喀斯特地区植物根系分泌物酶活性对根际土酶活性和养分的影响

Effects of plant root exudates enzyme activities on rhizosphere soil enzyme activities and nutrients in karst areas

关键词:  喀斯特生态系统, 植被恢复, 根系分泌物酶活性, 土壤酶活性, 土壤养分

Key words:  karst ecosystem, vegetation restoration, root exudates enzyme activity, soil enzyme activity, soil nutrients

摘要:

为了探究喀斯特地区植物根系分泌物酶活性对根际土酶活性和养分的影响,我们测定了灌草丛、灌木林、灌乔林和乔木林4个植被恢复阶段群落水平根系分泌物和根际土的β-1,4-葡萄糖苷酶(βG)、β-N-乙酰葡萄糖苷酶(NAG)、亮氨酸氨基肽酶(LAP)和酸性磷酸酶(ACP)的活性与土壤碳氮磷的含量,并分析了它们之间的关系。结果表明:(1)根际土以及根系分泌物的4种酶活性在植被恢复后期显著高于植被恢复前期; 乔木林的根系分泌物酶活性C:P和N:P比值显著高于其他植被恢复阶段,而根际土酶活性这2个比值则正好相反。(2)相关分析显示,根系分泌物酶活性与对应的土壤酶活性呈显著正相关; 相对于根系分泌物酶活性,土壤酶活性与相关养分的相关系数值更高。另外,根际土以及根系分泌物βG、NAG和LAP酶活性与根际土有机碳(SOC)和全氮(TN)呈显著正相关,根际土以及根系分泌物ACP酶活性与根际土速效磷(AP)呈显著正相关。上述结果表明,植被恢复对根系分泌物酶和土壤酶活性的提高具有正向的作用,根系分泌物酶是土壤酶的有利补充,在碳氮磷养分循环过程中起到积极的促进作用。综上所述,调控根系分泌物分泌及其酶活性可能为喀斯特生态系统的植被恢复提供新的视角。

Abstract:

In order to explore the activities of enzymes from plant root exudates affected rhizosphere soil enzyme activities and nutrients in karst areas, the activities of β-1,4-glucosidase( βG), β-N-acetyl-glucosaminidase(NAG), leucine aminopeptidase(LAP), and acidic phosphatase(ACP)of fine root exudates and rhizosphere soils in four vegetation restoration stages, which are shrub-grassland, shrubland, shrub-arbor forest and arbor forest, were measured. And, their relationships with soil carbon(C), nitrogen(N), phosphorus(P)contents were analyzed. The results were as follows:(1)The four enzyme activities of rhizosphere soils and root exudates were significantly higher in the late stage of vegetation restoration than in the early stage of vegetation restoration. The enzyme activities C:P to N:P ratios of root exudates in arbor forest were significantly higher than those of other three stages, while the two parameters of rhizosphere soils were opposite.(2)Correlation analysis showed that the enzyme activities of root exudates were positively correlated with the corresponding soil enzyme activity. Compared with the enzyme activities of root exudates, the correlation between soil enzyme activity and related nutrients became significantly stronger. In addition, the enzyme activities of βG, NAG and LAP in rhizosphere soils and root exudates were positively correlated with soil organic carbon(SOC)and total nitrogen(TN)in rhizosphere soil, while the enzyme activities of ACP in rhizosphere soils and root exudates were positively correlated with available phosphorus(AP)in rhizosphere soil. The above results indicate that vegetation restoration has a positive effect on increasing enzyme activities of root exudates and soils. The enzymes of root exudates are the indispensable supplement for soils, and play an important role in promoting carbon, nitrogen and phosphorus nutrient cycling. To sum up, it will be that the regulation of root exudates and its enzyme activities may provide a new perspective for vegetation restoration in karst ecosystem.