Indigo bush (Amorpha fruticosa L.) is an invasive shrub native from North America with great ecologic plasticity being found in different ecological conditions. This species is very aggressive replacing fast the native vegetation from different herbaceous vegetation communities. This species has incidence in western Romania, being spread along all the waterways (Mureş River, Danube River, Crişul Alb, Crişul Negru, Timiş, Bega, Bârzava) and their affluents, along the transport ways, but it started to be found in grasslands too. The data analyzed in this work were registered during 2005-2009 period from four grazed grasslands from Timis County (Voiteg, Moraviţa, Albina and Sacoşu Turcesc). There were performed vegetation surveys and the collected data were used for the calculation of different parameters of the grassland vegetation as are: floristic composition parameters and Shannon-Wiener index (H’) using natural logarithms. The mapping of the aerial projection of indigo bush on 100 m -2 (10 m -1 x 10 m -1 ) was done by dividing the studied surface into 100 sub-plots (1m x 1m). For each sub-plot we have evaluated the area covered with indigo bush plants (m -2 ). The data obtained in this way helped us to analyse the spatial distribution, and to calculate the coverage index for the studied species, which is the ratio between the total area covered by the indigo bush (sum of the areas covered in 100 sub-plots) and the total area of the plot (100 m -2 ). For the statistical analysis there was used the linear regression and correlation coefficient (r). The purpose of this research is to asses the influence of indigo bush on grasslands and its invasive potential on grassland vegetation from western Romania. There was determined the coverage index evolution and the dynamics of biodiversity. The results obtained show that indigo bush has increased invasive potential in grasslands with negative effects on the native vegetation.

Amorpha fruticosa L.; shrub; invasive; grassland; vegetation; biodiversity

Presentation: oral