Ecological Stoichiometric Analysis Of Larix Principis-rupprechtii Plantations Of Different Stand Ages

Taking Larix principis-rupprechtii community in different stand age(11 years,25 years,35 years,and45 years)of Guandi Mountain forest area as the research object,the morphological traits and physiological character(leaf length,leaf width,leaf area,etc.),soil physical and chemical properties(moisture content,bulk density,total porosity,aeration,p H,ammonium nitrogen,nitrate nitrogen,available phosphorus)and the total nutrients of carbon,nitrogen,and phosphorus in needle leaf-leaf litter-soil continuum were measured,which was investigated through field sampling and indoor experiments.The trend with stand age of the morphological traits and physiological character,,and the physical and chemical properties of the soil under the forest,and the ecological stoichiometry of the needle leaf-leaf litter-soil C,N,P of Larix principis-rupprechtii were analyzed.The interaction relationship is summarized and the research results show that:(1)The C,N,and P contents of the needle leaf,leaf litter,and soil in the Larix principis-rupprechtii plantation in Guandi Mountain forest area were all represented as needle leaf > leaf litter > soil.The surface soil TN is more strongly affected by coniferous TN,while the shallow soil C / P,N / P is more strongly affected by coniferous C / P,N / P.(2)The functional traits of Larix principis-rupprechtii exist as an indivisible whole.With the increase of leaf water content,leaf length,leaf width,leaf area,and total nitrogen content also increased.As the stand age increases,the leaf length,leaf width,leaf area,and moisture content increase.Leaf width is more sensitive to the stand age than the leaf length.(3)The leaf litter C,N,and P contents of Larix principis-rupprechtii plantation showed a pattern of low C,high N,and P content.The C,N content,C / P,N / P of leaf litter showed a trend of rising first and then decreasing with the increase of standt age,and the change of P content with the increase of stand age showed the opposite trend;C / N of leaf litter decreased with the increase of stand age.(4)With the increase of stand age,the C and N content of the soil layer differentiation became larger,the bulk density,water content,and total porosity soil layer differentiation increased and then decreased.The differentiation in soil layer of p H,ammonium nitrogen,nitrate nitrogen,available phosphorus showed "N" type change trend;With the deepening of the soil layer,the stand age difference of soil C content,N content,moisture content,nitrate nitrogen,ammonium nitrogen,available phosphorus,aeration,N / P,C / P decreased,and the stand age difference of C / N is the opposite;the differentiation of soil layer and stand age of soil P are not significant.(5)The total soil nitrogen content of Larix principis-rupprechtii plantation showed an increasing trend and then a decreasing trend with the increase of stand age,and reached the maximum at 35 years,but the decomposition rate of organic N was lower and the soil available nitrogen is insufficient supplied.(6)The soil p H and bulk density of Larix principis-rupprechtii plantation became the main driving factors of soil C,N,P content and ecological stoichiometry.Among them,the soil p H in each layer was significantly positively correlated with soil C / N,and was significantly negatively correlated with soil C content.Except for 10-20 cm,the soil bulk density of other layers was significantly negatively correlated with soil N / P.(7)The nutrient requirements and nutrient utilization strategies of Larix principis-rupprechtii plantation vary significantly with the stage of growth and development.Young forests have high nitrogen requirements,and the available nitrogen in the soil is relatively inadequate.The way to adapt is to increase the rate of nutrient reabsorption.The demand for phosphorus in near-mature forests is high,and the total phosphorus and available phosphorus in the soil are relatively high.The way of absorbing nutrients from the soil can meet the growth needs.During the mature forest period,the soil total nitrogen and total phosphorus content were higher than those of the young forest,and the nutrient utilization strategy was consistent with that of the near mature forest.In order to maintain the sustainable development of Larix principis-rupprechtii plantation,different tending and management methods need to be adopted at different growth stages.Nitrogen fertilizer can be applied at the young stand age,phosphorus fertilizer should be added appropriately in middle-aged forests and near-maturity forests,and nitrogen and phosphorus fertilizers should be added properly at mature forests to improve soil fertility.