尖峰岭热带山地雨林林窗土壤甲烷通量研究

Soil methane flux of tropical mountain rainforest canopy gaps in Jianfengling,Hainan Island

以海南岛尖峰岭热带山地雨林因2012年左右台风干扰形成的林窗样地为研究对象,开展土壤甲烷通量的原位观测试验,测定林窗和林下凋落物质量、土壤温度、土壤含水量、酶活性及其他土壤理化指标,运用最佳结构模型研究土壤甲烷通量与环境因子的关系,分析林窗土壤甲烷通量变化特征、影响因素及其与林下的差异。结果表明:海南岛尖峰岭热带山地雨林表现为甲烷吸收,林窗和林下的年平均甲烷通量分别为(-0.37±0.26)和(-0.36±0.24)nmol·m^-2·s^-1,林窗和林下的土壤甲烷通量月变化特征无显著差异(P>0.05),呈现旱季高雨季低的特征。土壤甲烷通量的最佳结构模型表明,全年和旱季的林窗与林下土壤甲烷的主要调控因子均为土壤含水量,但雨季土壤甲烷调控作用最强的因子是土壤温度。结果表明,因台风形成的6个林窗短期对土壤甲烷通量没有显著影响,但林窗和林下的土壤甲烷通量具有旱季大于雨季的季节变化特征。

The in-situ flux in soil methane in six canopy gaps in the Jianfengling tropical montane rainforest of Hainan Island created by a typhoon in approximately 2012 was measured.The indicators were forest litter,soil temperature and water content,soil enzyme activity,and other soil physical and chemical properties.The relationship between soil methane flux and environmental factors was determined using the best available structural model method,and the characteristics affecting the factors and differences of methane flux were analyzed inside and outside the canopy gaps.In general,the Jianfengling tropical montane rainforest displayed a methane absorption effect.The annual average methane absorption rates inside and outside the canopy gaps were(-0.37±0.26)and(-0.36±0.24)nmol·m^-2·s^-1,respectively.No significant difference of the monthly variation in soil methane flux was evident inside and outside the canopy gaps(P>0.05).However,the flux was higher in the dry season than in the rainy season.The optimal structural model was used to understand the relationship between soil methane flux and environmental factors.Model results suggested that soil water content had the strongest negative regulation effect on the methane flux on both sides of the canopy gaps during the entire year and during the dry season,while temperature had the strongest positive effect during the rainy season.The results demonstrated that the six canopy gaps formed by the typhoon did not significantly stimulate soil methane flux,but displayed obvious seasonal characteristics.