Assessments of ecosystem functioning

Understanding ecosystem functions:

• • Evapotranspiration, the sum of water evaporation from the soil and transpiration from living organisms
  • Net ecosystem exchange, the net amount of atmospheric CO₂ captured by the ecosystem
  • GHG emissions, the net amount of CO₂ , CH₄ and N₂O emitted by the ecosystem
  • Indeed, in some ecosystems not only human activity but also living organisms can release some of these gases in the atmosphere

We measure climate and soil parameters at least every half-hour:

• • Air temperature
  • Air relative humidity
  • Precipitation
  • Greenhouse gas concentrations (CO₂, CH₄ , N₂O)
  • Energy influx in the mesocosm (photosynthetic photon flux density: PPFD)
  • Part of this energy that can be used by the plants for photosynthesis (Photosynthetically Active Radiation: PAR)
  • Soil temperature at 5 depths (10, 20, 35, 60, 140cm) in triplicates
  • Soil water content at 5 depths (10, 20, 35, 60, 140cm) in triplicates
  • Soil water tension (force necessary for plant roots to extract water from the soil) at 5 depths, in triplicates
  • Soil electrical conductivity (amount of salts in soil) at 5 depths, in triplicates
  • Mesocosm weight
  • Amount of water leaching from the mesocosm

We take samples in the mesocosm at regular intervals to monitor:

• • Soil biochemistry (chemical composition of the soil and the soil water: DOC, DON, NO3-, NH4+, PO4+, Al, Ca, Fe, K, Mg. Na, Cl, Br, S)
  • Isotopic composition of Carbon in soil, atmosphere, plants and soil microorganisms
  • Soil microbial communities (fungi, bacteria)
  • Soil micro and mesofauna communities (mites, springtails and all soil animals < 1cm)
  • Plant cover (monitored using automated camera pictures, phenocams)