Using Remote Sensing and a Cellular Automata-Markov Chains-GEOMOD model for the Quantification of the Future Spread of an Invasive Plant: A Case Study of Psidium guajava in Isabela Island, Galapagos

Abstract

Plant invasive species are one of the most important threats to the ecological stability of the Galapagos Islands and Psidium guajava is one of the most aggressive invasive plants: it currently occupies large areas in the middle and upper zones of some of the islands. This study measures the future spread of Psidium guajava in the south-east area of Isabela Island, Galapagos. Satellite image processing was used to calculate the area of occupation in the years 1980, 2001 and 2009. Then, a Cellular Automata-Markov chains-GEOMOD (CA_Markov_GEOMOD) model was made in order to represent a possible area of future occupancy of Psidium guajava. Results show a continuous invasion of this species in the entire study area and the model of future spread predicts a greater extension of occupation areas in 2030: a spreading rate of 108, 64 Ha / year between 2009 and 2030 was calculated. These results provide a better understanding of the spreading situation of this invasive species, which would support decision making processes to control the invasion.