Based on vegetation types orchids are found in following types of vegetation in Uttara Kannada. • Evergreen-semievergreen forests In all the above habitats except grasslands both terrestrial and epiphytic orchids are found. In Uttara Kannada district, though the altitude does not exceed 1300 m, it has 100 species, which is highest for the state. On the contrary, Kodagu and Chickmagalur districts have the altitudes ranging up to 2000 m but the number of orchids is 69 and 59 respectively (Rao T A., 1998). Niche profile Those orchids occupying the highest canopies of the emergent trees are xerophytic and tolerate long periods of high intensity of light that approximates steady state for their growth. However between crown canopy and crown base in the understorey where rapid fluctuation of sun and shade often predominate, maximum numbers of orchids are found growing (Sciophytes). The third category of orchids is truly shade tolerant and occupies the tree trunk or stump portions of the understorey (mesophytes). The orchids under the fourth ecological group are differentiated in their growth on soil either as an autophyte or saphrophyte. The epiphyte is generally tolerant to changes or vagaries of climatic changes by their adaptive habits and specialized roots, in addition to waxy coatings and succulence of varying dimensions. These have made them tolerant to xerophytic amplitudes of varying degree including physiological drought condition as an excessive rainfall during rainfall during monsoons especially, southwest monsoon. The heavy rainfall and high temperature prompt the atmosphere to reach saturation point. The optimum condition for good growth for orchids hovers around 250 C which is the normal condition in the equatorial region with very little variation. |
