Evolutionary Position and Leaf Toughness Control Chemical Transformation of Litter, and Drought Reinforces This Control: Evidence from a Common Garden Experiment across 48 Species

RESEARCH ARTICLE Evolutionary Position and Leaf Toughness Control Chemical Transformation of Litter, and Drought Reinforces This Control: Evidence from a Common Garden Experiment across 48 Species a11111 OPEN ACCESS Citation: Pan X, Song Y-B, Jiang C, Liu G-F, Ye X-H, Xie X-F, et al. (2015) Evolutionary Position and Leaf Toughness Control Chemical Transformation of Litter, and Drought Reinforces This Control: Evidence from a Common Garden Experiment across 48 Species. PLoS ONE 10(11): e0143140. doi:10.1371/journal. pone.0143140 Editor: Martin Schädler, Helmholtz Centre for Environmental Research (UFZ), GERMANY Received: July 17, 2015 Accepted: October 30, 2015 Published: November 17, 2015 Copyright: © 2015 Pan et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: All relevant data are within the paper and its Supporting Information files. Funding: This work was supported by the NSFC (Grant 31261120580, 31400346) and the Innovative R & D grant (201203) from Hangzhou Normal University. This work was also funded by China Postdoctoral Science Foundation funded project. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Xu Pan1,2,3, Yao-Bin Song1, Can Jiang1, Guo-Fang Liu3, Xue-Hua Ye3, Xiu-Fang Xie1,3, YuKun Hu1,3, Wei-Wei Zhao3,4, Lijuan Cui2, Johannes H. C. Cornelissen4, Ming Dong1,3*, Andreas Prinzing5 1 Key Laboratory of Hangzhou City for Ecosystem Protection and Restoration, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China, 2 Institute of Wetland Research, Chinese Academy of Forestry, Beijing, China, 3 State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China, 4 Systems Ecology, Department of Ecological Science, Faculty of Earth and Life Sciences, VU University Amsterdam, 1081 HV Amsterdam, The Netherlands, 5 Université de Rennes 1, Centre National de la Recherche Scientifique Campus de Beaulieu, Research Unit Ecobio, Bâtiment 14 A, 35042 Rennes, France * Abstract Plant leaf litter is an important source of soil chemicals that are essential for the ecosystem and changes in leaf litter chemical traits during decomposition will determine the availability of multiple chemical elements recycling in the ecosystem. However, it is unclear whether the changes in litter chemical traits during decomposition and their similarities across species can be predicted, respectively, using other leaf traits or using the phylogenetic relatedness of the litter species. Here we examined the fragmentation levels, mass losses, and the changes of 10 litter chemical traits during 1-yr decomposition under different environmental conditions (within/above surrounding litter layer) for 48 temperate tree species and related them to an important leaf functional trait, i.e. leaf toughness. Leaf toughness could predict the changes well in terms of amounts, but poorly in terms of concentrations. Changes of 7 out of 10 litter chemical traits during decomposition showed a significant phylogenetic signal notably when litter was exposed above surrounding litter. These phylogenetic signals in element dynamics were stronger than those of initial elementary composition. Overall, relatively hard-to-measure ecosystem processes like element dynamics during decomposition could be partly predicted simply from phylogenies and leaf toughness measures. We suggest that the strong phylogenetic signals in chemical ecosystem functioning of species may reflect the concerted control by multiple moderately conserved traits, notably if interacting biota suffer microclimatic stress and spatial isolation from ambient litter. PLOS ONE | DOI:10.1371/journal.pone.0143140 November 17, 2015 1 / 15 Chemical Traits Change during Decomposition Competing Interests: The authors have declared that no competing interests exist. Introduction Leaf litter decomposition is an important ecosystem process [1–3]. Many studies focus on overall mass loss of leaf litter, but during the decomposition processes also chemical traits might change significantly due to the release of various chemical elements from or their immobilization in litter [2–5]. For instance, amounts of phosphorus (P), and sometimes sulphur (S) may increase during the initial stages of decomposition (possibly owing to import by microbes), followed by a decrease [6,7], while Ca, K, Mg and Mn amounts usually continuously decrease [1]. Concentration of N, P and Ca increase in most litter, while Mg and S remain constant and K sometimes decreases [1,6–9], see also [4,10,11]. Previous studies mainly focused on litter chemical transformation of single species [11–16] or of litter mixtures [12,17]. Many of these studies found differences among elements or ecosystems concerned [4,10,12,17], but see [1,8,12,18,19,20]. However, studies across many species comparing species traits to chemical litter transformation are still missing. Ecosystem processes may be driven by plant traits [21]. Mass loss during decomposition, for instance, can often be represented by easy-to-assess ‘soft’ leaf trait values [22]. However, few studies have tried to examine whether and how the patterns of change of litter chemical traits during decomposition across species can be predicted from species traits. Changes of litter chemical traits during decomposition are considered to be determined by the initial litter traits and the nutrient availability to decomposers [3,6,23,24]. Moreover, litter chemical changes might also link to initial litter physical traits, such as litter toughness (usually termed as leaf tensile strength). This physical soft trait was proven to have strong negative effects on the decomposition rates across multiple species [25,26]. In fact, given that leaf and litter toughness are strongly correlated, leaf toughness was usually chosen as an indicator of physical afterlife litter quality and related to litter decomposition rate [10,25,26]. However, no study has systematically tested whether litter or leave toughness is a good predictor for the changes of multiple litter chemical traits during decomposition. Here, we hypothesized that leaf toughness might be a good driver for the changes of litter chemical traits during decomposition. Functional traits may be more similar among close than among distantly related species (phylogenetic signal, e.g. [27]) and it has been suggested that phylogenetic structure of communities may influence their ecosystem functioning (e.g. [28]). The phylogenetic signal in species functional traits may hence translate into a phylogenetic signal in the ecosystem functioning of species, including in the chemical transformation of plant litter. Phylogenetic signal (...truncated)