Liane distribution within native forest remnants in two regions of the South Island, New Zealand

To determine the susceptibility of different forest types to lianes, and to investigate which ecological factors are limiting for lianes, a field survey covering 28 naturally forested sites in Golden Bay (Northwest Nelson) and on Banks Peninsula (Canterbury) was carried out. Results from Detrended Canonical Correspondence Analysis of liane species abundance data in relation to tree and shrub species abundance data and abiotic site variables, showed that the liane community composition was highly correlated with the composition of the tree and shrub community. Forest remnants with introduced lianes in the canopy were characterised by high soil pH, low altitude and high mean temperatures. Native lianes were more widespread geographically and showed a wider ecological tolerance range than introduced lianes. Native liane species were found in both early successional and mature forest, whereas introduced lianes occurred more often with early- successional vegetation. Forest canopy height was also an important factor affecting liane distribution and abundance. Both climbing mechanism and liane stem longevity seemed to affect the height of canopy accessible to lianes. The three twining lianes with longer-lived woody stems (Muehlenbeckia australis, Parsonsia spp. and Ripogonum scandens) reached higher host canopies than a twiner with herbaceous stems (Calystegia tuguriorum), a tendril climber (Passiflora mollisima), and a hook climber (Rubus cissoides). The susceptibility of individual tree and shrub species to canopy invasion by lianes was affected both by the light environment of the potential host, and the architectural properties (height and support availability) of the host.