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Interactions of Emerging Threats and Bark Beetle-Microbial Dynamics in Forest Ecosystems (From W1187)
L.K. Rieske-Kinney, F. Stephen, W. Jacobi, L. Bernier, P. Bonello, D. Shaw
Department of Entomology
A changing set of factors is influencing forests at a scale that some argue is unprecedented in the modern era. Much of the US has experienced catastrophic weather for the past 10 years. Changing climate has altered temperature regimes. Invasive exotic species have altered species composition of landscapes. These are just a few of the factors altering forest susceptibility to insects and pathogens.These effects cascade, as, for example, insects and pathogens alter fire regimes, and with increased temperature and drought, facilitate an increase in the number, size and severity of forest fires.
Changes in land use patterns are intensifying interactions at the forest - human interface, which imposes societal goals on natural ecosystems. Among the demands citizens expect from forested ecosystems are resistance to fire, carbon sequestration, clean water and aesthetic quality.
Society increasingly demands ecosystem services at a time when these ecosystems are changing rapidly. For example, hardwoods are recently becoming important to land managers and the public. In the Intermountain West, land managers have become aware that aspen is a critical species and may be declining. We have little research to guide us in restoration efforts. Sudden oak death is changing the composition of West Coast forests. In Midwestern states, the exotic Emerald Ash borer threatens both urban and wild ash.
Understanding dynamics of insect, pathogen and associated microbes in forests is critical to maintaining the ecosystem services forests provide. Funding for both basic and applied research has declined. We must work collectively to address the problems facing forests today, and to train future professionals so that society does not lose the capacity to respond to new or changing environmental crises.
Our research on interactions among insects and fungi and their diversity is providing conceptual and practical models of how invasive insects and fungi can work to degrade forests. Changing large scale factors are altering forests in ways that we could not predict. Without continued and integrated study of forests, these negative impacts will become the norm and they will deprive society of the ecosystem services that forests provide. Our efforts to characterize insect, fungus and host tree interactions have already provided benefits. We know that some fungi are detrimental to bark beetles, some are beneficial, and some can be either depending on context. Efforts are underway to use fungal population structures as 1) indicators of trends in bark beetle outbreaks; and 2) to manage bark beetle populations.
We understand some system specific dynamics and comparison approaches at individual and local scales, but not at cross scale interactions needed to address today's rapidly changing landscape. We have the tools to address many of the questions; we need a collaborative, multistate, and even an international approach to understand feedbacks among insects, microbial associates, the forests that host them, and the agents of change driving this complex system.
2010 Project Description
Non-native invasive species are gaining a foothold in forests of the US and Kentucky, and we are working to gain a greater understanding of their impacts on forest composition and forest structure. We established and surveyed 126 vegetation plots across fourteen counties to establish baseline conditions. After assessing current forest conditions, we are modeling the effects of invasion by specific exotic organisms on vegetation and structure in specific forest types. Based on current forest conditions and specific exotic invaders' impacts, we can project forest growth 50 years into the future. Thus far we have focused on the hemlock woolly adelgid, the emerald ash borer, and the sudden oak death pathogen. Thousand cankers and laurel wilt diseases are pending.
Exotic species will undoubtedly influence future vegetation and alter the ecological interactions within a forest community. Our results have implications with respect to determining the level of proactive management needed to minimize our losses and to develop ways of mitigating the ecological and economic impacts of invasive species. Forest modeling predicts subsequent decline in the hemlock forest type due to hemlock woolly adelgid, and a considerable shift in oak composition due to the sudden oak death pathogen. This work will help land managers determine viable options for managing future forests.
Spaulding, H.L. and L.K. Rieske. 2010. A glimpse at future forests: predicting the effects of Phytophthora ramorum on high-risk forests of southern Appalachia. Biological Invasions, In press.
Spaulding, H.L. and L.K. Rieske. 2010. The aftermath of an invasion: Structure and composition of Central Appalachian hemlock forests following establishment of the hemlock woolly adelgid, Adelges tsugae. Biological Invasions. DOI: 10.1007/s10530-010-9704-0.
Coleman, T.W., A. Martin, J.R. Meeker, S. Clarke, and L.K. Rieske. 2010. Sixteen years of vegetation succession in loblolly pine forests following catastrophic stand replacement. USDA Forest Service General Technical Report SRS-129.
Coleman, T.W., J.R. Meeker, S.R. Clarke, and L.K. Rieske. 2008. Forest composition following overstory mortality from southern pine beetle and associated treatments. Canadian Journal of Forest Research 38, 1-13.
Coleman, T.W., J.R. Meeker, S.R. Clarke, and L.K. Rieske. 2008. The suppression of Dendroctonus frontalis and subsequent wildfire have an impact on forest stand dynamics. Applied Vegetation Science 11, 231-242