Monthly microclimate models in a managed boreal forest landscape

The majority of microclimate studies have been done in topographically complex landscapes to quantify and predict how near-ground temperatures vary as a function of terrain properties. However, in forests understory temperatures can be strongly influenced also by vegetation. We quantified the relative influence of vegetation features and physiography (topography and moisture-related variables) on understory temperatures in managed boreal forests in central Sweden. We used a multivariate regression approach to relate near-ground temperature of 203 loggers over the snow-free seasons in an area of ∼16,000 km2 to remotely sensed and on-site measured variables of forest structure and physiography. We produced climate grids of monthly minimum and maximum temperatures at 25m resolution by using only remotely sensed and mapped predictors. The quality and predictions of the models containing only remotely sensed predictors (MAP models) were compared with the models containing also on-site measured predictors (OS models). Our data suggest that during the warm season, where landscape microclimate variability is largest, canopy cover and basal area were the most important microclimatic drivers for both minimum and maximum temperatures, while physiographic drivers (mainly elevation) dominated maximum temperatures during autumn and early winter. The MAP models were able to reproduce findings from the OS models but tended to underestimate high and overestimate low temperatures. Including important microclimatic drivers, particularly soil moisture, that are yet lacking in a mapped form should improve the microclimate maps. Because of the dynamic nature of managed forests, continuous updates of mapped forest structure parameters are needed to accurately predict temperatures. Our results suggest that forest management (e.g. stand size, structure and composition) and conservation may play a key role in amplifying or impeding the effects of climate-forcing factors on near-ground temperature and may locally modify the impact of global warming.Peer reviewe

Warm range margin of boreal bryophytes and lichens not directly limited by temperatures

Species at their warm range margin are potentially threatened by higher temperatures, but may persist in microrefugia. Whether such microsites occur due to more suitable microclimate or due to lower biotic pressure from, for example competitive species, is still not fully resolved. We examined whether boreal bryophytes and lichens show signs of direct climate limitation, that is whether they perform better in cold and/or humid microclimates at their warm range margin. We transplanted a moss, a liverwort and a lichen to 58 boreal forest sites with different microclimates at the species' southern range margin in central Sweden. Species were grown in garden soil patches to control the effects of competitive exclusion and soil quality. We followed the transplanted species over three growing seasons (2016-2018) and modelled growth and vitality for each species as a function of subcanopy temperature, soil moisture, air humidity and forest type. In 2018, we also recorded the cover of other plants having recolonized the garden soil patches and modelled this potential future competition with the same environmental variables plus litter. Species performance increased with warmer temperatures, which was often conditional on high soil moisture, and at sites with more conifers. Soil moisture had a positive effect, especially on the moss in the last year 2018, when the growing season was exceptionally hot and dry. The lichen was mostly affected by gastropod grazing. Recolonization of other plants was also faster at warmer and moister sites. The results indicate that competition, herbivory, shading leaf litter and water scarcity might be more important than the direct effects of temperature for performance at the species' warm range margin. Synthesis. In a transplant experiment with three boreal understorey species, we did not find signs of direct temperature limitation towards the south. Forest microrefugia, that is habitats where these species could persist regional warming, may instead be sites with fewer competitors and enemies, and with sufficient moisture and more conifers in the overstorey.Peer reviewe

Strong microsite control of seedling recruitment in tundra

The inclusion of environmental variation in studies of recruitment is a prerequisite for realistic predictions of the responses of vegetation to a changing environment. We investigated how seedling recruitment is affected by seed availability and microsite quality along a steep environmental gradient in dry tundra. A survey of natural seed rain and seedling density in vegetation was combined with observations of the establishment of 14 species after sowing into intact or disturbed vegetation. Although seed rain density was closely correlated with natural seedling establishment, the experimental seed addition showed that the microsite environment was even more important. For all species, seedling emergence peaked at the productive end of the gradient, irrespective of the adult niches realized. Disturbance promoted recruitment at all positions along the environmental gradient, not just at high productivity. Early seedling emergence constituted the main temporal bottleneck in recruitment for all species. Surprisingly, winter mortality was highest at what appeared to be the most benign end of the gradient. The results highlight that seedling recruitment patterns are largely determined by the earliest stages in seedling emergence, which again are closely linked to microsite quality. A fuller understanding of microsite effects on recruitment with implications for plant community assembly and vegetation change is provided

Analysis of shared common genetic risk between amyotrophic lateral sclerosis and epilepsy

Because hyper-excitability has been shown to be a shared pathophysiological mechanism, we used the latest and largest genome-wide studies in amyotrophic lateral sclerosis (n = 36,052) and epilepsy (n = 38,349) to determine genetic overlap between these conditions. First, we showed no significant genetic correlation, also when binned on minor allele frequency. Second, we confirmed the absence of polygenic overlap using genomic risk score analysis. Finally, we did not identify pleiotropic variants in meta-analyses of the 2 diseases. Our findings indicate that amyotrophic lateral sclerosis and epilepsy do not share common genetic risk, showing that hyper-excitability in both disorders has distinct origins

Assessing and comparing climatic control on distribution and reproduction of alpine and lowland species in the subalpine habitat of western Norway.

