J.F. Blumenbach Institute of Zoology and Anthropology, Georg August University Göttingen, Berliner Str. 28, 37073, Göttingen, Germany.
Centre of Biodiversity and Sustainable Land Use, Von-Siebold-Str. 8, 37075, Göttingen, Germany.
Microb Ecol. 2017 Oct;74(3):681-690. doi: 10.1007/s00248-017-0980-4. Epub 2017 Apr 7.
We investigated the role of leaf litter chemistry and richness in affecting testate amoeba communities of tropical rainforest in the Ecuadorian Andes. Litterbags containing leaf litter from four dominating tree species (Clusia sp., Myrcia pubescens, Graffenrieda emarginata, and Cecropia andina) with richness 1, 2, and 4 species were established and exposed in the field for 12 months at 2000 m a.s.l. Chemical elements and compounds of leaf litter were analyzed before exposure. At the end of exposure, microbial biomass and litter mass loss were measured, and living testate amoeba species number, density, biomass, and community composition were determined. In total, 125 testate amoeba species colonized the litter in litterbags. The results suggest that high litter nitrogen and low lignin concentrations are indicators of high litter quality for testate amoebae density and species richness. Their species number and density significantly declined in the order 1 > 4 > 2 leaf litter species and varied with leaf litter chemistry being at a maximum in high-quality single leaf litter species and low in low-quality leaf litter. Further, the addition of litter of high-quality to low-quality litter increased testate amoebae biomass and density; however, the values did not exceed the ones in single high-quality litter treatments. Moreover, the structure of testate amoeba communities varied with litter chemistry, with Fe, Na, lignin, and litter C-to-N ratio being of major importance, and indicating that litter chemistry reflects habitat quality for testate amoebae. Overall, the data show that leaf litter chemistry overrides leaf litter richness in structuring testate amoeba communities.
我们研究了落叶化学性质和丰富度在影响厄瓜多尔安第斯山脉热带雨林测试变形虫群落中的作用。含有四种主要树种（Clusia sp.、Myrcia pubescens、Graffenrieda emarginata 和 Cecropia andina）落叶的落叶袋，丰富度为 1、2 和 4 种，在海拔 2000 米的野外暴露 12 个月。在暴露之前，分析了落叶的化学元素和化合物。暴露结束时，测量了微生物生物量和落叶质量损失，并确定了活体测试变形虫物种数量、密度、生物量和群落组成。总共 125 种测试变形虫物种在落叶袋中的落叶上定殖。结果表明，高落叶氮和低木质素浓度是指示落叶质量高的指标，有利于测试变形虫的密度和物种丰富度。它们的物种数量和密度按 1>4>2 落叶物种的顺序显著下降，落叶化学性质的变化最大，高质量单落叶物种最高，低质量落叶最低。此外，高质量落叶对低质量落叶的添加增加了测试变形虫的生物量和密度；然而，这些值没有超过高质量单落叶处理的值。此外，测试变形虫群落的结构随落叶化学性质而变化，Fe、Na、木质素和落叶 C/N 比是主要因素，表明落叶化学性质反映了测试变形虫的栖息地质量。总的来说，数据表明落叶化学性质在构建测试变形虫群落方面优于落叶丰富度。
