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Weather and climate extremes and drought

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Weather extremes, such as droughts, heatwaves and storms, are becoming more frequent in Switzerland as a result of climate change. Our research is creating a knowledge base for better forecasts and adaptation strategies and investigates the consequences of such events.

Switzerland is already registering more very warm days and fewer very cold nights than fifty years ago. This is in line with expectations: Worldwide, climate change is expected to result in less pronounced cold, but more and more intense heat extremes and heavy precipitation. Events are considered extreme if they deviate markedly from a long-term average. Examples include the dry phase in the summer of 2018 or the floods in July 2021.

Drought and ecosystems

At WSL, we are dedicated to the early detection and impact of such extreme situations on the population and ecosystems. For example, together with the FOEN and MeteoSwiss, we operate the Drought-CH information platform for the early detection of drought. It is aimed at municipalities, hydropower plants and farmers.

Pronounced droughts or other consequences of climate change also have an impact on forests. Without adaptations in their management or species composition, forests will no longer be able to fulfill important functions - such as water treatment or protection against avalanches - to the same extent in the future. We provide basic knowledge so that forest services, managers and policymakers can correctly assess the climate risks and the adaptive capacity of forests and take effective adaptation measures.

With increasing drought, the risk of forest fires is also rising. WSL collects data on forest fires and develops methods for their prevention.

Extreme events such as pronounced heat waves can also have an impact on the economy and society. We are therefore also investigating political and economic strategies and processes, for example for adapting to climate change.

Topics

WSL Drought Initiative 2018

We investigate events and impacts of the 2018 drought and derive lessons for dealing with such situations in the future.

Swiss flood and landslide damage database

Since 1972 we record storm damages in Switzerland in a database. It is financed by the FOEN and helps evaluating risks.

Researching Extremes

This research programme investigates events that occur rather infrequently and irregularly but can nevertheless have a massive impact on the...

Protection forest

We investigate which characteristics of a forest determine its protective capacity, and how these could alter with climate change.

Forest and Climate Change

We assess the impacts of climate change on forestry and forest ecosystems and develop solutions for dealing with the changes.

CERC Research Centre

We develop solutions to problems that arise in mountain regions due to the consequences of climate change, extreme events and natural hazards.

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Research Groups

Publications

Bose, L., 2020: Forest under stress. WSL magazine Diagonal, 2020, 2: 18-20.

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Salazar-Tortosa, D.; Castro, J.; Saladin, B.; Zimmermann, N.E.; Rubio De Casas, R., 2020: Arid environments select for larger seeds in pines (Pinus spp.). Evolutionary Ecology, 34: 11-26. doi: 10.1007/s10682-019-10016-1

Charpentier Ljungqvist, F.; Thejll, P.; Björklund, J.; Gunnarson, B.E.; Piermattei, A.; Rydval, M.; Seftigen, K.; Støve, B.; Büntgen, U., 2020: Assessing non-linearity in European temperature-sensitive tree-ring data. Dendrochronologia, 59: 125652 (16 pp.). doi: 10.1016/j.dendro.2019.125652

Speich, M.J.R.; Zappa, M.; Scherstjanoi, M.; Lischke, H., 2020: FORests and HYdrology under Climate Change in Switzerland v1.0: a spatially distributed model combining hydrology and forest dynamics. Geoscientific Model Development, 13, 2: 537-564. doi: 10.5194/gmd-13-537-2020

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Projects

Consecutive drought-flood events in a warming world

This project aims to enhance our understanding of rapid drought-flood transitions in a warming world.

Floods and droughts under global change

This project aims to enhance our understanding and modeling capability of regional hydrologic extremes in the Alps in a global change context.

Bark beetle infestation in protective forests

This project aims at improving the early detection of bark beetle damage in forests in the canton of Grisons as well as the prioritisation of management against bark beetle infestation in protective forests in the long term.

Digiforest

The mission of DIGIFOREST is to develop the technology needed to achieve sustainable digital forestry. It includes fundamental science for mobile robotic navigation (multi-sensor motion tracking, 3D mission planning etc.) and data-driven semantic mapping.