Aims and background: Species range shift is among the most well-documented responses to climate change. As a result, a growing number of studies model species climatic niches to predict how species ranges may displace in space and time (SDM studies). These studies are criticised because they do not include reproduction in their predictions. Other studies use empirical data to assess climatic control on reproductive life-stages. However, the climatic niche of reproductive life-stages may not determine the climatic niche of species, limiting the ability of both types of studies to assess the effect of climate change. In this synthesis, I compare the results of a SDM study (Paper I) with the results of two empirical studies focussing on flowering performance (Paper II) and seedling emergence (Paper III). The research focuses on the leading and rear altitudinal edges of lowland and alpine species ranges, respectively, as those are the two delimiting fronts that are expected to be specifically vulnerable to climate change. Reproduction response to climate is a complex process because it involves several sub-stages that can be affected by climate in several ways. Therefore, the results included in this synthesis integrate several direct and size-dependent climatic effects on flowering performance and report on the importance of both the climate conditions occurring at the recruitment sites and those experienced by the source populations for seedling emergence. Study area and species: This thesis makes use of the sub-alpine and alpine landscapes of western Norway to investigate climatic control on species occurrence and reproduction. This study area was chosen because it includes the leading altitudinal edge of lowland species’ ranges and the rear altitudinal edge of alpine species’ ranges. The research uses Viola biflora (alpine), Viola palustris (lowland), Veronica alpina (alpine), and Veronica officinalis (lowland) as study cases because these species are common in the study area and the study sites, and are representative of the alpine and lowland communities occurring at the studied sites. Results and discussion: The climatic control on flowering performances and seedling emergence did not reflect the climatic niches of three out of four species, suggesting ontogenetic niche shift. These mismatches challenge the predictive ability of both SDMs and empirical studies focusing on reproductive life-stages. Papers II and III highlight the complexity of climatic control on reproduction and show species-specific results. Flowering was both climate- and size-dependent for three species, but the way size-dependency was expressed differed between species. Seedling emergence was less species-specific although one species (Veronica officinalis) was found to be affected by the climate experienced by its source populations while the three other species were only responding to the climate of their sowing sites. This illustrates the importance of accounting for the complexity of reproduction to improve climate-change predictions on plant reproduction. Finally, Papers I and II suggest a high importance of biotic interactions from the lowland flora for the two alpine species, stressing the importance of understanding plant-plant interactions to forecast climate-change impacts. Further research and conclusions: Structured population models can resolve some of the problems reported in this synthesis but further methodological developments are necessary to integrate local adaptation patterns and to accurately project the outputs of such models in space. Dispersal has been largely ignored in climate-change studies. Further research should also aim to improve knowledge on dispersal because quantifying dispersal and recruitment rates is required to predict accurately climate-change impacts on plant populations and potential range displacements. Individualistic responses to climate suggest drastic changes in plant communities over the coming years. Given the high importance of biotic interactions, increasing knowledge on species interactions will be an important step to better understand and predict the potential climate-change impacts. Since the climatic control of a given species may not relate to the climatic control of another species, more effort should be given to key and/or endangered species that may have specific value for conservation

Climate grids_GEOTIFF

High resolution (50 m) raster maps (format GEOTIFF) of 15 climate variables over Sweden for the time period 2000-201

Climate grids_R format

High resolution (50 m) raster maps (format: R multi-layer grid) of 15 climate variables over Sweden for the time period 2000-201

Modélisation de la répartition de la consoude bulbeuse (Symphytum bulbosum Schimp.) en vue de sa conservation dans les Alpes-Maritimes et le Var

CITATIONS 0 READS 33 4 authors: Some of the authors of this publication are also working on these related projects: Microrefugia and stepping stones-the role of microclimate in climate-driven range shifts View project Conservation of the rare and endangered flora of french Mediterranean basin View project Maëlle Le Berre Conservatoire botanique national méditerranéen de Porquerolle