Soil Water Balance in an Oak (Quercus petraea (Matt.) Liebl.) in Fontainebleau Forest

1989

S. 173-186

5 Abb., 24 Lit. Ang., Fr, Zfsg. En, Fr

Unselbständiges Werk

200014661

In a mature 120 years-old oak forest (Quercus petraea (Matt.) Liebl., mean tree height is 30m, stand density is 182 trees/ha, total basal area is 33.8 m2/ha, leaf area index is 4.38) gross precipitations, throughfall (rain gauges), stemflow (stemflow collar) and soil-water content (neutron probe) were measured weekly. Interception and transpiration were derived by the water balance equation method. Throughfall, interception and stemflow for three years were 70.6-28.8 and 0.6 per cent of gross precipitation (average value over 3 years) respectively, while those in nonfoliated conditions: 76.6, 22.4, 1.0% of Pi in foliated conditions: 65.5, 34.4, 0.1% of Po; transpiration was of 76.4% of Pi (T=288.4 mm/year). During the growing seasons T/ETP ratio is related to the evolution of the stomatal resistance with leaf age (at maximal leaf area index and negligible soil-water stress, T/ETP increases in spring from 0.44 to 0.83) and soil-water depletion (T/ETP ratio was not reduced from field capacity (Rcc=168 mm) until 65% of Rcc (108 mm), and then decreased quickly to near zero (0-0.2) at wilting point or 37% of Rcc).