蚂蚁在西双版纳不同演替阶段热带森林土壤二氧化碳排放中的作用及其机制

The ants in tropical rain forests of Xishuangbanna are the most abundant in China. The ant activity can result in significant change in soil physical-chemical properties, soil microbial community and soil organic carbon mineralization, which may have strong influence on the spatial-temporal dynamic of soil CO2 emissions. In situ determination method of alkali absorption and Li6400-09 were used to examine the dynamics of soil CO2 and identified the influence of space-time patterns in anthills on the efflux of soil CO2 in 4 kind succession stages of tropical forest type in Xishuangbanna；The soil physical-chemical properties of three kind main dominant ants species in the four sites were compared, and its influences on soil CO2 release were also examined. The contributions of ants to soil CO2 emissions were also distinguished by a field excluded experiment with the method of static box-gas chromatography；The effect of microorganism change influenced by ants activities on soil CO2 emissions was studied by the combination method of Biology micro tablet and indoor cultivation method, and the respirations of bacteria and fungi were distinguished through inhibitor used method；The method of ants added indoor culture text was used to understand the ant effects on soil CO2 emissions and soil carbon mineralization. The study can reveal the influence mechanism of ant activity on the dynamics of soil CO2 emission under the four different succession stages in Xishuangbanna tropical forest, which can provide helper for the national list preparation of greenhouse gases and the data supporting the government involvement in international negotiations.

西双版纳热带雨林是我国蚂蚁分布最为丰富的地区，蚂蚁筑巢及取食活动能够引起土壤理化性质、微生物多样性及呼吸、土壤碳矿化的显著改变，从而影响土壤CO2排放动态。以西双版纳不同演替阶段4种热带森林为实验样地，研究蚁丘分布格局及蚂蚁多样性对土壤CO2排放（碱液吸收法与Li6400－09的多样点测定）的影响；同时选择各样地3种蚂蚁主要优势种为研究对象：①"静态箱－气相色谱法"测定蚂蚁巢穴与非巢地土壤CO2释放，分析蚂蚁引起土壤理化性质改变对CO2排放的影响，结合"野外排除实验"确定蚂蚁对土壤CO2排放的贡献率；②"Biolog 微平板法、室内培养法"研究蚂蚁引起微生物改变对土壤CO2排放的影响，并区分土壤细菌与真菌呼吸；③"蚂蚁添加－室内培养法"研究蚂蚁对土壤碳矿化过程中CO2排放的影响；探明蚂蚁对不同演替阶段热带森林土壤CO2排放的影响机制，为温室气体国家清单编制以及政府参与国际谈判提供支撑。

土壤动物作为生态系统工程师，能够对温室气体排放产生重要影响。目前有关温室气体排放的土壤生物学机制相当模糊，特别缺乏蚂蚁对温室气体排放影响的研究，制约人们对温室气体排放机理的理解。选择我国蚂蚁多样性最丰富的中科院西双版纳热带植物园作为实验区，以热带雨林破坏形成的4种演替阶段森林群落（白背桐、野芭蕉、崖豆藤及高檐蒲桃）为研究样地，运用“野外原位测定、宏基因组高通量测序、需氧培养法及微生物抑制法”等方法，研究蚂蚁筑巢引起土壤理化性质、微生物多样性、细菌与真菌呼吸、碳矿化的改变，及这些变化对土壤CO2排放影响的机制。. 结果表明: (1) 不同演替阶段热带森林蚁丘分布格局及蚂蚁多样性对土壤CO2排放具有显著影响。穴居蚂蚁种类总数、总密度、蚁巢密度、盖度、Shannon多样性对土壤CO2排放的贡献率分别达89%、61%、90%、75%和81%；(2) 蚂蚁筑巢显著改变土壤微生物量碳、理化性质及C/N库形成，进而对土壤CO2排放产生显著影响。蚂蚁筑巢提高土壤温度（9-26%）与水分（33-78%）、降低容量（14-39%）与pH（6.8-8.2%）；提高微生物碳（58-110%）、有机质（42-103%）及易氧化碳（33-78%）；提高全氮（23-114%）、水解氮（48-126%）、氨氮（58-133%）及硝氮（65-140%），3种蚂蚁巢地CO2排放量(1.14 g C m−2h−1) 显著高于非巢地(0.55 g C m−2h−1) ；(3) 蚂蚁筑巢显著改变碳矿化速率（17-26%），进而显著影响矿化过程中CO2排放（28-67%）；(4) 蚂蚁筑巢改变微生物结构及多样性，进而显著影响CO2排放。不同森林微生物群落组成类似，但菌群丰度在样地间及蚂蚁种类间存在差异。总体上巢中微生物丰度及多样性高于非巢地，微生物多样性能解释80-94%的CO2排放量；蚂蚁筑巢提高细菌基础呼吸(89%)及基质诱导呼吸(55%)、提高真菌基础呼吸(88%)及基质诱导呼吸(98%)，样地细菌与真菌呼吸比率达2:1-4:1。. 上述结果量化了蚂蚁筑巢对“微生物量碳、微生物多样性、理化性质、C/N库格局、C矿化、细菌与真菌呼吸、土壤CO2排放”的具体贡献，能为理解土壤动物在热带森林CO2排放中的作用与机制，以及为温室气体国家清单编制及缓解全球变化提供理论与数据支撑。