中文摘要：

钙是岩溶环境的主要构成元素，是决定岩溶生态系统的结构和功能的关键要素之一。为研究岩溶区土壤有机碳和pH值与钙形态分布的关系，在桂林丫吉岩溶试验场以3个月为周期共2年的时间采集自然植被土壤，利用BCR方法对钙形态进行了研究，结果表明：① 岩溶区各形态钙中以酸溶态钙含量最多，占土壤全钙的61.63%，表明岩溶区石灰土中钙活跃的迁移状态和生物作用，钙在石灰土中具有较高的活度。并且各形态钙的大小顺序为酸溶态＞可还原态＞残渣态＞可氧化态；② 除可氧化态钙与土壤有机碳的相关性不显著外，各形态的钙与土壤有机碳之间均呈极显著正相关的关系（P〈001）；与土壤有机碳类似，除可氧化态钙与pH值呈不显著的负相关关系外，其余土壤钙形态与pH值均呈极显著正相关关系（P〈001）。③ 利用冗余分析可以对各形态钙与有机碳和pH值的关系大小进行排序，各形态钙与有机碳和pH的关系大小顺序均为：可还原态钙〉酸溶态钙〉残渣态钙＞可氧化态钙。研究结果有助于更清晰的了解钙在岩溶生态系统中的分布和运动特征，为深入理解岩溶区钙循环提供基础数据。

英文摘要：

Objectives： Calcium is a major component of the karst environment and is one of the key elements in determining the structure and function of karst ecosystems. The relationship between soil organic carbon and pH and calcium species in the karst area is unclear. Methods： The natural vegetation soil was collected at a period of three months in Guilin Yaji karst test site for two years. The calcium species was studied by Bureau Communautaire de Référence （BCR） method. Results： The results showed that： （1） the content of extractable calcium is the highest, with an average of 61.63% of total calcium content. It shows that calcium in limestone soil has active migration, biological action, and high activity. The order of the contents of calcium species from many to less is extractable calcium （61.63%）, reducible calcium （19.68%）, residual calcium （13.92%） and oxidizable calcium（OCa） （4.77%）. （2） There was a significant positive correlation between the calcium species and soil organic carbon （P 〈0.01） , except that the correlation between oxidizable calcium and soil organic carbon was not significant （P〉0.05）. And the relationship between pH value and calcium species was similar to that of soil organic carbon. （3） The relationship between calcium and organic carbon and pH was sorted by Redundancy Analysis （RDA）. The order of relationship between calcium and organic carbon and pH was as follows： reducible calcium〉extractable calcium〉 residual calcium〉 oxidizable calcium. Conclusions： The results of the study will help us to understand the distribution and movement characteristics of calcium in karst ecosystem, and provide the basic data for deep understanding of calcium cycle in karst area.