关 键 字(英文)：Nitrogen addition Tree growth Dinghushan Biosphere Reserve Guangdong
摘 要(英文)：The responses of diameter at breast height (DBH) in tree layer to nitrogen (N) additions were studied in three representative forest types in Dinghushan Biosphere Reserve: a pine (Pinus massoniana) forest, a pine- broadleaved mixed forest, and a broadleaved forest. Dissolved NH4NO3 was sprayed monthly with equal appli- cations dose onto the forest floor of 10 m×20 m plots within a year to simulated elevated N deposition. Four treat- ments were established in the broadleaved forest: control, low N (50 kg N hm-2a-1), moderate N (100 kg N hm-2a-1) and high N (150 kg N hm-2a-1), and three treatments (control, low N and moderate N), in mixed and pine forests. All the treatments were in three replicates. Annual increment rates of DBH in control plots were estimated to be 4.84%, 4.09% and 2.99% for the pine, mixed and broadleaved forests, respectively. After treatment with N additions for one year, in the pine and mixed forest, the DBH increment rate in low N plots was similar to that in the control, while in moderate N plots the increment rates in pine forest and mixd forest were by 77.8% and 105.6%, respectively, higher than those of the control. In contrast, in the broadleaved forest, all N addition treatments decreased the tree growth, though the treatment effect was not significant, and increment rates in the low, moderate and high N plots were by 36.8%,28.5% and 41.0%, respectively, lower as compared to the control. The effects of N addition on tree growth different in species. N additions stimulated the growth of Pinus massoniana both in pine forest and mixed forest, but decreased that of most broadleaved species in all the three forests.
鼎湖山主要森林类型植物胸径生长对氮沉降增加的初期响应 