Wu Xinwei, Cao Rui, Wei Xue, Xi Xinqiang, Shi Peili, Eisenhauer Nico, Sun Shucun
Department of Ecology, College of Life Sciences, Nanjing University, Nanjing 210023, China.
Center for Ecological Studies, Chengdu Institute of Biology, 9 Section 4 Renminnan Rd, Chengdu 610041, China.
J Appl Ecol. 2017 Feb 24;54(5):1291-1300. doi: 10.1111/1365-2664.12894.
Human activities have been a significant driver of environmental changes with tremendous consequences for carbon dynamics. Peatlands are critical ecosystems because they store ~30% of the global soil organic carbon pool and are particularly vulnerable to anthropogenic changes. The Zoige peatland on the eastern Tibet Plateau, as the largest alpine peatland in the world, accounts for 1‰ of global peat soil organic carbon storage. However, this peatland has experienced dramatic climate change including increased temperature and reduced precipitation in the past decades, which likely is responsible for a decline of the water table and facilitated earthworm invasion, two major factors reducing soil organic carbon (SOC) storage of peatlands. Because earthworms are often more active in low- than in high- moisture peatlands, we hypothesized that the simultaneous occurrence of water table decline and earthworm invasion would synergistically accelerate the release of SOC from peatland soil. We conducted a field experiment with a paired split-plot design, i.e. presence vs. absence of the invasive earthworms () nested in drained vs. undrained plots, respectively, for three years within the homogenous Zoige peatland. Water table decline significantly decreased soil water content and bulk density, resulting in a marked reduction of SOC storage. Moreover, consistent with our hypothesis, earthworm presence dramatically reduced SOC in the drained but not in the undrained peatland through the formation of deep burrows and decreasing bulk density of the lower soil layer over three years. The variation in SOC likely was due to changes in aboveground plant biomass, root growth, and earthworm behavior induced by the experimental treatments. We suggest that incentive measures should be taken to prevent further water table decline and earthworm invasion for maintaining the soil C pool in Zoige peatland. Artificial filling of drainage canals should be implemented to increase the water table level, facilitating the recovery of drained peatlands. Moreover, the dispersal of earthworms and their cocoons attached to the roots of crop plants and tree saplings from low-lying areas to the Zoige region should be controlled and restricted.
人类活动一直是环境变化的重要驱动因素，对碳动态产生了巨大影响。泥炭地是关键的生态系统，因为它们储存了全球约30%的土壤有机碳库，并且特别容易受到人为变化的影响。位于青藏高原东部的若尔盖泥炭地是世界上最大的高寒泥炭地，占全球泥炭土壤有机碳储量的1‰。然而，在过去几十年里，这片泥炭地经历了剧烈的气候变化，包括气温升高和降水减少，这可能导致了地下水位下降和蚯蚓入侵，这是减少泥炭地土壤有机碳（SOC）储量的两个主要因素。由于蚯蚓通常在低湿度而非高湿度的泥炭地中更活跃，我们假设地下水位下降和蚯蚓入侵同时发生会协同加速泥炭地土壤中SOC的释放。我们在均质的若尔盖泥炭地内进行了一项为期三年的田间试验，采用配对裂区设计，即分别在排水和未排水的地块中设置有无入侵蚯蚓（ ）的处理。地下水位下降显著降低了土壤含水量和容重，导致SOC储量显著减少。此外，与我们的假设一致，蚯蚓的存在通过形成深洞穴和在三年内降低下层土壤的容重，显著降低了排水泥炭地而非未排水泥炭地中的SOC。SOC的变化可能是由于实验处理引起的地上植物生物量、根系生长和蚯蚓行为的变化。我们建议应采取激励措施，防止地下水位进一步下降和蚯蚓入侵，以维持若尔盖泥炭地的土壤碳库。应实施人工填充排水渠道以提高地下水位，促进排水泥炭地的恢复。此外，应控制和限制蚯蚓及其附着在作物植物和树苗根部的茧从低洼地区扩散到若尔盖地区。
