نتایج جستجو برای: soil and vegetation

تعداد نتایج: 16870582  

2000

Termites are the most important soil fauna in the Sahelian zone of Africa, intensely interacting with the soil. Both the biotic and abiotic state of the soil affect the termite population and activity. The construction by termites of nests, gallery systems or sheetings from soil or from a mixture of soil and other material within the soil horizons or on the soil surface affect the physical and ...

2011
Kamlesh Jangid Mark A. Williams Alan J. Franzluebbers Thomas M. Schmidt David C. Coleman William B. Whitman

The response of soil microbial communities following changes in land-use is governed by multiple factors. The objectives of this study were to investigate (i) whether soil microbial communities track the changes in aboveground vegetation during succession; and (ii) whether microbial communities return to their native state over time. Two successional gradients with different vegetation were stu...

2008
M. Sànchez-Marrè J. Béjar M. Pause M. Volk K. Schulz

Spatial distributed information of isochronal surface soil moisture is very important to compensate the inaccuracy of initial conditions and the uncertainty of parameters in hydrological models at the landscape scale. In this paper the conceptual procedure to derive spatial distributed surface soil moisture values from synthetic aperture radar data by using ancillary optical remote sensing data...

2007
Marilyn D. Walker Donald A. Walker Kaye R. Everett Susan K. Short MARILYN D. WALKER

The hypothesized presence of large regions of grass and forb-dominated "steppe tundra" across Alaska and Siberia during the Pleistocene glacial epochs has led to a search for modern analogs. Evidence is presented for the presence of steppe vegetation on south-facing slopes and summits of pingos within the central Arctic Coastal Plain of Alaska. Vegetation, floristics, soils, and climatic factor...

2015
Zhi Chen Guirui Yu Jianping Ge Qiufeng Wang Xianjin Zhu Zhiwei Xu

Climate, vegetation, and soil characteristics play important roles in regulating the spatial variation in carbon dioxide fluxes, but their relative influence is still uncertain. In this study, we compiled data from 241 eddy covariance flux sites in the Northern Hemisphere and used Classification and Regression Trees and Redundancy Analysis to assess how climate, vegetation, and soil affect the ...

2009
V. K. Gupta Raj Rishi

Dielectric constant values of the samples of soil of Alwar (at various moist states) have been calculated using wave guide cell method at a single microwave frequency 9.78 GHz at 33C. The Backscattering coefficients for rough and bare soil surfaces 0 soil σ are calculated by Small Perturbation Model (SPM). Fresnal reflectivity of the soil surfaces which is an input parameter for SPM is calculat...

2001
FEI CHEN JIMY DUDHIA

This paper addresses and documents a number of issues related to the implementation of an advanced land surface–hydrology model in the Penn State–NCAR fifth-generation Mesoscale Model (MM5). The concept adopted here is that the land surface model should be able to provide not only reasonable diurnal variations of surface heat fluxes as surface boundary conditions for coupled models, but also co...

Journal: :مرتع و آبخیزداری 0
سید حمزه حسینی کهنوج دانشجوی کارشناسی ارشد مرتع داری دانشکدة منابع طبیعی دانشگاه تربیت مدرس رضا عرفان زاده دانشیار گروه مرتع داری دانشکدة منابع طبیعی دانشگاه تربیت مدرس حسین آذرنیوند استاد گروه احیای مناطق خشک و کوهستانی، دانشکدة منابع طبیعی دانشگاه تهران

this study aimed to investigate the effect of habitat kind on soil seed bank characteristics viz. density diversity, richness and similarity between seed bank and above ground vegetation. two different habitats (grassland and forest) were selected in vaz, mazandaran province. the grassland habitat located in the upper end of the forest habitat, adjacent to each other. then in each habitat, 7 tr...

Journal: :Physical review. E, Statistical, nonlinear, and soft matter physics 2008
R Vezzoli C De Michele H Pavlopoulos R J Scholes

In drylands the soil water availability is a key factor ruling the architecture of the ecosystem. The soil water reflects the exchanges of water among soil, vegetation, and atmosphere. Here, a dryland ecosystem is investigated through the analysis of the local interactions between soil water and vegetation forced by rainfall having seasonal and stochastic occurrence. The evolution of dryland ec...

2011
EDUARDO DE SÁ ALAN RODRIGO PANOSSO FELIPE N.B. SIMAS

Soil CO2 emission is an important part of the terrestrial carbon cycling and is influenced by several factors, such as type and distribution of vegetation. In this work we evaluated the spatial variability of soil CO2 emission in terrestrial ecosystems of maritime Antarctica, under two contrasting vegetation covers: 1) grass areas of Deschampsia antarctica Desv., and 2) moss carpets of Sanionia...

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