中国南方喀斯特石漠化演替过程中土壤理化性质的响应

Abstract

以中国西南典型喀斯特石漠化生态系统土壤为研究对象,运用野外定点取样和实验室分析检测方法,研究不同等级石漠化环境土壤理化性质特征;运用空间代替时间方法,探讨石漠化演替过程中土壤理化性质的响应及其机制,旨在为中国西南喀斯特森林生态保护和石漠化生态系统恢复重建提供理论支撑。结果表明:1)不同等级石漠化环境土壤理化性质存在显著差异,土壤容重、毛管孔隙度、总孔隙度、田间含水量、毛管含水量、pH值、有机质、水解氮、有效磷和全钾均在不同等级石漠化环境间具有显著差异。但这些指标并不是随着石漠化程度增加而一直退化,而是一个先退化后改善的趋势;2)土壤有机质、氮素、毛管持水量、容重和孔隙度与土壤其它绝大多数理化因子具有明显的相关性,是土壤理化性质的关键因子,在改善土壤理化性质和促进养分循环方面起着关键作用;3)主成分分析也表明,土壤有机质、氮素、钾素、容重、持水状况、孔隙度等是基于土壤理化性质评价石漠化程度的关键指标。作者提出了强度石漠化环境裸岩对土壤养分的聚集效应学说和喀斯特石漠化演替过程中土壤理化性质的响应及其机制。研究结果对中国西南喀斯特森林生态保护和石漠化生态系统恢复重建具有重要的理论意义和实践指导价值。;Karst rocky desertification has been an important ecological issue hindering the economy and society development of South China Karst region, and the control of rocky desertification has been clearly listed in the national projects of economy and society development. But there are short of soil researches in karst rocky desertification ecosystem, and the succession of soil physical-chemical properties is still unclear in the process of rocky desertification, which hardly hinders the control of rocky desertification well work. <br>Based on these problems, in this study, firstly, three typical rocky desertification regions, that is, Yachi, Hongfenghu, and Huajiang of Guizhou Province, representing three different typical karst landforms of plateau mountain, plateau basin, and plateau gorge, respectively, were selected as experiment areas, and 45 sample plots with area of 20 m × 20 m, respectively, were set up for the 5 typical degrees of rocky desertification, that is, no, potential, low, middle, and high, in these three experimental areas. Then, the soil physical-chemical properties were surveyed and analyzed by the methods of chemical determination and mathematical statistics. Results show that 1) there are obvious differences of soil physical-chemical properties between different degrees of rocky desertification, specifically, bulk density, capillary porosity, total porosity, field moisture capacity, capillary moisture capacity, pH, organic matter content, hydrolysis nitrogen content, available phosphorus content, and total potassium content. But, not as expected, the soil degeneration do not always raise with the increased degree of rocky desertification. In fact, with the increased degree of rocky desertification, the soil degenerate firstly and then improve; 2) Organic matter content, nitrogen content, capillary moisture capacity, bulk density, and porosity all are remarkable correlation with other factors of soil physical-chemical properties, and they are the key factors of soil physical-chemical properties, which have important functions in advancing the soil nutrient cycle and improving the soil physical-chemical properties; 3) Principal component analysis also show that organic matter content, nitrogen content, potassium content, bulk density, moisture capacity, and porosity are the key factors in evaluating the degrees of rocky desertification. Based on these results, the theory, that is, bare rocks have a collected action for soil nutrients in karst rocky desertification ecosystem, was raised, and the response and its mechanism of soil physical-chemical properties to rocky desertification succession was presented. Results have important values in the protection of karst forest ecosystem and the control of rocky desertification.