Assessment and monitoring of foliage projected cover and canopy height across native vegetation in Queensland, Australia, using laser profiler data

The aim of this project was to demonstrate the potential of laser profiling for monitoring forest structure. Data were captured from flights at 30, 60, and 100 m above the canopy over three study sites in south-east Queensland at regular intervals over a 2-year period. Field measurements of foliage projected cover (FPC) and tree height were found to be highly correlated with laser derived estimates (R-2 from 0.91 to 0.95). Monitoring of changes in FPC and tree height, as a result of logging or growth, was also successful. Tree heights, in particular, were measured accurately over time (residual standard error (RSE) of 0.45 m). The large RSE of the FPC model (from 5.7% to 7.3% FPC) means that subtle changes, such as seasonal variation, may be difficult to monitor. Flying height was found to be a significant explanatory variable in estimating field FPC. A transect of greater than 1000 km was also flown in a single helicopter pass to assess the technology over a range of forest types. Field measurements of FPC were collected for 21 sites along this transect. Strong relationships were observed between laser and field FPC, but these varied with forest type.