Contrasting Resource Dynamics in Mast Years for European Beech and Oak—A Continental Scale Analysis

Abstract

Resource allocation to different plant tissues is likely to be affected by high investment into fruit production during mast years. However, there is a large knowledge gap concerning species-specific differences in resource dynamics. We investigated the influence of mast years on stem growth, leaf production, and leaf carbon (C), nitrogen (N), and phosphorus (P) concentrations and contents in Fagus sylvatica, Quercus petraea, and Q. robur at continental and climate region scales using long-term data from the International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests) and similar datasets. We discussed the results in the light of opposing resource dynamics hypotheses: (i) resource accumulation before mast years and exhaustion after mast years (resource storage hypothesis), (ii) shifting resources from vegetative to generative compartments (resource switching hypothesis), and (iii) investing resources concurrently in both vegetative and generative compartments (resource matching hypothesis). Linear mixed-effects modelling (LMM) showed that both stem growth and leaf production were negatively influenced by weather conditions which simultaneously lead to high fruit production. Thus, the impact of generative on vegetative growth is intermixed with effects of environmental factors. Superposed epoch analyses and LMM showed that for mast behaviour in F. sylvatica, there are indicators supporting the resource storage and the resource switching hypotheses. Before mast years, resources were accumulated, while during mast years resources switched from vegetative to generative tissues with reduced stem and leaf growth. For the Quercus species, stem growth was reduced after mast years, which supports the resource storage hypothesis. LMM showed that leaf C concentrations did not change with increasing fruit production in neither species. Leaf N and P concentrations increased in F. sylvatica, but not in Quercus species. Leaf N and P contents decreased with increasing fruit production in all species, as did leaf C content in F. sylvatica. Overall, our findings suggest different resource dynamics strategies in F. sylvatica and Quercus species, which might lead to differences in their adaptive capacity to a changing climate.

Variation in Leaf Morphological Traits of European Beech and Norway Spruce Over Two Decades in Switzerland

“…Beech DM100 and LA both increased with autumn temperatures of the preceding year. This is in line with the study of Nussbaumer et al (2021), who found that high temperatures in September and October of the preceding year influenced the annual leaf production of beech. Nussbaumer et al (2021) used the total leaf mass in litterfall in their model, and therefore they could not determine whether enhanced leaf biomass resulted from the production of more leaves or from an increase in dry mass of individual leaves.…”

“…It should be noted that many of the leaf samples in 2019 were damaged and had perforation holes, which might also skew our findings toward a higher LMA. The effects of the summer and autumn climate (i.e., VPD, T) in the preceding year confirm the existence of legacy effects on leaf primordia buds that influence the development of beech leaves in the current year (e.g., Nussbaumer et al, 2021). The reason for the negative effect of winter temperatures on LMA in our temporal analysis remains uncertain, but might be related to temperature-driven shifts in the timing of leaf phenology (Clark et al, 2014).…”

“…However, due to the lack of high-resolution data on seeding intensity for spruce, it remains unclear whether this was driven by mast-year effects or by the particularly hot and dry spring, which was also reported by Swidrak et al (2013). The negative effects of mast years on beech LMTs and potentially on spruce LMTs may be explained by tradeoffs in resource allocation during high fructification (Nussbaumer et al, 2021), which lead to reduced leaf and radial growth.…”

“…Therefore, climatic conditions in both the preceding year (bud formation) and the year in which the leaves flush and grow (bud expansion) can potentially influence leaf morphology, in particular leaf size (Roloff, 1987;Coder and Warnell, 1999). Similarly, the occurrence of mast years is determined by the climatic conditions of the preceding summer (Müller-Haubold et al, 2015;Nussbaumer et al, 2021) and has been shown to influence leaf size and mass, with smaller leaves or lower dry mass observed in years with high fructification.…”

MASTREE+: Time‐series of plant reproductive effort from six continents

“…understand how variable allocation to reproduction influences carbon sequestration above and belowground, and how this varies between species and across environmental gradients(Bajocco et al, 2021;Nussbaumer et al, 2021;Oddou-Muratorio et al, 2021;Zhang et al, 2022). Related work can use MASTREE+ data combined with F I G U R E 3 Distribution of time-series in MASTREE+ according to local climate (Worldclim v2.1, 30 arcsecond resolution,Mosier et al, 2014).…”