The response of tree growth to nitrogen and phosphorus additions in a tropical montane rainforest

Lai Jiang; Di Tian; Suhui Ma; Xuli Zhou; Longchao Xu; Jianxiao Zhu; Xin Jing; Chengyang Zheng; Haihua Shen; Zhang Zhou; Yide Li; Biao Zhu; Jingyun Fang

doi:10.1016/j.scitotenv.2017.09.099

The response of tree growth to nitrogen and phosphorus additions in a tropical montane rainforest

Sci Total Environ. 2018 Mar 15:618:1064-1070. doi: 10.1016/j.scitotenv.2017.09.099. Epub 2017 Nov 7.

Authors

Lai Jiang¹, Di Tian², Suhui Ma², Xuli Zhou², Longchao Xu³, Jianxiao Zhu², Xin Jing², Chengyang Zheng², Haihua Shen³, Zhang Zhou⁴, Yide Li⁴, Biao Zhu², Jingyun Fang²

Affiliations

¹ Department of Ecology, College of Urban and Environmental Sciences, Key Laboratory for Earth Surface Processes of the Ministry of Education, Peking University, Beijing 100871, China. Electronic address: jiangl@pku.edu.cn.
² Department of Ecology, College of Urban and Environmental Sciences, Key Laboratory for Earth Surface Processes of the Ministry of Education, Peking University, Beijing 100871, China.
³ State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
⁴ Research Institute of Tropical Forestry, Chinese Academy of Forestry, Guangzhou 520510, China.

PMID: 29126640
DOI: 10.1016/j.scitotenv.2017.09.099

Abstract

Rapid increase of global nitrogen (N) deposition has greatly altered carbon cycles and functioning of forest ecosystems. Previous studies have focused on changes in carbon dynamics of temperate and subtropical forests through N enrichment experiments; however, the effects of N deposition on tree growth remain inconsistent, especially in tropical forests. Here, we conducted a five-year N addition experiment (0 and 50kgNha^-1yr^-1) in a tropical montane rain forest in Hainan Island, China, to explore the effects of enhanced N deposition on growth of trees. We also set phosphorus (P) treatment (50kgPha^-1yr^-1) and N+P treatment (50kgNha^-1yr^-1+50kgPha^-1yr^-1) to examine potential P limitation driven by N deposition. Our results showed that N addition has not significantly influenced tree growth, while P addition significantly increased the relative growth rate of small (diameter at breast height, DBH≤10cm) and medium (10<DBH≤20cm) trees. The combined N and P addition accelerated the growth of small trees, but did not affect the growth of medium and large (20cm<DBH) trees. These contrasting effects of N and P addition on tree growth indicate that the tropical montane forest is mainly limited by P, which suggests the importance of P in regulating growth of trees in tropical forests.

Keywords: Limitation; Nitrogen deposition; Phosphorus; Tree growth; Tropical forest.