrained during both, wet and dry seasons either due to higher water content (when wet) or to stronger water repellency (when dry). For this reason no temporal variability of infiltration capacity was observed in these soils unlike the etalon material. It was confirmed (for the fallow soil) that subcritical water repellency can significantly retarded water infiltration. The infiltration rate vs. time relationships measured both in the laboratory and field for the grass site revealed different behaviour in the initial phase of infiltration. In the laboratory, the onset of infiltration depended on the water ponding depth. As is often found in water repellent soil, the infiltration rate increased with time as a result of fingered flow. In the field, infiltration started immediately after the water application. This was the result of temporarily stable wetting patterns observed in all studied water repellent soils. Important founding is also that substantial part (71%) of the hydraulic conductivity variation in meadow soil could be explained by the variation of mean WDPT observed around the installed infiltrometer. The same was observed also for some other types of vegetation examined (pine forest, mosses and lichens on glade). However, no correlation existed between hydraulic conductivity and water repellency index possibly due to macropore flow dominating over the saturated hydraulic conductivity measurements.

  20. Does the composition of dissolved organic carbon (DOC) in peatland streams reflect the DOC leached from vegetation, litter and soil?

    NASA Astrophysics Data System (ADS)

    Chapman, Pippa; Holden, Joseph; Palmer, Sheila; Parry, Lauren; Wallage, Zoe; Wynne, Hannah

    2014-05-01

    Leaching of water-soluble compounds from fresh, senescent, and degraded plant biomass in contact with drainage water is an important process by which carbon, and other nutrients, are transferred from vegetation to soil and subsequently surface waters. Recent studies have shown that the quantity and quality of DOC leached from vegetation varies significantly with plant species. In blanket peatlands the dominant vegetation can vary from ericoid shrubs to sedges to acid grassland over quite short distances (meters). This variation in vegetation composition may be important in controlling the spatial variation observed in stream water DOC concentration and composition and therefore warrants further investigation, particularly in light of predicted changes in vegetation composition in response to climate change and/or changes in land management. This study (i) compared the amount and composition, in terms of its hydrophobicity, of DOC leached from a variety of plant and soil substrates from a blanket peatland in a laboratory experiment, and (ii) determined whether leachate DOC chemistry was reflected in the concentration and composition of DOC in soil waters, from patches of different vegetation types on the hillslope, and stream water from headwater catchments (< 40 ha). There were significant differences in the amount and quality of DOC released from three major plant functional types (PFT) found in blanket peatlands. Leachates from Calluna and Eriophorum contained more DOC than those from Sphagnum, whereas the composition of the DOC was dependent on vegetation state (living foliage or litter) rather than PFT. Leachates from living vegetation contained the lowest proportion of hydrophobic (HPO) compounds (average = 30%) and leachates from the peat the highest proportion of HPO (average = 62%), with leachates from litter containing on average 49% HPO. Although the amount of DOC in soil pore water reflected the results obtained from the leachate experiment, with larger concentrations observed in pore water beneath Eriophorum and Calluna compared to Sphagnum, the composition of DOC was similar beneath all vegetation types. As reported in other studies, stream water DOC composition, at baseflow, was dominated by the HPO fraction (average = 67%), which is more similar to that observed in leachates from the peat than leachates of living foliage and litter. The results show that while the quantity and quality of DOC leached from vegetation varied significantly with plant species, this was not reflected in soil water collected from beneath patches of different vegetation and streams draining catchments dominated by different vegetation. This suggests that microbial processes occurring within the peatland may be more important than the original source in determining the composition, in terms of hydrophobicity, of aquatic DOC.

