ESTIMATING AND APPLYING BIOLOGICAL PARAMETERS TO ENHANCE MANAGEMENT OF RAUVOLFIA VOMITORIA AN INVASIVE TREE IN NORTH KOHALA, HAWAIʻI

Abstract

Introduced tree species can cause environmental harm through invasive traits like fast growth rates, long-term seed longevity, and long-distance seed dispersal. I estimated these rates for Rauvolfia vomitoria, a tree native to tropical Africa, which was introduced to Hawaii Island in the 1950’s. I then compared these rates to other local trees species, both native and invasive, in order to understand R. vomitoria’s relative invasive risk. It appears to be slow growing at ~1.4mm DBH growth annually, but its seeds can survive over 3 years and can be dispersed up to 1km. Managers have concluded R. vomitoria warrants control, and have decided to contain the invasion. Based on my estimates for growth and dispersal, I calculated the cost for a number of containment scenarios, which ranged from $36,000-$88,000 annually. Given that average annual funding for R. vomitoria control is ~$35,000, managers may need to request more funding or change management-tactics.