杂草五爪金龙对其入侵地土壤酶活性与微生物群落的影响

Impacts of Invasive Weed Ipomoea cairica on the Soil Enzyme Activitiy and Microbial Community

五爪金龙是粤东地区入侵性极强的外来杂草,其对入侵地土壤生态系统可能存在明显的改造作用.在野外调查的基础上,确定3个被五爪金龙重度入侵的生境作为采样地,通过室内实验测定与分析五爪金龙对入侵地土壤酶活性、土壤微生物群落的影响.结果表明:与非入侵地比较,杂草五爪金龙种群在粤东地区的入侵明显改变了入侵地的土壤生态系统的部分结构与功能,包括显著提高了入侵地土壤中蔗糖酶、脲酶、磷酸酶及硝酸还原酶的活性,其提高幅度均在2倍以上;增加了真菌、自生固氮菌及氨氧化细菌的数量,降低了细菌与反硝化细菌的数量,其改变率均大于20%.土壤酶活性与土壤微生物群落的改变可能导致土壤肥力的变化,因此,五爪金龙成功入侵的土壤微生物学机制有待进一步探讨.

As an invasive weed with strong invasiveness in East Guangdong, Ipomoea cairica may have obvious transformation effects on the soil ecosystem in invaded habitat. On the basis of field investigation, im- pacts of I. cairica were determined and analyzed on the soil enzyme activitiy and microbial community from 3 sampling plots through laboratory experiments. The experimental results showed that the partial structure and function of soil ecosystem were significantly changed by invasive weed I. cairica in East Guangdong, in compar- ison with the control, activities of invertase, urease, phosphatase and NR were significantly enhanced, and all the improved rates were more than 2 times. The quantity of fungus, nitrogen fixing bacteria and ammonia oxidiz- ing bacteria were most abundant, but the number of bacterium and denitrifying bacteria were greatly reduced in invaded habitats, and all the change rates were more than 20%. Changes of soil enzyme activitiy and microbial community could effect on the soil fertility, thus, the soil microbe mechanism of I. cairica＇ s successful invasion will be discussed in the next experiments.