Large frugivorous birds facilitate functional connectivity of fragmented landscapes

Abstract

Summary1. Quantifying ecosystem functions in spatially explicit ways is important for management decisions in increasingly fragmented landscapes. Between-patch dispersal of seeds by frugivores constitutes a key ecosystem function to ensure connectivity for fleshy-fruited plants. However, to date, methodological hurdles have limited our understanding of dispersal pathways on the landscape scale. 2. We made use of newly available tracking devices and combined movement data of 30 trumpeter hornbills Bycanistes bucinator with gut passage times and high-resolution habitat data in a fragmented forest landscape in South Africa. We identified each potential seed dispersal path and distinguished whether potential seed transport happened to a different forest patch (between-patch dispersal), within the same patch (within-patch dispersal) or into the habitat matrix (failed dispersal). To quantify functional landscape connectivity, we identified all possible between-patch connections and used graph networks to estimate landscape connectivity provided by hornbills. 3. Although potential between-patch dispersal events were rare (on average 7% compared to 20% failed dispersal and 73% within-patch dispersal), hornbills could cover distances of up to 15 km. Hornbills visited over 100 forest patches and connected a habitat network with an extent of about 50 km, which increased the potential functional connectivity of the landscape more than twofold. 4. We identified habitat patches that were critical stepping stones for seed dispersal pathways. Without these stepping stones, the network would likely disintegrate into separated components and lead to isolation of forest fragments. 5. Synthesis and applications. We showed that large frugivorous birds can greatly improve functional connectivity for fleshy-fruited plants across broad scales, linking habitat patches in fragmented forest landscapes. Combining high-resolution movement and landscape data in graph networks allows identifying seed dispersal pathways and critical stepping stones in fragmented landscapes. This approach addresses the general challenge of spatially explicit mapping of ecosystem services and can be widely incorporated in reserve design and landscape-level conservation planning.

Active restoration facilitates bird community recovery in an Afrotropical rainforest

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Morphological trait matching shapes plant–frugivore networks across the Andes

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Assessing bias and knowledge gaps on seed ecology research: implications for conservation agenda and policy

“…We studied geographic, phylogenetic and functional group biases in traits related to the ecology of seeds because knowledge on seed ecology is key to the understanding of species niche breadth and geographic distribution (Donohue et al 2010), community assembly (Schleuning et al 2015), and responses to global change drivers such as invasive species, climate change and forest fragmentation (Walck et al 2011, Driscoll et al 2014, Mueller et al 2014, Hudson et al 2015.…”