Author: Mangadas Lumban Gaol

Abstract: This research was to determine the composition, diversity, and invasiveness of herbaceous plants in grassland communities of West Timor. Ten stations (Penfui, Alak, Bakunase, Tode, Mulafa, Oesapa, Tanah Merah, Tilong, Bukit Cinta, and Naketuka) were purposely selected, and at each station, 15 plots (1 m x 1 m) were randomly palace (∑150 plots). In each plot, all herbaceous species were recorded. The density, dominance, frequency, and Importance Value Index (IVI) of each species was calculated. Each species was further classified as invasive and noninvasive. Species diversity was calculated by the Shannon-Wienner Index and the similarity between stations was calculated by Sørensen coefficient (Ss). From 150 plots, 134 herbs species from 32 families were obtained. Of the species, the grass (Poaceae) was 26 (19.40%) species (IVI 25.24%) while non-grass was 108 (80.60%) species (IVI 74.76%). The grassland was dominated by non-grass. Based on IVI, grasslands were dominated by Euphorbia hirta L (13,93%), Eleusine indica (L.) Gaertn (12,46%), and Cyperus rotundus L (11,72%). The general pattern of grassland was that only a few species were in the abundant category and the dominant species were a rare category. About 80% of the species were in the category of low and very low. The grasslands were dominated by the Poaceae family with 26 (19.40%) species and IVI of 25.24%, and Asteraceae and Fabaceae with 20 species (14.93%) each with an IVI of 13.93% and 12.91%, while other families are only represented by <10 species. The average diversity index in all areas was 2.5779 (moderate). The similarity index (IS) between stations was relatively low (11.46%). Therefore, the diversity of herbaceous plants in the grasslands was relatively high. Of all species, E. hirta, E. indica, and Tridax procumbens L. were the most widely distributed, and the category had very high IVI. Therefore, the presence of these species in agricultural land needs attention. Of the 134 species, 90 (67.16%) species were potentially invasive (IVI 75.4%). Thus, the grassland was dominated by potentially invasive species with a contribution of around 70%. The high contribution of invasive species indicates that the area has faced threats from invasive weeds and severe degradation. It is important to develop a monitoring system, to understand the status of invasive species, take precautions to suppress their further expansion, and carry out restoration of ecosystems that have been damaged by the presence of invasive species. The species with very low IVI category also require high conservation priority in the management of the West Timor grassland community.

Keywords: grasslands, herbaceous species, Importance Value Index, diversity, species invasive