杉木林下套种阔叶树对土壤生态酶活性及其化学计量比的影响

目的 研究杉木林下套种阔叶树的土壤生态酶活性及其化学计量比，评估该林分土壤养分和肥力状况。 方法 在福建省三明市格氏栲自然保护区杉木林试验示范区设置3种处理，分别是杉木成熟林套种阔叶树、杉木幼林套种阔叶树，以及不套种阔叶树的杉木纯林 (对照)，测定其表层 (0~10 cm) 土壤的理化性质、土壤微生物生物量碳氮磷含量及土壤酶活性，并计算酶化学计量比。 结果 杉木林下套种阔叶树后,尤其是杉木成熟林套种阔叶树，土壤全碳 (TC)、全氮 (TN)、微生物生物量碳 (MBC) 含量增加。套种处理之后，土壤β-N-乙酰氨基葡萄糖苷酶 (NAG) 和酸性磷酸酶 (AP) 酶活性显著升高，β-葡萄糖苷酶 (βG) 酶活性显著降低；βG: AP和NAG: AP的平均值分别为0.006 4和0.011 3，远低于全球平均水平，表明该区域土壤微生物受磷限制，AP酶和NAG酶的活性提高，使得βG: AP和βG: NAG值在套种处理之后显著降低。冗余分析表明土壤C: N和MBC: MBN分别解释土壤酶活性和生态酶化学计量比变异的92.3%和4.4%。 结论 杉木套种阔叶树有助于土壤养分积累，改良土壤性状。

Effects of Chinese Fir Interplanted with Broadleaved Trees on Soil Ecological Enzyme Activity and Stoichiometry

Objective To study the soil enzyme activities and their stoichiometry in Chinese fir (Cunninghamia lanceolata) forests interplanted with broadleaved trees, and assess the soil nutrient and fertility conditions in these forests. Method Soil physicochemical properties, soil microbial biomass carbon (MBC), nitrogen (MBN) and phosphorus (MBP), and soil enzyme activities in surface soil (0~10 cm in depth) were determined in different interplanting forests (young Chinese fir interplanting forest, mature Chinese fir interplanting forest) and pure Chinese fir plantation in Sanming, Fujian Province. Result The contents of total C, total N and MBC increased significantly after interplanted with broadleaved trees, especially in mature Chinese fir interplanting forest. After interplanting, the activities of: β-N-Acetylglucosaminidase (NAG) and acid phosphatase (AP) increased significantly, and the activity ofβ-glucosidase (βG) decreased significantly. The ratios of βG:AP and NAG:AP were lower than global average, which showed that the soil microorganisms in this area were in the state of phosphorus restriction. The activities of AP and NAG increased after interplanting and thus βG:AP and βG:NAG ratios decreased significantly. Redundancy analysis showed that soil C:N and MBC:MBN explained 92.3% and 4.4% of soil enzyme activity and enzyme stoichiometric ratio variation, respectively. Conclusion Chinese fir interplanted with broadleaved trees can help to accumulate soil nutrients and improve soil properties.