TRY plant trait database – enhanced coverage and open access

Plant traits—the morphological, anatomical, physiological, biochemical and phenological characteristics of plants—determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait‐based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits—almost complete coverage for ‘plant growth form’. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait–environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives

Influence of stand age on the magnitude and seasonality of carbon fluxes in Canadian forests

Proper management and accounting of forest carbon requires good knowledge of how disturbances and climate affect the carbon dynamics of different stand types. We have investigated such relationships by measuring, over a 5-year period (2003–2007), the net ecosystem productivity (NEP), gross ecosystem productivity (GEP) and ecosystem respiration (ER) of 26 forest sites in Canada using the eddy covariance technique. The study included black spruce, jack pine, Douglas-fir, aspen, boreal mixedwood and white pine forest ecosystems ranging in age from 1- to 153-years. The dataset included six chronosequences (one afforested plantation, three harvested and two burned).Following planting, the afforested white pine stands quickly became carbon sinks and offset initial carbon losses after 4 years. Depending on forest type, the other forest stands were carbon sources for 10–18 years following a disturbance, offset initial carbon losses after 19–47 years, and showed net total gains ranging from 38 to 86 Mg C ha−1 at 80 years. Peak NEP ranged from 0.9 to 2.9 Mg C ha−1 year−1 at ages of 35–55 years except for the afforested white pine where it was 6.9 Mg C ha−1 year−1 at 15–20 years. Stepwise regression and Pearson correlation analyses indicated that the GEP and ER of mature stands (>70 years old) were driven mainly by climate, while fluxes of young stands (<19 years old) were driven by both leaf area index and climate.Although stand age of the afforested white pine plantations did not affect the GEP growing season lengths, the growing season length of the other forests increased with age until about 20 years and this coincided with the switch from carbon source to sink. With the exception of the afforested white pine, peak GEP/ER ratios of the youngest sites occurred later in the growing season compared to older sites. The strong influence of stand age on the seasonal dynamics of GEP fluxes needs to be considered to avoid confounding the impacts of climate change with those of disturbance. These age-related seasonality effects are continental in scope and should be important in interpreting the time series of atmospheric CO2 concentration measurements at regional and global scales

Influence of stand age on the magnitude and seasonality of carbon fluxes in Canadian forests

Proper management and accounting of forest carbon requires good knowledge of how disturbances and climate affect the carbon dynamics of different stand types. We have investigated such relationships by measuring, over a 5-year period (2003–2007), the net ecosystem productivity (NEP), gross ecosystem productivity (GEP) and ecosystem respiration (ER) of 26 forest sites in Canada using the eddy covariance technique. The study included black spruce, jack pine, Douglas-fir, aspen, boreal mixedwood and white pine forest ecosystems ranging in age from 1- to 153-years. The dataset included six chronosequences (one afforested plantation, three harvested and two burned).Following planting, the afforested white pine stands quickly became carbon sinks and offset initial carbon losses after 4 years. Depending on forest type, the other forest stands were carbon sources for 10–18 years following a disturbance, offset initial carbon losses after 19–47 years, and showed net total gains ranging from 38 to 86 Mg C ha−1 at 80 years. Peak NEP ranged from 0.9 to 2.9 Mg C ha−1 year−1 at ages of 35–55 years except for the afforested white pine where it was 6.9 Mg C ha−1 year−1 at 15–20 years. Stepwise regression and Pearson correlation analyses indicated that the GEP and ER of mature stands (>70 years old) were driven mainly by climate, while fluxes of young stands (<19 years old) were driven by both leaf area index and climate.Although stand age of the afforested white pine plantations did not affect the GEP growing season lengths, the growing season length of the other forests increased with age until about 20 years and this coincided with the switch from carbon source to sink. With the exception of the afforested white pine, peak GEP/ER ratios of the youngest sites occurred later in the growing season compared to older sites. The strong influence of stand age on the seasonal dynamics of GEP fluxes needs to be considered to avoid confounding the impacts of climate change with those of disturbance. These age-related seasonality effects are continental in scope and should be important in interpreting the time series of atmospheric CO2 concentration measurements at regional and global scales

