Plasticine caterpillar predation 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.

随着气候变化，冰暴等大规模自然干扰的发生频率与强度或呈上升趋势。尽管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模式改变，或对生态系统功能造成根本性影响。
在美国新罕布什尔州哈伯布鲁克实验林（Hubbard Brook Experimental Forest）中，研究人员对成熟北方硬阔林的重复样地施加不同强度的人工冰暴，以量化其对森林生态系统的影响。本研究评估了冰暴处理对食虫性树叶觅食鸟类及其与鳞翅目（Lepidoptera）幼虫的相互作用的影响。这类鸟类兼具公众关注度与保护价值，是毛虫的主要捕食者；而鳞翅目昆虫则是温带森林中的优势植食类群，对生态系统功能至关重要。本研究推测，冰暴处理带来的群落结构异质性提升将使鸟类丰度上升，同时毛虫被捕食的压力也会相应增加。
研究采用点计数法（point count）在冰暴实验样地与额外设置的对照样地中，于处理前后开展食虫鸟类活动监测。监测分别于2015年6月与2016年6月进行，人工冰暴施加于2016年1-2月。研究人员布设并回收了橡皮泥毛虫模型，并通过该替代物上的特征性痕迹评估捕食压力。
结果显示，冰暴样地中的树叶觅食鸟类丰度更高，且鸟类对处理的响应呈现为整体弥散性干扰效应，而非单一样地水平的响应。除1个物种外，其余所有物种在冰暴处理前后均被观测到。值得注意的是，橡皮泥毛虫模型的捕食压力并未受冰暴处理影响，而是与毛虫密度相关。冰暴处理样地内鸟类丰度的提升，佐证了其他关于鸟类对森林中小型干扰响应的研究结果；结合样地规模来看，物种组成的有限变化也符合预期。本研究结论认为，冰暴或可在干扰后的生长季为树叶觅食鸟类带来益处。
本数据集隶属于哈伯布鲁克生态研究计划（Hubbard Brook Ecosystem Study, HBES）。该计划由哈伯布鲁克实验林开展合作研究，而哈伯布鲁克实验林由美国农业部林务局北部研究站（USDA Forest Service, Northern Research Station）运营维护。