Transitional Pattern of Tree Leaf-Types from Tropical to Temperate Forests on Mt.Emei,Sichuan,China

【摘要】：正 The transitional pattern of tree leaf-types from tropical to temperate forests wasexamined on a subtropical mountain,Mt.Emei(3099 m asl,29°34.5’N,103°21.5’E),Sichuan,China.Three forest zones were identified physiognomically along the altitudinal gradient,viz.l)the evergreen broad-leaved forest zone(600-1500m asl),2) the mixed forest zone(1500-2500masl),and 3) the coniferous forest zone(2500-3099 m asl),and the zonal forest communities werecharacterized by their dominants and their floristic composition.The gradational changes ofevergreen broad-leaved forests toward their upper altitudinal limit were emphatically studied tofocus on the leaf sizes.Eighty-eight evergreen broad-leaved tree species were allotted into threeleaf-size classes:notophylls(48%),microphylls(36%),and mesophylls(16%),and the proportioncorresponds to that of northern limit forests of the subtropical/warm temperate evergreen broad-leaved trees.The leaf size of evergreen broad-leaved trees decreased with the increase in altitude.Additionally,the leaf size varied with forest stratifications;canopy layer was dominated bynotophyllous species while subcanopy and understorey layers were dominated by microphyllousspecies.Leaf size and its patterns varied with altitudes and forest stratifications,and the pattern ofleaf size features were help to understand the trend found in other mountains of eastern Asia.