Dr. Christoph Fischer

The dataset includes Pan-European maps of timber volume (Vol), above-ground biomass (AGB), and deciduous-coniferous proportion (DCP) with a pixel size of 10×10 m for the reference year 2020. In addition, a measure of prediction uncertainty is provided for each pixel. The maps have been created using a combination of a Sentinel-2 mosaic, Copernicus layers, and National Forest Inventory (NFI) data.
The mapping was done with the k-Nearest Neighbour (kNN, k=7) approach with harmonized data of species-specific Vol and AGB from 14 NFIs consisting of approximately 151 000 field plots across Europe. The maps cover 40 European countries, forming a continuous coverage of the western part of the European continent.
A sample of 1/3 of NFI plots was left out for validation, whereas 2/3 of the plots were used for mapping. Maps were created independently for 13 multi-country processing areas. Root-mean-squared-errors (RMSEs) for AGB ranged from 53 % in the Nordic processing area to 73 % in the South-Eastern area. The maps are on average nearly unbiased on European level (1.0 % of the mean AGB), but show significant overestimation for small biomass values (53 % bias for forests with AGB less than 150 t/ha) and underestimation for high biomass values (-55 % bias for forests with AGB higher than 500 t/ha).
The created maps are the first of their kind as they are utilizing a large number of harmonized NFI plot observations and consistent remote sensing data for high-resolution forest attribute mapping. While the published maps can be useful for visualization and other purposes, they are primarily meant as auxiliary information in model-assisted estimation where model-related biases can be mitigated, and field-based estimates improved. Therefore, additional calibration procedures were not applied, and especially high Vol and AGB values tend to be underestimated. We therefore discourage from summarizing map values (pixel counting) over areas in interest, as this may inadvertently result in biased estimates.

The size of a tree and its crown are key drivers of its ability to intercept light. These characteristics are also constrained by biomechanical and hydraulic limitations, leading to tremendous variations in crown size and tree height between species. To date, there is no consensus on how covariation between crown characteristics (i.e. tree height, crown diameter and relative crown depth) control the spectrum of crown sizes, nor on the species characteristics (i.e. species climate niche or functional traits) that govern their variation. Using species-specific allometric relationships accounting for local competition data on individual crown characteristics of tree species across Europe and North America, we showed that the spectrum of tree crown size is mainly driven by two independent axes: one correlating tree height with relative crown depth, and another linking crown diameter to crown volume. While both angiosperms and gymnosperms exhibited similar patterns of covariation for these crown characteristics, distinct ecological strategies emerged for maximum tree height. We also highlighted that shade-tolerant species were characterized by wider and deeper crowns and showed reduced sensitivity to local competition in relative crown depth, indicating enhanced competitive resilience. Finally, simulations of light interception in virtual stands performed using a ray tracing algorithm highlighted the importance of different crown characteristics in various competitive contexts. Tree height was the primary determinant of light interception in low competitive contexts, common in early successional stages, whereas relative crown depth and crown diameter played a more significant role in high-competitive contexts typical of late succession. These findings suggest that shade-tolerant species, with their deeper crowns, are better equipped to intercept light under competition and ultimately emphasize the ability of shade tolerance to improve the realism of forest dynamic models as it can be used as an indicator of crown size and its response to competition.

The Forest Report 2025 is the third publication of its kind, with previous versions appearing in 2005 and 2015. It is aimed at experts and anyone interested in forest and wood-related issues. The report provides an overview of the condition and development of Swiss forests over the past ten years and assesses the outlook for all relevant areas against the backdrop of advancing climate change. With a structure modelled on Forest Europe reports, the Forest Report sets out internationally comparable results and serves as a benchmark publication. It uses a broad range of data from long-term surveys to answer important questions for society, economic players and policymakers.

Der Waldbericht erscheint 2025 zum dritten Mal nach 2005 und 2015. Er richtet sich an Fachleute und an eine am Thema Wald und Holz interessierte Leserschaft. Der Waldbericht ist eine Gesamtschau über Zustand und Entwicklungen des Schweizer Waldes in den letzten zehn Jahren und gibt einen Ausblick für alle Themenbereiche im Hinblick auf den fortschreitenden Klimawandel. Mit seiner an den Berichten von Forest Europe orientierten Struktur liefert der Waldbericht international vergleichbare Ergebnisse und dient als Referenzpublikation. Er beantwortet anhand einer breiten Datenbasis aus Langzeiterhebungen wichtige Fragen für Gesellschaft, Wirtschaft und Politik.

Après 2005 et 2015, le Rapport forestier paraît pour la troisième fois, en 2025. S'adressant aux spécialistes et aux lecteurs intéressés par le thème de la forêt et du bois, il offre un aperçu général de l'état et de l'évolution de la forêt suisse au cours des dix dernières années, et propose pour chaque chapitre thématique un regard vers l'avenir tenant compte des changements climatiques. Structuré de façon similaire aux rapports de Forest Europe, il fournit des informations reproductibles au niveau international et fait figure de publication de référence. Le Rapport forestier répond à des questions importantes pour la société, l'économie et la politique en se fondant sur une vaste base de données issues d’enquêtes à long terme.

