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MANAGEMENT OF SIGNIFICANT SITES—WHAT IS THE ROLE OF VEGETATION?

Management of geological sites is often confused with other conservation ideas. This section is to assist those managers of geological sites.
 
INTRODUCTION
Although there has been a growing recognition of the value of natural heritage in the last few decades, the importance of conserving geological features is still frequently overlooked. Yet Victoria has a rich diversity of sites that are geologically significant, ranging from massive landmarks of great beauty to inconspicuous outcrops of a few square metres.
Often perceived as robust features, these outcrops and landforms are in fact vulnerable to a number of threats. One concern that is becoming increasingly apparent is that of revegetation and associated land rehabilitation works on both public and private land. Rock faces in cuttings and quarries that have long provided valuable exposures for excursions, scientific reference and research are increasingly being obscured by plantings or destroyed altogether in accompanying landscaping. Tree planting around lookouts and viewpoints is interfering with previously expansive views of surrounding landforms and landscapes. Landforms that have been identified as geologically significant are being concealed beneath a mantle of trees and shrubs. In some parks the very features that were cited as reasons for creating the reserve are now scarcely visible.
The benefits of revegetation are wide ranging, and with careful planning it should be possible to enhance the biological, aesthetic and safety values at geologically significant sites without compromising the geological values.
A set of principles, standards and guidelines which may help both government and non-government land managers address revegetation and associated rehabilitation issues at sites of geological significance is discussed below.
WHAT ARE SITES OF GEOLOGICAL SIGNIFICANCE?
Geological heritage sites are places where the rocks, landforms and landscapes have special value in letting us understand the composition of the earth’s crust, the processes, past and current, that shaped it, and the evolving flora and fauna that occupies it.
Key rock exposures and landforms have been identified throughout Victoria and range in size from thousands of square kilometres to less than a hundred square metres. Sites may be important because of their fossil, rock or mineral content or their landscape. They may reveal unusual or outstanding sedimentary or igneous structures or are type sections that define particular geological units. In some, cases the relationships between different rock units is well displayed. Some have associated cultural interest—perhaps mining relics or a well-known geological identity.
Many sites of geological significance result from human activities, not natural processes. Road and railway cuttings and quarries often provide the best exposures, particularly in areas where natural outcrop is scarce. Landforms may be the result of natural processes or reflect differing degrees of human interference with the landscape. Some sites are lookouts or viewpoint from which aspects of regional geology and active geomorphological processes can be best appreciated.
THE VALUE OF GEOLOGICAL SITES
Geological heritage sites are important for many reasons. Professional geologists in both the private and public sector use the sites for reference and research. For geology teachers, accessible field areas are an invaluable educational resource. Amateur geologists, field naturalists and members of the public are also interested in visiting and understanding sites. Tourist trails with interpretive signage and geological guides are in increasing demand at geologically interesting areas. The more spectacular geological settings such as the Port Campbell National Park and the Grampians have long been popular tourist destinations for their aesthetic, recreational and historic experiences. Certain landforms have particular spiritual or cultural significance to Aborigines.
THE REGISTER OF GEOLOGICAL FEATURES OF SIGNIFICANCE
The Geological Heritage Subcommittee of the Geological Society of Australia is compiling an inventory of sites of geological and geomorphological significance within Victoria, in conjunction with the Geological Survey of Victoria. The project aims to record sites of interest on a database if they are an outstanding or unusual example of a feature or if they provide a useful representative example of a widespread phenomenon. Once identified and documented, the sites are assessed by a panel of geologists as being of international, national, regional or local significance. A statement of significance records why the place is important. The register, which currently contains over one thousand sites is continually updated with new sites added or existing details modified to reflect changed circumstances or new information.
The Environment Conservation Council (and its predecessor, the Land Conservation Council) as well as various government departments, local councils and organisations have also commissioned inventories of sites of geological significance within specific geographic boundaries.
