Dynamique de l'eau dans une chênaie (Quercus petraea (Matt.) Liebl.) en forêt de Fontainebleau

Abstract

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 Pi; transpiration was of 76.4% of Pi (T = 288.4 mmlyear). 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, TlETP increases in spring from 0.44 to 0.83) and soil-water depletion (T/E'rP ratio was not reduced from field capacity (Rcc 168 mm) until 65% of R cc (108 mm), and then decreased quickly to near zero (0-0.2) at wilting point or 37°/ of Red.forest -water balance -through fall -net interception -stemflow -transpiration -Quercus petraea (Matt.) LiebL -Fontainebleau forest

Water use in neighbouring stands of beech (Fagus sylvatica L.) and black alder (Alnus glutinosa (L.) Gaertn.)

“…This corresponds also to the recent study of Martin et al [25], who demonstrated that an infinite surface conductance (representing wet leaf surfaces) would increase forest evaporation severalfold under a given radiation input. The observed amount for E i of 16 % of P G for beech and alder forest is even lower than the 29 % reported by Nizinski and Saugier [29] for the above-mentioned oak forest of Fontainebleau, but matches a range that is typical for broadleaved forests in temperate regions [18,30].…”

“…Whilst some authors explicitly set this component of the forest water balance to zero [29,31,42], others put emphasis on the significant amount of soil evaporation even under a closed forest canopy [41], especially under wet climatic conditions. Kelliher et al [19] reported that 10-20 % of the total evaporation in a closed Nothofagus forest came from the soil surface.…”

A Linking Test that establishes if groundwater recharge can be determined by optimising vegetation parameters against soil moisture

“…Hence, it is suggested that Calder et al (2002) over predict evapotranspiration and under predict interception. The question addressed in this paper is to determine the reasons why Calder et al (2002) found such dissimilar results as compared to Nizinski and Saugier (1989).…”

“…Calder et al (2002) also optimised the winter interception parameters and found that interception was equal to 18% of the annual rainfall. However, Nizinski and Saugier (1989) measured oak interception and found it to be equal to 25%. Hence, it is suggested that Calder et al (2002) over predict evapotranspiration and under predict interception.…”

“…Nevertheless, we believe that the value of β was over predicted. Bobay (1990), Nizinski and Saugier (1989) indirectly measured the crop factor of a chestnut coppice near Orsay and of an oak forest near Fontainebleau (50 km south of Paris), respectively. They found a much lower value of 0.3 for β in winter, which is expected since the shedding of leaves by deciduous trees considerably reduces their water loss.…”