苏北淤泥质海岸典型防护林地土壤呼吸及其温度敏感性

Soil respiration and its sensitivity to temperature in the typical shelter forests in a silting coastal area of Northern Jiangsu Province

土壤呼吸及其温度敏感性研究是准确估计陆地生态系统碳平衡对未来气候变化响应的基础。我国漫长的淤泥质海岸有着大面积的防护林,其碳汇服务功能是一个非常值得研究的科学问题,因此,对淤泥质海岸防护林生态系统土壤呼吸及其温度敏感性的研究具有重要的意义。研究采用碱液吸收法对苏北淤泥质海岸杨树Populus tomentosa Carr.及水杉Metasequoia glyptostroboides Hu＆Cheng两种典型海防林土壤呼吸及其温度敏感性进行了研究。结果表明：杨树和水杉林地4~11月份土壤呼吸速率变化范围分别为337~732mgCO2m-2h-1和257~821mgCO2m-2h-1,呼吸通量分别为128.57gCO2m-2和121.38gCO2m-2。杨树和水杉林地土壤呼吸速率季节变化均近似单峰曲线,最大值均出现在7月份,最小值分别出现在4月份和11月份。模型R=a×exp（b×T）能够很好地拟合林内气温及土壤温度变化对土壤呼吸的影响,温度是影响土壤呼吸的主要因子,能够解释土壤呼吸季节变化的50.5%~80.9%。土壤含水量与土壤呼吸关系不显著,不是其主要影响因子。利用林内气温及土壤2、5cm和10cm处温度得到杨树林地的Q10值分别为1.45、1.97、2.08、2.01,水杉林地的Q10值分别为1.92、3.29、2.89、3.00。研究结果表明,水杉林地土壤呼吸对全球变暖的响应比杨树林地更敏感。

To understand soil respiration and its sensitivity to temperature is an important basis for accurately evaluating the response of terrestrial carbon cycles to future climatic change.There is a large area of shelter forests in the long silting coast in China.In this study,soil respirations of two shelter forestlands i.e.Poplar（Populus tomentntosa Carr.） and Water fir（Metasequoia glyptostroboides） plantations were investigated in a silting coastal area of northern Jiangsu Province.Soil CO2 flux was measured in situ with the static alkali absorption method.Results showed that between Apr.and Nov.the soil respiration rate of the Poplar plantation varied from 337 to 732mgCO2m-2h-1 and that of Water fir forestland varied from 257 to 821mgCO2m-2h-1.And the total CO2 fluxes of this period were 128.57gCO2m-2 and 121.38gCO2m-2 for Poplar and Water fir plantations,respectively.Temperature was the major factor controlling soil respiration.And the soil water content was not significantly correlated with soil respiration rate and it was not a key factor to soil respiration.Forest air temperature,and 2cm,5cm,and 10cm soil depth temperatures were all significantly correlated with soil respiration rate in both plantations.The Q10 values calculated with the forest air temperature and soil temperature of 0,5,10cm depth were 1.45,1.97,2.08,2.01 for Poplar plantation,respectively and were 1.92,3.29,2.89,3.00 for water fir plantation,respectively.Soil respiration was more sensitivity to temperature in Water fir plantation than that of poplar plantation.