TreeWater - Disentangling the isotopic signal transfer from source water to tree rings

TreeWater aims to improve our understanding of whether and how information on water uptake dynamics can be retrieved from the oxygen and hydrogen (i.e. water) isotopes in tree rings.

Acceptance of management and policy options for resilient forests (ABePo)

The project examines in two case study regions (Canton Berne and Canton Aargau) forest owners' acceptance of various forest management and policy options concerning increasing extreme disturbances in the forest.

Adhoris

We will provide an overview where and how high resolution, kilometer scale, climate data can provide new insights from climate change impact models. To do so, we will use a set of climate impact models across several sectors, ranging from dynamic vegetation, to hydrology, or biodiversity models.

CCAMM II: Cascading Processes

The CCAMM cluster "Cascading Processes"develops knowledge and models that can be used to anticipate future cascading events. At "Spitze Stei", Kandersteg BE, we study the cascading processes: rock slope instability, debris flow, rock/snow avalanches and lake outburst floods.

MountEx

The MountEx project, part of the WSL research program Extremes, aims to develop guidance and tools for managing spruce-dominated mountain forests under the influence of previously unthinkable, extreme disturbances.

ProtoAIM - Enhanced Plot Design for Advanced Inventorying and Monitoring

We will enhance the design of the Swiss NFI plots to accomodate an augmented series of measurements, sampling and analysis needed to respond to pressing research question on status and change of the Swiss forest.

EMERGE - Extreme droughts in mountain regions

EMERGE will investigate the impacts of historic megadroughts on water fluxes and ecosystems in mountain regions, and use this knowledge to develop stress-test scenarios for a possible future megadrought in the Swiss Alps.

Drought and flood statistics in regulated catchments

This project aims to enhance our understanding of the statistical behavior of multivariate hydrologic extremes in the Alps in a global change context where streamflow is increasingly regulated through reservoir operation or water abstraction.

Extreme Schneehöhen in der Schweiz

Räumlich hoch aufgelöste Schneehöhenkarten für Wiederkehrdauern von 10 bis 300 Jahren als Grundlage für die Bestimmung von Schneelasten und die Dimensionierung von Lawinenverbauungen und Bauwerken.

ONEforest

ONEforest develops a multi-criteria planning system for strategic decision makers from forestry, politics and industry and provides information regarding potential social, ecologic and ecologic and economic impacts of alternative forest management options in a medium to long-term perspective.

Sentinel-2 vegetation height models

The aim of the project is to generate annual vegetation height models for Switzerland based on satellite imagery from Sentinel-2. Within the framework of the Swiss NFI, a workflow will be implemented and the accuracy of the resulting products will be estimated.

ICOS-2: Integrated Carbon Observation System in Switzerland, Phase 2017-2021

Die Forschungsstation Seehornwald Davos wurde in den 80er-Jahren von der WSL initiiert und ist damit eine der ältesten permanent betriebenen Wald-Vegetations-Forschungsstationen in der Schweiz.

Global change effects on food webs

Food-web structure is likely affected by global change with consequences for biodiversity and ecosystem functioning. In this project we study changes in food webs and nutrient fluxes in response to global change drivers in aquatic, terrestrial and interconnected habitats.

SCC II - REACT

Species-specific reactions of temperate European forest trees to a changing environment. A project related to the Swiss Canopy Crane II (SCC II) site near Basel and the network TreeNet.

Copernicus Land Monitoring 2021-2025

Das vom BAFU finanzierte Projekt verfolgt die laufenden Entwicklungen im Bereich Copernicus Land Monitoring Services aktiv. Dies umfasst den wissenschaftlichen und technischen Support im Bereich Landbedeckung / Landnutzung auf schweizerischer und europäischer Ebene.

