Tree regeneration in models of forest dynamics – Suitability to assess climate change impacts on European forests

König, Louis A.; Mohren, Frits; Schelhaas, Mart-Jan; Bugmann, Harald; Nabuurs, Gert‐Jan

doi:10.1016/j.foreco.2022.120390

Cited by 26 publications

(29 citation statements)

References 117 publications

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“…However, the critical role of recruitment processes in determining forest composition has recently led to calls for explicit modeling of these processes (Hanbury-Brown et al, 2022;König et al, 2022;Kunstler et al, 2009;Price et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

Which demographic processes control competitive equilibria? Bayesian calibration of a size‐structured forest population model

Heiland

Künstler

Šebeň

et al. 2023

Ecology and Evolution

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In forest communities, light competition is a key process for community assembly. Species' differences in seedling and sapling tolerance to shade cast by overstory trees is thought to determine species composition at late-successional stages. Most forests are distant from these late-successional equilibria, impeding a formal evaluation of their potential species composition. To extrapolate competitive equilibria from shortterm data, we therefore introduce the JAB model, a parsimonious dynamic model with interacting size-structured populations, which focuses on sapling demography including the tolerance to overstory competition. We apply the JAB model to a two-"species" system from temperate European forests, that is, the shade-tolerant species Fagus sylvatica L. and the group of all other competing species. Using Bayesian calibration with prior information from external Slovakian national forest inventory (NFI) data, we fit the JAB model to short time series from the German NFI. We use the posterior estimates of demographic rates to extrapolate that F. sylvatica will be the predominant species in 94% of the competitive equilibria, despite only predominating in 24% of the initial states. We further simulate counterfactual equilibria with parameters switched between species to assess the role of different demographic processes for competitive equilibria. These simulations confirm the hypothesis that the higher shade tolerance of F. sylvatica saplings is key for its long-term predominance. Our results highlight the importance of demographic differences in early life stages for tree species assembly in forest communities.

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Section: Introductionmentioning

confidence: 99%

Which demographic processes control competitive equilibria? Bayesian calibration of a size‐structured forest population model

Heiland

Künstler

Šebeň

et al. 2023

Ecology and Evolution

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“…Unfortunately, we generally lack the information needed to fully understand the large‐scale drivers of tree regeneration. Tree regeneration is influenced by processes acting on multiple spatial and temporal scales (Hart et al, 2017; Levin, 1992), making it challenging to translate the mechanisms of small‐scaled subprocesses, competition, and climatic responses to larger scales where climatic variation becomes more visible because the stochasticity of small‐scaled processes averages out (König et al, 2022; Price et al, 2001; Ren et al, 2022). Trade‐offs between temporal and spatial coverage of tree regeneration data at larger scales (e.g.…”

Section: Introductionmentioning

confidence: 99%

Sheltered or suppressed? Tree regeneration in unmanaged European forests

Käber,

Bigler,

HilleRisLambers

et al. 2023

Journal of Ecology

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Tree regeneration is a key demographic process influencing long‐term forest dynamics. It is driven by climate, disturbances, biotic factors and their interactions. Thus, predictions of tree regeneration are challenging due to complex feedbacks along the wide climatic gradients covered by most tree species. The stress gradient hypothesis (SGH) provides a framework for assessing such feedbacks across species ranges, suggesting that competition between trees is more frequent under favourable conditions, whereas reduced competition (i.e. positive interactions) is more likely under climatic stress. Moreover, tree life‐history strategies (LHS) may shed light on how and whether the SGH explains regeneration of different tree species. To address these topics, we developed statistical models based on >50,000 recruitment events observed for 24 tree species in an extensive permanent plot network (6540 plots from 299 unmanaged European temperate, boreal and subalpine forests) covering a wide climatic gradient. We found that the effects of Leaf Area Index (as a proxy for competition) on tree recruitment changed along climatic gradients but in a species‐specific manner. Competition predominates, with its intensity decreasing under stressful conditions for most species, as predicted by the SGH. However, positive interactions were only evident for a few species. Additionally, the ability of the SGH to explain patterns of competition and positive interactions across the gradients differed among species, with some differences and exceptions that may be related to varying LHS. Synthesis. Our study shows that competition between trees toward climatic stress decreases systematically but depends on species stress tolerance to climate and shade. These findings explain within‐ and between‐species differences in tree recruitment patterns in European temperate forests. Moreover, our findings imply that projections of forest dynamics along wide climatic gradients and under climate change must accommodate both competition and positive interactions, as they strongly affect rates of community turnover.

