Global maps of soil temperature

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 do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur 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 soil 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 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 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) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (-0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface 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 geographic gaps by collecting more in-situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications

Global maps of soil temperature

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 do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur 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 soil 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 8519 unique temperature sensors) across all the world\u27s 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 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) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (−0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface 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 geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications

Global maps of soil temperature.

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 do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur 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 soil 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 8519 unique temperature sensors) across all 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 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) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (-0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface 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 geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications

Variation of oak wood properties influencing the maturation of whisky

Oak casks are used for the maturation of a wide variety of alcoholic beverages including Scotch whisky. The process of maturation has a profound but variable effect on the colour and flavour of the whisky, with cask wood playing an important role, particularly through the release of extractives to the distillate. This thesis examines variation in European oak wood (Quercus petraea Matt. Liebl. and Q. robur L.) of ellagitannins, oak lactones and other extractives, and physical wood properties. Investigations particularly sought to establish whether the properties and their effects on flavour can be predicted from either the species, the various forest origins, or identifiable wood or tree characters. The treatment of wood after felling, through seasoning and particularly the toasting or charring of casks, has a major effect on the levels of many extractives. Heating reduces the concentrations of ellagitannins and increases levels of lignin-derived extractives. However, the effects are not such as to render variation in untreated wood inconsequential. Within trees, the concentration of soluble ellagitannins declines and the composition changes with heartwood age. When heartwood of a similar age is compared concentrations vary by up to ten times between different trees, making up to 14% of the heartwood dry weight. Concentrations of oak lactones appear to increase with heartwood age and are also very variable between trees. Wood samples were taken from two different forests, corresponding to opposing types of French oak used for cooperage. Over 70% of the total variation of soluble tannins in the wood occurred between the forests. A difference between the two forests in the rate of tree growth and the heartwood age of samples could not explain all of the difference in the amounts of soluble tannins. After heating the wood, the concentrations of other extractives and the flavour and colour imparted to solutions, also varied significantly between the two forests and between trees within each site. Studies on clonal, progeny and provenance material concluded that the concentration of ellagitannins, oak lactones and many physical properties of heartwood are under strong genetic control. However, a large proportion of this variation is attributable to variation between the two species Q. robur and Q. petraea. Q. robur is characterised by high concentrations of tannins and, after heating, of lignin-derived products, but low or negligible levels of oak lactones. Q. petraea has opposing extractive properties and after heating, imparts a more pleasant and complex flavour. Although there is large variation between trees within each species, this difference between the species is proposed as the main factor explaining the different flavour and extractive properties found in European oak wood from different origins.</p

Variation of oak wood properties influencing the maturation of whisky

Oak casks are used for the maturation of a wide variety of alcoholic beverages including Scotch whisky. The process of maturation has a profound but variable effect on the colour and flavour of the whisky, with cask wood playing an important role, particularly through the release of extractives to the distillate. This thesis examines variation in European oak wood (Quercus petraea Matt. Liebl. and Q. robur L.) of ellagitannins, oak lactones and other extractives, and physical wood properties. Investigations particularly sought to establish whether the properties and their effects on flavour can be predicted from either the species, the various forest origins, or identifiable wood or tree characters. The treatment of wood after felling, through seasoning and particularly the toasting or charring of casks, has a major effect on the levels of many extractives. Heating reduces the concentrations of ellagitannins and increases levels of lignin-derived extractives. However, the effects are not such as to render variation in untreated wood inconsequential. Within trees, the concentration of soluble ellagitannins declines and the composition changes with heartwood age. When heartwood of a similar age is compared concentrations vary by up to ten times between different trees, making up to 14% of the heartwood dry weight. Concentrations of oak lactones appear to increase with heartwood age and are also very variable between trees. Wood samples were taken from two different forests, corresponding to opposing types of French oak used for cooperage. Over 70% of the total variation of soluble tannins in the wood occurred between the forests. A difference between the two forests in the rate of tree growth and the heartwood age of samples could not explain all of the difference in the amounts of soluble tannins. After heating the wood, the concentrations of other extractives and the flavour and colour imparted to solutions, also varied significantly between the two forests and between trees within each site. Studies on clonal, progeny and provenance material concluded that the concentration of ellagitannins, oak lactones and many physical properties of heartwood are under strong genetic control. However, a large proportion of this variation is attributable to variation between the two species Q. robur and Q. petraea. Q. robur is characterised by high concentrations of tannins and, after heating, of lignin-derived products, but low or negligible levels of oak lactones. Q. petraea has opposing extractive properties and after heating, imparts a more pleasant and complex flavour. Although there is large variation between trees within each species, this difference between the species is proposed as the main factor explaining the different flavour and extractive properties found in European oak wood from different origins.</p

Climate Change and Crop Exposure to Adverse Weather: Changes to Frost Risk and Grapevine Flowering Conditions

<div><p>The cultivation of grapevines in the UK and many other cool climate regions is expected to benefit from the higher growing season temperatures predicted under future climate scenarios. Yet the effects of climate change on the risk of adverse weather conditions or events at key stages of crop development are not always captured by aggregated measures of seasonal or yearly climates, or by downscaling techniques that assume climate variability will remain unchanged under future scenarios. Using fine resolution projections of future climate scenarios for south-west England and grapevine phenology models we explore how risks to cool-climate vineyard harvests vary under future climate conditions. Results indicate that the risk of adverse conditions during flowering declines under all future climate scenarios. In contrast, the risk of late spring frosts increases under many future climate projections due to advancement in the timing of budbreak. Estimates of frost risk, however, were highly sensitive to the choice of phenology model, and future frost exposure declined when budbreak was calculated using models that included a winter chill requirement for dormancy break. The lack of robust phenological models is a major source of uncertainty concerning the impacts of future climate change on the development of cool-climate viticulture in historically marginal climatic regions.</p></div

Mean budbreak and flowering times under different climate conditions using two types of phenology model: (i) spring warming budbreak and flowering models [58, 60, 62], and (ii) winter chilling (vernalization) models [53].

<p>Mean budbreak and flowering times under different climate conditions using two types of phenology model: (i) spring warming budbreak and flowering models [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0141218#pone.0141218.ref058" target="_blank">58</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0141218#pone.0141218.ref060" target="_blank">60</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0141218#pone.0141218.ref062" target="_blank">62</a>], and (ii) winter chilling (vernalization) models [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0141218#pone.0141218.ref053" target="_blank">53</a>].</p

Changes in cumulative growing season GDD (1^st April to 31^st October) calculated from baseline (1960–90) weather generator runs, daily historic weather data (1960–2011) and future climate weather generator runs using three emissions scenarios (low, middle and high emissions from left to right) and time periods.

<p>Baseline quantile box plots calculated from 9,000 30-year time sequences; future box plots from 1,000 30-year time sequences.</p

Mean seasonal growing degree days, measures of late frost risk and of adverse flowering weather under different climate scenarios.

<p>Late frost risk expressed as (i) probability of a frost day (minimum temperature < = 0°C) after budbreak; (ii) mean number of these frost days, and (iii) mean accumulated degree days under 2°C after budbreak. Adverse flowering weather defined as a mean daily temperature <15°C or total precipitation>5mm and expressed as (i) the probability of 10 or more adverse days during the 7 days before and after flowering, and (ii) mean number of adverse days during the same 15 day period. The timing of budbreak and flowering calculated using spring warming models.</p