Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN 47906;
Northern Research Station, Forest Service, US Department of Agriculture, Newtown Square, PA 19073.
Proc Natl Acad Sci U S A. 2019 Aug 27;116(35):17371-17376. doi: 10.1073/pnas.1820601116. Epub 2019 Aug 12.
Worldwide, forests are increasingly affected by nonnative insects and diseases, some of which cause substantial tree mortality. Forests in the United States have been invaded by a particularly large number (>450) of tree-feeding pest species. While information exists about the ecological impacts of certain pests, region-wide assessments of the composite ecosystem impacts of all species are limited. Here we analyze 92,978 forest plots distributed across the conterminous United States to estimate biomass loss associated with elevated mortality rates caused by the 15 most damaging nonnative forest pests. We find that these species combined caused an additional (i.e., above background levels) tree mortality rate of 5.53 TgC per year. Compensation, in the form of increased growth and recruitment of nonhost species, was not detectable when measured across entire invaded ranges but does occur several decades following pest invasions. In addition, 41.1% of the total live forest biomass in the conterminous United States is at risk of future loss from these 15 pests. These results indicate that forest pest invasions, driven primarily by globalization, represent a huge risk to US forests and have significant impacts on carbon dynamics.
全球范围内，森林正日益受到非本地昆虫和疾病的影响，其中一些导致了大量树木死亡。美国的森林受到了大量（>450 种）以树木为食的害虫的侵袭。虽然某些害虫的生态影响信息已经存在，但对所有物种的综合生态系统影响的区域范围评估是有限的。在这里，我们分析了分布在美国大陆的 92978 个森林样地，以估计与 15 种最具破坏性的非本地森林害虫导致的高死亡率相关的生物量损失。我们发现，这些物种加在一起导致每年额外（即高于背景水平）的 5.53TgC 树木死亡率。在整个入侵范围内，以非寄主物种的生长和繁殖增加的形式进行补偿是无法检测到的，但在害虫入侵几十年后确实会发生。此外，美国大陆总活森林生物量的 41.1%面临着未来因这 15 种害虫而损失的风险。这些结果表明，主要由全球化驱动的森林害虫入侵对美国森林构成了巨大威胁，并对碳动态产生了重大影响。
