Adaptation and efficiency of an index for bioty integrity analysis in tropical rain forest

Abstract

Among the different ways of measuring the biotic integrity of a particular forest area, the Rapid Ecological Assessment (REA) stands out. Based on REA, an index was developed to evaluate the quality of the vegetation called the Biotic Integrity Index (BII). The measurement and accuracy of this index show how integral is the forest ecosystem at moment of analysis. The basis for efficiency in the application of BII is the correct choice of biotic integrity indicators or the variables to be measured. The present study was based from an index previously proposed for a Seasonal Semideciduous Forest (SSF), and aimed to adapt the BII for use in an area of Dense Ombrophilous Forest (DOF) in the State of São Paulo as well as to test its efficiency in diagnosing the integrity of fragments of a Tropical Rain Forest (TRF) inserted in a rural matrix. From the eleven indicators present in the original method, some were kept as original or adapted, some removed and some new ones were created. The adapted BII was applied in a TRF area of 70 hectares. To do so, 20 plots of 10x10m were used, within the sampling area. The results showed a variation of IIB from 28 to 47, and 2 plots recorded low integrity, 11 medium integrity and 7 good integrity. The area showed regular integrity as a whole, which was expected due to its size, agricultural surrounding and history of disturbances. The BII showed to be adapted and efficient to analyze the biotic integrity of the DOF, as it was able to show the difference of integrity between different patches of TRF. The least efficient indicators were: “litter cover” and “exotic woody species”, and the most efficient were: “Euterpe edulis”, “epiphytes”, “gaps” and “vines”.