Forest Regeneration Network WSL

Forest regeneration is a central process in the dynamic of forests. The process concerns the re-establishment or regrowth of trees and predominantly intensifies in pulses after natural or anthropogenically induced disturbances. Its key role in the resilience of forests to environmental change translates to the forest’s adaptation to climate change: by changes in species composition and forest structure. Regeneration includes all phases from flower primordia differentiation, seed production, seed dispersal, seed germination, seedling establishment and ingrowth to tree layer. It addresses both types natural and artificial reproduction considering genetic variation and phenotypic plasticity.

Currently, research on tree regeneration is conducted by seven research units located in Birmensdorf, Davos and Cadenazzo. Third party money is acquired by many research groups on various topics related to forest regeneration. From 2012 to 2021, a total of 195 publications appeared on this subject, 150 of which in peer-reviewed journals or books. In 2022, an internal concept paper (Brang et al.) outlined the leading role of WSL in forest regeneration research at both national and international scale. To better coordinate diverse internal activities such optimizing the use of methods, assessment technics and data, as well as to strengthen cooperation among internal and external researchers concerned with this topic, the Forest Regeneration Network (ForReg) was founded in 2022. So far, 32 scientists have joined this network, covering the expertise of experimental research, monitoring, modeling, biodiversity aspects regarding soil-plant and animal-plant interactions, and disturbance ecology.

WSL research on forest regeneration covers the following topics:

  • drivers of regeneration
  • demography in juvenile tree populations
  • environmental niches of juvenile trees
  • browsing effects on juvenile trees
  • competition of invasive alien species on native species
  • improved simulation models
  • improved sampling designs and regeneration indicators
  • silvicultural management for climate change adaptation

Projects

Wie können langfristige Entwicklungen von Waldbeständen und deren Verjüngungszustände systematisch erfasst werden? Das Projekt entwickelt eine standardisierte Methodik und eine spezialisierte Softwarelösung, die Forstpraktikern eine effiziente Datenerhebung ermöglicht.

Das Ziel dieses Initiierungsprojketes ist es das Studendesign und Flächen für Folgeprojekte auszwählen zum Potenzial & den Grenzen von waldbaulichen Anpassungsstrategien zur Reduktion der trockenstressbedingten Mortalität in Buchenbeständen.

Eine Übersicht über minimale und maximale Stammzahlen der Verjüngung in Schweizer Wäldern fehlt. BENCHMARKS soll Bandbreiten von Verjüngungsdichten für Baumarten und Höhenklassen berechnen, differenziert nach Naturraum, Höhenstufen, groben NaiS-Standorttypen und Waldstrukturen.

Der Kanton Freiburg erhebt seit 2003 den Verbiss an der Baumverjüngung mittels Stichproben. Diese Verjüngungsdaten werden zusammen mit Daten der wildlebenden Huftiere analysiert. Zusätzlich werden Daten der schweizerischen Landesforstinventare 1993/1995 und 2009-2017 für diese Region analyisert.

The projected increase in the frequency of forest fires due to climate change underlines the need for long-term studies on tree regeneration and succession after forest fires. These data serve as a basis for adaptive management and intervention plans.

Die Zusammenhänge des Wirkungsgefüges «Baumverjüngung – wildlebende Huftiere – anthropogene Aktivitäten» werden mittels Monitoring von Huftieren und dem Verbisseinfluss auf die Verjüngung in einem stark durch Menschen frequentieren Wald, dem Waldlabor Zürich auf dem Hönggerberg, untersucht.

The MountEx project aims to develop guidance and tools for managing spruce-dominated mountain forests under extreme disturbances. By focusing on resilience and management priorities, MountEx is helping stakeholders prepare for unprecedented challenges for these vital ecosystems.

An Unmanned Aerial Vehicle UAV equipped with a LiDAR sensor will be used to test its potential for regeneration structure assessments in mountain forests. The project aims to combine terrestrial regeneration mapping with LiDAR-based information to assess size, density and location of regeneration.

