Undergrowth phytodiversity index in exotic and indigenous tree plots in Hoteya forest range of Sakhipur upazila under Tangail forest division, Bangladesh

This study was undertaken to know the species diversity of the monoculture plantations of exotic species Acacia auriculiformis and Eucalyptus camadulensis compared to indigenous species Shorea robusta and Mangifera indica. There are 12 sample plots (size 36x36 m) were selected from the study area following the purposive random sampling. A total of 720 quadrats (12 plots x 10 quadrats x 6 seasons) were placed in the sample plots to collect the undergrowth vegetation data over two years of 2010-11 following summer, monsoon and winter season. The average value of Shannon-Wiener diversity index was 2.65±0.16 and 3.28±0.13 that of Simpson’s diversity index was 0.87±0.02 and 0.93±0.01 and that of Margalef’s diversity index was 7.34±0.77 and 10.43±0.52 collectively in all exotic and indigenous plots, respectively. This scenario depicts that the extent of species diversity was higher in indigenous tree species plots than in exotic tree plots and the flora of the study area was highly diversified. The Shorea plots were richer in species diversity out of the four species categories of sampling plots. The index values of three diversity indices were significantly different for the exotic and indigenous tree plots, excluding Eucalyptus and Mangifera species plots, which mean the undergrowth species diversity of Eucalyptus and Mangifera species plots, were not significantly different. Adequate awareness building programs need to conduct among the local community and Bangladesh Forest Department to understand environmental degradation, the importance of conservation management of indigenous ‘Sal’ forest and significance of plant diversity in the village forest for future generations.