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.

Which matters most for the formation of intra-annual density fluctuations in Pinus pinaster : age or size?

Abstract: Key message A new method is proposed to standardize chronologies of intra-annual density fluctuations to improve their intra-annual climatic signal. Abstract In the Mediterranean area, intra-annual density fluctuations (IADFs) are triggered by short-term climatic variations during the growing season. It is known that the formation of these anatomical structures is dependent on age and size, which can represent a problem during the extraction of the environmental signal from IADF chro- nologies. We present a new method using a two-step approach to remove the effect of tree-ring width from IADF chronologies. The climatic signal of IADF chronologies obtained by the proposed method was com- pared with previous methods, using 160 Pinus pinaster tree cores from an even-aged stand on the west coast of Por- tugal. Our results show that the climatic signal of IADF chronologies was strongly affected by the standardization method used, and that it could be improved by removing the effect of the predisposing factors (cambial age and tree- ring width) on IADF formation. Moreover, additional cli- matic information (previous winter precipitation) was only revealed when the effect of tree-ring width was removed from IADF series. Finally, we propose that this new method should be tested for other species and across larger geographical areas to confirm its capacity to remove noise from IADF chronologies and to improve their intra-annual climatic signal.

Ultrasonic acoustic emissions in drought-stressed trees - more than signals from cavitation?

Abstract: Summary • Ultrasonic acoustic emission (UAE) in trees is often related to collapsing water columns in the flow path as a result of tensions that are too strong (cavitation). However, in a decibel (dB) range below that associated with cavitation, a close relationship was found between UAE intensities and stem radius changes. • UAE was continuously recorded on the stems of mature field-grown trees of Scots pine (Pinus sylvestris) and pubescent oak (Quercus pubescens) at a dry inner-Alpine site in Switzerland over two seasons. The averaged 20-Hz records were related to microclimatic conditions in air and soil, sap-flow rates and stem-radius fluctuations de-trended for growth (ΔW). • Within a low-dB range (27 ± 1 dB), UAE regularly increased and decreased in a diurnal rhythm in parallel with ΔW on cloudy days and at night. These low-dB emissions were interrupted by UAE abruptly switching between the low-dB range and a high-dB range (36 ± 1 dB) on clear, sunny days, corresponding to the widely supported interpretation of UAE as sound from cavitations. • It is hypothesized that the low-dB signals in drought-stressed trees are caused by respiration and/or cambial growth as these physiological activities are tissue water-content dependent and have been shown to produce courses of CO2 efflux similar to our courses of ΔW and low-dB UAE.

Soil acidification in southern Switzerland between 1987 and 1997: A case study based on the critical load concept

Abstract: Southern Switzerland with its mainly acidic bedrock is potentially very sensitive to the effects of atmospheric proton input. In addition, this region suffers from relatively high acid deposition originating from the greater Milano area. The soil solution composition at different depths of a cryptopodzolic soil was monitored over a 10 year period with samples collected fortnightly. On the basis of the concept of critical loads of acidity, the molar ratio of base nutrient cations (BC) to aluminum was used as the parameter to assess acidification. Despite characteristic seasonal short-term variations of BC and Al, which could be attributed qualitatively to specific soil chemical processes, statistically significant trends over the entire observation period were observed. In all horizons a depletion of BC concentrations indicated an impoverishment of the nutrient status of the vegetation. Aluminum decreased in the upper soil, whereas a significant increase was observed at the lowest soil depth. The BC/Al rat...