Leaf non-structural carbohydrates and leaf dry weight per area in three altitudinal populations of Espeletia schultzii Wedd

The leaf non-structural carbohydrate (NSC) content and total non-structural carbohydrate content (TNC) were measured on a dry weight basis and on a leaf area basis in three altitudinal (3100, 3550 and 4200 m a.s.l.) populations of E. schultzii. The values of leaf dry weight per area (LWA) increase with altitude. The leaf non-structural carbohydrate content (expressed as g/kg dry weight) does not show statistically significant difference among populations, but the values expressed on an area basis (g/m(2)) show a statistically significant increase with altitude. Significant correlations were observed between LWA and TNC (r(2) = 0.65); insoluble carbohydrate (r(2) = 0.78); total soluble carbohydrate (r(2) = 0.53); reducing sugars (r(2) = 0.47) expressed on area basis. Correlations between LWA and NSC for any fraction and TNC on a dry weight basis were not significant. It appears that along this altitudinal gradient the leaf area is more affected than the leaf dry weight. Since the NSC is known to play a role in the freezing tolerance of plants, the results indicate that the freezing tolerance does not change among the populations along the gradient.