A5088635348- Remote Sensing in Agriculture
- Plant Water Relations and Carbon Dynamics
- Land Use and Ecosystem Services
- Remote Sensing and LiDAR Applications
- Atmospheric and Environmental Gas Dynamics
- Rangeland Management and Livestock Ecology
- Climate variability and models
- African Botany and Ecology Studies
- Urban Heat Island Mitigation
- Ecology and Vegetation Dynamics Studies
- Soil Geostatistics and Mapping
- Remote Sensing and Land Use
- Cinema and Media Studies
- Soil erosion and sediment transport
- Soil Moisture and Remote Sensing
- Hydrology and Watershed Management Studies
- Species Distribution and Climate Change
- Forest ecology and management
- Leaf Properties and Growth Measurement
- Botany and Plant Ecology Studies
- Solar Radiation and Photovoltaics
- Calibration and Measurement Techniques
- Wildlife Ecology and Conservation
- Conservation, Biodiversity, and Resource Management
- Rangeland and Wildlife Management
University of Maryland, College Park
2008-2021
Temple College
2017
National Wildlife Federation
2017
National Institute for Environmental Studies
2016
University of Arizona
2012
Texas A&M University
2010-2012
South Dakota State University
2007
Goddard Space Flight Center
1989-2005
Center For Remote Sensing (United States)
1995-2000
Virginia Tech
1999
Net primary production (NPP), the difference between CO2 fixed by photosynthesis and lost to autotrophic respiration, is one of most important components carbon cycle. Our goal was develop a simple regression model estimate global NPP using climate land cover data. Approximately 5600 data points with observed mean annual NPP, class, precipitation, temperature were compiled. Precipitation better correlated than temperature, it explained much more variability in for grass- or shrub-dominated...
Abstract Field measurements of primary production in semi-arid grasslands three Sahelian countries over a period 8 years are analysed conjunction with multitemporal sums vegetation indices derived from the NOAA spacecraft's advanced very high resolution radiometer (AVHRR). The results demonstrate that there is strong linear relationship between satellite observations and seasonal range 0-3000 kg ha−. confidence intervals estimation were ±61-161
Abstract Desertification is regarded as one of the major global environmental problems 20th century and African Sahel often quoted most seriously affected region. Previous attempts to map occurrence severity desertification in have been unsatisfactory, mainly because lack any readily measured, objective indicators. We explore here properties ratio net primary production (NPP) precipitation – rain‐use efficiency (RUE) calculated from remotely sensed vegetation indices rain gauge data....
Abstract. The Hydrologic Atmospheric Pilot EXperiment in the Sahel (HAPEX-Sahel) was carried out Niger, West Africa, during 1991 - 1992, with an intensive observation period (IOP) August October 1992. It aims at improving parameterization of land surface atmosphere interactions Global Circulation Model (GCM) gridbox scale. experiment combines remote sensing and ground based measurements hydrological meteorological modelling to develop aggregation techniques for use large scale estimates...
The goal of NASA's land long term data record (LTDR) project is to produce a consistent set from the AVHRR and MODIS instruments for climate studies. will create daily surface reflectance normalized difference vegetation index (NDVI) products at resolution 0.05deg, which identical modeling grid (CMG) used EOS Terra Aqua. Higher order such as burned area, temperature, albedo, bidirectional distribution function (BRDF) correction, leaf area (LAI), fraction photosynthetically active radiation...
Images are presented that show the mean and coefficient of variation nine years (1981-1989) NOAA AVHRR normalized difference vegetation index (NDVI) data for growing season (July-October) in Africa, north equator. The NDVI is represented by image shows large Sahelian between years. It concluded these images illustrate some aspects perspective being brought to regional continental scale processes coarse resolution satellite sensors potential provide consistent, long-term datasets.
We studied crop harvested yield, as recorded in national agricultural statistics, to estimate net primary production (NPP) regions where most of the land area is sown with a few, well-studied crops. estimated magnitudes and interannual variations NPP croplands U.S. Midwest using yield data obtained from National Agricultural Statistics Service (NASS). Total NPP, including estimates above- belowground components, was calculated harvested-yield by (1) conversion reporting units product...
Abstract Normalized difference vegetation index data obtained from polar-orbiting meteorological satellites were used to compare the growing or rainy seasons of 1984 and 1985 for Sahelian zone Africa. A substantial was found between these two years, with generally having higher normalized values indicating levels primary production in than 1984. 1 km compared Senegal, Mali, Niger Sudan, 7 sub-Saharan The qualitative comparison suggests use similar assist centralized monitoring rangeland...
Evidence is presented that exchanges of water and energy between the vegetation atmosphere play an important role in east Asian West African monsoon development are among most mechanisms governing monsoon. The results were obtained by conducting simulations for five months 1987 using a general circulation model (GCM) coupled with two different land surface parameterizations, without explicit representations, referred to as GCM/vegetation GCM/soil, respectively. models produced similar at...
Abstract The interest in national terrestrial ecosystem carbon budgets has been increasing because the Kyoto Protocol included some sinks a legally binding framework for controlling greenhouse gases emissions. Accurate quantification of sink must account interannual variations associated with climate variability and change. This study used process‐based biogeochemical model remote sensing‐based production efficiency to estimate net primary (NPP), soil heterotrophic respiration (HR), (NEP)...
Abstract In semiarid regions the ratio of annual net primary production to precipitation, rain‐use efficiency (RUE), has been used as an index desertification. a recent publication ( Hein & de Ridder, 2006 ) it was proposed that incorrect understanding relationship between RUE and rainfall led misinterpretation satellite record desertification in African Sahel. Here, we examine this suggestion show that, contrary Ridder's statement, studies Sahelian have reported increases, decreases,...
Ecological modellers are preparing to address how the biosphere may respond decadalto century-scale changes in Earth's environmental system. This endeavour has revealed a question for which no immediate answer is readily available: do ecosystems dynamically climate variations? explored with 10 + year record of global vegetation dynamics recorded by satellite remote sensing observatory. It found that average geography observed patterns well explained continental-scale climatology both North...
Lactuca serriola L. seedlings emerge throughout the year with germination peaks in early winter and late spring. These are followed closely by high levels of mortality which together produce an almost constant plant density. Plants from seeds germinate months more than those spring summer this is considered to be associated duration rosette stage. However, increased fecundity former partially annulled their higher mortality. It concluded that winter-germinated plants main seed producers...