Species‐specific differences in nitrogen uptake and utilization by six European tree species

Abstract

Species‐specific uptake and allocation mechanisms for N are scarce, in particular when trees are cultivated in potted soil under more natural conditions than in hydroponic culture. The objective of this study was to compare specific N‐uptake rates for economically and ecologically important tree species in Central European forests: pine (Pinus sylvestris), spruce (Picea abies), oak (Quercus petraea), beech (Fagus sylvatica), lime (Tilia cordata), and ash (Fraxinus excelsior) when they grow in mineral soil from an old fallow site with a pH of 6. We used an 15N‐labeling method to measure tree seedling 15N uptake in potted soils (Humic Cambisol) when both N forms NH$ _4^+ $ and NO$ _3^- $ were simultaneously present in the soil solution for interspecies comparison and assessment of relationships between specific 15N‐uptake rates and amino acid–accumulation rates or relative growth rates (RGR). The results demonstrate that tree species varied significantly in their capacity to take up NH$ _4^+ $ or NO$ _3^- $ into roots, stems, or leaves, but indicate only marginal differences in their preference for NH$ _4^+ $ or NO$ _3^- $ when they grow in mineral soil. The ranking of specific 15N‐uptake rates for NH$ _4^+ $ and NO$ _3^- $ was oak < beech < spruce < pine < lime < ash. Fine roots of all species had the highest specific 15N‐uptake rates for both N forms, followed by total roots, leaves/needles, and stems. As regards tree seedling species, we found negative relationships between glutamine (Gln)‐accumulation rates in leaves/needles and total 15N‐uptake rates in fine roots. Noteworthy was the fact that, at high Gln‐accumulation rates, the N‐uptake system in fine roots of ash was probably lower under feedback inhibition by the amino acid.

Nitrogen flux patterns through Oxisols and Ultisols in tropical forests of Cameroon, Central Africa

“…These values were within the range of previous reports (Eddy et al 2008;Uscola et al 2017), although the experimental conditions varied. Our results suggest that low fine root biomass but high specific N-uptake rate, which maximizes whole-plant growth rates (Osone and Tateno, 2005;Schulz et al 2011), would contribute to the suppression of N loss on Oxisols. In contrast, plants on Ultisols would invest more in root formation in the O horizon to capture N before leaching down to the mineral horizon.…”

Biological Flora of the British Isles:Fraxinus excelsior

“…). As fits with a nitrophilous species, Schulz, Härtling & Stange () found that the N uptake of 2‐year‐old seedlings was greatest in ash ( F. excelsior > Tilia cordata > Pinus sylvestris > Picea abies > Fagus sylvatica > Quercus petraea ) although relative growth rate in ash was similar to the other species (0.375 g fresh mass day −1 in ash). Ash can react well to fertilizers on poor soils (Bulíř ), but they have little effect on already rich soils (Culleton, Murphy & McLoughlin ).…”

A trait‐based ecosystem model suggests that long‐term responsiveness to rising atmospheric CO2 concentration is greater in slow‐growing than fast‐growing plants

“…N uptake is calculated on an annual time step as where k r (m 2 g −1 C) is a species trait that describes root N uptake efficiency (analogous to the light extinction coefficient). An increase in the value of k r increases the N uptake per unit root biomass (Zerihun & Bassirirad ; Schulze, Härtling & Stange ).…”