Christof Bigler

Last Name

Bigler

First Name

Christof

ORCID

0000-0003-3757-6356

Organisational unit

03535 - Bugmann, Harald / Bugmann, Harald

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Publications1 - 10 of 92

Changes in litter and dead wood loads following tree death beneath subalpine conifer species in northern Colorado
Bigler, Christof; Veblen, Thomas T. (2011)
Canadian Journal of Forest Research
Light availability predicts mortality probability of conifer saplings in Swiss mountain forests better than radial growth and tree size
Bianchi, Eva; Bugmann, Harald; Bigler, Christof (2021)
Forest Ecology and Management
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 living and dead saplings of four coniferous tree species (Pinus cembra, Larix decidua, Picea abies, Abies alba) in nine forests along an elevational gradient of the Swiss Alps. Based on tree-ring widths reconstructed from stem disks at multiple tree heights, we calculated radial growth rates. We observed a divergent pattern in radial growth of living and dead saplings, with reduced growth of dead saplings starting several years prior to death. By matching living and dead saplings of similar ages, we tested whether mortality probabilities of saplings were influenced by light availability, recent growth rates and diameter. Mortality of coniferous saplings in mountain forests was mainly influenced by light availability, with changing effects along the elevational gradient. Recent radial growth rate and tree size were only weakly associated with sapling mortality. Our study establishes the importance of long-term predisposing factors for the mortality probability of conifer saplings in mountain forests, thus extending well-established findings from the adult stage to saplings, which represent a critical stage of forest dynamics.
Site-specific water-use strategies of mountain pine and larch to cope with recent climate change
Churakova, Olga V.; Saurer, Matthias; Bryukhanova, Marina V.; et al. (2016)
Tree Physiology
Zukunftsfähige Baumarten an der trockenen Waldgrenze
Bernath, Mark; Bigler, Christof; Pfammatter, Ferdinand; et al. (2026)
Schweizerische Zeitschrift für Forstwesen
An der Lötschberg-Südrampe, einem steilen Südhang im Kanton Wallis, wachsen teilweise bewässerte Schutzwälder, die die Bahnlinie vor Naturgefahren schützen. Aufgrund des Klimawandels wächst die Sorge, ob dieser Wald auch in Zukunft seine Schutzfunktion in diesem trockenen inneralpinen Tal erbringen kann. Um zukunftsfähige Baumarten zu identifizieren, wurden 2012/2013 an drei Standorten 2160 Bäume von neun einheimischen und nicht einheimischen Baumarten gepflanzt, wobei die Hälfte davon bewässert wurde. Die Resultate dieses Aufforstungsexperiments haben gezeigt, dass Blumenesche, Flaumeiche, Douglasie und Waldföhre sich am besten eignen, um auf diesen Trockenstandorten zukunftsfähige Bestände aufzubauen. Hierzu werden vier Bewirtschaftungsstrategien vorgestellt, die verschiedene Rahmenbedingungen der Waldbewirtschaftung berücksichtigen: dauerhafte Bewässerung, keine Bewässerung, Bewässerung in den ersten Jahren sowie Verjüngung unter Schirm.
Predicting tree mortality from growth data
Wunder, Jan; Reineking, Björn; Bigler, Christof; et al. (2008)
Journal of Ecology
Abiotic and biotic determinants of height growth of Picea abies regeneration in small forest gaps in the Swiss Alps
Schmid, Ueli; Bigler, Christof; Frehner, Monika; et al. (2021)
Forest Ecology and Management
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 on height growth of regeneration at the scale of forest gaps are thus needed. However, there is a lack of such data for trees of intermediate sizes, and existing studies fail to cover large environmental gradients. The goal of our study is to identify the key factors that influence height growth of Norway spruce regeneration in small gaps of spruce-dominated forests in the Swiss Alps. Furthermore, we assess whether there are site-specific differences of height growth or whether it follows a similar pattern along a large gradient of temperature (i.e., along elevation) and of water and nutrient availability (i.e., among different phytosociological site types) within the upper montane and subalpine vegetation belts. On 124 plots, >2′000 observations of annual height increments of Norway spruce regeneration (10 cm tree height to 12 cm stem diameter) in gaps were collected. Using linear mixed effects models and cross-validation for model selection, we identified the best