Abstract:
Lichens are composite organisms consisting
of a symbiotic association of a fungus
with a photosynthetic partner, either a
green alga or a Cyanobacteria, grow in
diverse climatic conditions and on equally
diverse substrata and are widely distributed
in almost all the phytogeographical
regions of the world. An ‘annotated
checklist’ published by the Botanical
Survey of India (BSI) documents 2303
species belonging to 305 genera and 74
families in India1.
Lichens are a major section of species
that are sensitive to changes in atmospheric
nutrient conditions2 and have
been used as bioindicators of pollution
over a long period of time, especially
sulphur dioxide (SO2)3. Fruticose lichens
are known to be the most sensitive to air
pollution, followed by foliose and crustose
forms. The vanishing of sensitive
lichen species due to changes in microclimatic
conditions and air pollution has
been reported from Indian cities of Bangalore4
and Kolkata5. Due to the fast rate
of disappearance of flora for a range of
reasons like habitat loss, air pollution,
changes in the microclimatic conditions
and uncontrolled harvest, lichen biologists
have initiated a discourse to creating
‘protected areas’ for conservation of
lichens6. Systematic studies on lichens in
India, however, are still sporadic. More
so, there are instances of limited studies
in the northeastern region of India, which
is also a biological hotspot.