Variation in ecophysiology and carbon economy of invasive and native woody vines of riparian zones in south-eastern Queensland
Osunkoya OO; Bayliss D; Panetta FD; Vivian-Smith G
Exotic and invasive woody vines are major environmental weeds of riparian areas rainforest communities and remnant natural vegetation in coastal eastern Australia where they smother standing vegetation including large trees and cause canopy collapse. We investigated through glasshouse resource manipulative experiments the ecophysiological traits that might facilitate faster growth better resource acquisition and/or utilization and thus dominance of four exotic and invasive vines of South East Queensland Australia compared with their native counterparts. Relative growth rate was not significantly different between the two groups but water use efficiency (WUE) was higher in the native species while the converse was observed for light use efficiency (quantum efficiency AQE) and maximum photosynthesis on a mass basis (inline image). The invasive species as a group also exhibited higher respiration load higher light compensation point and higher specific leaf area. There were stronger correlations of leaf traits and greater structural (but not physiological) plasticity in invasive species than in their native counterparts. The scaling coefficients of resource use efficiencies (WUE AQE and respiration efficiency) as well as those of fitness (biomass accumulated) versus many of the performance traits examined did not differ between the two species-origin groups but there were indications of significant shifts in elevation (intercept values) and shifts along common slopes in many of these relationships – signalling differences in carbon economy (revenue returned per unit energy invested) and/or resource usage. Using ordination and based on 14 ecophysiological attributes a fair level of separation between the two groups was achieved (51.5% explanatory power) with AQE light compensation point respiration load WUE specific leaf area and leaf area ratio in decreasing order being the main drivers. This study suggests similarity in trait plasticity especially for physiological traits but there appear to be fundamental differences in carbon economy and resource conservation between native and invasive vine species.