Swiss Federal Institute for Forest, Snow and Landscape Research

About: Swiss Federal Institute for Forest, Snow and Landscape Research is a facility organization based out in Birmensdorf, Switzerland. It is known for research contribution in the topics: Climate change & Soil water. The organization has 1256 authors who have published 3222 publications receiving 161639 citations. The organization is also known as: WSL.

Species‐specific tree growth responses to 9 years of CO2 enrichment at the alpine treeline

Abstract: 1. Using experimental atmospheric CO(2) enrichment, we tested for tree growth stimulation at the high-elevation treeline, where there is overwhelming evidence that low temperature inhibits growth despite an adequate carbon supply. We exposed Larix decidua (European larch) and Pin us mugo ssp. uncinata (mountain pine) to 9 years of free-air CO(2) enrichment (FACE) in an in situ experiment at treeline in the Swiss Alps (2180 m a.s.l.). 2. Accounting for pre-treatment vigour of individual trees, tree ring increments throughout the experimental period were larger in Larix growing under elevated CO(2) but not in Pinus. The magnitude of the CO(2) response in Larix ring width varied over time, with a significant stimulation occurring in treatment years 3-7 (marginal in year 6). 3. After 9 years of treatment, leaf canopy cover, stem basal area and total new shoot production were overall greater in Larix trees growing under elevated CO(2), whereas Pinus showed no such cumulative growth response. The Larix ring width response in years 3-7 could have caused the cumulative CO(2) effect on tree size even if no further stimulation occurred, so it remains unclear if responsiveness was sustained over the longer term. 4. Larix ring width was stimulated more by elevated CO(2) in years with relatively high spring temperatures and an early snowmelt date, suggesting that temperatures were less limiting in these years and greater benefit was gained from extra carbon assimilated under elevated CO(2). The magnitude of CO(2) stimulation was also larger after relatively high temperatures and high solar radiation in the preceding growing season, perhaps reflecting gains due to larger carbon reserves. 5. Synthesis. Contrasting above-ground growth responses of two treeline tree species to elevated CO(2) concentrations suggest that Larix will have a competitive advantage over less responsive species, such as co-occurring Pinus, under future CO(2) concentrations. Stimulation of Larix growt might be especially pronounced in a future warmer climate.

Advantages and disadvantages of techniques for transforming and analyzing chiropteran echolocation calls

Abstract: Bat researchers currently use a variety of techniques that transform echolocation calls into audible frequencies and allow the spectral content of a signal to be viewed and analyzed. All techniques have limitations and an understanding of how each works and the effect on the signal being analyzed are vital for correct interpretation. The 3 most commonly used techniques for transforming frequencies of a call are heterodyne, frequency division, and time expansion. Three techniques for viewing spectral content of a signal are zero-crossing, Fourier analysis, and instantaneous frequency analysis. It is important for bat researchers to be familiar with the advantages and disadvantages of each technique.

Global change effects on land management in the Mediterranean region

Abstract: The Mediterranean region faces significant challenges to supply its growing population with food and living space. The region’s potential to do so in the future is even more uncertain in the light of global change effects. Climate change will impact water availability in the region, which is already limited and often used at unsustainable rates. To investigate the effects of global change and explore alternative development pathways of Mediterranean land use, we simulated two future scenarios with different land, water and biodiversity management transitions. We adopted a land systems approach, where land use and land cover are combined with data on land management, irrigation and livestock density, taking into account the characteristics of Mediterranean multifunctional landscapes, specific agricultural products, such as permanent crops, and irrigation water demands. Future land system changes were explored using the CLUMondo model for different development pathways of the region. We constrained the withdrawal of irrigation water based on existing freshwater resources. In a ‘growth’ scenario, we simulated a hypothetical future without consideration of environmental constraints and where food production and urban expansion are main priorities. The ‘sustainability’ scenario represents a future where limited water resources are extracted in a sustainable way and where areas of high biodiversity value are protected. The growth scenario projected significant intensification of land management, and loss of agro-silvo-pastoral mosaic systems. To achieve this, we calculate that the region would need to increase water withdrawal for irrigation significantly, resulting in increased pressure on freshwater resources. The sustainability scenario presents a way of increasing food production and at the same time improving the state of water resources, wetlands and traditional landscapes. Achieving this future would require improvements of yields of rain-fed systems and efficiencies of irrigated systems. The results indicate that coordinated environmental policy together with appropriate market access are needed to steer the regions land management towards a more sustainable future while ensuring food production.

Seasonal drivers of understorey temperature buffering in temperate deciduous forests across Europe

Abstract: Aim: Forest understorey microclimates are often buffered against extreme heat or cold, with important implications for the organisms living in these environments. We quantified seasonal effects of understorey microclimate predictors describing canopy structure, canopy composition and topography (i.e., local factors) and the forest patch size and distance to the coast (i.e., landscape factors). Location: Temperate forests in Europe. Time period: 2017-2018. Major taxa studied: Woody plants. Methods: We combined data from a microclimate sensor network with weather-station records to calculate the difference, or offset, between temperatures measured inside and outside forests. We used regression analysis to study the effects of local and landscape factors on the seasonal offset of minimum, mean and maximum temperatures. Results: The maximum temperature during the summer was on average cooler by 2.1 degrees C inside than outside forests, and the minimum temperatures during the winter and spring were 0.4 and 0.9 degrees C warmer. The local canopy cover was a strong nonlinear driver of the maximum temperature offset during summer, and we found increased cooling beneath tree species that cast the deepest shade. Seasonal offsets of minimum temperature were mainly regulated by landscape and topographic features, such as the distance to the coast and topographic position. Main conclusions: Forest organisms experience less severe temperature extremes than suggested by currently available macroclimate data; therefore, climate-species relationships and the responses of species to anthropogenic global warming cannot be modelled accurately in forests using macroclimate data alone. Changes in canopy cover and composition will strongly modulate the warming of maximum temperatures in forest understories, with important implications for understanding the responses of forest biodiversity and functioning to the combined threats of land-use change and climate change. Our predictive models are generally applicable across lowland temperate deciduous forests, providing ecologically important microclimate data for forest understories.

The influence of ozone and nutrition on δ13C in Betula pendula.

Abstract: In the cellulose of stems and leaves, δ13C was investigated in a birch clone (Betula pendula), which was exposed throughout the growing season to either <3 (control) or 90/40 nl O3 1-1 (day/night). Each regime was split into plants under high or low nutrient supply. δ13C was increased (becoming less negative), in stems rather than leaves, by both high nutrition (+2‰) and O3 stress (+1‰). Whereas high nutrition raised the wateruse efficiency (WUE) while lowering the CO2 concentration in the inner leaf air space (c i), WUE decreased and c i increased under O3 stress. Therefore, only the nutritional effect on the carbon isotope fractionation was reproduced by the model of Farquhar et al. (1982) which estimates WUE by means of δ13C based on c i. c i was not biased by ‘patchiness’ in respect to stomatal opening. The latter was verified by microscopical analysis and the complete water infiltration of the birch leaves through the stomata, independent of the diurnal course of the leaf conductance for water vapour. Under low nutrient supply, the activity of phosphoenol pyruvate carboxylase (PEPC) was roughly doubled by ozone to about 1.3% of the total carboxylation capacity (by PEPC + rubisco), and was increased to 1.7% under high nutrition. The fractionation model, extended to account for varying activities of the carboxylating enzymes, indicated that stimulated PEPC was the cause of elevated δ13C, although c i was increased under O3 stress. The stimulation of PEPC and, as a consequence, elevated δ13C are discussed as part of a whole-plant acclimation to O3 stress.