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Primary Production Landscapes of Victoria

Richard MacEwan1, Nathan Robinson1, Mark Imhof2, David Rees2, Victor Sposito3, Monique Elsley3

1Department of Primary Industries, Box 3100, Bendigo Delivery Centre, VIC 3554. Email: Richard.MacEwan@dpi.vic.gov.au, Nathan.Robinson@dpi.vic.gov.au
2
Department of Primary Industries, 621 Sneydes Rd, Werribee, Vic 3030. Email: Mark.Imhof@dpi.vic.gov.au, David.Rees@dpi.vic.gov.au
3
Department of Primary Industries, 32 Lincoln Square North, Carlton, 3053. Email: Victor.Sposito@dpi.vic.gov.au, Monique.Elsley@dpi.vic.gov.au

Abstract

Six regional ‘primary production landscapes’ (PPL) comprising twenty two sub-regions are described for Victoria. This spatial hierarchy provides a regional platform from which to explore climate change and climate variability impacts on agricultural industries, management practices and soils. This paper provides a simple summary of the proposed landscape units and an example for the Northern Plains PPL.

Key Words

Agro-ecological zones, climate change, climate variability

Introduction

The Victorian landscape exhibits a rich variety of terrestrial ecosystems (see for example a map of pre-1750s vegetation or the Victorian bioregions, Figure 1). This variety is a result of diverse terrain (from the mountains to the plains), climate (alpine to semi-arid), geology and soils. Agriculture has adapted to this diversity, giving rise to differences in land use and management practices around the state in response to rainfall, seasonal temperature conditions, availability of irrigation water, and soil quality.

Figure 1. Simplified pre-1750 native vegetation of Victoria (Department of Sustainability and Environment 2004).

Over the last fifty years, land use practices have become relatively finely-tuned to climate and soil. Although climate over that period has been highly variable with respect to droughts, good years and wet years, models of the future climate are showing a general shift to drier and hotter conditions.

There are many important questions for the future of Victorian agriculture and its adaptation to changing climatic conditions. For example:

  • How might this predicted climate change affect the current distribution of land use?
  • Will practices within a particular land use have to change?
  • Will some land uses become less competitive or unprofitable?
  • How will soils and soil management be affected?

Because farming systems, practices and productivity are different in different parts of the state, answers to these questions will differ according to the land use and where it is placed in Victoria. A regional approach to analysis of these different situations is needed. This will assist in providing regionally relevant scenarios and advice. A division of Victoria into major ‘Primary Production Landscapes’ is proposed.

Rationale

The approach is similar to that applied in defining ‘Agro-ecological zones’ (AEZ), in which climate and soil properties are used to map and determine the suitability of land for different crops (FAO 1981). However, in a time of uncertainty regarding future climate, it is not possible to use climatic data to define fixed attributes of a zone. On the other hand, terrain and location (e.g. relative to the coast or high country) have a local influence on climate (e.g. continental rainfall gradients, orographic rainfall, and temperature gradients) and are relatively permanent features. Landscape differences (soil and terrain) in combination with general spatial trends in climate can therefore be used to delineate ‘agro-ecological landscapes’ (AEL), or areas with different potential for land use and different requirements for management (e.g. waterlogging may be a constraint that requires special consideration in some landscapes). MacEwan et al (2006) have used a similar physiographic approach to define zones to represent the high rainfall cropping zones in south east Australia. Primary Production Landscapes are AELs augmented with descriptions of primary production land use and management practices.

Method

Delineation and characterisation of AELs

Past approaches to mapping Victoria’s landscapes include land systems and the Victorian Geomorphology Framework (VGF). Regional location, physiographic divisions (incorporating terrain and geomorphology) and major soil types were used to delineate AELs. These AELs were characterised for dominant soil types and associated inherent management issues. Landform descriptions have been collated from those of the VGF. AELs were also described by major agricultural industries and practices that occur within them. Statewide maps for key climatic variables including temperature, rainfall and growing season rainfall were used to provide context for predicted changes in climate across the AELs. Mapped AELs and descriptions were reviewed by regional industry experts (grazing – meat and wool, cropping, dairy and forestry) and primary producers.

Characterisation of production systems within AELs

Regional experts including government research and extension staff, consultant agronomists and farmers were provided with a draft map of the PPLs and were interviewed to gather information on:

• The dominant land use practices specific to the PPLs.