The Forest Report 2025 is the third publication of its kind, with previous versions appearing in 2005 and 2015. It is aimed at experts and anyone interested in forest and wood-related issues. The report provides an overview of the condition and development of Swiss forests over the past ten years and assesses the outlook for all relevant areas against the backdrop of advancing climate change. With a structure modelled on Forest Europe reports, the Forest Report sets out internationally comparable results and serves as a benchmark publication. It uses a broad range of data from long-term surveys to answer important questions for society, economic players and policymakers.

Nel 2025 il Rapporto forestale giunge alla sua terza edizione dopo quelle del 2005 e 2015. Destinato ad esperti e lettori interessati al tema del bosco e del legno, il rapporto fornisce uno spaccato generale su stato ed evoluzione del bosco svizzero negli ultimi dieci anni e traccia una prospettiva per tutte le aree tematiche tenendo conto del cambiamento climatico in corso. Essendo strutturato come quelli di Forest Europe, il rapporto mette a disposizione risultati comparabili a livello internazionale e serve come pubblicazione di riferimento. Mediante una vasta base di dati provenienti da rilevamenti di lungo periodo, risponde a interrogativi importanti per la società, l'economia e la politica.

The Forest Report 2025 is the third publication of its kind, with previous versions appearing in 2005 and 2015. It is aimed at experts and anyone interested in forest and wood-related issues. The report provides an overview of the condition and development of Swiss forests over the past ten years and assesses the outlook for all relevant areas against the backdrop of advancing climate change. With a structure modelled on Forest Europe reports, the Forest Report sets out internationally comparable results and serves as a benchmark publication. It uses a broad range of data from long-term surveys to answer important questions for society, economic players and policymakers.

Der Waldbericht erscheint 2025 zum dritten Mal nach 2005 und 2015. Er richtet sich an Fachleute und an eine am Thema Wald und Holz interessierte Leserschaft. Der Wald­bericht ist eine Gesamtschau über Zustand und Entwicklungen des Schweizer Waldes in den letzten zehn Jahren und gibt einen Ausblick für alle Themenbereiche im Hinblick auf den fortschreitenden Klimawandel. Mit seiner an den Berichten von Forest Europe orientierten Struktur liefert der Waldbericht international vergleichbare Ergebnisse und dient als Referenzpublikation. Er beantwortet anhand einer breiten Datenbasis aus Langzeiterhebungen wichtige Fragen für Gesellschaft, Wirtschaft und Politik.

The Forest Report 2025 is the third publication of its kind, with previous versions appearing in 2005 and 2015. It is aimed at experts and anyone interested in forest and wood-related issues. The report provides an overview of the condition and development of Swiss forests over the past ten years and assesses the outlook for all relevant areas against the backdrop of advancing climate change. With a structure modelled on Forest Europe reports, the Forest Report sets out internationally comparable results and serves as a benchmark publication. It uses a broad range of data from long-term surveys to answer important questions for society, economic players and policymakers.

Forest biomass is an essential resource in relation to the green transition and its assessment is key for the sustainable management of forest resources. Here, we present a forest biomass dataset for Europe based on the best available inventory and satellite data, with a higher level of harmonisation and spatial resolution than other existing data. This database provides statistics and maps of the forest area, biomass stock and their share available for wood supply in the year 2020, and statistics on gross and net volume increment in 2010–2020, for 38 European countries. The statistics of most countries are available at a sub-national scale and are derived from National Forest Inventory data, harmonised using common reference definitions and estimation methodology, and updated to a common year using a modelling approach. For those counties without harmonised statistics, data were derived from the State of Europe's Forest 2020 Report at the national scale. The maps are coherent with the statistics and depict the spatial distribution of the forest variables at 100 m resolution.

