Ecological, Social and Commercial Role of Lichens in India with ...

Acdemia Arena 2010, Supplement 0201
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tip of the twigs shows less number of individuals. There is a great decrease in lichen
abundance with decreasing twig diameter.
The Parmelioid genera Everniastrum cirrhatum, E. nepalense and parmotrema nilgherrense
with 18, 9 and 10 individuals respectively, dominate the twigs towards the tips while individual of
other lichen exhibit their poor presence there.
The luxuriance of lichen growth on Quercus twigs may possibly be attributed to the
retention of moisture because of their hanging position. The flow of rain water and that of the
melting snow along the hanging twigs perhaps provide greater exposure to moisture. However,
according to Pike et al. (1975), twigs being at the edge of the trees canopy receive higher levels of
light than most of the remaining surfaces of the tree. Rainfall strikes foliage and twigs directly and
these receive additional water which drips from higher branch system. Because of the exposure,
and the low water holding capacity of the bark, twigs dry out quickly after rainfall. Twigs can
however hold a considerable load of snow during and after wet snow fall.
Wolseley and Pryor (1999) studied the lichen communities on twigs of Quercus petrarea in
Welsh woodland site and concluded that there is a correlation between environmental condition and
lichen communities of twigs. Roughness, bark pH and chemistry of twigs, amount of moisture as
rain tracks or humidity, degree of illumination, aspect and illumination of the surface, acidification
of the atmosphere are the specific characteristics of the substratum influence the growth of lichens
on twigs. The environmental conditions were more or less similar in all the stands of the study area
except the aspects of the illumination at few sites. Both Parmelioid and fruticose lichens were
evident on the twigs than elsewhere. The crustose lichens were abundant on apical areas of the
young twigs and covered a substantial area. According to Essen et al (1996), the fruticose
pendulous species (Alectoria and Bryoria) are highly sensitive to forest practices and are strongly
related to age of branches while type of forest has no significant effect on foliose lichens. Similarly
all the three Oaks in the study area share growth of common foliose and fruticose lichens.
McCune (1993) while studying the epiphyte biomass in three Pseudotsuga-Tsuga forest in
western Oregon and Washington, recorded greater epiphyte biomass in old-growth stands than the
younger stands. Similarly in the present study Q. semecarpifolia comprised of mostly the oldgrowth
forest stands exhibited greater number of individuals. Based on the ecological roles rather
than taxonomy the epiphytic lichens of the Oak trees can be grouped into Parmelioid
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