人工油松林（Pinus tabulaeformis）恢复过程中土壤微生物生物量C、N的变化特征

采用时空替代法,选取15a（PF15）、25a（PF25）、30a（PF30）的人工油松林作为样地,并选取灌丛作为参考植被,研究了植被恢复过程中土壤微生物生物量C、N以及土壤养分的变化特征,同时探讨了它们之间的相互关系。研究结果表明随着恢复的进行,土壤质量得到了改善,主要表现为有机碳、全氮、粘粒含量、土壤含水量的上升和pH值、容重的下降。土壤微生物生物量C、N分别在155.00~885.64mg/kg和33.73~237.40mg/kg的范围内变化。土壤微生物生物量C、N在植被恢复的初期显著低于灌丛,而后随着恢复的进行逐步增长。土壤微生物生物量C、N与植被恢复时间的相关性没有达到统计学上的显著水平,但是土壤微生物生物量C与土壤有机碳、全氮、全磷呈显著正相关,这表明植被恢复过程中土壤微生物生物量与土壤养分状况关系密切,植被恢复通过改善土壤养分状况间接地影响土壤微生物生物量的变化。Cmic/TOC在1.38%~4.75%的范围内变化。Cmic/TOC随着植被恢复不断下降,Cmic/TOC与植被恢复时间和土壤有机碳呈显著负相关,这表明植被恢复过程中,惰性有机质积累导致供应土壤微生物的活性有机质减少,Cmic/TOC同时受土壤有机质的数量和质量影响。

Dynamics of soil microbial biomass C, N along restoration chronosequences in pine plantations

In this paper, the chronosequence approach was adopted. Three sites were selected with pine(Pinus tabulaeformis)plantations along the restoration chronosequences (15a (PF15), 25a (PF25), 30a (PF30)), and native shrub communities (Quercus aliena var.acuteserrata, respectively, and Corylus heterophylla) were chosen as reference. The objective of this study was to investigate the dynamics of soil microbial biomass C, N, and soil physico-chemical properties along the restoration chronosequences. In addition, the correlation between soil microbial properties and physico-chemical properties were examined. The results showed that the status of soil fertility in shrub community was significantly better than in pine plantation in early restoration stage; soil physico-chemical properties were gradually improved along the restoration chronosequences including the accumulation of soil organic carbon, total nitrogen, soil clay content, soil moisture content and general declines in pH and bulk density. Soil microbial biomass C, N ranged from 155 to 885.64mg/kg, and 33.73-237.40mg/kg, respectively. Soil microbial biomass C, N declined significantly in early restoration stage compared with shrub communities, and increased with the extension of plant restoration. Although statistically significant correlations were not found between soil microbial biomass C, N and restoration chronosequences, soil microbial biomass C was positively related to soil organic carbon, total nitrogen, and total phosphorus, suggesting that soil microbial biomass was closely correlated with soil fertility and plant restoration could indirectly influence soil microbial biomass by improving soil nutrient. Cmic/TOC ranged from 1.38% to 4.75%, and declined gradually with plant restoration. Correlation analysis indicated that Cmic/TOC was negatively related to soil organic carbon and restoration chronosequences. The results suggested that changes in soil microbial biomass were related not only with the quantity, but also the quality of soil organic matter during plant restoration, and that plant restoration was critical for the improvement of soil physicochemical properties and microbial properties in pine plantations of Southwest China.