Large frugivorous birds facilitate functional connectivity of fragmented landscapes

1. 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.publishe

Range size: Disentangling Current Traits and Phylogenetic and Biogeographic Factors

The range size of a species can be determined by its current traits and by phylogenetic and biogeographic factors. However, only rarely have these factors been studied in combination. We use data on the geographic range sizes of all 26 Sylvia warblers to explicitly test whether range size was determined by current species-specific traits (e.g., body size, dispersal ability), phylogenetic factors (e.g., age of the lineage), or environmental, biogeographic factors (e.g., latitudinal position of the range). The results demonstrated that current traits and phylogenetic and biogeographic factors were interrelated. While a number of factors were significant in simple regression analyses, only one factor determined range size in the multiple regression analyses - dispersal ability. Species with better dispersal ability had larger ranges than species with poorer dispersal ability. Apparent increases of range size with latitude or with the age of the species resulted from correlations with dispersal ability. While the most significant factor that influences the range size of a group of species might differ from one group to the next, these results demonstrate that studies that focus only on a single, for example, phylogenetic, factor might yield misleading results

Seed-dispersal distributions by trumpeter hornbills in fragmented landscapes

Frugivorous birds provide important ecosystem services by transporting seeds of fleshy fruited plants. It has been assumed that seed-dispersal kernels generated by these animals are generally leptokurtic, resulting in little dispersal among habitat fragments. However, little is known about the seed-dispersal distribution generated by large frugivorous birds in fragmented landscapes. We investigated movement and seed-dispersal patterns of trumpeter hornbills (Bycanistes bucinator) in a fragmented landscape in South Africa. Novel GPS loggers provide high-quality location data without bias against recording long-distance movements. We found a very weakly bimodal seed-dispersal distribution with potential dispersal distances up to 14.5 km. Within forest, the seed-dispersal distribution was unimodal with an expected dispersal distance of 86 m. In the fragmented agricultural landscape, the distribution was strongly bimodal with peaks at 18 and 512 m. Our results demonstrate that seed-dispersal distributions differed when birds moved in different habitat types. Seed-dispersal distances in fragmented landscapes show that transport among habitat patches is more frequent than previously assumed, allowing plants to disperse among habitat patches and to track the changing climatic conditions

The first virtual Compton scattering experiment at MAMI

Virtual Compton scattering, i.e. the exclusive reaction gamma *p to gamma 'p' with gamma * denoting a virtual photon, provides new insights on the internal structure of the proton. Below pi /sup 0/ production threshold, this experiment measures the generalized polarizabilities of the proton as defined by Guichon and Drechsel. These new electromagnetic observables, functions of Q/sup 2/, enlarge the concept of electric ( alpha ) and magnetic ( beta ) polarizabilities in real Compton scattering (Q/sup 2/=0). The first VCS experiment of this kind was measured at the three spectrometer facility at the Mainz Microtron MAMI for Q/sup 2/=0.33 GeV/sup 2/ and we present in this paper the preliminary results

Real and Virtual Compton scattering (experiments).

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