  1. Terminal Restriction Fragment Length Polymorphism Analysis of Soil Bacterial Communities under Different Vegetation Types in Subtropical Area

    PubMed Central

    Wu, Zeyan; Lin, Wenxiong; Li, Bailian; Wu, Linkun; Fang, Changxun; Zhang, Zhixing

    2015-01-01

    Soil microbes are active players in energy flow and material exchange of the forest ecosystems, but the research on the relationship between the microbial diversity and the vegetation types is less conducted, especially in the subtropical area of China. In this present study, the rhizosphere soils of evergreen broad-leaf forest (EBF), coniferous forest (CF), subalpine dwarf forest (SDF) and alpine meadow (AM) were chosen as test sites. Terminal-restriction fragment length polymorphisms (T-RFLP) analysis was used to detect the composition and diversity of soil bacterial communities under different vegetation types in the National Natural Reserve of Wuyi Mountains. Our results revealed distinct differences in soil microbial composition under different vegetation types. Total 73 microbes were identified in soil samples of the four vegetation types, and 56, 49, 46 and 36 clones were obtained from the soils of EBF, CF, SDF and AM, respectively, and subsequently sequenced. The Actinobacteria, Fusobacterium, Bacteroidetes and Proteobacteria were the most predominant in all soil samples. The order of Shannon-Wiener index (H) of all soil samples was in the order of EBF>CF>SDF>AM, whereas bacterial species richness as estimated by four restriction enzymes indicated no significant difference. Principal component analysis (PCA) revealed that the soil bacterial communities’ structures of EBF, CF, SDF and AM were clearly separated along the first and second principal components, which explained 62.17% and 31.58% of the total variance, respectively. The soil physical-chemical properties such as total organic carbon (TOC), total nitrogen (TN), total phosphorus (TP) and total potassium (TK) were positively correlated with the diversity of bacterial communities. PMID:26098851

  2. Adsorption and desorption of atrazine, desethylatrazine, deisopropylatrazine, and hydroxyatrazine in vegetated filter strip and cultivated soil.

    PubMed

    Krutz, Larry Jason; Senseman, Scott Allen; McInnes, Kevin Joseph; Zuberer, David Allen; Tierney, Dennis Patrick

    2003-12-01

    Adsorption and desorption of atrazine and its metabolites in vegetated filter strip soil (VFS) has not been evaluated, yet these data are needed to predict the transport of these compounds through the VFS. Adsorption and desorption parameters for atrazine, desethylatrazine (DEA), deisopropylatrazine (DIA), and hydroxyatrazine (HA) were compared between a cultivated Houston Black clay (CS) and an adjacent 12-year-old VFS established in a mixed stand of bermudagrass [Cynodon dactylon (L.) Pers.] and buffalograss [Buchloe dactyloides (Nutt. Engelm)]. Adsorption and desorption isotherms were determined by batch equilibrium. The evaluated chemical and physical properties of the VFS and CS were similar with the exception of a 1.7-fold increase in the organic carbon content of the VFS. Adsorption and desorption coefficients for atrazine were at least 59% higher in VFS than in CS. The adsorption coefficient for HA was 48% higher in VFS compared with CS, but desorption was not statistically different between soils. Adsorption and desorption coefficients for DEA and DIA were not statistically different between soils. The predicted order of mobility in CS is HA < atrazine = DIA = DEA. In VFS, the predicted order of mobility is HA < atrazine = DIA < DEA. These data indicate that the higher organic carbon in VFS will likely retard the transport of atrazine and HA to surface and ground waters; however, the transport rates of DEA and DIA will be similar between soils. PMID:14640587

  3. Soil Moisture Estimate under Forest using a Semi-empirical Model at P-Band

    NASA Astrophysics Data System (ADS)

    Truong-Loi, M.; Saatchi, S.; Jaruwatanadilok, S.

