Analysis of Carbon Sequestration, Oxygen Release and Leaf Stomatal Micromorphology of Nine Precious Broad-leaved Tree Species

To screen for tree species with high carbon sequestration efficiency,nine common broad-leaved precious tree species in Fujian Province were selected as research objects.Photosynthetic physiological parameters and leaf stomatal micromorphological characteristics were systematically measured,daily net assimilation,daily net carbon fixation,and daily oxygen release were calculated,and comprehensive evaluation was conducted using correlation analysis and hierarchical cluster analysis.The results showed that the net photosynthetic rate(P_n)of the nine tree species ranged from 5.15 to 6.51 μmol·m^-2·s^-1,and daily net carbon fixation ranged from 7.25 to 9.04 g·m^-2·d^-1.Among them,Schima superba exhibited the highest value,while Camphora officinarum showed the lowest,with a 1.25-fold difference between them.Five tree species,including Castanopsis hystrix,Schima superba,Quercus pachyloma,Phoebe bournei and Camphora officinarum exhibited photosynthetic midday depression,whereas four tree species,including Michelia macclurei,Castanopsis carlesii,Manglietia yuyuanensis and Toona fargesii did not.Correlation analysis indicated that daily carbon fixation was significantly positively correlated with net photosynthetic rate,stomatal length,and width(P<0.05),but negatively correlated with stomatal density(P<0.05).Hierarchical cluster analysis divided the nine tree species into two groups:group I comprised Schima superba,Castanopsis hystrix,Michelia macclurei and Castanopsis carlesii,with relatively strong carbon fixation capacity;group II comprised Phoebe bournei,Quercus pachyloma,Manglietia yuyuanensis,Camphora officinarum and Toona fargesii,with relatively weak carbon fixation capacity.This study demonstrates that Schima superba,Castanopsis hystrix,Michelia macclureiand Castanopsis carlesii exhibit superior photosynthetic efficiency and daily carbon fixation and oxygen release performance,and are recommended as preferred species for high carbon sequestration forest construction in Fujian Province.In contrast,Phoebe bournei,Quercus pachyloma,Manglietia yuyuanensis,Camphora officinarum and Toona fargesii have relatively weaker carbon sequestration capacity,and their deployment should be tailored to local site conditions.These findings provide a theoretical reference for tree species selection in efficient carbon sequestration forest construction in Fujian Province.