Australasian Plant Conservation
Originally published in Australasian Plant Conservation 19(2) September - November 2010, p 3-4
GUEST EDITORIAL: Conservation management of linear vegetation remnants in Australia
Dr Peter Spooner
Charles Sturt University, Albury, NSW. Email: email@example.com
Figure 1. Parish map of Lowes (County of Hume), located north of Corowa, NSW showing a typical arrangement of land parcels and roads, as a result of land-use decisions in the late 1800s. Open (solid dashed lines), closed (diagonal hatch lines) and unused ‘paper’ road reserves are shown, which are the result of later council decisions to manage the road network. Source: NSW Land and Property Management Authority 2010.
Roadside environments are a ubiquitous component of the Australian landscape. Within this vast network of corridors, remnants of native vegetation often provide the only remaining evidence of extensive forests, woodlands and grassland ecosystems which once graced the countryside. In conjunction with other transport corridors, roadsides often constitute a significant proportion of native vegetation remaining in agricultural or urbanized areas, and provide important refuge for populations of native plants, many of which are threatened or endangered. Australia is indeed fortunate to possess these linear remnants, but how did they get there?
The narrow area of land which contains the road and surrounding environments is a road reserve—an area of public land set aside to provide transportation routes, many of which were first surveyed in the late 19th century. As our landscapes were subdivided for settlement (mostly after Land Acts implemented in 1861), road reserves were also surveyed so all title holders could gain access to water. Most road reserves were originally surveyed at one chain (20.12 m) width, which was suitable for a horse and carriage of the times, but barely wide enough for modern transportation needs. Major trunk routes, rail reserves and stock routes were also surveyed at widths of 1.5–5 chains (30–60.3 m), depending on transport use at the time (Figure 1). The (indirect) legacy of these past land-use decisions is an extensive network of vegetated corridors traversing much of the developed areas of our country.
By the early 1900s, much of the ‘road network’ was nothing more than an ad-hoc collection of narrow vegetation corridors, where travellers navigated their way through the trees and mud, along rough bush tracks. Local councils had the enormous task of making this network trafficable, where individual road reserves that were required for transport use were declared as ‘open’ roads. Development of road networks continued throughout much of the early 1900s, which also resulted in decisions not to use many previously surveyed road reserves (known locally as ‘paper roads’, in reference to their existence as ‘roads’ on parish maps). Later, councils would close a number of unused road reserves, and these bush corridors provide enormous conservation opportunities (Figure 1). Unfortunately, a number of state governments have not realized these values, and sold off many over the years.
Stock routes are also an integral component of road networks in many states. Indeed, most of the general public would not know if they are travelling down a normal road or stock route. The clue is in the width of the corridor.
Many stock routes were surveyed up to a half or one mile wide, however most are three chains (60.3 m) wide. These are our oldest roads, and were developed to link grazing lands to markets and other forage areas. Their development created our largest network of vegetated corridors which, by the late 1800s, was in the order of millions of hectares. Today, the network is much reduced, although many components still remain which possess significant conservation values.
Since the late 1980s, there has been increasing attention toward the conservation management of stock routes and other roadside environments. Rather than use a grader to remove roadside vegetation for safety concerns, more enlightened councils are now endeavouring to better manage these precious biodiversity assets. In the 1990s, bodies such as the NSW Roadside Environment Committee were formed to encourage the better management of the roadside environments, by providing training and assistance to identify the natural and cultural heritage values of roadsides. For example, most councils have used a rapid bio-assessment methodology of some kind to assess the conservation values of each road segment (ranked as High, Medium or Low). These rankings are then used to determine appropriate management actions for each road category, as described in local roadside management plans.
Efforts to maintain roadsides vary enormously from one council area to the next, which largely depends on available funding and other issues (e.g. see articles in Australasian Plant Conservation 18(3)). In many areas, rural councils cannot afford a dedicated environment officer, and so compliance to any roadside plan is often lacking. On this issue, roadside vegetation plans need to be promulgated in local by-laws for any compliance to take place, else they can languish as a dusty survey document in the engineer’s office. Another issue is that training of council workers in the recognition of roadside conservation values is often lacking or non-existent, and local contract workers are often over-looked in the process. Ongoing training is necessary for workers to know exactly where the ‘good bits’ are, so as to avoid damage by heavy machinery. To this end, simple marking of roadsides (using colour-coded markers on existing road reflector posts) has been implemented in some council areas to warn road managers of sensitive vegetation areas.
It is critical for state-based natural resources agencies to provide further training and resources towards the conservation management of roadsides. Yes, councils are responsible for their management; but given that conservation outcomes derived from roadsides can greatly contribute to catchment- or state-based conservation targets, these assets cannot be ignored. Also, in terms of future climate change scenarios, we are fortunate to already have a ‘green network’ in place to assist native species to disperse across the landscape. In this context, it is vital that roadside vegetation networks are maintained and even improved with further restoration inputs. Vegetation conditions can improve or deteriorate, depending on prevailing disturbances (e.g. stock grazing, or soil disturbances from grading), edge effects, impacts from the surrounding farmlands, or internal roadway stressors. Therefore regular monitoring of conditions is highly desirable to refine management inputs.
Road reserves and stock routes also have many cultural heritage values to consider. For example, a number of our roads literally follow the tracks of our first explorers and settlers. Likewise, stock routes were developed by drovers, squatters, settlers and indigenous peoples, leaving an exciting historic narrative to recount. Indeed, a number of stock routes are thought to follow previous indigenous traditional pathways, so could be thousands of years old. As such, each road has a story to tell, which could be a useful approach in interpreting and educating the general public of broader roadside vegetation values.
It’s important to note that the cultural heritage values of roads and stock routes are not just confined to physical structures or other historic evidence, but can be recognised for possessing uncommon, rare or endangered aspects of our natural history (e.g. rare or endangered plants or ecosystems). In turn, these species, habitats, and remnant ecosystems provide important aesthetic values, which are unique to this country.
Other more novel linear remnants demand equal attention. Railway reserves provide unique habitats for many key flora where, in many locations, past rail management activities (e.g. burning) have ensured the persistence of important grassland species. As a result, many local groups have taken the opportunity to develop closed rail reserves to better manage their natural and recreational values. Likewise, corridors created by utilities and powerlines can provide refuge for some plant species.
Local naturalist and Landcare groups, councils and larger state-base agencies often do a wonderful job in conserving the vegetation in road reserves, stock routes and rail reserves. However key threats such as grazing, invasive species and pollution from adjacent areas require constant vigilance. As human constructions, the key to success in ensuring the persistence of the roadside vegetation is in addressing the ongoing human threats, and better recognition of their conservation and cultural heritage values.