Nonstructural Carbohydrates And Nutrient Element Conce Ntrations Of Quercus Variabilis Of Different Latitude

Plant's physiological response to geographic distribution has always been the focus of ecology research.So far,the study of plant distribution are concentrated on the differences of plant physiological characteristics and nutrients distribution in plants with altitudinal gradient,and the similar study in a latitudinal gradient is needed.Non-structural carbohydrates(NSC)concentration and nutrient content play important role in plant altitudinal distribution,while its variation with latitude gradient is still unclear.Plant physiological metabolism differs in growing season and non-growing season,different growth stages,different organs,and this difference is worth exploring in plant's response to environment.Quercus variabilis distributed in a wide range,which is thought to be one of the ideal species for studying plant's physiological response to geographic distribution.Thus,we used Q.variabilis as the study tree species,sampled its leaf,stem,bark and root of both adult tree and juvenile tree in growing season and non-growing season,then measured the NSC concentration and nutrient content.In this study,we sampled from north to south,the sample sites are as following: Beijing Pinggu(BJPG),Hebei Lincheng(HBLC),Henan Jiyuan(HNJY),Henan Neixiang(HNNX),Hubei Zigui(HBZG),Hunan Cili(HNCL)and Hunan Chengbu(HNCB)totally 7 latitude sites,collected the sample and measured NSC concentration and nutrient(N,P,K)content,and analyse the latitudinal trend of NSC concentration and nutrient content and its relationship with environmental factors.The main results are as following:1)NSC concentration of Q.variabilis different organs varied with latitude in growing season,and the variation was related to different growth stage,different organ type and NSC species.Leaf starch concentration of juvenile tree(P=0.035),stem soluble sugar concentration of adult tree(P<0.001),stem soluble sugar concentration of juvenile tree(P=0.007),bark starch concentration of adult tree(P<0.001),bark TNC concentration of adult tree(P=0.025),bark starch concentration of juvenile tree(P=0.012),root starch concentration of juvenile tree(P<0.001),root TNC concentration of juvenile tree(P=0.001)showed an significantly positive relationship with latitude,while stem starch concentration of adult tree(P=0.021)showed an significantly negative relationship with latitude.2)NSC concentration of Q.variabilis different organs varied with latitude in non-growing season,and the variation was related to different growth stage,different organ type and NSC species.Stem soluble sugar concentration of adult tree(P=0.01),stem soluble sugar concentration of juvenile tree(P<0.001),stem TNC concentration of juvenile tree(P=0.001),bark soluble sugar concentration of adult tree(P<0.001),bark TNC concentration of adult tree(P<0.001),bark soluble sugar concentration of juvenile tree(P<0.001),bark TNC concentration of juvenile tree(P=0.002)were significantly positively related to latitude.3)Nutrients content of Q.variabilis different organs showed relationships with latitude in growing season,and the relationships differed in different growth stage,different organ type and nutrient.Leaf N content of adult tree(P<0.001),stem N content of adult tree(P=0.020),stem P content of adult tree(P=0.010),root N content of adult tree(P=0.001),root N content of juvenile tree(P=0.002)were significantly positively related to latitude,while leaf P content of adult tree(P=0.045),leaf N content of juvenile tree(P<0.001),root P content of adult tree(P<0.001),root K content of adult tree(P=0.018),root P content of juvenile tree(P=0.030),root K content of juvenile tree(P=0.010)were significantly negatively related to latitude.4)Nutrient contents of Q.variabilis different organs in non-growing season varied with latitude.Stem P content of adult tree(P=0.017),root N content of juvenile tree(P=0.004)were significantly positively related to latitude,while stem K content of juvenile tree(P=0.016),bark K content of adult tree(P=0.019),bark K content of juvenile tree(P=0.002),roots K content of adult tree(P=0.013)were significantly negatively related to latitude.5)NSC concentration in different organs of adult tree in growing season showed stronger relationships with soil factors than with meteorological factors.NSC concentration in different organs of juvenile tree in growing season showed stronger relationships with meteorological factors than with soil factors.NSC concentration in different organs of adult tree and juveniel tree in non-growing season showed stronger relationships with meteorological factors thanwith soil factors.Either in growing season or in non-growing season,nutrient content in different organs of adult tree and juvenile tree showed stronger relationship with meteorological factors than with soil factors.