A comparative assessment of pollen in modern vegetation and bat guano in Pipulbari Cave of Meghalaya, India

Abstract

This study presents a palynological examination of modern bat guano to understand the quality of pollen preservation in relation to the extant vegetation in and around the vicinity of the Pipulbari Cave. Surface soil samples from the nearby forest, cropland and wetland areas were also studied for the comparison of pollen rain in relation to the current vegetation and landscape in the region. The pollen data recovered from the forest are indicative of tropical mixed deciduous forest composed of Shorea, Salmalia, Mesua, and Duabanga which exactly conforms to the extant vegetation in the region. The wetland vegetation was characterized by the consistent recovery of marshy and aquatic taxa including Cyperaceae, Polygonum, and Nymphaea in the pollen assemblage. The pollen preserved in cropland was characterized by the presence of cereal and Brassica. The pollen data from the modern bat guano samples display a relative dominance of the forest constituents as compared to wetland and cropland vegetation which reflects the preferential foraging of bats in dense forest areas. A multivariate principal component analysis (PCA) was applied to quantify data obtained from pollen frequency analyses of different areas inside Pipulbari Cave, which clearly revealed a significant group variation in vegetation type on the basis of dispersal and deposition of pollen in surface soil and bat guano samples. The pollen data from the modern bat guano samples are shown to provide a reliable basis for paleoecological reconstructions if they were to be based on the modern pollen analog method.