Forests are under pressure and going through rapid changes. However, current inventorying and monitoring (IM) programs are often either disjointed, too narrow in their scope and/or do not operate at fine enough temporal resolutions, which may hinder scientific understanding, the timely supply of information, fast decision making, and may result in the sub-optimal use of resources. For these reasons, there is an urgent need for Advanced Forest Inventorying and Monitoring (AIM) programs to (i) achieve expanded relevance (by augmenting data/information across ecosystem properties and trophic levels), (ii) have increased temporal resolution (by tailored data collection frequency), and (iii) make use of technological advances (by incorporating novel tools and technologies). The Advanced Inventorying and Monitoring for Swiss Forests (SwissAIM) initiative was launched in 2020 to address these needs. SwissAIM builds upon the foundation offered by the existing programs (e.g., national forest inventory, long-term forest ecosystem research, biodiversity monitoring). It aims to offer a collaborative and adaptive framework to enable integrated data collection, evaluation, interpretation, analysis, and modeling. Ideally, it will result in a more responsive system with respect to current and predicted biotic/abiotic stressors that will challenge Swiss forests. Developing such a system implies identifying the information needs of different stakeholders (e.g., science, policy, practice), related technical requirements, and governance frameworks. Here, we present (i) the main features of the SwissAIM initiative (vision, scientific questions and variables, governance and engagement), (ii) the main outcomes of the participatory design process (measurements, sampling, and plot design), (iii) the potential transferability of AIM initiatives outside Switzerland (timing, relevance, practicability), and (iv) the key messages that emerged (i.e., need for advancement, integration and transdisciplinarity, statistical underpinning). Since similar needs related to forest inventorying and monitoring are emerging throughout Europe and elsewhere, the objective of this opinion paper is to share our experience and promote a dialog with those interested in developing AIM initiatives in other countries and regions.

Consistent knowledge about the increment in European forests gained amplified importance in European policies and decision processes related to forest-based bioeconomy, carbon sequestration, sustainable forest management and environmental changes. Until now, large-area increment information from European countries was lacking international comparability. In this study we present a harmonisation framework in accordance with the principles and the approach established for the harmonisation of National Forest Inventories (NFIs) in Europe. 11 European NFIs, representing a broad range of increment measurement and estimation methods, developed unified reference definitions and methods that were subsequently implemented to provide harmonised increment estimates by NUTS regions (Nomenclature of territorial units for statistics of the European Union), main forest types and tree species groups, and to rate the impact of harmonisation measures. The main emphasis was on gross annual increment (GAI), however, also annual natural losses (ANL) and net annual increment (NAI) were estimated. The data from the latest available NFI cycles were processed. The participating countries represent a forest area of about 130 million ha, and 82% of the European Unions’ (EU) forest area, respectively. The increments were estimated in terms of volume (m³ year⁻¹, m³ ha⁻¹ year⁻¹) and above-ground biomass (t year⁻¹, t ha⁻¹ year⁻¹). The harmonised GAI volume estimates deviate in a range of +12.3% to −26.5% from the estimates according to the national definitions and estimation methods. Within the study area, the harmonised estimates show a considerable range over the NUTS regions for GAI, from 0.6 to 12.3 m³ ha⁻¹ year⁻¹, and 0.8–6.4 t ha⁻¹ year⁻¹, of volume and above-ground biomass, respectively. The largest increment estimates are found in Central Europe and gradually decrease towards the North, South, West and East. In most countries coniferous forests show larger increment estimates per hectare than broadleaved forests while mixed forests are at an intermediate level. However, in some instances, the differences were small or mixed forests revealed the largest increment estimates. The most important tree species groups in the study area are Pinus spp. and Picea spp., contributing 29% and 26% of the estimated total GAI volume, respectively. The shares of the prevalent broadleaved species are smaller with contributions of 9%, 7% and 6% by Quercus spp., Fagus sylvatica and Betula spp. The results underline the importance of harmonisation in international forest statistics. Looking ahead, harmonised large-area increment estimation is pivotal for accurate monitoring and evidence-based policy decisions in the changing context of future forest ecosystems dynamics, management strategies and wood availability.

Understanding and monitoring the surrounding environment increasingly rely on its 3D representations. However, the often high costs of 3D data equipment limit its wide usage, and low-cost solutions are in demand. Here, we propose a novel approach based on spherical stereo videos captured with a known baseline (distance between the cameras) for a low-cost and efficient 3D point cloud reconstruction. In a forest environment, we evaluated 1) the influence of baseline length on point cloud quality and 2) the suitability of the generated point clouds for extracting primary forest attributes (tree position and diameter). Our results show that the proposed approach allows for feasible 3D reconstruction of complex forest plots. The highest point cloud quality was achieved with a baseline of 60 cm. This setup enabled the correct detection of more than 65% of the trees within the forest plots, producing an average tree position error between 30 and 50 cm and clearly outperforming other setups. A Multiscale Model-to-Model Cloud (M3C2) analysis showed signed distances between the generated point cloud and the reference data with zero mean and 1 m standard deviation. We demonstrate that the proposed approach can be a valuable low-cost solution for 3D point cloud reconstruction, facilitating forest assessment and monitoring.

Die Wetterextreme der letzten Jahre haben im Schweizer Wald deutliche Spuren hinterlassen. Es gibt mehr geschädigte und tote Bäume. Ausserdem wachsen weniger junge Bäume nach. Dies zeigen die Zwischenresultate über die Erhebungsjahre 2018 bis 2022 des laufenden fünften Landesforstinventars (LFI5), die am 30. Mai 2023 veröffentlicht worden sind. Die Eidgenössische Forschungsanstalt für Wald, Schnee und Landschaft (WSL) und das Bundesamt für Umwelt (BAFU) führen das Inventar gemeinsam durch.