喀斯特季节性雨林植物叶片碳同位素组成及水分利用效率

Foliar stable carbon isotope composition and water use efficiency of plant in the Karst seasonal rain forest

研究喀斯特季节性雨林不同生境代表性树种及同一树种不同生境下叶片δ13C值及水分利用效率(WUE),丰富喀斯特季节性雨林物种生态位分化及物种共存理论,可为喀斯特地区石漠化治理树种选择及配置提供参考.结果表明:喀斯特季节性雨林树种叶片δ13C值的范围为-34.13‰^-29.69‰,平均值为(-31.40±1.19)‰,WUE的范围为9.08~58.76μmol·mol-1,均值为41.79μmol·mol-1,低于更高纬度的亚热带和暖温带森林,但高于更低纬度的热带雨林和同一纬度的非喀斯特季节性雨林;从洼地到山顶,随着干旱指数的增加,不同生境代表性树种的水分利用效率逐渐增大;同一树种δ13C值和WUE也是从洼地到山顶逐渐增高.树种水分利用效率除了与气候等因子相关外,还与植物所处生境的地质背景、水分可利用性相关.同一气候条件下,喀斯特区植物的水分利用效率要高于非喀斯特区、干旱生境植物的水分利用效率高于湿润生境,说明不同的水分利用效率是喀斯特地区植物适应不同生境、实现多物种共存的策略之一.

To enrich niche partition and species coexistence theory in karst seasonal rain forest,and provide reference for species selection and configuration for rocky desertification control,we exami-ned foliar stable carbon isotope composition(δ13C)and water use efficiency(WUE)of the representative species in different habitats and the same tree species in different habitats.The results showed that foliarδ13C value in karst seasonal rain forest ranged from-34.13‰to-29.69‰,with a mean value of(-31.40±1.19)‰.WUE ranged from 9.08-58.76μmol·mol-1,with a mean value of 41.79μmol·mol-1.Both of them were lower than subtropical and warm temperate forests at higher latitude,but higher than tropical rain forests at lower latitude and non-karst seasonal rain forests at the same latitude.The foliarδ13C value and WUE of representative species gradually increased with the increases of drought index from the depression to the top of the mountain.The foliarδ13C value and WUE of the same tree species increased with altitude.These results indicated that water use efficiency of tree species was not only related to climate factors,but also related to the geological background and water availability of the habitat.The water use efficiency of plants in karst area was higher than that in non-karst area,and was higher in dry habitat than in wet habitat under the same climatic condition.It showed that having different water use efficiencies was one of the strategies for plants in karst area to adapt to different habitats and maintain species coexistence.