Introduction

Condition

Pressure

Response

Introduction

To implement a number of recommendations of the Meander Valley Council's Natural Resource Management Strategy, the Council, supported by Bushcare, commissioned a report into the feasibility of using multi-temporal LANDSAT TM satellite imagery to monitor broad landscape degradation trends, particularly vegetation condition changes and loss of biodiversity, across the municipality. This report, Landscape Change in the Meander Valley: A Case Study for Monitoring and Reporting of Land Use Modification, Vegetation Condition and Biodiversity Loss, brings together the work of CSIRO, Environment Australia, Bushcare, the Department of Primary Industries Water and Environment staff and Meander Valley Council.

The Council covers an area of approximately 3,320 km² in north central Tasmania and has a resident population of 17,375 (Australian Bureau of Statistics 2001). The area has a strong agricultural base with wool, beef and dairy being the main agricultural commodities. Cropping (in particular poppy growing) is emerging as an important source of income where conditions are suitable. Sawlog and pulpwood harvesting from native forests and plantations also generates significant income. There is an increasing trend towards vegetation conversion as landowners replace remnant native vegetation and established agricultural land with pine or eucalypt plantations to diversify their source of income (Inspiring Place 2000).

Using the Australian Land Use and Management Classification (Bureau of Rural Sciences 2002), land use analysis (Drenen 2003) reveals that approximately 45% of land within the Council area is used for conservation of the natural environment, 20% for production from relatively natural environments (grazing natural vegetation and/or production forestry from native forests), 29% for dryland agriculture and plantation production, 3.5% for irrigated agriculture and plantations, 1.5% for intensive use (urban development etc.) and 1% for water features.

Condition

The municipality contains relatively high biodiversity values due to a variety of topography, landscapes, climate, geology, and soil and vegetation types. Five major river systems originate within the Council's boundaries. Extensive areas of native vegetation support diverse plant communities with over half of the State's native plant species, 33% of which are endemic to Tasmania. The area also supports a rich variety of fauna, including a number of ancient relict invertebrate species in addition to other Tasmanian endemic species. Together, these variables have resulted in parts of the municipality being recognized for their state-wide, national and international significance through World Heritage, the National Estate Register, the Comprehensive Adequate Representative (CAR) reserve system, and threatened species identification.

The larger areas of the municipality containing the greatest biodiversity tend to be within crown land tenures, many of which are protected by individual or regional management plans implemented by the Parks and Wildlife Service or Forestry Tasmania (Inspiring Place 2000).

Pressure

Biodiversity loss is acknowledged widely both in Australia and globally as one of the most significant environmental threats (Commonwealth of Australia 1996). Ultimately the threats to biodiversity at a landscape scale can be distilled into two components; loss of habitat and by inference the threatened species they contain or may contain, and a deterioration in the condition of habitat which if left unchecked leads to the first component.

Loss of condition is in fact on a continuum with pristine ecosystems at one end and heavily degraded environments at the other. Native vegetation loss is often regarded as the best surrogate measure of this - at least for terrestrial ecosystems (Saunders et al. 1998).

Recent efforts in Tasmania to protect biodiversity have focused largely on the creation of a crown reserve system. Additionally, there has been in place a federally funded on ground works program to stabilise and enhance condition on private land, together with a voluntary financial incentive scheme to protect forest communities on private land within a private forest reserve program. The crown reserve system is not capable of protecting all elements of the State's terrestrial biodiversity. Indeed much contemporary public debate questions the adequacy of the crown reserve system to adequately protect all the elements of biodiversity that could be or need to be protected.

Given the often unsubstantiated accusations for and against broad scale land-clearing, and in the context of the large public investment in securing biodiversity outcomes in the Meander Valley, the need for accurate clearing data becomes acute. In the absence of a clear, well-documented and substantiated cases of significant habitat degradation, unproductive arguments about the adequacy of information occupies the body politic, rather than appropriate action. This is true at all levels of government.

