舟山海岛主要造林树种幼苗的光合特性

【目的】比较舟山海岛主要造林树种对光的适应性和耐阴性,探讨树种在海岛植被恢复过程中的配置依据。【方法】使用Li-6400便携式光合仪对普陀樟(Cinnamomum japonicum var. chenii)、舟山新木姜子(Neolitsea sericea)、红楠(Machilus thunbergii)、全缘冬青(Ilex integra)、滨柃(Eurya emarginata)、柃木(Eurya japonica)和厚叶石斑木(Raphiolepis umbellate)等7个树种幼苗叶片的光合日进程、光响应过程等进行测定,并对其光合特性和耐阴性进行比较分析。【结果】红楠净光合速率(P_n)日变化趋势呈双峰型,其他6个树种呈现单峰型,厚叶石斑木P_n显著高于其他树种(P<0.5),普陀樟P_n显著低于其他树种(P<0.5); 7个树种的气孔导度(G_s)与蒸腾速率(T_r)日变化趋势与P_n变化趋势相似,胞间CO₂浓度(C_i)日变化趋势与P_n变化趋势相反; 在光响应过程测定中,7个树种的P_n都随着光合有效辐射(PAR)的增强而增大,达到一定值后不同树种间的表现略有不同; 滨柃的光饱和点(LSP)最高,厚叶石斑木光补偿点(LCP)最高,普陀樟的光饱和点和光补偿点都最低; 对光饱和点和光补偿点进行聚类分析表明,滨柃属于强阳性树种,厚叶石斑木、全缘冬青、柃木、舟山新木姜子为阳性树种; 红楠、普陀樟为耐阴性树种。【结论】在舟山海岛植被恢复过程中,滨柃、厚叶石斑木应配置在全光环境下,全缘冬青、柃木应配置在疏林或灌丛下,红楠、普陀樟、舟山新木姜子应配置在弱光环境中。

Photosynthetic characters of seedlings of plant species for afforestation in Zhoushan Island

Abstract: 【Objective】Compare the light adaptation and shade tolerance of plant species for afforestation on Zhoushan Island, Zhejiang Province, to provide development bases for plant species in the island vegetative recovery process. 【Methods】The diurnal changes of photosynthesis and light response characteristics for Cinnamomum japonicum var. chenii, Neolitsea sericea, Machilus thunbergii, Ilex integra, Eurya emarginata, Eurya japonica, and Rhaphiolepis umbellata were measured using the Li-6400 portable photosynthesis system. Then, the photosynthetic characters and shade tolerance of seven plant species were compared. 【Results】The diurnal changes in net photosynthetic rate(P_n)of M. thunbergii presented a double-peak curve pattern, others presented a single-peak curve pattern. P_n of R. umbellate was significantly higher and the P_n of C. japonicum was significantly lower than that of the others. The diurnal changes in stomatal conductance(G_s)and transpiration rate(T_r)of the seven species was similar to the diurnal changes in P_n, and the diurnal changes in intercellular CO₂ concentration(C_i)was opposite to that of P_n. In the light-photosynthetic response determination, P_n of the seven species increased with enhanced photosynthetically active radiation, and when it reached a certain threshold varied among the seven species. E. emarginata had the highest light saturation point(LSP), and R. umbellate had the highest light compensation point(LCP), whereas C. japonicum had the lowest LSP and LCP. The cluster analysis for LSP and LCP showed that E. emarginata belonged to the strong positive species, R. umbellate, I. integra, E. japonica and N. sericea were positive species. The remaining three species were classified as shade-tolerant tree species. 【Conclusion】Our results indicated that E. emarginata and R. umbellate should be configured in full-light environments on the island during the vegetative recovery process. I. integra and E. japonica should be placed under the open forest or in thickets, whereas the other three species should be in a weak-light environment.