排序方式: 共有7条查询结果,搜索用时 15 毫秒
1
1.
David J Mildrexler Maosheng Zhao Faith Ann Heinsch Steven W Running 《Ecological applications》2007,17(1):235-250
The timing, location, and magnitude of major disturbance events are currently major uncertainties in the global carbon cycle. Accurate information on the location, spatial extent, and duration of disturbance at the continental scale is needed to evaluate the ecosystem impacts of land cover changes due to wildfire, insect epidemics, flooding, climate change, and human-triggered land use. This paper describes an algorithm developed to serve as an automated, economical, systematic disturbance detection index for global application using Moderate Resolution Imaging Spectroradiometer (MODIS)/Aqua Land Surface Temperature (LST) and Terra/MODIS Enhanced Vegetation Index (EVI) data from 2003 to 2004. The algorithm is based on the consistent radiometric relationship between LST and EVI computed on a pixel-by-pixel basis. We used annual maximum composite LST data to detect fundamental changes in land-surface energy partitioning, while avoiding the high natural variability associated with tracking LST at daily, weekly, or seasonal time frames. Verification of potential disturbance events from our algorithm was carried out by demonstration of close association with independently confirmed, well-documented historical wildfire events throughout the study domain. We also examined the response of the disturbance index to irrigation by comparing a heavily irrigated poplar tree farm to the adjacent semiarid vegetation. Anomalous disturbance results were further examined by association with precipitation variability across areas of the study domain known for large interannual vegetation variability. The results illustrate that our algorithm is capable of detecting the location and spatial extent of wildfire with precision, is sensitive to the incremental process of recovery of disturbed landscapes, and shows strong sensitivity to irrigation. Disturbance detection in areas with high interannual variability of precipitation will benefit from a multiyear data set to better separate natural variability from true disturbance. 相似文献
2.
This paper introduces an innovative modelling strategy aimed at simulating the main terms of net forest carbon budget (net primary production, NPP and net ecosystem exchange, NEE) in Tuscany (Central Italy). The strategy is based on the preliminary calibration and application of parametric and bio-geochemical models (C-Fix and BIOME-BGC, respectively), which simulate the behaviour of forest ecosystems close to equilibrium condition (climax). Next, the ratio of actual over-potential tree volume is computed as an indicator of ecosystem distance from climax and is combined with the model outputs to estimate the NPP and NEE of real forests. The per-pixel application of the new modelling strategy was made possible by the collection of several data layers (maps of forest type and volume, daily meteorological data and monthly normalized difference vegetation index (NDVI) images for the years 1999–2003) which served to characterize the eco-climatic and forest features of the region. The obtained estimates of forest NPP and NEE were evaluated against ground measurements of accumulated woody biomass and net carbon exchange. The results of these experiments testify the good potential of the proposed strategy and indicate some problem areas which should be the subject of future research. 相似文献
3.
Zirui Zhang Chenhang Zhang Huan Liu Feng Bin Xiaolin Wei Running Kang Shaohua Wu Wenming Yang Hongpeng Xu 《Frontiers of Environmental Science & Engineering》2023,17(9):109
4.
Dengsheng Lu Xiaofeng Xu Hanqin Tian Emilio Moran Maosheng Zhao Steven Running 《Environmental management》2010,46(3):404-410
Net primary productivity (NPP) is one of the major ecosystem products on which human societies rely heavily. However, rapid
urban sprawl and its associated dense population and economic conditions have generated great pressure on natural resources,
food security, and environments. It is valuable to understand how urban expansion and associated demographic and economic
conditions affect ecosystem functions. This research conducted a case study in Southeastern China to examine the impacts of
urban expansion and demographic and economic conditions on NPP. The data sources used in research include human settlement
developed through a combination of MODIS, DMSP-OLS and Landsat ETM+ images, the annual NPP from MODIS, and the population
and gross domestic product (GDP) from the 2000 census data. Multiple regression analysis and nonlinear regression analysis
were used to examine the relationships of NPP with settlement, population and GDP. This research indicates that settlement,
population and GDP have strongly negative correlation with NPP in Southeastern China, but the outcomes were nonlinear when
population or GDP reached certain thresholds. 相似文献
5.
