title: Net Assimilation Rate Determines the Growth Rates of 14 Species of Subtropical Forest Trees.
abstract: Growth rates are of fundamental importance for plants, as individual size affects myriad ecological processes. We determined the factors that generate variation in RGR among 14 species of trees and shrubs that are abundant in subtropical Chinese forests. We grew seedlings for two years at four light levels in a shade-house experiment. We monitored the growth of every juvenile plant every two weeks. After one and two years, we destructively harvested individuals and measured their functional traits and gas-exchange rates. After calculating individual biomass trajectories, we estimated relative growth rates using nonlinear growth functions. We decomposed the variance in log(RGR) to evaluate the relationships of RGR with its components: specific leaf area (SLA), net assimilation rate (NAR) and leaf mass ratio (LMR). We found that variation in NAR was the primary determinant of variation in RGR at all light levels, whereas SLA and LMR made smaller contributions. Furthermore, NAR was strongly and positively associated with area-based photosynthetic rate and leaf nitrogen content. Photosynthetic rate and leaf nitrogen concentration can, therefore, be good predictors of growth in woody species.
authors.affiliation: Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland.|Department of Physics, Helsinki University, Helsinki, Finland.
authors.forename: Xuefei
authors.initials: X
authors.lastname: Li
authors.affiliation: Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Schmid
authors.affiliation: West China Subalpine Botanical Garden, Institute of Botany, Chinese Academy of Sciences, Dujiangyan, China.
authors.forename: Fei
authors.initials: F
authors.lastname: Wang
authors.affiliation: Biological and Environmental Sciences, University of Stirling, Stirling, United Kingdom.
authors.forename: C E Timothy
authors.initials: CE
authors.lastname: Paine
mesh_terms: D018533:Biomass; D065928:Forests; D008027:Light; D019655:Quantitative Trait, Heritable; D014197:Trees / Q000254:growth & development*; D014329:Tropical Climate