Studies in the water relations of Pinus srlvestris in plantation conditions. II. The annual cycle of soil moisture change and derived estimates of evaporation.

Published online
22 May 1965
Content type
Journal article
Journal title
Journal of Applied Ecology

Rutter, A. J.

Publication language


Tensiometers and electrical-resistance blocks were used to measure water tensions and, indirectly, water contents of a sandy-clay soil under a 16-year-old plantation for 6 yr. The soil dried to about 2 m depth and soil-water deficits of 12-32 cm accumulated in summer. Water tensions in the root range rarely rose above 2 atm; even in a very dry summer they rose above 5 atm only in a limited part of the root range. Soil around tree bases appeared to dry more rapidly in summer, and to be re-wetted more rapidly in winter. Tensiometer readings were interpreted to indicate times when profile drainage ended in spring and was resumed in winter; it was assumed that in the intervening period total evaporation and precipitation were equal. The ratios of total evaporation estimated in this way to Penman's estimate of evaporation from an open water surface ranged from 0.98 to 1.20 with a mean of 1.10. This procedure neglected the possible contribution of capillary rise from the water table. An approximate estimate of capillary rise suggested that the ratio 1.10 should be increased by at least 0.10.

Key words