There are different components of carbon (C) pools in a natural forest ecosystem: biomass, soil, litter and woody debris. We asked how these pools changed with elevation in one of China’s ecologically important forest ecosystem, i.e. beech (Fagus L., Fagaceae) forests, and what were the underlying driving factors of such variation.
The four C pools in nine beech forests were investigated along an elevational gradient (1095–1930 m) on Mt. Fanjingshan in Guizhou Province, Southwest China. Variance partitioning was used to explore the relative effects of stand age, climate and other factors on C storage. In addition, we compared the four C pools to other beech forests in Guizhou Province and worldwide.
The total C pools of beech forest ecosystems ranged from 190.5 to 504.3 Mg C ha–1, mainly attributed to biomass C (accounting for 33.7–73.9%) and soil C (accounting for 23.9–65.5%). No more than 4% of ecosystem C pools were stored in woody debris (0.05–3.1%) and litter (0.2–0.7%). Ecosystem C storage increased significantly with elevation, where both the biomass and woody debris C pools increased with elevation, while those of litter and soil exhibited no such trend. For the Guizhou beech forests, climate and stand age were found to be key drivers of the elevational patterns of ecosystem and biomass C storage, while for beech forests globally, stand age was the most important predictor. Compared to beech forests worldwide, beech forests in Guizhou Province displayed a relatively higher biomass C accumulation rate, which may be explained by a much higher precipitation in this area. The present study provides basic data for understanding the C budgets of Chinese beech forests and their possible roles in regional C cycling and emphasizes the general importance of stand age and climate on C accumulation.
森林生态系统碳库通常包括植被、土壤、凋落物与木质残体等几个组分。本研究旨在探讨中国一种重要的森林生态系统—水青冈林(Fagus L.)中这些碳库的沿海拔梯度格局变化及其驱动因子。在中国贵州省梵净山,沿海拔梯度(1095–1930 m)调查了9个水青冈林各碳库的碳储量。采用方差分解探讨了林龄、气候及其他因子对碳储量的影响,同时对梵净山与贵州和全球其他地区水青冈林的碳储量进行了比较。梵净山水青冈林生态系统碳储量在190.5–504.3 Mg C ha–1之间,其主要组分包括植被碳库(33.7–73.9%)和土壤碳库(23.9–65.5%),而木质残体(0.05–3.1%)和凋落物(0.2–0.7%)对该生态系统碳储量的贡献不超过4%。随海拔升高,生态系统碳储量呈增加趋势,其中植被与木质残体碳库增加,而凋落物与土壤碳库无明显的变化趋势。对梵净山水青冈林,气候与林龄是其各组分碳储量海拔格局形成的主要原因；而对于全球水青冈林,林龄是其碳储量变化的主导因子。相比全球其他地区的水青冈林,贵州水青冈林具有较高的植被碳储量积累速率,这可能与贵州较高的降水量有关。本研究结果有助于理解中国水青冈林碳收支及其在区域碳循环中的可能作用,同时强调了林龄与气候对碳积累的重要性。