Evaluating different methods used in ethnobotanical and ecological studies to record plant biodiversity.

Background: This study compares the efficiency of identifying the plants in an area of semi-arid Northeast Brazil by methods that a) access the local knowledge used in ethnobotanical studies using semi-structured interviews conducted within the entire community, an inventory interview conducted with two participants using the previously collected vegetation inventory, and a participatory workshop presenting exsiccates and photographs to 32 people and b) inventory the vegetation (phytosociology) in locations with different histories of disturbance using rectangular plots and quadrant points.

Methods: The proportion of species identified using each method was then compared with Cochran's Q test. We calculated the use value (UV) of each species using semi-structured interviews; this quantitative index was correlated against values of the vegetation's structural importance obtained from the sample plot method and point-centered quarter method applied in two areas with different historical usage.