Host size and distance to infested stands predicts defoliation of aspen by non-native white satin moth
Loading...
Authors
Lewis, Justin Scott
Issue Date
2023
Type
Thesis
Language
Keywords
Forest Ecology , Forest Pests & Pathogens , Invasive Species , Leucoma salicis , Populus tremuloides , Sierra Nevada
Alternative Title
Abstract
Forest decline and tree mortality events often result from simultaneous stressors and can be amplified by novel climatic conditions and the introduction of invasive pests and pathogens. The potential compounding effects of these novel disturbances pose a risk of cascading impacts if they affect species with outsized ecological influence, such as foundation species like quaking aspen (Populus tremuloides Michx.). Quaking aspen is limited in extent in the Sierra Nevada and Sierra Front forests, making the relatively recent introduction of the invasive aspen defoliator, white satin moth (Leucoma salicis), especially concerning. To understand current aspen stand conditions and the extent of white satin moth in the region, we assessed the impacts of a multi-year satin moth defoliation event on quaking aspen stand composition and dynamics. A conditional random forest model was used to narrow predictor variables prior to evaluating drivers of defoliation and aspen regeneration with generalized linear models. We found that defoliation rates were strongly influenced by the availability of aspen host trees and the distance to the nearest stand infested by white satin moth, while aspen regeneration was most strongly influenced by heat load index as warmer soil temperatures are more likely to promote aspen root sucker initiation. White satin moth may lead to declines in regional aspen stands yet may concurrently promote regeneration through more favorable establishment conditions. Our findings indicate that the occurrence of white satin moth is likely to spread throughout the Carson Range, but further monitoring is necessary to better understand its impacts on aspen stand composition, particularly regeneration and potential declines.