Land management and the Encroaching City Boundaries

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Becoming a park ranger, the dream job for so many Fenner graduates. Getting paid to spend the day in the field, relaxing amongst nature. But how does the idealised vision differ from fact, especially when within the urban interface? This is what I aimed to discover when I spent the day working with rangers Simon and Pat at Canberra Nature Park.

Canberra Nature Park is split into several offices across the ACT, firstly by urban and regional centres, then into district areas. The Mitchell office, where I worked, deals with all CNP land within the north of Canberra. The large majority of the rangers’ role is to monitor ongoing projects, and can also be ceremoniously unglamorous. Yearly, each ranger will deal with upwards of 500 road kill, management of feral animals through shooting and fumigation, including the annual culling of kangaroos, and spraying of invasive plant species.

The first job I was involved with was to check out Duntroon Dairy, a heritage listed building circa 1836, thought to be the oldest surviving building in Canberra (Fig 1). Nestled at the foothill of Mount Pleasant, along the Molonglo River, it was entrusted to CNP due to its historical value. From there we did a visual inspection of Mount Pleasant, which has significant issues with invasive species. This is a persistent problem due to the fact that portions of the land are owned by the Department of Defence, who have different management objectives to CNP, and thus makes interdepartmental affairs more difficult to deal with.

Figure 1: Top: Duntroon Dairy, Bottom: Map of Heritage site (Conservation Management Plan)

Mount Ainslie and Mount Majura, on the other hand, are well managed for invasive weed species and have limited associated problems in contrast to Mount Pleasant. This is partially due to the collective work done by volunteer community groups. Previously, cleared paddocks on Mount Majura were infested with Paterson’s curse, Hedge Mustard and Flatweed, as well as other invasive species (Fig. 2). However, ‘Friends of Mount Majura’ have worked to control them, and consequently native species have repopulated the area, restoring natural resilience to the system (Fig. 3).

Figure 2: Top: Paddock on Mount Majura prior to weed control, October 2007, consisting mainly of Paterson’s Curse

The same paddock on Mount Majura in 2012, after weed control (Friends of Mount Majura)

Figure 3: Paddock on Mount Majura – by removing competitive Paterson’s Curse native ground cover species, like Common Everlastings, Chrysocephalum apiculatum, regrew (Friend of Mount Majura).

Despite ongoing work to restore landscapes within CNP, there is evidence that urbanisation is having a severe impact. On a small-scale I observed this through the intrusion of residential yards onto reserve land, which included the planting of non-native species and encouragement of invasive species, like Chilean needle grass, to grow (Fig. 4).

Figure 4: Residential backyard intruding onto reserve land, encouraging Chilean needle grass to spread

 

 

 

 

 

 

 

 

 

 

 

Development intrusion was also viewed on Bruce Ridge, where the tourist park had contracted to place a physical barrier, preventing runoff from flooding their site. This involved removal of the understorey and significant disturbance to the site to allow heavy machinery in. CNP rangers are responsible for monitoring work, the extent to which the landscape has been altered and to evaluate how it is recovering over time. Currently, the site is highly disturbed in comparison to the surrounding landscape, with little to no ground cover, and it remains unknown whether the tourist park is contractually obliged to cover the cost of restoration (fig 5).

Figure 5: undisturbed sites on Bruce Ridge, O’Connor

Sites where drainage lines and a physical barrier have been erected to prevent runoff and erosion

Sites where vegetation had been removed to create barrier

On a large-scale, the threat of urban expansion is apparent within the grasslands and offset sites around Canberra. As new developments grow around the bush capital, rangers have to manage new areas of land designated as offset sites. A site adjacent to Mount Ainslie reserve has been given to CNP to counterbalance a nearby development, but offers several obstacles in the process to restoration. While invasive species are either controlled or sprayed for on Mount Ainslie, the offset site is chockfull of Serrated tussock, Chilean needle grass, Paterson’s curse and has an estimated population of 40,000 kangaroos, all of which will somehow have to be controlled and managed within a defined budget.

An effective management plan for weed control could include burning during early spring before the plants go to seed, however this can be challenging as it may still be too green. Furthermore, kangaroo culling within the ACT is a controversial issue, causing social and political tension, with many groups in open opposition, while rangers agreeing that it is the best, and sometimes only, management option.

Figure: 6 Visual representation of the drivers, pressures and effects of pressures viewed in CNP

The natural temperate grasslands of Australia once covered an estimated 250,000 hectares. However, it makes for prime agricultural land, and therefore it has become fragmented since European settlement, invaded by species like Serrated tussock, African Lovegrass, St. Johns Wart and Phalaris. Today only 1% of these lands remains in the ACT. Crace Grassland is home to rare and endemic species, like the Grassland Earless Dragon, the Stripped Legless Lizard and the Button Wrinklewort (fig. 7). Concern for these threatened species is driven by the fact that they occur within different patches of the grassland, but all face the risk disappearing from this site with the encroachment of St Johns Wort. The Button Wrinklewort, in particular, only occurs in a very small patch of loamy clay soils (fig. 8). The Grassland Earless Dragon and Stripped Legless Lizard have slightly different ecosystem requirements, and thus controlling St Johns Wort without harming their population is challenging for the rangers. Furthermore, Phalaris, a introduced grass, is prolific within this grassland, however kangaroos prefer to graze on native forbs. This causes increased grazing pressure on native species already under intense competition from weeds, and thus over time will deplete the biodiversity of the grasslands. One management solution is to lease the land out to cattle farmers, which controls the Phalaris, and by carrying out rotational grazing limits the total grazing pressure on the paddocks. Moreover, cattle decrease the fire risk by reducing fuel load.

Figure 7: Stripped Legless Lizard

Grassland Earless Dragon (Environment, ACT)

Figure 8: Grace Grassland, Mitchell, showing the area in which Button Wrinklewort grows. The loamy, clay soils only cover approximately 50 meters (Google maps)

Encroachment of the city edge and urban sprawl poses a large threat to the natural capital of Canberra. While the day-to-day work of an urban ranger may encompass cleaning up road kill, dealing with public complaints and giving ‘move on’ notices to swooping magpies, as human interaction with the environment inevitably increases, their work in protecting biodiversity will become increasingly vital.

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About Biodiversity Conservation Blog

I am an Associate Professor at The Australian National University and convene a (very awesome) course called Biodiversity Conservation. Myself and students in the course contribute to this blog.
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