Invasiveness of T. fortunei in the forests of southern Switzerland

The invasion of ecosystems by non-native species is one of the largest threats for biodiversity and ecosystem functioning worldwide. To control the spread of non-native plants, it is crucial to understand by which mechanisms they outperform native vegetation. Yet, despite the considerable applied re

Polytunnel Greenhouse Experiment

Das Projekt untersucht, wie gut zukunftsfähige Baumarten während der Verjüngungsphase in einem Klima mit wärmeren Wintern und heiss-trockenen Sommermonaten wachsen, wie sie sich gegenseitig beeinflussen und welche Auswirkungen ihre Präsenz auf den Boden und die darin lebenden Organismen hat.

New basics for the forest management planning of staged forests

Based on forest roads, forest structures and ecosystem services to be provided, this project will develop new basics for the separation of management and operation units as a planning basis for mountain and permanent forests.

Partitioning of resources between beech trees during drought

We will examine whether recent drought events shifted the partitioning of growth among tree size classes of beech trees and use this information to develop thinning strategies for mitigating drought impacts in lowland and montane Swiss beech forests

Regional warnings for slope instabilities: Napf pilot study

In this project, elements of regional landslide early warning are applied in a pilot early warning system in the Napf region, and their added value for such early warning systems is assessed.

Remote sensing-based national forest damage assessment system

In the FNEWs project, a national remote sensing-based monitoring system for forest damage is being set up for Germany. In the WSL's work package the potentials of Sentinel-1 C-band data are analysed, demonstrated and operational procedures are designed.

drought.ch @ BAFU

Das Ziel dieses Projekts ist die Erarbeitung eines Konzeptes für die Überführung von Elementen der bestehenden Forschungsplattform drought.ch in den operationellen Betrieb beim BAFU sowie eine Integration bei naturgefahren.ch.

Feedbacks between Biodiversity and Climate

Despite being an essential element of the biodiversity and climate change crisis, the feedback between biodiversity and climate remains an understudied subject in biodiversity and climate science. The project FeedBaCks will focus on this important interaction between the two disciplines.

Impacts of climate change induced extreme windthrow events on forest management and economy of European forest enterprises (ExWiFE)

An increase of extreme environmental disturbances is expected, which is for different reasons a big challenge for forest stakeholders on the operating-, strategic-, financial- and environmental level. Using diverse methods, we aim to describe the complexity of the current problem.

MACHINE LEARNING AIDED FORECASTING OF SUBSEASONAL DROUGHT INDICATORS IN THE EUROPEAN ALPS

This research aims to explore the predictability of drought at a monthly time horizon in the form of low flow in Switzerland and the European Alps by using machine learning techniques and linking large scale weather patterns with local hydrological events.

Drought & beech: Effects of the 2018 summer drought on beech on the northern side of the Alps

In this project, we investigate causes for the impacts of the extreme summer drought 2018 on the vitality of beech trees in different regions of the Swiss Plateau and Jura.

Wasserkraftwerkportfolio "ewz"

Für die Elektrizitätswerk der Stadt Zürich ("ewz") soll eine Übersicht zum zukünftigen Wasserdargebot in den Kraftwerke ihren Portfolio erstellt werden. Die Ergebnisse sollen für den heutigen und künftigen Wasserverfügbarkeit bereitgestellt werden.

Wasserdargebot Kanton Zürich

In dieser Studie wurden anhand der CH2018 Klimaszenarien und den hydrologischen Projektionen Hydro-CH2018, Abflussszenarien (also das zukünftige Wasserdargebot) für den Kanton Zürich erstellt.

Wasserbilanz der Schweiz

Modellgestützte Bilanzierung des Wasserhaushaltes der Grosseinzugsgebiete der Schweiz

UAV-based monitoring of physiological tree responses

In this project, we investigate the potential of spectral proxies, obtained from unmanned aerial vehicles (UAV) high-resolution multispectral and thermal imaging, to detect trees pre-visual drought stress responses.

eLTER Switzerland

The Long-Term Ecologiocal Research in Europe (LTER-Europe) capitalizes on research infrastructures such as the in-situ network of sites and information technology. Thousands of research projects have been carried out taking advantage of this infrastructure.

