Responses of insect pests, pathogens, and invasive plant species to climate change in the forests of northeastern North America: What can we predict?1

Climate models project that by 2100, the northeastern US and eastern Canada will warm by approximately 3– 5 8C, with increased winter precipitation. These changes will affect trees directly and also indirectly through effects on ‘‘nuisance’’ species, such as insect pests, pathogens, and invasive plants. We review how basic ecological principles can be used to predict nuisance species’ responses to climate change and how this is likely to impact northeastern forests. We then examine in detail the potential responses of two pest species (hemlock woolly adelgid (Adelges tsugae Annand) and forest tent caterpillar (Malacosoma disstria Hubner)), two pathogens (armillaria root rot (Armillaria spp.) and beech bark disease (Cryptococcus fagisuga Lind. + Neonectria spp.)), and two invasive plant species (glossy buckthorn (Frangula alnus Mill.) and oriental bittersweet (Celastrus orbiculatus Thunb.)). Several of these species are likely to have stronger or more widespread effects on forest composition and structure under the projected climate. However, uncertainty pervades our predictions because we lack adequate data on the species and because some species depend on complex, incompletely understood, unstable relationships. While targeted research will increase our confidence in making predictions, some unReceived 25 January 2008. Accepted 1 October 2008. Published on the NRC Research Press Web site at cjfr.nrc.ca on 30 January 2009. J.S. Dukes2,3,4 and K.A. Theoharides.7 University of Massachusetts, Department of Biology, Boston, MA 02125, USA. J. Pontius.5,3 USDA Forest Service, Northern Research Station, 271 Mast Road, Durham, NH 03824, USA. D. Orwig and K. Stinson. Harvard University, Harvard Forest, Petersham, MA 01366, USA. J.R. Garnas, E.E. Stange, and M. Ayres. Dartmouth College, Biological Sciences, Gilman Hall, Hanover, NH 03755, USA. V.L. Rodgers.6 Boston University, Biology Department, 5 Cummington Street, Boston, MA 02215, USA. N. Brazee. University of Massachusetts, Department of Plant, Soil, and Insect Sciences, 270 Stockbridge Road, Amherst, MA 010039320, USA. B. Cooke. Canadian Forest Service, Northern Forestry Centre, 5320 122 Street, Edmonton, AB T6H 3S5, Canada. R. Harrington. University of Massachusetts, Natural Resource Conservation, 318 Holdsworth, Amherst, MA 01003, USA. J. Ehrenfeld. Cook College, Rutgers University, Department of Ecology, Evolution, and Natural Resources, 14 College Farm Road, New Brunswick, NJ 08901, USA. J. Gurevitch. State University of New York, Department of Ecology and Evolution, Life Science Building, Stony Brook, NY 117945245, USA. M. Lerdau. University of Virginia, Department of Environmental Sciences and Department of Biology, Clark Hall, 291 McCormick Road, Charlottesville, VA 22904-4123, USA. R. Wick. University of Massachusetts, Department of Microbiology, 203 Morrill Science Center IVN, 639 North Pleasant Street, Amherst, MA 01003-9320, USA. 1This article is one of a selection of papers from NE Forests 2100: A Synthesis of Climate Change Impacts on Forests of the Northeastern US and Eastern Canada. 2Corresponding author (e-mail: [email protected]). 3Authors contributed equally to this work. 4Present address: Department of Forestry and Natural Resources and Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA. 5Present address: Rubenstein School of Environment and Natural Resources, 342 Aiken Center, University of Vermont, Burlington, VT 05405, USA. 6Present address: Babson College, Math and Science Division, Babson Park, MA 02457, USA. 7Present address: Defenders of Wildlife, 1130 17th Street, NW Washington, DC 20036, USA. 231 Can. J. For. Res. 39: 231–248 (2009) doi:10.1139/X08-171 Published by NRC Research Press certainty will always persist. Therefore, we encourage policies that allow for this uncertainty by considering a wide range of possible scenarios. Résumé : Les modèles climatiques prévoient des températures 3–5 8C plus élevées et des précipitations hivernales plus abondantes vers 2100 dans le nord-est des États-Unis et l’est du Canada. Ces changements affecteront les arbres directement et indirectement via leurs effets sur des espèces nuisibles telles que les insectes ravageurs, les agents pathogènes et les plantes invasives. Nous passons en revue la façon dont les principes écologiques peuvent être utilisés pour prédire la réaction des espèces nuisibles aux changements climatiques et la façon dont cela pourrait affecter les forêts du nord-est. Nous étudions ensuite en détail les réactions potentielles de deux insectes ravageurs : le puceron lanigère de la pruche (Adelges tsugae Annand) et la livrée des forêts (Malacosoma disstria Hubner), deux agents pathogènes : le pourridié agaric (Armillaria spp.) et la maladie corticale du hêtre (Cryptococcus fagisuga Lind. + Neonectria spp.) et deux espèces de plantes invasives : le nerprun bourdaine (Frangula alnus Mill.) et la célastre asiatique (Celastrus orbiculatus Thunb.). Plusieurs de ces espèces auront probablement des effets plus prononcés ou plus étendus sur la composition et la structure de la forêt dans les conditions climatiques anticipées. Cependant, nos prédictions demeurent incertaines à cause du manque de données adéquates sur ces espèces et parce que certaines espèces dépendent de relations complexes, peu connues et instables. La recherche orientée nous permettra de faire des prédictions avec une plus grande confiance, mais il restera toujours une certaine incertitude. Par conséquent, nous encourageons les politiques qui tiennent compte de cette incertitude en considérant une vaste gamme de scénarios potentiels. [Traduit par la Rédaction] ______________________________________________________________________________________