Plant litter decomposition is a key ecological process that is mostly studied at the forest floor. However, decomposition generally starts in the canopy. In this study, we evaluated the effect of litter composition and climate on the initial phase of decomposition in the soil and two contrasting types of canopy microsites along an elevational gradient (0–2200 m a.s.l.). To this end, we incubated standard material composed by green (fast decomposing) and rooibos (slow decomposing) tea bags for three months. Tea bags were placed in soil (buried at 5 cm) and in the canopy at ca. 5 m above the ground in “micro-wetlands” (tank bromeliads) and dry crown microsites (branches). Along the elevational gradient, green tea decomposed faster than rooibos tea in all microsites and forests. Mass loss for both tea types was lowest on branches at all sites, except for green tea in a wet forest where decomposition did not significantly differ among microsites. In wet forests, decomposition did not differ between bromeliads and soil, while in a dry forest, decomposition was faster in bromeliads. We found that the effects of climatic variables [monthly average temperature (TEMP) and total precipitation (PREC) for the incubation months] on decomposition differed between microsites. Along the elevational gradient, the mass loss in soil was positively correlated with TEMP but not with PREC, whereas on branches, mass loss was negatively correlated with TEMP and positively correlated with PREC. Unlike on branches, mass loss in bromeliads slightly decreased with PREC and increased with TEMP. Our study shows that microsite conditions interact with climate (TEMP and PREC) leading to differences in the general decomposition patterns in the forest canopy.

中文翻译：

---

区域尺度土壤和森林冠层的微型站点和早期凋落物分解模式

植物凋落物分解是一个关键的生态过程，主要在森林地面进行研究。然而，分解通常从树冠开始。在这项研究中，我们评估了凋落物成分和气候对土壤分解初始阶段的影响，以及沿海拔梯度 (0-2200 m asl) 的两种对比类型的冠层微型场地。为此，我们孵化了由绿色（快速分解）和路易波士（缓慢分解）茶包组成的标准材料三个月。茶包被放置在土壤中（埋在 5 厘米处）和大约在树冠中。距地面 5 m 的“微型湿地”（水箱凤梨科植物）和干树冠微型场所（树枝）。沿着海拔梯度，绿茶在所有微型地点和森林中的分解速度都比路易波士茶快。两种茶的质量损失在所有地点的树枝上都是最低的，除了在潮湿森林中的绿茶，其中微型站点之间的分解没有显着差异。在潮湿的森林中，凤梨科植物和土壤的分解没有差异，而在干燥的森林中，凤梨科植物的分解速度更快。我们发现气候变量 [孵化月份的月平均温度 (TEMP) 和总降水量 (PREC)] 对分解的影响因微型站点而异。沿海拔梯度，土壤质量损失与TEMP呈正相关，与PREC不相关，而在树枝上，质量损失与TEMP呈负相关，与PREC呈正相关。与树枝不同，凤梨科植物的质量损失随 PREC 略有减少，随 TEMP 增加。