• Energy Research
• 2021-2025close

Le pâturage représente l'utilisation la plus étendue des terres dans le monde. Pourtant, ses impacts sur les services écosystémiques restent incertains car des interactions omniprésentes entre la pression de pâturage, le climat, les propriétés des sols et la biodiversité peuvent se produire mais n'ont jamais été traitées simultanément. En utilisant une enquête standardisée sur 98 sites sur six continents, nous montrons que les interactions entre la pression du pâturage, le climat, le sol et la biodiversité sont essentielles pour expliquer la fourniture de services écosystémiques fondamentaux dans les zones arides du monde entier. L'augmentation de la pression de pâturage a réduit la prestation de services écosystémiques dans les zones arides plus chaudes et pauvres en espèces, tandis que les effets positifs du pâturage ont été observés dans les zones plus froides et riches en espèces. La prise en compte des interactions entre le pâturage et les facteurs abiotiques et biotiques locaux est essentielle pour comprendre le sort des écosystèmes des terres arides sous le changement climatique et l'augmentation de la pression humaine. El pastoreo representa el uso más extenso de la tierra en todo el mundo. Sin embargo, sus impactos en los servicios ecosistémicos siguen siendo inciertos porque las interacciones generalizadas entre la presión del pastoreo, el clima, las propiedades del suelo y la biodiversidad pueden ocurrir, pero nunca se han abordado simultáneamente. Utilizando una encuesta estandarizada en 98 sitios en seis continentes, mostramos que las interacciones entre la presión del pastoreo, el clima, el suelo y la biodiversidad son fundamentales para explicar la prestación de servicios ecosistémicos fundamentales en las tierras secas de todo el mundo. El aumento de la presión del pastoreo redujo la prestación de servicios ecosistémicos en las tierras secas más cálidas y pobres en especies, mientras que los efectos positivos del pastoreo se observaron en las zonas más frías y ricas en especies. Considerar las interacciones entre el pastoreo y los factores abióticos y bióticos locales es clave para comprender el destino de los ecosistemas de tierras secas bajo el cambio climático y el aumento de la presión humana. Grazing represents the most extensive use of land worldwide. Yet its impacts on ecosystem services remain uncertain because pervasive interactions between grazing pressure, climate, soil properties, and biodiversity may occur but have never been addressed simultaneously. Using a standardized survey at 98 sites across six continents, we show that interactions between grazing pressure, climate, soil, and biodiversity are critical to explain the delivery of fundamental ecosystem services across drylands worldwide. Increasing grazing pressure reduced ecosystem service delivery in warmer and species-poor drylands, whereas positive effects of grazing were observed in colder and species-rich areas. Considering interactions between grazing and local abiotic and biotic factors is key for understanding the fate of dryland ecosystems under climate change and increasing human pressure. يمثل الرعي الاستخدام الأوسع للأراضي في جميع أنحاء العالم. ومع ذلك، لا تزال آثاره على خدمات النظام الإيكولوجي غير مؤكدة لأن التفاعلات المنتشرة بين ضغط الرعي والمناخ وخصائص التربة والتنوع البيولوجي قد تحدث ولكن لم تتم معالجتها أبدًا في وقت واحد. باستخدام مسح موحد في 98 موقعًا في ست قارات، نوضح أن التفاعلات بين ضغط الرعي والمناخ والتربة والتنوع البيولوجي ضرورية لشرح تقديم خدمات النظام الإيكولوجي الأساسية عبر الأراضي الجافة في جميع أنحاء العالم. أدى الضغط المتزايد للرعي إلى تقليل تقديم خدمات النظام الإيكولوجي في الأراضي الجافة الأكثر دفئًا والفقيرة بالأنواع، في حين لوحظت آثار إيجابية للرعي في المناطق الأكثر برودة والغنية بالأنواع. يعتبر النظر في التفاعلات بين الرعي والعوامل المحلية اللاأحيائية والأحيائية أمرًا أساسيًا لفهم مصير النظم الإيكولوجية للأراضي الجافة في ظل تغير المناخ وزيادة الضغط البشري.

