C.2.3 WeedsC.2.3 Weeds

C.2.3 Weeds

No Weeds of National Significance are known to affect any populations of Asplenium listeri.

Numerous species of weeds have invaded forest margins along roads and tracks and around mining fields, and sparse vegetation communities, such as those on the terraces, are also vulnerable to such invasion.

The very hardy native ferns Nephrolepis multiflora (scurfy sword fern) and Nephrolepis biserrata (broad sword fern) can spread aggressively to form dense and tangled colonies which confound access, and compete strongly with other plants (Swarbrick 1997). N. multiflora is particularly noted as an invader of mining fields (CofA 2002) where it is often dominant in areas of poor thin soil and limestone pinnacles, while also forming dense thickets more than 2 metres tall in damper, more shaded gullies towards the margins of old mines (DuPuy 1993c). However, there is no evidence that either species is competing with Asplenium listeri in its exposed cliff-top habitat (Reddell pers. comm.).

With the possible (and uncertain) exception of former habitat that may have been affected by weed invasion following mining, the specialised habitat now occupied by Asplenium listeri makes it unlikely that weed invasion has contributed to the restricted distribution of the species through competition, and there is no reference to weed species in records of known localities. The most recent survey notes that the species is not subject to tangible threats from invasive weeds (Holmes & Holmes 2002).