Disentangling habitat capacity from dendritic connectivity in river-like landscapes
Abstract
Habitat fragmentation and land use changes are causing major biodiversity losses. Connectivity of the landscape or environmental conditions alone can shape biodiversity patterns. In nature, however, local habitat characteristics are often intrinsically linked to a specific connectivity. Such a link is evident in riverine ecosystems, where hierarchical dendritic structures command related scaling on habitat capacity. We experimentally disentangled the effect of local habitat capacity (i.e., the patch-size) and dendritic connectivity on biodiversity in aquatic microcosm metacommunities by suitably arranging patch-sizes (Riverine, Random and Homogeneous, fig. 1) within river-like networks. By measuring species' persistence and species' density we followed diversity patterns in terms of alpha-, beta-, gamma-diversity (local species richness, among-community dissimilarity and regional species richness), and community evenness in the above landscape configurations. Overall, more connected communities that occupy a central position in the network exhibited higher species richness, irrespective of patch-size arrangement. High regional evenness in community composition was found only in landscapes preserving geomorphological scaling properties of patch-sizes. In these landscapes, some of the rarer species sustained regionally more abundant populations and were better able to track their own niche requirements compared to landscapes with homogeneous patch size or landscapes with spatially uncorrelated patch size. Altering the natural link between dendritic connectivity and patch-size strongly affects community composition and population persistence at multiple scales. All the experimental results were supported (and extended by) a theoretical analysis where the above mechanisms have been generalized. Spatial configuration of dendritic networks and corresponding patch-sizes in the microcosm experiment. (A) Riverine landscapes (blue) preserved the observed scaling properties of real river basins; (B) Random landscapes (red) had the exact values of volumes as in the Riviverine landscapes, randomly distributed across the networks; (C), in homogeneous landscapes (green) the total volume of the whole metacommunity was equally distributed to each 36 local communities. Patch-size (size of the circle) is scaled to the actual medium volume.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFM.B13D0537C
- Keywords:
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- 0410 BIOGEOSCIENCES Biodiversity;
- 0483 BIOGEOSCIENCES Riparian systems;
- 1813 HYDROLOGY Eco-hydrology;
- 1825 HYDROLOGY Geomorphology: fluvial