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Evaluation of the risks of land and pasture degradation associated with drought

Day, K.A. Mr; Ph: (07) 3896 9576; Fax: (07) 3896 9843; mailto:DayKA@dnr.qld.gov.au

Research organisations: Climate Impacts and Grazing Systems Group, Department of Natural Resources, 80 Meiers Road, Indooroopilly, Qld 4068; Beef Division, Queensland Department of Primary Industries, PO Box 118, Gayndah Qld 4625

Sponsors: RIRDC, Rural Industries Research and Development Corporation

Objective: The project aimed to develop a system to calculate the risks of land and pasture degradation on a Local Government Area scale such that degradation 'outlooks' or 'alerts' could be issued each season. Queensland was chosen as a case study to produce an operational system.

Methodology: Surveys of Queensland's native pastures conducted in 1991 indicated that approximately 40 per cent of the state was in a deteriorating condition and 20 per cent was degraded. Previous research had shown that the major degradation processes resulted in loss of soil and desired perennial grass species. The major processes were driven by heavy utilisation during drought periods. Thus degradation could be reduced by early warning of heavy utilisation i.e. high stock numbers relative to pasture growth. To address these problems, we proposed that an operational simulation model of pasture growth would allow near real time calculation of the two major indicators of degradation risk, i.e. pasture utilisation and surface cover.

Progress:

1. A general model of native pasture growth was parameterised for major native pasture communities in Queensland and validated successfully for below average-rainfall conditions;

2. Specific pasture community models for perennial grass basal cover and standing pasture yield were developed from grazing trials allowing simulation of surface cover and dynamic plant density as a function of utilisation;

3. The safe stocking rates, which were estimated by graziers across a wide range of environments and pasture productivity , were shown to actually represent a relatively narrow range of average annual utilisation i.e. 15-25 per cent consumption of pasture growth;

4. A near real time model was developed and comprehensively evaluated in a parallel project including the development of a national prototype (National Drought Alert Strategic Information System QPI20, LWRRDC). Since the completion of this project, this operational system has been modified to provide drought and degradation alerts at an LGA scale for Queensland. This product is currently under evaluation and will be available on the World Wide Web in early 1999.

Period: starting date 1992-01; completion date 1995-12

Status: completed

Keywords: Drought, pasture degradation, early warning, models

Publications:

 Day, K.A., and Philp, M.W. (1997). Swiftsynd: a methodology for measuring a minimum data set for calibrating pasture and soil parameters of the pasture growth model GRASP. In Evaluating the risks of pasture and land degradation in native pastures in Queensland, edited by K.A. Day, G.M. McKeon and J.O. Carter. Final report for Rural Industries Research and Development Corporation project DAQ-124A.

Day, K.A., McCaskill M.R. and McKeon G.M. (1997). A review of pasture production data in Queensland. In Evaluating the risks of pasture and land degradation in native pastures in Queensland, edited by K.A. Day, G.M. McKeon and J.O. Carter. Final report for Rural Industries Research and Development Corporation project DAQ-124A.

Day, K.A., McKeon, G.M. and Carter, J.O. (1997). Evaluating the risks of pasture and land degradation in native pastures in Queensland. Final Report for the Rural Industries Research and Development Corporation project DAQ-124A.

Littleboy, M. and McKeon G.M. (1997). Subroutine GRASP: Grass Production Model. In Evaluating the risks of pasture and land degradation in native pastures in Queensland, edited by K.A. Day, G.M. McKeon and J.O. Carter. Final report for Rural Industries Research and Development Corporation project DAQ-124A.

 

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