Leaf size zonation pattern of woody species along the northeastern altitudinal gradient of Mount Makiling, Luzon Island, Philippines

Woody species sampled along trail linking UPLB to the peak were subjected to leaf size zonation study using cluster analysis from 150 to 950 meters above sea level (m asl) on the northeastern slopes of Mt. Makiling (1109 m asl). Eighty species representing 64 genera and 36 families were encountered within the study area. Cluster analysis using leaf size showed that four clusters existed: Zone I - mesophyllous and notophyllous, Zone II - mesophyllous, notophyllous and microphyllous, Zone III - mesophyllous and Zone IV - microphyllous. Largest leaf measuring 132000 mm(2) belonged to the Moraceae family (Artocarpus blancoi) and was collected at 250 m asl (Zone I), while the smallest leaf measuring 47.2 mm(2) belonged to the family Sabiaceae (Meliosma pinnata) and was collected at 450 masl (Zone I). Results show that large leaf sizes are mostly found in lower elevations and are replaced by smaller leaf sizes with increase in altitude; Emergence of a distinct zone within the first zone, attributed to previous intentional reforestation efforts of big-leafed exotic pioneer species and human encroachment, leading to the increase in mesophyllous leaves.