Pollen morphology of Himalayan Pinus and Quercus and its importance in palynological studies in Himalayan area

Abstract

Modern pollen grains of Himalayan Pinus ( P. roxburghii and P. wallichiana) and Quercus ( Q. semecarpifolia, Q. incana, Q. lanuginosa, and Q. glauca) were examined by scanning electron microscopy (SEM) in an attempt to identify fossil pollen grains of Himalayan Pinus and Quercus species. The exine sculpture of P. roxburghii is clearly rugulate and that of P. wallichiana is smooth or slightly rugulate. The exine sculpture of Q. semecarpifolia is scabrate and that of Q. glauca is microscabrate whereas other Quercus species examined have a microverrucate-scabrate sculpture on the pollen exine. These differences serve to identify fossil pollen grains of Pinus and some Quercus species, each of which is distributed in a specific climatic area. Pollen analyses on sediment samples obtained from the Kathmandu valley, Nepal were also carried out to evaluate the usefulness of SEM pollen identification. It was possible to detect climatic change only when SEM was used in addition to light microscopy (LM). The accuracy of the reconstruction of the Himalayan palaeoclimate by means of pollen analysis is improved when SEM is applied to the identification of Himalayan fossil Pinus and Quercus pollen grains.