The structure of the herbaceous forest layer around Wiidu Thiengoli drilling site has been studied for a fifteen-year-period to determine spatial structure floristic composition. The data was analysed, using multidimensional methods (Factorial analysis of correlation) and showed high variability in floristic composition and a ì memory effect î. This latter is more important when the reference year is exceptionally dry or wet. Comparison of floristic sampling among sites near the drilling (highly disturbed) with sites farthest away (undisturbed) showed that there are specific floristic composition changes correlated with zoo-anthropic disturbance.