不同苔藓斑块对亚高山针叶林土壤呼吸和有机碳累积的影响

Effects of Different Moss Patches on Soil Respiration and Organic Carbon Accumulation in Subalpine Coniferous Forests

苔藓植物作为森林生态系统最常见的地被植物之一,对生态过程起着重要调控作用。为探明不同苔藓植物对亚高山生态系统碳循环过程的影响,本文以封闭式动态气室法,对川西贡嘎山东坡峨眉冷杉生态系统赤茎藓(Pleuroziu schreberi)和星塔藓(Hylocomiastrum pyrenaicum)两种苔藓斑块土壤以及裸地斑块土壤CO_2排放速率进行了定位观测,同时探讨了不同苔藓斑块对土壤有机碳累积的影响及潜在途径。结果显示:(1)苔藓植物显著改变了亚高山针叶林土壤CO_2排放速率及其季节变化特征,但不同苔藓植物的影响程度具有差异:赤茎藓和星塔藓作用下土壤CO_2排放速率分别增加了28.5%和46.8%,星塔藓与赤茎藓相比其对土壤CO_2排放的促进作用更显著;(2)苔藓斑块对土壤有机碳(SOC)和溶解性有机碳(DOC)的影响具有物种特异性,两种苔藓中,赤茎藓能够显著促进SOC和DOC累积,但星塔藓的影响不显著。该结果反映了亚高山生态系统不同苔藓物种在促进生态系统碳循环方面的生态功能的差异,由此,在开展亚高山生态系统碳循环以及土壤有机碳储量研究时,应充分考虑苔藓物种对土壤碳过程/碳平衡的作用机制和生态功能差别。

Bryophytes are one of the dominating vegetative communities in the bottom layer of subalpine and other related ecosystems,and play an important role in regulating ecological processes.In this study,carbon dioxide (CO2) emission rates from bare soil,bryophytes Pleuroziu schreberi- and Hylocomiastrum pyrenaicum -covered soils were investigated in a subalpine coniferous forest in the Gongga Mountain,western Sichuan,China,in order to reveal the roles of bryophyte patches in regulating soil C cycling processes.And then it compared the accumulation of soil organic carbon (SOC) in the mentioned soils.Results suggested that bryophyte patches significantly increased CO2 emission rates,with an increase of CO2 emission rates 28.5% and 46.8% in the P.schreberi - and H.pyrenaicum -covered soils,respectively,than one in bare soil.Compared with bryophyte-covered soils,the bare soil had a larger seasonal variation in CO2 emission rates.Accumulation of SOC and dissolved organic carbon (DOC) were promoted by P.schreberi but not by H.pyrenaicum,suggesting a species-specific impact of bryophyte patches on these parameters.The results demonstrate the different ecological roles of bryophyte species in regulating C cycling in subalpine forest ecosystems,which should be included into the modelling of carbon cycling in advanced research.