title: Determinants of the N content of Quercus wutaishanica leaves in the Loess Plateau: a structural equation modeling approach.
abstract: Most terrestrial ecosystems are nitrogen (N)-limited. The elucidation of the multivariate relationships among environmental drivers, leaf morphological traits, and foliar N of dominant species which are critical to the functioning of forests remains a critical challenge for ecologists. We sampled leaves of Quercus wutaishanica across a broad natural gradient in the Loess Plateau, China, and employed structural equation modelling to evaluate the causal pathways and the relative importance of drivers of the foliar N per unit area (Narea) and per unit mass (Nmass). We found that (1) Nmass and Narea were primarily affected by leaf morphological traits instead of environmental variables and that leaf morphological traits accounted for most of their variations; (2) the total soil potassium and phosphorus and mean annual precipitation had different effects on Nmass and Narea via different pathways and path coefficients, whereas the mean annual temperature and total soil N had non-significant effects on Nmass and Narea. Our results demonstrated that variations in Nmass and Narea within Quercus wutaishanica were strongly linked to their leaf morphological traits and that the leaf N was also influenced by mean annual precipitation and soil phosphorus and potassium instead of soil N in the Loess Plateau, China.
authors.affiliation: State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875, China.|College of Resources Science &Technology, Beijing Normal University, Beijing 100875, China.
authors.forename: Kaixiong
authors.initials: K
authors.lastname: Xing
authors.affiliation: State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875, China.|College of Resources Science &Technology, Beijing Normal University, Beijing 100875, China.
authors.forename: Muyi
authors.initials: M
authors.lastname: Kang
authors.affiliation: Faculty of Natural Resources Management, Lakehead University, 955 Oliver Road, Thunder Bay, ON P7B 5E1, Canada.
authors.forename: Han Y H
authors.initials: HYH
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875, China.|College of Resources Science &Technology, Beijing Normal University, Beijing 100875, China.
authors.forename: Mingfei
authors.initials: M
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875, China.|College of Resources Science &Technology, Beijing Normal University, Beijing 100875, China.
authors.forename: Yuhang
authors.initials: Y
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875, China.|College of Resources Science &Technology, Beijing Normal University, Beijing 100875, China.
authors.forename: Guoyi
authors.initials: G
authors.lastname: Wang
authors.affiliation: College of Life Sciences, Beijing Normal University, Beijing 100875, China.
authors.forename: Chen
authors.initials: C
authors.lastname: Chen
authors.affiliation: Human Resource Development Center, Ministry of Land and Resources, Beijing 100812, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875, China.|College of Resources Science &Technology, Beijing Normal University, Beijing 100875, China.
authors.forename: Xiaobin
authors.initials: X
authors.lastname: Dong