山核桃集约经营过程中土壤微生物量碳氮的变化

目的]研究不同集约经营历史山核桃林的土壤微生物量碳氮的演变规律,为山核桃林地土壤管理提供科学依据。方法]在浙江省临安市分别采集并分析了经营历史为5,10,15,20a的山核桃林土壤样品,并与天然混交林(0a)进行比较。结果]天然混交林改造为山核桃纯林并经集约经营后,林地土壤微生物量碳(MBC)、微生物量氮(MBN)、MBC/MBN,MBC/SOC均表现出先下降而后上升的趋势,经过10a经营后降到最低水平,与0a相比,0—10cm土层MBC,MBN和MBC/SOC分别降低了52.1%,32.0%和31.0%。经营10a的林地土壤MBC/MBN显著低于前期经营林地,而MBN/TN在经营过程中的差异并不显著。结论]山核桃集约经营后,林地土壤微生物量碳氮含量显著下降。

Changes in Soil Microbial Biomass Carbon and Nitrogen of Carya Cathayensis Plantations Under Intensive Managements

Objective] The differences of soil microbial biomass carbon(MBC) and microbial biomass nitrogen(MBN) in Carya cathayensis stands with different management intensification were explored to provide scientific basis for soil management.Methods] Soil MBC and MBN collected from four intensive-managed forests(IMF) (5, 10, 15 and 20 years, respectively) were assayed and compared with the corresponding values of natural broadleaf forest(0 year).Results] Soil MBC and MBN, MBC/MBN and MBC/SOC decreased significantly at the first 10 years after conversion from evergreen and deciduous broadleaf forest(EDBE) to intensive-managed forest(IMF), and then increased slowly. In comparison with the corresponding value of EDBF(0 year), MBC, MBN and MBC/SOC in 0-10 cm soil layer of chinese hickory forest with 10-year intensive management decreased by 52.1%,32.0% and 31.0%, respectively. These indices were also lower than those corresponding values of stands with other intensive management years. Soil MBC/MBN with 10-year intensive management was lower than the values of stand before 10-years; Soil MBN/TN remained stable under different years. Conclusion] Soil MBC and MBN of Carya cathayensis stands decreased remarkably after intensive-management was conducted.