Tucker, G. F.; Emmingham, W. H. 1977. Morphological changes in leaves of residual western hemlock after clear and shelterwood cutting. Forest Science. 23(2): 195-203.
The change in microclimate associated with clear and shelterwood cutting hadmarked effects on the leaves of residual western hemlock trees. In a new clearcutting, oldneedles abscised prematurely and needles that formed during the first season of exposurewere smaller than normal, apparently because of water stress. Needles formed in the sec-ond season had thicker palisade mesophyll, a smaller ratio of surface area to weight, andmore stomata per unit surface area. Leaves that had developed in the shade and were laterexposed showed a slight increase in thickness, probably because of increased palisademesophyll development. These changes in leaf area and structure were toward a config-uration which was more efficient in utilization of light and water in a clearcutting. Hem-lock saplings left in a shelterwood suffered less needle loss and mortality, but they stilldeveloped needles adapted to full sunlight, suggesting a shelterwood as a beneficial treat-ment for understory hemlock. FOREST SCI. 23:195-203.
ADDITIONAL KEY WORDS. Palisade mesophyll, Tsuga heterophylla, microclimate, stomatalfrequency, ratio of surface area to weight.