Leaf Phenological Responses of Juvenile Beech and Oak Provenances to Elevated Phosphorus

Abstract

The few studies dealing with leaf phenological responses to elevated nutrients in forest trees have given ambiguous results, i.e., while some reported delayed leaf-out and autumn leaf senescence, others reported advanced leaf phenology caused by increased nutrition. This study aimed to determine the effects of experimentally increased phosphorus (+P treatment) on the leaf phenologies of two juvenile provenances of common beech and sessile oak. Other objectives were to determine whether there were interspecific differences as well as intraspecific variations. Saplings were excavated in two mixed beech–oak stands and transplanted into four wooden boxes filled with a commercial soil substrate. Phosphorus fertilizer was added to two of the boxes, while the remaining boxes served as controls. Both species responded to +P treatment with advanced autumn leaf senescence in the first year of the experiment. Leaf senescence in common beech began significantly earlier, while in both species, the process was accelerated compared to that in the control. In the second year, the leaf senescence response to +P treatment was even more pronounced in both species. The +P effect on leafing phenology was absent in both common beech provenances and in an oak provenance. However, the other oak provenance showed advanced leafing, indicating the existence of intraspecific differences.

Effects of Drought, Phosphorus Fertilization and Provenance on the Growth of Common Beech and Sessile Oak

“…The effect of P fertilization or different concentrations of P in the natural soil on the growth of common beech and sessile oak is currently poorly investigated [47,67]. Previous research, mainly on common beech, has focused on inter-and intraprovenance differences in the uptake and internal P allocation mechanisms during the growing season and leaf phenology [47,62,[68][69][70][71][72][73]. Research on sessile oak has focused on the effect of P fertilization on leaf P concentration and total biomass production [67] or leaf phenology [73].…”

“…Previous research, mainly on common beech, has focused on inter-and intraprovenance differences in the uptake and internal P allocation mechanisms during the growing season and leaf phenology [47,62,[68][69][70][71][72][73]. Research on sessile oak has focused on the effect of P fertilization on leaf P concentration and total biomass production [67] or leaf phenology [73]. The effect of drought in interaction with P fertilization on the growth of common beech and sessile oak, nor other European forest tree species, has not yet been investigated.…”