COS 93-1 - CANCELLED - Interactions between defoliating insects and climate change alter forecasts of forest change

Tuesday, August 16, 2022

1:30 PM – 1:45 PM EDT

Location: 516A

Presenting Author(s)

HS

Hiromitsu Sato

Ontario Ministry of Northern Development, Mining, Natural Resources, and Forestry, Canada

Coauthor(s)

SM

Stephen J. Mayor

Research Scientist
Ontario Ministry of Northern Development, Mines, Natural Resources and Forestry
Sault Ste. Marie, Ontario, Canada
JC

Jean-Noel Candau

Natural Resources Canada - Canadian Forest Service, Canada
MG

Martin Girardin

Natural Resources Canada - Canadian Forest Service, Canada
JK

Jed Kaplan

University of Hong Kong, Hong Kong
eC

emeline Chaste

AgroParisTech, France

Background/Question/Methods

Eastern Spruce Budworm (ESBW) is a primary biotic disturbance agent in the boreal forests of Eastern Canada, with implications for the forestry industry, carbon dynamics, and avian community ecology. ESBW defoliates its preferred hosts-- balsam fir and spruce species--over multiple years, ultimately leading to mortality. Outbreaks occur cyclically, roughly every 30 years,and can increase risk and severity of wildfire. Despite the ecological and economic impacts of defoliators such as ESBW, there has been little effort in building representation in important process-based Earth System models. Moreover, patterns of ESBW outbreak will likely shift geographically due to climate change, adding to uncertainties in ecosystem projections. We used a Dynamic Global Vegetation Model (DGVM), LPJ-LMfire, to simulate the large-scale spatiotemporal dynamics of forests in response to climate change. We integrate for the first time ESBW defoliation into this DGVM, allowing more realistic forecasts based on both abiotic and biotic disturbances and their interactions.

Results/Conclusions

We found that bottom up control of ESBW, driven by climate and forest growth, was sufficient to explain both cyclical outbreak patterns and general spatial distributions of ESBW. The exclusion of parasitism or predation, while a simplification, demonstrates the promise and utility of incorporating biotic disturbance into process based DGVMs. We performed a factorial experiment to investigate the interactions of ESBW with wildfire. ESBW outbreaks increased burned area by up to 20 percent relative to control, mainly due to increased fuel loads.Interaction strengths between ESBW and fire were higher in the drier Western region of the boreal forest. We forecast major changes in the distributions of forest types in the eastern boreal region, particularly at the southern boreal margins, that are facilitated by these disturbance interactions. We identify regions where forest managers may expect reduced boreal resilience due to climate change, and the alternative vegetation types that are likely to penetrate.