Byron Flora and Fauna Study 1999 - Byron Shire Council

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BYRON FLORA AND FAUNA STUDY, 1999 • frequently occur in remnant, regrowth or planted rainforest in northern NSW • have a detrimental effect on indigenous rainforest vegetation • disrupt the ability of rainforest to regenerate and expand unaided • are difficult to control • are able to spread rapidly The common weeds of northern NSW rainforests are described and illustrated, and control methods described by The Big Scrub Rainforest Landcare Group (1998b). Buchanan (1989) is a useful reference for weeds of other communities. Environmental weeds such as Camphor Laurel, Bitou Bush, Lantana, Large-leaved Privet and Small-leaved Privet are well recognised in the Shire. Many others are known to occur, but may not be recognised as such by the general community. They include common garden plants such as the Asparagus Fern’s Protasparagus spp., Glory Lily Gloriosa superba, Mother-in-Law’s Tongue Sansevieria trifasciata, Cherry Guava, Coffee Coffea arabica, Japanese Honeysuckle Lonicera japonica, Cocos Palm Syagrus romanzoffiana, Broad-leaved Pepper Tree Schinus terebinthifolia and Umbrella Tree Schefflera actinophylla. Exotic creepers are particularly invasive and amongst a range of other weeds pose a significant threat to high quality vegetation communities in the Shire. Species of concern include; Madeira Vine Anredera cordifolia (Photo 34), Dutchmen’s Pipe Aristolochia elegans, Balloon Vine Cardiospermum grandiflorum, Cape Ivy Delairea odorata, Five-leaved Morning Glory Ipomoea cairica, Blue Morning Glory Ipomoea indica, Cats Claw vine Macfadyena unguis-cati, Corky Passionfruit Passiflora suberosa, Ground Asparagus Protasparagus aethiopicus (Photo 33), Climbing Asparagus Fern Protasparagus africanus, Asparagus Fern Protasparagus plumosus, Kudzu Pueraria lobata and Wandering Dew. This study has demonstrated the extent of occurrence of Camphor Laurel in the study area (Section 4.6.3). A large area of Large-leaved Privet at Mt Chincogan was also mapped. Many other species of environmental weeds were recorded at sites surveyed during the plot-based vegetation survey. However, most environmental weeds cannot be detected using API, and systematic ground-based surveys are required. Hence this study provides only limited information about the distribution and abundance of environmental weeds, and further work is recommended. For instance the area mapped for Large-leaved Privet does not reflect the true extent of its distribution in Byron Shire. Both Large-leaved Privet and Small-leaved Privet are considered to be much more widespread in Byron Shire, and commonly occupy the mid to lower strata and edges of remnant and regrowth forest. Fortunately, there are a number of serious environmental weeds that are notable for their absence, or presence only in small localized infestations in the Shire. Where areas are currently free of problematic weeds, there is an excellent opportunity to keep those areas free of weed problems by early detection and eradication of any infestation. In controlling environmental weeds, due consideration for their positive characteristics is required. Some weeds like Tobacco Bush may act as colonizers, providing suitable nurse conditions for the introduction of native species of later successional stages, but unless these areas are managed and/or suitable seed sources are close by, it is likely that other weed species will move in and permanently dominate the site. Weeds may stabilize soil and build soil fertility and biomass in degraded sites. However there is, without exception, always a native species that can fulfil the same role without the disadvantage of acting as an undesirable seed source. Environmental weeds can provide valuable fauna habitat. Camphor Laurel, and to a lesser extent Largeleaved and Small-leaved Privet, are important food sources for frugivorous birds. Lantana provides shelter for ground-dwelling fauna species. A general strategy of gradual removal and replacement with appropriate native species is suggested. 85
A GREENPRINT FOR A SUSTAINABLE FUTURE The management of Camphor Laurel in particular has been controversial in the Shire and the region. Its abundance, apparent site dominance, ability to invade disturbed native vegetation and the fact that it is presently in the early stages of an expansion phase suggest that control is necessary. The tree’s lifecycle is relatively long, and it is therefore difficult to predict the long term future of sites that are currently dominated by Camphor Laurel. The sites may eventually revert to rainforest, or Camphor Laurel may replace itself and permanently dominate the site. Variability in site characteristics and native seed sources as well as the inherent characteristics of Camphor Laurel may determine the outcome. Research is required to approach this question indirectly, since the processes are too long to rely on observation for the information needed to guide management. A great deal of useful work is currently being carried out by Landcare Groups, landholders as individuals, land management agencies and through labour market training programs. However, the threat posed to the Shire’s ecosystems from invasion of environmental weeds is severe. The following actions are required to prevent continuing degradation: 86 • Comprehensive surveys to identify the abundance and distribution of environmental weeds - required to ensure that scarce resources are allocated where they will have the greatest benefit. Surveys should be carried out on a local basis (LAMP areas, by Landcare Groups or on a catchment basis) and coordinated at Shire or regional level. • Development of species-specific management strategies with Camphor Laurel, Bitou Bush, Kudzu, the Asparagus Ferns, Madeira Vine, Cats Claw Vine, Wandering Dew, Large-leaved Privet and Small-leaved Privet as priorities. If regeneration of a native community is the desired outcome following removal of the target species, it is essential to take a whole system approach in developing management strategies. Removal of a target species frequently creates conditions conducive to the invasion of other weeds (R. Joseph unpublished reports). • Community education to prevent dumping of garden refuse and to avoid planting of environmental weeds. The list of undesirable species supplied with this study (Appendix 12), should be rated according to degree of threat and made available to the public. • Education of nurseries and landscapers. Nurseries should be invited to voluntarily participate in a certification scheme to not supply species with weed potential. • Advice to be available for landholders. • Untrained workers should seek advice before undertaking rehabilitation works. It may be appropriate to seek funding to employ trained teams of bush regenerators. 7.4 FIRE Fire is a regular and widespread source of disturbance in most Australian ecosystems (Fox and Fox 1986), though it rarely penetrates far into rainforests. Many communities and species are specifically adapted to withstand and recover from burning. Some plant species require fire at specific intervals to achieve reproduction or regeneration. Before the presence of humans, fires were caused by lightning strikes. Aboriginal people used fire as a tool to modify their living and hunting environment, though the extent to which this resulted in large-scale and long term vegetation change is a controversial subject. Although fire kills or damages some Australian plants, it promotes regeneration in other species, typically components of drier vegetation types. Fire can stimulate germination of hard-coated seeds such as acacias, while smoke stimulates germination of species including some grevilleas. Seed is held in capsules or cones in the canopy to be released following the heat of a fire in some species of eucalypt and banksia. Plants such as sedges resprout from underground rhizomes, some woody species have epicormic buds or a basal lignotuber from which new growth can arise. Fire promotes flowering in grass trees (Xanthorrhoea spp.). Generally speaking, rainforest plants have little fire tolerance. Fire impacts can vary according to the frequency, intensity and seasonality of the fire. An alteration to an existing fire regime will modify native vegetation in a manner predictable from the life
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Byron Flora and Fauna Study 1999 - Byron Shire Council

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