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USGS · 70027694

Regional vegetation die-off in response to global-change-type drought

D.D. Breshears·N.S. Cobb·P.M. Rich·K. P. Price·Craig D. Allen·R.G. Balice·W.H. Romme·J.H. Kastens·M. Lisa Floyd·J. Belnap·J. J. Anderson·O.B. Myers·Clifton W. Meyer
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Abstract

Future drought is projected to occur under warmer temperature conditions as climate change progresses, referred to here as global-change-type drought, yet quantitative assessments of the triggers and potential extent of drought-induced vegetation die-off remain pivotal uncertainties in assessing climate-change impacts. Of particular concern is regional-scale mortality of overstory trees, which rapidly alters ecosystem type, associated ecosystem properties, and land surface conditions for decades. Here, we quantify regional-scale vegetation die-off across southwestern North American woodlands in 2002-2003 in response to drought and associated bark beetle infestations. At an intensively studied site within the region, we quantified that after 15 months of depleted soil water content, >90% of the dominant, overstory tree species ( Pinus edulis , a piñon) died. The die-off was reflected in changes in a remotely sensed index of vegetation greenness (Normalized Difference Vegetation Index), not only at the intensively studied site but also across the region, extending over 12,000 km 2 or more; aerial and field surveys confirmed the general extent of the die-off. Notably, the recent drought was warmer than the previous subcontinental drought of the 1950s. The limited, available observations suggest that die-off from the recent drought was more extensive than that from the previous drought, extending into wetter sites within the tree species' distribution. Our results quantify a trigger leading to rapid, drought-induced die-off of overstory woody plants at subcontinental scale and highlight the potential for such die-off to be more severe and extensive for future global-change-type drought under warmer conditions.

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D.D. Breshears, N.S. Cobb, P.M. Rich, K. P. Price, Craig D. Allen, R.G. Balice, W.H. Romme, J.H. Kastens, M. Lisa Floyd, J. Belnap, J. J. Anderson, O.B. Myers, Clifton W. Meyer. 2005-10-10. Regional vegetation die-off in response to global-change-type drought. https://doi.org/10.1073/pnas.0505734102

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