Assessing the impact of regional natural resource management on land management and ground cover in the upper Maranoa River catchment

Assessing the impact of regional natural resource management on land management and ground cover in the upper Maranoa River catchment

Australian governments have invested nearly $10 Billion in Natural Resource Management (NRM) from 1983 to 2018. Despite this significant investment, there is an ongoing struggle to demonstrate investments have led to better land management.

Significant work has been done with remote sensing data to estimate seasonal groundcover for all parts of Queensland from 1990 onwards. A Dynamic Reference Cover Method (DRCM) was used in previous studies to minimise the climate signal
from these groundcover data to provide an indication of trends in land management.

This study used an adapted Dynamic Reference Cover Method to test the assumption that NRM investment led to improved grazing land management and groundcover. Climate and ground cover data were for the Upper Maranoa catchment in the
Queensland Murray-Darling Basin. The climate signal was reduced to indicate management impact on ground cover.

Groundcover scores indicated that grazing land management had improved across the catchment during the NRM investment period. The improvements, however, were not limited to or significantly different for NRM supported properties than for other properties in the catchment. Across the catchment, improvements in management, and therefore groundcover, were more significant during the Regional NRM investment period (2004-2017) than in the previous Landcare period (1990-2004).

Catchment modelling quantified reductions in soil loss and stream sediment loads due to improved management. Aspirational groundcover values associated with seasonal climate conditions were synthesised allowing improvements to be compared with 'what’s possible' across the catchment. It was found that the reduced stream sediment loads amounted to 10% of what is possible during the Landcare period and a further 15% during the Regional NRM investment period. This suggests that improved management since 1990 has led to 25% of the maximum possible reductions in stream sediment load from hillslope erosion in grazing lands in the Upper Maranoa catchment.

Participating landholders were interviewed and some enablers and barriers to change were identified for consideration in supporting sustainable grazing landscapes. Information and networking associated with NRM activities has enhanced knowledge and grazing land management. Climate, markets, cash flow, changes of ownership and vegetation legislation represent ongoing challenges to implementing better management practices.

The adapted DRCM showed value in its potential to reduce the climate signal from ground cover data. Identification of an unimpacted area, or control, was found to be a significant restraint in using the adapted DRCM to evaluate the NRM investment. The method showed capacity for retro analysis of ground cover from existing remote sensing programs to evaluate land management and current or previous program outcomes.