Avaliação de métodos etnobotânicos e ecológicos em estudos de diagnóstico rápido da biodiversidade

Abstract

The necessity to generate biological information in short time is eminent considering the fast loss of diversity around world. Facing the variety of methods for collection of data on the flora, which would be the recommended ones for the little time for execution without losing efficiency? The present work aims to evaluate the efficiency and time of execution of ecological methods, sample plot (SP) and quarter point method (QPM) and ethnobotanical (interview in the community, participative workshop and inventory-interview) in the fast sampling of the flora in an area of arborescent Caatinga, located in the Carão small farm, in the Altinho municipality, Pernambuco State, Brazil. Two areas were selected from a participative workshop: the first without indication of recent use (Area 1); the second, which was abandoned after a plantation 30 years ago (Area 2). In each area 20 sample plot of 10 x 20 m and 200 quadrant points were installed and wood plants with diameter of ≥ 3 cm in the level of the ground were sampled. Comparisons between areas and methods were made: a) Diversity, from t test; b) Richness was registered based on Cochran test and estimated from Jackknife test; c) phytosociological parameters, from the Medium Euclidean distance; and d) total sampling effort among the methods. As for the ethnobotanic methods, a participative workshop was carried out with 32 people. Photographs and exsiccates were presented to them as visual stimulus, in order to collect names and uses of 62 species of plants registered during the fitossociological inventory. The same plants were presented in situ for two local specialists, who indicated its names and uses. Data collected for the group of applied ethnobotany since 2006 were used, from half-structured interviews carried through with the adult population. From these data the Using Value (VU) was calculated. In order to compare the register of plants among the methods, the Cochran test was applied, in which each method was considered a sample and each specie was considered present or absent, for its recognition or citation in each method, beyond the grouping analysis using the Jaccard coefficient of similarity and form of linking UPGMA. The correlation between VU with Relative Density (DeR) and Value of Importance (VI) for the method of parcels and quadrant points in both studied areas was evaluated. The QPM presented minor sampling error in relation to the SP, however this one can underestimate the local diversity. Even if the method of parcels demands more time, it must be used in estimative of diversity and other phytosociological parameters. The method of quadrants is useful in fast inventories in the Caatinga for sampling of richness. The great population of Croton blanchetianus is indicative of disturbance. The involvement of people contributes to the election of sampling areas. More species in the inventory-interview had been recognized (44 species) and the participative workshop presented more errors in the identification (9 species). It was verified 100% of similarity between the participative workshop and the inventory-interview, and both had presented 100% of difference with the general interview with all community, and such differences are significant (Q = 13,37; gl = 2; p = 0,0013). One verified correlation between VU with DeR and VI for the quadrant point method in Area 2 (rs = - 0,53; p = 0,02 and rs = - 0,59; p = 0,0008 respectively). The involvement of parataxonomists is important in the fast diversity evaluation, but caution is necessary when using photographs and exsiccates as visual stimulus. The method of quadrant points is faster and can be useful to register local plants for posterior collection of ethnobotanic information.