Open AccessReductions in productivity due to land degradation in the drylands of the southwestern United States
Author(s) -
Noojipady Praveen,
Prince Stephen D.,
Rishmawi Khaldoun
Publication year - 2015
Publication title -
ecosystem health and sustainability
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.956
H-Index - 21
ISSN - 2332-8878
DOI - 10.1890/ehs15-0020.1
Subject(s) - land degradation , environmental science , primary production , normalized difference vegetation index , grassland degradation , grassland , land cover , moderate resolution imaging spectroradiometer , land use , vegetation (pathology) , rangeland , physical geography , land management , productivity , hydrology (agriculture) , satellite , geography , climate change , ecosystem , agroforestry , agronomy , ecology , medicine , engineering , pathology , geotechnical engineering , biology , aerospace engineering , macroeconomics , economics
Dryland degradation has long been recognized at regional, national, and global scales, yet there are no objective assessments of its location and severity. An assessment of reductions in net primary production (NPP) due to dryland degradation in the southwestern United States is reported. The local NPP scaling (LNS) approach was applied to map the extent and magnitude of degradation. LNS seeks to identify 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 degradation. Twelve years were analyzed (2000–2011), using Normalized Difference Vegetation Index (NDVI) data (250 m) from the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite‐borne multispectral sensor. The results indicated that the total NPP reductions in the study area were about 35.9 ± 4.7 Tg 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 weather. In comparison with other cover types, forested land generally had higher NPP reduction per unit area. The 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 U.S. Forest Service. 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.