苏北淤泥质海岸典型防护林地土壤呼吸组分分离

Components separation of soil respiration in two typical shelter forestlands in silting coastal area,Northern Jiangsu Province

土壤呼吸组分分离研究在理解生态系统土壤CO2释放对气候变化的响应研究中具有重要的意义。采用挖壕沟法对苏北淤泥质海岸两种典型防护林地土壤呼吸组分进行了分离研究。结果表明:杨树和水杉林地的根呼吸、异养呼吸与土壤总呼吸的季节变化相似,6—9月份较高,其它月份较低。杨树(Populus tomentosa Carr.)和水杉(Metasequoia glyptostroboides Hu&Cheng)林地根系呼吸的年通量分别为767.5gCO2m-2和902.8g CO2m-2,根呼吸对土壤总呼吸的贡献分别为20.2%和25.0%。杨树和水杉林地土壤异养呼吸对土壤总呼吸的贡献均远大于根呼吸,分别是根呼吸的3.9倍和3.0倍。温度是两林地土壤呼吸各组分的主要限制性因子,而土壤含水量不是土壤呼吸组分的限制性因子。本研究结果表明,苏北沿海防护林地的根呼吸对土壤总呼吸的贡献较小。为了能够更加准确的定量估算土壤呼吸各组分,在未来组分分离研究中应加强同位素法的应用。

There is great significance for the research on the components separation of soil respiration in response to climate change.The trench method had been used in our study to separate components of soil respiration in two typical shelter forestlands,i.e.Poplar（Populus tomentosa Carr.） plantation and Water fir（Metasequoia glyptostroboides Hu Cheng） plantation,in a silting costal area of Northern Jiangsu Province.It was showed that there were similar seasonal dynamics for root respiration,heterotrophic respiration and total soil respiration in both plantations：higher respiration rate between Jun.and sept.and lower in the other months;the annual CO2 flux of root respiration of Poplar and Water fir plantations was 767.5 g m-2and 902.8g m-2,respectively,which was far less than that of the corresponding annul heterotrophic respiration flux that was 2.9 and 2.0 times larger than that of the corresponding root respiration components,respectively.In both plantations,temperature was the key limiting factors for both of the soil respiration components,but soil water content was not the control factor in the experiment period.Our results showed that in this silting coastal area,root respiration contributed less to the total soil respiration than the heterotrophic component for both shelter forests.To estimate the contribution of components to the total soil respiration more accurately,isotope method should be used in the future studies.