Feature Of Needle Functional Traits Of Pinus Tabuliformis And Their Response To Soil And Altitude In Qinling Mountains

Plant functional traits are functional characteristics closely related to survival,growth and development,and reproduction that have developed during the evolutionary development of plants.They can reflect the adaptation strategies of plants under different environmental conditions.In order to investigate the ecological strategy of Pinus tabuliformis on ridge,we took natural P.tabuliformis mature forest in the middle of the Qinling Mountains as the research object and P.tabuliformis non-ridge as control,and set up three 20m×20m sample squares at the ridge and non-ridge sunny slopes at elevation of1300-1600 m,1600-1900 m and 1900-2100 m,respectively.The functional traits of the needle of P.tabuliformis on ridge,their relationship with soil and the adaptive changes along the elevation gradient were described by using analysis of variance,stepwise regression analysis and correlation analysis.The results of this study can help further reveal the stability mechanism of P.tabuliformis on ridge,and provide theoretical and practical basis for sustainable management and utilization of P.tabuliformis on ridge.The following main findings were obtained from the study.(1)There is a wide range of variation in the functional trait values of needles at all leaf ages of P.tabuliformis on ridge.The greatest variation in 1-year-old needles was leaf dry matter content,the greatest variation in 2-to 3-year-old needles was leaf potassium content.P.tabuliformis on ridge focuses more on the accumulation of dry matter and grows slower than P.tabuliformis on non-ridge.(2)The degree of response of leaf functional traits to soil varied among the different needle ages of P.tabuliformis on ridge.The response of 1-year-old needle traits to changes in soil p H,bulk density,total phosphorus,available nitrogen and available phosphorus was greatest;the response of 2-year-old needle traits to changes in soil p H,bulk density,total phosphorus,water content and organic carbon;and the response of 3-year-old needle traits to changes in soil bulk density,total phosphorus,water content,available potassium and total nitrogen was greatest.(3)P.tabuliformis on ridge showed a strong elevational pattern in functional traits of needles at different leaf ages.The specific leaf area,leaf phosphorus content and leaf thickness of 1-year-old needles of P.tabuliformis on ridge increased significantly with increasing elevation,and leaf length and stomatal density decreased significantly.The specific leaf area of 2-year-old needles of P.tabuliformis on ridge increased significantly with increasing elevation,and leaf length and leaf carbon content decreased significantly.The leaf thickness of 3-year-old needles of P.tabuliformis on ridge increased significantly with increasing altitude,and leaf length,leaf dry matter content,leaf carbon content and chlorophyll content decreased significantly.In summary,the unique habitat conditions of the ridge have created a unique growth strategy for P.tabuliformis on ridge,and in the face of elevation gradients and soil changes,P.tabuliformis on ridge exhibits a diversity of adaptation strategies,making P.tabuliformis on ridge a unique community pattern widely distributed in the Qinling Forest region.