    2013-12-01

    In this paper we show the potential of a semi-empirical algorithm to retrieve soil moisture under forests using P-band polarimetric SAR data. In past decades, several remote sensing techniques have been developed to estimate the surface soil moisture. In most studies associated with radar sensing of soil moisture, the proposed algorithms are focused on bare or sparsely vegetated surfaces where the effect of vegetation can be ignored. At long wavelengths such as L-band, empirical or physical models such as the Small Perturbation Model (SPM) provide reasonable estimates of surface soil moisture at depths of 0-5cm. However for densely covered vegetated surfaces such as forests, the problem becomes more challenging because the vegetation canopy is a complex scattering environment. For this reason there have been only few studies focusing on retrieving soil moisture under vegetation canopy in the literature. Moghaddam et al. developed an algorithm to estimate soil moisture under a boreal forest using L- and P-band SAR data. For their studied area, double-bounce between trunks and ground appear to be the most important scattering mechanism. Thereby, they implemented parametric models of radar backscatter for double-bounce using simulations of a numerical forest scattering model. Hajnsek et al. showed the potential of estimating the soil moisture under agricultural vegetation using L-band polarimetric SAR data and using polarimetric-decomposition techniques to remove the vegetation layer. Here we use an approach based on physical formulation of dominant scattering mechanisms and three parameters that integrates the vegetation and soil effects at long wavelengths. The algorithm is a simplification of a 3-D coherent model of forest canopy based on the Distorted Born Approximation (DBA). The simplified model has three equations and three unknowns, preserving the three dominant scattering mechanisms of volume, double-bounce and surface for three polarized backscattering coefficients: ?HH, ?VV and ?HV. The inversion process, which is not an ill-posed problem, uses the non-linear optimization method of Levenberg-Marquardt and estimates the three model parameters: vegetation aboveground biomass, average soil moisture and surface roughness. The model analytical formulation will be first recalled and sensitivity analyses will be shown. Then some results obtained with real SAR data will be presented and compared to ground estimates.

  4. Influences of calcium availability and tree species on Ca isotope fractionation in soil and vegetation

    USGS Publications Warehouse

    Page, B.D.; Bullen, T.D.; Mitchell, M.J.

    2008-01-01

    The calcium (Ca) isotope system is potentially of great use for understanding biogeochemical processes at multiple scales in forest ecosystems, yet remains largely unexplored for this purpose. In order to further our understanding of Ca behavior in forests, we examined two nearly adjacent hardwood-dominated catchments with differing soil Ca concentrations, developed from crystalline bedrock, to determine the variability of 44Ca/ 40Ca ratios (expressed as ??44Ca) within soil and vegetation pools. For both sugar maple and American beech, the Ca isotope compositions of the measured roots and calculated bulk trees were considerably lighter than those of soil pools at these sites, suggesting that the trees were able to preferentially take up light Ca at the root-soil interface. The Ca isotope compositions of three of four root samples were among the lightest values yet reported for terrestrial materials (??44Ca ???-3.95???). Our results further indicate that Ca isotopes were fractionated along the transpiration streams of both tree species with roots having the least ??44Ca values and leaf litter the greatest. An approximately 2??? difference in ??44Ca values between roots and leaf litter of both tree species suggests a persistent fractionation mechanism along the transpiration stream, likely related to Ca binding in wood tissue coupled with internal ion exchange. Finally, our data indicate that differing tree species demand for Ca and soil Ca concentrations together may influence Ca isotope distribution within the trees. Inter-catchment differences in Ca isotope distributions in soils and trees were minor, indicating that the results of our study may have broad transferability to studies of forest ecosystems in catchments developed on crystalline substrates elsewhere. ?? 2008 Springer Science+Business Media B.V.

