Is bat guano a potential pollen trap? A comparative assessment from conventional soil and moss substrates from Eraaning Cave of Meghalaya, India

Abstract

This study examines the pattern of preservation of pollen and non-pollen palynomorphs on bat guano samples in Eraaning Cave in relation to the current vegetation of the surrounding Garo hills of Meghalaya. It is observed that, the recorded pollen data does reflect the tropical mixed deciduous forest with an admixture of riparian and evergreen plant taxa from the local and regional vegetation. The presence of evergreen and riparian taxa namely, Mesua, Schima, Duabanga, and Syzygium in the pollen assemblage is strongly indicative of the high rainfall in the region. The recovery of fern and fungal spores in the pollen assemblage also reflects the warm and humid climatic condition in this region. The forestland and open-land samples from the vicinity of the cave were also studied to understand the nature of pollen preservation in relation to the bat guano samples. The presence of cereal, Areca, Psidium, and Citrus along with Melastoma pollen in both bat guano and open-land samples is indicative of the anthropogenic activities in and around the study area. Multivariate principal component analysis (PCA) and box plot were applied to the quantified data obtained from pollen frequency analyses which clearly revealed a significant variation and similarity in vegetation types among the surface samples collected in and around Eraaning Cave. The generated pollen data from the bat guano, forestland, and open-land samples reveals that, bat guano in cave sediments provides a reliable substrate to understand the modern pollen and vegetation relationship and can fruitfully be utilized as a baseline for the reconstruction of the palaeoecology in the Garo hills of Meghalaya. The study also suggested that the bat species utilized the mixed vegetation composition and different landforms as their preferred habitats as demonstrated by the pollen data from the bat guano samples.