Global maps of soil temperature

Abstract

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.

Temperature thresholds drive the global distribution of soil fungal decomposers

“…We also obtained soil temperature (land surface temperature) from https://neo.gsfc.nasa.gov, covering the period of study. Our choice of soil temperature was also positively and significantly correlated with a recent index of soil temperature (Lembrechts et al, 2021) ( r = .89; p < .001; n = 235). We fitted linear and non‐linear (quadratic and general additive models [GAM] (Hastie, 2020)) regressions to the relationships between these temperature variables and the proportion of soil fungal decomposers as well as soil carbon content separately.…”

Near-universal trends in brGDGT lipid distributions in nature

“…Furthermore, many commonly used measurements are themselves only proxies for the true environmental conditions experienced by brGDGT-producing microbes. For example, air temperature is commonly used in place of in situ soil temperature, although the annual means of the two can differ by as much as 10°C ( 72 ). As a result, it is not possible at this time to standardize environmental parameters, such that datasets of different sample types can be fully quantitatively merged.…”

How Could the Use of Crop Wild Relatives in Breeding Increase the Adaptation of Crops to Marginal Environments?

“…This approach does not require phenotypic experiments, thus allowing the evaluation in silico of hundreds to thousands of accessions. Several climatic databased, including WorldClim ( Fick and Hijmans, 2017 ), Envirem ( Title and Bemmels, 2018 ), and SoilTemp ( Lembrechts et al, 2021 ), along with genomic information can be used to link geographic coordinates of any accession with local environmental conditions and genomic data, increasing the value of ex situ collections. Recent examples focused on wild relatives of soybean ( Anderson et al, 2016 ), wheat ( Brunazzi et al, 2018 ), narrow-leafed lupin ( Mousavi-Derazmahalleh et al, 2018 ), and chickpea ( von Wettberg et al, 2018 ).…”