The Effect Of Thinning Intensity On Carbon Distribution Pattern Of Typical Forest Stands In Nanjing Lishui Forestry Farm

In order to explore the effects of thinning on carbon distribution pattern, we studied three typical forest stands in Nanjing suburban, including Cunninghamia lanceolata(Lamb.)Hook pure forest, Quercus acutissima Carruth.+Quercus chenii Nakai. mixed forest and Cunninghamia lanceolata(Lamb.)Hook.+Quercus chenii Nakai. mixed forest. Aiming at finding out the most appropriate intensity of thinning to manage urban forest and providing a theoretical basis for the sustainable management for urban forest, we set up four thinning intensity for each forest stand, light thinning(20%~30%), the number of trees intensity, the same below), medium thinning(40%~50%), heavy thinning(60%~70%) and un-thinning(CK). The results show as below:1. Compared with the control check, the growth of individual(diameter at breast height(DBH), crown diameter and volume) increased significantly with thinning intensity. But thinning had no consistency effects on tree height. The volume of stand was decreased, while the species and diversity of under-story increased. Thinning increased understory tree species of all forest stands, but the regeneration of understory varied with thinning intensity and forest stands.2. With increasing thinning intensity, the content of clay and the annual average temperature was increased but the bulk weight and humidity of soil layer decreased significantly besides Cunninghamia lanceolata(Lamb.)Hook. After thinning, the content of TC, TN and TP increased, but it had no significant effects on pH. The soil microbial biomass carbon(MBC) and soil microbial biomass nitrogen(MBN) increased significantly, but MB(C/N) did not change obviously.3. Thinning changed the carbon storage. In the Cunninghamia lanceolata(Lamb.) pure stand, it has increased by 2.86 t·hm-2 and 7.83 t·hm-2 in LIT and MIT respectively, but decreased by 2.85 t·hm-2 in HIT. The carbon storage decreased in Quercus acutissima Carruth.+Quercus chenii Nakai.mixed forest. In the Cunninghamia lanceolata(Lamb.)Hook.+Quercus chenii Nakai.mixed forest, the carbon storage was increased by 2.91 t·hm-2 in LIT, but decreased by 1.19 t·hm-2 26.43 t·hm-2 respectively in MIT and HIT4. Thinning changed the distribution pattern of carbon storage. Compared with the control check, the carbon storage of tree layer had decreased by 2.70%~14.72% with increasing thinning intensity despite of Cunninghamia lanceolata(Lamb.) pure stand. The carbon storage of bush layer had increased by 0.04%~0.45% with intensity. The carbon storage of soil layer had increased by 3.05%~14.53% with intensity despite of Cunninghamia lanceolata(Lamb.).