Study On Photosynthetic Characteristics Of 3 Typical Broad-leaved Forest Tree Species In Tianmu Mountain

This experiment started in October 2014,and ended in September of 2015,for a year.We used PAM-2500 chlorophyll fluorescence meter and SPAD-502 relative chlorophyll content meter measured the typical broad-leaved forest species' s(Daphniphyllum macropodum?Cyclobalanopsis myrsinifolia,Chinese hydrangea)chlorophyll fluorescence parameters and relative chlorophyll content(SPAD)in Tianmu Mount.We also carried out the correlation analysis between the actual quantum yield(Y(II))and physiological factor(SPAD),ecology factors(photosynthetically active radiation(PAR),air temperature(Ta),relative humidity(RH)),in order to understand their seasonal dynamic changes of photosynthesis and their response mechanism to environmental and physiological factors.The main findings are as follows:(1).Daphniphyllum macropodum's the actual quantum yield(Y(II)),the actual photochemical efficiency(Fv '/ Fm'),photochemical quenching(q P),potential activity(Fv / Fo),maximum photochemical efficiency(Fv / Fm)and Cyclobalanopsis myrsinifolia's Y(II),Fv / Fm all showed "V" shaped curve over time;the minimum respectively in January,December,January,December,December,July,January,December;Chinese hydrangea's Y(II),Fv '/ Fm',q P,Fv / Fo and Cyclobalanopsis myrsinifolia's Fv '/ Fm',q P substantially were "W" type,the two lowest values occured in November and August,November and July,November and July,August and November,April and July;December and July,January and July;(2).Their the apparent electron transport rate(ETR)were caught up in July,Daphniphyllum macropodum and Chinese hydrangea showed as single peak curve over time;Cyclobalanopsis myrsinifolia ‘s ETR was firstly down then up and finaly down,substantially were "inverted N" type,in December therewas a substantial decline;(3).The seasonal dynamic law of the relative chlorophyll content SPAD,Daphniphyllum macropodum and Cyclobalanopsis myrsinifolia consistented performance,both were autumn> winter> summer> spring;Chinese hydrangea the highest was fall in September,followed by the summer in August,the lowest in the spring of April;(4).With PAR,Ta,RH,SPAD correlation analysis,we got that in Spring,Daphniphyllum macropodum photosynthetic capacity was mainly affected by PAR and Ta,Cyclobalanopsis myrsinifolia mainly by RH and Ta,Chinese hydrangea was PAR,SPAD,RH the these three factors;in Summer Daphniphyllum macropodum mainly affected by PAR,SPAD,Ta,Cyclobalanopsis myrsinifolia and Chinese hydrangea were relatively large affected by the four factors;in Fall,Daphniphyllum macropodum were mainly affected by PAR,SPAD,RH these three factors,Cyclobalanopsis myrsinifolia were PAR,SPAD,Ta,Chinese hydrangea were PAR,RH;in Winter,Daphniphyllum macropodum were mainly affected by Ta,Cyclobalanopsis myrsinifolia were significantly affected by PAR,SPAD,RHThe results described above showed that,the three trees under normal conditions can have a high energy conversion efficiency of PSII,photosynthetic carbon assimilation can accumulate more energy in order to promote the efficient functioning of the accumulation of carbon assimilation and carbohydrates,When faced with stress,they all through increasied heat dissipation,closed part of the light reaction system,reduced the rate of electron delivery,to start their own light protection mechanisms.This could provide the basis for the protection,repairation,reconstruction of vegetation in Tianmu Mountain Nature Reserve,as well as on the scale carbon budget through the ecosystem and regional levels.