Plant Nutritional Status Explains the Modifying Effect of Provenance on the Response of Beech Sapling Root Traits to Differences in Soil Nutrient Supply

Abstract

Forests dominated by beech (Fagus sylvatica L.) cover large parts of Europe where they occupy a broad ecological niche in terms of soil fertility. This indicates a large potential to adapt to different soil conditions over long time periods. Recent changes in tree mineral nutrition across Europe raise the question to what degree beech can acclimate to changing soil conditions in the short term. In this study, we aimed at assessing the plasticity of root traits and rhizosphere properties of young beech trees from populations that are adapted to either high or low nutrient supply, when growing in soils differing in their fertility. We sampled beech saplings from two forest sites of contrasting nutrient supply, most distinctly in terms of phosphorus. We grew them for 2 years in rhizoboxes in mineral soil either from their own site or from the other site. We assessed the influence of the factors "plant origin" and "current soil" on root traits and rhizosphere properties. Fine root traits related to growth (biomass, length), architecture (branching), and morphology (diameter) responded strongly to the factor "current soil." Provenance (factor "plant origin") modified the response. The modifying effect was consistent with an influence of the plant status in those nutrients, which were not in sufficient supply in the soil. An additional genotypic difference in the sensitivity of the beech saplings to different soil nutrient supply could not be excluded. Fine root parameters normalized for length, mass, or volume (root tip density and frequency, specific root length and area, and root tissue density) did not differ among the treatments. Differences in percentage of mycorrhizal root tips and rhizosphere parameters related to phosphorus mobilization potential (pH, abundance of organic acid anions, and phosphatase activity) were small and mainly determined by the "current soil." Provenance had only a minor modifying effect, possibly due to differences in the ability of the plants to transfer carbon compounds from the shoot to the root and the fungal partner. Our results indicate a high plasticity of young beech trees to adapt their root system to different soil nutrient supply, thereby also taking into account internal nutrient reserves.

Contrasting distribution of enzyme activities in the rhizosphere of European beech and Norway spruce

“…However, AP activity was higher in spruce than beech, regardless of the root size. This result was surprising because in beech, similarly to CBH and LAP, and in accordance with other studies ( Meller et al., 2020 ), AP activity was largely positively associated with root morphological parameters, particularly root mean diameter and root volume. We may explain this discrepancy through the complexity of factors that control the rhizosphere AP activity ( Nannipieri et al., 2011 ; Margalef et al., 2017 ; Nannipieri et al., 2018 ).…”

“…We may explain this discrepancy through the complexity of factors that control the rhizosphere AP activity ( Nannipieri et al., 2011 ; Margalef et al., 2017 ; Nannipieri et al., 2018 ). The physiological status of the plant ( Clausing et al., 2021 ), species or genotype identity ( Denton et al., 2006 ; Razavi et al., 2016 ; Ma et al., 2018b ; Meller et al., 2020 ), or soil phosphorus level ( Hofmann et al., 2016 ; Wang et al., 2022b ) contribute to AP activity in the rhizosphere.…”

Fine root biomass of European beech trees in different soil layers show different responses to season, climate, and soil nutrients

“…In Central Europe, European beech (Fagus sylvatica L.) is a dominant forest tree species stocking on a vast range of soil types (Leuschner, 2020). In beech forests, fine root biomass and turnover are highly variable, depending on the environmental conditions and soil depth (Kirfel et al, 2019;Meller et al, 2020).…”

Plant–Microbe Interaction: Aboveground to Belowground, from the Good to the Bad

“…The presence of certain acids in the soil (phosphatases, carboxylase) improved ion availability to the plant [ 55 ], and indirectly influenced N 2 -cycling. The absence of these acids in exudates will influence N availability in soils [ 56 ] explaining the difference in nutrient acquisition between plants. In addition, plants are not only influenced by its own exudates but are influenced by their neighboring plants.…”