Hydrological and land use determinants ofEucalyptus camaldulensisoccurrence in floodplain wetlands

Abstract

Hydrological and land use changes can affect species in human altered landscapes. Typically the impacts of hydrological and land use changes are examined separately, with hydrological determinants used to explain the distribution of species in water dependent and aquatic habitats and land use factors used to examine terrestrial species. However, given the connectedness of aquatic and terrestrial habitats, stressors originating in one domain may be important in the other. To explore the importance of integrating both hydrological and land use factors, we tested the relative contribution of hydrological factors and land use context as determinants of the dominant riparian tree species, Eucalyptus camaldulensis Dehn. throughout wetlands of the Condamine catchment, southern Queensland, Australia. The occurrence of E. camaldulensis was modelled against hydrological and land use factors using generalized linear models (GLMs) and validated using internal bootstrapping procedures. Validated models which included both hydrological (distance from weir, wetland–river connectivity and groundwater depth)and land use factors (agricultural land cover and grazing intensity) performed better than those developed using only hydrological factors. The study results highlight the importance of an integrated perspective which considers both hydrological and land use factors in order to understand occurrence patterns of riparian and floodplain tree species in a range of settings. This approach could be especially important when assessing changes to hydrology and land use which may be triggered by climatic changes.