Ecosystem coupling:A unifying framework to understand the functioning and recovery of ecosystems

Global change frequently disrupts the connections among species, as well as among species and their environment, before the most obvious impacts can be detected. Therefore, we need to develop a unified conceptual framework that allows us to predict early ecological impacts under changing environments. The concept of coupling, defined as the multiple ways in which the biotic and abiotic components of ecosystems are orderly connected across space and/or time, may provide such a framework. Here, we operationally define the coupling of ecosystems based on a combination of correlational matrices and a null modeling approach. Compared with null models, ecosystems can be (1) coupled; (2) decoupled; and (3) anticoupled. Given that more tightly coupled ecosystems displaying higher levels of internal order may be characterized by a more efficient capture, transfer, and storage of energy and matter (i.e., of functioning), understanding the links between coupling and functioning may help us to accelerate the transition to planetary-scale sustainability. This may be achieved by promoting self-organized order

Application of biostimulant products and biological control agents in sustainable viticulture: A review

Current and continuing climate change in the Anthropocene epoch requires sustainable agricultural practices. Additionally, due to changing consumer preferences, organic approaches to cultivation are gaining popularity. The global market for organic grapes, grape products, and wine is growing. Biostimulant and biocontrol products are often applied in organic vineyards and can reduce the synthetic fertilizer, pesticide, and fungicide requirements of a vineyard. Plant growth promotion following application is also observed under a variety of challenging conditions associated with global warming. This paper reviews different groups of biostimulants and their effects on viticulture, including microorganisms, protein hydrolysates, humic acids, pyrogenic materials, and seaweed extracts. Of special interest are biostimulants with utility in protecting plants against the effects of climate change, including drought and heat stress. While many beneficial effects have been reported following the application of these materials, most studies lack a mechanistic explanation, and important parameters are often undefined (e.g., soil characteristics and nutrient availability). We recommend an increased study of the underlying mechanisms of these products to enable the selection of proper biostimulants, application methods, and dosage in viticulture. A detailed understanding of processes dictating beneficial effects in vineyards following application may allow for biostimulants with increased efficacy, uptake, and sustainability.KJ wishes to acknowledge financial support (3710473400); MS-M thanks to RTI2018-099417-B-I00 (Spanish Ministry of Science, Innovation and Universities cofunded with EU FEDER funds); JB wish to acknowledge the Conselho Nacional de Desenvolvimento Científico e Tecnológico/Brasil (CNPQ process number 309477/2021-2); RO-H is supported by the Ramón y Cajal program from the MICINN (RYC-2017 22032), PAIDI 2020 (Ref. 20_00323), AEI GGOO 2020 (GOPC-CA-20-0001), “José Castillejo” program from the “Ministerio de Universidades” (CAS21/00125) and PID2019-106004RA-I00/AEI/10.13039/501100011033. SM and GT thanks to Ministerio de Ciencia e Innovación (grant PID2020-114330GB-100). PAIDI2020 from Junta de Andalucía, grant P18-RT-1401 to SM, MD, and GT is also acknowledged. GT acknowledge the support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI)