  5. Measurement of Radionuclides and Gamma-Ray Dose Rate in Soil and Transfer of Radionuclides from Soil to Vegetation, Vegetable of Some Northern Area of Pakistan Using ?-Ray Spectrometry

    Microsoft Academic Search

    Hasan M. Khan; M. Ismail; Khalid Khan; Perveen Akhter

    2011-01-01

    The analysis of gamma emitters natural radionuclides, i.e., 226Ra, 232Th, and 40K, has been carried out in soil, vegetation, vegetable, and water samples collected from some Northern area of Pakistan, using\\u000a gamma-ray spectrometry. The ?-ray spectrometry was carried out using high-purity Germanium detector coupled with a computer-based\\u000a high-resolution multi-channel analyzer. The activity concentrations in soil ranges from 24.7 to 78.5 Bq?kg?1,

  6. 7 Phosphorus Modeling in Soil and Water

    E-print Network

    163 7 Phosphorus Modeling in Soil and Water Assessment Tool (SWAT) Model Indrajeet Chaubey...........................................................................164 7.2 Phosphorus Modeling in SWAT: Soil Phosphorus Interactions..................167 7.2.1 Initialization of Soil Phosphorus Levels......................................... 168 7.2.2 Mineralization

  7. Quantifying the Resilience of Vegetation and Soil Moisture During Dry Spells Using Satellite Remote Sensing

    NASA Astrophysics Data System (ADS)

    Stampoulis, D.; Andreadis, K.; Granger, S. L.; Fisher, J. B.; Behrangi, A.; Das, N. N.; Turk, J.

    2014-12-01

    Manifestations of the constantly intensifying hydrological cycle differ substantially among the various regions of the globe. The spatial distribution, magnitude, as well as timing of precipitation events are being altered globally, resulting in significant biotic implications. Motivated by the pressing need to understand how the different components of natural habitats behave under extreme hydrologic conditions, we quantitatively assessed the response of two major hydrological attributes, namely soil moisture (SM) and vegetation water content (VWC) to rainfall deficiencies. More specifically, using multi-year microwave remote sensing observations, we quantified the changes of VWC and SM during dry spells, as well as their resilience during those periods. Differences among vegetation types, as well as the effect of the duration of the dry spells were also investigated. Finally, spatial patterns and characteristics of the response of VWC and SM to sustained precipitation deficits were identified across the study area, and within each of the major vegetation regimes of the region. This hydro-ecological study provides critical insight into the behavior of two crucial components of the natural ecosystems during prolonged dry periods, which in turn yields useful information on the role of the hydrologic regimes in determining biotic composition and patterns, as well as the regional micro-climatology. Furthermore, this information can significantly contribute towards the achievement of more efficient and precise farming practices at the local level, resulting in the increase of food security and societal well-being.

  8. Prospects of Arbuscular Mycorrhiza in Sustainable Management of Root and Soil-Borne Diseases of Vegetable Crops

    Microsoft Academic Search

    M. Sharma; A. Gaur; Tanu; O. Sharma

    Vegetable crops are highly prone to a number of root and soil borne diseases causing great losses in yield and quality. Indiscriminate\\u000a use of fungicides and pesticides in controlling the diseases has polluted the environment and produce. Thus, there is need\\u000a of proper management of these diseases at reduced doses of pesticides to sustain the vegetable production. Biological control\\u000a of

  9. Marble waste and pig manure amendments decrease metal availability, increase soil quality and facilitate vegetation development in bare mine soils

    NASA Astrophysics Data System (ADS)

    Zornoza, Raúl; Faz, Ángel; Martínez-Martínez, Silvia; Acosta, José A.; Gómez, M. Dolores; Ángeles Muñoz, M.

