Functional assessment of animal interactions with shrub-facilitation complexes: a formal synthesis and conceptual framework.

Facilitation studies focus primarily on plants often neglecting the extended effects that cascade through ecological networks. Plants interact with other organisms through consumptive effects and a myriad of non-trophic effects such as habitat amelioration or pollination., Shrubs are a dominant benefactor species frequent in plant-facilitation studies but can also have direct and indirect interactions with animals. Herein, we use a systematic review to address the following two objectives: (i) to propose a conceptual framework that explores these interactions including the functional roles of the interacting species, and (ii) to quantitatively summarize the current state of this field examining effects beyond plant-plant interactions., To date, a relatively limited number of studies have examined the importance of coupled benefactor-subordinate plant positive interactions with animals (79 studies in total). From this set of studies, 36 studies documented positive plant interactions generating a total of 53 independent instances of either shrub-plant-animal or shrub-animal-plant interactions., These interaction pathways were evenly split between direct (49%) and indirect (51%) interactions of shrubs with animals. Hypotheses frequently tested included seed trapping, herbivore protection, magnet pollination and facilitation-mediated secondary seed dispersal. The most common functional role of shrubs was protection from herbivory, and the most common animal role associated with plant-facilitation complexes was that of a consumer., None of these studies explored bidirectional plant-animal interactions, used a network approach to describe the interaction sets, nor contrasted interaction strengths. Multitrophic, integrated sets of experiments incorporating plant facilitation into community dynamics are thus critical in advancing management of high-stress ecosystems wherein positive interactions are commonly reported. [ABSTRACT FROM AUTHOR]