High-resolution soil maps for the Swiss forest

In this project we model high-resolution soil maps with different soil properties such as pH or texture for the entire Swiss forest.

Alpine Drought Obvservatory

According to the Alpine Convention, water scarcity and related conflicts are becoming a worrying topic in many Alpine regions, depending on water from snowmelt and glaciers.

Niedrigwasserdauerkurven

Der Bedarf nach einer solideren Grundlage für die Abschätzung von Niedrigwasserabflüssen in ungemessenen Gebieten ist im Nachgang zu den Trockenheitsereignissen der Jahre 2003, 2011, 2015 und 2018 gestiegen. Die massgebenden Speicher und Einflussfaktoren wie zum Beispiel Versickerungsstrecken werden

On future water resources in Switzerland"

Continuing climate change modifies the water supply and accentuates the pressure from competing water uses.

Seeregulierung und Klimawandel

Mit den vorgesehenen Untersuchungen soll die Wirksamkeit der Seeregulierungs-Vorschriften basierend auf den Klimaszenarien CH2018 überprüft werden. Eine mehrstufige Studie klärt den Handlungsbedarf bei den Regulier-Reglementen.

Drought influence on lightning-induced fires

In a changing climate, lightning-caused wildfires might increase in Switzerland over the next decades. Our studies aim at understanding patters and conditions under which these fires develop.

Mehrzweckspeicher als Zukunftsmodell?

Obwohl die Schweiz über reichlich Wasser verfügt, kann es zukünftig lokal zu Engpässen kommen. Mehrzweckspeicher stellen eine Möglichkeit dar, um auf zukünftige Wasserknappheit zu reagieren. Dieses Projekt untersucht die Chancen und Risiken einer gemeinsamen Bewirtschaftung.

Storm damage indication map

Remote sensing methods allow a rapid, wide-area and objective overview of the forest damage after a storm event.

Give and take: how much water does soil retain for trees?

Establishing an inventory of soil water availability to trees in Swiss forest soils. This is done by means of model-based analysis of the water balances at 16 long-term monitoring sites in Switzerland, representing various geographical locations, soil and vegetation types.

Waldlabor Zürich

Das Waldlabor Zürich ist ein erlebnisorientierter Bildungs- und Forschungsort, es ist das erste Waldlabor der Schweiz. Im Zentrum steht der vom Menschen beeinflusste Wald, der "Kulturwald" mit verschiedenen Formen der Waldpflege und -bewirtschaftung, der Leistungen der Waldeigentümer und der Bedeutu

CCAMM Task 1.0: Downscaling Meorological forcings.

The WSL program Climate Change Impacts on Alpine Mass Movements (CCAMM) comprises projects covering a range of topics in natural hazards. Most investigations use models and thus require climate forcing data. The aim of this task is to provide meteorological forcings at the slope scale and in high temporal resolution.

Mal dell'inchiostro del castagno

Lo scopo di questo progetto è quello di determinare l'effetto dei cambiamanti climatici sulla diffusione e l'incidenza del mal dell''inchiostro del castagno al sud delle Alpi della Svizzera.

XELLCLIM

We identify the best xylem cell anatomical features for climate reconstructions and assess their characteristics across temporal scales compared to established tree-ring parameters, and against instrumental records and climate model simulations.

SwissSPOT- Swiss forest Soil water POTential network

SwissSPOT is a network to monitor soil water down to 2m soil depth at Swiss Long-term Forest Ecosystem Research (LWF) sites.

Towards automated monitoring of alpine mass movements

This project aims at setting up an interactive network of autonomously communicating instruments to capture processes happening during and directly after alpine mass movements.

Adaptation of trees to extreme climate events

Extreme climate events are expected to become more frequent with climate warming. We test genetic differentiation in resistance to late frost and drought in silver fir populations planted in the 1980s in Swizterland and abroad.

QUPFIS

Our aim is to estimate Swiss forest net ecosystem productivity (NEP) at monthly or seasonal resolution for each individual year in order to link biomass changes over time with global drivers.

