Author : Banaticla, Maria Celeste N.

Summary : An altitudinal transect study was conducted at the Northeastern slope of Mt. Banahaw de Lucban. Forty-two (42) fern patches were sampled using the line transect method. Ninety-three (93) species under 47 genera and 24 families were found in the study area. The most represented families are Polypodiaceae (11 spp.), hymenophyllaceae (11 spp.) and Aspleniaceae (9 spp.) while the most represented genera are Asplenium (9 spp), Lycopodium (5 spp.) and Selaginella (5 spp). Twelve (12) species or 14% of the total number of species are endemic to the Philippines and majority are Malesian elements. Cluster analysis and principal component analysis (PCA) classified pteridophyte vegetation on Mt. Banahaw de Lucban into 5 zones : Zone 1, Cyathea contaminans - Dicranopteris - Nephrolepis - Diplazium patches from 700 - 800 m a.s.l.; Zone 2, Sphaerostephanos hirsutus - Selaginella delicatula patches from 750 - 900 m a.s.l.; Zone 3, Cyathea philippinensis - selaginella patches from 900 - 1200 m a.s.l.; Zone 4, Cyathea philippinensis - Cyathea callosa - Asplenium cymbifolium - Selaginella cumingiana patches from 1200 - 1550 m a.s.l. and Zone 5, which is further divided into sub-zone 5A, Cyathea callosa - Cyathea loheri - Hymenophyllaceae patches from 1550 - 1800 m a.s.l. and Sub-zone 5B, Cyathea loheri - Cephalomanes meifolia patches from 1800 - 1875 m a.s.l. The alignment of these pteridophyte zones with the woody species zones reported by Esperanza (1993) implies that pteridophyte distribution may be dependent on the floristic composition and structure of vegetation along the slope. Species diversity gradually increases with elevation, peaking at 814 - 886 m a.s.l.. The presence of many different microenvironments as a result of the stratified vegetation structure of the secondary forest, offers a variety of niches for the pteridophytes. Fern patches located in grasslands and exposed areas exhibit lower diversity indices.