Abstract: 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.

Key words: karst, calcium content in plant, calcium content in soil, adaptation to high calcium