不同林龄马尾松人工林土壤酶活性及其生态化学计量特征

Soil enzyme activity and its eco-stoichiometric characteristics in different aged stands of Pinus massoniana plantations

以广西南宁市横县镇龙林场的4种林龄(幼龄林、中龄林、成熟林和过熟林)马尾松人工林作为研究对象,分析了土壤不同深度(0~10、10~20和20~30 cm)的酶(β-葡萄糖苷酶(βG)、β-乙酰葡糖胺糖苷酶(NAG)、酸性磷酸酶(ACP)和碱性磷酸酶(ALP))活性的生态化学计量特征以及土壤有机碳(SOC)、全N(TN)、全P(TP)和有效P(AP)含量。研究结果显示:(1)马尾松人工林4种龄林的土壤SOC、TN和AP含量随着土壤深度增加逐渐降低;在同一土壤层时,TN含量随着林龄的增长逐渐降低,TP含量在幼龄林时最低、中龄林时最高,AP含量在幼龄林最高。(2)土壤βG、NAG、ALP和ACP酶活性在中龄林最高、在成熟林最低,且随着土壤深度的增加而降低。(3)土壤酶活性C∶N值均低于全球平均值(1.41),酶活性C∶P值和酶活性N∶P值均高于全球平均值(0.62和0.44)。(4)RDA结果显示土壤酶活性及其生态化学计量比值的变化主要受到TP和TN含量的影响。结果表明,马尾松人工林的生长受到P养分的限制,在幼龄林和中龄林的受限制程度更为严重。

Four aged stands(young forest,middle-aged forest,mature forest,and overmature forest)of plantations were selected in Zhenlong Forest Farm from Hengxian of Nanning in Guangxi were selected.The activities of four enzymes(β-glucosidase(βG),β-acetylglucosamine glucosidase(NAG),acid phosphatase(ACP)and alkaline phosphatase(ALP))and the contents of soil organic carbon(SOC),total N(TN),total P(TP),and available P(AP)in different soil depths(0-10,10-20 and 20-30 cm)were measured.There were four findings.(1)The results showed that soil SOC,TN and AP in four aged forests of Pinus massoniana plantations decreased with the increasing soil depths.Additionally,in the same soil depth,soil TN decreased with the advancing ages stand,soil TP was lowest in young forest and was highest in middle-age forest,and soil AP was highest in young forest.(2)The activities of soilβG,NAG,ALP and ACP enzyme were highest in middleaged forest and lowest in mature forest,and decreased with increasing soil depth.(3)The C∶N ratio of soil enzyme activity was lower than global average value(1.41),while C∶P and N∶P ratio of enzyme activity were higher than global average velue(0.62 and 0.44).(4)RDA results showed that the changes in soil enzyme activity and its eco-stoichiometric ratio were mainly affected by TP and TN contents.The stuydy indicated that Pinus massoniana plantations were limited by P,especially in young and middle-aged forests in this region.