The Study On The Leaf Nutrients And Morphological Traits Of Psammophyte In Northern China

At present,the desertification is one of the most important environmental problems in the world.It not only changes the composition and distribution of vegetation and threatens the existence and development of local people,but also affects the development and ecological security of the region subjected to desertification.The desertified regions with the co-limiting of water and nutrients,mainly distribute in north of China.These regions,covering 27.4%of total area of China,are characterized by higher temperature,evaporation and more extreme rainfall.These characteristics have seriously affected the distribution,survival and development,as well as reproduction of psammophyte for a long time.Thus,the study on the adaptive mechanisms of psammophyte in sandy regions has important significance to desertification prevention,control and resource utilization.Focused on the psammophyte in sandy regions in north of China,the physical and chemical properties of psammophyte were analyzed along rainfall gradient in order to address the following questions:(1)what are the leaf N,P traits and leaf morphological traits across all plant species and different life forms in psammophyte,northern China;(2)what are the relationships between leaf morphological traits,leaf nutrients,as well as leaf morphological traits and leaf nutrients in sandy environment;(3)whether and how the leaf morphological traits and leaf N,P concentrations response to rainfall gradient;(4)what are the main factors influencing the leaf nutrients.The results are as follows:(1)At overall level,the average values of leaf N and P concentrations were 32.55 mg g^-1,2.94mg g^-1,respectively.And the average value of N:P was 11.58 in psammophyte.In addition,the means of LDMC,SLA,LT,LWC were 0.26 g g^-1,12.76 m²kg^-1,0.47 mm,3.76%,respectively.Compared with previous studies,the higher leaf N and P content,lower N:P and SLA were found in psammophyte.(2)Compared with herb and tree groups,the shrub group had relatively higher leaf N,P concentrations and SLA.The tree group had greatest value of LDMC,while the herb group had smallest value of LDMC.(3)Leaf N concentration was positively associated with leaf P concentration across all species and within each life form.Furthermore,leaf N:P was significantly positively related to leaf N concentration,but not correlated with leaf P concentration.(4)The significant relationship were found between SLA and LDMC.And the individual slopes had no difference among life forms,however,the slope elevation had significant variations among life forms.(5)Both leaf N and P concentrations were positively correlated with SLA,but negatively related to LDMC.However,the N:P showed no significant relationships with SLA and LDMC,respectively,across all plant species and life forms in this study.(6)The patterns of leaf nutrients and morphological traits of psammophyte varied significantly along rainfall gradient.Compared with lower rainfall regions,the higher rainfall regions tended to have higher leaf N concentration,SLA,LWC and SWC,but lower LDMC and LT.(7)The general liner model(GLM)indicated that soil total N,P concentrations and phylogeny jointly influenced leaf N:P stoichiometry,while LF had no effect on leaf N:P stoichiometry in this study.