Perceptions of weeds in changing contexts. Land-use change, landscape value change and climate change in south-eastern Australia: adaptation to change in the third century of the timeless land
Ian Mansergh, Climate Change Adaptation, Department of Sustainability and Environment, PO Box 500, East Melbourne, Victoria 3002, Australia.
To perceive a weed is to ascribe meaning to the landscape where it occurs and ecosystem services required from that landscape. These perceptions change over time. In Australia, native vegetation has been transformed from something to be cleared to something of intrinsic value, and landscapes from bare palettes for new agronomy species to landscapes needing strict continental quarantine. We can now conceive of environmental weeds. Amidst these trends, the effects of global warming provide novel, all pervasive, pressures of environmental change at the continental scale. Under global climate change, southeastern Australia faces a warmer, drier, extreme-weather-event punctuated (e.g. fire and flood) future, whilst inhabitants face a socio-ecological-economic future that is both water and carbon-constrained and landscapes with profound legacies.
Biophysical environments and related processes are changing, and will continue to change, including abundances and distributions of biota, including weeds. Prospective biological responses of weedy species provide part of our understanding, however, socio-ecological landscape changes, frequently ignored, are vital for a more complete appreciation of appropriate long-term responses. In the context of multiple uncertainties, adaptation to climate change, including land-use and management, is an increasing societal focus. Adaptation to climate change is vital for long-term sustainability and intergenerational landscape equity and includes the resilience of agricultural and post agricultural landscapes.
Perceptions of assets and ecosystem services that we value and obtain from landscapes are changing trajectories of land-use, and response to climate change may accelerate these processes (e.g. carbon sequestration). Adaptation and mitigation (of CO2 emission) strategies converge in landscapes as society seeks to increase its resilience to climate change impacts. This contribution examines the interaction of these major fluxes in relation to historic land use and our perception of weeds. Responses to climate change will accelerate Australian society's on-going re-evaluation of landscapes and services they provide, including reevaluation of 'weeds' and consequent management strategies.