不同植被下碳酸盐岩石发育形成土壤属性研究

为探究喀斯特地区不同植被条件下碳酸盐岩石发育土壤属性的分布特征及其影响因素，以贵阳市花溪区范围内的碳酸盐岩石（石灰岩、灰质白云岩和白云岩）发育土壤为研究对象，采集不同植被类型下0~40 cm土壤，分析不同植被类型、基岩类型、土层层次对土壤性质分布特征的影响。结果表明：基岩和植被类型是影响碳酸盐岩石发育成为土壤的主要影响因素，其次是土壤层次。在0~20 cm和20~40 cm土层中，石灰岩、灰质白云岩和白云岩发育土壤的肥力和颗粒均差异显著，而0~20 cm与20~40 cm土层间，除石灰岩发育土壤石砾含量（SLC）和细颗粒比（<0.002 mm），白云岩发育土壤速效磷（AP）和有机质（SOM）含量外，同类基岩发育土壤性质无显著差异；在0~40 cm土层，基岩类型显著影响土壤pH、AP、SLC、速效氮（AN）、全氮（TN）、SOM、0.2~0.25 mm和0.002~0.02 mm颗粒的分布；植被类型显著影响石灰岩发育土壤pH、AP、TN含量，白云岩形成土壤的pH、SLC、粗颗粒（0.25~2 mm）和细颗粒，灰质白云岩形成土壤的AN、SOM、粗颗粒和细颗粒；土壤层次显著影响石灰岩发育土壤的SLC、粗颗粒和细颗粒及白云岩发育土壤的AP的分布。研究区内荒草坡和草被下土壤，以及石灰岩发育的土壤可能正遭受侵蚀的破坏。因此，结合母岩岩性，改变植被种植结构，对提高土壤养分、改善土壤颗粒组成和增强土壤的抗侵蚀能力具有积极作用。

Soil properties of carbonate rocks under different vegetation types

Guizhou Province is located in the largest continuous karst area in the world. The karst landform accounts for 73.8% of the province's land area where 88% of its rural population live. The exposed area of carbonate rocks developed in karst reaches 130,000 km2, accounting for 73% of land area in this province. Soil erosion leads to the exposure of carbonate rocks on the surface, aggravates the process of karst rocky desertification, and causes a series of ecological and environmental problems, all of which seriously affect the development of local economy and people's life. The research on the comprehensive prevention and control of karst rocky desertification has become a scientific problem that needs to be solved urgently. In addition, bedrock and vegetation play a prominent role in soil development and formation. In different soil development stages, bedrock and vegetation types have an important impact on the soil physical and chemical properties. However, the current research on karst soils mainly focuses on the soil properties of limestone-formed soils. There is still a lack of research on the characteristics of soil developed by carbonate rock and the effects of their interactions on soil in karst areas from the perspective of vegetation-soil-bedrock system.Taking the soil developed by carbonate rock (limestone, calcareous dolomite and dolomite) as the research object, this study aims to explore the distribution characteristics and influencing factors of the soil developed by carbonate rock under different vegetation conditions in karst areas, and analyze the effects of different vegetation types, bedrock types and soil layers on soil properties. The study area is located in Huaxi district, Guiyang City, Guizhou Province. It has a subtropical monsoon climate with an average annual temperature of 14.9 ℃ and an average annual precipitation of 1,229 mm. Three representative plots in Huaxi district were selected, including Huaxi Reservoir, Huaxi TV Tower, and the area near the southern Guizhou University, and a total of 60 soil samples were collected from these three sample plots of different carbonate rock types. The main tree species in the study area are Cupressus funebris, Quercus, and Myrsine Africana, and grass species are Stipa bungeana and Cynodon dactylon. The soil physicochemical properties were determined by potentiometric method, Kjeldahl method, alkaline hydrolysis diffusion method, molybdenum antimony anti-colorimetric method (sodium bicarbonate extraction), and potassium dichromate oxidation with an external heating method. The particle size distribution of soil was determined by the hydrometer method. In SPSS24 software, Shapiro-Wilk test was used to test the normality of the data. Mann-Whitney U test and Kruskal-Wallis H test (multiple comparison, Bonferroni method) were used to test the difference of soil properties with different sampling depths, vegetation types and bedrock types. Scheirer-Ray-Hare test was used to determine whether vegetation type, bedrock type, soil layer, and their interactions had a significant effect on soil particles and fertility. Permutation multivariate analysis of variance (PERMANOVA) was used to analyze whether there were significant differences between two or three groups of data. Non-metric multi-dimensional (NMDS) was used to analyze the particle and fertility indexes of the soil developed by different bedrock types in the 0-20 and 20-40 cm soil layers. Redundancy analysis (RDA) was used to analyze the effects of vegetation type, bedrock type, and soil layer on changes in soil properties. These analyses were performed in the R version 4.0.3.The bedrock and vegetation types are the main factors affecting the development of carbonate rocks into soil, followed by soil layers. In 0-20 and 20-40 cm soil layers, the fertility and particles of the soil developed by limestone, limy dolomite and dolomite are significantly different. However, between the 0-20 and 20-40 cm soil layers, there is no significant difference in the nature of the soil developed from the same bedrock except the differences between gravel content (SLC) and fine particle ratio (<0.002 mm) of limestone-developed soil and the differences between available phosphorus (AP) and organic matter (SOM) content of dolomite-developed soil. In the 0-40 cm soil layer, the bedrock type significantly affects the distribution of soil pH, AP, SLC, AN, total nitrogen (TN), SOM, and 0.2-0.25 mm and 0.002-0.02 mm particles. Vegetation type significantly affects the pH value, AP, TN content of limestone-developed soil, pH, SLC, coarse particles (0.25-2 mm) and fine particles of dolomite-developed soil, and available nitrogen (AN), SOM, coarse and fine particles of soil developed by limestone dolomite. The soil layer significantly affects the distribution of SLC, coarse and fine particles in limestone-developed soil and AP in dolomite-developed soil.At present, the soil under the abandoned grassland slope and grass cover and the limestone-developed soil in the study area are likely being damaged by erosion. Therefore, according to the lithology of the parent rock, moderately changing the planting structure of vegetation on soil has a positive effect on improving soil nutrients and soil particle composition, and enhancing soil erosion resistance. Besides, the interaction of bedrock-vegetation-soil system and human activities should be comprehensively considered in the prevention and control of soil erosion in karst areas.