    2013-04-01

    In order to bring out a functional and sustainable land use in a highly contaminated mine tailing, firstly environmental risks have to be reduced or eliminated by suitable reclamation activities. Tailing ponds pose environmental hazards, such as acidity and toxic metals reaching to waters through wind and water erosions and leaching. As a consequence, soils have no vegetation and low soil organic matter and nutrients. Various physicochemical and biochemical properties, together with exchangeable metals were measured before, 6 months and 12 months after the application of marble waste and pigs manure as reclamation strategy in a tailing pond from SE Spain to reduce hazards for environment and human health. Three months after the last addition of amendments, eight different native shrub species where planted for phytostabilization. Results showed the pH increased up to neutrality. Aggregates stability, organic carbon, total nitrogen, cation exchange capacity, bioavailable phosphorus and potassium, microbial biomass and microbial activity increased with the application of the amendments, while exchangeable metals drastically decreased (~90%). After one year of plantation, only 20% planted species died, with a high growth of survivals reaching flowering and fructification. This study confirms the high effectiveness of initial applications of marble wastes together with pig manure and plantation of shrub species to initialize the recovery of the ecosystem in bare mine soils under Mediterranean semiarid conditions. Key Words: pig manure, marble waste, heavy metals, mine soil. Acknowledgements This work has been funded by the European Union LIFE+ project MIPOLARE (LIFE09 ENV/ES/000439). J.A. Acosta acknowledges a "Saavedra Fajardo" contract from Comunidad Autónoma de Murcia (Spain)

  10. Impact of droughts on the carbon cycle in European vegetation: a probabilistic risk analysis using six vegetation models

    NASA Astrophysics Data System (ADS)

    Van Oijen, M.; Balkovi, J.; Beer, C.; Cameron, D. R.; Ciais, P.; Cramer, W.; Kato, T.; Kuhnert, M.; Martin, R.; Myneni, R.; Rammig, A.; Rolinski, S.; Soussana, J.-F.; Thonicke, K.; Van der Velde, M.; Xu, L.

    2014-11-01

    We analyse how climate change may alter risks posed by droughts to carbon fluxes in European ecosystems. The approach follows a recently proposed framework for risk analysis based on probability theory. In this approach, risk is quantified as the product of hazard probability and ecosystem vulnerability. The probability of a drought hazard is calculated here from the Standardized Precipitation-Evapotranspiration Index (SPEI). Vulnerability is calculated from the response to drought simulated by process-based vegetation models. We use six different models: three for generic vegetation (JSBACH, LPJmL, ORCHIDEE) and three for specific ecosystems (Scots pine forests: BASFOR; winter wheat fields: EPIC; grasslands: PASIM). The periods 1971-2000 and 2071-2100 are compared. Climate data are based on gridded observations and on output from the regional climate model REMO using the SRES A1B scenario. The risk analysis is carried out for ~ 18 000 grid cells of 0.25 × 0.25° across Europe. For each grid cell, drought vulnerability and risk are quantified for five seasonal variables: net primary and ecosystem productivity (NPP, NEP), heterotrophic respiration (Rh), soil water content and evapotranspiration. In this analysis, climate change leads to increased drought risks for net primary productivity in the Mediterranean area: five of the models estimate that risk will exceed 15%. The risks increase mainly because of greater drought probability; ecosystem vulnerability will increase to a lesser extent. Because NPP will be affected more than Rh, future carbon sequestration (NEP) will also be at risk predominantly in southern Europe, with risks exceeding 0.25 g C m-2 d-1 according to most models, amounting to reductions in carbon sequestration of 20 to 80%.

  11. Impact of droughts on the C-cycle in European vegetation: a probabilistic risk analysis using six vegetation models

    NASA Astrophysics Data System (ADS)

    Van Oijen, M.; Balkovi?, J.; Beer, C.; Cameron, D.; Ciais, P.; Cramer, W.; Kato, T.; Kuhnert, M.; Martin, R.; Myneni, R.; Rammig, A.; Rolinski, S.; Soussana, J.-F.; Thonicke, K.; Van der Velde, M.; Xu, L.

