In this review, the unique features and facts of long-term experiments are presented. Long-term experimental plots provide information of forest stand dynamics which cannot be derived from forest ...inventories or small temporary plots. Most comprise unthinned plots which represent the site specific maximum stand density as an unambiguous reference. By measuring the remaining as well as the removed stand, the survey of long-term experiments provides the total production at a given site, which is most relevant for examining the relationship between site conditions and stand productivity on the one hand and between stand density and productivity on the other. Thus, long-term experiments can reveal the site-specific effect of thinning and species mixing on stand structure, production and carbon sequestration. If they cover an entire rotation or even the previous and following generation on a given site, they reveal a species’ long-term behaviour and any growth trends caused by environmental changes. Second, we exploit the unique data of European long-term experiments, some of which have been surveyed since 1848. We show the long-term effect of different density regimes on stand dynamics and an essential trade-off between total stand volume production and mean tree size. Long-term experiments reveal that tree species mixing can significantly increase stand density and productivity compared with monospecific stands. Thanks to surveys spanning decades or even a century, we can show the changing long-term-performance of different provenances and acceleration of stand production caused by environmental change, as well as better understand the growth dynamics of natural forests. Without long-term experiments forest science and practice would be not in a position to obtain such findings which are of the utmost relevance for science and practice. Third, we draw conclusions and show perspectives regarding the maintenance and further development of long-term experiments. It would require another 150 years to build up a comparable wealth of scientific information, practical knowledge, and teaching and training model examples. Although tempting, long-term experiments should not be sacrificed for cost-cutting measures. Given the global environmental change and the resulting challenges for sustainable management, the network of long-term experiments should rather be extended regarding experimental factors, recorded variables and inter- and transdisciplinary use for science and practice.
Key message
Centenary forest statistics informing major attributes of French forests were digitized, checked for consistency, and used to infer forest dynamics. Comparison to forest inventory data ...highlights increases in forest area and tree diversity, and substantial maturation of forests. Dataset access at
https://doi.org/10.5281/zenodo.3739458
Context
The history of European forest dynamic remains fragmental. In France, the
Daubrée
statistics (1908) and agricultural statistics (1892, 1929) formed fundamental material to fill this gap.
Aims
Release, test, and summarize the digitalized dataset. Analyze long-term forest changes in forest area, composition, and structure.
Methods
Primary data on forest area across NUTS-3 geographic units, split by forest management and ownership categories and dominating tree species (
Daubrée
), were digitized and cross-compared. Centennial changes in forest attributes were assessed from modern forest inventory data.
Results
Cross-comparison revealed: (1) strong temporal consistency in forest changes over time, (2) systematic and interpretable biases in ownership/management categories between
Daubrée
and agricultural statistics. Strong shift from coppices to high forests, increased prevalence of private ownership, and constant proportion of broadleaf- and conifer-dominated forests were highlighted, with increased tree species diversity at country scale.
Conclusion
Ancient statistics are shown to play a major role in retrospective land-use and forest policy analysis.
Abstract
Context
Bioenergy from wood can contribute to reach the goals of energy-transition policies. Use of wood as fuel should focus on low-quality wood, e.g. by-products from timber production, ...which production and supply is related to various management decisions. Reaching the policy objectives efficiently remains an issue.
Aims
The aims are (1) to develop a modelling approach that links local management decisions with indicators of the whole wood fuel production and supply chain and (2) to test the model in a case study. The study should further provide first insights on how indicators of energy, nutrient and worktime efficiency vary according to wood fuel chain characteristics and the related management decisions.
Methods
The model depicts the flow of wood (biomass, nutrients, moisture content, heating value) from the forest stand to the heating plant for each silvicultural intervention simulated with a growth and yield model. It further quantifies the energy and worktime spent on different wood fuel chain tasks (e.g. felling, forwarding) set by the user. We defined four scenarios according to the scale of energy production (large vs. small) and the demand for wood fuel (high vs. moderate).
Results
The case study revealed that the model outputs were plausible. Energy efficiency largely varied depending on the type of silvicultural intervention. Large-scale production associated with high demand was most favourable for energy and worktime efficiencies. In contrast, nutrient efficiency was best for small-scale production associated with moderate demand.
Conclusions
Local management decisions all along the wood fuel chain highly influenced efficiency indicators, and thus its relevance for energy-transition policies. Our model may contribute to strategic decision making in different forestry and energy production contexts.
Key message
We provide a database of 52 silvicultural scenarios recommended in French public forests including relevant dendrometric variables and metrics for carbon accounting. The dataset is ...available at
https://doi.org/10.57745/QARRFS
. Associated metadata are available at
https://metadata-afs.nancy.inra.fr/geonetwork/srv/fre/catalog.search#/metadata/f76ed27f-325d-493b-8731-0995dcaa7805
. Special attention was paid to offer carbon metrics required for the French
Label Bas Carbone
offset projects.
