Ecological wood anatomy ofAlnus nepalensis (Betulaceae) in East Nepal

Wood anatomical characters ofAlnus nepalensis growing in East Nepal are evaluated against three non-anatomical factors: tree height, diameter at breast height (DBH), and altitude. Samples were taken from the outermost part of the trunk of five canopy trees at 11 localities between 790 and 2,740 m above sea level. Tree height ranged from 10 to 28 m, and DBH ranged from 15 to 80 cm. Altitude and tree height are correlated with all the vessel characters studied. Among wood anatomical characters, vessel characters measured from cross sections are strongly correlated with one another, and are also correlated with vessel element and fiber-tracheid length. Multiple regression analysis using non-anatomical factors as independent variables resulted in significant correlation at 1% level in all pore characters, vessel element length, perforation plate bar number, and fibertracheid length. Regression coefficients of significant regressions are usually largest for altitude. For wood structure ofAlnus nepalensis in East Nepal, 23 to 42% of the variation is affected by non-anatomical factors. The large contribution of altitude is considered to be an indirect measure of the effect of temperature.