Invasive species are an exponentially expanding threat to wildland ecosystems throughout the western United States. Invasive species are those species that are nonnative to the invaded ecosystem, and whose introduction is likely to result in economic or environmental harm, or reduce ecosystem integrity. In Center investigations, we include native outbreaks of plants, pathogens, and insects within their natural range that have reached deleterious, uncharacteristic levels (‘exceptional outbreaks’).
Human activities are the primary agent for invasive species spread. Continued transport of insects (often carried on shipping pallets or firewood), plant invasives, and diseases (often carried by agricultural or horticultural plants and insects) to US ports, as well as state-to-state transfers, increase the number of introductions every year. The ability to quickly identify and pinpoint the source of harmful introductions is critical for developing effective responses. Understanding genetic similarities, and functional type responses to current and future environmental conditions can help us anticipate and potentially prevent new introductions. Developing genetic libraries and tracking the geographic origin of emerging invasive threats has been an important focus of WWETAC-funded projects.
Since the early 2000’s, bark beetle outbreaks have contributed to the largest biotic disturbance in recorded history. Exceptional outbreaks of insects and diseases are increasingly common and occur due to climate change and increases in (1) summer temperature, increasing season length and the number of potential generations per year, (2) increasing winter minimum temperatures, reducing over winter mortality, and (3) host susceptibility due to severe drought stress, altering production and quality of resin. WWETAC-funded projects on invasives focuses on understanding the mechanisms of insect outbreak, pine susceptibility and defenses, supporting the development of predictive models, and using remote sensing tools to detect susceptible tree-at-risk in the landscape to anticipate locations of exceptional outbreaks.
Links to highlighted studies (next update June 2018):
Distribution of Armillaria (Root rot) under future climate scenarios.
Effects of bark beetle mortality on wildfire behavior.
Risk of Canada Thistle establishment due to forestry activities.