These valuable data resources are all too often overlooked when planning and land management strategies and being developed. As a consequence irreplaceable exposures and landforms are being lost. Current quarrying and engineering practices do not generally favour the creation of new sites. Pits and quarries are more often progressively backfilled during the course of operations or are soon reused as waste disposal sites. Road cuttings are typically cut back to a low slope and revegetated or reinforced. Railway lines are being decommissioned and cuttings allowed to become overgrown. It is important therefore to conserve those geological sites that have particular value.
THREATS TO GEOLOGICAL SITES FROM LAND REHABILITATION
Whilst rehabilitation work is just one of the activities that can destroy or diminish the value of geological features, its impact is increasingly being noticed and needs to be addressed. It is not just small sites that are vulnerable, large landforms too can be substantially affected. Sometimes the impact is immediate and obvious but other times the disturbance is incremental over a long period.
Rehabilitation work can impact on geological sites in a number of ways.
  • The plants themselves may obscure the feature itself or views of the feature, either as a result of inappropriate height, bushiness or density of planting.
  • Engineering works may be implemented to re-contour the land thereby destroying existing exposures.
  • Soil may be added to a site as a substrate for planting thereby burying outcrops.
  • Stricter management measures may be adopted on revegetated sites, which prohibit the removal of rock specimens from sites that have traditionally been accessible for collecting.
  • Human traffic may be confined to delineated pathways or restricted by fencing so that close inspection of outcrop is no longer possible.
  • Uncontrolled weed growth may obscure features of interest.
  • Engineering structures such as sound walls and concrete retaining walls can obscure exposures.
  • Engineering works or large-scale plantings may irreversibly affect drainage patterns thereby altering existing geomorphic features. This is of particular concern in limestone (karst) areas and sites where active geomorphic processes contribute to the site’s significance.
PRINCIPLES
The following principles are put forward for management of sites of geological significance.
  • Sites that have been identified as geologically significant should be managed in such a way that those features that contribute to its geological value are retained or enhanced and not obscured, damaged or destroyed. Within the boundaries of a large site, the components that have special value may not be distributed uniformly so that practices that are acceptable or desirable in one part may not be in another part.
  • Where sites have a range of heritage values then conservation should be based on respecting all the differing values of the place without unwarranted emphasis on any one aspect at the expense of others.
  • Conservation planning and management should make use of all disciplines and experience that can contribute to the study and safeguarding of the place.
  • Revegetation and associated land rehabilitation operations that adversely impact on geological values should only be undertaken for essential purposes where no other alternative strategy is available.
REVEGETATION GUIDELINES FOR LAND MANAGERS OF SITES OF GEOLOGICAL SIGNIFICANCE
These guidelines are intended to assist both government and non-government planners and land managers to identify sites of geological significance and to protect those locations from inappropriate revegetation strategies.
  • Ascertain whether or not the site has geological significance. This information may already be available in the GSA’s database (see below for contact details), in regional listings or excursion guides. If not it may be necessary to undertake further geological research to identify any significant geological components of the site.
  • Develop a management plan in which all special geological values are described and ensure that these geological components and viewing lines are clearly identified on a site analysis plan. Specific objectives and rehabilitation proposals must be consistent with the overall rehabilitation plan.
  • The type and density of revegetation should not obscure significant outcrops, exposures, landforms or views. Species selection should have regard to height of the mature plant, canopy spread and density of growth.
  • Conservation works should be sympathetic to both biological and geological values. Where a conflict arises between these values, experts in all relevant fields should examine the site, make recommendations and together work towards an acceptable solution.
  • Educational and tourism values of a site can be enhanced in certain situations by the provision of roadside stops, walking tracks and interpretive material.
  • Some sites of geological significance include unstable or hazardous rock faces. If these need to be stabilised or made safe, alternatives to vegetation cover that would maintain visibility should be investigated eg. meshwork.
  • Ongoing monitoring should be undertaken routinely to ensure that geological values are not being interfered with as plants grow and reproduce. In areas where the geological feature has been obscured, appropriate trimming or judicious removal of vegetation should be carried out.

last updated: May 22, 2009