the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 22 Apr 2026
A multi-nutrient budget helps to understand masting regulation in beech forests along a fertility gradient
Abstract. Forest ecosystem fertility and tree nutrition strongly depend on efficient biogeochemical nutrient cycles. Mast events require large amounts of carbon and nutrients and may therefore affect cycling efficiency. This study aimed to quantify the impact of episodic mast events on multiple nutrient fluxes under contrasting fertility conditions.
We conducted a multi-nutrient study (K, Mg, P, S and N) over an 12-year period (2012–2023) in three mature European beech (Fagus sylvatica L.) forests along a fertility gradient (S1>S2>S3). Nutrient fluxes associated with aboveground biomass production (wood, leaves and reproductive organs), canopy leaching, and leaf nutrient resorption were quantified. Mast effects were assessed by comparing mast years (MY) and non-mast years (NMY).
Across ecosystems, total aboveground biomass production increased by 19% on average during MY due to reproductive organ formation, while wood and leaf production remained unchanged. MY significantly enhanced nutrient fluxes via litterfall but also via canopy leaching particularly for K (+46%, +9 kg ha⁻¹ yr⁻¹), with impacts on seasonal dynamics. In contrast, leaf nutrient resorption was globally not affected by MY. The total nutrient content in aboveground biomass production (NCB ; sum of all the measured fluxes) increased for all nutrients during MY compared to NMY, with the strongest responses observed for Mg (+53%), K (+44%) and P (+43%), and more moderate effects for S (+24%) and N (+9%). Overall, our results highlight that canopy leaching and resorption, which remain understudied, are essential for accurately estimating nutrient budgets in aboveground biomass production.
A clear fertility effect was observed, with higher fruit production and increasing K, Mg and P requirements from S3 to S1. Despite elevated nutrient demands, MY did not induce nutrient limitation or reduce vegetative growth, indicating that current soil and tree nutrient reserves accross the 3 ecosystems are sufficient to buffer reproductive costs under present climatic conditions. This study highlights the importance of a multi-nutrient perspective and proposes a novel indicator comparing MY nutrient budgets with available nutrient reserves to better assess nutritional constraints associated with masting.
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Status: final response (author comments only)
- RC1: 'Comment on egusphere-2026-2053', Anonymous Referee #1, 27 Jun 2026
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RC2: 'Comment on egusphere-2026-2053', Anonymous Referee #2, 10 Jul 2026
In this contribution, Touche et al. investigate the annual nutrient budget of trees (Fagus sylvatica) in mast vs. non-mast years (MY vs NMY), along a soil fertility gradient. The main results is that MY are characterised by higher mobilization of nutrients, with higher return of nutrients to litter, with no impact on the production of wood or leaves.
This multi-nutrient (N, P, K, S, Mg) study brings a lot to the currently very active research field around forest fruit production and regeneration. Notably because it sheds light on still obscure aspects of tree nutrition on one of the most studied tree genera (Fagus) in these questions of fruit production (a wealth of research from English (e.g. Hacket-Pain et al.), Polish (Bogziewicz et al.), Spanish (Fernandez-Martinez et al.), Japanese (Han et al.) teams ; most of them (European ones, on Fagus sylvatica) dealing about trade-offs between growth and reproduction, others (Japanese ones, on Fagus crenata) dealing with the influence of nitrogen on flower initiation and fruit production).
The presentation of results is simple and clear.
The methods however need clarification:
- one important aspect that is not discussed at all and possibly overlooked in the resorption of nutrient along wood maturation / heartwood formation.
The authors explain that wood growth was assessed from girth increment (L163-165) and allometric equations (L249-256) and that the nutrient flux associated was computed by multiplying wood growth with tissue nutrient contents determined previously (Calvaruso et al. 2017 ; in the latter paper, no details are given regarding which wood depth was considered for determining tree nutrient contents).
