Habitat specific effects of bark on wood decomposition: influences of fragmentation, nitrogen concentration, and microbial community composition

1.    Identifying the drivers of decomposition is critical for understanding carbon cycling dynamics in forest ecosystems. Woody biomass is an important pool of carbon, composed of bark and underlying wood that differ in structure, nutrient concentrations, and exposure to the environment. We hypothesized that higher nutrient concentrations in bark would speed the decomposition of underlying wood, and that this effect would be greater in streams, where nutrients are less available to decomposers than on land.
2.      Replicate branches of three tree species, with and without bark, were placed in streams and on land in a lowland tropical forest in Panama. After 3 and 11 months of decomposition, we measured mass loss and nitrogen (N) concentrations and sequenced the fungal and bacterial communities of both wood and bark tissues.
3.      While bark decomposed faster than the underlying wood and had higher N concentrations, bark presence slowed wood mass loss. Nitrogen concentration could ...

1. 明确分解过程的驱动因子，对于理解森林生态系统中的碳循环动态至关重要。木质生物量（woody biomass）是重要的碳库，由树皮与内部木质组织构成，二者在结构、养分浓度以及环境暴露特征上均存在显著差异。本研究提出如下假说：树皮内较高的养分浓度会加速内部木质组织的分解，且该效应在溪流生境中更为显著——相较于陆地生境，溪流环境中分解者可获取的养分更为匮乏。
2. 我们选取3个树种的重复枝条，分别设置保留树皮与去除树皮两组处理，将其布设于巴拿马低地热带森林的溪流与陆地生境中。经过3个月与11个月的分解培养后，我们测定了样品的质量损失率与氮（N）浓度，并对木质与树皮组织的真菌和细菌群落进行了测序。
3. 尽管树皮的分解速率快于内部木质组织，且其氮浓度更高，但保留树皮反而会降低木质组织的质量损失率。氮浓度可……