Time-resolved fluorescence polarization anisotropy of multimodal samples: the asphaltene case

In this work we describe an application of the timeresolved fluorescence polarization anisotropy (TRFPA) technique to the analysis of asphaltenes, complex mixtures of highmolecular weight compounds, typically present in petroleum oils. Our asphaltene samples consist of nanometer-sized polydispersed particles, whose lighter fraction showed a relatively high fluorescence quantum yield. Most of the fluorescence intensity observed from the complex sample originated from a well defined sample fraction presenting a large fluorescence yield. Consequently, the TRFPA analysis only provided the average size of more fluorescing particles, that, in our case, were the smaller ones. Larger and less fluorescing aggregates did not significantly contribute to the TRFPA signal. Hence, to overcome intrinsic limitations of the TRFPA technique in characterizing multimodal samples, we preliminarily fractionated our complex samples by means of size exclusion chromatography (SEC), thus obtaining nearly monomodal fractions of the original samples. This procedure allowed to estimate also the size of less fluorescing and larger particles. A comparison of particle size estimate by means of TRFPA and SEC methods was also used to acquire information about occurrence of aggregation phenomena, and about the kind and strength of the chemical bonds linking chromophores to each other or to their parent particle

Impacts of Vegetation on the Decoupling between Air and Soil Temperatures across the Arctic

A rise in global air temperatures is expected to increase permafrost thaw and alter ecosystem carbon and water cycles in Arctic regions. The coupling between the soil temperature in the active layer (soil between the ground surface and permafrost) and air temperature is a key component in understanding permafrost stability and ecosystem change. Vegetation can affect soil temperature through a variety of mechanisms such as canopy shading, impacts on soil thermal conductivity via soil organic inputs or soil water uptake, albedo, and winter snow trapping. However, the relative importance of the vegetative effects on soil temperature is uncertain across large spatial scales and across different vegetative communities and ecosystem types. We compiled data on a Pan-Arctic scale pairing air and soil temperature with vegetation and ecosystem data to examine the impacts of vegetation on the decoupling of air and soil temperatures. We analyzed the summer thawing degree days, winter freezing degree days, and n factors (degree days soil/degree days air) from sites across the Arctic. Our results indicate that the decoupling between summer air and soil temperatures is more variable in boreal ecosystems than tundra ecosystems, and boreal ecosystems have lower winter n-factors than tundra ecosystems. Summer n-factors were more variable than winter n-factors, and had high variability within study sites. Vegetative and ecosystem characteristics can be key drivers of spatial and temporal variability in active layer soil temperature, particularly during the summer. Quantifying the impacts of vegetation on active layer temperature is critical to understanding how changes in vegetation under climate change can further affect permafrost stability and soil temperature

Antifungal Activity against Candida Biofilms

Candida species have two distinct lifestyles: planktonic, and surface-attached communities called biofilms. Mature C. albicans biofilms show a complex three-dimensional architecture with extensive spatial heterogeneity, and consist of a dense network of yeast, hyphae, and pseudohyphae encased within a matrix of exopolymeric material. Several key processes are likely to play vital roles at the dif- ferent stages of biofilm development, such as cell-substrate and cell-cell adherence, hyphal devel- opment, and quorum sensing. Biofilm formation is a survival strategy, since biofilm yeasts are more resistant to antifungals and environmental stress. Antifungal resistance is a multifactorial process that includes multidrug efflux pumps, target proteins of the ergosterol biosynthetic pathway. Most studies agree in presenting azoles as agents with poor activity against Candida spp. biofilms. However, recent studies have demonstrated that echinocandins and amphotericin B exhibit remarkable activity against C. albicans and Candida non-albicans biofilms. The association of Candida species with biofilm for- mation increases the therapeutic complexity of foreign body-related yeast infections. The traditional approach to the management of these infections has been to explant the affected device. There is a strong medical but also economical motivation for the development of novel anti-fungal biofilm strate- gies due to the constantly increasing resistance of Candida biofilms to conventional antifungals, and the high mortality caused by related infections. A better description of the extent and role of yeast in biofilms may be critical for developing novel therapeutic strategies in the clinical setting