黄土高原弃耕地自然恢复过程中微生物碳的大小和活性的动态

耕地弃耕后植被次生演替过程中土壤微生物碳的大小和活性的研究结果表明，与耕地相比，各种演替阶段的弃耕地均有较高的有机碳和微生物碳含量，在26 a限弃耕地中，有机碳和微生物碳的含量达到天然植被的64.56%和48.69%，而且有机碳和微生物碳与演替的时间表现为显著正相关（P<0.01），而微生物碳和有机碳的比值却随着演替没有显示明显的变化趋势。有机碳和微生物碳的大小顺序为：自然植被>各种演替阶段的弃耕地>小麦地。代谢熵（qCO2）随着演替的进程没有明显的变化趋势。与各种弃耕地和耕地相比，自然植被有较低的qCO2。这说明耕地弃耕后植被的自然演替有利于提高土壤微生物碳，改善土壤肥力。

Size and Activity of Microbial Biomass in Vegetation Restoration of Abandoned Arable Land in Central Region of Loess Plateau, China

We have determined the Microbial Biomass Carbon(MBC),organic Carbon(OC),and basal respiration during succession of abandoned arable land in the central region of Loess Plateau.The results showed that compared with wheat plot there was an increased trend in the content of OC and MBC at various fallows.Furthermore,the succession duration was markedly correlated with the content of OC(P<0.01),MBC(P<0.05).However,the ratio of MBC/OC showed no clear tendency during succession.Overall,OC,MBC concentrations in soil ranked as follows: natural grassland>various fallows>wheat plot.The metabolic quotient(qCO_(2)) gradually declined with succession,and showed a negative correlation with succession age(P<0.01),and a negative relationship with OC,and MBC.Natural grassland had a lower metabolic quotient compared with different fallows and wheat plot.Therefore,the results suggested that vegetation secondary succession after arable land abandoned may improve degraded soil chemical and microbial properties in the central region of Loess Plateau.