1995-96 - Birbal Sahni Institute of Palaeobotany

BSIP
climate during this period. Between 1500 to 900 yrs B.P. the cxpansion of broad-leaved
clcments such as Betula, Salix, Rhododendron into these steppcs suggests the amclioration
in climate. Thereafter, the reversal of cold and dry climate took placc as cvidenccd by the
improvement in Ephedra, .1zmipen,s and grasses and a corresponding decline in the broadleaved
elements.
Programme 7.3
Objective
M.S. Chauhan
Pollen analysis of 4 surface samples gathered from the vicinity of Chharaka Tal (Sat
Tal), Garhwal Himalaya has revealed the exceedingly high values of Pinus followed by
Cedrus, Abies, Picea, Quercus, Alnus, Carpinus, Betula, etc. reflecting more or Icss the
surrounding vegetation. The non-arborcals such as Poaceac, Cyperaceae, Artemisia, Cheno/
Ams, Asteraceae, Ranunculaeeae are also recorded in good frequencies. However, the over
representation of Asteraceae in one of the samples denotes the abundance of the members of
this fanlily.
M.S. Chauhan & Chhaya Sharma
Constructcd pollen spectra of air catches from Chaurangi-KJlal and Nachiketa Tal,
Garhwal Himalaya. Studies reflect more or less surrounding vegetation except for Pinus
which deem to be drifted.
History of mangrove vegetation in India
Asha Gupta & Chhaya Shanna
Tostudy palynostratigraphy and Di'persed Organic Mafler analysis
ojthe sedimentsjrom Chilka Lake in Mahanadi-Brahmani-
Baitarini deltaic region in Orissa
Twenty samples of Dangmal profile collected from thickets of mangrove forest at
Bhitarkanika, Mahanadi Delta have been palynologically investigated, and exhibited rich
occurrence of palynodebris such as pollen, spores, diatoms, dinoflagellate cysts,
microforaminifera, pseudoschizea, etc. The core-mangrove taxa encountered are
Rhizophora, Heriliera, Sonneratia, Avicennia, Excoecaria, Aegia/itis, etc. indicating conducive
environment for growth and development of mangroves.
Accomplished the pollen analysis of 1.5 m deep profile dated back to 20,000 yrs
B.P. from Andaman and Nicobar Islands. Three phases of vegetation development have
been recognised : Phase I, between depth of 110.0-80.0 cm, covering a time span betwecn
20,000-18,000 yrs B. P., recorded the existence of brackish water Heritiera forest, wherein
Avicennia, Lumnilzera, Acrostichum, Rhizophoraceae, Palmae had made their presence in
moderate values.
Phasc II, between depth of 80.0-45.0 cm, covering a time span between 18,000­
12,000 yrs B.P., had witnessed a shift in vegetation from brackish water Heritiera forest to
salt-marsh vegetation wherein halophytes like Salsola, Suaeda, Porteresia and sedges
colonised. The occurrence of hinterland taxa such as Holoptelea, Salvadora, Emblica,
Oleaceae, Fabaceae, etc. have also been recorded.
Phase !II, between depth of45.0-0.0 cm covering a time span of 12,000 yrs B.P.,
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