Oak sprouts grow better than seedlings under drought stress

Abstract

This study focused on the comparison of two contrasting forest regeneration types and their susceptibility to drought stress. Transpiration and biomass production were studied on young sessile oak trees Quercus petraea (Matt.) Liebl. regenerated as sprouts and seedlings, and grown in a coppice experimental site in the Czech Republic. Biomass production was estimated using destructive methods, while transpiration was derived from sap flow measurements and assessed according to the plant biometry and microclimatic conditions. Sprouts were characterized by a significantly higher diameter, height, leaf area and above-ground biomass and by a lower wood density as compared with seedlings of the same age. Moreover, the sap flow of sprouts was higher than that of seedlings, which was explained by the plant dimension. Transpiration, expressed as sap flow scaled to plant leaf area, did not differ between seedlings and sprouts when soil water was not limiting. However, during drought periods, when soil water potential dropped below -1.4 MPa, sprouts transpired significantly more than seedlings. Our results confirm that sprouts have access to a larger water pool via the old stump root system and are able to draw more water under drought. Moreover, sprouts seemed to be less susceptible to water limitations than seedlings of similar age. Less influence of drought on sprouts may partially explain their higher above-ground biomass production. Based on our results, coppice could be an appropriate management system to be adopted in sites characterized by frequent or extreme drought periods.

Keywords

• Drought Stress
• Sap Flow
• Transpiration
• Biomass Production
• Sessile Oak
• Coppice
• Sprout
• Seedling