Chapter 42
Spruce Budworm Dynamics
Books are subject among other Chances to fire, and the Worme.
(Whitlock Zootomia, 1654)
42.1 Spruce Budworm Model
A classical example for the implications of catastrophes for ecosystem management
is the spruce budworm dynamics. Spruce budworm is a caterpillar that feeds on
spruce and fir forests in the northeastern United States and eastern Canada. For
many years, population sizes of spruce budworm are low and have little impact on
trees. When forest stands reach maturity, however, spruce budworm populations
explode, seriously affecting the forest by defoliating the trees. As a result of
defoliation, trees are weakened and ultimately may die. With the death of trees
comes a loss of the food source for spruce budworm and a consequent population
crash.
The cycle of low spruce budworm population densities, followed by population
explosions and catastrophic collapse tend to repeat themselves over the course of
years. The resulting damage and death of trees affects negatively the timber and
paper pulp industries of the region. Frequently, forest managers decided to spray
forest stands to control budworm populations. The dynamics inherent in the system,
however, lead it to follow its own path, making ever more extensive pest control
necessary. If those controls fail, outbreaks are more sever and devastating than if
the system had been left to control itself, as recent experiences in the US and
Canada show.
A save-disabled version of STELLA and the computer models of this book are available at
www.iseesystems.com/modelingdynamicbiologicalsystems.
B. Hannon and M. Ruth, Modeling Dynamic Biological Systems,
Modeling Dynamic Systems, DOI 10.1007/978-3-319-05615-9_42,
© Springer International Publishing Switzerland 2014
381
Spruce Budworm Dynamics
Books are subject among other Chances to fire, and the Worme.
(Whitlock Zootomia, 1654)
42.1 Spruce Budworm Model
A classical example for the implications of catastrophes for ecosystem management
is the spruce budworm dynamics. Spruce budworm is a caterpillar that feeds on
spruce and fir forests in the northeastern United States and eastern Canada. For
many years, population sizes of spruce budworm are low and have little impact on
trees. When forest stands reach maturity, however, spruce budworm populations
explode, seriously affecting the forest by defoliating the trees. As a result of
defoliation, trees are weakened and ultimately may die. With the death of trees
comes a loss of the food source for spruce budworm and a consequent population
crash.
The cycle of low spruce budworm population densities, followed by population
explosions and catastrophic collapse tend to repeat themselves over the course of
years. The resulting damage and death of trees affects negatively the timber and
paper pulp industries of the region. Frequently, forest managers decided to spray
forest stands to control budworm populations. The dynamics inherent in the system,
however, lead it to follow its own path, making ever more extensive pest control
necessary. If those controls fail, outbreaks are more sever and devastating than if
the system had been left to control itself, as recent experiences in the US and
Canada show.
A save-disabled version of STELLA and the computer models of this book are available at
www.iseesystems.com/modelingdynamicbiologicalsystems.
B. Hannon and M. Ruth, Modeling Dynamic Biological Systems,
Modeling Dynamic Systems, DOI 10.1007/978-3-319-05615-9_42,
© Springer International Publishing Switzerland 2014
381