title: Tree Diversity Enhances Stand Carbon Storage but Not Leaf Area in a Subtropical Forest.
abstract: Research about biodiversity-productivity relationships has focused on herbaceous ecosystems, with results from tree field studies only recently beginning to emerge. Also, the latter are concentrated largely in the temperate zone. Tree species diversity generally is much higher in subtropical and tropical than in temperate or boreal forests, with reasons not fully understood. Niche overlap and thus complementarity in the use of resources that support productivity may be lower in forests than in herbaceous ecosystems, suggesting weaker productivity responses to diversity change in forests. We studied stand basal area, vertical structure, leaf area, and their relationship with tree species richness in a subtropical forest in south-east China. Permanent forest plots of 30 x 30 m were selected to span largely independent gradients in tree species richness and secondary successional age. Plots with higher tree species richness had a higher stand basal area. Also, stand basal area increases over a 4-year census interval were larger at high than at low diversity. These effects translated into increased carbon stocks in aboveground phytomass (estimated using allometric equations). A higher variability in tree height in more diverse plots suggested that these effects were facilitated by denser canopy packing due to architectural complementarity between species. In contrast, leaf area was not or even negatively affected by tree diversity, indicating a decoupling of carbon accumulation from leaf area. Alternatively, the same community leaf area might have assimilated more C per time interval in more than in less diverse plots because of differences in leaf turnover and productivity or because of differences in the display of leaves in vertical and horizontal space. Overall, our study suggests that in species-rich forests niche-based processes support a positive diversity-productivity relationship and that this translates into increased carbon storage in long-lived woody structures. Given the high growth rates of these forests during secondary succession, our results further indicate that a forest management promoting tree diversity after disturbance may accelerate CO2 sequestration from the atmosphere and thus be relevant in a climate-change context.
authors.affiliation: Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland.
authors.forename: Nadia
authors.initials: N
authors.lastname: Castro-Izaguirre
authors.affiliation: Department of Ecology, College of Urban and Environmental Sciences, and Key Laboratory for Earth Surface Processes of Ministry of Education, Peking University, Beijing, China.
authors.forename: Xiulian
authors.initials: X
authors.lastname: Chi
authors.affiliation: Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland.
authors.forename: Martin
authors.initials: M
authors.lastname: Baruffol
authors.affiliation: Department of Ecology, College of Urban and Environmental Sciences, and Key Laboratory for Earth Surface Processes of Ministry of Education, Peking University, Beijing, China.
authors.forename: Zhiyao
authors.initials: Z
authors.lastname: Tang
authors.affiliation: Institute of Botany, Chinese Academy of Sciences, Beijing, China.
authors.forename: Keping
authors.initials: K
authors.lastname: Ma
authors.affiliation: Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Schmid
authors.affiliation: Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland.
authors.forename: Pascal A
authors.identifier: http://orcid.org/0000-0002-2360-1357
authors.initials: PA
authors.lastname: Niklaus
mesh_terms: D044822:Biodiversity; D018533:Biomass; D002244:Carbon / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism*; D057965:Carbon Sequestration; D002681:China; D057231:Climate Change; D065928:Forests; D018515:Plant Leaves / Q000033:anatomy & histology / Q000502:physiology*; D014197:Trees / Q000033:anatomy & histology / Q000502:physiology*; D014329:Tropical Climate
chemical_list: D002245:Carbon Dioxide; D002244:Carbon