    2014-06-01

    We analyse how climate change may alter risks posed by droughts to carbon fluxes in European ecosystems. The approach follows a recently proposed framework for risk analysis based on probability theory. In this approach, risk is quantified as the product of hazard probability and ecosystem vulnerability. The probability of a drought hazard is calculated here from the Standardised Precipitation Evapotranspiration Index. Vulnerability is calculated from the response to drought simulated by process-based vegetation models. Here we use six different models: three for generic vegetation (JSBACH, LPJmL, ORCHIDEE) and three for specific ecosystems (Scots pine forests: BASFOR; winter wheat fields: EPIC; grasslands: PASIM). The periods 1971-2000 and 2071-2100 are compared. Climate data are based on observations and on output from the regional climate model REMO using the SRES A1B scenario. The risk analysis is carried out for ∼22 000 grid cells of 0.25° × 0.25° across Europe. For each grid cell, drought vulnerability and risk are quantified for five seasonal variables: net primary and ecosystem productivity (NPP, NEP), heterotrophic respiration (RH), soil water content and evapotranspiration. Climate change is expected to lead to increased drought risks to net primary productivity in the Mediterranean area: five of the models estimate that risk will exceed 15%. The risks will increase mainly because of greater drought probability; ecosystem vulnerability will increase to lesser extent. Because NPP will be affected more than RH, future C-sequestration (NEP) will also be at risk predominantly in southern Europe, with risks exceeding 0.25 g C m-2 d-1 according to most models, amounting to reductions in carbon sequestration of 20 to 80%.

  12. Exploring the response of West Siberian wetland methane emissions to potential future changes in climate, vegetation, and soil microbial metabolism

    NASA Astrophysics Data System (ADS)

    Bohn, Theodore; Kaplan, Jed; Lettenmaier, Dennis

    2015-04-01

    Methane emissions from northern peatlands depend strongly on environmental conditions, wetland plant species assemblages (via root zone oxidation and plant-aided transport), and soil microbial behavior (via metabolic pathways). While the responses of wetland methane emissions to potential future climate change have been extensively explored, the effects of future changes in plant species and soil microbial metabolism are not as well studied. We ran the Variable Infiltration Capacity (VIC) land surface model over the West Siberian Lowland (WSL), with methane emissions parameters that vary spatially with dominant plant species, and forced with outputs from 32 CMIP5 models for the RCP4.5 scenario. We compared the effects of changes in climate and vegetation (in terms of both leaf area index and species abundances) on predicted wetland CH4 emissions for the period 2071-2100, relative to the period 1981-2010. We also explored possible acclimatization of soil microbial communities to these changes. We evaluated the effects of climate change, potential northward migration of plant species, and potential microbial acclimatization on end-of-century methane emissions over the WSL, in terms of both total annual emissions and the spatial distribution of emissions. Our results suggest that, while microbial acclimatization mitigates the effects of warmer temperatures, the northward migration of plant species enhances the response to warming (due to plant-aided transport), and additionally shifts the location of maximal emissions northward, where the possible release of ancient carbon with permafrost thaw is a concern. Our work indicates the importance of better constraining the responses of wetland plants and soil microbial communities to changes in climate as they are critical determinants of the region's future methane emissions.

  13. Increment of iodine content in vegetable plants by applying iodized fertilizer and the residual characteristics of iodine in soil.

    PubMed

    Weng, Huan-Xin; Weng, Jing-Ke; Yan, Ai-Lan; Hong, Chun-Lai; Yong, Wen-Bin; Qin, Ya-Chao

    2008-01-01

    As a new attempt to control iodine deficiency disorder (IDD), we explored a method of iodine supplementation by raising the iodine content in vegetables. When grown in the soil supplemented with iodized fertilizer, the three experimental plant species (cucumber, aubergine, and radish) show increasing iodine levels in both leaf and fruit/rhizome tissues as the iodine content added in soil increases. Excessive iodine added to soil can be toxic to plants, whereas the tolerance limit to excessive iodine varies in the three plant species tested. The migration and volatilization of iodine in soil is correlated with the properties of the soil used. The residual iodine in soil increases as the iodine added to soil increases. The diatomite in the iodized fertilizer helps to increase the durability of the iodized fertilizer. This study potentially provides a safe and organic iodine supplementation method to control IDD. PMID:18265951