Drivers of the microbial metabolic quotient across global grasslands

Aim: The microbial metabolic quotient (MMQ; mg CO2-C/ mg MBC/h), defined as the amount of microbial CO2 respired (MR; mg CO2-C/ kg soil/h) per unit of microbial biomass C (MBC; mg C/kg soil), is a key parameter for understanding the microbial regulation of the carbon (C) cycle, including soil C sequestration. Here, we experimentally tested hypotheses about the individual and interactive effects of multiple nutrient addition (nitrogen + phosphorus + potassium + micronutrients) and herbivore exclusion on MR, MBC and MMQ across 23 sites (five continents). Our sites encompassed a wide range of edaphoclimatic conditions; thus, we assessed which edaphoclimatic variables affected MMQ the most and how they interacted with our treatments. Location: Australia, Asia, Europe, North/South America. Time period: 2015–2016. Major taxa: Soil microbes. Methods: Soils were collected from plots with established experimental treatments. MR was assessed in a 5-week laboratory incubation without glucose addition, MBC via substrate-induced respiration. MMQ was calculated as MR/MBC and corrected for soil temperatures (MMQsoil). Using linear mixed effects models (LMMs) and structural equation models (SEMs), we analysed how edaphoclimatic characteristics and treatments interactively affected MMQsoil. Results: MMQsoil was higher in locations with higher mean annual temperature, lower water holding capacity and lower soil organic C concentration, but did not respond to our treatments across sites as neither MR nor MBC changed. We attributed this relative homeostasis to our treatments to the modulating influence of edaphoclimatic variables. For example, herbivore exclusion, regardless of fertilization, led to greater MMQsoil only at sites with lower soil organic C (< 1.7%). Main conclusions: Our results pinpoint the main variables related to MMQsoil across grasslands and emphasize the importance of the local edaphoclimatic conditions in controlling the response of the C cycle to anthropogenic stressors. By testing hypotheses about MMQsoil across global edaphoclimatic gradients, this work also helps to align the conflicting results of prior studies.info:eu-repo/semantics/publishedVersio

Soil fungal abundance and plant functional traits drive fertile island formation in global drylands

Dryland vegetation is characterized by discrete plant patches that accumulate and capture soil resources under their canopies. These “fertile islands” are major drivers of dryland ecosystem structure and functioning, yet we lack an integrated understanding of the factors controlling their magnitude and variability at the global scale.EEA BarilocheFil: Ochoa-Hueso, Raúl. Universidad Autónoma de Madrid. Department of Ecology; EspañaFil: Eldridge, David J. University of New South Wales. School of Biological, Earth and Environmental Sciences; AustraliaFil: Delgado-Baquerizo, Manuel. University of Colorado. Cooperative Institute for Research in Environmental Sciences; Estados Unidos. Universidad Rey Juan Carlos. Escuela Superior de Ciencias Experimentales y Tecnología. Departamento de Biología y Geología, Física y Química Inorgánica; EspañaFil: Soliveres, Santiago. University of Bern. Institute of Plant Sciences; SuizaFil: Bowker, Matthew A. Northern Arizona University. School of Forestry; Estados UnidosFil: Gross, Nicolás. Universidad Rey Juan Carlos. Escuela Superior de Ciencias Experimentales y Tecnología. Departamento de Biología y Geología, Física y Química Inorgánica; España. Institut Nationale de la Recherche Agronomique; Francia. Université La Rochelle. Centre d’étude biologique de Chizé; FranciaFil: Le Bagousse-Pinguet, Yoann. Universidad Rey Juan Carlos. Escuela Superior de Ciencias Experimentales y Tecnología. Departamento de Biología y Geología, Física y Química Inorgánica; EspañaFil: Quero, José L. Universidad de Córdoba. Escuela Técnica Superior de Ingeniería Agronómica y de Montes. Departamento de Ingeniería Forestal: EspañaFil: García-Gómez, Miguel. Universidad Rey Juan Carlos. Escuela Superior de Ciencias Experimentales y Tecnología. Departamento de Biología y Geología, Física y Química Inorgánica; EspañaFil: Valencia, Enrique. Universidad Rey Juan Carlos. Escuela Superior de Ciencias Experimentales y Tecnología. Departamento de Biología y Geología, Física y Química Inorgánica; EspañaFil: Arredondo, Tulio. Instituto Potosino de Investigación Científica y Tecnológica. División de Ciencias Ambientales; MéxicoFil: Beinticinco, Laura. Universidad Nacional de La Pampa. Facultad de Agronomía; ArgentinaFil: Bran, Donaldo Eduardo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche; ArgentinaFil: Cea, Alex. Universidad de La Serena. Departamento de Biología; ChileFil: Coaguila, Daniel. Instituto de Ensino Superior de Rio Verde; BrasilFil: Dougill, Andrew J. University of Leeds. School of Earth and Environment; Gran BretañaFil: Espinosa, Carlos I. Universidad Técnica Particular de Loja. Departamento de Ciencias Naturales; EcuadorFil: Gaitan, Juan Jose. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Suelos; ArgentinaFil: Guuroh, Reginald T. University of Cologne. Botanical Institute. Range Ecology and Range Management Group; Alemania. CSIR-Forestry Research Institute of Ghana; GhanaFil: Guzmán, Elizabeth. Universidad Técnica Particular de Loja. Departamento de Ciencias Naturales; EcuadorFil: Gutiérrez, Julio R.. Universidad de La Serena. Departamento de Biología; Chile. Centro de Estudios Avanzados en Zonas Áridas (CEAZA); Chile. Instituto de Ecología y Biodiversidad; ChileFil: Hernández, Rosa M. Universidad Experimental Simón Rodríguez. Centro de Agroecología Tropical. Laboratorio de Biogeoquímica; VenezuelaFil: Huber-Sannwald, Elisabeth. Instituto Potosino de Investigación Científica y Tecnológica. División de Ciencias Ambientales; MéxicoFil: Jeffries, Thomas. Western Sydney University. Hawkesbury Institute for the Environment; AustraliaFil: Linstädter, Anja. University of Cologne. Botanical Institute. Range Ecology and Range Management Group; AlemaniaFil: Mau, Rebecca L. Northern Arizona University. Center for Ecosystem Science and Society: Estados UnidosFil: Monerris, Jorge. Université du Québec à Montréal. Pavillon des Sciences Biologiques. Département des Sciences Biologiques; CanadáFil: Prina, Anibal. Universidad Nacional de La Pampa. Facultad de Agronomía; ArgentinaFil: Pucheta, Eduardo. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Biología; ArgentinaFil: Stavi, Ilan. Dead Sea and Arava Science Center, IsraelFil: Thomas, Andrew. Aberystwyth University. Department of Geography and Earth Sciences; Gran BretañaFil: Zaady, Eli. Agricultural Research Organization. Gilat Research Center. Natural Resources; IsraelFil: Singh, Brajesh K. Western Sydney University. Hawkesbury Institute for the Environment; Australia. Western Sydney University. Global Centre for Land-Based Innovation; AustraliaFil: Maestre, Fernando T. Universidad Rey Juan Carlos. Escuela Superior de Ciencias Experimentales y Tecnología. Departamento de Biología y Geología, Física y Química Inorgánica; Españ

