Differences in drought resistance among 3 deciduous oak species grown in large boxes

Abstract

Summary — The purpose of this study was to explain large differences in growth and decline of the pedunculate oak (Ouercus robur L) and the sessile oak (Q petraea Liebl) observed in the forest as a result of drought. In addition, northern red oak (Q rubra L) was compared with the 2 indigenous oaks. The effects of controlled soil water deficits on growth and water relations of young plants of these 3 species grown in large boxes have been studied. The plants were old enough to have developed normal root systems. Two species were planted in each box, and submitted to very similar patterns of water stress. Predawn leaf water potential, stomatal conductance, net assimilation rates, shoot elongation and mortality were monitored. The effect of an overall improvement in mineral nutrition on these parameters was also tested. During water deficit (decrease in predawn leaf water potential), the pattern of decrease of gas exchange was similar for the 3 species. Thus, their ability to limit water deficit by reduction of transpiration was similar. On the other hand, shoot growth of Q rubra was more reduced than that of Q robur for similar predawn leaf water potential; growth of Q petraea was the least sensitive. However, increase of mineral nutrition improved the growth of both Q robur and Q rubra, but not that of Q petraea. For the 3 species, no mortality was noted as long as predawn leaf water potentials remained > -3.6 MPa. Below this limit, the mortality rate was highest in Q robur, Q petraea and lowest in Q rubra. These differences in mortality between species are due to differences in tolerance to water stress, not in avoidance.drought / growth I gas exchange I dieback I fertilization I Quercus Résumé — Différences dans la résistance à la sécheresse de 3 espèces de chêne à feuilles caduques, cultivées en conteneurs.

Réponse des semis de Quercus robur L. à l’asymétrie de lumière Nord-Sud dans les trouées des forêts inondables en Slovénie

“…Here a combination of direct light, low precipitation due to interception, and root competition could have a drought effect. Quercus robur was reported as more sensitive to drought stress [37] compared to Q. petraea, but it seems more resistant than competing understory vegetation. This could be attributed to a deep root system, which can rapidly develop in a few years [13,17,23].…”

Interactive effects of drought and pathogens in forest trees

“…The analysis of the oak decline which occurred in France following the severe 1976 drought showed that only Quercus robur was affected [14]. This could be explained by a higher sensitivity of Q. robur than Q. petraea to water deficits and a higher susceptibility to root pathogens [109,161,205].…”

Morphological and physiological responses of oak seedlings (Quercus petraea and Q. robur) to moderate drought

“…Therefore, they tend to gain dominance over beech mainly at sites with more extreme soil moisture conditions [8]. Although, compared to the sessile oak, the pedunculate oak was found to have a larger water requirement [17] and to be more sensitive to drought stress [4,27], this species also occurs at sites with low water supply, e.g. on nutrient-poor sandy soils (Betulo-Quercetum roboris; [29]), or on plateaus and exposed slopes of well-drained limestone hills (xerothermic mixed oak forests; cf.…”