By Edgar Freimanis
Key words: urban bushland restoration, site remediation, direct return topsoil, plant salvage, transplanting.
Introduction: As a bush regeneration contractor often working adjacent to development sites in the Sydney Region it occurred to me that plants and topsoil earmarked for destruction at a development site could be salvaged and translocated to improve results in nearby or similar restoration areas. Monocots lend themselves to this process due to their comparatively shallow, fibrous and stoloniferous root systems that have adapted to regrowing after disturbance.
Works undertaken and results. Over the years our bush regeneration contract team has translocated monocots at a range of project sites where natural regeneration potential is very low. Typically this technique accompanies our more conventional planting of nursery grown tree and shrub tubestock in these areas. The soils in these recipient areas are usually similar to those of the donor sites from where they were sourced. If weed management is needed, the recipient sites are typically weeded before transplanting takes place. We use hand tools such as shovels to dig-up variable sized sections of mostly native grasses and some other native monocotyledonous plant sods from areas that have been designated for development and other similar authorised clearing.
The sods are placed into plastic trays, moved and directly transplanted into parts of adjoining bushland conservation areas that have been designated for reconstruction planting. The transplants can be placed within recipient sites at similar densities to grassy ground layer tubestock plantings, (e.g. at densities of between 1-4-plants per m2, or more) or laid out like turf in continuous sections,
Plant establishment aids such as water retention crystals and fertilisers are also applied to each transplant at planting to assist with plant survival and establishment. The transplants are watered-in initially and on subsequent occasions, depending on prevailing soil moisture conditions, project resources and project timing.
Ongoing follow-up bush regeneration weeding is typically undertaken in the recipient sites, as required. (Fig 1). Monitoring has been confined to ‘before and after’ photo documentation, as shown in the following examples.
1. Tuckwell Road, Castle Hill Shale Sandstone Transition Forest and Sydney Turpentine Ironbark Forest Regeneration and Reconstruction of low residence sections. The recipient site was a rehabilitated old bitumen driveway within an estimated 0.40-hecatre bushland conservation and restoration area Native grasses and other monocots were transplanted from a bushland area that was being cleared for associated road widening works at a density of four plants/m2. (Figs 2 and 3).
2. Kellyville (Cumberland Plain Woodland site). The recipient site consisted of an edge of a bushland conservation area, that was subject to earthworks associated with a retirement village development. The recipient site’s soils were ripped to alleviate compaction and topsoiled with local clay-based topsoil. Native grass sods were transplanted from donor areas that were located within the approved development footprint area adjoining the bushland conservation area. The sods were cut into 200-300mm sections and placed in close proximity to on-another, not too dissimilar to a jig-saw puzzle or hand cut turf, to make a continuous grassy layer, with minimal gaps between transplanted sods. The transplanted sods were lightly filled and top-dressed with local topsoil to fill and level out any gaps between the sods, and then trimmed to surrounding ground levels and watered-in well. (Figs 4 and 5)
3.Spinifex transplanting on coastal sand dunes. In this project the rhizomous native grass sprinfex was transplanted into dunes from nearby areas at Corrimal Beach in the Wollongong local government area, as a part of works associated with Council’s 2013 Dune Management Implementation Plan. The spinifex transplanting works were undertaken in conjunction with weed control and tubestock reconstruction planting works.(Figs 6 and 7)
Benefits and characteristics of direct transplanting include:
- Reduction of lengthy plant propagation and seed collection phases;
- Avoidance of seed maturity restrictions and clashes with project construction phases;
- Guaranteed achievement of local provenance material;
- Ability to obtain species that are difficult to propagate or collect seed from;
- Potential inclusion of other plant species from donor to recipient sites (translocated as seed in the soil of transplanted sods);
- Achievement of similar densities to tubestock planting or turf-laying;
- Ease of implementation (transplanting monocots is a technique that has been long-practiced by bush regenerators, gardeners and horticulturists);
- Ability to conduct the treatments on a small scale using hand tools, or large scale using heavy machinery.
Barriers and challenges to direct transplanting include:
- Timing/gaining consent difficulties relating to compatibility of works between donor and recipient sites;
- Convincing consent authorities of the efficacy of this method;
- Technical issues: proximity of donor and recipient sites;
- Cost, (including maintenance and watering) which can be higher than other methods;
- Difficulty in transplanting some monocots;
- Potential for soil pathogen spread.
Acknowledgements: This summary was originally presented to the November 2014 Symposium ‘Rebuilding Ecosystems’ held at the Teachers’ Federation Conference Centre, Sydney by the Australian Association of Bush Regenerators (AABR)
Contact: Edgar Freimanis, Ecohort, ( PO Box 6540 Rouse Hill NSW Australia 2156 Tel: +61 418 162-970 Email: ed @ecohort.com)
Acknowledgement. This is summarised from a talk first presented to the symposium ‘Rebuilding Ecosystems: What are the Principles?’ Teachers’ Federation Conference Centre, November 13th, 2014, Australian Association of Bush Regenerators (AABR).