Research On Photosynthetic Characteristics Of Larix Principis-rupprechtii Plantation In Taiyue Mountain Of Shanxi Province

In order to understand the photosynthetic physiological mechanism,the spatial variation of photosynthesis and the response to the disturbance,Li-6400 portable photosynthesis apparatus was used to study the plantation of Larix principis-rupprechtii of Taiyue Mountain area in hanxi Province.Firstly,Canopy difference of photosynthetic physiological characteristics of Larix principis-rupprechtii Secondly,Response of Photosynthetic Characteristics of Larix principis-rupprechtii to Age.Thirdly,Response of Photosynthetic Characteristics to Density Control of Larix principis-rupprechtii.The main findings are as follows:(1)photosynthetic rate(Pn)were significantly differences among the crown of upper layer,middle layer and under layer in the 18-year-old plantation,while there were no significant differences in Pn among the various orientations.There was the same true in the 40-year-old plantation.For 18-year-old larch,carboxylation efficiency(Vc),Intercellular CO2 transpiration rate(Tr)concentration(Ci),were major factors influencing Pn,while for 40-year-old larch,Vc,stomatal conductance(Gs),vapor pressure deficit(pVPD)were the main factors affecting Pn.There were no significant differences in the chlorophyll a,chlorophyll b and total chlorophyll T among the various orientations and level in the 18 and 40-year-old larch.(2)Larix principis-rupprechtii relevant light and CO2 response curves were produced the results showed that photosynthetic rate(Pn),light saturation point(PLS),light compensation point(PLC),dark respiration(Rd)were significantly differencesn in 18?26?40-year-old,Maximum net photosynthetic rate(Pmax),Apparent quantum efficiency(a)were significantly differences of 26-year-old,40-year-old and 18-year-old.while there were no significant differences in 26-year-old,40-year-old.Larix principis-rupprechtii The difference between light respiration rate(Rp),carboxylation efficiency(CE)were significantly differences of 18-year-old,26-year-old and 40-year-old while there were no significant differences in 18-year-old,26-year-old.(3)The results showed that Pn increased with the intensity of density control(control group,mild control 15%,moderate control 30%,severe regulation 50%)The Pn were significantly differences of mild control group,moderate control group,severe regulation and control group,while there were no significant differences in Pn among mild,moderate and severe density.For control group,carboxylation efficiency(Vc),stomatal conductance(Gs),Stomata]limitation(Ls)were major factors influencing Pn,For mild control group,carboxylation efficiency(Vc),Intercellular CO2 concentration(Ci),stomatal conductance(Gs),were major factors influencing Pn,For moderate control group,Instantaneous water use efficiency(cWUE)carboxylation efficiency(Vc)transpiration rate(Tr)were major factors influencing Pn,For severe regulation group,carboxylation efficiency(Vc)Intercellular CO2 were major factors influencing Pn.The seasonal variation of leaf weight of Larix principis-rupprechtii was basically the same in four different densities.the leaf weight.in the moderate control is the largest?There was no significant difference in chlorophyll a and total chlorophyll T under different density control,Chlorophyll b and chlorophyll a/b ratio There were significant between the control group,mild regulation and moderate regulation,severe regulation.