Current analyses and predictions of spatially explicit patterns and processes in ecology most often rely on climate data interpolated from standardized weather stations. This interpolated climate data represents long-term average thermal conditions at coarse spatial resolutions only. Hence, many climate-forcing factors that operate at fine spatiotemporal resolutions are overlooked. This is particularly important in relation to effects of observation height (e.g. vegetation, snow and soil characteristics) and in habitats varying in their exposure to radiation, moisture and wind (e.g. topography, radiative forcing or cold-air pooling). Since organisms living close to the ground relate more strongly to these microclimatic conditions than to free-air temperatures, microclimatic ground and near-surface data are needed to provide realistic forecasts of the fate of such organisms under anthropogenic climate change, as well as of the functioning of the ecosystems they live in. To fill this critical gap, we highlight a call for temperature time series submissions to SoilTemp, a geospatial database initiative compiling soil and near-surface temperature data from all over the world. Currently, this database contains time series from 7,538 temperature sensors from 51 countries

Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids thus fail to reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions are controlled and most terrestrial species reside. Here we provide global maps of soil temperature and bioclimatic variables at a 1-km² resolution for 0-5 and 5-15 cm depth. These maps were created by calculating the difference (i.e., offset) between in-situ soil temperature measurements, based on time series from over 1200 1-km² pixels (summarized from 8500 unique temperature sensors) across all of the world's major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding 2 m gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (3.6 ± 2.3°C warmer than gridded air temperature), whereas soils in warm and humid environments are on average slightly cooler (0.7 ± 2.3°C cooler). The observed substantial and biome-specific offsets underpin that the projected impacts of climate and climate change on biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining global gaps by collecting more in-situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications.

-An intensive bark beetle outbreak occurred in [1993][1994][1995][1996][1997][1998] in the Tatra mountains between Slovakia and Poland. In the Slovak part of the outbreak practices consisted of: no action prior to 1994, intensive pest control management (trap trees, insecticides, salvage cutting) from 1995-1996, active differentiated approach (control measures according to the zonation of attacked stands) combined with intensive use of pheromone traps from 1997-1998. In Poland, the outbreak was mostly located in reserve areas where pest management or other activities were prohibited. Despite the use of intensive pest management measures, tree mortality was not significantly decreased in the Slovak region during the peak outbreak years of 1995 and 1996. Classical forest protection led to an increase in attractiveness of forest edges to bark beetles which could disperse to these areas from locations where no control measures were practiced. Unfavourable weather for bark beetles led to a rapid decrease in tree mortality in both parts of the study area. Picea abies / Ips typographus / outbreak / pest management / mountainsRésumé -Effets de différentes (active vs. passive) stratégies de gestion forestière des pullulations d'Ips typographus (L.) (Col.: Curculionidae, Scolytinae) dans les montagnes de Tatra en Pologne et Slovaquie. Une pullulation massive de scolytes s'est déroulée entre 1993 et 1998 dans les montagnes Tatras, situées entre la Pologne et la Slovaquie. Dans la partie Slovaque de la surface attaquée, la pratique forestière a consisté à ne pas intervenir jusqu'en 1994, puis en une protection active via l'utilisation d'arbres-pièges, d'insecticides et de coupes sanitaires entre 1995 et 1996, et en diverses techniques de lutte diversifiées selon la zonation des surfaces attaqués, combinées à l'utilisation de piégeages à phéromones en 1997 et 1998. En Pologne la pullulation était localiseé en grande majorité dans des réserves strictes où aucune mesure de protection n'était autorisée. Malgré l'importance des moyens de lutte mis en oeuvre, la mortalité des arbres n'a pas diminué significativement dans la partie Slovaque pendant les années 1995-1996. Les techniques utilisées aboutissaient à l'augmentation de l'attractivité des bordures de la forêt pour les scolytes, et ceux-ci pouvaient s'y développer en provenance de zones forestières ou le même niveau de contrôle n'était pas appliqué. Un climat défavorable au développement des scolytes a largement contribué à la diminution rapide des mortalités d'arbres observées dans les deux parties de la région étudiée.Picea abies / Ips typographus / pullulation / protection de la forêt / montagnes

Research in environmental science relies heavily on global climatic grids derived from estimates of air temperature at around 2 meter above ground1-3. These climatic grids however fail to reflect conditions near and below the soil surface, where critical ecosystem functions such as soil carbon storage are controlled and most biodiversity resides4-8. By using soil temperature time series from over 8500 locations across all of the world’s terrestrial biomes4, we derived global maps of soil temperature-related variables at 1 km resolution for the 0–5 and 5–15 cm depth horizons. Based on these maps, we show that mean annual soil temperature differs markedly from the corresponding 2 m gridded air temperature, by up to 10°C, with substantial variation across biomes and seasons. Soils in cold and/or dry biomes are annually substantially warmer (3.6°C ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are slightly cooler (0.7 ± 2.3°C). As a result, annual soil temperature varies less (by 17%) across the globe than air temperature. The effect of macroclimatic conditions on the difference between soil and air temperature highlights the importance of considering that macroclimate warming may not result in the same level of soil temperature warming. Similarly, changes in precipitation could alter the relationship between soil and air temperature, with implications for soil-atmosphere feedbacks9. Our results underpin that the impacts of climate and climate change on biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments.

Heatwaves exert disproportionately strong and sometimes irreversible impacts on forest ecosystems. These impacts remain poorly understood at the tree and species level and across large spatial scales. Here, we investigate the effects of the record-breaking 2018 European heatwave on tree growth and tree water status using a collection of high-temporal resolution dendrometer data from 21 species across 53 sites. Relative to the two preceding years, annual stem growth was not consistently reduced by the 2018 heatwave but stems experienced twice the temporary shrinkage due to depletion of water reserves. Conifer species were less capable of rehydrating overnight than broadleaves across gradients of soil and atmospheric drought, suggesting less resilience toward transient stress. In particular, Norway spruce and Scots pine experienced extensive stem dehydration. Our high-resolution dendrometer network was suitable to disentangle the effects of a severe heatwave on tree growth and desiccation at large-spatial scales in situ, and provided insights on which species may be more vulnerable to climate extremes.