Download or read book Forest Responses to Emerald Ash Borer-induced Ash Mortality written by Wendy S. Klooster and published by . This book was released on 2012 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Invasions by exotic insect pests and pathogens have been devastating North American forests for decades. Presently, emerald ash borer (EAB; Agrilus planipennis) is devastating populations of native ash (Fraxinus species) trees throughout eastern North America. Disturbances, such as canopy gap formation due to EAB-induced ash mortality, alter availability of resources including light, water, and mineral nutrients, potentially resulting in shifts in plant community composition. Following the loss of nearly all reproductively mature trees, ash regeneration was effectively eliminated, and the "orphaned cohort" of ash in the seedling layer represents the potential for persistence of ash in EAB-impacted forests. Hemispherical photographs, used to calculate percent gap fraction, were taken at a height of 1.5 m to determine how loss of ash was affecting radiant energy resources available to the understory vegetation. Variation among gap fraction values indicated high heterogeneity in light reaching the forest understory. Percent gap fraction was negatively correlated with percent plant cover within the 2 - 5 m and> 5 m layers, suggesting that while gaps may have formed in the canopy layer, light was intercepted before reaching the forest understory. Plant abundance and composition within the forest understory did not change dramatically during the course of the study, nor was there a direct connection between species abundance or diversity and gap fraction. Plant communities were slightly differentiated by the soil hydrological conditions, and less diverse communities occurred in mesic and xeric sites than in hydric sites. Growth of invasive and native species in the understory was not influenced by percent gap fraction; invasive species typically outgrew native species regardless of light level and soil hydrological condition. In a comparison of emergence and survival of Lonicera maackii and Rosa multiflora under various native and invasive leaf litters we found no difference in establishment success for either invasive species under the different leaf litters over two or three growing seasons. However, leaf litter from ash and many of the invasive species contained similarly high concentrations of Ca and P, suggesting some degree of functional overlap, which may play an important ecological role if ash species are eliminated from North American forests following EAB-induced mortality and if invasive species increase in abundance. In EAB-infested forests, plant community responses to ash mortality will be based on the hierarchical structure of what plant species are able to grow in the climate, soil conditions, and topography within the impacted sites, as well as the stochastic nature of which species are poised to colonize gaps following canopy tree mortality. As EAB infestation continues to spread throughout North American forests, fewer vegetation patches will include ash as an important component, potentially altering the overall mosaic of habitat and ecosystem function across the landscape. The results of these studies did not conclusively answer the question of how forests will change following EAB-induced ash mortality; however, these data will provide an excellent baseline for future research on long-term impacts of EAB on northern forests.