DOI: 10.5061/dryad.qrfj6q5g8
title: Warm range margin of boreal bryophytes and lichens not directly limited by temperatures

description: 1. 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 e.g. competitive species, is still not fully resolved. 2. We examined
 whether boreal bryophytes and lichens show signs of direct climate
 limitation, i.e. 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 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 sub-canopy temperature, soil
 moisture, air humidity, and forest type. In 2018, we also recorded cover
 of other plants having re-colonized the garden soil patches and modelled
 this potential future competition with the same environmental variables
 plus litter. 3. 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 direct temperature for performance
 at the species’ warm range margin. 4. Synthesis. In a transplant
 experiment with three boreal understory species we did not find signs of
 direct temperature limitation towards the south. Forest microrefugia, i.e.
 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 overstory.
description: Three boreal species (a moss, a liverwort and a lichen) were
 transplanted to 58 sites with contrasting microclimate at their southern
 range margin. At each site, 3 plots were established with one individual
 cushion per species each. Transplanted species were measured right after
 transplantation and followed for 3 growing seasons. At
 each site, we recorded microclimate (temperature and humidity) with small
 sensors (iButtons), soil moisture, proportion of conifers and canopy
 cover. Details are found in the methods of the
 open-access article. Greiser et al. (2021) Warm range
 margin of boreal bryophytes and lichens not directly limited by
 temperatures. Journal of Ecology.
description: Provided are the data as they were fed into the models for
 growth, vitality and recolonization/competition.<br> Additionally,
 there is a csv-file with the coordinates of each transplant site
 (long/lat, WGS84). Abbreviations:
 Bar = Barbilophozia lycopodioides<br> Nep = Nephroma
 arcticum<br> Dic = Dicranum drummondii GDD =
 Growing Degree Days<br> VPDmax = maximum Vapour Pressure Deficit
 (growing season average of daily VPDmax) [kPa]<br> perccon =
 proportion of conifers [%]<br> canopy = canopy cover [%]<br>
 Tmin = minimum temperature (growing season average of daily
 Tmin)<br> soilmoist = soil moisture [vol%] growth
 = change in size from t to t+1.<br>         For Bar and Nep:
 square-root transformed proportional growth in area =
 sqrt(area.t+1/area.t)<br>         For Dic: absolute growth in height
 [mm] = height.t+1 - height.t vit = vitality, expressed
 as the (arcsine-square-root transformed) proportion of vital
 tissue comp = competition/recolonization, proportion of
 the plot that was covered with recolonizing vegetation at the end of the
 experiment<br>         the original values were divided by 100 and
 additionally transformed according to y = (y(n−1) + 0.5)/n  where n is the
 sample size (in order to range between 0 and 1) For
 more details, check the open-access publication.