  14. Incorporating grassland management in a global vegetation model

    NASA Astrophysics Data System (ADS)

    Chang, Jinfeng; Viovy, Nicolas; Vuichard, Nicolas; Ciais, Philippe; Wang, Tao; Cozic, Anne; Lardy, Romain; Graux, Anne-Isabelle; Klumpp, Katja; Martin, Raphael; Soussana, Jean-François

    2013-04-01

    Grassland is a widespread vegetation type, covering nearly one-fifth of the world's land surface (24 million km2), and playing a significant role in the global carbon (C) cycle. Most of grasslands in Europe are cultivated to feed animals, either directly by grazing or indirectly by grass harvest (cutting). A better understanding of the C fluxes from grassland ecosystems in response to climate and management requires not only field experiments but also the aid of simulation models. ORCHIDEE process-based ecosystem model designed for large-scale applications treats grasslands as being unmanaged, where C / water fluxes are only subject to atmospheric CO2 and climate changes. Our study describes how management of grasslands is included in the ORCHIDEE, and how management affects modeled grassland-atmosphere CO2 fluxes. The new model, ORCHIDEE-GM (Grassland Management) is capable with a management module inspired from a grassland model (PaSim, version 5.0), of accounting for two grassland management practices (cutting and grazing). The evaluation of the results of ORCHIDEE-GM compared with those of ORCHIDEE at 11 European sites equipped with eddy covariance and biometric measurements, show that ORCHIDEE-GM can capture realistically the cut-induced seasonal variation in biometric variables (LAI: Leaf Area Index; AGB: Aboveground Biomass) and in CO2 fluxes (GPP: Gross Primary Productivity; TER: Total Ecosystem Respiration; and NEE: Net Ecosystem Exchange). But improvements at grazing sites are only marginal in ORCHIDEE-GM, which relates to the difficulty in accounting for continuous grazing disturbance and its induced complex animal-vegetation interactions. Both NEE and GPP on monthly to annual timescales can be better simulated in ORCHIDEE-GM than in ORCHIDEE without management. At some sites, the model-observation misfit in ORCHIDEE-GM is found to be more related to ill-constrained parameter values than to model structure. Additionally, ORCHIDEE-GM is able to simulate forage yield, herbage consumption, animal products (e.g. milk), animal respiration and animal CH4 emissions. These new variables combined with organic C fertilizer applied on the field could provide a more complete view of grasslands C fluxes for applications of the model on a grid. The 11 site simulations of this study show that European grasslands generally are C sinks (positive NBP). At grazed grasslands, both C export in the form of milk production and CH4 emissions by animals only consist a minor part of net primary production (NPP), and this means that NBP mainly depends on NPP. On the contrary, the cut sites accumulate less C in soils because a large part of NPP has been exported as forage production. Furthermore, theoretically potential of productivity and livestock density in European grassland can be predicted by ORCHIDEE-GM, based on the strategy modeling of the optimal livestock density and management change.

  15. Radionuclide concentrations in soils and vegetation at radioactive-waste disposal Area G during the 1996 growing season. Progress report

    SciTech Connect

    Fresquez, P.R.; Vold, E.L.; Naranjo, L. Jr.

    1997-07-01

    Soil and overstory and understory vegetation (washed and unwashed) collected at eight locations within and around Area G--a low-level radioactive solid-waste disposal facility at Los Alamos National laboratory--were analyzed for {sup 3}H, {sup 90}Sr, {sup 238}Pu, {sup 239}Pu, {sup 137}Cs, {sup 234}U, {sup 235}U, {sup 238}U, {sup tot}U, {sup 228}Ac, {sup 214}Bi, {sup 60}Co, {sup 40}K, {sup 54}Mn, {sup 22}Na, {sup 214}Pb, and {sup 208}Tl. Also, heavy metals (Ag, As, Ba, Be, Cd, Cr, Hg, Ni, Pb, Sb, Se, and Tl) in soil and vegetation were determined. In general, most radionuclide concentrations, with the exception of {sup 3}H and {sup 239}Pu, in soils and washed and unwashed overstory and understory vegetation collected from within and around Area G were within upper limit background concentrations. Tritium was detected as high as 14,744 pCi mL{sup {minus}1} in understory vegetation collected from transuranic (TRU) waste pad {number_sign}4, and the TRU waste pad area contained the highest levels of {sup 239}Pu in soils and in understory vegetation as compared to other areas at Area G.

