Diversity of understory plants in undisturbed and disturbed tropical lowland forests of Little Andaman Island, India

Abstract

Species richness and density of understory plants were investigated in eight 1 ha plots, distributed one each in undisturbed and disturbed tropical evergreen, semievergreen, deciduous and littoral forests of Little Andaman island, India, which falls under one of the eight hottest hotspots of Biodiversity in the world viz. the Indo-Burma. One hundred 1 m -2 quadrats were established in each 1 ha plot, in which all the understory plants (that include herbs, undershrubs, shrubs and herbaceous climbers) were enumerated. The total density of understory plants was 6,812 individuals (851 ha -1 ) and species richness was 108 species, representing 104 genera and 50 families. Across the four forest types and eight study plots, the species richness ranged from 10 to 39 species ha -1 . All the disturbed sites harbored greater number of species than their undisturbed counterparts. Herbs dominated by species (63%) and density (4,259 individuals). The grass Eragrostis tenella (1,860 individuals; IVI 40), the invasive climber Mikania cordata (803; IVI 20) and the shrub Anaxagorea luzonensis (481; IVI 17.5) were the most abundant species. Poaceae, Asteraceae, Acanthaceae, Orchidaceae and Euphorbiaceae constituted the species-rich families represented by 6 species each. The species-area curves attained an asymptote at 0.8 ha level except in sites DD and DL, indicating 1 ha plot is not sufficient to capture all the understory species in disturbed forests. The alien weeds formed about one-fourth of the species richness (31 species; 28%) and density (1,926 individuals; 28.3%) in the study sites, indicating the extent of weed invasion and the attention required for effective conservation of the native biodiversity of the fragile island forest ecosystem.

Floristic Composition of Groundcover Vegetation after the 2010 Pyroclastic Fire on Mount Merapi

“…A modified importance value index (IVI) for each species was calculated by summing its relative density and relative frequency in each plot, following Rasingam and Parthasarathy (2009). A modified family importance value (FIV) for each family was estimated as the sum of relative diversity and relative density of the individuals in that family.…”

Structure and composition of the understory treelets in a non-dipterocarp forest of tropical Asia

“…Notably, Dipterocarpaceae is the dominant family in the three Asian sites, comprising about 14% of the 1-2 cm DBH trees in Asian forests and dominating the largest SAM class (Losos and Leigh, 2004;LaFrankie et al, 2006). Though available evidence shows that non-dipterocarp forests of Asia differ a lot from dipterocarp forests with respect to forest structure, species diversity and taxonomic composition of overstory trees (Cao and Zhang, 1997;Hamann et al, 1999;Kessler et al, 2005;Zheng et al, 2006), we still know little about the patterns of understory in the non-dipterocarp forests of tropical Asia except for some studies carried out in tropical evergreen forest of India (Rasingam and Parthasarathy, 2009). Consequently, our knowledge on the understory of tropical forests in Asia may be biased, more data from different areas are critically needed.…”

Medicinal plants in old-growth, degraded and re-growth forests of NW Pakistan

“…Similarly, D'Amato et al (2009) indicated higher abundance, richness and diversity of understory species in old-growth forests compared to second-growth forests in hemlock forests in western Massachusetts. In contrast, some studies indicated a lower abundance of ground flora under undisturbed, abundant overstory in comparison to disturbed and more open overstories (Kumar and Ram, 2005;Nath et al, 2005;Rasingam and Parthasarathy, 2008). However, in these studies, ground species were taken as a whole when comparing disturbed with undisturbed forests and there are also certain factors that can influence the comparison, such as individual species characteristics and grazing pressure (Albrecht and McCarthy, 2009;Martin et al, 2009).…”