Yearly variation in allelopathic compound production along a climatic gradient. A case of study of Empetrum nigrum

Empetrum nigrum is a plant common in northern ecosystems with capacity to produce allelopathic compounds, which among other effects inhibit seed establishment and germination of other plants. Some of the most studied compounds regarding this effect are batatasin-III and phenolic acids, among them caffeic acid, which account for a large proportion of the leaf’s biomass. 5 random sites were established following a climatic gradient, and first year shoots were collected during 7 years. The plant’s antioxidant effect was studied as proxy of allelopathy, and shoot length was measured for the possible trade-offs between production of secondary metabolites and growth. The effect of climatic variables on the production of batatasin-III and caffeic acid was assessed, and the plant’s antioxidant activity and shoot growth were studied in accordance to the metabolite production and the weather conditions. Plants had higher concentration of batatasin-III in sites with low temperature, high number of freezing days during winter or both. Nevertheless, a positive relation between temperature and production of batatasin-III was found at the site level. Caffeic acid and antioxidant activity were positively related, however neither the weather variables studied explained their pattern. Shoot length was related to the year air temperature, but not to the production of batatasin-III or caffeic acid. In conclusion, this study shows that an increase of yearly temperature is likely to lead to an increase in batatasin-III production at the site level, but that no effect would happen to the growth of first year shoots. We were not able to find any impact of weather conditions on concentration of caffeic acid and on antioxidant activity

Natural variation in snow depth and snow melt timing in the High Arctic have implications for soil and plant nutrient status and vegetation composition

Snow cover is a key component in Arctic ecosystems and will likely be affected by changes in winter precipitation. Increased snow depth and consequent later snowmelt leads to greater microbial mineralization in winter, improving soil and vegetation nutrient status. We studied areas with naturally differing snow depths and date of snowmelt in Adventdalen, Svalbard. Soil properties, plant leaf nutrient status, and species composition along with the normalized difference vegetation index (NDVI) were compared for three snowmelt regimes (Early, Mid, and Late). We showed that (1) Late regimes (snow beds) had wetter soils, higher pH, and leaves of Bistorta vivipara (L.) Delarbre and Salix polaris Wahlenb. had higher concentration of nutrients (nitrogen and δ15N). Little to no difference was found in soil nutrient concentrations between snowmelt regimes. (2) Late regimes had highest NDVI values, whereas those of Early and Mid regimes were similar. (3) Vegetation composition differed between Early and Late regimes, with Dryas octopetala L. and Luzula arcuata subsp. confusa (Lange) characterizing the former and Equisetum arvense L. and Eriophorum scheuchzeri Hoppe the latter. (4) Trends for plant nutrient contents were similar to those found in a nearby snow manipulation experiment. Snow distribution and time of snowmelt played an important role in determining regional environmental heterogeneity, patchiness in plant community distribution, their species composition, and plant phenology

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.publishedVersio

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

Yearly variation in allelopathic compound production along a climatic gradient. A case of study of Empetrum nigrum

Empetrum nigrum is a plant common in northern ecosystems with capacity to produce allelopathic compounds, which among other effects inhibit seed establishment and germination of other plants. Some of the most studied compounds regarding this effect are batatasin-III and phenolic acids, among them caffeic acid, which account for a large proportion of the leaf’s biomass. 5 random sites were established following a climatic gradient, and first year shoots were collected during 7 years. The plant’s antioxidant effect was studied as proxy of allelopathy, and shoot length was measured for the possible trade-offs between production of secondary metabolites and growth. The effect of climatic variables on the production of batatasin-III and caffeic acid was assessed, and the plant’s antioxidant activity and shoot growth were studied in accordance to the metabolite production and the weather conditions. Plants had higher concentration of batatasin-III in sites with low temperature, high number of freezing days during winter or both. Nevertheless, a positive relation between temperature and production of batatasin-III was found at the site level. Caffeic acid and antioxidant activity were positively related, however neither the weather variables studied explained their pattern. Shoot length was related to the year air temperature, but not to the production of batatasin-III or caffeic acid. In conclusion, this study shows that an increase of yearly temperature is likely to lead to an increase in batatasin-III production at the site level, but that no effect would happen to the growth of first year shoots. We were not able to find any impact of weather conditions on concentration of caffeic acid and on antioxidant activity

High resistance to climatic variability in a dominant tundra shrub species

Climate change is modifying temperature and precipitation regimes across all seasons in northern ecosystems. Summer temperatures are higher, growing seasons extend into spring and fall and snow cover conditions are more variable during winter. The resistance of dominant tundra species to these season-specific changes, with each season potentially having contrasting effects on their growth and survival, can determine the future of tundra plant communities under climate change. In our study, we evaluated the effects of several spring/summer and winter climatic variables (i.e., summer temperature, growing season length, growing degree days, and number of winter freezing days) on the resistance of the dwarf shrub Empetrum nigrum. We measured over six years the ability of E. nigrum to keep a stable shoot growth, berry production, and vegetative cover in five E. nigrum dominated tundra heathlands, in a total of 144 plots covering a 200-km gradient from oceanic to continental climate. Overall, E. nigrum displayed high resistance to climatic variation along the gradient, with positive growth and reproductive output during all years and sites. Climatic conditions varied sharply among sites, especially during the winter months, finding that exposure to freezing temperatures during winter was correlated with reduced shoot length and berry production. These negative effects however, could be compensated if the following growing season was warm and long. Our study demonstrates that E. nigrum is a species resistant to fluctuating climatic conditions during the growing season and winter months in both oceanic and continental areas. Overall, E. nigrum appeared frost hardy and its resistance was determined by interactions among different season-specific climatic conditions with contrasting effects

High resistance to climatic variability in a dominant tundra shrub species

Climate change is modifying temperature and precipitation regimes across all seasons in northern ecosystems. Summer temperatures are higher, growing seasons extend into spring and fall and snow cover conditions are more variable during winter. The resistance of dominant tundra species to these season-specific changes, with each season potentially having contrasting effects on their growth and survival, can determine the future of tundra plant communities under climate change. In our study, we evaluated the effects of several spring/summer and winter climatic variables (i.e., summer temperature, growing season length, growing degree days, and number of winter freezing days) on the resistance of the dwarf shrub Empetrum nigrum. We measured over six years the ability of E. nigrum to keep a stable shoot growth, berry production, and vegetative cover in five E. nigrum dominated tundra heathlands, in a total of 144 plots covering a 200-km gradient from oceanic to continental climate. Overall, E. nigrum displayed high resistance to climatic variation along the gradient, with positive growth and reproductive output during all years and sites. Climatic conditions varied sharply among sites, especially during the winter months, finding that exposure to freezing temperatures during winter was correlated with reduced shoot length and berry production. These negative effects however, could be compensated if the following growing season was warm and long. Our study demonstrates that E. nigrum is a species resistant to fluctuating climatic conditions during the growing season and winter months in both oceanic and continental areas. Overall, E. nigrum appeared frost hardy and its resistance was determined by interactions among different season-specific climatic conditions with contrasting effects