  16. A land surface ¹?C transfer model and numerical experiments on belowground ¹?C accumulation and its impact on vegetation ¹?C level.

    PubMed

    Ota, Masakazu; Nagai, Haruyasu; Koarashi, Jun

    2012-05-01

    A model simulating transport and exchange for ¹?C (or ¹?CO?) in a land surface ecosystem was developed and the belowground ¹?C accumulation and its impact on vegetation ¹?C accumulation at a hypothetical cultivated field were studied with the model through numerical experiments. The developed model involved physical ¹?CO? transport in surface atmosphere and soil and physiological ¹?CO? exchanges in leaves, and was incorporated into a dynamical model (SOLVEG-II) that calculates transport and exchange for heat, water and CO?. The model was tested through a simulation of an existing-experiment on an acute exposure of grape plants to ¹?CO?. The calculated ¹?C amount in leaves agreed with the observations within a factor of 1.7. A hypothetical scenario used for the numerical experiments considered an annual ¹?C input into surface soil layers via ¹?C-enriched foliage or root litter under a continually heightened atmospheric ¹?CO? concentration. The specific activity of ¹?C in the surface soil layers increased with time and several decades after the start of accumulation it eventually converged to eight times the initial specific activity. At this equilibrium state, the increased belowground ¹?CO? production enhanced the atmospheric ¹?CO? level and, consequently, ¹?CO? uptake by vegetation increased to 1.1 times the control calculated without belowground ¹?C accumulation. The model results also demonstrated that ¹?C accumulated in soil can maintain an enhanced vegetation ¹?C level for at least several decades even after the end of accumulation. PMID:22370649

  17. Radionuclide transport from soil to air, native vegetation, kangaroo rats and grazing cattle on the Nevada test site

    SciTech Connect

    Gilbert, R.O.; Shinn, J.H.; Essington, E.H.; Tamura, T.; Romney, E.M.; Moor, K.S.; O'Farrell, T.P.

    1988-12-01

    Between 1970 and 1986 the Nevada Applied Ecology Group (NAEG), U.S. Department of Energy, conducted environmental radionuclide studies at weapons-testing sites on or adjacent to the Nevada Test Site. In this paper, NAEG studies conducted at two nuclear (fission) sites (NS201, NS219) and two nonnuclear (nonfission) sites (Area 13 (Project 57) and Clean Slate 2) are reviewed, synthesized and compared regarding (1) soil particle-size distribution and physical-chemical characteristics of 239 + 240Pu-bearing radioactive particles, (2) 239 + 240Pu resuspension rates and (3) transuranic and fission-product radionuclide transfers from soil to native vegetation, kangaroo rats and grazing cattle. The data indicate that transuranic radionuclides were transferred more readily on the average from soil to air, the external surfaces of native vegetation and to tissues of kangaroo rats at Area 13 than at NS201 or NS219. The 239 + 240Pu resuspension factor for undisturbed soil at Area 13 was three to four orders-of-magnitude larger than at NS201 and NS219, the geometric mean (GM) vegetation-over-soil 239 + 240Pu concentration ratio was from ten to 100 times larger than at NS201, and the GM GI-over-soil, carcass-over-soil and pelt-over-soil 239 + 240Pu ratios for kangaroo rats were about ten times larger than at NS201. These results are consistent with the finding that Area 13, compared with NS201 or NS219, has a higher percentage of radioactivity associated with