• Pressures on the industry or practices within the last ten drier years.

• Competition to particular enterprises from alternative land uses.

• Prognosis for the industry under the predicted climate scenarios.

Figure 2. Primary Production Landscapes of Victoria

Results

Soil and landscape data, land use maps, the climatic record, and regional experience of agronomists and land managers have been used to define Victoria’s major ‘Primary Production Landscapes’ (PPL). A two tier system of PPLs has been delineated (Figure 2) and an example summary description for the Northern Plains PPL is given below.

Changing climate across the PPLs

Data taken from the Bureau of Meteorology and model outputs for the CSIRO A1F1 climate scenario have been used to represent medium term (1975-1995) recent (1996-2005), and predicted rainfall and temperature values across the PPLs. The annual average temperature scenarios are shown in Figure 3.

(a) 1975-1995

(b) 1996-2005

(c) A1F1 2050 prediction

Figure 3. Average annual temperature for Victoria taken from historic data (a) 1970-1995 (b) 1996-2005 and from model predictions (c) for 2050 (CSIRO A1F1 prediction). Map boundaries for Primary Production Landscapes shown in black.

An approximation to the growing season using a start date of May 1st has been represented by subtracting the cumulative daily evaporation from the cumulative daily rainfall. Four scenarios have been evaluated using data for: the long term average from 1889-2008, a mid term recent average for 1975-1995, the recent drier period from 1996-2008, and the average taken from the 10 driest years in the weather station record. Data have been analysed for each sub region. In general the most recent data fall on a line plotted midway between the long term average and the 10 driest years, although there are exceptions. The most recent data for Ouyen follow, almost exactly, the data for the 10 driest years experienced since the start of records. In contrast, data for Casterton (Southern Plains) show little difference for the long term average, mid term and recent periods. For illustration purposes data for the Northern Plains are shown in Figure 4.

Figure 4. Cumulative Rainfall minus Evaporation for two weather stations in the Northern Plains PPL.

Example summary description of land use and soil issues for the Northern Plains PPL

Each PPL has been described according to the agricultural industries and associated farming systems that operate within, major soil types (classified according to Isbell (2002) and Northcote (1979)) and inherent soil management issues (Table 2). Management issues (constraints) have been assessed for potential impact upon production capacity using a traffic light approach:

  • Red = significant management constraint limiting production capacity.
  • Amber = a management constraint that may limit production capacity.
  • Green = not considered a serious soil constraint to production.

Table 1. Farming systems, dominant soil types and associated inherent soil management issues for Northern Plains PPLs

Conclusions

This project has developed an approach that encapsulates information on landforms, soils, farming systems, management practices and future climate predictions. Understanding the agricultural capability for production as well as potential impacts on the displacement and redundancy of infrastructure for land uses remains a challenge for NRM managers, planners and policy makers. This spatial hierarchy of PPLs provides a regional platform from which to explore climate change and variability impacts upon agricultural industries and to target investment.

Acknowledgments

This research was supported by funding from the Our Rural Landscapes Extension (ORLe) Program through the Victorian Department of Primary Industries (DPI). The authors would like to thank regional experts from DPI, agricultural industry representatives and primary producers for their insightful contributions to this project.

References

Department of Sustainability and Environment (2004) Simplified pre-1750 native vegetation of Victoria

FAO (1981) Report on the agro-ecological zones project (1978-1981), Volume 1: methodology and results for Africa. World Soil Resources Report 48/1. Food and Agricultural Organisation (FAO) of the United Nations, Luxemburg, Austria, Rome, Italy.

Isbell RF (2002) The Australian Soil Classification. Revised Edition. CSIRO Publishing, Collingwoood, Victoria.

MacEwan RJ, Crawford DM, Newton PJ, Clune TS (2006) Subsoil Constraints to Cropping in the High Rainfall Zone of South East Australia – a scoping study. Department of Primary Industries. Final Report to GRDC for project DAV00056.

Northcote KR (1979) A Factual Key for the Recognition of Australian Soils. 4th edition. Rellim Technical Publications. Glenside, South Australia.

Victorian Geomorphology Framework (2008) http://www.dpi.vic.gov.au/dpi/vro/vrosite.nsf/pages/landform_geomorphology

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