Response of tree growth to nitrogen addition in a Larix gmelinii primitive forest |
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Authors: | LIU Xiu-Yuan DU En-Zai XU Long-Chao SHEN Hai-Hua FANG Jing-Yun HU Hui-Feng |
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Affiliation: | State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China University of Chinese Academy of Sciences, Beijing 100049, China and College of Urban and Environmental Sciences, and Key Laboratory for Earth Surface Processes of the Ministry of Education, Peking University, Beijing 100871, China |
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Abstract: | Aims Global nitrogen (N) deposition has been consistently enhanced and significantly influenced the carbon (C) cycle of forest ecosystem. However, studies on the quantitive response of C sequestration to N deposition in China’s boreal forest ecosystem still remains insufficient. Tree growth is one of important components of C sequestration in forest ecosystem. In order to accurately evaluate the influence of N deposition on C sequestration in China’s boreal forest ecosystem, This study was designed to investigate how N deposition influenced the tree diameter at breast height (DBH) growth of a Larix gmelinii primitive forest. Methods We carried out a N enrichment experiment in an L. gmelinii primitive forest in Greater Khingan Mountains with four N addition levels (control (0), low N (20 kg N·hm-2·a-1), medium N (50 kg N·hm-2·a-1) and high N (100 kg N·hm-2·a-1)). DBH was measured from 2012-2014 within all treatments. Important findings Medium N and high N additions significantly influenced the relative DBH growth of L. gmelinii, and the influence became more pronounced through time. N deposition significantly affected the DBH growth among different tree height classes: low height class (tree height <16.5 m) did not show significant response to N deposition, while high height class (tree height >16.5 m) showed significantly accelerated growth under medium and high N additions (the relevant DBH growth rate >79.5%), and this acceleration effect decreased as the tree height increased. This study indicated that N addition did enhance the DBH growth of L. gmelinii, but this enhancement mainly affected taller L. gmelinii trees. |
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Keywords: | boreal forest diameter at breast height Larix gmelinii nitrogen deposition tree growth |
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