Edge effects on moisture reduce wood decomposition rate in a temperate forest
Edge effects on moisture reduce wood decomposition rate in a temperate forest
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DOI：
10.1111/gcb.12676
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发表时间：
2015-02-01
影响因子：
11.6
通讯作者：
Bebber, Daniel P.
中科院分区：
文献类型：
--
作者：
Crockatt, Martha E.;Bebber, Daniel P.
世界各地的森林日益破碎，森林小气候的边缘效应有可能影响碳和养分循环等生态系统功能。由于日照、风和蒸散的影响，边缘往往更加干燥和温暖，这些梯度可以深入森林数百米。凋落物分解是碳循环的关键组成部分，这在很大程度上是由对温度和湿度变化做出反应的腐生真菌控制的。然而，人们对森林破碎化对凋落物腐烂的影响知之甚少。在这里，我们使用实验方法研究了温带森林中木材腐烂的边缘效应，在两年多的时间内监测从森林边缘到核心 100m 横断面放置的木块的质量损失。分解速率随着距边缘距离的增加而增加，并且与腐烂木材的湿度和含水量的增加相关，使得100m处的腐烂常数几乎是边缘处的两倍。平均气温随着距边缘距离的增加而略有下降。边缘效应引起的衰减常数的变化大于根据已发布的区域模型对气候变化进行合理估计所预期的变化。我们使用英国各地距边缘不同距离内的森林面积函数，模拟了景观尺度上边缘效应对衰减常数的影响。我们发现，与假设没有边缘效应的估计相比，考虑边缘效应将使衰减率降低近四分之一。
Forests around the world are increasingly fragmented, and edge effects on forest microclimates have the potential to affect ecosystem functions such as carbon and nutrient cycling. Edges tend to be drier and warmer due to the effects of insolation, wind, and evapotranspiration and these gradients can penetrate hundreds of metres into the forest. Litter decomposition is a key component of the carbon cycle, which is largely controlled by saprotrophic fungi that respond to variation in temperature and moisture. However, the impact of forest fragmentation on litter decay is poorly understood. Here, we investigate edge effects on the decay of wood in a temperate forest using an experimental approach, whereby mass loss in wood blocks placed along 100m transects from the forest edge to core was monitored over 2years. Decomposition rate increased with distance from the edge, and was correlated with increasing humidity and moisture content of the decaying wood, such that the decay constant at 100m was nearly twice that at the edge. Mean air temperature decreased slightly with distance from the edge. The variation in decay constant due to edge effects was larger than that expected from any reasonable estimates of climatic variation, based on a published regional model. We modelled the influence of edge effects on the decay constant at the landscape scale using functions for forest area within different distances from edge across the UK. We found that taking edge effects into account would decrease the decay rate by nearly one quarter, compared with estimates that assumed no edge effect.