A framework for simulating agroforestry options for the low rainfall areas of Australia using APSIM

The long-term benefits of retaining or planting trees on farms to rehabilitate land and protect the soil from erosion or salinity problems has to be traded off against the impact of tree competition on commercial crops, especially in the medium to low rainfall regions of Australia. The incentive to plant trees would increase if tree competition could be offset by economic returns gained from farm forestry products and by the beneficial impacts of tree windbreaks on crop yields and resource sustainability. The Agricultural Production Systems Simulator (APSIM) has a well-established capability to simulate cropping systems and this paper reports on progress in applying APSIM to agroforestry systems in order to quantify the potential benefits and risks of planting trees as windbreaks to cropping land in Australia. A simple case study indicating one possible model configuration is used to demonstrate this emergent capability for simulating tree and crop productivity and their interactions. The simulated agroforestry system consisted of the growth of a belt of trees (Eucalyptus argophloia) positioned as a windbreak on the edge of a field where a crop of winter chickpea (Cicer arietinum L.) is grown over a 30-year period. The example simulations quantify the yield and economic returns of annual chickpea crops in addition to the discounted economic return from timber production after 30 years of tree growth. This example demonstrates how APSIM can be used to quantify the economic tradeoffs in planting trees as windbreaks on a commercial farm in a low rainfall region of Australia. Crown Copyright (C) 2002 Published by Elsevier Science B.V. All rights reserved.