MODERN POLLEN RECORD ON BAT GUANO DEPOSIT FROM SIJU CAVE AND ITS IMPLICATION TO PALAEOECOLOGICAL STUDY IN SOUTH GARO HILLS OF MEGHALAYA, INDIA

Abstract: Meghalaya is well known for its rich tropical biodiversity and numerous natural caves. The Siju Cave of Meghalaya, also known as cave of the bat, is among the longest caves on the Indian subcontinent. The palynological study of fifty bat-guano samples from Siju Cave and of thirty surface soil and moss cushion from the area immediate surrounding the cave reflects the close similarity between the modern pollen and vegetation in the region in the two areas sampled. The resulting palynodata comprise mainly the native flora, dominated by riparian taxa like Duabanga, Syzygium, Careya, and Ficus, along with evergreen and deciduous elements in the region. The evergreen taxa Mesua, Elaeocarpus, and Garcinia, along with Impatiens, reflect the high precipitation in the region. The climate of the region and the vegetation are strongly influenced by the Simsang River, and the heavy rainfall results in the dominance of riparian taxa and other high-rainfall indicator taxa. The occurrence of pollen from Nepenthes khasiana, an endemic and endangered plant of Meghalaya, in bat guano is significant and may be due to its insectivorous and entomophilous nature. However, medicinal plants like Swertia chirata, Cinchona, and Rauvolfia are not encountered in the bat-guano sediments, despite their luxuriant growth around the cave, and these species could be avoided by the insects due to their alkaloid contain and bitter taste. The presence of highland taxa such as Pinus, Abies, Picea, and Larix in the bat guano deposit is significant and suggestive of high winds from higher altitudes, or the pollen may be introduced by the return of migratory Siberian birds during winter to the nearby Siju wildlife and bird sanctuary. The recovery of cerealia along with Areca catechu and Citrus pollen indicate the human activity in the region. The abundance of fungal remains, namely Meliola, Glomus, and Microthyriaceae along with degraded palynomorphs are suggestive of strong microbial activity under warm and humid conditions during sedimentation in the region. The main objective of this study is to identify the potential of bat guano for palaeoecological research and as supportive data for surface and sedimentary soil profiles in the South Garo Hills of Meghalaya. The palynodata from the bat guano of the Siju Cave provides a useful source for palaeoecological information for the South Garo Hills, where intensive natural and human-caused forest fires, heavy rainfall, and soil erosion occur every year and there is a relative scarcity of the lake, wetland, and swamp habitats that normally preserve pollen

Modern botanical analogue of endangered Yak (Bos mutus) dung from India: Plausible linkage with extant and extinct megaherbivores.

The study reports the micro- and macrobotanical remains on wild Yak dung, providing evidence for understanding the diet, habitat, and ecology of extant and extinct megaherbivores. Grasses are the primary diet of the yak as indicated by the abundance of grass pollen and phytoliths. Other associated non-arboreal and arboreal taxa namely, Cyperacaeae, Rosaceae, Chenopodiaceae, Artemisia, Prunus, and Rhododendron are also important dietary plants for their living. The observation of plant macrobotanical remains especially the vegetative part and seeds of the grasses and Cyperaceae is also in agreement with the palynodata. The documented micro- and macrobotanical data are indicative of both Alpine meadow and steppe vegetation under cold and dry climate which exactly reflected the current vegetation composition and climate in the region. The recovery of Botryococcus, Arcella, and diatom was observed in trace amounts in the palynoassemblage which would have been incorporated in the dung through the ingestion of water and are indicative of the presence of perennial water system in the region. Energy dispersive spectroscopy analysis marked that the element contained in dung samples has variation in relation to the summer and winter, which might be due to the availability of the food plants and vegetation. This generated multiproxy data serves as a strong supplementary data for modern pollen and vegetation relationships based on surface soil samples in the region. The recorded multiproxy data could also be useful to interpret the relationship between the coprolites of herbivorous fauna and the palaeodietary, the palaeoecology in the region, and to correlate with other mega herbivores in a global context