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Harald Bugmann

Harald Bugmann
ETH Zurich | ETH Zürich · Department of Environmental Systems Science

Doctor of Philosophy

About

472
Publications
109,727
Reads
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21,236
Citations
Citations since 2017
129 Research Items
10123 Citations
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201720182019202020212022202305001,0001,500
201720182019202020212022202305001,0001,500
Additional affiliations
October 2009 - present
ETH Zurich
Position
  • Professor (Full)
August 2008 - December 2008
The University of Arizona
Position
  • Guest professor
October 2004 - September 2009
ETH Zurich
Position
  • Professor (Associate)

Publications

Publications (472)
Preprint
Full-text available
While enhanced tree growth over the last decades has been reported in forests across the globe, it remains unclear whether it drives persistent biomass increases of the stands, particularly in mature forests. Enhanced tree growth and stand-level biomass are often linked with a simultaneous increase in density-driven mortality and a reduction in tre...
Chapter
Ungulates browse on plants and may have an influence on tree regeneration. Browsing percentage (the relative number of browsed terminal shoots) captures little of the effective browsing impact on tree regeneration, such as reduction in stem number or loss of tree species in the future stand. The main objective is to present the most important facto...
Preprint
Full-text available
Tree regeneration is a key demographic process influencing long-term forest dynamics. It is driven by many biotic and abiotic factors. Thus, predictions of tree regeneration are challenging because of complex feedbacks along climatic gradients. The stress gradient hypothesis (SGH) and life-history strategies (LHS) provide a framework for assessing...
Article
Die Lichtverfügbarkeit prägt die Verjüngungsdynamik in Wäldern auf Böden mit guter Wasser- und Nährstoffversorgung wesentlich. In der Dauerwaldbewirtschaftung wird die Verjüngung unter dem Schirm der Altbäume eingeleitet. In der Regel bleibt die Beschattung über einen längeren Zeitraum erhalten. Um die Wachstumsmuster unter diesen Verhältnissen auf...
Article
Full-text available
Ecological knowledge on long-term forest dynamics and development has been primarily derived from the study of old-growth forests. Centuries of forest management have decreased the extent of temperate old-growth forests in Europe and altered managed forests. Disentangling the effects of past human disturbances and climate on current species composi...
Article
Full-text available
Climate change impacts on Europe’s forests are becoming visible much sooner than previously anticipated. The increase in natural disturbances leads to tree mortality and raises concerns about the forest’s adaptive potential to sustain vital ecosystem services. In this context, the regeneration phase is crucial and comprises the largest potential to...
Article
Full-text available
Abstract 1. To assess the impacts of climate change on vegetation from stand to global scales, models of forest dynamics that include tree demography are needed. Such models are now available for 50 years, but the currently existing diversity of model formulations and its evolution over time are poorly documented. This hampers systematic assessment...
Data
The Inter-Sectoral Impact Model Intercomparison Project (ISIMIP) provides a framework for the collation of a set of consistent, multi-sector, multi-scale climate-impact simulations, based on scientifically and politically relevant historical and future scenarios. This framework serves as a basis for robust projections of climate impacts, as well as...
Article
Full-text available
Forest models are instrumental for understanding and projecting the impact of climate change on forests. A considerable number of forest models have been developed in the last decades. However, few systematic and comprehensive model comparisons have been performed in Europe that combine an evaluation of modelled carbon and water fluxes and forest s...
Article
Full-text available
Climate-adaptive forest management aims to sustain the provision of multiple forest ecosystem services and biodiversity (ESB). However, it remains largely unknown how changes in adaptive silvicultural interventions affect trade-offs and synergies among ESB in the long term. We used a simulation-based sensitivity analysis to evaluate popular adaptiv...
Article
Seit der Einführung der Praxishilfe «Nachhaltigkeit und Erfolgskontrolle im Schutzwald» (NaiS) in der Schweiz im Jahr 2005 haben sich die Rahmenbedingungen für die Schutzwaldbewirtschaftung grundlegend geändert. Dank der Weiterentwicklung der waldbaulichen Grundlagen sowie einem klar definierten Abgeltungssystem konnte die Schutzwaldbewirtschaftung...
Article
Full-text available
Changes of grazing pressure and climate have been identified as drivers of woody encroachment in subalpine pastures, but disentangling their relative importance remains challenging. It is particularly unclear if grazing alone can mitigate potential climate change impacts on encroachment. We used the dynamic vegetation model LandClim to simulate how...
Article
Full-text available
Low mortality rates and slow growth differentiate shade-tolerant from shade-intolerant species and define the survival strategy of juvenile trees growing in deep shade. While radial stem growth has been widely used to explain mortality in juvenile trees, the leaf area ratio (LAR), known to be a key component of shade tolerance, has been neglected s...
