土壤置换法研究土壤基质对微生物碳氮磷的影响

【目的】探索植被演替初期不同土壤基质对微生物碳氮磷含量及其化学计量比的影响。【方法】于2004年采集天然次生林(演替前样地)的A层(淋溶层)、B层(淀积层)和C层(母质层土)土,分别填入30 cm土层厚度的样地,构成A、B和C处理,分别模拟森林皆伐次生演替、无种子库次生演替和原生演替,每种处理4个重复,经过10 a自然演替,比较不同土壤基质间微生物碳氮磷含量及其化学计量比的差异。【结果】① 演替前样地不同土壤基质微生物生物量碳氮磷及其占土壤碳氮磷的比例均呈现出A处理显著高于B、C两个处理(P < 0.05, C处理微生物生物量氮占土壤氮比例除外); 土壤微生物生物量碳氮比(n_Cmic/n_Nmic)为A处理低于B、C处理,土壤微生物生物量碳磷比(n_Cmic/n_Pmic)和微生物生物量氮磷比(n_Nmic/n_Pmic)均为A处理高于B、C处理; ② 演替后样地,不同土壤基质微生物生物量碳氮磷呈现出A处理显著高于B、C两个处理(P < 0.05),其占土壤碳氮磷的比例均呈现出A处理高于B、C两个处理; n_Cmic/n_Nmic为A、B处理低于C处理,n_Cmic/n_Pmic和n_Nmic/n_Pmic均为A处理高于B、C处理; ③ 经过10 a植被演替,A、B、C 3个处理土壤微生物生物量碳氮磷浓度及其占土壤碳氮磷的比例均上升(B处理n_Pmic除外); 3个处理n_Cmic/n_Nmic下降、n_Cmic/n_Pmic和n_Nmic/n_Pmic上升,其中,B、C两个处理的n_Cmic/n_Nmic显著下降(P < 0.05),A、C两个处理的n_Nmic/n_Pmic显著上升(P < 0.05)。【结论】植被演替初期,不同土壤基质理化性质的差异是影响土壤微生物碳氮磷的主要因素。

Effects of substrates on soil microbial carbon,nitrogen and phosphorus based on soil replacement method

【Objective】Examine the effects of soil substrates on microbial biomass carbon(n_Cmic)nitrogen(n_Nmic), and phosphorus(n_Pmic)by comparing their values in the early stage of vegetation succession. 【Method】By using the soil displacement experiment performed included three treatments. Treatment A involved replacing the original soil of experimental plots(0-30 cm depth)with the A-horizon soil of an adjacent temperate broadleaved stand, whereas Treatment B involved replacing the soil with B-horizon soil, and treatment C involved replacing the soil with C-horizon soil. The three treatments simulated the secondary succession of clear-cut forests or bare soil without a seed bank or primary succession, respectively, and four replicates were used for each treatment. This study compared the difference of the n_Cmic, n_Nmic, n_Pmic, and their stoichiometry in different soil substrate. 【Result】① In 2004, the n_Cmic, n_Nmic and n_Pmicof treatment A were significantly greater than those of treatments B or C(P < 0.05), and the n_Cmic/n_Nmic ratio of treatment A was lower than those of treatments B or C, whereas the n_Cmic/n_Pmic and n_Nmic/n_Pmic ratios of treatment A were greater than those of treatments B or C. The n_Cmic/n_Csoil(soil carbon), n_Nmic/n_Nsoil(soil nitrogen)and n_Pmic/n_Psoil(soil phosphorus)values of treatment A were significantly greater than those of treatments B or C(P < 0.05), except for the n_Nmic/n_Nsoil value of treatment C. ② In 2014, the n_Cmic, n_Nmic and n_Pmic of treatment A were significantly greater than those of treatments B or C(P < 0.05), and the n_Cmic/n_Nmic ratio of treatments A and B were lower than that of treatment C, whereas the n_Cmic/n_Pmic and n_Nmic/n_Pmic ratios of treatment A were greater than those of treatments B or C. The n_Cmic/n_Csoil, n_Nmic/n_Nsoil, and n_Pmic/n_Psoil values of treatment A were greater than those treatments B or C. ③ After the 10-year succession, the n_Cmic, n_Nmic and n_Pmic of the three treatments increased, except for the n_Pmic of treatment B. The n_Cmic/n_Nmic ratio of the three treatments declined, but the n_Cmic/n_Pmic and n_Nmic/ n_Pmic ratios increased. Among the three treatments, the n_Cmic/n_Nmic ratio of treatments B and C decreased significantly(P < 0.05), whereas the n_Nmic/n_Pmic ratio of treatments A and C increased significantly(P < 0.05). The n_Cmic/n_Csoil, n_Nmic/n_Nsoil and n_Pmic/n_Psoil values of three treatments also increased with the succession. 【Condusion】 The physical and chemical properties of the different substrates were the main determinants of the spatial patterns of n_Cmic, n_Nmic, n_Pmic, and their stoichiometry.