With reference to massive outbreaks of a variety of bark beetles occurring across the forests of western North America, it is stressed that an accurate assessment of the extent of the problem is the first step toward formulating effective adaptive management strategies. This assessment will only be possible through a coordinated effort that combines all available technologies, that is an approach that builds on satellite image analysis, aerial survey from fixed-wing aircraft, and on the ground observation and measurement.
Land managers often are responsible for the maintenance of species diversity and resilience. This requires knowledge of ecosystem dynamics over decades and centuries. Resource-driven (bottom-up) models have guided early thought on managing species and ecosystems. Under this paradigm, carnivores have little ecological value, and throughout the 20 th Century carnivore management strategies (often extirpation) have reflected that concept. An alternative hypothesis, however, states that herbivores reduce the biomass of plants, but in turn, the biomass of herbivores is checked by the presence of carnivores. As such, carnivores have great ecological value. Their predation activities create impacts that ripple downward through the trophic levels of an ecosystem. Here we discuss some potential pathways through which carnivores contribute to ecosystem processes and species diversity. The subtleties of these interactions have strong implications for management strategies of carnivores. Without considering these indirect impacts, short-sighted management strategies to reduce carnivores might cause extensive and long-term changes in ecosystem structure and function.
Journal Article The Yellowstone Experience: The use of science, with humility, in public policy Get access Louisa Willcox Louisa Willcox Search for other works by this author on: Oxford Academic Google Scholar BioScience, Volume 45, Issue Supplement_1, 1995, Pages S-79–S-83, https://doi.org/10.2307/1312449 Published: 01 January 1995
Widespread outbreaks of mountain pine beetles (MPB) are occurring throughout the range of this native insect. Episodic outbreaks are a common occurrence in the beetles' primary host, lodgepole pine. Current outbreaks, however, are occurring in habitats where outbreaks either did not previously occur or were limited in scale. Herein, we address widespread, ongoing outbreaks in high‐elevation, whitebark pine forests of the Greater Yellowstone Ecosystem, where, due to an inhospitable climate, past outbreaks were infrequent and short lived. We address the basic question: are these outbreaks truly unprecedented and a threat to ecosystem continuity? In order to evaluate this question we (1) present evidence that the current outbreak is outside the historic range of variability; (2) examine system resiliency to MPB disturbance based on adaptation to disturbance and host defenses to MPB attack; and (3) investigate the potential domain of attraction to large‐scale MPB disturbance based on thermal developmental thresholds, spatial structure of forest types, and the confounding influence of an introduced pathogen. We conclude that the loss of dominant whitebark pine forests, and the ecological services they provide, is likely under continuing climate warming and that new research and strategies are needed to respond to the crisis facing whitebark pine.
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