Stomatal response of Quercus pyrenaica Willd to environmental factors in two sites differing in their annual rainfall (Sierra de Gata, Spain)

Abstract

Summary — Quercus pyrenaica natural forests located in the Sierra de Gata (Salamanca Province, Spain) were studied. Two permanent sampling sites were selected at the two extremes of a rainfall gradient in this area. Diurnal courses of transpiration rate, stomatal conductance and leaf water potential were determined approximately every 2-3 weeks in 1991 and 1992 during the active leaf period at different levels in the tree canopy. Current variations in photosynthetically active radiation (PAR) incident to the leaf surface, air and leaf temperature, vapour pressure deficit (VPD) and soil moisture were also measured. Boundary-line response curves between leaf conductance and four variables were studied to determine the general stomatal response patterns. Leaf

Groundwater and Light Conditions as Factors in the Survival of Pedunculate Oak (Quercus Robur L.) Seedlings

“…In Q. pyrenaica reduction in stomatal conductance became evident below À2.0 MPa (Rico et al 1996), while in Q. pubescens and Q. ilex it occurred only below À4.0 MPa (Methy et al 1996).…”

Drought resistance of Quercus pubescens as a function of root hydraulic conductance, xylem embolism and hydraulic architecture

“…In recent years, increasing attention has been paid to the strategies adopted by different Quercus species to withstand drought, in view of the ecological importance of oaks in the reforestation of degraded areas in Europe (Lo Gullo & Salleo, 1988 ;Salleo & Lo Gullo, 1990 ;Cochard et al, 1996 ;Nardini et al, 1996 ;Radoglou, 1996 ;Rico et al, 1996). Most of these studies report seasonal and diurnal changes of water relations parameters measured in leaves and stems such as leaf water potential (ψ L ), conductance to water vapour (g L ), relative water content (RWC) and, more recently, vulnerability to xylem cavitation of stems (Tyree & Sperry, 1989 ;Lo Gullo & Salleo, 1993) and leaves (Kikuta et al, 1997).…”

The effect of tree height on crown level stomatal conductance

“…2) , and one class representing the higher irradiance.With nine trees analysed, this resulted in 54 subsets of data. Each subset was subjected to a boundary line analysis, designed to select data representing maximum conductance for each tree in each Q o class along the range of D (Dye & Olbrich 1993;Rico et al 1996;Martin et al 1997). The upper boundary line was derived by: (1) partitioning G Si data of each light class into 0·2 kPa vapour pressure deficit intervals, (2) calculating the mean and standard deviation of G Si in each interval, (3) removing outliers (P < 0·05; Dixon's test according to Sokal & Rohlf 1995), (4) selecting the data falling above the mean plus one standard deviation, and (5) ).…”