Landscape moderation of biodiversity patterns and processes - eight hypotheses

Authors: TSCHARNTKE, TEJA - University Of Gottingen; TYLIANAKIS, JASON - Canterbury Christchurch College; Rand, Tatyana; DIDHAM, RAPHAEL - University Of Western Australia; FAHRIG, LENORE - Carleton University - Canada; BATARY, PETER - University Of Gottingen; BENGTSSON, JANNE - Swedish University Of Agricultural Sciences; CLOUGH, YANN - University Of Gottingen; CRIST, THOMAS - Miami University - Ohio; DORMANN, CARSTEN - Helmholtz Centre

Submitted to: Biological Reviews
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/14/2011
Publication Date: 8/1/2012
Citation: Tscharntke, T., Tylianakis, J.M., Rand, T.A., Didham, R.K., Fahrig, L., Batary, P., Bengtsson, J., Clough, Y., Crist, T.O., Dormann, C.F. 2012. Landscape moderation of biodiversity patterns and processes - eight hypotheses. Biological Reviews. 87(3): 661-685. DOI: 10.1111/j.1469-185X.2011.00216.x.

Interpretive Summary: Understanding how landscape characteristics (i.e. the pattern and composition of habitats in the landscapes surrounding a local habitat) affect local biodiversity patterns and ecological processes is critical for mitigating effects of global environmental change. In this review, we use knowledge gained from human-modified landscapes to suggest the following seven hypotheses, which we hope will encourage a systematic research approach on the role of landscape composition and configuration in determining the structure of ecological communities, ecosystem functioning and services. (1) The dominance of beta diversity hypothesis: dissimilarity of local communities across the landscape determines landscape-wide biodiversity and overrides negative local effects of habitat fragmentation on biodiversity. (2) The landscape species pool hypothesis: local biodiversity is influenced predominantly by the size of the landscape-wide pool of species. (3) The intermediate landscape-complexity hypothesis: effectiveness of local conservation management is highest in structurally simple, rather than in cleared (i.e. extremely simplified) or in complex landscapes (e.i. those with a high proportion of natural habitats). (4) The landscape-moderated insurance hypothesis: landscape complexity provides spatial and temporal insurance, i.e. rapid return of a system to its original state post disturbance, and stability of patterns and processes in changing environments. (5) The cross-habitat spillover hypothesis: spillover of energy, resources and organisms across habitats, including between managed and natural ecosystems, influences landscape-wide community structure and associated processes. (6) The landscape-moderated concentration and dilution hypothesis: spatial and temporal changes in landscape composition can cause transient concentration or dilution of populations and the intensity of associated interactions (i.e. pollination and biological control). (7) The landscape-moderated trait and functional-group selection hypothesis: landscape structure drives the selection of particular species traits and functional groups, shaping the trajectory of community assembly. Shifting our research focus from local to landscape-moderated effects on biodiversity will be critical to developing solutions for future biodiversity and ecosystem service management.

Technical Abstract: Understanding how landscape characteristics affect local biodiversity patterns and ecological processes is critical for mitigating effects of global environmental change. In this review, we use knowledge gained from human-modified landscapes to suggest the following seven hypotheses, which we hope will encourage a systematic research approach on the role of landscape composition and configuration in determining the structure of ecological communities, ecosystem functioning and services. (1) The dominance of beta diversity hypothesis: dissimilarity of local communities across the landscape determines the landscape-wide biodiversity and overrides negative local effects of habitat fragmentation on biodiversity. (2) The landscape species pool hypothesis: local biodiversity is influenced predominantly by the size of the landscape-wide species pool. (3) The intermediate landscape-complexity hypothesis: effectiveness of local conservation management is highest in structurally simple, rather than in cleared (i.e. extremely simplified) or in complex landscapes. (4) The landscape-moderated insurance hypothesis: landscape complexity provides spatial and temporal insurance, i.e. high resilience and stability of patterns and processes in changing environments. (5) The cross-habitat spillover hypothesis: spillover of energy, resources and organisms across habitats, including between managed and natural ecosystems, influences landscape-wide community structure and associated processes. (6) The landscape-moderated concentration and dilution hypothesis: spatial and temporal changes in landscape composition can cause transient concentration or dilution of populations and functional effects. (7) The landscape-moderated trait and functional-group selection hypothesis: landscape structure drives the selection of particular species traits and functional groups, shaping the trajectory of community assembly. Shifting our research focus from local to landscape-moderated effects on biodiversity will be critical to developing solutions for future biodiversity and ecosystem service management.