Patterns of water potential among forest types of the central Himalaya

Water potential (psi) of soil and trees was measured in 16 forests from 450 to 2310 m elevation in the Kumaun Himalaya, during a two-year period. Pred awn psi, averaged across all species at a site was high (i.e, not stressful ) at low elevations and variable at higher elevations. The incidence of low psi at high elevations was opposite the usual pattern elsewhere. Midday ps i varied similarly. Patterns of plant and soil psi differed. psi values, es pecially in summer and winter, were severe enough to affect tree growth adv ersely.