基于Farquhar改进模型的北亚热带森林常见树种光合限速因子研究

Limiting States of Photosynthesis of Common Tree Species in the North-subtropical Forest Based on Improved Farquhar Model

摘要:

为探讨北亚热带地区植物的光合限速因子，利用改进的Farquhar模型研究了9种常见树种的光合特性。结果表明，与常绿树种相比，落叶树种枫香（Liquidambar formosana）和乌桕（Sapium sebiferum）的最大净光合速率（P_max）和表观羧化速率（CE）较大；核酮糖-1，5-二磷酸羧化酶/加氧酶（Rubisco）活性是他们的光合限速因子。地带性树种青冈栎（Cyclobalanopsis glauca）的P_max和CE在常绿木本植物中最大，青冈较强的光合能力可能是来源于V_cmax和TPU。耐阴灌木八角金盘（Fatsia japonica）和美人茶（Camellia uraku）的P_max较小，其光合限速因子是叶肉细胞导度和呼吸速率。低光照下植物较低的光合能力是由于较小的叶肉导度（g_m）和TPU导致的；有效光合辐射短时间的降低使得物种的g_m平均减少了60.14%。因此，不同树种在不同环境条件下的光合限速因子不尽相同，应根据树种不同的光合生理特性来合理布局，科学育林。

Abstract:

In order to understand the limiting factors of photosynthesis of tree species in north-subtropical forest, China, the photosynthesis characteristics of nine common tree species was studied by using improved Farquhar model. The results showed that the maximum photosynthesis rate (P_max) and carboxylation efficiency (CE) of deciduous Liquidambar formosana and Sapium sebiferum were higher than those of other evergreen species; the activity of ribulose bisphosphate carboxylase oxygenase (Rubisco) was limiting factor of photosynthesis rate in two species. The CE and P_max of Cyclobalanopsis glauca were the highest among seven evergreen species, and its strong photosynthesis capacity might derive from high maximum carboxylation rate (V_cmax) and triose phosphate utilization rate (TPU). The P_max of shade-tolerant shrub Fatsia japonica and Camellia uraku was low because of low g_m and high dark respiration rate (R_d). The low photosynthesis capacity under low light intensity (200 μmol m^-2s^-1) was due to low g_m and TPU. The reduction of effective photosynthetic radiation in short term caused g_m decrease by 60.14%. Therefore, the photosynthetic limiting factors of different tree species were different under different environment conditions. It was necessary for reasonable arrangement of tree species and scientific afforestation according to its photosynthetic characteristics.