Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: Variation of stomatal resistance with leaf age in Quercus petraea: effect on the soil-water balance of an oak forest. | 429s Ann. Sci. For. 1989 46 suppl. 429s-432s Forest Tree Physiology E. Dreyer etal. eds. Elsevier INRA Variation of stomatai resistance with leaf age in Quercus petraea effect on the soil-water balance of an oak forest J. Nizinski D. Morand and B. Saugier Laboratoire d Ecologie Végétale CNRS URA121 Bailment 362 Université de Paris-Sud 91405 Orsay Cedex France Introduction abaxial epidermis scanning electron microscope . In deciduous forests evapotranspiration follows variations in the leaf area index LAI . It is thus expected to reach a maximum in spring when the LAI reaches a plateau and when the soil water supply is adequate. From a detailed study of the soil-water balance over 3 yr we found that evapotranspiration reached a maximum nearly 1 mo after the leaf area index Nizinski and Saugier 1988 1989a b . We thus decided to study the effect of leaf age on stomatai resistance and on the morphology of the leaf epidermis. Materials and Methods Study site 2 stands of Q. petraea Matt. Liebl. in the Fontainebleau forest 1981-1983 and on the Orsay campus 1987 soil-water balance measurements rain gauges stemflow collars neutron probe stomatai resistance Delta T Mk-3 porometer in the middle of the day leaf size Delta T area meter and the observation of the Observations related to the soil-water balance Fig. 1 shows the strong decrease in stomatai resistance with leaf age expressed as the ratio of actual leaf area to its maximal area. All these values were obtained at high light intensity and ample water supply. This curve is repeated in Fig. 2b which shows a further decrease in stomatai resistance after full leaf development Fig. 2a . The decrease in stomatai resistance led to a progressive increase in the ratio of real transpiration to potential Penman evaporation T ETP from 0 at bud burst to about at the end of leaf growth and to at the end of June. Morphology of leaf epidermis Scanning electron microscopy of the leaf epidermis revealed 1 young leaves have Fig.
