衡阳紫色土丘陵坡地不同恢复阶段土壤基础呼吸及代谢熵的变化

Changes in SBR and qCO2 at Different Re-vegetation Stages on Slopingland with Purple Soils in Hengyang of Hunan Province, South-central China

摘要:

为探讨衡阳紫色土丘陵坡地不同植被恢复阶段中的土壤呼吸特征,采用空间序列代替时间序列的方法,对土壤基础呼吸(SBR)及代谢熵(qCO₂)的变化进行了研究,并分析了它们与土壤性质的关系。结果表明:不同植被恢复阶段中的SBR、qCO₂ 存在明显差异,从裸地(Ⅰ)、草本群落(Ⅱ)、灌木群落(Ⅲ)到乔木群落(Ⅳ)阶段,SBR 显著增强(P<0.05),qCO₂ 显著减小(P<0.05)。每个恢复阶段,土层深度从0~20 cm、20~40 cm 到40~60 cm,SBR 显著减弱(P<0.05),qCO₂ 显著增加(P<0.05)。从Ⅱ、Ⅲ至Ⅳ阶段,根际(R)与非根际(S)的SBR 显著增加(P<0.05),SBR 的R/S 显著减小(P<0.05);而qCO₂ 逐渐减小(P>0.05),qCO₂ 的R/S 逐渐上升(P>0.05),SBR 与qCO₂ 均表现出R > S 的特点。相关分析表明,SBR 与土壤微生物量碳(SMBC)、土壤温度(SST) 呈极显著正相关(P<0.01),与土壤容重(SBD)呈显著负相关(P<0.05);qCO₂ 与SMBC 呈极显著负相关(P<0.01),与ST呈显著负相关(P<0.05),与SBD和pH值呈显著正相关(P<0.05)。这些对于构建植被恢复技术体系具有理论与实践意义。

Abstract:

In order to understand the changes in soil respiration of sloping-land with purple soils in Hengyang, the soil basal respiration (SBR), metabolic quotient (qCO₂) were studied by using the space series to replace time series, and the relationships between SBR, qCO₂ and soil properties were analyzed. The results showed that SBR and qCO₂ had significant difference at different re-vegetation stages. From bare land stage (Ⅰ), herb community stage (Ⅱ), shrub community stage (Ⅲ) to tree community stage (Ⅳ), SBR significantly increased (P<0.05), while qCO₂ significantly decreased (P<0.05). At every re-vegetation stage, SBR significantly decreased (P<0.05) along 0-20 cm, 20-40 cm, and 40-60 cm soil layers, while qCO₂ significantly increased (P<0.05). From Ⅱ, Ⅲ to Ⅳ stages, SBR of rhizosphere (R) and non-rhizosphere (S) significantly increased (P<0.05), and R/S of SBR significantly decreased (P<0.05), while qCO₂ of R and S gradually decreased (P>0.05), and R/S of qCO₂ gradually increased (P>0.05). SBR and qCO₂ in rhizosphere were bigger than those in non-rhizosphere. Correlation analysis showed that SBR had significantly positive correlation with soil microbial biomass carbon (SMBC) and soil temperature (ST) (P<0.01), and significantly negative with soil bulk density (SBD) (P<0.05). qCO₂ had significantly negative correlation with SMBC (P<0.01) and ST (P<0.05), but significantly positive with SBD and pH value (P<0.05). These would have a theoretical and practical significance for building vegetation restoration technique system.