The role of climate and plant functional trade-offs in shaping global biome and biodiversity patterns

Abstract

Aim Two of the oldest observations in plant geography are the increase in plant diversity from the poles towards the tropics and the global geographic distribution of vegetation physiognomy (biomes). The objective of this paper is to use a processbased vegetation model to evaluate the relationship between modelled and observed global patterns of plant diversity and the geographic distribution of biomes. LocationThe global terrestrial biosphere. MethodsWe implemented and tested a novel vegetation model aimed at identifying strategies that enable plants to grow and reproduce within particular climatic conditions across the globe. Our model simulates plant survival according to the fundamental ecophysiological processes of water uptake, photosynthesis, reproduction and phenology. We evaluated the survival of an ensemble of 10,000 plant growth strategies across the range of global climatic conditions. For the simulated regional plant assemblages we quantified functional richness, functional diversity and functional identity.Results A strong relationship was found (correlation coefficient of 0.75) between the modelled and the observed plant diversity. Our approach demonstrates that plant functional dissimilarity increases and then saturates with increasing plant diversity. Six of the major Earth biomes were reproduced by clustering grid cells according to their functional identity (mean functional traits of a regional plant assemblage). These biome clusters were in fair agreement with two other global vegetation schemes: a satellite image classification and a biogeography model (kappa statistics around 0.4). Main conclusionsOur model reproduces the observed global patterns of plant diversity and vegetation physiognomy from the number and identity of simulated plant growth strategies. These plant growth strategies emerge from the first principles of climatic constraints and plant functional trade-offs. Our study makes important contributions to furthering the understanding of how climate affects patterns of plant diversity and vegetation physiognomy from a process-based rather than a phenomenological perspective.

Plant communities as drivers of soil respiration: pathways, mechanisms, and significance for global change

“…Clark et al (2007) argue that within species variation in plant properties can explain and alleviate this problem, and that the standard approach of using mean species properties to drive CCM's is flawed, because coexistence is greatly facilitated by within species (or plant type) genetic and environmentally modulated heterogeneity. One promising framework is provided by the JeDi model (Reu et al, 2010) that generates a theoretical plant community whose traits vary along twelve functional trade-off gradients. A coupled plant physiology model selects a subset of plant physiological strategies that survive under a given set of climate conditions.…”

“…Finally, given the likelihood of future large scale shifts in the distribution, composition and diversity of plant communities driven by climate change (Neilson et al, 2005), we discuss the contrasting approaches taken by major models to simulate species effects on ecosystem C cycling Friedlingstein et al, 2006;Ostle et al, 2009;Reu et al, 2010). In doing so, we highlight potentially important ecological processes currently missing from the model frameworks, evaluate approaches to integrating field data into effective model representations of the processes in question, and suggest priorities for future research.…”

The relative importance of seed competition, resource competition and perturbations on community structure

“…DIVE calculates population dynamics as the consequence of different characteristics of PPSs in terms of their biomass, seed flux, growth and mortality rate. These characteristics are derived from the output of the Jena Diversity (JeDi) model (Kleidon and Mooney, 2000;Reu et al, 2011). This model filters many random plant strategies that grow independently from each other to yield those, that can cope with the climate from the fundamental assumption of unavoidable ecophysiological trade-offs.…”

“…We used the JeDi model (Kleidon and Mooney, 2000;Reu et al, 2011) to generate the performances of a whole range of PPSs. JeDi models diverse vegetation from ecophysiological assumptions based on trade-offs.…”

“…DIVE calculates population dynamics based on establishment, mortality, invasion and exclusion as distinct processes that are shaped by competition between seeds for available space, competition for resources and perturbations. The rates of establishment, mortality, invasion and exclusion are linked to the modelled emergent performances of different plant strategies derived from an individual-based plant model (Kleidon and Mooney, 2000;Reu et al, 2011), that covers how individual plant strategies cope with their environment without considering interspecies competition. By doing so, we do not need to predefine the dominance or the colonization rates of the PFTs.…”