胶州湾典型河口湿地土壤活性有机碳和酶活性对互花米草入侵的响应

以胶州湾洋河口湿地为研究对象,按照互花米草入侵年份(0、1、5、8年)分层采集土壤样品(0—10、10—20、20—40 cm和40—60 cm),研究土壤活性有机碳(LOC)和酶(脲酶、过氧化氢酶、碱性磷酸酶、蔗糖酶)活性的变化,分析土壤活性有机碳和酶活性及两者相关性对互花米草入侵的响应。结果表明:与光滩相比,互花米草入侵增加了表层土壤LOC含量,且随着入侵时间的延长显著增加(P0.05)。同时也改变了土壤LOC垂直分布规律,除光滩和入侵1年样地表现出沿剖面逐渐上升之外,其他样地表现为沿剖面先上升后下降趋势;互花米草入侵提高了河口湿地土壤酶活性,但并未改变酶活性随深度增加而逐渐降低的分布规律。随着入侵时间的延长4种酶活性变化趋势有所差异,过氧化氢酶和蔗糖酶活性变化趋势一致,表现为随入侵时间延长先急剧增加后逐渐减少,而碱性磷酸酶和脲酶活性随着入侵时间的延长逐渐增加。Pearson相关性分析结果显示,土壤LOC和酶活性呈显著负相关且互花米草入侵时间越长两者间相关性越低,8年后无显著相关性。

Responses of soil labile organic carbon and enzyme activity to Spartina alterniflora invasion in estuary wetland of Jiaozhou Bay

The effects of Spartina alterniflora invasion on soil labile organic carbon (LOC) and enzyme (urease, catalase, alkaline phosphatase, invertase) activities were investigated in the Yanghe estuary wetland of Jiaozhou Bay. Soil samples were collected at 0-60 cm depths in different invasion years (0, 1, 5, and 8). The responses of LOC and soil enzyme activity to Spartina alterniflora invasion, and the relationship between them, were assessed. The results showed that Spartina alterniflora invasion significantly increased LOC contents of the surface layer in comparison to that of the mudflat (P < 0.05), and the soil LOC contents increased significantly with the increase of invasion time. Meanwhile, Spartina alterniflora invasion also changed the rule of vertical dynamics of LOC contents. Sample plot LOC first showed an increasing trend, and then decreased along the soil profile except that LOC contents of the two plots increased along the entire soil profile. Spartina alterniflora invasion increased the soil enzyme activities, but it did not change their distribution rule, as they decreased with increasing soil depth. The variation trend of 4 types of enzyme activities changed with the increase of Spartina alterniflora invasion time. The catalase and invertase activities first showed a dramatic increase and then a gradual decrease, but alkaline phosphatase and urease activities gradually increased with the increase in invasion time. Pearson correlation analysis showed that soil labile organic carbon was significantly negatively correlated with enzyme activity, and the correlation decreased with the increase of invasion time; it disappeared after 8 years.