Key message
We present a methodological framework that both scientists and supply chain actors can mobilise to organise information at different scales of observation, and further make informed ...decisions regarding the supply and extraction of bio-molecules from forest biomass. We demonstrate its usefulness for extracting bio-molecules contained in silver fir growing in France.
Context
Numerous bio-active molecules can be extracted from trees at an industrial scale. Supply chain actors play a central role in this emerging bio-economy. However, they do not have enough information and tools to make informed decisions with respect to species, growing locations, or identities of potential suppliers of relevant wood biomass.
Aims
We explore and demonstrate an information chain and methodological framework that can help make three critical decisions regarding the selection of (1) the species containing the desired bio-molecules, (2) the locations where the resource is collected, and (3) the supply chain partners and types of industrial wood by-products necessary to obtain sufficient biomass for industrial extraction.
Methods
The methodological framework provides detailed guidelines and references to select the right combination of sampling protocol, allometric models, chemical analyses, GIS tools, and forest growth and supply chain models in order to produce information for the three decision steps within various regional contexts.
Results
We apply the framework within the context of supply chain actors who are interested in estimating the quantity and diversity of bio-molecules contained in silver fir (
Abies alba
Mill.) growing in the Grand Est region of France. We show how conflicting environmental, legal and economic constraints can affect the results. We discuss future challenges that need to be tackled to improve the methodological framework.
Conclusion
This study represents a highly detailed overview of the potential bio-molecules contained in a tree species, from its natural habitat or plantation to the end of the regional supply chain. It also represents a step towards the development of a generic knowledge infrastructure and methodology that is necessary to solve various decision-making problems regarding the industrial supply and extraction of high-value bio-molecules.
•We analysed nutrient (N, S, P, K, Ca, Mg, Mn) distribution patterns in roundwood.•A new, empirical-mechanistic modelling approach was applied to Fagus sylvatica.•Effects of roundwood diameter varied ...between nutrients and tissues (wood, bark).•A site-age effect was found, requiring additional data for further investigation.•Our generic modelling approach may be applied to other data and tree species.
Climate-mitigation strategies encourage the use of forest products and wood energy. This will likely increase the risk of soil depletion through nutrient exportation. Given the high variability in nutrient concentrations within and between trees, it is crucial to better understand the biochemical patterns of nutrient distribution and the related driving factors. Thus, predictions of nutrient concentrations can be improved, and used for assessing nutrient exportation through roundwood exploitation and for developing forest-management rules to maintain soil fertility. Our aims were to better determine (1) the shapes of the relationships between the total concentrations of different nutrients (N, S, P, K, Ca, Mg, Mn) in roundwood and roundwood diameter; (2) the variation of these relationships between different tissues (wood, bark); and (3) potential effects of site conditions and/or stand age on nutrient concentrations. We therefore developed a new modelling approach that relied on empirical and mechanistic relationships, and allowed for sound predictions of both concentrations in individual tissues and in total. We applied the approach to Fagus sylvatica using 134 trees from 11 plots that covered large ranges of ecological conditions in terms of geographic region (from the northwest to the northeast of France), site index (from <25m to >35m), stand age (form 10years to 159years), and roundwood diameter with nutrient concentrations being measured separately for wood and bark tissues partly up to a minimum diameter of 1cm. Relationships between total nutrient concentrations and roundwood diameter showed several different shapes: a reverse-J-shape for N, S and P; a U-shape for K; and no clear, more complex shapes for Ca, Mg and Mn. These shapes were related to concentration changes with roundwood diameter in both wood and bark for N, S and P (but with low goodness of fit for the models of N and S in the bark), while they were only related to concentration change in the wood for K, and in the bark for Ca and Mn (but with low goodness of fit for the model of Mn in the bark). Moreover, shifts of concentration-diameter curves (additive effect) were likely related to site conditions (chemical fertility), as assessed based on foliar nutrient concentrations. An additional effect of stand age could not be excluded, but so far it appeared difficult to clearly distinguish between influences of site and age. We argue that our modelling approach is particularly suitable to further tackle the issue of site and age effects, by combing data from several studies on the same species and/or on other species (genericness). Comprehensive forest-management rules based on silvicultural scenario simulation and assessment may finally be developed by coupling nutrient, biomass and site-sensitive tree-growth models.
