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.

Seasonality of precipitation interacts with exotic species to alter composition and phenology of a semi-arid grassland

Abstract: Summary While modelling efforts suggest that invasive species will track climate changes, empirical studies are few. A relevant and largely unaddressed research question is ‘How will the presence of exotic species interact with precipitation change to alter ecosystem structure and function?’ We studied the effects of changes in seasonal timing of precipitation on species composition and resource availability in a grassland community in Colorado, USA. We examined how seasonal precipitation patterns affect the abundance of historically present (native) and recently arrived (exotic) plant species, as well as soil moisture, nitrogen and above-ground biomass. Over 4 years, we applied four precipitation treatments based on climate model predictions for the study area: winter-wet/summer-ambient, winter-wet/summer-dry, winter-wet/summer-wet and winter-dry/summer-wet. Cover of exotic winter-active grasses was greater in winter-wet treatments than in control or winter-dry treatments. Cover of native warm-season grasses and forbs was greatest in the winter-dry/summer-wet treatment, and lowest in the winter-wet/summer-dry treatment. These results support the expectation that increased winter precipitation benefits new arrivals, whereas increased summer precipitation benefits later-growing native plants. Structural equation models showed that interactive effects of increased winter precipitation and increased cover of winter-active grasses reduced growing season soil water content and species diversity. In addition, the dominant winter-active species, Bromus tectorum, flowered and senesced earlier in plots receiving increased winter precipitation and reduced summer precipitation, suggesting that earlier growth of winter-active grasses decreases available soil resources and impacts later-growing native plants. Peak above-ground biomass was lowest in the treatment receiving reduced summer precipitation, but only in years with dry springs. Plant-available nitrogen in spring was lower in plots receiving supplemental winter precipitation, and highest in plots with reduced winter precipitation. Synthesis. Our results indicate that altering the seasonality of precipitation can have large direct effects on plant community composition and phenology, as well as significant indirect effects, mediated through exotic species, on plant-available resources and plant interactions.

Standardizing the nomenclature for clonal lineages of the sudden oak death pathogen, Phytophthora ramorum

Abstract: Phytophthora ramorum, the causal agent of sudden oak death and ramorum blight, is known to exist as three distinct clonal lineages which can only be distinguished by performing molecular marker-based analyses. However, in the recent literature there exists no consensus on naming of these lineages. Here we propose a system for naming clonal lineages of P. ramorum based on a consensus established by the P. ramorum research community. Clonal lineages are named with a two letter identifier for the continent on which they were first found (e.g., NA = North America; EU = Europe) followed by a number indicating order of appearance. Clonal lineages known to date are designated NA1 (mating type: A2; distribution: North America; environment: forest and nurseries), NA2 (A2; North America; nurseries), and EU1 (predominantly A1, rarely A2; Europe and North America; nurseries and gardens). It is expected that novel lineages or new variants within the existing three clonal lineages could in time emerge.

Effects of stand age, richness and density on productivity in subtropical forests in China

Abstract: Forest productivity may be determined not only by biodiversity but also by environmental factors and stand structure attributes. However, the relative importance of these factors in determining productivity is still controversial for subtropical forests. Based on a large dataset from 600 permanent forest inventory plots across subtropical China, we examined the relationship between biodiversity and forest productivity and tested whether stand structural attributes (stand density in terms of trees per ha, age and tree size) and environmental factors (climate and site conditions) had larger effects on productivity. Furthermore, we quantified the relative importance of environmental factors, stand structure and diversity in determining forest productivity. Diversity, together with stand structure and site conditions, regulated the variability in forest productivity. The relationship between diversity and forest productivity did not vary along environmental gradients. Stand density and age were more important modulators of forest productivity than diversity. Synthesis. Diversity had significant and positive effects on productivity in species‐rich subtropical forests, but the effects of stand density and age were also important. Our work highlights that while biodiversity conservation is often important, the regulation of stand structure can be even more important to maintain high productivity in subtropical forests.

Measurement of atmospheric deposition under forest canopies: some recommendations for equipment and sampling design

Abstract: Quantification of the forest water flux provides valuable information for the understanding of forest ecosystem functioning. As such, throughfall (and stemflow to a lesser extent) has been frequently measured. Although throughfall collection may seem relatively simple, the requirements to obtain reliable estimates are often underestimated. This review addresses the criteria to take into account when working out the sampling procedure, from the selection of equipment to implementation in the field. Sound sampling of the forest water flux is difficult due to its high spatial and temporal variation. The high costs entailed by the ideal sampling design often prohibit its implementation. Different procedures are available, some of which are compromises between the aim of the study (monitoring or experimental study, short or long term objectives, absolute or relative estimates, quality of the assessment to be achieved) and the available means.

Linking variability in soil solution dissolved organic carbon to climate, soil type, and vegetation type

Abstract: Lateral transport of carbon plays an important role in linking the carbon cycles of terrestrial and aquatic ecosystems. There is, however, a lack of information on the factors controlling one of the main C sources of this lateral flux, i.e., the concentration of dissolved organic carbon (DOC) in soil solution across large spatial scales and under different soil, vegetation, and climate conditions. We compiled a database on DOC in soil solution down to 80 cm and analyzed it with the aim, first, to quantify the differences in DOC concentrations among terrestrial ecosystems, climate zones, soil, and vegetation types at global scale and second, to identify potential determinants of the site-to-site variability of DOC concentration in soil solution across European broadleaved and coniferous forests. We found that DOC concentrations were 75% lower in mineral than in organic soil, and temperate sites showed higher DOC concentrations than boreal and tropical sites. The majority of the variation (R2 = 0.67–0.99) in DOC concentrations in mineral European forest soils correlates with NH4+, C/N, Al, and Fe as the most important predictors. Overall, our results show that the magnitude (23% lower in broadleaved than in coniferous forests) and the controlling factors of DOC in soil solution differ between forest types, with site productivity being more important in broadleaved forests and water balance in coniferous stands.