喀斯特季节性雨林优势树种叶片微形态与光合生理特征及其生态适应性

Leaf micromorphological, photosynthetic physiological characteristics and their ecological adaptability of dominant -tree species in a karst seasonal rain forest in Guangxi,China

关键词:  喀斯特， 季节性雨林， 生境异质性， 叶片微形态， 光合生理特征， 生态适应

Key words:  karst, seasonal rain forest, habitat heterogeneity, leaf micromorphology, photosynthetic physiological characteristics, ecological adaptation.

摘要:

为深入理解喀斯特季节性雨林优势树种对异质性生境条件的适应策略，该研究以广西弄岗原生性森林7个优势树种为对象，测定各树种成年个体叶片微形态结构及生长季光合生理特征等指标，探讨树种叶片结构功能对喀斯特峰丛山地异质性生境的响应规律。结果表明：（1）沿喀斯特地貌部位的洼地-中坡-山顶生境梯度，树木的叶片紧密度、栅栏组织厚度、角质层厚度、上表皮厚度等9个微形态指标均呈显著上升趋势，叶片疏松度呈显著下降趋势。（2）沿洼地-中坡-山顶生境梯度，树木的光补偿点、暗呼吸速率、最大蒸腾速率等均呈显著上升趋势，最大水分利用效率、最大胞间CO2浓度、表观量子效率等均呈显著下降趋势。（3）叶片紧密度与光合能力、蒸腾能力等相关指标则表现为显著正相关，叶片疏松度与这两类指标则表现为显著负相关。综上认为，喀斯特季节性雨林优势树种叶片功能性状存在光合效率和耐旱性之间的权衡，洼地生长的树木具有显著的弱光适应特征，中坡生长的树木表现较广的生境适应范围，山顶分布的树种因受强光、高温和裸岩限制而表现出较强的干旱适应特征以及保守的生态适应策略。

Abstract:

In order to study the adaptive strategies of dominant tree species in a karst seasonal rain forest to heterogeneous habitat conditions, seven dominant tree species in a virgin forest in Nonggang, China, were taken as the research objects. The leaf micromorphological physiological characteristics of adult individuals of each tree species and the photosynthetic indexes of leaves in the growing season of these trees were measured, and the response of leaf structure and function of tree species to heterogeneous habitat in karst peak-cluster mountain was discussed. The results were as follows: (1) Along the karst habitat gradient from valley to hilltop, nine leaf micromorphological indexes, such as leaf compactness, palisade tissue thickness, cuticle thickness, and epicuticle thickness, showed a significant upward trend, while leaf looseness showed a significant downward trend. (2) Along the karst habitat gradient from valley to hilltop, the light compensation points, dark respiration rate, and maximum transpiration rates of these leaves all showed a significant upward trend. However, the maximum water use efficiency, the maximum intercellular CO2 concentration, and the apparent quantum efficiency showed a significant downward trend. (3) Leaf compactness was positively correlated with photosynthetic and transpiration ability indexes. Leaf looseness was negatively correlated with these two types of indexes. In conclusion, there is a trade off relationship between photosynthetic efficiency and drought tolerance in leaf functional traits of dominant tree species in the karst seasonal rain forest. Trees distributed in the valley have obvious adaptive characteristics to weak light. Trees distributed on the slope show extensive habitat adaptability. Due to the limitation of strong light, high temperature and exposed rock, the trees distributed on the hilltop show strong drought adaptability and conservative ecological adaptive strategies. 