High Conservation Value of Forest Fragments for Plant and Frugivore Communities in a Fragmented Forest Landscape in South Africa

Abstract

Fragmentation is a major threat factor for plant–frugivore communities in tropical and subtropical forests. Resulting changes in the distribution of traits within these communities, e.g., a loss in large‐bodied frugivores, may lead to strong changes in plant–frugivore interactions in fragmented forests. Yet, we still lack a thorough understanding of the interplay between forest fragmentation, the trait‐composition of communities and resulting plant–frugivore interactions on a community‐scale. In a fragmented South African landscape comprising different forest categories—i.e., continuous natural forest, forest fragments surrounded by natural grassland, and forest fragments surrounded by sugarcane—we investigated the relationship between communities of fruiting plants and their frugivore visitors in response to forest fragmentation, as well as the interactive effects of forest fragmentation and fruit size of the plants on the number of frugivore visitors and their body size. Neither the fruit size of plant nor the body mass of frugivore communities differed between natural forest sites and forest fragments. Moreover, in‐depth analyses of frugivore assemblages visiting plant species revealed no effect of forest category on the number of frugivore visits or their mean body mass. The number of visits and body mass of frugivores were merely determined by the crop and fruit size of the focal plant species. Overall, our results suggest that frugivory of plant species with differently sized fruits was not reduced in forest fragments. Thus, fragments with high fruit availability may be key elements maintaining the functional connectivity of a heterogeneous forest landscape.

Toucans (Ramphastos ambiguus) facilitate resilience against seed dispersal limitation to a large‐seeded tree (Virola surinamensis) in a human‐modified landscape

“…In general, our results support the idea that limiting hunting on key seed dispersers and maintaining landscape heterogeneity can preserve the integrity of plant–animal interactions between large‐seeded plants and large‐bodied frugivores in human‐modified landscapes (Berens et al . ). The persistence of large‐seeded tree interactions with their seed dispersers in disturbed habitats is also associated with seed disperser's traits: large‐seeded trees mainly dispersed by non‐hunted avian seed dispersers may be more resilient than those that depend on terrestrial/arboreal seed dispersers.…”

“…Despite continued landscape degradation in tropical areas, an increasing number of studies find some species of large-bodied vertebrates can tolerate and persist under moderate to high levels of forest disturbance (Neuschulz et al 2013, Lindsell et al 2015. As such, the integrity of plant-seed disperser interactions may be maintained, including seed dispersal of large-seeded plants (Berens et al 2014). This evidence highlights the need for further research on the effect of anthropogenic landscapes on the seed dispersal ecology of plants, especially on vulnerable plant groups, such as large-seeded plants (Cramer et al 2007).…”

“…As such, the integrity of plant–seed disperser interactions may be maintained, including seed dispersal of large‐seeded plants (Berens et al . ). This evidence highlights the need for further research on the effect of anthropogenic landscapes on the seed dispersal ecology of plants, especially on vulnerable plant groups, such as large‐seeded plants (Cramer et al .…”

Conservation of the Ethiopian church forests: Threats, opportunities and implications for their management

“…Spatially targeted expansion of such buffer zones and establishment of new forest patches within the matrix located at distances compatible with dispersal distances of trees may play an important role in increasing the quality of the matrix (see e.g. Lemenih and Bongers 2010;Telila et al 2015), thereby decreasing the functional isolation of species' populations within a network of forest patches and reducing the risks of extinction (Vandermeer and Carvajal 2001;Berens et al 2014).…”

“Conservation value”: a review of the concept and its quantification

“…) and are key in the maintenance of functional connectivity within heterogeneous landscapes (Berens et al. ). This connectivity concept has also been applied to individual elements within the landscape, such as trees, if they act as stepping stones for bird populations' movement (Fischer and Lindenmayer ).…”