Effects of introduced insects and diseases on forest ecosystems in the Catskill Mountains of New York.

Repeated invasions of non-native insects and pathogens have altered the structure and function of forest ecosystems in the Catskill Mountains of New York State, and will continue to do so in the future. Gypsy moth, beech bark disease, and hemlock woolly adelgid are among the insects and diseases currently established in the Catskills that are having significant effects on forests. Many others, including emerald ash borer, Asian long-horned beetle, Phytophthora ramorum, and Sirex wood wasp, are either very recently established in the Catskills or have been found elsewhere in North America and threaten to spread to this region. Short-term disturbances associated with these pests include reduction of productivity, tree decline and mortality, disruption of nutrient cycles, and reduction of seed production. Longer-term impacts are associated with shifts in tree species composition that alter productivity, nutrient cycling, and biodiversity. Catskill forests at mid to high elevations, such as the New York State Forest Preserve lands, are dominated by sugar maple and are particularly vulnerable to pests that use maple as a host, including the Asian long-horned beetle. The simultaneous effects of multiple invading insects and pathogens, and their interactions with changing climate and air pollution regimes, make it very difficult to predict the future composition of Catskill forests.