Woody plant restoration and natural regeneration in wet meadow at Coomonderry Swamp on the south coast of New South Wales

Abstract

This study investigated planting techniques and natural regeneration of indigenous woody species within degraded wet meadow wetland at Coomonderry Swamp. Planting tubestock directly into existing vegetation was practical and cost-effective. Clearing of plots allowed infiltration of weeds, early growth of tubestock was inhibited, acid sulfate soils were exposed, and open inundated plots were choked by algae. After four years, Melaleuca ericifolia and Melaleuca linariifolia showed good survivorship at upper and lower elevations. Eucalyptus robusta and Casuarina glauca were more successful at upper elevations, and Leptospermum juniperinum did not succeed at either elevation. These results corresponded to patterns of regeneration and to distributions within undisturbed stands. Despite the evidence of natural regeneration, direct seeding was not successful at the experimental site. Given that poor dispersal was indicated at Coomonderry Swamp, it is unlikely that isolated wetlands in the region could rely solely on seed dispersal for woody revegetation. Even where regeneration can occur naturally, some planting or culling might be required if the desired outcome is a species mix comparable to that observed on undisturbed margins.

Rehabilitation of Swamp Paperbark (Melaleuca ericifolia) wetlands in south-eastern Australia: effects of hydrology, microtopography, plant age and planting technique on the success of community-based revegetation trials

“…Dowd Morass, in common with many other coastal wetlands in south-eastern Australia, has Table 4 Percentage survival, plant height and water depth for Experiment 2 over a 5-month period for 6-month-old seedlings of M. ericifolia planted in two water depth treatments at Site 2 using either a mattock or Hamilton planter been degraded by near-permanent flooding, low soil pH and highly saline soil and surface water (de Jong 1997;Turner and Lewis 1997;de Jong 2000;Davis et al 2001). The very poor survival of tubestock seedlings observed in our study is undoubtedly related to this highly stressful combination of adverse environmental factors, and demonstrates the difficulties associated with rehabilitating degraded brackish-water wetlands.…”

“…Seedlings and young plants of many Melaleuca species, including M. ericifolia, are known to be highly tolerant of waterlogging (Ladiges et al 1981;de Jong 2000;Salter et al 2006), and are capable of active root growth in waterlogged soils through the production of aerenchyma in the roots (Ladiges et al 1981). It is noteworthy, however, that the survival of 6-month-old seedlings of M. ericifolia in the exposed (i.e., dry to semi-damp) plots was 15-25% higher than for seedlings planted in the waterlogged or fully flooded plots 1 month after planting.…”

“…Three water depths were chosen because communitybased replanting activities may have little control over the depth of water in a wetland targeted for revegetation (de Jong 2000). Within each plot, 4-month-old plants (n = 20) and 6-month-old plants (n = 25) were planted 2 m apart using a mattock to create a hole in the sediment into which the tubestock was inserted.…”

“…The rehabilitation strategy is based largely on revegetation efforts, usually commissioned by management agencies and then devolved to contractors or community groups, who in turn frequently transfer revegetation methods to wetlands that have been developed in terrestrial or riparian environments. With few exceptions, the effectiveness of wetland revegetation efforts have not been experimentally tested and there is little accountability of the success of the projects that have been undertaken (de Jong 2000;Close and Davidson 2002).…”

“…Since the distribution and abundance of M. ericifolia has decreased markedly with the clearing and draining of wetlands along the entire coast of Australia (Bowkett and Kirkpatrick 2003), a priority of natural-resource management agencies and non-government organisations throughout Australia is the rehabilitation of the wetlands that contain, or did contain, M. ericifolia and other Melaleuca species (de Jong 1997;Turner and Lewis 1997;de Jong 2000).…”