Data from: Nutrient limitation or home field advantage: does microbial community adaptation overcome nutrient limitation of litter decomposition in a tropical peatland?

Litter decomposition is an important control on carbon accumulation in tropical peatlands. Stoichiometric theory suggests that decomposition is regulated by elemental ratios in litter while the home field advantage (HFA) hypothesis predicts that decomposer communities are adapted to local conditions. To date, the relative importance of these contrasting theories for litter decomposition and therefore the carbon balance of tropical peatlands remain poorly understood.
We conducted two in situ litter decomposition experiments in a lowland tropical peatland. The first experiment tested the importance of the stoichiometric theory using a factorial nutrient addition experiment at two sites with contrasting vegetation (Raphia taedigera and Campnosperma panamensis) to assess how nutrient addition affected microbial enzyme activity and litter mass loss at the peat surface and at 50 cm depth. The second experiment tested the importance of HFA by reciprocal translocation of leaf litter from R. taedigera and C. panamensis forests, which differed in both litter chemistry and soil nutrient availability, to separate the influence of litter chemistry and soil/site properties on litter mass loss.
The activities of hydrolytic enzymes involved in the decomposition of large plant polymers were stimulated by nitrogen addition only where nitrogen availability was low relative to phosphorus, and were stimulated by phosphorus addition where phosphorus availability was low.
The addition of nitrogen, but not phosphorus, increased leaf litter decomposition under waterlogged conditions at 50 cm depth, but not at the peat surface.
Decomposition was greatest for autochthonous litter irrespective of site nutrient status, indicating that adaptation of the microbial community to low nutrients can partly overcome nutrient limitation, and suggesting that HFA can influence litter decomposition rates.
Synthesis. Our study shows that leaf litter decomposition and the activity of microbial enzymes in tropical peatlands are constrained in part by nutrient availability. However, such nutrient limitation of litter decomposition can be overcome by adaptation of the microbial community.

枯落物分解是调控热带泥炭地碳积累的关键过程。化学计量理论指出，枯落物分解受枯落物元素比例调控；而原位优势（home field advantage, HFA）假说则预测，分解者群落会适应本地环境条件。迄今为止，这两种对立理论对于热带泥炭地枯落物分解乃至碳平衡的相对重要性，仍未得到充分阐释。

本研究在低地热带泥炭地开展了两项原位枯落物分解实验。第一项实验通过因子式养分添加实验，在植被类型迥异的两个样地（Raphia taedigera与Campnosperma panamensis林）中验证化学计量理论的重要性，以探究养分添加如何影响泥炭地表层及50厘米深度处的微生物酶活性与枯落物质量损失率。第二项实验则通过将R. taedigera与C. panamensis林的叶片枯落物进行相互易位（两种枯落物的化学组成与土壤养分有效性均存在差异），以此分离枯落物化学性质与土壤/样地属性对枯落物质量损失率的影响，从而验证HFA假说的重要性。

参与大型植物聚合物分解的水解酶活性，仅在氮相对磷有效性较低的样地中会因氮添加而提升，且仅在磷相对氮有效性较低的样地中会因磷添加而提升。

在50厘米深度的淹水条件下，氮添加（而非磷添加）可提升叶片枯落物的分解速率，但该效应并未出现在泥炭地表层。

无论样地养分状况如何，本地枯落物的分解速率均为最高，这表明微生物群落对低养分环境的适应可部分抵消养分限制效应，同时也说明HFA可对枯落物分解速率产生影响。

综合分析。本研究表明，热带泥炭地的叶片枯落物分解与微生物酶活性，在一定程度上受养分有效性的制约。但枯落物分解的这类养分限制效应，可通过微生物群落的适应作用得到缓解。