摘要
It was hypothesized that soil respiration can be affected by canopy composition. Hence, admixture of trees as a common forest management practice may cause significant change in the carbon cycling. This study was conducted in a mixed spruce-beech stand at Solling forest in central Germany to investigate the effect of canopy composition on soil respiration. The canopy cover was classified in four major canopy classes （pure beech, pure spruce, mixed and gap）, and the area under each canopy class was identified as a sub-plot. Soil respiration in each sub-plot （n=4） was measured monthly from Jun 2005 to July 2006. Results show significant difference in annual soil respiration between the beech （359g·m^-2·a^-1 C） and gap （211 g·m^-2·a^-1 C） sub-plots. The estimation of the total below-ground carbon allocation （TBCA） based on a model given by Raich and Nadelhoffer revealed considerably higher root CO2 production in the beech sub-plot （231 g·m^-2·a^-1 C） compare to the gap sub-plot （51 g·m^-2·a^-1 C ）. The contribution of the root respiration to the total soil respiration was higher in the soil under the beech canopy （59%） compared with the soil in the gap （29%）. The findings suggested that the condition under the beech canopy may cause more desirable micro-site for autotrophic respiration and consequently higher CO2 release into the atmosphere.
假设森林冠层组成会影响土壤呼吸,树木混交作为一种常见的林业管理措施,会引起碳循环的显著改变。在德国中部Solling云杉-山毛榉混交林开展一项研究,调查树冠层组成对土壤呼吸的作用。树冠盖度被分为4个等级:山毛榉(Fagussylvatica)覆盖层、云杉(Piceaabies)覆盖层、混交覆盖层和林分间隙,每种覆盖度选一块亚样地。2005年6月-2006年6月,每个月测定一次各样地的土壤呼吸。结果表明,山毛榉覆盖层(359g·m-2·a-1C)与林分间隙(211g·m-2·a-1C)的土壤呼吸存在显著差异。应用Raich和Nadelhoffer提出的模型对总的地下碳分配作估计,结果表明山毛榉业样地根系C02呼吸值(231g.m-2.a-1C)要比林分间隙养地的值(51g·m-2·a-1C)高许多。山毛榉冠层下的根呼吸/总土壤呼吸的比值(59%)高于林分间隙的比值(29%)。结果说明,山毛榉覆盖层下的微环境更适合土壤自养呼吸,CO2向大气排放量较高。
