Diversity and Distribution of Vascular Epiphytic Flora in Sub-temperate Forests of Darjeeling Himalaya, India

Abstract

Aims: This communication deals with the diversity and distribution including host species distribution of vascular epiphytes also reflecting its phenological observations.
 Study Design: Random field survey was carried out in the study site to identify and record the taxa. Host species was identified and vascular epiphytes were noted.
 Study Site and Duration: The study was conducted in the sub-temperate forests of Darjeeling Himalaya which is a part of the eastern Himalaya hotspot. The zone extends between 1200 to 1850 m amsl representing the amalgamation of both sub-tropical and temperate vegetation. The study was conducted during the year 2018-2019.
 Methodology: Process of random sampling collection was followed. Host trees with CBH >30 cm were identified and percentage of distribution of epiphytes in the host tree was analyzed and divided into two zones depending on the abundance of epiphytes. Data for the epiphytic plant specimens were collected in the field. Exsiccates were made with the collected voucher specimens and were deposited at the Calcutta University Herbarium (CUH) following the conventional methodology. Study on the taxa are based on their host tree distribution, micro-habitat and phenological status. The location and altitude of the study sites were recorded by global positioning system.
 Results: A total number of 115 species under 70 genera and 31 families have been identified with 65% other vascular angiosperms (basal angiosperms and eudicots) and 16% monocots. Orchidaceae among the monocots represented 36% with 41 species and 18 genera. Ferns and lycophytes include 25% of the diversity with 29 taxa under 6 families. Most favorable host trees were Ficus auriculata Lour., Ficus neriifolia Sm., Saurauia nepalensis DC., Erythrina variegata L., Macaranga denticulata (Blume) Müll. Arg., Cryptomeria japonica (Thunb. ex L.f.) D. Don and Engelhardia spicata Lechen ex Blume.
 Conclusion: The other vascular angiosperms preferred wet monsoon for flowering whereas spring season was most favourable for Orchidaceae. Although a healthy number of vascular epiphytes have been identified, a number of threats are still prevailing in the regions which are mostly anthropogenic. Proper collaborative strategies have to be maintained for its conservation.