Altitudinal zonation of pteridophytes on Mt. Banahaw de Lucban, Luzon Island, Philippines

Five altitudinal pteridophyte zones are established along the northeastern altitudinal slopes of Mt. Banahaw de Lucban, Quezon, Luzon Is., Philippines using cluster- and ordination analyses, namely: Zone 1, Cyathea contaminans - Dicranopteris-Nephrolepis-Diplazium patches at 700-800 m a.s.l.; Zone 2, Sphaerostephanos hirsutus var. hirsutus - Selaginella delicatula patches at 750-900 m a.s.l.; Zone 3, Cyathea philippinensis - Selaginella patches at 900-1200 m a.s.l.; Zone 4, Cyathea philippinensis - Cyathea callosa-Asplenium cymbifolium-Selaginella cumingiana patches at 1200-1550 m a.s.l. and; Zone 5 which is further divided into Sub-zone 5A, Cyathea callosa - Cyathea loheri-Hymenophyllaceae patches at 1550-1800 m a.s.l. and Sub-zone 5B, Cyathea loheri - Cephalomanes apiifolia patches at 1800-1875 m a.s.l. These pteridophyte zones coincide with the woody species zones of Mt. Banahaw de Lucban but differ significantly with the altitudinal fern zones of Mt. Makiling. Stepwise multiple regression analysis reveals that altitude exhibits a linear relationship with pteridophyte species distribution. Altitude and soil pH influence 65% of the variation in principal component 1 [PC1 = 0.0839 + 0.0010(altitude) -0.2072(soil pH); r = 0.8058] and 27% of the variation in principal component 2 [PC2 = 2.0453 -0.0005(altitude) -0.2560(soil pH); r = 0.5206]. Thirty-three (33) species are preferential to specific microenvironments along the altitudinal gradient, making them effective altitudinal zone markers and biodiversity conservation indicators for the forest ecosystem of Mt. Banahaw de Lucban.