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“…Although recruitment is known to be the result of a number of processes (flowering and pollination, fruit/seed production, dispersal, storage, seed predation, germination, seedling establishment and survival until the sapling stage), but they are challenging to include in models (Price et al, 2001;König et al, 2022). Recruitment in MEDFATE is hence modeled using a single aggregated process that estimates the appearance of young plants, as done in other models (Hanbury-Brown et al, 2022).…”

Section: Mortality and Recruitmentmentioning

confidence: 99%

“…Recruitment prediction could benefit from considering additional refinements, such as accounting for resprouting capacity or mechanistically dealing with seedling and sapling mortality (König et al, 2022), at the potential cost of increasing the number of non-observable model parameters.…”

Section: The Value Of Trait-enabled Models For the Projection Of Fore...mentioning

confidence: 99%

MEDFATE 2.8.1: A trait-enabled model to simulate Mediterranean forest function and dynamics at regional scales

Cáceres

Molowny‐Horas

Cabon

et al. 2022

Preprint

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Abstract. Regional-level applications of dynamic vegetation models are challenging because they need to accommodate the variation in plant functional diversity, which requires moving away from broadly-defined functional types. Different approaches have been adopted in the last years to incorporate a trait-based perspective into modeling exercises. A common parametrization strategy involves using trait data to represent functional variation between individuals while discard taxonomic identity, but this strategy ignores the phylogenetic signal of trait variation and cannot be employed when predictions for specific taxa are needed, as in applications to inform forest management planning. An alternative strategy involves adapting the taxonomic resolution of model entities to that of the data source employed for large-scale initialization and estimating functional parameters from available plant trait databases while adopting alternative solutions for missing data and non-observable parameters. Here we report the advantages and limitations of this second strategy according to our experience in the development of MEDFATE (v. 2.8.1), a novel cohort-based and trait-enabled model of forest dynamics, for its application over a region in the Western Mediterranean Basin. First, 217 taxonomic entities were defined according to woody species codes of the Spanish National Forest Inventory. While forest inventory data were used to obtain some empirical parameter estimates, a large proportion of physiological, morphological, and anatomical parameters were mapped to measured plant traits, with estimates extracted from multiple databases and averaged at the required taxonomic level. Estimates for non-observable key parameters were obtained using meta-modeling and calibration exercises. Missing values were filled using imputation procedures based on trait coordination, taxonomic averages or both. The model properly simulated observed historical basal area changes, with a performance similar to an empirical model trained for the same region. While strong efforts are still required to parameterize trait-enabled models for multiple taxa, estimation procedures can be progressively refined, transferred to other regions or models and iterated following data source changes by employing automated workflows. We advocate for the adoption of trait-enabled population-structured models for regional-level projections of forest function and dynamics.

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Tree regeneration in models of forest dynamics – Suitability to assess climate change impacts on European forests

Cited by 26 publications

References 117 publications

Which demographic processes control competitive equilibria? Bayesian calibration of a size‐structured forest population model

Which demographic processes control competitive equilibria? Bayesian calibration of a size‐structured forest population model

Sheltered or suppressed? Tree regeneration in unmanaged European forests

MEDFATE 2.8.1: A trait-enabled model to simulate Mediterranean forest function and dynamics at regional scales

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