西南喀斯特土地利用变化对植物凋落物-土壤C、N、P化学计量特征和土壤酶活性的影响

以贵州关岭花江喀斯特峡谷原生林、灌木林、草地和坡耕地这4种典型土地利用方式下的凋落物-土壤为研究对象,研究土地利用变化对西南喀斯特植物凋落物-土壤C、N、P化学计量特征和土壤酶活性的影响及其驱动机制.结果表明,4种不同土地利用方式的凋落物-土壤C、N、P含量和土壤酶活性存在显著差异.与其他区域相比,凋落物和土壤分别具有高C低N高P、低C低N高P的格局.脲酶、蔗糖酶和淀粉酶表现出原生林灌木林草地坡耕地,碱性磷酸酶则是原生林灌木林坡耕地草地.未来的生态建设应重视原生林的保护.土壤养分受凋落物C、N、P及其计量比的显著影响,但土壤酶活性与凋落物无显著联系.冗余分析表明,土壤酶活性与土壤TN、SWC、C∶N极显著相关(P 0. 01),与p H和N∶P显著相关(P 0. 05),重要性大小依次为TN SWC C∶N p H N∶P.

Influence of Land Use Change on Litter and Soil C, N, P Stoichiometric Characteristics and Soil Enzyme Activity in Karst Ecosystem, Southwest China

In this study, the litter and soil under four typical land use patterns of primary forest, shrub, grassland, and sloping land in Huajiang Karst Gorge in Guanling, Guizhou Province, were used to study the effects of land use change on the carbon(C), nitrogen(N), and phosphorus(P) stoichiometry characteristics of karst plant litter and soil as well as the effects on soil enzyme activities and their driving mechanism in Southwest China. The results showed significant differences in the litter-soil C, N, and P contents and soil enzyme activities among the four land use types. Compared with other regions, the litter and soil showed a pattern of high C, low N, high P and low C, low N, high P, respectively. Urease, sucrose, and amylase showed an order of primary forest > shrub forest > grassland > slope farmland, whereas alkaline phosphatase showed primary forest > shrub forest > slope farmland > grassland. The protection of primary forests should be considered in future ecological construction. The soil nutrients were significantly affected by litter C, N, P, and their ratios, although the soil enzyme activities were not significantly associated with the litter. Redundancy analysis showed that soil enzyme activity had extremely significant correlation with the soil total N (TN), water content (SWC), and C:N ratio (P<0.01) and relatively significant correlation with pH and the N:P ratio (P<0.05). The order of importance was shown to be TN > SWC > C:N > pH > N:P. The research results have significant value for the study of karst rocky desertification and karst ecosystem nutrient cycling.