Distribution of epiphytes, parasites and mistletoes on six species of Phorophytes in upper montane tropical forest of Darjeeling, West Bengal
Asok Ghosh* and Sanjib Saha**
*Department of Botany, Krishnagar Govt. College, Nadia (West Bengal), PIN-701101 (India) E-mail: asokcarex@rediffmail.com, asokcarex@gmail.com ** Post Graduate Department of Botany, Darjeeling Govt. College, Darjeeling (W.B.). PIN-734101 (India)
ABSTRACT
Epiphytes are an important aspect of tropical montane rain forests. In the tropical mountainous rainforest, the forest canopy structure is highly correlated with local topography. However, the relationships of forest canopy with canopy epiphytes of the studied area are poorely described and yet to be established. This study was conducted to know the distributional pattern of vascular and nonvascular epiphytes in upper montane tropical forest of Darjeeling, West Bengal. We examined the distribution of vascular and nonvascular epiphytes on six species of phorophytes (i.e. Alnus nepalensis, Magnolia campbellii, Platanus orientalis, Rhododendron arboreum, Thuja orientale and Quercus lamellosa) focusing on pattern on epiphytic distribution at different spacial scale (in four different zones viz. Zone-I= trunk; Zone-II= 1st order branches; zone-III= 2nd order branches and zone-IV= canopy of the phorophytes), epiphytic abundance amongst trees differing in size, and crown structure is associated with epiphyte abundance. Epiphyte functional groups were stratified vertically within the strand. Total epiphyte abundance increased with height classes. Large phorophytes (Quercus sp. and Magnolia sp.) have approximately twice the total epiphytic cover of medium trees (Thuja sp. and Rhododendron sp.). There were a decreasing abundance of epiphytes on phorophytes (Quercus sp.> Rhododendron sp.> Alnus sp.> Magnolia sp.> Platanus sp.> Thuja sp.). Vaccinoids and Orchids occur more or less on all the phorophytes. The Orchidaceae has its biggest abundance on all phorophytes and different species were found growing within zone-I and zone-II. Within phorophytes, plots closer to the 1st order branches and 2nd order branches had the greatest abundance of angiospermic epiphytes. The situation is different for Cryptogamic epiphyte functional groups (like Bryophytes and Pteridophytes not for lichens).