紫茎泽兰与不同植物群落土壤养分及酶活性差异

摘要

We investigated soil enzymatic activities and nutrients of communities of invasive Ageratina adenophora in different degree of invasion and different plant communities (Gramineae and Dicotyledons). The correlations of soil enzymatic activities and soil nutrients were analyzed. The results showed that the invasive A. adenophora significantly increased the pools of soil N, NO3-N, NH4+-N, available K and available P, but reduced the contents of soil P and soil K compared to the non-invaded. The content of NO3-N, NH4+-N, available K in heavily invaded plant community significantly higher than gramineae and dicotyledons. It is 2.29, 2.28 and 4.01 times more than the content in the dicotyledons plants area. It is 7.73, 3.22, and 5.12 times more than the content in the gramineae plants area. The soil urease, phosphatase and protease activities in heavily invaded plant community were higher than other communities. The soil urease activities is 3.49 times in heavily area more than the content in the gramineae area, the soil phosphatase and protease activities is 1.65, 2.31 times more than the content in the dicotyledons area. At the same time,after analyzing the correlations coefficient between soil enzymatic activities and nutrients we found that there were significant positive correlations among soil enzymatic activities and soil N, NH4+-N, NO3-N and available K, but significant negative correlations with soil P. Compared to different plant communities, A. adenophora invasion can greatly alter the soil physical and chemical properties and the trade-offs of soil nutrients supply and demand, which may facilitate itself growth. The soil enzymatic activities in different communities may be important factors that led to changes of soil nutrients. A. adenophora altered the trade-offs of soil nutrients supply and demand by activating soil enzymatic activities at the soil may be an important ecological mechanism of the exotic weed A. adenophora successful invasion.%为了研究紫茎泽兰（Ageratina adenophora Sprengel）与不同植物群落土壤养分及酶活性间的差异，解析不同植物群落抵御紫茎泽兰入侵的生态机制，选取紫茎泽兰不同入侵程度（重度入侵群落、轻度入侵群落、未入侵群落）和不同功能型植物群落样地（禾本科植物群落、双子叶植物群落），测定其植物群落土壤养分和酶活性变化，并对土壤酶活性与土壤养分进行相关性分析。结果表明，紫茎泽兰入侵显著增加了土壤中全氮含量，降低了全磷、全钾含量，土壤中有效养分硝态氮、铵态氮、有效磷和速效钾含量显著增加，重度入侵群落的土壤硝态氮、铵态氮、有效磷和速效钾含量显著大于未入侵群落的，是双子叶植物群落的2.29、2.28、8.13、4.01倍，禾本科植物群落的7.73、3.22、6.91、5.12倍。紫茎泽兰入侵显著提高了入侵区植物群落土壤中脲酶、磷酸酶和蛋白酶活性，重度入侵群落土壤脲酶活性是禾本科群落的3.49倍，磷酸酶活性是双子叶群落的1.65倍，蛋白酶活性是双子叶群落的2.31倍。土壤养分含量与酶活性密切相关，土壤脲酶活性与土壤全氮、硝态氮、铵态氮、全钾和速效钾显著正相关，与全磷显著负相关；土壤磷酸酶、蛋白酶活性与土壤全氮、硝态氮、铵态氮、速效钾和有效磷显著正相关，与全磷含量显著负相关。与不同植物群落相比，紫茎泽兰能更好改变土壤养分的供求平衡，这种改变可使紫茎泽兰在入侵过程中处于优势地位，植物群落间土壤酶活性差异可能是驱动土壤养分变化的重要因子。外来入侵植物紫茎泽兰通过影响土壤酶活性来改变入侵生境土壤养分的供求平衡可能是其成功入侵的生态机制之一。