title: Surface-water dynamics and land use influence landscape connectivity across a major dryland region.
abstract: Landscape connectivity is important for the long-term persistence of species inhabiting dryland freshwater ecosystems, with spatiotemporal surface-water dynamics (e.g., flooding) maintaining connectivity by both creating temporary habitats and providing transient opportunities for dispersal. Improving our understanding of how landscape connectivity varies with respect to surface-water dynamics and land use is an important step to maintaining biodiversity in dynamic dryland environments. Using a newly available validated Landsat TM and ETM+ surface-water time series, we modelled landscape connectivity between dynamic surface-water habitats within Australia's 1 million km2semiarid Murray Darling Basin across a 25-yr period (1987-2011). We identified key habitats that serve as well-connected "hubs," or "stepping-stones" that allow long-distance movements through surface-water habitat networks. We compared distributions of these habitats for short- and long-distance dispersal species during dry, average, and wet seasons, and across land-use types. The distribution of stepping-stones and hubs varied both spatially and temporally, with temporal changes driven by drought and flooding dynamics. Conservation areas and natural environments contained higher than expected proportions of both stepping-stones and hubs throughout the time series; however, highly modified agricultural landscapes increased in importance during wet seasons. Irrigated landscapes contained particularly high proportions of well-connected hubs for long-distance dispersers, but remained relatively disconnected for less vagile organisms. The habitats identified by our study may serve as ideal high-priority targets for land-use specific management aimed at maintaining or improving dispersal between surface-water habitats, potentially providing benefits to biodiversity beyond the immediate site scale. Our results also highlight the importance of accounting for the influence of spatial and temporal surface-water dynamics when studying landscape connectivity within highly variable dryland environments.
authors.affiliation: School of Biological, Earth & Environmental Sciences, University of New South Wales, Sydney, New South Wales, 2052, Australia.
authors.forename: Robbi
authors.identifier: 0000-0002-1533-2599
authors.initials: R
authors.lastname: Bishop-Taylor
authors.affiliation: School of Biological, Earth & Environmental Sciences, University of New South Wales, Sydney, New South Wales, 2052, Australia.
authors.forename: Mirela G
authors.initials: MG
authors.lastname: Tulbure
authors.affiliation: School of Biological, Earth & Environmental Sciences, University of New South Wales, Sydney, New South Wales, 2052, Australia.
authors.forename: Mark
authors.initials: M
authors.lastname: Broich
mesh_terms: D001315:Australia; D044822:Biodiversity; D003247:Conservation of Natural Resources / Q000379:methods*; D017753:Ecosystem; D005618:Fresh Water; D008962:Models, Theoretical; D012621:Seasons
keywords: Australia; Landsat; Murray-Darling Basin; flooding; graph theory; land use; landscape connectivity; protected areas; surface-water dynamics; wetlands