3.4. Habitats and Species Interaction
Observations of earthworm species abundance in the Sylhet region indicated that there were definite differences according to soil type both in total species numbers and in the relative numbers of species present (Table 2). The clay loamy appeared to carry higher earthworm species in total populations than the sandy loamy appeared to carry lower earthworm species (Table 1). Within and between the respective soil-type populations, species numbers were variable, but the actual numbers present on a soil type do not necessarily indicate the relative importance of each species. In all cases E. fetida was the dominant species, being more numerous on the clay loam than elsewhere. The abundance of A. aspergillum, A. caliginosa and A. longa were also observed in clay loamy. Species did not differ very much from L. castaneus and L. terrestris of the population on these two later soils and these two species were similar within populations, though much lower on the clay than on the other soils, and the total Lumbricus population number was highest on the loam and lowest on the clay (Table 2). There was a fair similarity between the two populations on the two open-textured soils, in both numbers and index values. Simpson’s diversity index value was found lowest in SUST campus and highest in Malnichara localities while almost similar value was recorded in Dhamalipara, Lakkatura and Kazitula habitats (Table 2).