Daniel B. Fagre Peter L. Comanor Joseph D. White F Richard Hauer Steven W. Running 《Journal of the American Water Resources Association》1997,33(4):755-765
ABSTRACT: We have developed an approach which examines ecosystem function and the potential effects of climatic shifts. The Lake McDonald watershed of Glacier National Park was the focus for two linked research activities: acquisition of baseline data on hydrologic, chemical and aquatic organism attributes that characterize this pristine northern rocky mountain watershed, and further developing the Regional Hydro-Ecosystem Simulation System (RHESSys), a collection of integrated models which collectively provide spatially explicit, mechanistically-derived outputs of ecosystem processes, including hydrologic outflow, soil moisture, and snow-pack water equivalence. In this unique setting field validation of RHESSys, outputs demonstrated that reasonable estimates of SWE and streamflow are being produced. RHESSys was used to predict annual stream discharge and temperature. The predictions, in conjunction with the field data, indicated that aquatic resources of the park may be significantly affected. Utilizing RHESSys to predict potential climate scenarios and response of other key ecosystem components can provide scientific insights as well as proactive guidelines for national park management. 相似文献
6.
Mapping and Modeling the Biogeochemical Cycling of Turf Grasses in the United States 总被引:6,自引:0,他引:6
Milesi C Running SW Elvidge CD Dietz JB Tuttle BT Nemani RR 《Environmental management》2005,36(3):426-438
Turf grasses are ubiquitous in the urban landscape of the United States and are often associated with various types of environmental
impacts, especially on water resources, yet there have been limited efforts to quantify their total surface and ecosystem
functioning, such as their total impact on the continental water budget and potential net ecosystem exchange (NEE). In this
study, relating turf grass area to an estimate of fractional impervious surface area, it was calculated that potentially 163,800
km2 (± 35,850 km2) of land are cultivated with turf grasses in the continental United States, an area three times larger than that of any irrigated
crop. Using the Biome-BGC ecosystem process model, the growth of warm-season and cool-season turf grasses was modeled at a
number of sites across the 48 conterminous states under different management scenarios, simulating potential carbon and water
fluxes as if the entire turf surface was to be managed like a well-maintained lawn. The results indicate that well-watered
and fertilized turf grasses act as a carbon sink. The potential NEE that could derive from the total surface potentially under
turf (up to 17 Tg C/yr with the simulated scenarios) would require up to 695 to 900 liters of water per person per day, depending
on the modeled water irrigation practices, suggesting that outdoor water conservation practices such as xeriscaping and irrigation
with recycled waste-water may need to be extended as many municipalities continue to face increasing pressures on freshwater. 相似文献
7.
Satellite Remote Sensing of Terrestrial Net Primary Production for the Pan-Arctic Basin and Alaska 总被引:2,自引:0,他引:2
J. S. Kimball M. Zhao K. C. McDonald S. W. Running 《Mitigation and Adaptation Strategies for Global Change》2006,11(4):783-804
We applied a terrestrial net primary production (NPP) model driven by satellite remote sensing observations of vegetation
properties and daily surface meteorology from a regional weather forecast model to assess NPP spatial and temporal variability
for the pan-Arctic basin and Alaska from 1982 to 2000. Our results show a general decadal trend of increasing NPP for the
region of approximately 2.7%, with respective higher (3.4%) and lower (2.2%) rates for North America and Eurasia. NPP is both
spatially and temporally dynamic for the region, driven largely by differences in productivity rates among major biomes and
temporal changes in photosynthetic canopy structure and spring and summer air temperatures. Mean annual NPP for boreal forests
was approximately 3 times greater than for Arctic tundra on a unit area basis and accounted for approximately 55% of total
annual carbon sequestration for the region. The timing of growing season onset inferred from regional network measurements
of atmospheric CO2 drawdown in spring was inversely proportional to annual NPP calculations. Our findings indicate that recent regional warming
trends in spring and summer and associated advances in the growing season are stimulating net photosynthesis and annual carbon
sequestration by vegetation at high latitudes, partially mitigating anthropogenic increases in atmospheric CO2. These results also imply that regional sequestration and storage of atmospheric CO2 is being altered, with potentially greater instability and acceleration of the carbon cycle at high latitudes. 相似文献
1