Forest Insect Defoliation and Carbon Dynamics: Simulating Multiple Defoliator Species in Shared Landscapes With Landis-II
Event Website
http://www.nafew2009.org/
Start Date
6-23-2009 8:00 AM
End Date
6-23-2009 8:20 AM
Description
Defoliation outbreaks are dynamic forest disturbances with unique spatial and temporal characteristics that produce distinct changes in forest composition and carbon balance. We simulated defoliation outbreaks using a new module for the forest disturbance and succession model, Landis-II, to better understand the long-term consequences of defoliation on forest carbon. This new module recreates the spatial dynamics of defoliation outbreaks by stochastically drawing parameters that describe spatial pattern from empirical distributions derived from Landsat defoliation maps. The module also captures species specific growth and mortality responses to accumulated defoliation stress. We demonstrate how these simulated defoliation events mimic spatial and temporal patterns of gypsy moth (GM, Lymantria dispar L.) defoliation outbreaks and their effects in the central Appalachian mountains of western Maryland, U.S.A. We simulated aboveground carbon dynamics over 400 years with and without GM defoliation in this mixed deciduous landscape. These simulations facilitated estimation of (1) the impacts of a generalist defoliator on long-term changes in forest composition and carbon storage, and (2) comparison of aboveground carbon dynamics expected in the absence of GM with those following introduction. Simulations were also run with forest tent caterpillar (Malacosoma disstria Hbn.) defoliation, individually and with GM, to examine how multiple defoliators with shared hosts alter long-term aboveground carbon dynamics. Preliminary results show that the introduction of GM disturbance changes the trajectory of forest species composition, facilitating increases in non-host species that would not otherwise occur. Forest carbon storage is temporarily reduced following individual outbreaks, as are long-term means, once GM enters the landscape. Changes in forest carbon storage are even more pronounced when a native defoliator has periodic outbreaks in the same landscape. The results directly illustrate how temperate forest carbon cycles, particularly aboveground carbon pools, are affected by interacting insect disturbances that are a fundamental, but changing part of forest ecosystems.
Forest Insect Defoliation and Carbon Dynamics: Simulating Multiple Defoliator Species in Shared Landscapes With Landis-II
Defoliation outbreaks are dynamic forest disturbances with unique spatial and temporal characteristics that produce distinct changes in forest composition and carbon balance. We simulated defoliation outbreaks using a new module for the forest disturbance and succession model, Landis-II, to better understand the long-term consequences of defoliation on forest carbon. This new module recreates the spatial dynamics of defoliation outbreaks by stochastically drawing parameters that describe spatial pattern from empirical distributions derived from Landsat defoliation maps. The module also captures species specific growth and mortality responses to accumulated defoliation stress. We demonstrate how these simulated defoliation events mimic spatial and temporal patterns of gypsy moth (GM, Lymantria dispar L.) defoliation outbreaks and their effects in the central Appalachian mountains of western Maryland, U.S.A. We simulated aboveground carbon dynamics over 400 years with and without GM defoliation in this mixed deciduous landscape. These simulations facilitated estimation of (1) the impacts of a generalist defoliator on long-term changes in forest composition and carbon storage, and (2) comparison of aboveground carbon dynamics expected in the absence of GM with those following introduction. Simulations were also run with forest tent caterpillar (Malacosoma disstria Hbn.) defoliation, individually and with GM, to examine how multiple defoliators with shared hosts alter long-term aboveground carbon dynamics. Preliminary results show that the introduction of GM disturbance changes the trajectory of forest species composition, facilitating increases in non-host species that would not otherwise occur. Forest carbon storage is temporarily reduced following individual outbreaks, as are long-term means, once GM enters the landscape. Changes in forest carbon storage are even more pronounced when a native defoliator has periodic outbreaks in the same landscape. The results directly illustrate how temperate forest carbon cycles, particularly aboveground carbon pools, are affected by interacting insect disturbances that are a fundamental, but changing part of forest ecosystems.
https://digitalcommons.usu.edu/nafecology/sessions/disturbance/7