Le pâturage représente l'utilisation la plus étendue des terres dans le monde. Pourtant, ses impacts sur les services écosystémiques restent incertains car des interactions omniprésentes entre la pression de pâturage, le climat, les propriétés des sols et la biodiversité peuvent se produire mais n'ont jamais été traitées simultanément. En utilisant une enquête standardisée sur 98 sites sur six continents, nous montrons que les interactions entre la pression du pâturage, le climat, le sol et la biodiversité sont essentielles pour expliquer la fourniture de services écosystémiques fondamentaux dans les zones arides du monde entier. L'augmentation de la pression de pâturage a réduit la prestation de services écosystémiques dans les zones arides plus chaudes et pauvres en espèces, tandis que les effets positifs du pâturage ont été observés dans les zones plus froides et riches en espèces. La prise en compte des interactions entre le pâturage et les facteurs abiotiques et biotiques locaux est essentielle pour comprendre le sort des écosystèmes des terres arides sous le changement climatique et l'augmentation de la pression humaine. El pastoreo representa el uso más extenso de la tierra en todo el mundo. Sin embargo, sus impactos en los servicios ecosistémicos siguen siendo inciertos porque las interacciones generalizadas entre la presión del pastoreo, el clima, las propiedades del suelo y la biodiversidad pueden ocurrir, pero nunca se han abordado simultáneamente. Utilizando una encuesta estandarizada en 98 sitios en seis continentes, mostramos que las interacciones entre la presión del pastoreo, el clima, el suelo y la biodiversidad son fundamentales para explicar la prestación de servicios ecosistémicos fundamentales en las tierras secas de todo el mundo. El aumento de la presión del pastoreo redujo la prestación de servicios ecosistémicos en las tierras secas más cálidas y pobres en especies, mientras que los efectos positivos del pastoreo se observaron en las zonas más frías y ricas en especies. Considerar las interacciones entre el pastoreo y los factores abióticos y bióticos locales es clave para comprender el destino de los ecosistemas de tierras secas bajo el cambio climático y el aumento de la presión humana. Grazing represents the most extensive use of land worldwide. Yet its impacts on ecosystem services remain uncertain because pervasive interactions between grazing pressure, climate, soil properties, and biodiversity may occur but have never been addressed simultaneously. Using a standardized survey at 98 sites across six continents, we show that interactions between grazing pressure, climate, soil, and biodiversity are critical to explain the delivery of fundamental ecosystem services across drylands worldwide. Increasing grazing pressure reduced ecosystem service delivery in warmer and species-poor drylands, whereas positive effects of grazing were observed in colder and species-rich areas. Considering interactions between grazing and local abiotic and biotic factors is key for understanding the fate of dryland ecosystems under climate change and increasing human pressure. يمثل الرعي الاستخدام الأوسع للأراضي في جميع أنحاء العالم. ومع ذلك، لا تزال آثاره على خدمات النظام الإيكولوجي غير مؤكدة لأن التفاعلات المنتشرة بين ضغط الرعي والمناخ وخصائص التربة والتنوع البيولوجي قد تحدث ولكن لم تتم معالجتها أبدًا في وقت واحد. باستخدام مسح موحد في 98 موقعًا في ست قارات، نوضح أن التفاعلات بين ضغط الرعي والمناخ والتربة والتنوع البيولوجي ضرورية لشرح تقديم خدمات النظام الإيكولوجي الأساسية عبر الأراضي الجافة في جميع أنحاء العالم. أدى الضغط المتزايد للرعي إلى تقليل تقديم خدمات النظام الإيكولوجي في الأراضي الجافة الأكثر دفئًا والفقيرة بالأنواع، في حين لوحظت آثار إيجابية للرعي في المناطق الأكثر برودة والغنية بالأنواع. يعتبر النظر في التفاعلات بين الرعي والعوامل المحلية اللاأحيائية والأحيائية أمرًا أساسيًا لفهم مصير النظم الإيكولوجية للأراضي الجافة في ظل تغير المناخ وزيادة الضغط البشري.

AbstractAimFungi are major drivers of ecosystem functioning. Increases in aridity are known to negatively impact fungal community composition in dryland ecosystems globally; yet, much less is known on the potential influence of other environmental drivers, and whether these relationships are linear or nonlinear.Time period2017–2021.LocationGlobal.Major taxa studiedFungi.MethodsWe re‐analysed multiple datasets from different dryland biogeographical regions, for a total of 912 samples and 1,483 taxa. We examined geographical patterns in community diversity and composition, and spatial, edaphic and climatic factors driving them.ResultsUV index, climate seasonality, and sand content were the most important environmental predictors of community shifts, showing the strongest association with the richness of putative plant pathogens and saprobes. Important nonlinear relationships existed with each of these fungal guilds, with increases in UV and temperature seasonality above 7.5 and 900 SD (standard deviation x 100 of the mean monthly temperature), respectively, being associated with an increased probability of plant pathogen and unspecified saprotroph occurrence. Conversely, these environmental parameters had a negative relationship with litter and soil saprotroph richness. Consequently, these ecological groups might be particularly sensitive to shifts in UV radiation and climate seasonality, which is likely to disturb current plant–soil dynamics in drylands.Main conclusionsOur synthesis integrates fungal community data from drylands across the globe, allowing the investigation of fungal distribution and providing the first evidence of shifts in fungal diversity and composition of key fungal ecological groups along diverse spatial, climatic and edaphic gradients in these widely distributed ecosystems. Our findings imply that shifts in soil structure and seasonal climatic patterns induced by global change will have disproportionate consequences for the distribution of fungal groups linked to vegetation and biogeochemical cycling in drylands, with implications for plant–soil interactions in drylands.

