Remote Sensing Survey of Melaleuca

Remote sensing was used to attempt to define the areal extent of the introduced tree Y1elaleuca quinquenervia in selected portions of south Florida. The area occupied by Y1elaleuca has increased markedly in recent years, in part because of populationinduced site modifications including hydroperiod changes resulting from artificial dminage, cutting of the native vegetation, and burning. LANDSAT imagery and computer analysis of the imagery by the General Electric Company's IMAGE-lOO machine were used to attempt to determine the extent of Vlelaleuca over much ofLee County and portions of Collier County in southeastern Florida. It was possible to identify some areas occupied by vlelaleuca, but not with adequate precision for purposes of detailed mapping. Efforts using the GE IMAGE-l 00 Pattern Recognition System were largely unsuccessful in identifying a unique signature for Vlelaleuca because the tree is found on a wide va riety of sites, it occurs in various degrees of mixture with other species, and in widely varying densities and size classes. Signatures which identified all of the known la'rge, mature stands dominated by Y1elaleuca also identified portions of other ecosystems which do not contain Y1elaleuca, particula'rly cypress and mangrove. Signatures narrow enough to exclude cypmss and mangrove failed to identify all of the large, nearly pure Y1elaleuca stands. Some preliminary testing of the technique lcas done with other south Florida ecosystems in the hopes ofbeing able to identify those ecosystem types which might be potentially susceptible to Y1elaleuca invasion. Ecosystems which are stntcturally simple such as barren areas, improved pastures, and some mangroves were readily identified, whereas those with a more complex structure such as pine forests, cypress swamps, and mixed pine-cypress-hardwood stands proved difficult to identify. Technology Satellite (ERTS, now LANDSAT) imagery to determine the areal extent of the exotic tree, Melaleuca quinquenervia ture in South Florida."1 There was concern that Melaleuca dominated a significant palt of the south Florida environment and that it