Abstract:
This thesis concerns Jatropha curcas, a proposed biofuel crop in New Zealand. The main aim of this study was to determine whether J. curcas has the potential to establish and become invasive in New Zealand by; 1) predicting the potential distribution of J. curcas under current and future climate change conditions in New Zealand and to test the modelling procedure used for this purpose, and 2) examine the viability and persistence of J. curcas seeds in various habitat types burial depths and burial durations in New Zealand. The first of these goals was approached using the computerised species distribution modelling package MaxEnt. The second was achieved by field burial tests of seeds, subsequently followed by a viability test using Triphenyl Tetrazolium Chloride. Modelling results suggest that J. curcas will be able to colonise much of the North Island and parts of the South Island under future climate conditions. Preference for warm temperatures was found to be a determining variable in predicting J. curcas’s distribution range, as the species in frost intolerant. The potential ranges under current climate conditions were limited to a handful of areas in the North Island and to Westport in the South Island. An assessment of MaxEnt indicates that it is robust to low levels of input data, supporting its usefulness as a tool for predicting the spread of invasive species. The viability test of J. curcas seeds indicate are high rate of viability (89%) across all test factors and consequently increases its potential as an invasive weed in New Zealand. Seed persistence was also found to be high in J. curcas with the seeds being able to persist for a minimum of 9 months and still remain viable. This consequentially, further increases the invasive potential of J. curcas and indicates that caution must be taken with any proposed cultivation of this species in New Zealand.
