4SPaM: a process-based and weather-driven population model for managing weeds in temperate pastures

摘要

The four Species Pasture Model (4SPaM) has been developed by the CRC for Weed Management Systems (CRCWMS) to analyse the ecological and economic impacts of management strategies against pasture weeds across temperate Australia. Weeds dominate pastureby outcompeting desirable species within the grazing environment. Existing pasture productivity models such as GrassGro~(TM), are not designed to accurately simulate weed management scenarios. Between-species interactions are not simulated in sufficientdetail to produce confident projections of plant community dynamics. The complex competitive interactions in multi-species pasture, when the aims are both to suppress the weeds and to augment the desirable pasture components, makes single optimal pasturemanagement solutions unobtainable. Integrated weed management options, climate, soil fertility, and initial sward composition all interact in complex ways, which are hard to comprehend without the aid of a dynamic system model that simulates these factors. 4SPaM is a modular process-based ecological model that includes four main functional plant groups commonly found in temperate pastures (annual grass weed, perennial grass, annual broadleaf weed and annual legume), weather, soil fertility, herbicide applications, hay and silage-cutting, and sheep flock management. 4SPaM simulates the state of the pasture, sheep flock and gross-margins, and will be loose-coupled to a dynamic programming economic model to identify optimal management technologies and their benefits for each climatic location. The model is being tested using the outcomes of field trials, and when reliably calibrated will provide a vehicle aimed at expanding the applicability of IWM solutions Australia-wide.