Article
Full-text available
Natural forest regrowth is considered the most cost-effective strategy to promote large-scale forest restoration, but regrowth trajectories and their consequences for nature and people can be highly variable. This uncertainty may obstruct devoting land, time and resources in promoting this restoration approach. Process-based models allow to simulat...
Article
Inmitten der Stadt Zürich entsteht ein großräumig und langfristig angelegtes Reallabor für Wissenstransfer rund um die Themen Waldökosystem und Waldbewirtschaftung. Aus der ursprünglichen Idee eines ,,Kommunikationswaldes“, um der breiten Bevölkerung Wald und Waldbewirtschaftung näherzubringen, entwickelt sich nach und nach eine integrale Plattform...
Article
Full-text available
Tree mortality is key for projecting forest dynamics, but difficult to portray in dynamic vegetation models (DVMs). Empirical mortality algorithms (MAs) are often considered promising, but little is known about DVM robustness when employing MAs of various structures and origins for multiple species. We analysed empirical MAs for a suite of European...
Article
Full-text available
Selection silviculture aims to create and maintain uneven-aged forests with a diameter at breast height (DBH) structure that is balanced at small spatial scales such that the stem number in each DBH class is high enough to replace the harvested and outgrowing trees over time by ingrowth from the next lower class. In these forests, natural regenerat...
Article
Full-text available
Climate change alters the bioclimatic conditions during the growing period of trees directly, but also indirectly by causing shifts in spring and autumn leaf phenology that lead to changes in the timing and length of the growing period. Several studies researched the ecological consequences of direct climate change effects on bioclimatic conditions...
Article
Full-text available
Key message We applied a modified forest gap model (ForClim) to depict changes in stand water transpiration via density reduction as a forest adaptation strategy. This approach is the key to analyzing the ecological resilience to drought, stress-induced mortality, and economic efficiency of managed mixed forest stands in Central Europe. The results...
Article
Full-text available
• Tree regeneration is a key process for long-term forest dynamics, determining changes in species composition and shaping successional trajectories. While tree regeneration is a highly stochastic process, tree regeneration studies often cover narrow environmental gradients only, focusing on specific forest types or species in distinct regions. Thu...
Article
The potential ecological envelope of silver fir (Abies alba Mill.) based on its present distribution suggests a high suitability for moist rather than warm and dry environments. This contrasts with paleoecological evidence reporting its former presence at low elevations under meso-Mediterranean conditions. In this study, we evaluated the growth per...
Article
Full-text available
Being able to persist in deep shade is an important characteristic of juvenile trees, often leading to a strong dominance of shade‐tolerant species in forests with low canopy turnover and a low disturbance rate. While leaf, growth, and storage traits are known to be key components of shade tolerance, their interplay during regeneration development...
Article
Full-text available
Extreme droughts are expected to increase in frequency and severity in many regions of the world, threatening multiple ecosystem services provided by forests. Effective strategies to adapt forests to such droughts require comprehensive information on the effects and importance of the factors influencing forest resistance and resilience. We used a u...
Conference Paper
Full-text available
Forest demographic processes-growth, recruitment and mortality are being altered by global change. The changing balance between growth and mortality strongly influences forest dynamics and the carbon balance. Elevated atmospheric carbon dioxide (eCO 2) has been reported to enhance photosynthesis and tree growth rates by increasing both light-use ef...
Article
Single species forest systems often suffer from low resistance and resilience to perturbations. Consequently, fostering tree species diversity is discussed as an important management approach to address the impacts of changing climate and disturbance regimes. Yet, the effect of the spatial grain of tree species mixtures remains unknown. We asked wh...
Article
Full-text available
Spatial patterns can reveal a lot about ecological processes, but our knowledge of the spatial ecology of tree regeneration at a fine scale is quite limited. Therefore, we studied the spatial patterns of living and dead small trees in two subalpine Norway spruce forest reserves in Switzerland (Scatl`e and B¨odmerenwald) using three types of analyse...
Article
Forest ecosystem models, being widespread science tools and used for forest management decision support are usually evaluated individually against field data sets, while model intercomparison and joint evaluation studies are rare. We tested five forest models according to a harmonized protocol against data from nine forest compartments in the Snĕžn...
Article
Full-text available
1. Understanding the processes that shape forest functioning, structure, and diversity remains challenging, although data on forest systems are being collected at a rapid pace and across scales. Forest models have a long history in bridging data with ecological knowledge and can simulate forest dynamics over spatio-temporal scales unreachable by mo...
Article
Full-text available
In managed mountain forests, height growth of Norway spruce (Picea abies (L.) Karst) regeneration is a decisive factor for the gap-filling process, especially when the silvicultural goal is to provide continuous protection against natural hazards such as snow avalanches or rockfall. For the planning of management interventions, robust predictions o...
