Latitudinal pattern in community-wide herbivory does not match the pattern in herbivory averaged across common plant species

1. The latitudinal herbivory hypothesis (LHH) predicts that plant losses to herbivores decrease from low to high latitudes. Although the LHH is a community-level hypothesis, it has been rarely tested with data on community-wide herbivory, i.e. the percentage of annual production of foliar biomass consumed by insects from all plant species at a given site. Therefore, we asked whether community-wide leaf herbivory follows the same latitudinal pattern as observed for an unweighted average of herbivory across common plant species.

2. We selected ten study sites in boreal forests from 60°N to 69°N along 1000 km long latitudinal gradient in NW Russia. We measured relative foliar losses to insect herbivores in seven woody plant species (jointly comprising over 95% of the community-wide aboveground biomass) and estimated their current-year foliar biomass. We averaged leaf herbivory for all seven species and calculated community-wide leaf herbivory by weighting the relative foliar losses of e..., On August 17–22, 2014, when the majority of insect herbivores had completed their feeding, at each site we haphazardly selected five (deciduous plants) to ten (coniferous plants) mature individuals of each of the seven species. Each plant was located at least 10 m apart from others of its species. From each of the deciduous individuals, we collected a haphazardly selected branch with approximately 80–120 leaves. In conifers, we collected a haphazardly selected branch with 120–200 current-year needles. To avoid the impact of unconscious biases on the values of herbivory, the tree branches and bilberry stems were selected while standing at a distance of 5‒10 m away, which does not allow visual evaluation of leaf damage by insects. Leaf herbivory was measured in the laboratory within two days from sampling. In broadleaved species, the leaves on each branch were counted, and each leaf was carefully examined for the presence of damage imposed by chewing insect herbivores (both miners and def..., Columns in the data file (space-separated) contain the following information:

Column 1: Latitude of study site (degrees N).

Column 2: Plant name (genus_species).

Column 3: Plant-specific percentage of leaf area consumed by insects.

1. 纬度植食假说（latitudinal herbivory hypothesis, LHH）预测，植食动物造成的植物损失随纬度从低到高逐渐降低。尽管该假说属于群落层面的理论，但目前极少有研究采用群落尺度植食数据（community-wide herbivory，即特定样地内所有植物物种的昆虫取食叶生物量年生产量占比）开展检验。因此本研究旨在探讨群落尺度叶片植食率（community-wide leaf herbivory）是否遵循与常见植物物种植食率非加权平均值一致的纬度分布格局。
2. 本研究在俄罗斯西北部沿1000公里纬度梯度的寒温带森林中设置了10个研究样地，样地纬度范围为60°N至69°N。我们测定了7种木本植物的昆虫相对叶损失率（该7个物种合计占群落地上生物量的95%以上），并估算了它们的当年生叶生物量。我们对7个物种的叶片植食率进行了平均，并通过加权各物种的相对叶损失率计算群落尺度叶片植食率[原文此处存在截断]，2014年8月17–22日，当多数昆虫植食者完成取食活动时，我们针对7个物种中的每一种，随机选取成熟个体：落叶植物选取5株，针叶植物选取10株，且每株同种个体之间的间距至少为10米。从每株落叶植物个体上，随机采集1根带有约80~120片叶片的枝条；对于针叶植物，则采集1根带有120~200枚当年生针叶的随机枝条。为避免主观偏差对植食率测定结果的影响，我们在距离植株5~10米的位置选取枝条与越橘茎秆，该距离下无法目视评估昆虫造成的叶片损伤。叶片植食率在采样完成后的两天内于实验室完成测定。对于阔叶树种，我们统计每根枝条上的叶片数量，并逐一检查每片叶片是否存在咀嚼式昆虫植食者（包括潜叶虫与食叶昆虫）造成的损伤。
数据文件以空格符分隔，各列包含的信息如下：
第1列：研究样地的纬度（北纬度数）。
第2列：植物名称（属_种）。
第3列：该植物物种被昆虫取食的叶面积百分比。