Soil fungal abundance and plant functional traits drive fertile island formation in global drylands

International audience1.Dryland vegetation is characterised by discrete plant patches that accumulate and capture soil resources under their canopies. These “fertile islands” are major drivers of dryland ecosystem structure and functioning, yet we lack an integrated understanding of the factors controlling their magnitude and variability at the global scale.2.We conducted a standardized field survey across two hundred and thirty-six drylands from five continents. At each site, we measured the composition, diversity and cover of perennial plants. Fertile island effects were estimated at each site by comparing composite soil samples obtained under the canopy of the dominant plants and in open areas devoid of perennial vegetation. For each sample, we measured fifteen soil variables (functions) associated with carbon, nitrogen and phosphorus cycling and used the Relative Interaction Index to quantify the magnitude of the fertile island effect for each function. In eighty sites, we also measured fungal and bacterial abundance (quantitative PCR) and diversity (Illumina MiSeq).3.The most fertile islands, i.e. those where a higher number of functions were simultaneously enhanced, were found at lower-elevation sites with greater soil pH values and sand content under semiarid climates, particularly at locations where the presence of tall woody species with a low specific leaf area increased fungal abundance beneath plant canopies, the main direct biotic controller of the fertile island effect in the drylands studied. Positive effects of fungal abundance were particularly associated with greater nutrient contents and microbial activity (soil extracellular enzymes) under plant canopies.4.Synthesis. Our results show that the formation of fertile islands in global drylands largely depends on: (i) local climatic, topographic and edaphic characteristics, (ii) the structure and traits of local plant communities and (iii) soil microbial communities. Our study also has broad implications for the management and restoration of dryland ecosystems worldwide, where woody plants are commonly used as nurse plants to enhance the establishment and survival of beneficiary species. Finally, our results suggest that forecasted increases in aridity may enhance the formation of fertile islands in drylands worldwide