Article
Full-text available
The increasing impacts of climate change on forest ecosystems have triggered multiple model‐based impact assessments for the future, which typically focused either on a small number of stand‐scale case studies or on large scale analyses (i.e., continental to global). Therefore, substantial uncertainty remains regarding the local impacts over large...
Article
Forests provide multiple services, and in the face of global change adaptive management strategies are needed, which inevitably must be based on models. However, most locally accurate forest models are tied to the stand scale and cannot readily be applied across large areas. Empirical data for model initialisation are often not available at large s...
Article
Climate change impacts forest functioning and dynamics, and large uncertainties remain regarding the interactions between species composition, demographic processes, and environmental drivers. There are few robust tools available to link these processes, which precludes accurate projections and recommendations for long‐term forest management. Fores...
Article
Full-text available
The process-based model 4C (FORESEE) has been developed over the past 20 years to study climate impacts on forests and is now freely available as an open-source tool. The objective of this paper is to provide a comprehensive description of this 4C version (v2.2) for scientific users of the model and to present an evaluation of 4C at four different...
Article
Changes in tree species composition can have strong effects on ecosystem functioning and the services provided by forests. Empirical observations can provide an improved understanding of the drivers of species population dynamics, yet long-term datasets are scarce in natural forests. This study used inventory data of the Swiss forest reserve networ...
Article
Full-text available
Radial and height growth rates are suitable indicators of impending tree mortality risk of adult trees, but their applicability to saplings remains unknown. We compared radial growth of living and dead saplings of different heights and quantified the effects of light availability, growth and tree size on mortality. We sampled an equal number of liv...
Article
Full-text available
The Colchic rainforest of the Western Caucasus is one of the few temperate rainforests dominated by broadleaf deciduous trees. Understanding natural dynamics of broadleaf-dominated temperate rainforests is essential for their conservation and management. Here, we investigate for the first time the structure, natural disturbance, and recruitment dyn...
Article
Full-text available
Projections of landscape dynamics are uncertain, partly due to uncertainties in model formulations. However, quantitative comparative analyses of forest landscape models are lacking. We conducted a systematic comparison of all forest landscape models currently applied in temperate European forests (LandClim, TreeMig, LANDIS-II, iLand). We examined...
Article
Full-text available
The success of tree regeneration in forests strongly depends on light availability. In structured uneven-aged deciduous forests with continuous cover, radiation regimes in the understorey are typically characterized by low and heterogeneous light transmittance. The competitive ability of juvenile trees in these forests is therefore linked to their...
Article
Wie plant man das Unplanbare? Neue Herausforderungen für die Forstwirtschaft (Essay) Es gibt einen engen Zusammenhang zwischen dem Klima, seiner Variabilität und der Entwicklung der menschlichen Gesellschaft im Holozän. Die Entwicklung der Forstwirtschaft fällt mit dem Maximum der Kleinen Eiszeit zusammen, was die Gültigkeit der Erkenntnisse aus je...
Article
In many regions, drought is suspected to be a cause of Scots pine decline and mortality, but the underlying physiological mechanisms remain unclear. Because of their relationship to ecohydrological processes, δ18O values in tree rings are potentially useful for deciphering long-term physiological responses and tree adaptation to increasing drought....
Preprint
Full-text available
Climate change impacts forest functioning and dynamics, and large uncertainties remain regarding the interactions between species composition, demographic processes, and environmental drivers. There are few robust tools available to link these processes, which precludes accurate projections and recommendations for long-term forest management. Fores...
Article
Full-text available
Mountain forest managers face the challenge to anticipate climate change (CC) impacts across large elevational ranges. For management planning, information on site-specific long-term responses to CC as well as the consequences for protection functions is particularly crucial. We used the process-based model ForClim to provide projections of forest...
Article
Full-text available
Citation: Huber, N., H. Bugmannand V., Lafond. 2020. Capturing ecological processes in dynamic forest models: why there is no silver bullet to cope with complexity. Ecosphere 11(5):e03109. Abstract. Dynamic forest models are a key tool to better understand, assess, and project decadal-to centennial scale forest dynamics. Despite their success, many...
Article
Entwicklung von Mischbeständen mit komplexer Struktur im Klimawandel Im naturnahen Waldbau liegt der Schwerpunkt auf Beständen mit mehreren Baumarten und einer stufigen Struktur. Um deren zukünftige Entwicklung abzuschätzen, sind dynamische Modelle nützlich. Mit der Familie der Gap-Modelle, die ursprünglich aus der Ökologie stammen, sind solche Ana...
Article
Modelle? Brauche ich nicht. Modellieren? Tue ich nicht – oder vielleicht doch? Die wenigsten Menschen würden sich spontan als Modellierer bezeichnen. Modelle werden oft als überaus kompliziert, wenig nützlich und nicht praxisnah eingeschätzt. Wir stellen diese (Vor-)Urteile auf den Prüfstand und zeigen auf, dass Modelle in unserem Alltag unentbehrl...
