喀斯特高原不同石漠化程度土壤C、N、P化学计量特征和酶活性的关系

Relationship between Soil C, N, P Stoichiometric Characteristics and Enzyme Activity in Karst Plateau Soils with Different Degree of Rocky Desertification

探究岩溶区不同石漠化程度土壤环境因子与土壤酶活性的关系对石漠化区的生态恢复具有重要意义。以云南省石林彝族自治县鹿阜镇为研究区,探究了4种石漠化程度(潜在石漠化、轻度石漠化、中度石漠化、重度石漠化)土壤碳、氮、磷养分计量特征及6个土壤酶活性(淀粉酶、脲酶、酸性磷酸酶、β-葡萄糖苷酶、脱氢酶和FDA水解酶)随石漠化程度的变化特征及其相关性,并分析了环境因子对土壤酶活性的影响。结果表明,研究区不同石漠化程度土壤有机碳、全氮含量变化特征为重度>轻度>潜在>中度,全磷含量变化特征为重度>中度>潜在>轻度;C꞉N为潜在、轻度石漠化土壤高于中度、重度石漠化土壤,C꞉P、N꞉P变化特征为轻度>潜在>重度>中度。有机碳、全氮、全磷含量均为重度石漠化土壤最高;C꞉N、C꞉P、N꞉P为潜在石漠化、轻度石漠化土壤最高。不同土壤酶活性在不同石漠化程度中变化特征不一致,其中,重度石漠化土壤脲酶、脱氢酶活性最高;中度石漠化土壤淀粉酶、脲酶活性最低,酸性磷酸酶活性最高;轻度石漠化土壤酸性磷酸酶活性最低。冗余分析及相关性分析表明,土壤有机碳、全氮与酸性磷酸酶活性呈负相关关系,与其他酶活性均呈正相关关系;TP与淀粉酶、FDA水解酶呈负相关,与其他酶活性呈正相关;C꞉N、C꞉P、N꞉P与淀粉酶活性呈极显著正相关关系,与酸性磷酸酶、β-葡萄糖苷酶活性呈负相关关系。冗余分析显示土壤因子对土壤酶活性变异影响大小排序为:全氮>有机碳>pH>全磷>C꞉N>N꞉P>C꞉P,其中全氮解释了64.4%的土壤酶活性变异。结合碳氮磷生态化学计量和土壤酶活性特征,该研究表明,全氮是影响喀斯特高原石漠化区土壤质量的主要限制因子。

It is of great significance for ecological restoration to explore the relationship between soil environmental factors and soil enzyme activities in karst rocky desertification area. The study area is located at Lufu Town, Shilin Yi Autonomous County, Yunnan Province. The soil carbon (C), nitrogen (N) and phosphorus (P) stoichiometry and six soil activities (amylase, urease, acid phosphatase, β-glucosidase, dehydrogenase and fluorescein diacetate hydrolase) were investigated in sites with four rocky desertification levels (potential, mild, moderate and severe rocky desertification). And the relationships between C, N, P stoichiometry and enzyme activities as well as the influential factors were analysed. The results showed that, the contents of soil organic carbon and total nitrogen in different rocky desertification area ordered as severe>mild>potential>moderate desertification site, while for total phosphorus content: severe>moderate>potential>mild. The soil C/N ratio at potential and mild rocky desertification sites was higher than that at moderate and severe rocky desertification sites. The ratios of soil C/P, N/P were mild>potential>severe>moderate site. The contents of organic carbon, total nitrogen and total phosphorus were the highest in severe rocky desertification site. However, the stoichiometry of C/N, C/P, N/P in the potentialand mild rock desertification area was the highest. The activities of the different soil enzymes were not consistently varied in the different stony sites. Among which, the dehydrogenase activity was the highest in the heavy rocky site. The amylase and urease activities were the lowest while the activity of acid phosphatase was the highest in moderate rocky desertification site, and the acid phosphatase activity in mild rocky area was the lowest. Redundancy analysis and correlation analysis showed that soil organic carbon and total nitrogen were negatively correlated with acid phosphatase activity and positively correlated with other enzyme activities. TP was negatively correlated with amylase and FDA hydrolase, and positively correlated with other enzyme activities. The ratios of C/N, C/P, N/P were positively correlated with amylase activity, but negatively correlated with acid phosphatase and β-glucosidase activity. Redundancy analysis showed that the effect of soil factors on soil enzyme activity variation was ranked as follows: total nitrogen>organic carbon>pH>total phosphorus>C/N>N/P>C/P, total nitrogen accounted for 64.4% of the variation in soil enzyme activity. Combined with the characteristics of carbon, nitrogen and phosphorus ecological stoichiometry and soil enzyme activity, this study shows that total nitrogen is the main limiting factor affecting soil quality in rocky desertification area of karst plateau.