Abstract
Decreasing phosphorus (P) concentrations in leaves of beech (Fagus sylvatica L.) across Europe raise the question about the implications for forest health. Considering the distribution of beech forests on soils encompassing a broad range of nutrient availability, we hypothesized that this tree species exhibits high phenotypic plasticity allowing it to alter mass, and nutrient allocation in response to local nutrient availability. To test this, we grew two groups of 12–15 year old beech saplings originating from sites with high and low soil P availability for 2 years in mineral soil from their own site and in soil from the other site. After two growing seasons, P concentrations in leaves and stem, as well as mass allocation to leaves and fine roots were affected by both soil and plant origin. By contrast, relative P allocation to leaves and fine roots, as well as P concentrations in fine roots, were determined almost entirely by the experimental soil. Independent of the P nutritional status defined as average concentration of P in the whole plant, which still clearly reflected the soil conditions at the site of plant origin, relative P allocation to leaves was a particularly good indicator of P availability in the experimental soil. Furthermore, a high plasticity of this plant trait was indicated by a large difference between plants growing in the two experimental soils. This suggests a strong ability of beech to alter resource allocation in response to specific soil conditions.
Highlights
Forests dominated by beech (Fagus sylvatica L.) cover a large part of Europe from southern Norway to southern Italy and from northern Spain to northwest Turkey (Brunet et al, 2010; Durrant et al, 2016)
Plant parts not used for the analyses described above, were oven dried at 60◦C for 48 h or 72 h, weighed, and ground to fine powder using a ball mill
During the first growing season, both total and metabolic P concentrations in leaves were slightly higher for beech saplings originating from BBR, the site with high soil P availability, than for those from LUE, the site with low soil P availability (Table 2)
Summary
Forests dominated by beech (Fagus sylvatica L.) cover a large part of Europe (ca 14–15 Mha) from southern Norway to southern Italy and from northern Spain to northwest Turkey (Brunet et al, 2010; Durrant et al, 2016). Analysis of data from forest monitoring plots (ICP forest level II) across Europe between 1991 and 2010 revealed a significant decline in P concentrations and an increase of N/P ratios in beech leaves on the majority of plots (Jonard et al, 2015; Talkner et al, 2015) confirming findings of earlier regional studies (Flückiger and Braun, 1998; Duquesnay et al, 2000; Jonard et al, 2009; Braun et al, 2010) These changes in leaf nutrient status have been attributed to continuing. One reason for the conflicting results could be that often only total P concentrations in soil are available which not sufficiently reflect this elements bioavailability Another explanation could be the strong seasonal and site dependent variability of P concentrations in plant tissues (Yang et al, 2016; Netzer et al, 2017; Zavišicand Polle, 2018). This points to the importance of seasonal dynamics of nutrient uptake and plant internal nutrient allocation
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