What lies beneath? The pattern and abundance of the subterranean tuber bank of the invasive liana cat's claw creeper, Macfadyena unguis-cati (Bignoniaceae).

Abstract

Cat’s claw creeper, Macfadyena unguis-cati (L.) Gentry (Bignoniaceae) is a major environmental weed of riparian areas, rainforest communities and remnant natural vegetation in coastal Queensland and New South Wales, Australia. In densely infested areas, it smothers standing vegetation, including large trees, and causes canopy collapse. Quantitative data on the ecology of this invasive vine are generally lacking. The present study examines the underground tuber traits of M. unguis-cati and explores their links with aboveground parameters at five infested sites spanning both riparian and inland vegetation. Tubers were abundant in terms of density (~1000 per m2), although small in size and low in level of interconnectivity. M. unguis-cati also exhibits multiple stems per plant. Of all traits screened, the link between stand (stem density) and tuber density was the most significant and yielded a promising bivariate relationship for the purposes of estimation, prediction and management of what lies beneath the soil surface of a given M. unguis-cati infestation site. The study also suggests that new recruitment is primarily from seeds, not from vegetative propagation as previously thought. The results highlight the need for future biological-control efforts to focus on introducing specialist seed- and pod-feeding insects to reduce seed-output.

Cat's claw creeper vine, Macfadyena unguis-cati (Bignoniaceae), invasion impacts: comparative leaf nutrient content and effects on soil physicochemical properties

“…The increased nutrient concentrations mediated by M. unguiscati may be a straightforward consequence of increased fluxes of C and N in its nutrient-rich litter return and/or due to its higher net primary productivity (Dassonville et al 2008;Osunkoya et al 2010b). Indeed, we know that M. unguis-cati forms masses of subterranean tuberous roots and soil surfacerunning inter-twining stems with accompanying N-rich leaves which, on senescence, tend to create deep litter layers (at times up to 20 cm thick) (see Osunkoya et al 2009 (Ehrenfeld 2003). Increases in pH may reflect the preferential uptake of ammonium rather than nitrate as N source (as reflected in a significant negative correlation between the soil pH and ammonium; r = -0.72, n = 24, P = 0.001 in invaded soils only) or increased base-cation concentrations in the litter of M. unguiscati (Weidenhamer and Callaway 2010).…”

“…These subterranean tubers are usually golf-ball size (~25 mm  7 mm) and are massive in numbers (up tõ 1000 per m 3 ), promoting M. unguis-cati persistence and aiding its vegetative propagation (Osunkoya et al 2009). Some of its leaflets are modified to form pronged, claw-like tendrils with deciduous horny hooks, which enable the plant to climb natural and man-made structures.…”

“…In areas without standing vegetation or other structures (e.g. fences), the vines grow along the forest floor and form dense mats that preclude the recruitment and growth of native vegetation (Osunkoya et al 2009;Dhileepan 2012). The three remaining study species (see below) are the most abundant co-occurring vines with M. unguis-cati in both riparian and non-riparian habitats; however, their relative abundances differ across sites (O. O.…”

“…Macfadyana unguis-cati, a perennial woody climbing vine, native to tropical South America (Downey and Turnbull, 2007), has become a major environmental weed in Australia, especially in coastal Queensland (Qld) and New South Wales (NSW) where it poses a significant threat to biodiversity in exposed riparian areas, rainforest communities and remnant natural vegetation (Osunkoya et al 2009;Dhileepan 2012). It is also a declared weed of great significance in southern Africa (King and Madire, 2011).…”

Comparison of growth traits between abundant and uncommon forms of a non-native vine, Dolichandra unguis-cati (Bignoniaceae) in Australia

“…While LP occurs in isolated localities of south-east Queensland (Qld), SP occurs extensively in Qld and New South Wales, often in dense infestations (Dhileepan 2012;Downey and Turnbull 2007). These two forms appear to prefer similar habitats, although there is general lack of research on the ecology of this species (Osunkoya et al 2009). The LP and SP forms have been shown to carry an average of 120 ± 10 and 60 ± 23 seeds per pod at maturity, respectively (Shortus and Dhileepan 2011).…”