Leaf Traits Determine the Growth‐Survival Trade‐Off across Rain Forest Tree Species

Abstract

A dominant hypothesis explaining tree species coexistence in tropical forest is that trade-offs in characters allow species to adapt to different light environments, but tests for this hypothesis are scarce. This study is the first that uses a theoretical plant growth model to link leaf trade-offs to whole-plant performances and to differential performances across species in different light environments. Using data of 50 sympatric tree species from a Bolivian rain forest, we observed that specific leaf area and photosynthetic capacity codetermined interspecific height growth variation in a forest gap; that leaf survival rate determined the variation in plant survival rate under a closed canopy; that predicted height growth and plant survival rate matched field observations; and that fast-growing species had low survival rates for both field and predicted values. These results show how leaf trade-offs influence differential tree performance and tree species' coexistence in a heterogeneous light environment.Keywords: carbon, economy, growth-survival trade-off, leaf trade-off, rain forest trees, plant growth model.One way of understanding why plant species can coexist is by assuming that they partition resource gradients in space or time. Plant species from high-resource environments tend to have high resource acquisition rates, high resource turnover rates, and fast growth rates, whereas plant species from low-resource environments have lower acquisition and turnover rates and persist for a longer time. This general observation applies to a variety of plant communities, ranging from grasslands to forests. For example, grass species of eutrophic environments have higher nitrogen uptake and loss rates than grass species of oligotrophic environments (Berendse and Elberse 1989), and forest trees of high-light gaps have higher carbon uptake and loss rates than slow-growing trees that survive in the shade (Veneklaas and Poorter 1998;Walters and Reich 1999).From these observations it has been suggested that in productive environments, plants maximize their growth rates by continuously placing new roots or leaves in favorable patches. The high resource availability allows them to rapidly "pay back" the costs of producing leaves and roots. Conversely, in nonproductive environments, plants pay back the construction costs through slow turnover rates of roots and leaves and long residence times of key resources such as nitrogen and carbon in plant parts. Here, the slow turnover enhances the survival of a plant because otherwise, the species would run out of essential nutrient and carbon resources and die. Such a conservative resource-use strategy, however, comes at the expense of a reduced growth rate (Williams et al. 1989). These interactions between environmental productivity and turnover rates of plant components, carbon, and nutrients can thus explain the trade-off between growth and persistence across species (e

Growth and reproduction of vascular plants in polluted environments: a synthesis of existing knowledge

“…However, these early studies focussed mostly on visual symptoms and did not report quantitative data suitable for meta-analysis. The observed decrease in the proportion of studies conducted in these regions corresponds well to the decline in emissions following changes in industrial practices and the introduction of emission controls (Cape et al 2003;Stern 2006). The increase in the number of studies originating from Russia and the Ukraine in the 1990s was associated with the removal of governmental restrictions concerning publication of ''negative'' environmental information.…”

“…Although environmental pollution is an integral part of global change (Taylor et al 1994), a vast majority of the research addressing the biotic effects of global change overlooks this issue (but see, e.g., Settele et al 2005). The synthesis of existing knowledge on changes in plant growth and reproduction near industrial enterprises contributes to the integration of pollution ecology and global change research.…”

“…Although no data exists on the pollution effects on either aboveground or belowground biomass of mature trees, consistent decreases in leaf size, leaf number per shoot, and stem growth (both radial and vertical) suggest that woody plants do not compensate for pollution damage by changing resource allocation. However, overall growth reduction in woody plants may be seen not only as an indication of low vitality (Waring 1987) but also as an adaptive strategy increasing plant persistence (Sterck et al 2006). The second opinion is supported by observations demonstrating that some individuals of woody plants, in spite of reduced growth, survive in severely polluted industrial barrens for decades (Zverev et al 2008;Zverev 2009).…”

Changing gears during succession: shifting functional strategies in young tropical secondary forests

“…When and where resources are more available, species with trait values associated with resource acquisition are expected to perform better, while those with trait values associated with resource conservation exhibit better performance where resources are limiting (Rees et al 2001;Reich 2014). For example, Sterck et al (2006) found that high specific leaf area (SLA), photosynthesis rates, and leaf N content facilitated faster growth in forest gaps and that species with long-lived leaves and low SLA had higher survival rates under a closed canopy. However, not all functional traits or trait syndromes explain variation in ecological processes equally well (Lasky et al 2013Wright et al 2010).…”

“…Where species occur along this axis is strongly governed by the partitioning of resource gradients, principally light Sterck et al 2006Sterck et al , 2011Wright et al 2010), as well as soil nutrients (Russo et al 2008). Consequently, species-specific adaptations to Abstract Adaptations to resource availability strongly shape patterns of community composition along successional gradients in environmental conditions.…”