Evidence of deterioration in phytodiversity of Itanagar Wildlife Sanctuary, Arunachal Pradesh, India based on palynological evidence

Abstract

The pollen–spore assemblage and their preservation status study based on 25 surface samples from different sites of Itanagar Wildlife Sanctuary, Arunachal Pradesh is documented. The survey was based on 25 surface samples from different sites of the sanctuary with a view to assess actual status of pollen preservation. The pollen assemblage depicts predominance of the nonarboreals over arboreals which do not fully match the present vegetation of the sanctuary. However, the occurrence and relative abundance of both deciduous and wet evergreen forest complex though in low frequency are of great significance towards its existence. Arecaceae pollen probably belongs to Arenga and Livistona despite their absence in surrounding vegetation. The presence of cerealia and other cultural pollen, viz. Chenopodiaceae and Xanthium are suggestive of the anthropogenic activity in and around the study area. The enhanced fern allies especially Osmunda, Cheilanthes, Gleichenia, Dipteris and Pteris pentagyna are supposed to be of subtropical–temperate in origin coupled with fungal complex (Glomus, Xylaria and Microthyriaceae) indicate humid depositional environment in the basin. Prevalence of rich organic matters festooned with fungal remains may be attributed due to relatively higher rates of weathering and erosion of the hinterland influenced by enhanced SW monsoon during the time of deposition. The incidence of degraded palynomorphs indicates aerobic microbial diagenesis of rich organic debris during sedimentation. The overall palynological result hints a deteriorating scenario of wildlife sanctuaries and associated region in recent times.