寒温带多年冻土区不同林龄白桦林土壤酶活性动态特征

Dynamic Characteristics of Soil Enzyme Activity in Different Age Betula platyphylla Forests in The Cold Temperate Permafrost Region

为探究寒温带白桦(Betula platyphylla)次生林土壤酶活性随林龄变化的动态特征,分析土壤酶活性与环境因子的关系,选择大兴安岭北部不同林龄(30、45、66 a)白桦林为研究对象,测定土壤深度(h)为0<h≤5 cm、5 cm<h≤10 cm、10 cm<h≤20 cm、20 cm<h≤30 cm土层土壤碳、氮质量分数及磷转化酶(过氧化氢酶、蔗糖酶、脲酶、酸性磷酸酶)活性,并对其动态变化规律及影响因子进行分析。结果表明:6—10月份,3个林龄的白桦林土壤过氧化氢酶、蔗糖酶、脲酶、酸性磷酸酶活性呈单峰曲线变化趋势,变化范围分别为0.85~4.14 mL·g^(-1)、4.77~70.34 mg·g^(-1)、0.90~11.12 mg·g^(-1)、0.07~0.75 mg·g^(-1)。林龄对土壤酶活性有显著影响,林龄为30 a时,白桦林土壤酶活性较低;林龄为45 a时,白桦林土壤过氧化氢酶、蔗糖酶、酸性磷酸酶活性相对较高,林龄为66 a时,白桦林土壤脲酶活性较高。林龄为30 a的白桦林土壤过氧化氢酶及酸性磷酸酶活性在各土层均表现为7月份最高,8月份时该林龄表层(0<h≤5 cm)土壤蔗糖酶活性最高。林龄为45 a的白桦林各土层过氧化氢酶活性及表层土壤蔗糖酶、酸性磷酸酶活性均为9月份最高。林龄为66 a的白桦林表层土壤过氧化氢酶、脲酶、酸性磷酸酶活性均为8月份最高,而其他土层在该林龄时这3种酶活性的变化规律差异较大。微生物生物量碳是驱动林龄为30 a的白桦林土壤酶活性变化的主要因子,土壤含水率及可溶性有机碳对林龄为45 a的白桦林土壤酶活性影响较大,林龄为66 a的白桦林土壤酶活性主要影响因子则是硝态氮。林龄对白桦林土壤酶活性影响显著,过氧化氢酶、蔗糖酶、酸性磷酸酶活性随林龄增加呈先增后降的变化趋势,脲酶活性则随林龄增加而增加。

To explore the dynamic characteristics of soil enzyme activity in secondary forests of Betula platyphylla in the cold-temperate zone with forest age,and analyze the relationship between soil enzyme activity and environmental factors,different-aged(30,45,66 years) B.platyphylla forests in the northern part of the Daxing'anling Mountains were selected as the research objects.The soil carbon and nitrogen content and phosphorus transformation enzyme(catalase,sucrase,urease,acid phosphatase) activity measured in soil layers with soil depths of 0<h≤5 cm,5 cm<h≤10 cm,10 cm<h≤20 cm,and 20 cm<h≤30 cm.The dynamic change patterns and influencing factors were analyzed.The results showed that from June to October,the activities of catalase,sucrase,urease,and acid phosphatase in the soil of the three-aged B.platyphylla forests showed the trend of single-peak curves,with ranges of 0.85-4.14 mL·g~(-1),4.77-70.34 mg·g~(-1),0.90-11.12 mg·g~(-1),and 0.07-0.75 mg·g~(-1),respectively.Forest age had a significant impact on soil enzyme activity.In the 30-year-old B.platyphylla forest,the soil enzyme activity was relatively low.In the 45-year-old forest,the activities of catalase,sucrase,and acid phosphatase in the soil were relatively high.In the 66-year-old forest,soil urease activity was higher.In the 30-year-old B.platyphylla forest,the activities of catalase and acid phosphatase in the soil were highest in July,and the activity of sucrase in the surface soil(0<h≤5 cm) was highest in August.In the 45-year-old B.platyphylla forest,the activities of catalase in all soil layers and the activities of sucrase and acid phosphatase in the surface soil were highest in September.In the 66-year-old B.platyphylla forest,the activities of catalase,urease,and acid phosphatase in the surface soil were highest in August,while the patterns of these three enzyme activities in other soil layers varied greatly in this forest age.Microbial biomass carbon was the main factor driving the changes in soil enzyme activity in the 30-year-old B.platyphylla forest,while soil moisture content and soluble organic carbon had a greater impact on soil enzyme activity in the 45-year-old B.platyphylla forest.Nitrate nitrogen was the main influencing factor for soil enzyme activity in the 66-year-old B.platyphylla forest.Forest age had a significant impact on soil enzyme activity of B.platyphylla,with catalase,sucrase,and acid phosphatase activities showing an increasing trend followed by a decrease with increasing forest age,while urease activity increased with forest age.