Risks for small hydropower plants associated with climate change

estimate the impact of climate change on the inflow in a snowmelt dominated tributary of a small hydropower plant using a stochastic 2-dimensional weather generator, a high-resolution energy balance snow cover and a gridded hydrological model

Hydro-CH2018: Multiple use of reservoirs

This synthesis work aims at identifying the potential of reservoirs (such as natural and artificial lakes, storage dams and other reservoirs) to mitigate future drought situations both at the national (Swiss) scale, but also for specific case study areas.

HYDRO-CH2018 "Forhycs-Ice"

In the project FORHYCS-ICE, ("Forest, Glacier and Hydrology Change in Switzerland"), we aim at providing the first holistic simulations of climate impacts (CH2018 scenarios) on water resources, glaciers and forests.

MicroVegSnow

With a view to improving climate and weather forecasts as well as disaster prevention, ESA determines the water content in upper soil layers worldwide. A research project carried out in the Swiss Alps will now investigate how these satellites could be used to measure data about snow as well as frost in the soil.

Insights into streamflow generation mechanisms

To study streamflow generation mechanisms in steep mountainous catchments, we installed a «lab in the field» for monitoring stable water isotopes and water quality in streamflow and precipitation at 30-min resolution.

Prediction of hydrological drought

SREP-drought will evaluate how summer low flows and droughts are affected by winter snowpack in three catchments (Prealps, central Switzerland; Jizera Mountains, northern Czech Republic; Little Caucasus, central Georgia).

FORHYCS

A hydrological model is coupled to a forest model to better assess the influence of changing drivers to forests and the hydrological cycle

Understory removal experiment Salgesch

Long-term research on the interactions between changes in land use and climate and their consequences regarding forest health and dynamic in the pine forests at low elevation of Central Alps

DROUGHT CH

Droughts and heat waves are expected to become more frequent in Switzerland due to climate change. Droughts have major impacts on water resources, public health, ecosystems and consequently the economy. However, information about relevant economic and societal impacts and knowledge about adequate coping strategies are still lacking.

Soil as a site factor

This project delivers soil and site related information for Swiss forests which are based mainly on measured values: (i) response of tree species relating to direct and indirect environmental variables, (ii) quantitative characterisation of species' ecological niche and (iii) soil ecological indicator values for forest plant species.

Tree regeneration after windthrow

Wind disturbance is the main natural driver of forest stand dynamics in Central and Northern Europe. On the basis of a large sample of windthrow gaps, this project aimed to quantify natural tree regeneration after wind disturbance, and to identify factors influencing tree regeneration dynamics.

Germination experiment

Recent Scots pine mortality in forests of the upper Rhone valley have been suggested to be caused by climate change. In an ongoing PhD study, effects of different climate parameters and interspecific competition on the regeneration of both Scots pine (Pinus sylvestris) and black pine (Pinus nigra) are tested.

Consequences of "Lothar" to interest groups

The storm Lothar has had consequences for totally different groups interested in the forest. These are not only groups economically linked with the forest, but also people, which use the forest in their leisure time. Which consequences did "Lothar" have for the different interest groups?

Perception of natural hazards

With a telephonic survey the Swiss inhabitant's perception of natural hazards and specifically the hurricane "Lothar" has been investigated. The scientists asked almost 1000 people.

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Services and products

Drought.ch / trockenheit.ch

Die Informationsplattform zur Früherkennung von Trockenheit in der Schweiz drought.ch liefert Informationen zu aktueller und bevorstehender Trockenheit, resp. Wasserressourcendefizit. Es handelt sich dabei nicht um offizielle Warnungen.

FORTE app: online tools for forests today and tomorrow

How are forests doing today, and how will they cope with climate change in 15 or 40 years from now – in my town or my region? Forest managers and owners, decision-makers, teachers and otherwise interested citizens can find comprehensive answers via FORTE and FORTE Future, the new one-stop online tools developed by WSL as part of the Swiss National Center for Climate Services.

Person in charge: Arthur Gessler