The fate of carbon in a mature forest under carbon dioxide enrichment

Atmospheric carbon dioxide enrichment (eCO2) can enhance plant carbon uptake and growth1 5, thereby providing an important negative feedback to climate change by slowing the rate of increase of the atmospheric CO2 concentration6. Although evidence gathered from young aggrading forests has generally indicated a strong CO2 fertilization effect on biomass growth3 5, it is unclear whether mature forests respond to eCO2 in a similar way. In mature trees and forest stands7 10, photosynthetic uptake has been found to increase under eCO2 without any apparent accompanying growth response, leaving the fate of additional carbon fixed under eCO2 unclear4,5,7 11. Here using data from the first ecosystem-scale Free-Air CO2 Enrichment (FACE) experiment in a mature forest, we constructed a comprehensive ecosystem carbon budget to track the fate of carbon as the forest responded to four years of eCO2 exposure. We show that, although the eCO2 treatment of +150 parts per million (+38 per cent) above ambient levels induced a 12 per cent (+247 grams of carbon per square metre per year) increase in carbon uptake through gross primary production, this additional carbon uptake did not lead to increased carbon sequestration at the ecosystem level. Instead, the majority of the extra carbon was emitted back into the atmosphere via several respiratory fluxes, with increased soil respiration alone accounting for half of the total uptake surplus. Our results call into question the predominant thinking that the capacity of forests to act as carbon sinks will be generally enhanced under eCO2, and challenge the efficacy of climate mitigation strategies that rely on ubiquitous CO2 fertilization as a driver of increased carbon sinks in global forests. © 2020, The Author(s), under exclusive licence to Springer Nature Limited

Effects of nutrient addition and soil drainage on germination of N-fixing and non-N-fixing tropical dry forest tree species

To develop generalised predictions regarding the effects of atmospheric nitrogen (N) and phosphorus (P) deposition on vegetation communities, it is necessary to account for the impacts of increased nutrient availability on the early life history stages of plants. Additionally, it is important to determine if these responses (a) differ between plant functional groups and (b) are modulated by soil drainage, which may affect the persistence of added nutrients. We experimentally assessed seed germination responses (germination proportion and germination energy, i.e. time to germination) of commonly occurring N-fixing and non-N-fixing tropical dry forest tree species found in India to simulated N and P deposition in well-drained soils, as well as soils with impeded drainage. When soils were not allowed to drain, germination proportion declined with nutrient addition, while germination energy remained unchanged. Stronger declines in germination proportion were observed for N-fixing species. In free-draining soils, nutrient addition did not affect germination proportion in either functional group. However, we detected a trend of delayed germination with nutrient addition, especially in N-fixers. Our results suggest that nutrient deposition can lead to potential shifts in functional dominance and tree community composition of tropical dry forests in the long term through its effects on early life stages of trees, although the mechanisms underlying the observed germination responses remain unclear. Further, such effects are likely to be spatially variable across the geographic range in which tropical dry forests occur depending on soil drainage properties

Soil net nitrogen mineralisation across global grasslands

Soil nitrogen mineralisation (N-min), the conversion of organic into inorganic N, is important for productivity and nutrient cycling. The balance between mineralisation and immobilisation (net N-min) varies with soil properties and climate. However, because most global-scale assessments of net N-min are laboratory-based, its regulation under field-conditions and implications for real-world soil functioning remain uncertain. Here, we explore the drivers of realised (field) and potential (laboratory) soil net N-min across 30 grasslands worldwide. We find that realised N-min is largely explained by temperature of the wettest quarter, microbial biomass, clay content and bulk density. Potential N-min only weakly correlates with realised N-min, but contributes to explain realised net N-min when combined with soil and climatic variables. We provide novel insights of global realised soil net N-min and show that potential soil net N-min data available in the literature could be parameterised with soil and climate data to better predict realised N-min