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POSITIVE EFFECTS OF LEGUMES ON SOIL ORGANIC CARBON STORAGE DISAPPEAR AT HIGH LEGUME PROPORTION ACROSS A WIDE RANGE OF ENVIRONMENTAL CONDITIONS IN GRASSLANDS IN THE PYRENEES
  • Antonio Rodríguez,
  • Rosa Canals,
  • Maria-Teresa Sebastià
Antonio Rodríguez
University of Lleida
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Rosa Canals
UPNA
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Maria-Teresa Sebastià
University of Lleida
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Abstract

Soil is the largest terrestrial carbon pool, making it crucial for climate change mitigation. To disentangle the relationships of plant guild diversity with soil organic carbon (SOC) storage at broad spatial scales, we applied diversity-interaction models to a regional grassland database. The questions were if: 1) positive effects of plant guild diversity on SOC at broad spatial scales are similar to experiments; 2) the enhancement of SOC by legumes is constant in natural grasslands; and 3) the effects of legumes on SOC depend on interactions with other guilds. SOC increased with legume proportion up to 15-20%, then decreased, across broad spatial scales. Additionally, legume effects were enhanced when grasses were dominant, which could be related to the strong capacity of grasses for capturing nitrogen; grass carbon exudates; the balance symbiotic/non-symbiotic nitrogen. Our findings can facilitate the elaboration of regional and local strategies to ameliorate the soil capacity to absorb carbon.