Study On Adaption Of Typical Plants In Karst Areas Of Southwest China

Different site conditions lead to different mechanisms of plant ecological adaptations. In this paper, comparative studies on the foliar characteristics of Vitex negundo grown in different geomorphological locations and different geological background were investigated from the angles of plant physio-chemistry and structural anatomy. Major results were obtained as follows. (1) Vitex negundo had strong ability of osmoregulation. The contents of proline and soluble proteins in the leaves of Vitex negundo had obvious seasonal characteristics. For example, the contents of proline and soluble proteins were higher in the leaves of Vitex negundo grown in limestone area of Maocun of Guilin in dry season (October), which were respectively 2.3 times and 3.35 times higher than that in rainy season. (2) The leaves of Vitex negundo grown in the karst areas had the characteristics of leaves of xerophytes. The thickness of the leaves, the epidermis of both upside and downside, and the compact degree of palisade tissue of Vitex negundo were much greater in the karst areas than that in the non-karst areas. These characteristics were helpful to decrease water transpiration, which was consistent with the field observation results of daily average transpiration rate in karst areas being lower than that in non-karst areas. Moreover, the vascular tissue of the leaves was more developed in the karst areas than that in the non-karst areas, which make it advantageous to promote water transportation and migration of nutrient elements under the condition of decrease of transpiration. (3) There were obvious differences in the morphological structure of the leaves of Vitex negundo among different geomorphological locations. Compared to the Vitex negundo grown in Slope, the Vitex negundo grown in Saddle had more thickness leaves, more bushy epidermic hairs, and more developed palisade tissue, which make it advantageous to decrease water losses so that decrease damage caused by karst drought. Above characteristics of leaves of Vitex negundo reflected the ecological adaptation to the karst drought environments. These results would provide a scientific basis on further deep exploration of adaptation mechanisms of typical plants to karst environments, and provide valuable reference foundation for choice and planting of the suitable plants, and management of rock desertification in karst areas.