Article
Borkenkäferdynamik im Klimawandel: die Bedeutung der Landschaftsebene Der Klimawandel wirkt auf die Waldentwicklung direkt über steigende Temperaturen und veränderte Niederschlagsmuster und indirekt über Änderungen im Störungsregime. Wo die Fichte (Picea abies) dominiert, ist der Borkenkäfer ein Schlüsselfaktor in der zukünftigen Waldentwicklung, d...
Article
Tropical forest dynamics can be explained by merely two functional trait axes
Article
In recent decades, changes in fire activity have been observed in Europe. Fires can have large consequences for the provisioning of ecosystem services and for human well-being. Therefore, understanding the drivers of fire occurrence and improving the predictive capability of fire occurrence models is of utmost importance. So far, most studies have...
Article
Light availability below and within forest canopies governs many biological processes. Its estimation, however, is often time consuming, especially in complex canopy structures where vertical profiles of light transmission need to be known to estimate plant performance, habitat suitability or biophysical properties across the canopy. To overcome th...
Article
Full-text available
The response of forest productivity to climate extremes strongly depends on ambient environmental and site conditions. To better understand these relationships at a regional scale, we used nearly 800 observation years from 271 permanent long‐term forest monitoring plots across Switzerland, obtained between 1980 and 2017. We assimilated these data i...
Article
Full-text available
Mortality is a key process of forest ecosystem dynamics and functioning strongly altering biomass stocks and carbon residence times. Dynamic vegetation models (DVMs) used to predict forest dynamics are typically based on simple, largely data-free (‘theoretical’) mortality algorithms (MAs). To improve DVM projections, the use of empirically based MA...
Article
Early detection of bark beetle infestations by remote sensing: what is feasible today? Infestation by the Norway spruce (Picea abies) bark beetle (Ips typographus) in uniform forest stands of the high montane and subalpine stage is a major challenge for management. It is impossible to identify in time all susceptible or already infested spruces in...
Article
Mortality, driven by both climate and disturbance legacies, is a key process shaping forest dynamics. Understanding the mortality patterns in primary forests in the absence of severe disturbances provides information on background natural dynamics of a given forest type under ongoing climate change. This can then be compared to mortality rates in s...
Article
Dynamic vegetation models (DVMs) are important tools to understand and predict the functioning and dynamics of terrestrial ecosystems under changing environmental conditions. In these models, uncertainty in the description of demographic processes, in particular tree mortality, is a persistent problem. Current mortality formulations lack realism an...
Article
Knowledge on the ecology of tree species in both their native and introduced range can increase the understanding of their successful establishment and spread outside the native range. Here, we analysed radial growth patterns of Ailanthus altissima (Mill.) Swingle in two sites in its native range in eastern China and in two sites in the introduced...
Article
Full-text available
Global warming is expected to result in earlier emergence of tree seedlings that may experience higher damages and mortality due to late frost in spring. We monitored emergence, characteristics, and survival of seedlings across ten tree species in temperate mixed deciduous forests of Central Europe over one and a half year. We tested whether the ti...
Article
Full-text available
Future forest composition is uncertain in many areas due to climate change. The spread of non-native species adds to these uncertainties, particularly in forests recently colonised by novel tree species. To anticipate future forest composition, and thus the provision of ecosystem services, a thorough understanding of the factors influencing the est...
Article
Full-text available
Context The relationship between disturbances and diversity remains uncertain, especially in forest landscapes where large spatial extents need to be considered, dynamics are slow, and disturbance interactions are common. Objectives To analyse the individual and combined effects of ungulate browsing and wind disturbance on tree species diversity a...
Article
Full-text available
Assessment of the impact of ungulate browsing on tree regeneration Browsing percentage is an objective and reproducible measure of the frequency of browsing by wild ungulates on tree regeneration. However, this relative number of browsed terminal shoots accounts for little of the effective long-term influence of browsing on tree regeneration. Apart...
Article
Full-text available
Key message Our analysis of short-term growth responses to weather conditions provided evidence that the non-native tree species Ailanthus altissima may have a high growth potential in a warmer and drier environment, as predicted by global warming scenarios. Abstract Non-native tree species may alter ecosystem services in colonized forest communit...
Article
Full-text available
Responses to future changes in climatic and socio-economic conditions can be expected to vary between sectors and regions, reflecting differential sensitivity to these highly uncertain factors. A sensitivity analysis was conducted using a suite of impact models (for health, agriculture, biodiversity, land use, floods and forestry) across Europe wit...
Article
Importance of marteloscopes for practice and teaching in Switzerland Marking is one of the core tasks of silvicultural activity. The decisions made are based on the application of the basic forestry methods, but always include a subjective component, as experience plays an important role. In this context, the “silvicultural God's gaze” in German “w...