Merging community and ecosystem ecology via litter decomposition

We like to do science using interdisciplinary approaches because we think this is the best way to face the humanity’s greatest challenges. Combining community and ecosystem ecology aspects we can answer global ecological questions that matter for ecosystem management. The decomposition of leaf and root litter is heavily influenced by plant traits and soil (microbes and fauna) communities, and it is crucial to the regulation of soil C and N dynamics. We have been looking at the biotic and abiotic drivers of litter decomposition in aquatic and terrestrial environments, and across temporal stages of litter decay. This research has been done in collaboration with Diana Wall (Colorado State University) and Stephan Hättenschwiler (CNRS). We have also tested the linkages between plant community assembly, soil microbes and ecosystem functioning using plant trait distributions in microcosms experiments across six global biomes and 90 litter species, in collaboration with Nicolas Gross (INRA), Yoann Le Bagousse-Pinguet (CNRS) & Hugo Sáiz (U Bern).

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Nowadays, we face the major challenge of feeding ten billion people by 2050. At the same time, synthetic fertilizers and pesticides are being restricted because of their major environmental impacts. This situation requires that approaches proved useful during the Green Revolution transition towards more sustainable strategies capable of increasing crop production, its stability over time and its resistance to climate change. Agroecology advocates doing so by optimizing ecosystem processes key for crop yield (soil C storage, soil N retention, pollination) and promoting above and belowground biodiversity, while decreasing external inputs. We have been looking at the effects of organic farming and crop diversity on crop yield and ecosystem multifunctionality in European arable lands in the context of two European projects (Eco-Serve and Digging Deeper). We also mantain several agricultural trials at La Poveda Experimental Farm addressing the effects of sustainable practices (no till, cover crops  and AMF inoculation) and climate change on multiple agricultural goals.

Agroecology

Soil carbon in natural and agroecosystems

Soils represent the largest C pool in terrestrial ecosystems. The fate of the soil C pool is a pressing issue under ongoing climate change, as even subtle losses may represent a substantial contribution to the buildup of atmospheric CO2. Global warming is expected to accelerate soil C losses via the microbial decomposition of soil organic matter, representing a positive land C-climate feedback  that is embedded in the IPCC models.  In agricultural soils, SOM is key for crop production, but soil C stocks are drastically reduced after agricultural conversion, reinforcing climate change. Understanding, protecting and building soil C in natural and agroecosystems is one of the most promising natural climate solutions at hand, and we are working on related lines of research with César Plaza, Mark Bradford, Fernando Maestre, Jiansheng Ye and Manu Delgado-Baquerizo

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Crop domestication: ecosystem responses and plant microbiome

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Beyond driving the effects of farming practices, plant traits and soil microbes may be directly manipulated via plant breeding to impact key ecosystem services for crop yield. So far, plant

breeding programs have seek to enhance production by focusing on traits such as seed quantity or pest resistance. We argue that plant breeding should focus on traits with positive effects on soil C storage, biodiversity effects,  beneficial plant-microbial interactions & yield resistance to climate change.  In this line, the comparison of domesticated (modern crops) vs. old (wild progenitors) crop genotypes is a meaningful framework to guide ecosystem services-oriented plant breeding, and to address whether domestication has disrupted the ability of modern crops to interact with microbial communities across different plant compartments. In collaboration with Rubén Milla and Manuel Delgado-Baquerizo, we are looking at the microbiome, litter decomposition, soil functioning and diversity effects across > 20 domesticated-wild progenitors pairs from important staple crops such as cereals (C4 and C3), legumes, and forbs. We have also partnered with the Global Initiative of Crop Microbiome and Sustainable Agriculture ,  to compare the plant microbiomes of potato, rice, maize, wheat and cotton vs their wild progenitors at a global scale.

Systematic reviews and meta-analysis

Scientific literature syntheses have experienced a major change in the last 25 years, from purely descriptive summaries of (part of) the available literature, to systematic searching using online databases , data extraction from articles and complex analytical tools. We love meta-analyses. They allow us to explore consistent patterns across large spatial scales and environmental conditions. We actually believe that meta-analyses should constitute a first chapter in any PhD thesis. We particularly like to combine meta-analytical tools with structural equation modeling, to disentangle the relative importance of climatic, soil, plant and methodological variables as drivers of the effect size of a particular treatment. We have conducted meta-analyses addressing the effects of soil fauna on litter decomposition, the links between the responses of soil microbes and ecosystem functioning to global change, the effects of organic farming on soil C accumulation, the responses of primary productivity to precipitation extremes, or the responses of soil enzymes to experimental warming.

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