Implications of the Ecophysiological Adaptation of Plants on Tropical Karst Habitats for the Ecological Restoration of Desertified Rocky Lands in Southern China

Abstract

Karst lands are widely spread in China, particularly in Southwest China, which cover the largest continuous karst area with a unique landscape. Due to the human interference for a long time and the special substrate and hot and humid climate, the karst lands in this region have been severely degraded, the desertified rocky karst lands now totally cover the area of 1.2×105 km2 in southern China. This results in environmental deterioration and difficulty for the social and economical development. Karst lands in southern China are characterized with thin or little soil, low soil nutrients and low water holding capacity. We have done a series of research on the ecophysiological adaption of plants on a tropical karst mountain. In this article, we briefly synthesize our research and the key findings, and also some other research in order to provide reference information for the ecological restoration of desertified karst lands. Our studies have indicated that the co-existence of evergreen and deciduous trees and lianas is helpful for the maintenance of water balance of karst ecosystems. The evergreen trees are tolerant to water deficit and xylem cavitation, while deciduous trees shed leaves to reduce water use in the dry season. Most of karst woody plants have deep roots, while the lianas have the deepest roots in order to reach deeper water source belowground in dry season. Some plants such as Bombax ceiba Linn. and Caryota urens Linn. store water in their stems to support the necessary physiological processes in dry season. Most of the tropical karst plants are short of Zn and K nutrients according to the foliar nutrient analysis, this should be taken into account during the ecological restoration and agricultural practices. Lianas are able to use the localized water and nutrients and employ the abundant light source and spaces of desertified karst lands by means of their climbing stems. They often have high photosynthesis and strong regulation of water use, and are useful plant materials for the restoration of the desertified karst lands. An important oil liana, Plukenetia volubilis L, is now recommended for plantation by the Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, which is an ideal plant for the restoration of desertified karst lands. The ecological restoration of desertified karst lands could consider using different function groups of plants to construct a multiple-storey community.