Long-term monitoring and modelling of pasture regeneration and water quality from a Bothriochloa pertusa site in the Great Barrier Reef catchments

There has been considerable investment in grazing land management Australia’s Great Barrier Reef catchments targeted at improving off-site runoff and water quality. This study used a systems modelling framework to analyse an 18-year monitoring data set from Indian couch (Bothriochloa pertusa) dominated hillslope flume site the Burdekin catchment, Australia. The analyses show important functional differences B. pertusa pastures, relative native tussock pastures they replaced, with implications for how are monitored managed: (1) rates of landscape recovery were far slower than degradation. In practical time frames most managers, transition state is effectively irreversible, so historical practices will have adapt; (2) transformations pasture composition structure can lead misinterpretation trends ground cover (a common proxy condition). At 50% cover, only 33% biomass local pastures. Where invasions occurring, inferences positive associations between changes function break down: increases instead be accompanied by decreases biomass, productivity, retention. paper contributes initial calibration GRASP model transformed site, capturing observed relationships management, serves as starting point which these landscapes, growing extent concern catchments, better represented assessments, revised options explored. calibrated was able accurately represent long-term average sediment yield (both within 2% observed) but adequately year-to-year variation (not sediment).