喀斯特地区植物钙含量特征与高钙适应方式分析

 喀斯特地区土壤的高钙含量是影响该地区植物生理特征的最重要环境因素之一。高钙影响植物的光合作用、生长速率及磷代谢, 从而限制了许多物种在该地区的分布。选取贵州4个石漠化程度不同的地区, 测定采集地内45种优势种或常见种的地上部分和地下部分的全钙含量以及土壤的交换性钙含量。通过分析喀斯特地区植物与土壤钙含量的特征发现: 喀斯特地区植物具有较高的钙含量平均值; 土壤交换性钙含量对植物地上部分钙含量的影响总体上不显著, 对植物地下部分钙含量的影响显著; 不同类别植物的钙含量存在显著差异, 蕨类植物地上部分钙含量平均值明显低于被子植物; 不同类别植物钙的分布部位也存在显著差异, 在蕨类植物和单子叶植物中地上部分和地下部分的钙含量相近, 而双子叶植物的地上部分钙含量明显高于地下部分。分析了喀斯特地区14种优势灌木和草本植物地上部分与地下部分钙含量的差异性以及与土壤交换性钙含量的相关关系, 以此为根据将14种优势植物对土壤高钙的适应方式分为3种类型: 随遇型、高钙型和低钙型。随遇型植物的钙含量主要受土壤交换性钙含量影响, 其地上部分和地下部分的钙含量均与土壤交换性钙含量成显著正相关关系; 高钙型植物具有较强的钙富集能力, 其地上部分即使在低钙含量的土壤中也可维持较高的钙含量; 低钙型植物的地上部分即使在高钙含量的土壤中亦可维持较低的钙含量。对植物适应钙的不同方式的研究可用于筛选退化生态系统恢复所需的植物资源。

CALCIUM CONTENTS AND HIGH CALCIUM ADAPTATION OF PLANTS IN KARST AREAS OF CHINA

Aims High soil calcium is an important factor influencing physiological characteristics of plants in karst areas. It causes harmful effects on plants by inhibition of photosynthesis, growth and phosphorus metabolism, thus limiting the number of species inhabiting karst areas. Our objective is to analyze plant calcium contents and different adaptation mechanisms to high calcium environment in karst areas to provide basic information on selection of plants useful for ecological restoration in karst areas. Methods We collected a total of 45 dominant or common plant species and corresponding soil sam-ples in four karst areas (Puding, Huajiang, Libo and Luodian) in Guizhou Province and measured total calcium contents in aboveground and underground plant parts along with the exchangeable calcium con-tents in soils. We analyzed the relationship between plant calcium and soil exchangeable calcium for 14 of the dominant shrubs and grasses by Pearson’s correlation and the calcium content difference by ANOVA. Important findings Average calcium content of vegetation was very high. The exchangeable calcium content in soil was significantly related to calcium content of plant underground parts but not above-ground parts. There were significant differences among plant groups. Average calcium contents in aboveground parts of ferns were much lower than that of angiosperms. Calcium contents in above-ground parts were similar to that in underground parts in ferns and monocotyledons, but were much higher than that in underground parts in dicotyledons. In addition, we classified three categories of plant adaptation to high calcium environment in karst areas: calcium-indifferent, high-calcium and low-calcium. For calcium-indifferent species, the exchangeable calcium content in soil was the key fac-tor influencing the calcium contents, and the calcium content in plant aboveground and underground parts had a significant positive correlation with exchangeable calcium content in soil. For high-calcium species, the calcium contents in aboveground parts were always high, even in soil with low exchange-able calcium content. In contrast, the calcium contents in aboveground parts of low-calcium species was always low, even in soil with high exchangeable calcium content.