Aridity modulates grassland biomass responses to combined drought and nutrient addition

Abstract

Plant biomass tends to increase under nutrient addition and decrease under drought. Biotic and abiotic factors influence responses to both, making the combined impact of nutrient addition and drought difficult to predict. Using a globally distributed network of manipulative field experiments, we assessed grassland aboveground biomass response to both drought and increased nutrient availability at 26 sites across nine countries. Overall, drought reduced biomass by 19% and nutrient addition increased it by 24%, resulting in no net impact under combined drought and nutrient addition. Among the plant functional groups, only graminoids responded positively to nutrients during drought. However, these general responses depended on local conditions, especially aridity. Nutrient effects were stronger in arid grasslands and weaker in humid regions and nitrogen-rich soils, although nutrient addition alleviated drought effects the most in subhumid sites. Biomass responses were weaker with higher precipitation variability. Biomass increased more with increased nutrient availability and declined more with drought at high-diversity sites than at low-diversity sites. Our findings highlight the importance of local abiotic and biotic conditions in predicting grassland responses to anthropogenic nutrient and climate changes.EEA Santa Cruz, INTAFil: Bondaruk, V. F. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura (IFEVA); Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura (IFEVA); ArgentinaFil: Bondaruk, V. F. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Recursos Naturales y Ambiente. Cátedra de Ecología; Argentina.Fil: Bondaruk, V. F. University of Bayreuth. Bayreuth Center of Ecology and Environmental Research (BayCEER). Disturbance Ecology and Vegetation Dynamics; AlemaniaFil: Xu, C. Chinese Academy of Agricultural Sciences. Institute of Agricultural Resources and Regional Planning. State Key Laboratory of Efficient Utilization of Arable Land in China; China.Fil: Xu, C. Chinese Academy of Agricultural Sciences. Institute of Agricultural Resources and Regional Planning. Key Laboratory of Arable Land Quality Monitoring and Evaluation, Ministry of Agriculture and Rural Affairs; China.Fil: Wilfahrt, Peter A. University of Minnesota. Department of Ecology, Evolution, and Behavior; Estados UnidosFil: Yahdjian, Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura (IFEVA); Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura (IFEVA); ArgentinaFil: Yahdjian, Laura. Universidad de Buenos Aires. Facultad de Agronomía; Argentina.Fil: Yu, Q. Beijing Forestry University. School of Grassland Science; China.Fil: Yu, Q. Beijing Forestry University. State Key Laboratory of Efficient Production of Forest Resources; China.Fil: Borer, Elizabeth T. University of Minnesota. Department of Ecology, Evolution, and Behavior; Estados UnidosFil: Jentsch, Anke. University of Bayreuth. Disturbance Ecology, Bayreuth Center of Ecology and Environmental Research (BayCEER); AlemaniaFil: Seabloom, Eric William. University of Minnesota. Department of Ecology, Evolution, and Behavior; Estados UnidosFil: Smith, Melinda D. Colorado State University. Department of Biology; Estados Unidos.Fil: Smith, Melinda D. Colorado State University. Graduate Degree Program in Ecology; Estados Unidos.Fil: Alberti, Juan. Universidad Nacional de Mar del Plata. Instituto de Investigaciones Marinas y Costeras (IIMyC). Laboratorio de Ecología; Argentina.Fil: Alberti, Juan. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Peri, Pablo Luis. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina.Fil: Peri, Pablo Luis. Universidad Nacional de la Patagonia Austral; Argentina.Fil: Peri, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Hautier, Yann. Utrecht University. Department of Biology. Ecology and Biodiversity Group; Países Bajo