Management Effects Of Different Thinning Strength On Aerial Seeding Pinus Tabuliformis Stands

Pinus tabuliformis is the main aerial seeding tree species in Shaanxi Province,and the Aerial forest of P.tabuliformis is an important part of the plantation forest in the upper reaches of the Danjiang River.Tending thinning is one of the main managements means to cultivate aerial seeding forest.The long-term effects of thinning on the growth and development of artificial forest can provide decision-making basis to achieving different management objectives of aerial seeding forest of P.tabuliformis.In this study,the aerial forest of P.tabuliformis in Danfeng County,Shangluo City was taken as the research object.Studying of community characteristics,carbon storage,and soil physical and chemical properties after 23 years of different thinning intensity management(Heavy(69.8%:retention density 1200 plants/hm~2),Medium(53.4%:1800 plants/hm~2),Light(22.7%:3000 plants/hm~2),4000 plants/hm~2(control))were studied,the aim to explore the suitable management density of aerial forest of P.tabuliformis in Danfeng County,and provide a basis for the healthy management and sustainable development of aerial forest of P.tabuliformis in Shaanxi.Our main results as follows:(1)Tending and thinning significantly changed the community characteristics of aerial forest of P.tabuliformis,promoting the DBH,tree height and crown width growth,and optimizing the diameter-step structure of the stand.The DBH,tree height,crown width and diameter structure of the intensity thinning stand were the best,followed by the moderate thinning stand.With the increase of thinning intensity,the individual stand volume increased,and the stand volume under light and moderate thinning was higher than that under control,the stand volume under intensity thinning was the least.Intensity thinning and moderate thinning significantly increased the species of understory,and the plant diversity of intensity thinning was the highest than other thinning methods.(2)Tending thinning changed the natural regeneration pattern,optimized the height structure and promoted seedling growth under the Aaerial forest of P.tabuliformis.In addition,moderate and intense thinning increased the diversity of seedling saplings and emerged the P.tabuliformis seedlings regeneration,firstly.Intense.Under intensity thinning,the diversity index and number of saplings were the largest,and the height structure distribution was reasonable,and the proportion of broad-leaved trees such as Quercus was high,which was conducive to the development of the stand to the mixed broadleaf-conifer forest.(3)The order of the carbon storage of the Aaerial forest of P.tabuliformis was tree,soil layer,litter,shrub-grass.Soil carbon storage of thinning was lower than that of control,which indicated that thinning was not good to soil carbon sequestration.The carbon storage of P.tabuliformis forest of Pinus tabuliformis ecosystem with light thinning is the highest,which is the most suitable thinning intensity to increase the carbon sink of ecosystem and cultivate the wood,and intensive thinning significantly reduced the system of Aaerial forest of P.tabuliformis carbon storage.(4)The soil of aerial forest of Pinus tabuliformis was poor,and its total soil nutrients(phosphorus and nitrogen)and available nutrients(ammonium nitrogen)content were low.Tending felling significantly improved the soil quality properties,and increased soil moisture,total nitrogen and phosphorus.