Hence the current manuscript overlooks the fact that nutrient content decreases along the radial profile (see e.g. Penninckx et al. 2001), a pattern which probably relates to nutrient remobilization during wood ageing, even in Beech. This point, and the fact that the authors do not consider the wood remoblization flux, need clarification and clear argumentation.- another point is related to the computation of NCB (i.e. the "nutrient content of aboveground biomass"). It's unclear to me and to my opinion misleading that NCB (nutrient amount required for biomass production) includes the resorption flux. I do agree this includes the canopy exchanges when positive (because this flux is lost by the aerial organs but has been part of them). In fact what would need to be measured is canopy green leaves content. Since the authors do not have this, they use a surrogate (= litterfall + resorption flux, which is about equal to green leaf content).... this is not easy to understand and must be clearly justified.
The overall production levels reported e.g. in Figure 2 are high to very high for temperate forests, but still plausible.
One central result is that during MY no trade-off is observed between fruit and wood production, even in the less fertile plot, which is different from what had been reported mostly in synthesis studies (Lebourgeois et al. 2018, Hacket-Pain et al. 2017) as ackwnowledged by the authors. What would be interesting here is to compare the nutritional and water status of trees at Montiers and on the sites considered in these studies, in order to evaluate whether this different behaviour is related to overall "better" nutritional and water status of Montiers plots.
Overall, this is a very interesting manuscript, with clarifications to be done before publication.
Specific comments:
L13: replace "an" by "a"
L43: Biological nitrogen fixation also contributes to N inputs. Please mention here.
Figure 1: nice plot. "Mineral weathering" does not apply to N, mention this in the figure caption. "Biological nitrogen fixation" applies to N, mention this also in the figure caption.
L54: I suggest replacing "exchanges and relationships" by "fluxes", if the authors agree.
L58-59: replace "individuals of the same species and the same stand" by "individuals of the same population"
L90: "Considering literature" is vague. Detail how the reference to literature led you to these specific hypotheses.
L106: there is an extra space in the web address
L150-151: precise "microbial processing of the organic matter"
L155: sampling leaves for nurtient content "in August" is imprecise, and possibly misleading. Which date exactly were condisered: the beginning of the month? the end of the month?. August is also relatively late to get fully mature leaves. Resorption has probably already started in August (e.g. Montpied et al. 2009), and this may particularly be the case in dry years.
L161: replace "before the grounding process" by "before being grinded"?
L164: was circumference meausrement done at invariant position on the stem. State it.
L191: "in March of subsequent year": so there was absolutely no sapling between march and august ? (some, even if little material fall in between for sure).
Equation 2: isn't dry deposition (DD) a part of bulk deposition (BD)? Please clarify.
Equation 3: how were SD_na and BD_na measured? (as well as SD and BD for the other nutrients)
L219: "obtained"
L225-247: this section is unclear because the definition of CE_sv1 and CE_sv2 is unclear. Clarify.
L228: replace "modelize" by "model" or "simulate"
Equation 7: what do CE_SV1 (or CE_SV2) mean?
L262: "is quantified"
Table 2: what does "ecosystem" refer to here?
Table 2: "1|replicate": indicate this for each line of the table. Confuse
L286: replace "applied" by "mentioned"
L290-291: Where do we see this (which figure)? Need to display the actual time series (e.g. as a suppl mat)!
L334: "Mellert"
"Year after MY... time series not considered"
Figure 6: replace the qualitative "sampling period" by a quantitative time indicator, in order to place the value in the season.
L381: "0< foliar leaching ; 0> foliar absorption" --> this is the opposite, right?
L388: repetition of "during MY"
L440: replace "thereby explaining" by "probably causing"
L446-447: But do we see this anywhere ? No. Illustrate or mention as an hypothesis.
L455: "a process that may be negatively affected by the fruit biomass during MY". Interesting but unclear, clarify.
L455: why is "in the soil" crossed?
L485: probably because resorption fluxes are little affected and the fruit litter decomposes fast so that the nutrients are recycled rapidly and available as soon as the year after msting? Have you specifically looked at years after masting ? This would be interesting.
