Methodology proposed for photogrammetric monitoring of the exotic species Hovenia dulcis Thunb. in the Green Belt area surrounding the city of Santa Cruz do Sul, RS, Brazil.

The spread of the exotic species Hovenia dulcis known as Japanese raisin tree, coming from Asia, detected in a protected area of 465.0 ha surrounding the city of Santa Cruz do Sul, RS, Brazil, named "Green Belt." In this context, this research aimed at developing an aerial monitoring system able to identify and quantify the extension in the Green Belt area that this species invaded, as well as describing the impacts caused on the local forest community. We collected data from an ultralight Flyer GT aircraft equipped with a vertical camera. The images were taking in June and July 2015, when H. dulcis trees have shed their leaves, displaying a gray color, and September and October 2015, when the leaves are young and with a light green color. Based on the methodology proposed trough aerial monitoring by photogrammetry, the results indicated that the total invaded area by H. dulcis in the Green Belt of Santa Cruz do Sul County, RS, was 131.8 ha, corresponding to 20.9% of the total area. To validate this method, a quantitative comparison between the result from a terrestrial fieldwork carried out and the proposed method showed no significant differences in the estimated area occupied by H. dulcis. We concluded that these results validate the proposed aerial assessment method.