Key Words: bush regeneration, selective herbicides, transplanting, cemetery management
Since 2006, Lismore City Council’s Lismore Memorial Gardens (LMG) has been restoring and managing a 1.5ha patch of regrowth Forest Red Gum (Eucalyptus tereticornis) grassy open forest in Goonellabah, north coast NSW – primarily for use as a bushland cemetery. The site was part of a registered corridor for Koalas (Phascolarctos cinereus) and was in a highly weedy condition prior to the commencement of the project. The understorey was dominated by Lantana (Lantana camara), constricting Koala movement, and most eucalypts had at least one multi-stemmed Camphor Laurel (Cinnamomum camphora) encircling it.
Bush regeneration works. In 2006 the lantana was mechanically cleared and Camphor Laurels were stem-injected with glyphosate herbicide. After woody weed removal, the ground stratum rapidly responded with a germination flush of herbaceous weeds, mainly Blue Billygoat Weed (Ageratum houstonianum), Farmers Friends (Bidens pilosa) and Broad-leaved Paspalum (Paspalum mandiocanum) although some native herbaceous species were also regenerating, particularly Basket Grass (Oplismenus aemulus), Weeping Grass (Microlaena stipoides) and Kidney Weed (Dichondra repens).
Subsequent detailed spot spraying with herbicides was undertaken; in the first few years on a monthly basis by volunteers, and more recently by a horticulture-trained LMG staff member after some workplace tuition in bush regeneration methods.
1. Resilient areas. Herbaceous weed was systematically sprayed with broad-leaf selective herbicides (Dicamba/MCPA plus surfactant) or glyphosate. Three larger patches consolidated with native species fairly rapidly, while other areas in poorer condition colonised with fewer species or took longer to convert to native dominance. There are now 69 species on site that are characteristic of this ecosystem (including 8 tree species, 15 grasses, 5 sedges, 8 twiners/climbers, 5 ferns and 1 moss). About 20 of these species have been added to the list since the start of the project and all existing species have vastly increased in cover and density. The intermittent watercourse area regenerated over time with wetland herbaceous species largely including Persicaria spp. and Cyperus exaltatus.
2. Highly weedy edge. Standard bush regeneration approaches over at least 2 years in an edge site proved intractable due to high weed contamination and low native richness. A trial was conducted in 2009to see if scalping and revegetation (using transplanting and direct seeding ) could reduce the amount of weed control required and improve native vegetation establishment. This involved removal by a grader of 10 cm of the weedy topsoil, with the remaining subsoil broken up with a backhoe and hand raked. Sods containing multiples of 10 species were taken from the healthier parts of the cemetery and transplanted to the raked site in mid- to late-September 2009, resulting in a total of 145 plants in each of three zones (one transplanted only, one transplanted plus direct seeded with 10 species and one neither transplanted nor seeded). Seven weeks later, when germination from the sods had occurred, it was observed that 17 species (i.e. seven more) had been transplanted (Table 1.) Very few individual transplants died.
Subsequent monitoring found that all the two scalped and revegetated zones, while requiring monthly weed control initially, had consolidated to a very low weed state by 9 months. There was little visible difference between them except that the seeded one contained two more species not present in the unseeded site. Within 18 months, both zones had very high cover levels of native vegetation, particularly native grasses, and weed control demand was substantially lower than adjacent edge sites treated with conventional spot spray methods alone. The non-transplanted or seeded zone remained with low species diversity and was more exposed to weed cover. It has since become an access track and requires higher weed control inputs than the adajacent revegetated areas.
Lessons learned. The bush regeneration treatments have converted a weed-dominated site to a recognisable Forest Red Gum grassy open forest with a diverse understorey. Cemetery operations are ongoing with the condition of the bushland showing an improvement with each year. Evidence of wildlife use of the habitat is increasing. This is due to ongoing management support, continuing volunteer inputs and the deployment of staff with some training in weed and bushland management. Although a range of highly problematic weeds (including Asian Copperburr, Acalypha australis, Prairie Grass, Bromus uniloides, and Hairy Commelina, (Commelina bengahlensis ) were initially not adequately addressed and are now requiring additional treatment; the site is a viable demonstration site for not only restoration techniques but also the district’s grassy understorey species, once so widespread but now rarely conserved .