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.

Coordination between growth, phenology and carbon storage in three coexisting deciduous tree species in a temperate forest.

Abstract: In deciduous trees growing in temperate forests, bud break and growth in spring must rely on intrinsic carbon (C) reserves. Yet it is unclear whether growth and C storage occur simultaneously, and whether starch C in branches is sufficient for refoliation. To test in situ the relationships between growth, phenology and C utilization, we monitored stem growth, leaf phenology and stem and branch nonstructural carbohydrate (NSC) dynamics in three deciduous species: Carpinus betulus L., Fagus sylvatica L. and Quercus petraea (Matt.) Liebl. To quantify the role of NSC in C investment into growth, a C balance approach was applied. Across the three species, >95% of branchlet starch was consumed during bud break, confirming the importance of C reserves for refoliation in spring. The C balance calculation showed that 90% of the C investment in foliage (7.0-10.5 kg tree(-1) and 5-17 times the C needed for annual stem growth) was explained by simultaneous branchlet starch degradation. Carbon reserves were recovered sooner than expected, after leaf expansion, in parallel with stem growth. Carpinus had earlier leaf phenology (by ∼25 days) but delayed cambial growth (by ∼15 days) than Fagus and Quercus, the result of a competitive strategy to flush early, while having lower NSC levels.

Quantifying plasticity in vessel grouping – added value from the image analysis tool ROXAS

Abstract: The functional role of the connectivity of the xylem network, especially the arrangement of solitary and grouped vessels in a cross section, has often been discussed in the literature. Vessel grouping may improve hydraulic integration and increase resilience to cavitation through redundancy of hydraulic pathways. Alternatively, a high degree of hydraulic integration may facilitate the spread of cavitations among neighboring vessels. Here we show how automated image analysis tools such as ROXAS (see www.wsl.ch/roxas) may greatly enhance the capacity for studying vessel grouping while avoiding some methodological limitations of previous approaches. We tested the new analysis techniques by comparing the xylem network of two populations of the herbaceous species Verbascum thapsus collected at a dry and moist site on Big Island (Hawaii, USA). ROXAS accurately, objectively and reproducibly detected grouped and solitary vessels in high-resolution images of entire root cross sections, and calculated different and partly novel vessel grouping parameters, e.g. the percentage of grouped (vs. solitary) vessels among different vessel size classes. Individuals at the dry site showed a higher degree of vessel grouping, less solitary vessels, greater maximum vessel sizes and an increase of the percentage of grouped vessels with increasing vessel size. The potential, but also some limitations of automated image analysis and the proposed novel parameters are discussed.

Couplings in cell differentiation kinetics mitigate air temperature influence on conifer wood anatomy.

Abstract: Conifer trees possess a typical anatomical tree-ring structure characterized by a transition from large and thin-walled earlywood tracheids to narrow and thick-walled latewood tracheids. However, little is known on how this characteristic structure is maintained across contrasting environmental conditions, due to its crucial role to ensure sap ascent and mechanical support. In this study, we monitored weekly wood cell formation for up to 7 years in two temperate conifer species (i.e., Picea abies (L.) Karst and Larix decidua Mill.) across an 8°C thermal gradient from 800 to 2,200 m a.s.l. in central Europe to investigate the impact of air temperature on rate and duration of wood cell formation. Results indicated that towards colder sites, forming tracheids compensate a decreased rate of differentiation (cell enlarging and wall thickening) by an extended duration, except for the last cells of the latewood in the wall-thickening phase. This compensation allows conifer trees to mitigate the influence of air temperature on the final tree-ring structure, with important implications for the functioning and resilience of the xylem to varying environmental conditions. The disappearing compensation in the thickening latewood cells might also explain the higher climatic sensitivity usually found in maximum latewood density.