Contrasting effects of productivity and disturbance on plant functional diversity at local and metacommunity scales

Abstract

Questions Is trait convergence more intense when soil resource availability and disturbance constrain productivity and limit above‐ground competition? Do the effects of productivity and disturbance on functional diversity differ between the local and metacommunity scales? Location Semi‐arid grasslands in New Zealand (43°59′ S, 170°27′ E). Methods We measured trait convergence and divergence in grasslands along gradients of primary productivity and disturbance at local (i.e. 1 m × 1 m) and metacommunity (8 m × 50 m) scales, using long‐term (27‐yr) manipulations of soil resource availability and grazing intensity. We compared trait dispersion metrics to those expected under different null models. Results At the metacommunity scale, we found stronger trait convergence with increasing productivity and grazing intensity, where all short, slow‐growing species were excluded from the potential species pool. However, once this broad‐scale filter on species pool was taken into account, we found that at the local scale, abundance‐weighted functional dispersion of co‐occurring species was stronger than expected under our null model, thereby suggesting limiting similarity. Moreover, trait divergence became stronger at higher productivity and lower grazing intensity, where size‐asymmetric competition for light is likely to have been more intense. Conclusions At the metacommunity scale, environmental filtering led to species with particular traits being excluded from the species pool. In contrast, at the local community scale where individuals interact, there was evidence of limiting similarity. Our results suggest that environmental filtering and limiting similarity are not mutually exclusive and jointly determine community structure, but can operate at different spatial scales.

Disturbance by an endemic rodent in an arid shrubland is a habitat filter: effects on plant invasion and taxonomical, functional and phylogenetic community structure

“…For instance, it has been shown that facilitation may promote functional divergence in the resource-poor alpine tundra (Spasojevic and Suding, 2012). However, this pattern is opposite to what we expected to find assuming a habitatfiltering process: disturbance promoting functional convergence (Mouillot et al, 2013;Laliberté et al, 2013).…”

“…We cannot rule out, however, that other unmeasured traits might be involved in the response to increased disturbance (e.g. plant height or foliar nitrogen content; Laliberté et al, 2013), and consequently might change phylogenetic community structure. Earlier studies in arid and semi-arid environments have reported that natural disturbance by S. cyanus favours the dominance of annual plants (Contreras et al, 1993) and can promote invasion by exotic species despite the relatively stressful conditions (Contreras and Gutierrez, 1991;Torres-D ıaz et al, 2012).…”

“…Generally, increased disturbance reduces fitness of resident plant species, and by reducing the number of dominant species and releasing space and resources it may lessen the importance of interspecific competition in the community (Huston, 1979;Dinnage, 2009). Thus, disturbance is likely to tip the balance in favour of habitat filtering and against limiting similarity as the main process driving community structure (Mouillot et al, 2013;Laliberté et al, 2013). In unproductive environments where only plants with particular traits or strategies can establish and persist, we expect habitat filtering to become the dominant assembly process under the influence of disturbance (Kraft et al, 2015).…”

Grass strategies and grassland community responses to environmental drivers: a review

“…The selection and complementarity effects distinguish the effects of very productive and dominant species to the complementarity in resource utilization by different species. Three grassland communities of six grass species across four management treatments (two cut frequencies and two levels of nitrogen fertilization) and throughout 2 years were explored in this study (n=24 for species assembling (Mason et al 2011;Spasojevic and Suding 2012;Gerhold et al 2013;Laliberté et al 2013;Price et al 2014;Carboni et al 2014). For instance, along an environmental severity gradient in productive grassland communities, Maire et al (2012a, see also Bernard-Verdier et al 2012 as another example along a natural soil fertility gradient in Mediterranean rangelands) found that convergence pattern towards high plant stature traits was the predominant force to explain species abundance in fertile and less disturbed habitat.…”

Fuzzy Index and Self-Organizing Feature Map Index for Measuring Functional Diversity Applied to Acanthopanax Senticosus Communities

“…Functional diversity in communities is a key driver of ecosystem processes, ecosystem resilience to environmental change, and ecosystem services [2,3]. Functional diversity refers to the change of species functions in communities, and species functions are reflected by functional traits, i.e.…”