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

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.

Key words:North-subtropical forest;Photosynthesis rate;Woody plant;Farquhar model