Modern pollen spectra from the Pala Wetland Reserve Forest, Siaha District, Southern Mizoram, north-eastern India

Abstract

This study is an attempt to evaluate the relationships between vegetation and modern pollen rain in Siaha District, Southern Mizoram, India, as a contribution to palaeoecological research. A set of 21 pollen substrates (surface soil and moss pollsters) were obtained from the vicinity of Pala Lake, the biggest natural lake in Mizoram. Two thick spider web samples were also incorporated to measure the degree of trapped airborne palyno-debris as compared to the moss-soil data. The total pollen rain reflects the site-to-site variation in the pollen assemblages as shown by their abundances – 38%, 26% and 27% from the forest, forest margin and open land, respectively. The spider web samples also contribute 9% of palynomorphs to the total pollen assemblage. The total pollen rain revealed the dominance of non-arboreal pollen (NAP: 56%) over arboreal pollen (AP: 27%). The data showed a partial correlation with the extant woody vegetation; however, two major arboreal taxa – Dipterocarpus and Xerospermum – are under-represented despite their prominence in the near vicinity. The presence of highland taxa such as Tsuga and Carya indicates long-distance pollen transport. The abundance of monolete and trilete ferns also suggests a prevalent humid depositional environment. Fungal spores mainly constitute the non-pollen palynomorphs (NPP) assemblage. Low representation of dominant tree taxa in the pollen assemblages, even in the samples proximal to the forest, can be attributed to the entomophilous nature of the trees (Emblica and Artocarpus species). The extant palynoflora recovered in different surface substrates are suggestive of differential pollen production, dispersal and deposition.