摘要:研究了林分密度和外源性氮（N）磷（P）添加及二者的交互作用对土壤酶活性的影响，可以为当前不同密度的亚热带林在氮沉降和施磷肥条件下，影响我国亚热带人工林土壤养分转化的酶学机制提供理论依据。以大叶相思（Acacia auriculiformis）人工林为试验材料，选择氯化铵（NH₄Cl）和二水合磷酸二氢钠（NaH₂PO₄·2H₂O）作为N肥和P肥，氮磷添加设置4个处理，即对照、施N、施P和施N+P；种植密度设置低密度（1667株/hm²）、中密度（2500株/hm²）、较高密度（4444株/hm²）和高密度（10000株/hm²）4个水平。在4种密度的大叶相思人工林下各设置一个样地（即4个样地），每个样地内5个样方，每个样方内设置4种处理，合计共16个处理，5个重复，80个小区，测定土壤脲酶、磷酸酶和过氧化氢酶活性，分析林分密度和NP添加对大叶相思林地土壤酶活性的影响。研究结果表明：N添加对各林分密度下的土壤脲酶和过氧化氢酶活性均有抑制作用，P添加显著提高了过氧化氢酶活性和高密度林分大叶相思林地的土壤脲酶活性，却降低了低密度林分的土壤脲酶活性；土壤磷酸酶活性在P和N+P添加两种处理下显著小于对照和施N处理；土壤脲酶、磷酸酶以及对照和P添加处理下的过氧化氢酶活性均随着林分密度的升高呈现上升趋势，而土壤过氧化氢酶活性在N和N+P添加后随着林分密度的减小而升高。林分密度和外源性NP添加的交互作用对三种土壤酶的活性均有显著影响。



Abstract:In this paper, the effects of planting density, N and P additions, and the both interaction on soil enzyme activity were studied in Acacia auriculiformis stands, which is helpful to provide theoretical basis for the enzyme mechanism affecting soil nutrient transformation under different planting densities, N deposition, and P fertilizer application background in subtropical forests. NH₄Cl and NaH₂PO₄·2H₂O were selected as N and P fertilizers, respectively. Four fertility treatments (control, N, P, and N+P) were used in four density A. auriculiformis stands (low density with 1667 trees/hm², medium density with 2500 trees/hm², relatively high density with 4444 trees/hm², and high density with 10000 trees/hm²). The four fertility treatments were used in 5 small plots of each density A. auriculiformis stand, which formed a total of 16 treatments with 5 repetitions for each treatment. The results showed that the soil urease activity and catalase activity increased in the A. auriculiformis stands after N addition. P addition significantly increased the soil urease activity under high density stand, but reduced urease activity under low density stand compared to that of the control treatment. The activity of soil phosphoric enzyme under N and N+P treatments was significantly smaller than the control and N treatment. The soil urease and phosphoric enzyme activities increased with increasing forest density, while soil catalase activity increased with decreasing stand density under N and N+P treatments, but reduced under the control and P treatment. The interactive effects of different stand densities and N and P additions on the soil catalase, urease and phosphoric enzyme activities were significant in the A. auriculiformis stands.





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