石漠化区蚬木天然林土壤呼吸动态变化及其影响因素

摘要

蚬木(Excentrodendron hsienmu) 林是桂西南石灰岩季节性雨林最具代表性的顶极演替群落,但对该群落类型碳循环过程的研究相对较少.本研究通过对石漠化区蚬木林土壤呼吸动态及其影响因子的测定和分析,研究蚬木林土壤呼吸的动态变化规律及驱动机制.结果表明:蚬木林土壤呼吸日变化与土壤温度呈正相关性,在非生长季的11月两者相关性达到显著水平.土壤呼吸季节动态与土壤温度、日最低气温呈显著正相关性,呈现夏季高、冬季低的特征,与土壤呼吸呈微弱正相关.基于日最低气温和土壤湿度的双因子模型对土壤呼吸拥有最佳拟合效果,可解释土壤呼吸季变异的71.0%.采用基于日最低气温的单因子模型计算得到土壤呼吸CO2通量为54.61 t/(hm2·a);扣除地表裸露岩石后,土壤呼吸CO2通量为12.95 t/(hm2·a).蚬木林土壤呼吸的动态变化与同气候带森林相似;仅考虑土壤覆盖时,土壤呼吸碳通量处于相对较高水平.%Excentrodendron hsienmu forest was the most representative climax community of monsoon forest in limestone region in southwest of Guangxi.However,the studies of carbon cycle in E.hsienmu ecosystem were insufficient so far.Soil respiration and its environmental factors had been measured and analyzed in E.hsienmu forest to reveal the dynamics and driving mechanism of E.hsienmu ecosystem.Results showed that soil respira-tion rate had positive relationship with soil temperature during daytime,and the relationship reached signifi-cant level in November.Soil respiration rate varied markedly during the year with higher rates in summer and lower rates in winter. The two-factors model based on daily minimum air temperature and soil moisture had best fitting effect for soil respiration rate,and could explain 71.0% variation of soil respiration.The CO2 flux of soil respiration calculated by single-factor model based on daily minimum air temperature was 54.61 t/(hm2· a).The CO2flux of soil respiration was 12.95 t/(hm2·a)while taking out bare rock covers of surface.The dy-namic change of soil respiration of E.hsienmu was similar to the forest with the same climate zone.Considered the soil cover,the CO2flux of soil respiration reached relative high level.