LTREB: Exotic Pests, Nitrogen Saturation, and Nutrient Cycling in a Northeastern Forest

这个LTREB项目将支持对威胁美国东部森林的两种外来害虫——舞毒蛾和铁杉蛾的直接和间接影响的持续研究。舞毒蛾是东部森林最重要的掠叶动物。它优先攻击橡树为主的森林，并在周期性爆发期间造成广泛的落叶。铁杉绵蚜是最近引进的一种害虫，它对大西洋中部各州和新英格兰的铁杉树造成了毁灭性的破坏。它是一种类似蚜虫的昆虫，专门以铁杉为食，通常会导致树木在感染后的几年内死亡率达到100%。这里的研究问题涉及到这些害虫对森林氮循环的影响。这两种害虫发生的背景是，由于化石燃料燃烧产生的氮氧化物排放和农业活动产生的氨排放，氮沉积水平升高。氮沉降和这些害虫对所研究的森林生态系统氮循环的影响之间很可能存在复杂的相互作用。这个LTREB项目将继续在纽约州米尔布鲁克的长期研究地块上测量森林生产力和养分循环。这些地块包括可能受到舞毒蛾影响的地区的橡树地块，以及即将受到铁杉羊毛蚜侵扰的地区的铁杉地块。此外，还将在橡树林中进行长期加氮试验。这项工作与东部森林的管理直接相关，因为舞毒蛾和铁杉绵蚜是该地区最具破坏性的两种害虫。氮饱和现象及其对森林健康和地表水质量的影响，是美国东部一个新兴的管理和政策问题。因此，研究这两种应力的相互作用具有重要的科学意义和实际意义。

Lovett0129138This LTREB project will support sustained research on the direct and indirect effects of two exotic pests that threaten the forests of the eastern US, the gypsy moth and the hemlock wooly adelgid. The gypsy moth is the most important defoliator of eastern forests. It preferentially attacks oak-dominated forests and causes widespread defoliation during periodic outbreaks. The hemlock woolly adelgid is a more recently introduced pest that is devastating hemlock trees in the mid-Atlantic states and New England. It is an aphid-like insect that feeds exclusively on hemlocks, and generally results in 100% mortality of trees within several years after infestation. The research questions here involve the effect of these pests on the nitrogen cycle of forests. Both of these pests are occurring against the backdrop of elevated levels of nitrogen deposition due to nitrogen oxide emissions from fossil fuel combustion and ammonia emission from agricultural activities. These is a strong probability of a complex interaction between nitrogen deposition and the effects of these pests on the nitrogen cycles of the forest ecosystems under study. This LTREB project will continue measurements of forest productivity and nutrient cycling in long-term study plots in Millbrook, NY. The plots include both oak plots in the zone likely to be affected by the gypsy moth, and hemlock plots in an area soon to be infested with hemlock woolly adelgid. In addition, a long-term N-addition experiment in an oak forest will be maintained, as well. This work has direct relevance to management of eastern forests, in that gypsy moth and hemlock woolly adelgid are two of the most devastating pests in the region. The phenomenon of nitrogen saturation and its effects on forest health and the quality of surface waters, is an emerging management and policy issue in the eastern US. Thus, the study of the interaction of these two stresses is of both scientific and practical importance.