The trait-based approach to weed management utilises functional traits to categorise weeds into management groups based on their behaviour (Kooyman et al. 2007). Initially, 53 rainforest weeds were identified and then categorised into five broad groups that represent the influence of dispersal (including fruit size, seed size and dispersal mode), shade tolerance, persistence (capacity to resprout or persist on site by seed-based regeneration) and the component of the forest structure they are most likely to affect (ground, mid canopy or canopy). Further refinement of the five groups has identified three management groups and several subgroups provided below. Since the original analysis of Kooyman et al. (2007), further weed taxa have been identified and placed in the category that best reflects their functional traits.
The final weed groupings provide an overall indication of a weed’s ability to exploit undisturbed or disturbed rainforest or edges of rainforest, its method of dispersal and the stratum of the forest it potentially threatens most. Those weeds able to establish in full shade (i.e. exploit intact rainforest) and affect the canopy are possibly the group of greatest threat in the Planning Area, while weeds in shade intolerant groups are most likely to be a threat to riparian edges and fragmented remnants.
A weed’s dispersal mechanism also has the potential to influence management options. For example, the ability to contain an infestation is potentially greater for weeds that are not actively dispersed by vectors such as wind or frugivory. An exception to this, however, is in riparian areas where water can provide an effective dispersal mechanism. In such areas, treatment of weeds immediately adjacent to the water edge is essential before working in areas further back. It is also important to work in the upper catchment first to prevent ongoing reinfestation from upstream areas.
Identification of rainforest weeds of the Planning Area is an ongoing process. For each new weed taxon, expert knowledge can be used to add the taxon to the relevant weed management group. Taxa are still being identified as being either present in the rainforest of the Planning Area or potential invaders (Big Scrub Rainforest Landcare Group 2000; H. Bower pers. comm.; B. McDonald pers. comm.). These are yet to be placed in appropriate groups and include:
Cestrum elegans at Mt Glorious and Tamborine Springs
African Boxthorn Licium ferocissimum in western Main Range
Pepper Tree Schinus areira in western Main Range
Guinea Grass Megathyrsus maximus var. maximus and Green Panic M. m. var. pubiglumus in drier rainforest areas
Cherry Guava Psidium cattleianum at Broken Head and Wilsons Creek in NSW
Big Scrub Rainforest Landcare Group 2000, Common Weeds of Northern NSW Rainforests. A Practical Manual on their Identification and Control, 2nd Edition, Big Scrub Rainforest Landcare Group, Bangalow.
Kooyman, K., Rossetto, M. and Jamieson, I. 2007, Border Ranges Biodiversity Management Plan: Defining ‘weed species’ groups based on life-history traits to inform and determine threat groups, Unpub. report prepared for DECC, National Herbarium of NSW and Far North Coast Weeds, Lismore.
1 Loss of genetic integrity is also referred to as ‘genetic stochasticity’ (Lindenmayer & Fisher 2006; Ouborg et al. 2006) or ‘genetic deterioration’ (Hobbs & Yates 2003).
Border Ranges Rainforest Biodiversity Management Plan