Species diversity and community structure in sal (Shorea robusta) forests of two different rainfall regimes in West Bengal, India

Abstract

Knowledge on the structure and composition of the plant communities has enormous significance in conservation and management of forests. The present study aimed to assess the community attributes, viz., structure, composition and diversity in the moist and dry sal (Shorea robusta) forests in the West Bengal province of India and compare them with the other sal forests of India. The phytosociological data from these forests were quantitatively analysed to work out the species richness, diversity, evenness, dominance, importance value, stand density and the basal area. The analysis showed that plant richness and diversity in moist sal forests of northern West Bengal are higher than the dry sal forests of south-west Bengal; a total of 134 tree (cbh C30 cm), 113 shrub and 230 herb species were recorded in the moist sal forest compared to 35 tree, 41 shrub and 96 herb species in dry sal forest. Papilionaceae was observed to be the dominant family. Dry sal forests had higher tree dominance (0.81) and stand density (1,006 stems ha -1 ) but lower basal area (19.62 m 2 ha -1 ) while moist sal forest had lower tree dominance (0.18) and stand density (438 stems ha -1 ) but higher basal area (56.52 m 2 ha -1 ). Tree species richness and stem density across girth classes in both the types decreased from the smallest to largest trees, while the occurrence rate of species increased with increase in girth class. A t-test showed significant differences in species richness, basal area and the stand density at 95% confidence level (p = \0.05) in the two forest types. The CCA indicated very low overall match (canonical correlation value = 0.40) between the two sets of variables from moist and dry sal types. The differences in these forests could be attributed to the distinct variations in climatic conditions-mainly the rainfall, disturbance regimes and the management practices.

Patterns of species dominance, diversity and dispersion in ‘Khasi hill sal’ forest ecosystem in northeast India

“…A study from foothills of Darjeeling Himalaya showed that the diversity of tree species is much higher in sal forests than previously hypothesized (Shankar 2001). Subsequent studies from the same region confirmed the trend (Kushwaha and Nandy 2012).…”

“…However, a case of high tree diversity in a sal forest was reported from Mahananda wildlife sanctuary in foothills of eastern Himalaya in the beginning of this century (Shankar 2001). Further investigation spanning larger geographical area of eastern Himalayan terai (including Darjeeling, Jalpaiguri and Coochbehar) endorsed that sal forests of this region harbour high levels of woody species diversity (Kushwaha and Nandy 2012). Floristic inventories in sal forests vary dramatically in plot size, sampled area, and measurement threshold of minimum stem diameter, imposing a restriction in comparison of species richness (Table 5).…”

Assessment of Tree Alpha Diversity in Chapramari Wildlife Sanctuary, Eastern Himalaya

“…Previous studies have reported 215 species of trees from seven forest types of Darjeeling foothills , 134 species of trees in the dry and moist sal forests of northern West Bengal (Kushwaha & Nandy 2012), 87 species of trees in Mahananda Wildlife Sanctuary (Shankar 2001), 74 species of trees in tropical parts of Darjeeling hills (Moktan & Das 2014). In addition to studies solely focusing on estimation of tree species richness many Figure 6.…”

“…Forests of Central and Eastern Himalaya are also rich in plant species diversity and endemism (Singh & Singh 1987;Shankar 2001;Behera et al 2002;Das & Ghosh 2011;Kandel et al 2016), at the same time these forests are under heavy anthropogenic disturbances posing a threat on the existence of many rare species in the forest communities (Pandit et al 2007;Bhuyan et al 2003;Kushwaha & Nandy 2012). Eastern Himalayan forests are highly diverse as compared to northwest Himalaya with approximately fivefold higher number of species (Purohit & Dhar 1997).…”

The charms and challenges of climate change biodiversity in a warming world

“…Kale and Roy (2012), however, observed a good correlation between NPP and plant diversity in another Indian tropical dry deciduous forest site. In yet another study, Kushwaha and Nandy (2012) found a significant decrease in plant species diversity from moist to dry forests differing in rainfall, disturbance, and management practices.…”