Plant–soil feedbacks and the coexistence of competing plants

Abstract

Plant-soil feedbacks can have important implications for the interactions among plants. Understanding these effects is a major challenge since it is inherently difficult to measure and manipulate highly diverse soil communities. Mathematical models may advance this understanding by making the interplay of the various processes affecting plant-soil interaction explicit and by quantifying the relative importance of the factors involved. The aim of this paper is to provide a complete analysis of a pioneering plant-soil feedback model developed by Bever and colleagues (J Ecol 85: 561-573, 1997; Ecol Lett 2: 52-62, 1999; New Phytol 157: 465-473, 2003) to fully understand the range of possible impacts of plant-soil feedbacks on plant communities within this framework. We analyze this model by means of a new graphical method that provides a complete classification of the potential effects of soil communities on plant competition. Due to the graphical character of the method, the results are relatively easy to obtain and understand. We show that plant diversity depends crucially on two key parameters that may be viewed as measures of the intensity of plant competition and the direction and strength of plantsoil feedback, respectively. Our analysis provides a formal underpinning of earlier claims that plant-soil feedbacks, especially when they are negative, may enhance the diversity of plant communities. In particular, negative plant-soil feedbacks can enhance the range of plant coexistence by inducing competitive oscillations. However, these oscillations can also destabilize plant coexistence, leading to low population densities and extinctions. In addition, positive feedbacks can allow locally stable forms of plant coexistence by inducing alternative stable states. Our findings highlight that the inclusion of plant-soil interactions may fundamentally alter the predictions on the structure and functioning of above-ground ecosystems. The scenarios presented in this study can be used to formulate hypotheses about the ways soil community effects may influence plant competition that can be tested with empirical studies. This will advance our understanding of the role of plant-soil feedback in ecological communities.

Grazing‐induced changes in plant–soil feedback alter plant biomass allocation

“…We found that plant–soil feedbacks were not related to plant community stability. This is in contrast to our final hypothesis that negative plant‐soil feedbacks increase vegetation dynamics, while positive plant–soil feedback increases vegetation stability (van der Putten and Peters 1997, Bever 2003, Revilla et al 2013). Plant communities were more stable in grazed than in ungrazed grassland plots, whereas plant–soil feedback effects were generally not different between grazing treatments (Fig.…”

“…As a result, plants will perform worse in soils where conspecific plants were abundant in the field (Mangan et al 2010). Finally, we hypothesized that spatiotemporal vegetation patterns become more dynamic if herbivores promote negative plant–soil feedback, because negative plant–soil feedback reduces the competitive ability of plants leading to increased species turnover (van der Putten and Peters 1997, Olff et al 2000, Bever 2003, Revilla et al 2013).…”

Using plant‐soil feedbacks to predict plant biomass in diverse communities

“…Second, PSFs must be comparable in size to differences in intrinsic growth rates among species to affect rank order abundance (Petermann et al 2008, Turnbull et al 2010, Revilla et al 2013, Sun et al 2014. We suggest several reasons that relatively large PSF effects will cause relatively small improvements in predictions of plant mass in communities.…”

Effects of soil microbes on plant competition: a perspective from modern coexistence theory

“…() to define an “interaction coefficient,” , whose sign is mathematically a necessary (but not sufficient) criterion for plant coexistence (Revilla et al. , Ke and Miki ). Bever et al.…”

“…Bever () added Lotka‐Volterra‐type density‐dependent plant competition to the original frequency‐based plant–soil feedback model; Revilla et al. () later analyzed this model and derived indexes corresponding to the original in Bever et al. ().…”