Abstract:
Drought has promoted large-scale, insect-induced tree mortality in
recent years, with severe consequences for ecosystem function,
atmospheric processes, sustainable resources and global biogeochemical
cycles. However, the physiological linkages among
drought, tree defences, and insect outbreaks are still uncertain,
hindering our ability to accurately predict tree mortality under ongoing
climate change. Herewepropose an interdisciplinary research
agenda for addressing these crucial knowledge gaps. Our framework
includes field manipulations, laboratory experiments, and
modelling of insect and vegetation dynamics, and focuses on how
drought affects interactions between conifer trees and bark beetles.
We build upon existing theory and examine several key assumptions:
(1) there is a trade-off in tree carbon investment between
primary and secondary metabolites (e.g. growth vs defence); (2)
secondary metabolites are one of the main component of tree
defence against bark beetles and associated microbes; and (3)
implementing conifer-bark beetle interactions in current models
improves predictions of forest disturbance in a changing climate.
Our framework provides guidance for addressing a major shortcoming
in current implementations of large-scale vegetation
models, the under-representation of insect-induced tree mortality.
