Impact of ground cover vegetation types on the diversity and similarity of spider assemblage at two adjacent sites

Spider (Arachnida) is one of the classes of arthropods known to give strong responses to differences in land cover vegetation. This study intended to investigate whether the difference of vegetation types that are located adjacently occupied by the same genera of spiders. Two adjacent areas in Liwa Botanical Garden that covered by two different types vegetation were assigned as the sampling sites. The spiders sampling was carried out over a 100 meter long transect line (5 lines each) by applying active searching and pitfall trapping techniques. There were 21 genera from 9 spider families that were collected from two sampling sites. In the land vegetated with wood, there were 12 genera with 129 specimens. In the herbaceous land, there were 13 spider genera with 120 specimens. The Simpson's index of diversity were 0.7739 and 0.8868, meanwhile the Shannon's index were 1.8575and 2.2831, respectively obtained at herbaceous and woody land. The difference of diversity between two compared sites by Hutcheson t-test was highly significant (α < 0.01). This presumption is also supported by the coefficient of dissimilarity calculated using Sorensen’s index formula (Ss = 75.7575). Thus it can be concluded that the different types of land cover vegetation have a significant impact on the diversity of the dwelling spiders even though the two fields are located adjacent to each other.