Lemoine Nathan P, Burkepile Deron E, Parker John D
Department of Biology, Colorado State University , Fort Collins , CO , United States.
Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara , CA , United States.
PeerJ. 2017 Mar 21;5:e3102. doi: 10.7717/peerj.3102. eCollection 2017.
Insect herbivores help maintain forest diversity through selective predation on seedlings of vulnerable tree species. Although the role of natural enemies has been well-studied in tropical systems, relatively few studies have experimentally manipulated insect abundance in temperate forests and tracked impacts over multiple years. We conducted a three-year experiment (2012-2014) deterring insect herbivores from seedlings in new treefall gaps in deciduous hardwood forests in Maryland. During this study, we tracked recruitment of all tree seedlings, as well as survivorship and growth of 889 individual seedlings from five tree species: , , spp., , and . Insect herbivores had little effect on recruitment of any tree species, although there was a weak indication that recruitment of was higher in the presence of herbivores. Insect herbivores reduced survivorship of , but had no significant effects on , spp., , or . Additionally, insects reduced growth rates of early pioneer species , , and , but had little effect on more shade-tolerant species and spp. Overall, by negatively impacting growth and survivorship of early pioneer species, forest insects may play an important but relatively cryptic role in forest gap dynamics, with potentially interesting impacts on the overall maintenance of diversity.
食草昆虫通过对易受侵害的树种幼苗进行选择性捕食，有助于维持森林多样性。虽然天敌在热带生态系统中的作用已得到充分研究，但相对较少的研究通过实验控制温带森林中昆虫的数量，并追踪多年的影响。我们在马里兰州落叶阔叶林新形成的树木倒落间隙中进行了一项为期三年（2012 - 2014年）的实验，阻止昆虫食草动物侵害幼苗。在这项研究中，我们追踪了所有树种幼苗的补充情况，以及来自五个树种（分别为、、栎属树种、、）的889株个体幼苗的存活率和生长情况。食草昆虫对任何树种的幼苗补充影响不大，不过有微弱迹象表明，在有食草动物存在的情况下，的幼苗补充率更高。食草昆虫降低了的存活率，但对、栎属树种、、或没有显著影响。此外，昆虫降低了早期先锋树种、和的生长速率，但对更耐荫的树种和栎属树种影响较小。总体而言，森林昆虫通过对早期先锋树种的生长和存活产生负面影响，可能在森林间隙动态中发挥重要但相对隐蔽的作用，对多样性的整体维持可能产生有趣的影响。
