Study On Leaf And Fine Root Functional Characters And Fine Root Dynamics Of Pinus Dabeshanensis C.Y.Cheng&Y.W.Law

Pinus dabeshanensis belongs to Pinus of Pinaceae.The natural distribution area is is increasingly narrow,and now it has become a first-class endangered plant in China.Many scholars have carried out research on Pinus dabeshanensis,ranging from macroecological conservation to stoichiometric characteristics and preliminary studies on the morphological structure of fine roots.However,few researchers have combined the functional traits of aboveground and belowground parts of Pinus dabeshanensis,as well as fine root turnover dynamics and seedling cultivation..In this study,we collected leaf and fine root samples from three forest types and soil samples from three forest types of plantation,semi-natural forest,natural forest and cultivated seedlings in Miaodao forest Farm,Yuexi County,Anhui Province.The functional traits of leaves and fine roots,and their relationships with soil nutrients were measured.The changes of fine root biomass in different soil layers and seasons were compared.The seasonal variation and turnover rate of fine root biomass of Pinus dabeshanensis in different habitats were measured.In addition,different concentrations of nitrogen were added to Pinus dabeshanensis seedlings during the growing season,and seedling growth was analyzed.The main findings of this study are as follows:(1)The largest variation coefficient of leaf functional traits was specific leaf area,while the smallest variation coefficient was organic carbon.There were no significant differences in leaf water content and dry mass,but there were significant differences in leaf surface area and leaf organic carbon content.Soil water content,soil organic carbon content,and total phosphorus content were the main soil factors affecting the needle functional traits of Pinus dabeshanensis.Fine root tissue density and specific surface area were significantly positively correlated with soil total nitrogen,while fine root specific root length and specific surface area were significantly negatively correlated with soil total phosphorus.Therefore,a reasonable soil nutrient ratio would be beneficial to the growth of fine roots of Pinus dabeshanensis.(2)The fine roots of Pinus dabeshanensis in artificial forest,semi-natural forest and natural forest were mainly distributed in shallow soil layer.The biomass of fine roots decreased with the deepening of soil layer.The fine root biomass was affected by temperature.There was a significant positive correlation between fine root biomass and soil C content in three habitats.There was a significant correlation between fine root biomass and soil N content in the semi-natural forest.Due to loose soil and high contents of organic carbon(C),total nitrogen(N),and total phosphorus(P)in the shallow soil layer,fine root biomass was large.The turnover rates of the plantation,semi-natural forest,and natural forest were 0.69,0.62,and 0.64 times a year,respectively,indicating that artificial fertilization could promote the turnover of fine roots of Pinus dabeshanensis.(3)Different nitrogen concentrations had no significant effect on the base diameter of Pinus dabeshanensis seedlings,while seedling height under low nitrogen addition was significantly higher than that under other treatments.There was a significant positive correlation between needle dry mass and leaf surface area.Leaf thickness was significantly positively correlated with leaf biomass and leaf surface area.The biomass of seedlings was the highest under low nitrogen concentration treatment,and the nutrient element content in leaves was higher than that in roots and stems.Low N fertilization promoted seedling growth,while high N addition inhibited seedling growth and development.