Geography
Document Type
Article
Abstract
Drought-induced vegetation declines have been reported across the globe and may have widespread implications for ecosystem composition, structure, and functions. Thus, it is critical to maximizing our understanding of how vegetation has responded to recent drought extremes. To date, most drought assessments emphasized the importance of drought intensity for vegetation responses. However, drought timing, duration, and repeat exposure all may be important aspects of ecosystem response with the potential for non-linear effects. Cumulative effects are one such phenomenon, representing the additional decline due to repeated exposure to drought, and indicating gradual loss of ecosystem resistance. This study quantifies the frequency and magnitude of cumulative effects among Australian ecosystems as they responded to the Millennium Drought. Three distinct biophysical variables derived from satellite remote sensing were analyzed, including fraction of photosynthetically absorbed radiation, photosynthetic vegetation cover, and canopy density derived from passive microwave data. Cumulative effects were detected in only 8%–20% of the fire-free landscape exposed to repeat or long-duration drought, and could be a statistical artifact. In those limited cases, they approximately doubled drought impacts on leaf abundance, canopy cover, and vegetation density. Cultivated lands and grasslands were the most susceptible to cumulative effects, losing resistance to recurrent droughts, but could be false discovery. Despite being relatively infrequent in forests and savannas, cumulative effects caused larger additional declines in these ecosystems. Overall, our study demonstrates that repeated exposure appears to have limited influence on the magnitude of drought impacts on canopy structure affecting only a few areas. © 2023. The Authors.
There is one additional file of supporting information, also available for download.
Publication Title
Journal of Geophysical Research: Biogeosciences
Publication Date
5-2023
Volume
128
Issue
5
ISSN
2169-8953
DOI
10.1029/2022JG006818
Keywords
Australian ecosystems, cumulative effects, Millenium Drought, repeated and prolonged drought, vegetation index, vegetation optical depth
Repository Citation
Jiao, Tong; Williams, Christopher A.; De Kauwe, Martin; and Medlyn, Belinda E., "Limited Evidence of Cumulative Effects From Recurrent Droughts in Vegetation Responses to Australia's Millennium Drought" (2023). Geography. 944.
https://commons.clarku.edu/faculty_geography/944
Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 4.0 International License.
Copyright
Published source must be acknowledged with citation: Jiao, Tong, et al. "Limited evidence of cumulative effects from recurrent droughts in vegetation responses to Australia’s Millennium Drought." Journal of Geophysical Research: Biogeosciences (2023): e2022JG006818.