PhD candidate HUANG Liujing and her supervisor Dr. REN Hai at South China Botanical Garden, CAS, the pattern of atmospheric N deposition along an urban–rural gradient in metropolitan Guangzhou, southern China, and assessed the potential influence of N deposition on soil properties and understory plant diversity in remnant forests. They found that a steep urban-to-rural N deposition gradient exists in the metropolitan region of Guangzhou in southern China. They suggested that rapid urbanization and the associated high atmospheric N pollution may lead to the reduced herb-layer diversity; (2) the decline in herb-layer diversity appeared to result from N-related changes in soil properties (i.e., decreases in pH and loss of extractable Ca and K) rather than from the competition-based mechanisms typical of forests with more N-efficient dominant species. Increased N deposition results in soil acidification and nutrients leaching that reduce the growth and survival of N-sensitive plants;(3) plant diversity responses to N deposition reflected changes in herb-layer species with particular functional traits, i.e., forbs and ferns are more N-sensitive than tree seedlings and grasses to elevated N deposition. These findings have important implications for the management of remnant forests. A regional policy linking atmospheric pollution and land protection is needed to protect the most N-sensitive herb species (e.g., forbs and ferns) in these remnant forests.

This work has been published in Plant Ecology (Liujing Huang, Weixing Zhu, Hai Ren*, Hongfeng Chen, Jun Wang. Impact of atmospheric nitrogen deposition on soil properties and herb-layer diversity in remnant forests along an urban-rural gradient in Guangzhou, southern China. Plant Ecology. DOI 10.1007s11258-012-0080-y). This study was funded by the ‘Eleventh Five-Year’ National Key Technology Program (2008 BAJ10B03-5) and the Kadoorie Farm and Botanic Garden Corporation, and National Natural Science Foundation of China (40871249, 31100469).