AbstractAimFungi are major drivers of ecosystem functioning. Increases in aridity are known to negatively impact fungal community composition in dryland ecosystems globally; yet, much less is known on the potential influence of other environmental drivers, and whether these relationships are linear or nonlinear.Time period2017–2021.LocationGlobal.Major taxa studiedFungi.MethodsWe re‐analysed multiple datasets from different dryland biogeographical regions, for a total of 912 samples and 1,483 taxa. We examined geographical patterns in community diversity and composition, and spatial, edaphic and climatic factors driving them.ResultsUV index, climate seasonality, and sand content were the most important environmental predictors of community shifts, showing the strongest association with the richness of putative plant pathogens and saprobes. Important nonlinear relationships existed with each of these fungal guilds, with increases in UV and temperature seasonality above 7.5 and 900 SD (standard deviation x 100 of the mean monthly temperature), respectively, being associated with an increased probability of plant pathogen and unspecified saprotroph occurrence. Conversely, these environmental parameters had a negative relationship with litter and soil saprotroph richness. Consequently, these ecological groups might be particularly sensitive to shifts in UV radiation and climate seasonality, which is likely to disturb current plant–soil dynamics in drylands.Main conclusionsOur synthesis integrates fungal community data from drylands across the globe, allowing the investigation of fungal distribution and providing the first evidence of shifts in fungal diversity and composition of key fungal ecological groups along diverse spatial, climatic and edaphic gradients in these widely distributed ecosystems. Our findings imply that shifts in soil structure and seasonal climatic patterns induced by global change will have disproportionate consequences for the distribution of fungal groups linked to vegetation and biogeochemical cycling in drylands, with implications for plant–soil interactions in drylands.

Water availability controls the functioning of dryland ecosystems, driving a patchy vegetation distribution, unequal nutrient availability, soil respiration in pulses, and limited productivity. Groundwater-dependent ecosystems (GDEs) are acknowledged to be decoupled from precipitation, since their vegetation relies on groundwater sources. Despite their relevance to enhance productivity in drylands, our understanding of how different components of GDEs interconnect (i.e., soil, vegetation, water) remains limited. We studied the GDE dominated by the deep-rooted phreatophyte Ziziphus lotus, a winter-deciduous shrub adapted to arid conditions along the Mediterranean basin. We aimed to disentangle whether the groundwater connection established by Z. lotus will foster soil biological activity and therefore soil fertility in drylands. We assessed (1) soil and vegetation dynamics over seasons (soil CO2 efflux and plant activity), (2) the effect of the patchy distribution on soil quality (properties and nutrient availability), and soil biological activity (microbial biomass and mineralization rates) as essential elements of biogeochemical cycles, and (3) the implications for preserving GDEs and their biogeochemical processes under climate change effects. We found that soil and vegetation dynamics respond to water availability. Whereas soil biological activity promptly responded to precipitation events, vegetation functioning relies on less superficial water and responded on different time scales. Soil quality was higher under the vegetation patches, as was soil biological activity. Our findings highlight the importance of groundwater connections and phreatophytic vegetation to increase litter inputs and organic matter into the soils, which in turn enhances soil quality and decomposition processes in drylands. However, biogeochemical processes are jeopardized in GDEs by climate change effects and land degradation due to the dependence of soil activity on: (1) precipitation for activation, and (2) phreatophytic vegetation for substrate accumulation. Therefore, desertification might modify biogeochemical cycles by disrupting key ecosystem processes such as soil microbial activity, organic matter mineralization, and plant productivity.

Water availability controls the functioning of dryland ecosystems, driving a patchy vegetation distribution, unequal nutrient availability, soil respiration in pulses, and limited productivity. Groundwater-dependent ecosystems (GDEs) are acknowledged to be decoupled from precipitation, since their vegetation relies on groundwater sources. Despite their relevance to enhance productivity in drylands, our understanding of how different components of GDEs interconnect (i.e., soil, vegetation, water) remains limited. We studied the GDE dominated by the deep-rooted phreatophyte Ziziphus lotus, a winter-deciduous shrub adapted to arid conditions along the Mediterranean basin. We aimed to disentangle whether the groundwater connection established by Z. lotus will foster soil biological activity and therefore soil fertility in drylands. We assessed (1) soil and vegetation dynamics over seasons (soil CO2 efflux and plant activity), (2) the effect of the patchy distribution on soil quality (properties and nutrient availability), and soil biological activity (microbial biomass and mineralization rates) as essential elements of biogeochemical cycles, and (3) the implications for preserving GDEs and their biogeochemical processes under climate change effects. We found that soil and vegetation dynamics respond to water availability. Whereas soil biological activity promptly responded to precipitation events, vegetation functioning relies on less superficial water and responded on different time scales. Soil quality was higher under the vegetation patches, as was soil biological activity. Our findings highlight the importance of groundwater connections and phreatophytic vegetation to increase litter inputs and organic matter into the soils, which in turn enhances soil quality and decomposition processes in drylands. However, biogeochemical processes are jeopardized in GDEs by climate change effects and land degradation due to the dependence of soil activity on: (1) precipitation for activation, and (2) phreatophytic vegetation for substrate accumulation. Therefore, desertification might modify biogeochemical cycles by disrupting key ecosystem processes such as soil microbial activity, organic matter mineralization, and plant productivity.