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Satellite observed widespread decline in Mongolian grasslands largely due to overgrazing

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dc.creator Hilker, Thomas
dc.creator Natsagdorj, Enkhjargal
dc.creator Waring, Richard H.
dc.creator Lyapustin, Alexei
dc.creator Wang, Yujie
dc.date.accessioned 2013-08-29T17:06:21Z
dc.date.available 2013-08-29T17:06:21Z
dc.date.issued 2013-12-19
dc.identifier.citation Hilker, T., Natsagdorj, E., Waring, R. H., Lyapustin, A., & Wang, Y. (2014). Satellite observed widespread decline in Mongolian grasslands largely due to overgrazing. Global Change Biology, 20(2), 418-428. doi:10.1111/gcb.12365 en_US
dc.identifier.uri http://hdl.handle.net/1957/42251
dc.description To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by John Wiley & Sons Ltd. and can be found at: http://onlinelibrary.wiley.com/journal/10.1111/%28ISSN%291365-2486. The accepted manuscript is also provided. en_US
dc.description.abstract The Mongolian Steppe is one of the largest remaining grassland ecosystems. Recent studies have reported widespread decline of vegetation across the steppe and about 70% of this ecosystem is now considered degraded. Among the scientific community there has been an active debate about whether the observed degradation is related to climate, or over-grazing, or both. Here, we employ a new atmospheric correction and cloud screening algorithm (MAIAC) to investigate trends in satellite observed vegetation phenology. We relate these trends to changes in climate and domestic animal populations. A series of harmonic functions is fitted to Moderate Resolution Imaging Spectroradiometer (MODIS) observed phenological curves to quantify seasonal and inter-annual changes in vegetation. Our results show a widespread decline (of about 12% on average) in MODIS observed normalized difference vegetation index (NDVI) across the country but particularly in the transition zone between grassland and the Gobi desert, where recent decline was as much as 40% below the 2002 mean NDVI. While we found considerable regional differences in the causes of landscape degradation, about 80% of the decline in NDVI could be attributed to increase in livestock. Changes in precipitation were able to explain about 30% of degradation across the country as a whole but up to 50% in areas with denser vegetation cover (P < 0.05). Temperature changes, while significant, played only a minor role (r² = 0.10, p < 0.05). Our results suggest that the cumulative effect of overgrazing is a primary contributor to the degradation of the Mongolian steppe and is at least partially responsible for desertification reported in previous studies. en_US
dc.description.sponsorship We would like to thank Dr. Paul Doescher (Oregon State University) for providing funding for Ms. Natsagdorj to work on this project. RHW contributions to this paper are an extension of his research supported by NASA grant NNX11A029G. The work of Drs. Lyapustin and Wang was supported by the NASA Science of Terra and Aqua Program. en_US
dc.language.iso en_US en_US
dc.publisher John Wiley & Sons Ltd. en_US
dc.relation.ispartofseries Global Change Biology en_US
dc.subject Grassland decline
dc.subject MAIAC
dc.subject MODIS
dc.subject Mongolia
dc.subject NDVI
dc.subject Over-grazing
dc.subject Time-series
dc.title Satellite observed widespread decline in Mongolian grasslands largely due to overgrazing en_US
dc.type Article en_US
dc.description.peerreview yes en_US
dc.identifier.doi 10.1111/gcb.12365

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