variable combinations to predict annual height growth. Consistently across the entire gradient, the most important factors were 1) the positive effect of tree size, 2) the negative effect of competition by the surrounding stand, and 3) local topography. We found site-specific differences in height growth patterns such as gap size and therefore direct radiation being the most important competition measure in subalpine sites, as opposed to diffuse radiation in high montane sites. However, the pooled model for the entire environmental gradient allowed for predictions of regeneration height growth with similar explanatory power as the more specific models while containing comparable effect sizes. Furthermore, competition can be equally well expressed by metrics based on basal area measurements as by metrics derived from hemispherical photography. Based on these relatively simple models, accurate and robust predictions of the development of Norway spruce regeneration in gaps of managed mountain forests are possible.
Optimisation of tree mortality models based on growth patterns
Wunder, Jan; Bigler, Christof; Reineking, Björn; et al. (2006)
Ecological Modelling
Early emergence increases survival of tree seedlings in Central European temperate forests despite severe late frost
Bianchi, Eva; Bugmann, Harald; Bigler, Christof (2019)
Ecology and Evolution
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 timing of emergence represents a trade‐off for seedling survival between minimizing frost risk and maximizing the length of the growing period. Almost two‐thirds of the seedlings died during the first growing period. The timing of emergence was decisive for seedling survival. Although seedlings that emerged early faced a severe late frost event, they benefited from a longer growing period resulting in increased overall survival. Larger seedling height and higher number of leaves positively influenced survival. Seedlings growing on moss had higher survival compared to mineral soil, litter, or herbaceous vegetation. Synthesis. Our findings demonstrate the importance of emergence time for survival of tree seedlings, with early‐emerging seedlings more likely surviving the first growing period.
Forest and woodland replacement patterns following drought-related mortality
Batllori, Enric; Lloret, Francisco; Aakala, Tuomas; et al. (2020)
Proceedings of the National Academy of Sciences of the United States of America
Forest vulnerability to drought is expected to increase under anthropogenic climate change, and drought-induced mortality and community dynamics following drought have major ecological and societal impacts. Here, we show that tree mortality concomitant with drought has led to short-term (mean 5 y, range 1 to 23 y after mortality) vegetation-type conversion in multiple biomes across the world (131 sites). Self-replacement of the dominant tree species was only prevalent in 21% of the examined cases and forests and woodlands shifted to nonwoody vegetation in 10% of them. The ultimate temporal persistence of such changes remains unknown but, given the key role of biological legacies in long-term ecological succession, this emerging picture of postdrought ecological trajectories highlights the potential for major ecosystem reorganization in the coming decades. Community changes were less pronounced under wetter postmortality conditions. Replacement was also influenced by management intensity, and postdrought shrub dominance was higher when pathogens acted as codrivers of tree mortality. Early change in community composition indicates that forests dominated by mesic species generally shifted toward more xeric communities, with replacing tree and shrub species exhibiting drier bioclimatic optima and distribution ranges. However, shifts toward more mesic communities also occurred and multiple pathways of forest replacement were observed for some species. Drought characteristics, species-specific environmental preferences, plant traits, and ecosystem legacies govern postdrought species turnover and subsequent ecological trajectories, with potential far-reaching implications for forest biodiversity and ecosystem services.
Disentangling the effects of competition and climate on individual tree growth: A retrospective and dynamic approach in Scots pine
Sánchez-Salguero, Raul; Linares, Juan C.; Camarero, J. Julio; et al. (2015)
Forest Ecology and Management

Publications1 - 10 of 92

Christof Bigler

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