In addition to these reasons Australia has Greenhouse abatement strategies in place, one aspect of which is the collection of accurate information in respect of the loss of woody vegetation in the landscape. There is recognition in Australian and international efforts to slow down the Greenhouse effect that a carbon trading system is a useful component (Commonwealth of Australia 1998). There is parallel recognition that this should not be environmentally perverse. In order to ensure robustness, these accreditation processes for carbon tradable plantations have focused on an early establishment date for the plantation and/or its establishment on long cleared agricultural land. This is so that the plantation represents a net-positive carbon-sequestration outcome and does not occur at the expense of biodiversity outcomes. The ability to convincingly demonstrate that a plantation has not been established at the expense of native forest therefore becomes critical (Cadman 2003).

Within the Meander Valley municipality (and elsewhere in the state) loss of biodiversity can be attributed to a number of processes;

• clearing and conversion of native vegetation, including the removal of all native vegetation for agriculture, urban development, and the planting of single species tree plantations
   


• tree decline (dieback) in agricultural areas caused by ageing and lack of replacement, grazing pressures, diseases and soil toxicity
   


• soil degradation such as loss of fertility, salination, reduction of soil organisms, and erosion
   


• urban and coastal development leading to fragmentation of bushland and draining of wetlands
   


• pollution and eutrophication of soils, water and air
   


• introduction of exotic and non-endemic species that can out-compete native species or invade vacant ecosystems niches, predate on native species and alter natural processes
   

Response

The need for institutional reform to improve biodiversity outcomes is an explicit goal sought in the NHT partnership agreement (Commonwealth of Australia 1998). This reform is expected to occur at all levels of government. Meander Valley Council, through its Natural Resource Management Committee, has been at the forefront of these processes.

As efforts focus in all jurisdictions to change Natural Resource Management Planning and funding to regional approaches, then accurate agreed baselines, monitoring processes and reporting mechanisms need to be in identified within Regional NRM implementation and investment plans. In this context the Landscape Change in the Meander Valley study is timely as it proposes a practicable, implementable solution for regional-state scale monitoring and reporting that can be further refined to deliver solutions to higher order accreditation requirements such as may well be necessary in carbon trading regimes.

Four objectives for the study were identified:

1. An assessment of the utility of a multi temporal woody change analysis undertaken by CSIRO (Perth) covering the municipality and subsequent use of this data to determine woody change trends in the municipality and changes by sub-catchment.
    
2. The determination of the feasibility of attributing woody change using a range of different vegetation data sets including a satellite vegetation classification, with the subsequent determination of biodiversity loss over time.
    
3. The policy and methodological reform that the results from the analytical work suggest.
    
4. An additional objective was to undertake a quick comparison between Tasmanian State of the Environment data sets and the data derived for the case study project.
    

The results of the study can be summarized as follows;

• It has been possible to accurately determine woody to non-woody change over a nine-year period and report against this by sub-catchment.
   
• By pursuing a two-fold approach using vegetation classification derived from digital satellite data and comparing these with other available vegetation data sets, it has been possible to establish indicative trends in vegetation loss by community, accurately determine and confirm areas subject to conversion to agriculture or plantation, and identify areas of native forest harvesting from 1995 - 2000.
   
• The results from 1995-2000 have been mapped and represented as areas of high biodiversity loss (conversion of native vegetation) and moderate biodiversity loss (harvesting).
   
• In the period 1995 - 2000, 2,993 ha of native woody vegetation was lost to plantations, agricultural development or urbanisation in Meander Valley.
   
• The indicative trends show that forest communities identified as a priority for protection continued to be cleared in the period 1995-2000, including those considered endangered.
   
• The data showed a strong link between woody - non-woody change and plantation establishment with clearing rates accelerating post 1998.
   
• It was not possible to determine areas of woody weeds or woody weeds in understoreys. The methodological approach did not allow for the determination of clearance of non-woody native vegetation.
   
• The need for monitoring and reporting reform in the emerging Natural Resource Management policy environment is demonstrated and analysis and administrative frameworks proposed.
   

The case study report contains a detailed set of conclusions drawn from the methodologies used and results obtained, and has made a set of recommendations for implementation. The most significant recommendations are:

• biannual reporting of 'biodiversity loss' should be adopted.
   
• State Government agencies should work towards monitoring and reporting reform.
   
• Regional Natural Resource Management processes should establish baselines and monitoring regimes for regional vegetation management outcomes based on a robust spatial approach (Cadman 2003).