马尾松人工林根呼吸的季节变化及影响因子

Seasonal Variation of Root Respiration and the Controlling Factors in Pinus massoniana Plantation

2007年1月至2008年12月,以长沙天际岭国家森林公园马尾松群落为研究对象,采用挖壕法研究马尾松群落去除根系后土壤呼吸速率动态及其与土壤温、湿度的相关关系。结果表明:马尾松群落和去除根系处理的土壤呼吸年变化范围分别为0.29～3.19,0.25～2.33μmol·m-2s-1,年均分别为1.56,1.03μmol·m-2s-1。去除根系土壤呼吸速率比对照降低12.2%～55.1%,根呼吸年均贡献率为28.3%。马尾松群落和去除根系的土壤呼吸速率与5cm土壤温度之间均呈显著指数相关,温度敏感系数Q10值分别为2.10和1.82,估算出根呼吸的Q10值为2.94。马尾松群落和去除根系的土壤呼吸速率与土壤湿度之间相关关系均不显著(P﹥0.05),但根呼吸与土壤湿度之间呈显著线性相关(P=0.023)。

This study aims at revealing seasonal changes of soil respiration（ Rs） without roots and its relationship with soil temperature and humility at 5 cm depth in a Pinus massoniana plantation in the Tianjiling National Forest Park （113°01′—113°02′ E,28°06′—28°07′ N） of Changsha,Hunan Province,China. A trenching method,in which the roots existing in a given area were severed at the plot boundary but not removed,was used to determine the contribution of the root respiration to total soil CO2 efflux. The Rs rates were measured from January 2007 to December 2008 by using infrared gas exchange analyzer of Li-Cor 6400-09. The results showed the rates of soil CO2 efflux in the trenched and control plots ranged 0. 25-2. 33 and 0. 29-3. 19 μmol ·m-2 s-1 respectively. The mean annual Rs in the trenched and control plots was 1. 03 and 1. 56 μmol·m-2 s-1 ,respectively. The Rs rates in trenched plots were decreased by 12. 2% ～ 55. 1% when compared with the control plots. Therefore,an annual value of the roots contributed around 28. 3% of the total soil respiration. There was a significant exponential relationship between Rs in the trenched plots and the soil temperature. The Q10 value,representing the sensitivity of Rs to soil temperature,was lower in the trenched plots （1. 82） than the control plots （2. 10）,The Q10 value of root respiration was estimated 2. 94. There was no significant relationship found between the Rs rates in the trenched plots and the soil humility,however relationship between the root respiration and the soil humidity could be well described by a linear equation： y = 0. 019w ＋ 0. 209,R2 = 0. 154,P = 0. 023.