N concentration of old leaves and twigs is more sensitive to stand density than that of young ones in Chinese fir plantations： a case study in subtropical China  

作　　者：Yuebao Di Xiaoli Fu Huimin Wang Wenhua Li Silong Wang 

机构地区：[1]Qianyanzhou Ecological Research Station, Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, People's Republic of China [2]College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100190, People's Republic of China [3]Jiangxi Key Laboratory of Ecosystem Processes and Information, Ji'an 343725, People's Republic of China [4]Huitong Experimental Station of Forest Ecology, Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Sbenyang 110016, People' s Republic of China

出　　处：《Journal of Forestry Research》2018年第1期163-169,共7页林业研究（英文版）

基　　金：supported by the NSFC Projects of International Cooperation and Exchanges(31210103920);the National Key Research and Development Program(2016YFD0600202);the Gan-Po Distinguished Researcher Program;the Project of Jiangxi Provincial Department of Science and Technology(20144BBB70005)

摘　　要：Young leaves are conventionally used in the analysis to study the nutrient status of evergreen plants and their responses to environmental changes, but the role of old leaves remains poorly understood. We selected two stand types in 31-year-old Chinese fir（Cunninghamia lanceolata） plantations with similar soil conditions but different stand densities, to test the hypothesis that nitrogen（N） concentration of old leaves and twigs is more sensitive to stand density than that of young ones. Leaves and twigs were sampled and sorted into young（one-year-old） and old（two-and three-year-old） groups. Significant differences in N concentration and carbon： nitrogen ratio between the low-density stand and high-density stand were only found in the old leaves and twigs but not in the young ones.Although the N resorption efficiency did not vary significantly with stand density, the annual N resorption rates were increased in old leaves and relatively young twigs at high stand density. These results show the potential use of old tissues in the nutrient analysis in Chinese fir plantations. Testing the generality of these results could improve the use of foliar analysis as an indicator of nutrient status and environmental changes in evergreen tree species.Young leaves are conventionally used in the analysis to study the nutrient status of evergreen plants and their responses to environmental changes, but the role of old leaves remains poorly understood. We selected two stand types in 31-year-old Chinese fir（Cunninghamia lanceolata） plantations with similar soil conditions but different stand densities, to test the hypothesis that nitrogen（N） concentration of old leaves and twigs is more sensitive to stand density than that of young ones. Leaves and twigs were sampled and sorted into young（one-year-old） and old（two-and three-year-old） groups. Significant differences in N concentration and carbon： nitrogen ratio between the low-density stand and high-density stand were only found in the old leaves and twigs but not in the young ones.Although the N resorption efficiency did not vary significantly with stand density, the annual N resorption rates were increased in old leaves and relatively young twigs at high stand density. These results show the potential use of old tissues in the nutrient analysis in Chinese fir plantations. Testing the generality of these results could improve the use of foliar analysis as an indicator of nutrient status and environmental changes in evergreen tree species.

关 键 词：Foliar analysis TWIG Nitrogen Nutrient resorption Stand density 

分 类 号：S718.5[农业科学—林学]