Cross-scale interaction of host tree size and climatic water deficit governs bark beetle-induced tree mortality
Cross-scale interaction of host tree size and climatic water deficit governs bark beetle-induced tree mortality

This is a Preprint and has not been peer reviewed. The published version of this Preprint is available: https://doi.org/10.1038/s41467-020-20455-y. This is version 9 of this Preprint.

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Authors

Michael J Koontz, Andrew M. Latimer, Leif A. Mortenson, Christopher J. Fettig, Malcolm P. North

Abstract

The recent Californian hot drought (2012-2016) precipitated unprecedented ponderosa pine (Pinus ponderosa) mortality, largely attributable to the western pine beetle (Dendroctonus brevicomis; WPB). Broad-scale climate conditions can directly shape tree mortality patterns, but mortality rates respond non-linearly to climate when local-scale forest characteristics influence the behavior of tree-killing bark beetles (e.g., WPB). To test for these cross-scale interactions, we conduct aerial drone surveys at 32 sites along a gradient of climatic water deficit (CWD) spanning 350 km of latitude and 1000 m of elevation in WPB-impacted Sierra Nevada forests. We map, measure, and classify over 450,000 trees within 9 km2, validating measurements with coincident field plots. We find greater size, proportion, and density of ponderosa pine (the WPB host) increase host mortality rates, as does greater CWD. Critically, we find a CWD/host size interaction such that larger trees amplify host mortality rates in hot/dry sites. Management strategies for climate change adaptation should consider how bark beetle disturbances can depend on cross-scale interactions, which challenge our ability to predict and understand patterns of tree mortality.

DOI

https://doi.org/10.32942/osf.io/jz964

Subjects

Ecology and Evolutionary Biology, Life Sciences, Terrestrial and Aquatic Ecology

Keywords

climate change-type drought, Dendroctonus brevicomis, disturbance, drones, drought, forest, forest structure, macroecology, Pinus ponderosa, Sierra Nevada, structure from motion

Dates

Published: 2019-12-12 16:10

Last Updated: 2021-01-07 07:48

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License

CC-By Attribution-ShareAlike 4.0 International

Additional Metadata

Data and Code Availability Statement:
All data will be made available via the Open Science Framework upon completion of peer review.