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Land Carbon - Climate Feedback

 

The top two meters of soils store more than 2,200–2,500 Pg of organic C, representing three times the amount stored in the atmosphere as CO2. The size of this C reservoir is annually balanced because large C losses to the atmosphere through soil respiration are offset by C gains to the soil from plant photosynthesis. Anthropogenic climate warming is perturbing this balance, accelerating soil C losses via the microbial decomposition of soil organic matter. This land C–climate feedback has received considerable research attention in the past decades and it is embedded in the IPCC models, but there appears to be no consensus on its magnitude. Consequently, the potential for soil C losses under warming are not factored into climate policy negotiations.

We are investigating climate warming effects on the soil carbon of natural, agricultural and urban ecosystems. Our research focuses on global soil C distribution, mineral-associated organic carbon, incorporation of microbial physiology and community ecology into soil C models. Overall, we aim to protect and build soil C as a natural climate solution.

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Biodiversity and Ecosystem Functioning

The current biodiversity crisis is, jointly with climate change, one of the main global change drivers affecting Earth’s ecosystems. We cannot address biodiversity loss without tackling climate change. Biodiversity is of pivotal importance for maintaining ecosystem functions, such as primary production, litter decomposition, and soil nutrient cycling. Despite the important advances in our understanding of the role of plant diversity in natural and managed ecosystems, we still ignore multiple aspects that are key to track the consequences of biodiversity loss on ecosystems, undertake effective restoration actions, and engineer biodiversity effects in agricultural and urban systems. We combine community and ecosystem ecology approaches to answer questions that matter for management.

We use litter decomposition as a model system, as it represents the interface between plant communities and soil processes. We are particularly interested in the relative importance of biotic and abiotic drivers of litter decomposition across aquatic - terrestrial comparisons, temporal stages of litter decay, and terrestrial biomes. We also investigate the insurance hypothesis (positive biodiversity effects on ecosystem stability). We link global field surveys of plant and soil biodiversity with NDVI temporal series, and address the stability of crop production and urban lawns in response to climate warming and management in long-term trials.

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Crop Domestication: Ecosystem Responses and Plant Microbiome

Ancient domestication and major advances in plant breeding programs have altered crop phenotypes for increased yield and promoted a number of traits regarded as favorable by humans. However, these directed phenotypic changes in leaf and root traits have also promoted a number of unintentional effects that condition sustainable agricultural production. For instance, these effects may go from altering the decomposition of plant residues and soil nutrient cycling in agricultural fields, to disrupting the ability of crops to benefit from biodiversity effects when growing in mixtures, or to limiting the interaction of crops with beneficial microbial communities.

 

We compare domesticated crop genotypes (modern crops) vs. wild progenitors across major crops for global agriculture (C3 and C4 cereals, legumes, oilseeds, vegetables). We are coordinating MICROWILD, a global consortium investigating the plant microbiome of crop wild progenitors in their native areas of distribution. This cool project aims to harness key microbial-host interactions for sustainable and climate change-resilient crop production.

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Systematic reviews and meta-analysis

Scientific literature syntheses have experienced a major change in the last 30 years, from descriptive summaries of the literature, to systematic searching, data extraction from articles and complex analytical tools such as acyclic graphs, machine learning and meta-regression. We use meta-analyses to explore consistent patterns across large spatial scales and environmental conditions that allow us to infer global change effects on biogeochemistry and biodiversity by means of space-for-time substitutions. For instance, we have published several global meta-analyses over the years: soil fauna effects on litter decomposition (García-Palacios et al. 2013 Ecol Lett), soil microbes and ecosystem functions responses to global change (García-Palacios et al. 2015 Glob Change Biol), primary productivity responses to precipitation extremes (Wilcox et al. 2017 Glob Change Biol), plant traits driving organic farming effects on soil C sequestration (García-Palacios et al. 2017 J Appl Ecol), soil enzymes responses to climate warming (Chen et al. 2018 Glob Change Biol), soil ammonia oxidizers and denitrifiers responses to N deposition (Zhang et al. 2022 Glob Change Biol).

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