GROWEST PLUS: A tool for rapid assessment of seasonal growth for environmental planning and assessment

GROWEST PLUS is a software interface, designed to run a new version of the GROWEST plant growth index simulation model, originally developed by Fitzpatrick and Nix in 1970. The GROWEST model was designed to integrate the major climatic determinants of potential plant growth at broad geographic scales, and GROWEST PLUS allows comparisons of current conditions relative to historical variability. Substantive literature demonstrates the robustness, simplicity and application of GROWEST at regional to national scales. This has led the Bureau of Rural Sciences (BRS) to use this tool as one of a suite of analyses and models in the assessment of Exceptional Circumstances drought applications. The advantage of GROWEST is its simplicity. The model synthesises well established biological responses to seasonal trends in climate. It has the advantage of few dimensions, which significantly reduces computational and processing time. GROWEST performs well with the SGS Pasture Model outputs. In fact, GROWEST's performance is encouraging given the level of simplicity in the model. GROWEST, however, trades off some processes that are important at detailed scales in order to be able to run with readily available input variables for regional scale assessments. Unaccounted processes include detailed simulation of soil moisture, soil fertility and differences between phenological responses at the plant species level. GROWEST PLUS was developed by BRS and the Centre for Resource and Environmental Studies at the Australian National University. The most significant feature of GROWEST PLUS is its ability to analyse variability in seasonal growth over time using time-series outputs from the GROWEST model. For this purpose, the GROWEST model was comprehensively upgraded to run on weekly and monthly climate data, in point or grid form, to produce weekly and monthly outputs. This will have benefit in the analyses of specific events such as drought or the characterisation of growing season reliability for natural resource management. This paper demonstrates how users can easily and intuitively run the upgraded GROWEST model through the GROWEST PLUS graphical user interface, utilising 'real time' climate data, in point or grid form, to undertake a range of spatial and temporal analyses.