Species richness, diversity, structure, and distribution patterns across dominating forest communities of low and mid-hills in the Central Himalaya

The forests of the central Himalayan region are characterized by the dominance of some populous and conspicuous tree species across altitudes that are crucial for ecosystem functions and services. An understanding of such forests with relation to species richness, diversity, structural pattern, and distribution is crucial in maintaining ecosystem stability. Considering this, the present study was undertaken on the four most common forest types dominated with Sal (Shorea robusta), Chir-pine (Pinus roxburghii), and Banj-oak (Quercus leucotrichophora), and mixed-oak (Q. lanuginosa and Q. floribunda) between 300 and 2250 m msl. Across the studied forest stands, we recorded a total of 110 plant species, belonging to 53 families. The most dominating life form was herbaceous (52%), followed by trees (27%), and shrubs (21%). Tree density was recorded maximum (884 ind. ha−1) at the mixed oak stand and minimum (652 ind. ha−1) recorded at the chir-pine forest; however, maximum (51.58 m2 ha−1) total basal area (TBA) was recorded in banj-oak forest and minimum (33.42 m2 ha−1) at mixed-oak forest stand. Tree density, seedling density, and TBA are significantly varied among the forest stands. The temperate oak forests comprised higher species richness and diversity at tree and shrub stratum. However, subtropical sal and chir-pine stand recorded higher regeneration. All stands exhibited high community dependence on forest resources that may increase the vulnerability of forest with respect to human interference, thus deserve immediate attention. Site-specific management and conservation measures have been suggested to provide opportunities for sustainable management of all forest stands.