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MODIS‐derived NDVI Characterisation of Drought‐Induced Evergreen Dieoff in Western North America
Author(s) -
YUHAS ANDREW N.,
SCUDERI LOUIS A.
Publication year - 2009
Publication title -
geographical research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.695
H-Index - 47
eISSN - 1745-5871
pISSN - 1745-5863
DOI - 10.1111/j.1745-5871.2008.00557.x
Subject(s) - normalized difference vegetation index , geography , vegetation (pathology) , climate change , arid , physical geography , temperate climate , evergreen , evergreen forest , precipitation , climatology , environmental science , ecology , biology , geology , medicine , pathology , meteorology
Vegetation stress or mortality can be the result of many factors including drought‐induced water deficit, insect infestations and failures of, or fluctuations in, precipitation sources typical to an area. Reduction of cover and reduced health are identifiable in remotely‐sensed multispectral satellite images. A suite of images from NASA's MODIS sensor was used to calculate the Normalised Difference Vegetation Index (NDVI) during the 2000–2006 North American growing seasons. Fluctuations in NDVI over this period show a significant decline in vegetative health in the region with specific areas showing changes linked to moisture sources, prevailing wind patterns, slope aspect and solar radiation receipt. Ground‐truthing of these areas has confirmed the extent and magnitude of the dieoff signal. Historically, dieoff has been reversed through regeneration as climate conditions return to a normal regime. However, quantification of recent vegetative change in western North America suggests that the degree of change may be too severe for regrowth to occur and may have far‐reaching impacts on a scale unseen in modern times. The loss of vegetative habitat and native species in semi‐arid regions and lack of regeneration in these marginal ecosystems due to prolonged drought are growing global problems. Similar drought stress impacts on marginal ecotypes have also been observed in semi‐arid regions of Australia, South America, Asia and Africa. Observations of the spatial pattern of temperate forest vegetation globally can be used to develop a precise picture of vegetative health in these regions and how they are reacting to global climate change.