春季解冻过程对2种温带森林土壤微生物量碳氮和可溶性有机碳氮的影响

为了研究春季土壤冻融过程对碳氮周转的影响,以长白山地区2种森林土壤为研究对象,利用原位培养连续取样法,测定和分析了土壤微生物量碳(MC)、氮(MN)和可溶性有机碳(DOC)、氮(DON)在春季解冻期间的含量动态变化。结果表明:土壤解冻过程中,2种林型土壤微生物量碳、氮的时间变化动态不同,且土壤微生物量碳、氮表现出明显的垂直空间异质性,0—10cm土层土壤微生物量氮显著高于10—20cm土层。除个别时期外,0—10cm土层土壤微生物量碳亦显著高于10—20cm土层土壤。解冻过程中,2种林型0—10cm土层土壤DOC含量时间变化动态基本一致,而红松阔叶林10—20cm土层土壤最大DOC释放量早于次生白桦林。2种林型DOC释放过程集中于解冻中后期。解冻期2种林型土壤DON时间变化动态表现一致,最大土壤DON释放量出现在解冻中后期。解冻期2种林型土壤DON存在明显的垂直空间分布特征,0—10cm土层土壤DON含量显著高于10—20cm土层。

Effects of Spring Thawing Process on Soil Microbial Biomass Carbon and Nitrogen and Soluble Organic Carbon and Nitrogen in Two Temperate Forests

In order to study the effects of soil freezing and thawing process on carbon and nitrogen turnover in spring, the contents of microbial biomass carbon (MC), microbial biomass nitrogen (MN), soluble organic carbon (DOC) and nitrogen (DON) in two kinds of forest soil in Changbai Mountain area during spring thawing were measured and analyzed through continuous sampling in situ culture. The results showed that: during the soil thawing process, the temporal variations of MC and MN were different in the two types of soil, moreover the MC and MN showed obvious vertical spatial heterogeneity, and MN content in 0 - 10 cm soil layer was significantly higher than that in 10 - 20 cm soil layer. Except for individual periods, MC content in 0 - 10 cm soil layer was also significantly higher than that in 10 - 20 cm soil layer. During thawing process, the DOC content dynamics in 0 - 10 cm soil layers were basically the same in two types of soil, but the maximum DOC release in 10 - 20 cm soil layer presented earlier in Korean pine broad-leaved forest than that in Secondary birch forest. The DOC releases of the two forest types were both concentrated in the middle and late stages of thawing. During the thawing period, the temporal dynamic changes of DON in two forest types were consistent, and the maximum DON release occurred in the late stage of thawing. There were obvious vertical spatial distribution characteristics for DON content in two forest types during thawing period, and the content of DON in 0 - 10 cm soil layer was significantly higher than that in 10 - 20 cm layer.