Alluring restoration strategies to attract seed‐dispersing animals need more rigorous testing

Abstract

In a recently published paper, Silva et al. conclude that placing fruit feeders (induced seed dispersal) in restored tropical forests serves to enrich the diversity of animal species and seeds in recovering forests and therefore is a cost‐effective tropical forest restoration strategy. We argue that due to poor experimental design and choice of response variables measured, the data presented do not provide rigorous support that induced seed dispersal enhances tropical forest recovery. The authors present data on animal visitation to two fruit feeders in a single 7‐year old restoration site in the Brazilian Atlantic forest over a 2‐year period. Their study has no replication and lacks no‐intervention controls with which to compare the effect of this restoration strategy. These experimental design shortcomings prevent them from demonstrating the efficacy of fruit feeders for attracting animals or enriching vegetation recovery. Like many faunal attraction studies, Silva et al. (2020) do not present any data on seedling recruitment; such data are needed to demonstrate that restoration strategies enhance vegetation recovery. Nor do they provide cost estimates for induced seed dispersal as compared to other empirically supported restoration strategies. Synthesis and applications. Promoting enticing restoration methods to attract animals into a restoration site without rigorous data to support the value added of such strategies for enhancing faunal abundance and forest vegetation recruitment has the potential to misguide the investments of scarce restoration resources. We recommend standards for evaluating novel restoration methods to determine whether they are cost‐effective approaches to include in the diverse toolbox needed to meet ambitious global forest restoration targets.

Pioneers of post‐agricultural forest successions are adapted for herbivory avoidance but not biotic seed dispersal

“…Large‐scale mammalian predator control or eradication might increase the dispersal of fleshy‐fruited native tree species through enhanced frugivory (Carpenter et al, 2018; Bombaci et al, 2021), potentially establishing a virtuous cycle in which enhanced frugivory accelerates forest restoration — which in‐turn increases frugivorous bird habitat. However, enhanced frugivory does not guarantee increased colonisation rates since frugivore habitat use patterns and local site factors, including mammalian herbivory, may severely limit establishment rates during post‐agricultural forest successions (Holl, 1998; Holl et al, 2022). Implementing experimental treatments to enhance seed dispersal (such as installing artificial perches or promoting pioneer woody species cover; McClanahan & Wolfe, 1993; Holl, 1998; Reay & Norton, 1999) in a factorial design with mammalian herbivore exclusion across a national network of experimental sites would provide robust evidence on the relative benefits of either management intervention for post‐agricultural forest successions.…”

Feedback loops drive ecological succession: towards a unified conceptual framework

“…In tropical forests, for instance, fruiting trees of the genus Ficus often attract a wide diversity of bats, birds and mammals, which can promote the assembly of more diverse seedling communities later in succession relative to locations without fig trees (de la Peña‐Domene, Martinez‐Garza & Howe, 2013; Cottee‐Jones et al ., 2016). This priority effect is often an important consideration in ecological restoration strategies, and restoration practitioners often select species for active seeding or planting based on their perceived attractiveness to pollinators or dispersers (Menz et al ., 2011; Jones & Davidson, 2016; Holl, Joyce & Reid, 2022).…”

Feedback loops drive ecological succession; towards a unified conceptual framework

“…In tropical forests, for instance, fruiting trees of the genus Ficus often attract a wide diversity of bats, birds and mammals, which can promote the assembly of more diverse seedling communities later in succession relative to locations without fig trees (de la Peña-Domene, Martinez-Garza & Howe, 2013;Cottee-Jones et al, 2016). This priority effect is often an important consideration in ecological restoration strategies, and restoration practitioners often select species for active seeding or planting based on their perceived attractiveness to pollinators or dispersers (Menz et al, 2011;Jones & Davidson, 2016;Holl, Joyce & Reid, 2022).…”