Plant diversity in managed sal ( Shorea robusta Gaertn.) forests of Gorakhpur, India: species composition, regeneration and conservation

Abstract

The sal (Shorea robusta) forest vegetation of Sohagibarawa Wildlife Sanctuary, Gorakhpur, India was analysed to assess plant diversity, regeneration pattern and the status of species conservation. A total of 208 plant species representing 165 genera and 72 families were recorded. Species richness, mean density and basal area of individuals in the observed forest were compared with those of other sal-dominated forests of India. The sal forest was rich in Papilionaceae (23 species), which contributed maximally to the total number of individuals of <30 cm girth. After sal, density was maximal for a leguminous shrub, Moghania chappar. In addition to the usual recruitment by seed, a number of species also showed non-seed regeneration through storage roots, sprouts or ramet proliferation. The individuals regenerating as sprouts from underground stem or storage organs contributed significantly to the sum total of individuals/ha. As much as 45.5% of the total individuals were of ramet origin and shared 10.6% of the total species richness of the forest. In stands facing moderate to low disturbance, thickets of dense entangled mass of vegetation, predominantly composed of thorny lianas, were identified that usually contained less common and rare species like Rauwolfia serpentina, Desmodium latifolium, Crotalaria alata and Gloriosa superba in addition to the frequent ones. These thickets help to conserve the special habitat conditions and provide protection for natural regeneration of several infrequent and rare plant species and thus contribute towards the maintenance and in situ conservation of overall diversity of recurrently disturbed forest vegetation.