Robert A Preston

Publications of Robert A Preston

• Calculation of timber yields from North Queensland rainforests

  Authors: Robert A Preston, Jerome K Vanclay

  Jerome K Vanclay.

  Calculation of timber yields from north Queensland rainforests indicate that the long term average yield is in the vicinity of 63 000 cubic metres per year, and that an allowable cut of 60 000 cubicCalculation of timber yields from north Queensland rainforests indicate that the long term average yield is in the vicinity of 63 000 cubic metres per year, and that an allowable cut of 60 000 cubic metres per year should apply for the period 1986-1991. These calculations apply to the 158 000 hectares of Crown land managed for timber production between Townsville and the Daintree River. Estimates were prepared using cutting cycle analysis, and incorporated a number of innovations made possible by advances in computing technology. These included simulating the growth of individual plots rather than of stratum averages, and the use of a dynamic growth model which accommodated stand density, composition and site quality.

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• Utility of Landsat Thematic Mapper data for mapping site productivity in tropical moist forests

  Authors: Jerome K Vanclay, Robert A Preston

  Jerome K Vanclay.

  Regression analysis was used to develop a relationship between Landsat 5 Thematic Mapper data and site quality of permanent sample plots. The thermal band (6) produced misleading results, but theRegression analysis was used to develop a relationship between Landsat 5 Thematic Mapper data and site quality of permanent sample plots. The thermal band (6) produced misleading results, but the ratio of band 4 on 5 showed promise when combined with geological information. Best results were obtained when regression analysis was restricted to ensure that at least one each of the visible (1 to 3), mid-infrared (5 and 7) and near-infrared (4) bands were included. Results suggest that Landsat TM may be useful for mapping site quality in tropical moist forest in north Queensland. Interpolation of site productivity within a single pass seems feasible, but attempts to extrapolate results to other passes or to imagery obtained on different dates may be unreliable.

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• Sustainable Timber Harvesting in the Rainforests of North Queensland

  Authors: Jerome K Vanclay, Robert A Preston

  Simulation studies for an area of rainforest in north Queensland indicate that selection harvesting can provide a viable timber harvest in perpetuity. Rainforests are complex in terms of speciesSimulation studies for an area of rainforest in north Queensland indicate that selection harvesting can provide a viable timber harvest in perpetuity. Rainforests are complex in terms of species composition, tree age and size distribution, and topography. Efficient inventory procedures to overcome these special difficulties are described. The growth model employed in the calculations is dynamic, responding to changes in stand density, composition and management history. A harvesting simulator ensures reliable prediction of removals by selection logging, and predicts the effect on the residual stand. Yield calculations employed yield scheduling, a simulation approach which mimics the timing and location of logging operations. It produces a logging plan and a profile of predicted yields. The study area of 13 000 hectares sustained a yield of 4 900 cubic metres per annum throughout the 500 year simulation, indicating that selection logging is sustainable in north Queensland rain forests.

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