元谋干热河谷沟蚀地区植被恢复对土壤养分和酶活性的影响

Effect of Vegetation Restoration on Soil Nutrients and Enzyme Activities in the Gully Eroded Areas of Yuanmou Dry-hot Valley

为了解元谋干热河谷沟蚀地带植被恢复初期土壤养分含量及土壤酶活性的变化,在植被恢复区与未恢复区(裸地)设置样方,对土壤养分含量和酶活性进行了研究。结果表明:(1)植被恢复前后,土壤理化性质与土壤酶活性差异显著,恢复区的土壤碳(C)、氮(N)含量和土壤酸性磷酸酶(AP)、β-D-葡糖苷酶(BG)、β-1,4-N-乙酰氨基葡糖苷酶(NAG)、脲酶(URE)活性显著高于未恢复区(侵蚀裸地);但单位C含量下的土壤酶活性变化不显著,表明土壤C积累是土壤酶活性变化的关键影响因子。(2)土壤酶活性化学计量特征变化显著。相比于未恢复区,恢复区的土壤C:N酶活性比(BG∶NAG)显著下降,N∶P酶活性比(NAG∶AP)显著增加,说明N元素限制增大、C元素限制缓解,P元素不是主要限制因子。(3)土壤酶活性与土壤碳氮含量显著相关。土壤酶活性、NAG∶AP与土壤TN、TC、TP及C∶N、C∶P和N∶P呈显著正相关,而BG∶NAG则与这些因素呈显著负相关,表明养分含量变化是引起植被恢复前后土壤酶活性及其化学计量特征变化的主导因子。

The changes of soil nutrient contents and enzyme activities were studied in the gully erosion area of Yuanmou Dry-hot valley at the early stage of vegetation restoration.The results showed that:(1)In the process of vegetation restoration,there were significant differences in soil physical and chemical properties and enzyme activities.The contents of soil total carbon(TC)and total nitrogen(TN),and soil enzyme activities(acid phosphatase,AP;β-1,4-glucosidase,BG;β-N-acetylglucosaminidase,NAG;Urease,URE)in the restoration area were significantly higher than those in the eroded bare land.The results showed that soil C was a key influencing factor for the changes in soil enzyme activities during vegetation restoration.(2)The stoichiometric characteristics of soil enzyme activities changed significantly.The ratio of BG to NAG(BG∶NAG)was decreased significantly,while that of NAG to AP(NAG∶AP)was increased significantly,indicating that N-limitation was increased and C-limitation was relieved.Phosphorus(P)was not the main limiting factor for the changes in enzyme activities.(3)Soil enzyme activities were significantly correlated with soil physicochemical properties.Soil enzyme activities and NAG∶AP were positively correlated with soil total TN,TC,Total P,ratios of C to N,C to P and N to P,while BG:NAG was negatively correlated with these factors,indicating that nutrients were the leading factors that cause the changes in soil enzyme activities and their stoichiometric characteristics during vegetation restoration.