Reductions in productivity due to land degradation in the drylands of the southwestern United States
作者机构：Department of Geographical SciencesUniversity of MarylandCollege Park Maryland 20742 USA Biospheric Sciences LaboratoryNASA/Goddard Space Flight CenterGreenbelt Maryland 20771 USA The Applied Research InstituteJerusalemP.O.Box 860Karm Mu'ammarKarkafeh StBethlehemPalestine
出 版 物：《Ecosystem Health and Sustainability》 (生态系统健康与可持续性（英文）)
年 卷 期：2015年第1卷第8期
页 面：14-29页
学科分类：0710[理学-生物学] 071001[理学-植物学] 07[理学]
主 题：degradation drylands ecosystem health MODIS NDVI NPP rangelands reference conditions southwestern United States.
摘 要：Dryland degradation has long been recognized at regional,national,and global scales,yet there are no objective assessments of its location and *** assessment of reductions in net primary production(NPP)due to dry land degradation in the southwestern United States is *** local NPP scaling(LNS)approach was applied to map the extent and magnitude of degrada *** seeks to identifty reference sites in which there is no degradation that can be used as a standard for comparison with other sites that share the same environment,except for *** years were analyzed(2000--2011),using Normalized Difference Vegetation Index(NDVI)data(250 m)from the Moderate Resolution Imaging Spectroradiometer(MODIS)satellite-borne multispectral *** results indicated that the total NPP reductions in the study area were about35.9±4.7Tg C/yr,which equates to 0.31±0.04 Mg C·ha^(-1)· yr^(-1).The NPP reductions in grassland-savanna and livestock grazing areas were large and mostly consistent between years in spite of large variations in overall NPP caused by differences in land-use,interannual variations in rainfall,and other aspects of *** comparison with other cover types,forested land generally had higher NPP reduction per unit *** maps also enable attribution of degradation from the finest management units to entire agencies,such as the Bureau of Land Management,which had 50%less production per unit area than the *** *** degradation within Native American land was low with total NPP reduction of about 2.41±0.24 Tg C/yr and unit area reduction of productivity of just 0.21±0.02 Mg C·ha^(-1)·yr^(-1),yet the percent reduction from potential was in equivalence with other land management agencies.
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