And highlight again the fact we need to see the time series as a suppl mat (at least)! (see comment above).Figure 9: about the figure design: I would put leaf_resorption and leaf_s close together because they are part of what would be the "green leaf content" that we would like to have.
L506-507: "significant differences among ecosystems": is it in terms of wood production or fruit production?
Table 3: what do numbers between brackets represent?
L521: "reduced"
L550: what does "available" mean: is it "available to plants"? Precise it.
L553: parentheses missing: "(soil reserve + resorption)"
L563: rephrase to "Given that many worldwide forest ecosystems experience low P or K availability"
L574 "This pattern can be attributed to Montiers": rephrase to: "this pattern may be particular to our study site, where..."
L575: remove "C" --> "allocation" instead of "C allocation"
L578: "which increased by 46% (+9 kg.ha-1.yr-1) in MY" (add "in MY").
L585: rephrase to "In MY, a substantial..."
References cited:
Montpied, P., Granier, A., & Dreyer, E. (2009). Seasonal time-course of gradients of photosynthetic capacity and mesophyll conductance to CO2 across a beech (Fagus sylvatica L.) canopy. Journal of experimental Botany, 60(8), 2407-2418.
Penninckx, V., Glineur, S., Gruber, W., Herbauts, J., & Meerts, P. (2001). Radial variations in wood mineral element concentrations: a comparison of beech and pedunculate oak from the Belgian Ardennes. Annals of Forest Science, 58(3), 253-260.
Citation: https://doi.org/10.5194/egusphere-2026-2053-RC2 - EC1: 'Comment on egusphere-2026-2053', Erika Buscardo, 14 Jul 2026
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- 1
This manuscript investigates how mast events affect nutrient cycling by quantifying changes in nutrient pathways and total nutrient content in aboveground biomass. The study site is a mature beech forest in northeastern France, part of an existing long-term observatory, with data spanning 2012–2023 across four mast years and eight non-mast years. The introduction is well written and clearly states the motivation of the study, with well-defined objectives. The materials and methods are similarly clear, though a few additions would improve reproducibility, including citations for data sources and the R packages used. I would also suggest the authors use a term other than "ecosystems" when referring to the experimental sites, as this risks creating confusion about the nature of the study locations, particularly since the main distinction between plots is soil fertility. Soil fertility is certainly an important driver of ecosystem differentiation, but since no other distinguishing factors are discussed, the term risks overstating the contrast between sites.
The Results section would benefit from a few changes to help readers follow the main takeaways. First, the opening paragraph should define the half-mast year more explicitly, given how heavily the term is used throughout this section. Second, the figures would benefit from panel labeling and more consistent in-text callouts. Third, the Figure 6 caption needs revision, as it is currently difficult to understand how the data were binned and the objectives and takeaways from it. Also, please consider adding an indicator of the different seasons to the graph to help the reader more easily understand the data.
The Discussion does a good job relating the main results to existing literature. That said, I would like to better understand why soils were not directly sampled in this study, particularly since the authors themselves note that such coupled research remains scarce, and the analysis relies heavily on the fertility gradient between sites. More detail on soil nutrient stores would strengthen the manuscript, especially given some apparent inconsistencies in Table 1. For example, site S3, described in the manuscript as the least fertile, shows comparatively high organic matter content, particularly at the surface, relative to the other sites. The manuscript attributes S3's lower fertility to reduced nutrient and water reserves, but S3 is also the shallowest soil, which could be just as influential in driving the greater production observed during mast years. This is not a fatal flaw in the study design, but the authors should clarify how the fertility gradient was characterized. For instance, whether fertility is based on organic matter content, base saturation, or another metric/metrics. Making this explicit would also strengthen the discussion of study limitations and future research directions.
Overall, once these minor issues are addressed, I believe this manuscript will be a valuable contribution to the literature and recommend it for acceptance. I list some technical corrections below that should be addressed before publication.