L’épidémie de scolytes (essentiellement Ips typographus) qui sévit depuis 2018 dans les pessières d’Europe a conduit à une situation de crise dans la filière forêt-bois. Cette étude a pour objectif ...de caractériser et de comprendre la façon dont les acteurs font face à ces événements afin d’en tirer des enseignements pour de futures crises. Une enquête qualitative a été conduite entre novembre 2019 et janvier 2020 auprès de 41 acteurs de la filière forêt-bois dans les régions Grand Est, Bourgogne-Franche-Comté, Bade-Wurtemberg et Wallonie. Elle a mis en évidence des freins et points de blocage concernant la gestion de cette crise tels qu’un manque d’anticipation, des difficultés techniques et financières pour mener les actions opérationnelles nécessaires, une communication lente au niveau national, ou des difficultés administratives pour obtenir des aides financières. En revanche, la crise semble avoir conduit à un renforcement des collaborations au sein de la filière, notamment grâce au travail des structures interprofessionnelles.
La biomasse forestière peut être une source de molécules d’intérêt dans le but de substituer ou de compléter les molécules pétro-sourcées. Par conséquent, une valorisation innovante des extractibles ...du bois semble être une opportunité économique, sociale et environnementale. L’objectif de notre étude est de mieux cerner les perspectives d’émergence d’une nouvelle valorisation chimique des connexes bois pour la région Grand Est, à partir des avis et ressentis des acteurs de la filière forêt-bois et de la valorisation chimique de cette région ainsi que de territoires voisins. Nos résultats se portent sur trois axes : les stratégies de valorisation des connexes des entreprises de la filière forêt-bois, les perceptions des acteurs sur l’émergence d’une filière forêt-chimie, et les perspectives de mise en place d’une telle filière à moyen terme. Nous conviendrons tout de même que les résultats doivent être approfondis dans le cadre de perspectives de recherche pour préciser les conditions de la mise en œuvre de cette filière.
The objective of the study was to analyse to which extent horizontal crown plasticity reduces inter-tree competition at stand scale, and how it relates to species growth strategy. Two components of ...crown plasticity defined at the individual tree level (crown shape distortion, CSD and crown displacement relative to stem, CRD) were analysed and their relative importance in the reduction of competition was quantified. Inter-tree competition at stand scale was estimated using spatial pattern analysis and crown overlap estimation. Measurements were performed in a mixed broadleaved stand of Western Europe. Crown plasticity was shown to regularise the spatial distribution of crowns in comparison with the corresponding stems and to reduce inter-tree competition by optimising space occupation. A significant reduction in crown overlap was observed, mainly due to CRD and secondarily to CSD. At the species level, CSD and CRD were positively correlated. In addition, both were negatively correlated with species shade-tolerance scores. In particular, three European temperate tree species showed contrasting responses, which were related to their known specific ecological strategies.
Fagus sylvatica
, known to be a highly shade-tolerant species, showed large crowns, low CSD and CRD, indicating a low plasticity and suggesting a strong competitive ability. At the opposite,
Quercus
sp., known to be clearly less shade-tolerant, exhibited a reduced growth, associated with high CSD and CRD, indicating high crown plasticity and probably a lower competitive ability. For this species, plasticity could be described as passive. Last,
Carpinus betulus
, known to have a relatively good shade-tolerance, showed a contrasting behaviour with high CSD and CRD and a strong presence in the stand, suggesting high crown plasticity and a good competitive ability. In that case, plasticity was described as rather adaptive.
Models based on national forest inventory (NFI) data intend to project forests under management and policy scenarios. This study aimed at quantifying the influence of NFI sampling uncertainty on ...parameters and simulations of the demographic model MARGOT. Parameter variance–covariance structure was estimated from bootstrap sampling of NFI field plots. Parameter variances and distributions were further modeled to serve as a plug‐in option to any inventory‐based initial condition. Forty‐year time series of observed forest growing stock were compared with model simulations to balance model uncertainty and bias. Variance models showed high accuracies. The Gamma distribution best fitted the distributions of transition, mortality and felling rates, while the Gaussian distribution best fitted tree recruitment fluxes. Simulation uncertainty amounted to 12% of the model bias at the country scale. Parameter covariance structure increased simulation uncertainty by 5.5% in this 12%. This uncertainty appraisal allows targeting model bias as a modeling priority.
Recommendations for Resource Managers
•
Uncovering the potential and limitations of large‐scale forest models are needed when deducing recommendations from forest resource projections under forest management and policy scenarios at regional, national, or continental scales.
•
Estimating simulation uncertainty in these models is crucial to assess their accuracy. The present study offers a generic methodological strategy for assessing parameter uncertainty in large‐scale forest models.
•
Users of the MARGOT model should consider that simulation uncertainties proved to be low at a national scale, but decennial wood stock increases as observed in the French forests over the period 1970–2016 were underestimated.
•
Assessing simulation uncertainty is also major for model bias appraisal. Better accounting for the controls of forest demographic processes (growth, regeneration and mortality) appears to be a priority for the development of MARGOT, and for other large‐scale models.
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