NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Collections About News Help Login
Back to Results
Satellite Observed Widespread Decline in Mongolian Grasslands Largely Due to OvergrazingThe Mongolian Steppe is one of the largest remaining grassland ecosystems. Recent studies have reported widespread decline of vegetation across the steppe and about 70 percent 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 overgrazing, 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 MODIS observed phenological curves to quantify seasonal and inter-annual changes in vegetation. Our results show a widespread decline (of about 12 percent on average) in MODIS observed NDVI across the country but particularly in the transition zone between grassland and the Gobi desert, where recent decline was as much as 40 percent below the 2002 mean NDVI. While we found considerable regional differences in the causes of landscape degradation, about 80 percent of the decline in NDVI could be attributed to increase in livestock. Changes in precipitation were able to explain about 30 percent of degradation across the country as a whole but up to 50 percent in areas with denser vegetation cover (p0.05). Temperature changes, while significant, played only a minor role (r20.10, p0.05). 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.
Document ID
20140010870
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
External Source(s)
doi:10.1111/gcb.12365
Authors
Hilker, Thomas (Oregon State Univ. Corvallis, OR, United States)
Natsagdorj, Enkhjargal (Mongolian National Univ. Ulan Bator, Mongolia)
Waring, Richard H. (Oregon State Univ. Corvallis, OR, United States)
Lyapustin, Alexei (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Wang, Yujie (Maryland Univ. Baltimore County Baltimore, MD, United States)
Date Acquired
August 20, 2014
Publication Date
February 1, 2014
Publication Information
Publication: Global Change Biology
Publisher: Wiley
Volume: 20
Issue: 2
Subject Category
Earth Resources And Remote Sensing
Report/Patent Number
GSFC-E-DAA-TN10903
Funding Number(s)
CONTRACT_GRANT: NNX11A029G
CONTRACT_GRANT: NNX10AT36A
Distribution Limits
Public
Copyright
Public Use Permitted.
Keywords
Mongolia
MAIAC
grassland decline

Related Records

There are no records associated with this record.
No Preview Available