The context dependence of beneficiary feedback effects on benefactors in plant facilitation

Abstract

Summary Facilitative effects of some species on others are a major driver of biodiversity. These positive effects of a benefactor on its beneficiary can result in negative feedback effects of the beneficiary on the benefactor and reduced fitness of the benefactor. However, in contrast to the wealth of studies on facilitative effects in different environments, we know little about whether the feedback effects show predictable patterns of context dependence. We reanalyzed a global data set on alpine cushion plants, previously used to assess their positive effects on biodiversity and the nature of the beneficiary feedback effects, to specifically assess the context dependence of how small‐ and large‐scale drivers alter the feedback effects of cushion‐associated (beneficiary) species on their cushion benefactors using structural equation modelling. The effect of beneficiaries on cushions became negative when beneficiary diversity increased and facilitation was more intense. Local‐scale biotic and climatic conditions mediated these community‐scale processes, having indirect effects on the feedback effect. High‐productivity sites demonstrated weaker negative feedback effects of beneficiaries on the benefactor. Our results indicate a limited impact of the beneficiary feedback effects on benefactor cushions, but strong context dependence. This context dependence may help to explain the ecological and evolutionary persistence of this widespread facilitative system.

Facilitation among plants in alpine environments in the face of climate change

“…A recent global study in alpine regions evidenced that increasing cover of beneficiary species limited the reproductive output of associated nurse plants (Schöb et al, 2014b), suggesting that a possible increase in the growth rate of alpine beneficiary species because of warming (e.g., Pajunen et al, 2011) may have a negative impact on nurse plants, eventually being a possible cause of population extinction. However, another study observed a reduced negative effect of beneficiary species on nurse plants in more productive ecosystems (Schöb et al, 2014a), possibly indicating that in warmer, more productive environments, negative feedback effects of beneficiary species on nurse plants might diminish. From these seemingly contradictory viewpoints, understanding the feedback effects of beneficiary species on nurse plants in the face of climate change constitutes an important and challenging topic for the future.…”

The interplay between facilitation and habitat type drives spatial vegetation patterns in global drylands

“…Regular patterns are thought to be the consequence of competition operating at certain intermediate scales when compared with facilitation (Peter andElke 2005, von Hardenberg et al 2010). This result suggests that, in shrublands, the number of facilitated species is constraining the ability of nurses to increase patch sizes, probably because the more individuals are present in an area, the less they can grow (Schöb et al 2014). It is worth noting that separating direct facilitation effects from other co-occurrence mechanisms such as seed trapping or habitat sharing is challenging from observational data (Cipriotti andAguiar 2015, Delalandre andMontesinos-Navarro 2018).…”

Plant interactions with other organisms: molecules, ecology and evolution

“…A second case from a very different study system is the importance of context for beneficial interactions on facilitation effects in alpine cushion plants. Schöb et al . (pp.…”