去除外生菌根对红壤侵蚀区马尾松人工林土壤酶活性的影响

Effects of Ectomycorrhizal Exclusion on Soil Enzyme Activities in Pinus massoniana Plantation in Red Soil Erosion Area

马尾松作为南方红壤侵蚀区植被恢复重要的先锋树种,其与外生菌根之间的共生关系是马尾松应对环境胁迫的重要环节,但外生菌根真菌如何影响马尾松林土壤碳和养分循环尚不清楚。本研究以红壤侵蚀区恢复18年的马尾松林为研究对象,通过壕沟法设置对照和隔离菌根处理,研究了外生菌根对土壤碳、氮有效性和碳氮磷相关酶活性的影响。结果表明:去除菌根显著降低了土壤NH_(4)^(+)含量(P<0.05),显著提高了土壤可溶性有机碳(DOC)和NO_(3)^(-)含量(P<0.05);去除菌根后酸性磷酸酶活性显著提高了31.7%,而β-葡萄糖苷酶活性、β-N-乙酰氨基葡萄苷酶以及纤维素水解酶活性分别显著下降35.5%、49.0%、43.5%。上述结果表明去除外生菌根会减缓碳的循环、增加土壤氮的损失风险、加剧土壤微生物和植被对磷的需求。因此,红壤侵蚀区马尾松林外生菌根真菌发挥着加速有机质循环、提高养分保持和供给的作用,对侵蚀退化地土壤养分及关键酶活性具有重要的影响。

Pinus massoniana is an important pioneer tree species for vegetation restoration in red soil erosion areas of south China.The symbiotic relationship between masson pine and ectomycorrhizal fungi is an important link in the response to environmental stress.However,how ectomycorrhizal fungi affects soil carbon and nutrient cycling in masson pine forest is still unclear.In this study,an 18-year-old masson pine forest restored in the red soil erosion area was used.The control and isolation ectomycorrhizal treatments were set by the trench method to study effects of ectomycorrhizal on soil carbon,nitrogen availability and carbon,nitrogen and phosphorus related enzyme activities.The results showed that the ectomycorrhizal exclusion significantly reduced the soil NH_(4)^(+) content(P<0.05),and significantly increased the soil dissolved organic carbon(DOC)and NO_(3)^(-) content(P<0.05).The acid phosphatase activity was significantly increased by 31.7%,whileβ-glucosidase activity,β-N-acetylglucosaminidase and cellulose hydrolase activities were significantly reduced by 35.5%,49.0%,and 43.5%,respectively,after ectomycorrhizal exclusion.This indicated that the ectomycorrhizal exclusion will slow down the carbon cycle,increase the risk of soil nitrogen loss,as well as the demand for phosphorus by soil microorganisms and plants.Therefore,the ectomycorrhizal fungi of the masson pine forest in the red soil erosion area plays a role in accelerating the cycle of organic matter,improving the maintenance and supply of nutrients,thus has an important impact on the soil nutrients and key enzyme activities in the erosion degraded land.