Abstract

The existence of a species in a forest community largely depends on its ability to regenerate under varied environmental conditions.  In the present study, effect of biotic disturbance was assessed and analysed on diversity and regeneration of pre-dominant tree species of oak forests. For this, two adjacent sites were selected in mixed oak forest zone (2100 m asl), namely, undisturbed open area (inside zoo) and moderately disturbed open area (out side zoo). Phytosociological analysis of tree and shrub layer vegetation was done and density, diversity index, Importance Value Index etc were determined for both the sites. Regeneration status of tree species was analysed by developing population structures. Species richness (tree as well as shrub) was high in disturbed site (11 to 20) as compared to protected site (9 to 11), and in both the sites the species richness was maximum at hill slope. Among the tree species Quercus floribunda was dominant with highest value of IVI in protected site. Contrary to this, Quercus lecotrichophora was dominant in disturbed site at hill base and hill slope, while Q. floribunda was dominant at hill top site. Tree density ranged from 780 to 1000 trees ha^-1 in protected site and from 260 to 780 trees ha^-1 in disturbed site.  In both the sites, Q. leucotrichophoraand Q. floribunda have higher proportion of individual in younger girth classes (seedlings and saplings), indicating expanding type of population structure. However, conversion into higher girth classes was more prominent at protected site as compared to disturbed site. Thus, it can be concluded that oak species of Kumaun Himalayan region have ability to regenerate when anthropogenic pressures are negligible. 

Key words: Basal area, density, diversity, girth class, population structure, regeneration.