Canopy cover data from the Ice Storm Experiment (ISE) plots

Large-scale disturbances such as ice storms may increase in frequency and intensity as climate changes. While disturbances are a natural component of forest ecosystems, climatically driven alteration to historical patterns may impart fundamental change to ecosystem function. At Hubbard Brook Experimental Forest, NH, experimental ice storms of varying severity were applied to replicate plots of mature northern hardwoods to quantify their effects on forested ecosystems. We assessed ice storm treatment effects on insectivorous foliage-gleaning birds and their interactions with larval Lepidoptera. These birds are charismatic, of conservation concern, and are a major predator of caterpillars. In turn, lepidopterans are the dominant herbivores in temperate forests and are integral to ecosystem function. We predicted that avian abundance would increase due to additional structural heterogeneity caused by ice treatments, with a concomitant increase in caterpillar predation. Point counts were used to measure insectivorous bird activity in the ice storm experiment plots and additional control plots before and after treatments. Point counts were conducted in June 2015 and June 2016. Icing occurred in January-February 2016. We deployed and retrieved plasticine model caterpillars and estimated predation from characteristic marks to these surrogates. Abundance of foliage-gleaning birds was higher in the ice storm plots and birds responded to treatments as a single diffuse disturbance rather than on an individual plot level. All species except one were observed both before and after the ice treatments. Surprisingly, predation on caterpillar models was unaffected by ice storm treatments but rather was a function of caterpillar density. The increase in avian abundance in the ice storm treatment plots corroborates other studies of bird responses to relatively small-scale disturbances in forests and the limited change in species composition was expected given the plot size. We conclude that ice storms may provide beneficial changes for foliage-gleaning birds in the growing season following the disturbance. These data were gathered as part of the Hubbard Brook Ecosystem Study (HBES). The HBES is a collaborative effort at the Hubbard Brook Experimental Forest, which is operated and maintained by the USDA Forest Service, Northern Research Station. A complete analysis of these data can be found in: Leuenberger, W. M. (2017). Response of larval lepidoptera and their avian predators to experimental ice storms in a northeastern forest (Order No. 10282770). Available from ProQuest Dissertations & Theses A&I. (1950488566).

随着气候变化，冰暴（ice storm）等大规模干扰事件的发生频率与强度或将上升。干扰本是森林生态系统的天然组成部分，但气候变化驱动的历史干扰格局改变，可能会对生态系统功能造成根本性影响。本研究依托美国新罕布什尔州哈伯德布鲁克实验林（Hubbard Brook Experimental Forest），通过对成熟北方硬阔叶林区的重复样地施加不同强度的人工冰暴，量化其对森林生态系统的作用效果。我们评估了冰暴处理对食虫性叶面觅食鸟类（insectivorous foliage-gleaning birds）及其与鳞翅目（Lepidoptera）幼虫间相互作用的影响。这类鸟类兼具公众认知度与保护关注度，是毛虫的主要捕食类群；而鳞翅目幼虫是温带森林中的优势植食类群，对生态系统功能具有核心作用。我们提出研究假设：冰暴处理会通过增加林分结构异质性提升鸟类种群丰度，同时伴随毛虫捕食压力的上升。本研究采用点计数法，于2015年6月与2016年6月对冰暴实验样地及配套对照样地内的食虫鸟类活动进行监测，调查时段覆盖冰暴处理前后。人工冰暴施加于2016年1—2月。我们布设并回收了橡皮泥模拟毛虫模型，通过其表面的特征性咬痕估算捕食压力。数据分析结果显示：冰暴样地内的叶面觅食鸟类丰度更高，且鸟类对该干扰的响应呈现整体弥散性特征，而非单样地特异性响应；除1个物种外，其余所有鸟类物种均在冰暴处理前后被观测到。值得注意的是，毛虫模型的捕食率并未受冰暴处理的显著影响，而是与毛虫种群密度相关。冰暴样地内鸟类丰度的提升，与此前针对森林小规模干扰的鸟类响应研究结果一致；而样地尺度有限，也符合物种组成变化程度有限的预期。我们得出结论：冰暴可能会在干扰发生后的生长季为叶面觅食鸟类带来积极影响。本数据集隶属于哈伯德布鲁克生态系统研究（Hubbard Brook Ecosystem Study, HBES）。HBES是由美国农业部林务局（USDA Forest Service）北部研究站（Northern Research Station）运营维护的哈伯德布鲁克实验林开展的合作研究项目。针对本数据集的完整分析可参见：Leuenberger, W. M. (2017). 美国东北部森林中鳞翅目幼虫及其鸟类捕食者对人工冰暴的响应（学位论文编号：10282770）。可通过ProQuest学位论文与学位论文全文数据库（ProQuest Dissertations & Theses A&I）获取（馆藏编号：1950488566）。