The project examines how warmer winters and hot-dry summers affect the growth of potential future tree species during the advanced regeneration stage and how this response is modulated by soil properties and soil biotic communities.

Von welchen Faktoren hängt die Häufigkeit der durch Verbiss bedingten Mortalität ab? Einzelbäumchen werden in gezäunten und ungezäunten Vergleichsflächen über Jahre individuell beobachtet. Zudem erfolgt eine Auswertung bestehender Vergleichsflächenpaare aus verschiedensten Regionen der Schweiz.

Die zeitlichen Entwicklung des Einflusses von wildlebenden Huftierarten auf die Baumverjüngung im Schweizer Wald wird abgeschätzt mittels Daten des Schweizerischen Landesforstinventars sowie Dichteschätzungen von Reh, Gams und Rothirsch.

New and improved functionality for the mastweb.ch platform to collect, distribute, visualise and evaluate data on tree fecundity levels in Swiss forests.

The project "Mountain Forest Regeneration" has the long-term goal of creating a technical basis within about 20 years so that natural regeneration in mountain forests can be effectively promoted by silviculture.

With a network of 57 experimental plantations we investigate which tree species will grow well in the Swiss forest under the climatic conditions in 30 - 50 years.

Ungulate browsing is an important driver of forest regeneration in mountain protective forests of the Valle Mesocina.

We investigate seedling emergence and survival of Norway spruce and European larch at treeline in an experiment at Stillberg near Davos.

Exotic tree species, which are adapted to a warmer and dryer climate, could contribute to coping with climate change. Six such species are tested in a long-term field experiment near Mutrux (Canton of Vaud).

Products

TreeMig is a dynamic forest model at landscape level. It simulates how different tree species develop and spread in Switzerland and beyond, taking into account climate, seed dispersal and competition.

Members

Gabor Reiss

Group leader

Management of facilities Birmensdorf

Technical Support and Experimental Garden

WSL Birmensdorf

Dr. Thomas Wohlgemuth

Member of Directors Board; Senior Scientist, interim Head of Research Unit

Forest Dynamics

WSL Birmensdorf

Publikationen

Streit K., Brang P., Frei E.R. (2024) The Swiss common garden network: testing assisted migration of tree species in Europe. Front. For. Glob. Change. 7, 1396798 (15 pp.). https://doi.org/10.3389/ffgc.2024.1396798Institutional Repository DORA

Nikolova P.S., Allgaier Leuch B., Frehner M., Wohlgemuth T., Brang P. (2024) Indikatoren der Waldverjüngung und ihre Anwendungsbereiche. Schweiz. Z. Forstwes. 175(3), 108-115. https://doi.org/10.3188/szf.2024.0108 Institutional Repository DORA

Zani D., Lehsten V., Lischke H. (2022) Tree migration in the dynamic, global vegetation model LPJ-GM 1.1: efficient uncertainty assessment and improved dispersal kernels of European trees. Geosci. Model Dev. 15(12), 4913-4940. https://doi.org/10.5194/gmd-15-4913-2022 Institutional Repository DORA

Kalt T., Nikolova P., Ginzler C., Bebi P., Edelkraut K., Brang P. (2021) Kurzes Zeitfenster für die Fichtennaturverjüngung in Gebirgsnadelwäldern. Schweiz. Z. Forstwes. 172(3), 156-165. https://doi.org/10.3188/szf.2021.0156 Institutional Repository DORA

Vacchiano G., Ascoli D., Berzaghi F., Lucas-Borja M.E., Caignard T., Collalti A., … Hacket-Pain A. (2018) Reproducing reproduction: how to simulate mast seeding in forest models. Ecol. Model. 376, 40-53. https://doi.org/10.1016/j.ecolmodel.2018.03.004 Institutional Repository DORA

Lischke H., Löffler T.J. (2006) Intra-specific density dependence is required to maintain species diversity in spatio-temporal forest simulations with reproduction. Ecol. Model. 198(3-4), 341-361. https://doi.org/10.1016/j.ecolmodel.2006.05.005 Institutional Repository DORA

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