Brigalow trees compete with crops for water and nutrients.
Recovering biodiversity and promoting sustainable agriculture in the Queensland Brigalow Belt
Dr Melanie Bradley undertook doctoral research in the southern Queensland Brigalow Belt, to investigate opportunities for integrating brigalow vegetation with dryland cropping.
17 March 2009 | Updated 14 October 2011
Native brigalow vegetation coverage has been reduced by more than 90 per cent in the Queensland Brigalow Belt, leading to concerns about land and water degradation and biodiversity loss.
Potential exists for avoiding resource degradation, recovering biodiversity and promoting sustainable agriculture, by deliberately integrating regrowth and mature stands of brigalow vegetation with dryland cropping systems.
During 2003–06 Dr Melanie Bradley completed a Doctorate project in the southern Queensland Brigalow Belt, to look at different aspects of integrating brigalow conservation with cropping.
The research was supported by CSIRO and Griffith University, Queensland, Australia. It investigated:
tree-crop competition – to calculate the yield loss that occurs when trees are retained in an agricultural landscape
soil chloride profiles under annual cropping and brigalow vegetation – to discover whether deep drainage had increased and chloride leaching had occurred, following land-clearing
- the biodiversity values of regrowth and mature brigalow vegetation – to determine effective ways of promoting biodiversity recovery.
“The best ecological and economic outcomes will be achieved by retaining both regrowth and mature brigalow vegetation in the landscape.”
Dr Melanie Bradley, CSIRO
wheat yields in the competition zone were reduced, on average, by 46–98 per cent, compared to wheat yields in the open paddock (i.e. the area beyond the influence of the trees)
future research should investigate how land management practices, climatic conditions, vegetation clearing and cropping history, impact on tree-crop competition.
Soil chloride and deep drainage
higher soil chloride levels were measured under brigalow vegetation, in comparison to the levels measured under cropping, providing evidence that deep drainage had increased and chloride had leached, following land clearing
Biodiversity values of brigalow vegetation
Native vegetation planning and management should consider the needs and values of landholders, property or catchment size, and the position of important landscape features (salinity recharge/discharge areas, other areas of brigalow habitat).
Optimal outcomes are likely to be achieved by retaining a mixture of regrowth and mature brigalow vegetation in the landscape.
This will provide a range of habitats for plants and animals, assist with minimising salinity risk, and help to lessen adverse impacts on agriculture.
Read more about Sustainable agricultural landscapes.