Schuldt Andreas, Bruelheide Helge, Härdtle Werner, Assmann Thorsten, Li Ying, Ma Keping, von Oheimb Goddert, Zhang Jiayong
Institute of Ecology, Leuphana University Lüneburg Scharnhorststr. 1, D-21335, Lüneburg, Germany.
Institute of Biology/Geobotany and Botanical Garden, University of Halle Am Kirchtor 1, D-06108, Halle, Germany ; German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig Deutscher Platz 5e, D-04103, Leipzig, Germany.
J Ecol. 2015 May;103(3):563-571. doi: 10.1111/1365-2745.12396. Epub 2015 Mar 28.
Despite the importance of herbivory for the structure and functioning of species-rich forests, little is known about how herbivory is affected by tree species richness, and more specifically by random vs. non-random species loss. We assessed herbivore damage and its effects on tree growth in the early stage of a large-scale forest biodiversity experiment in subtropical China that features random and non-random extinction scenarios of tree mixtures numbering between one and 24 species. In contrast to random species loss, the non-random extinction scenarios were based on the tree species' local rarity and specific leaf area - traits that may strongly influence the way herbivory is affected by plant species richness. Herbivory increased with tree species richness across all scenarios and was unaffected by the different species compositions in the random and non-random extinction scenarios. Whereas tree growth rates were positively related to herbivory on plots with smaller trees, growth rates significantly declined with increasing herbivory on plots with larger trees. Our results suggest that the effects of herbivory on growth rates increase from monocultures to the most species-rich plant communities and that negative effects with increasing tree species richness become more pronounced with time as trees grow larger. . Our results indicate that key trophic interactions can be quick to become established in forest plantations (i.e. already 2.5 years after tree planting). Stronger herbivory effects on tree growth with increasing tree species richness suggest a potentially important role of herbivory in regulating ecosystem functions and the structural development of species-rich forests from the very start of secondary forest succession. The lack of significant differences between the extinction scenarios, however, contrasts with findings from natural forests of higher successional age, where rarity had negative effects on herbivory. This indicates that the effects of non-random species loss could change with forest succession.
尽管食草作用对物种丰富的森林的结构和功能至关重要，但对于食草作用如何受到树种丰富度的影响，尤其是随机与非随机物种丧失的影响，我们却知之甚少。在中国亚热带地区进行的一项大规模森林生物多样性实验的早期阶段，我们评估了食草动物的损害及其对树木生长的影响，该实验设置了1至24种树木混合的随机和非随机灭绝情景。与随机物种丧失不同，非随机灭绝情景是基于树种的当地稀有性和比叶面积——这些特征可能会强烈影响食草作用受植物物种丰富度影响的方式。在所有情景中，食草作用都随着树种丰富度的增加而增加，并且不受随机和非随机灭绝情景中不同物种组成的影响。在小树地块上，树木生长速率与食草作用呈正相关，而在大树地块上，随着食草作用的增加，生长速率显著下降。我们的研究结果表明，食草作用对生长速率的影响从单一栽培到物种最丰富的植物群落逐渐增加，并且随着树木生长得更大，随着树种丰富度增加的负面影响会变得更加明显。我们的研究结果表明，关键的营养相互作用在人工林中能够很快建立起来（即植树后仅2.5年）。随着树种丰富度的增加，食草作用对树木生长的影响更强，这表明食草作用在从次生林演替一开始就调节生态系统功能和物种丰富的森林的结构发展方面可能发挥着重要作用。然而，灭绝情景之间缺乏显著差异，这与更高演替年龄的天然林的研究结果形成对比，在天然林中，稀有性对食草作用有负面影响。这表明非随机物种丧失的影响可能会随着森林演替而变化。
