Spatial-temporal Variation Of Stoichiometric Characteristics Of Picea Asperata Seedlings During Regeneration And Its Environmental Interpretation

In order to understand the physiological adaptation mechanism during seedling regeneration,Picea Asperata,a typical dominant species of cold-temperate coniferous secondary forest in North China,was taken as the research object to study the changes of regeneration seedlings with age and elevation in this study.The main research contents are as follows:(1)The changes of leaf morphological characteristics and C,N,P stoichiometric characteristics with age and elevation of Picea Asperata seedlings,and the correlation between leaf morphological characteristics and C,N,P stoichiometric characteristics were analyzed to study the effects of C,N,P stoichiometric characteristics on leaf morphology;(2)Changes of root morphological characteristics and C,N,P stoichiometric characteristics with age and altitude of Picea Asperata seedlings,and correlation analysis of root morphological characteristics and C,N,P stoichiometric characteristics were conducted to study the effects of C,N,P stoichiometric characteristics on root morphology;(3)Changes of soil C,N,P stoichiometric characteristics with altitude were analyzed.(4)To study the correlation between C,N and P stoichiometric characteristics of Picea Asperata seedlings' leaves-roots-soils,and to study the nutrient sources during Picea Asperata seedling development.The purpose of this study is to understand the spatial and temporal variations of C,N and P in the process of spruce Picea Asperata regeneration under leaf morphological characteristics changes,and to provide an important supplement for further revealing the ecological mechanism of Picea Asperata regeneration,and to provide a theoretical basis for the establishment of approaches and methods for forest vegetation restoration and biodiversity maintenance in this area.The main conclusions are as follows:(1)With the increase of age class,the leaf length,width,perimeter and area of Picea Asperata seedlings increased,the specific leaf area decreased,the leaf C,P content and C:N value increased,the leaf N content,C:P and N:P value decreased,the activity of Rubisco enzymes increased;the average diameter,specific root length and specific surface area of roots increased,the contents of C,N and P in roots increased,and the values of C:P and N:P in young seedings roots were increasing first and then decreasing.From the changes of leaf and root morphological indices and their corresponding carbon,nitrogen and phosphorus contents and Rubisco enzyme activity,it was found that seedlings showed the characteristics of allometry with the age of development.(2)With the increase of altitude,the variation of leaf morphology and stoichiometric characteristics with altitude was consistent with that with age,Rubisco enzyme activity increased,root mean diameter,specific root length and specific surface area decreased,root C,N,P content increased and N:P value decreased.From the changes of leaf and root morphological indices and corresponding carbon,nitrogen and phosphorus content and Rubisco enzyme activity,it was found that seedling regeneration was greatly affected by environmental factors related to altitude change.(3)With the change of altitude,soil C,N,P and root C,N,P were significantly positively correlated,root and soil C,P content was significantly positively correlated with leaf C,P content,and significantly negatively correlated with leaf N content;leaf Rubisco enzyme activity was significantly positively correlated with leaf C,P content,and significantly negatively correlated with leaf N content.The contentt of C,N and P in leaves is influenced by the measurement of C,N and P in roots and soils,and is closely related to the photosynthesis regulated by Rubisco enzyme activity.The content of C,N and P in soil can explain the change of C,N,P content in Picea Asperata seedling leaves.The Rubisco enzyme activity in Picea Asperata seedling leaves over 5 years explained the content of C,N in leaves more than soil.(4)The leaf and root morphology of Picea Asperata seedlings were significantly correlated with their carbon,nitrogen and phosphorus content(ratios)with age and altitude.The growth of Picea Asperata seedlings is influenced by C,N and P at elemental level.C,N and P in leaves and roots play a regulatory role in the process of seedling renewal by affecting the morphological characteristics of leaves and roots.