TY - JOUR
T1 - Divergent responses of vegetation cover in Southwestern US ecosystems to dry and wet years at different elevations
AU - Herrmann, Stefanie M.
AU - Didan, Kamel
AU - Barreto-Munoz, Armando
AU - Crimmins, Michael A.
N1 - Funding Information:
This work was supported by NASA EOS-MODIS grant number NNX14AI74G and NASA S-NPP-VIIRS cooperative agreement number NNX14AP69A (K Didan, PI). We thank the three anonymous reviewers for their valuable comments, which helped improve the quality of the manuscript.
Publisher Copyright:
© 2016 IOP Publishing Ltd.
PY - 2016/11/24
Y1 - 2016/11/24
N2 - In the semiarid Southwestern United States, prolonged drought conditions since the early 2000s have resulted in widespread declines of the vegetation productivity in this water-constrained ecosystem, as revealed by analyses of the Normalized Difference Vegetation Index (NDVI). However, the spatial pattern of the NDVI response to dry years is not uniform: a divergent response of NDVI to precipitation is observed between the low-lying desert and the high montane forests at elevations above 2,500 meter. We analyzed relationships between 15 years of Moderate Resolution Imaging Spectroradiometer (MODIS) NDVI and gridded climate data (PRISM) along elevation gradients at scales from regional to local. Our elevation-explicit analysis captures the transition from water-limited to temperature-limited ecosystems, with a sign-reversal in the correlation coefficient between precipitation and NDVI observed at about 2,500-3,000m altitude. We suggest warmer temperatures and less snow cover associated with drier years as explanations for high elevation gains in vegetation productivity during dry years.
AB - In the semiarid Southwestern United States, prolonged drought conditions since the early 2000s have resulted in widespread declines of the vegetation productivity in this water-constrained ecosystem, as revealed by analyses of the Normalized Difference Vegetation Index (NDVI). However, the spatial pattern of the NDVI response to dry years is not uniform: a divergent response of NDVI to precipitation is observed between the low-lying desert and the high montane forests at elevations above 2,500 meter. We analyzed relationships between 15 years of Moderate Resolution Imaging Spectroradiometer (MODIS) NDVI and gridded climate data (PRISM) along elevation gradients at scales from regional to local. Our elevation-explicit analysis captures the transition from water-limited to temperature-limited ecosystems, with a sign-reversal in the correlation coefficient between precipitation and NDVI observed at about 2,500-3,000m altitude. We suggest warmer temperatures and less snow cover associated with drier years as explanations for high elevation gains in vegetation productivity during dry years.
KW - MODIS
KW - NDVI
KW - US Southwest
KW - climate dynamics
KW - drought
KW - elevation gradient
KW - vegetation productivity
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U2 - 10.1088/1748-9326/11/12/124005
DO - 10.1088/1748-9326/11/12/124005
M3 - Article
AN - SCOPUS:85008156853
SN - 1748-9318
VL - 11
JO - Environmental Research Letters
JF - Environmental Research Letters
IS - 12
M1 - 124005
ER -