ECOVAP: Effect of climate and management on evapotranspiration in agricultural ecosystems

Context

Water is an essential resource for terrestrial ecosystems and crucial for plant growth. Climate change increases the frequency of heatwaves and droughts affecting the ecosystem water cycle. Evapotranspiration (ET), i.e., the water evaporated from surfaces (E) and transpired by the vegetation (T), will be affected by those future conditions with potential implications for agriculture (e.g., productivity loss, change in species and harvest frequencies, irrigation needs). The biotic and abiotic part of ET must be known to correctly represent the contribution of vegetation to ET in models, relevant also for upscaling ET from plant to ecosystem level. However, even though ET partitioning methods exist, direct measurements of E and T for validation are still lacking as well as knowledge on the effect of agricultural management and drought on ET under current and future climate.

Objectives

The aim of this project is to evaluate and partition ET in Swiss agroecosystems along a management and climate gradient and to assess the influence of extreme events, such as droughts, on the ecosystem water vapor exchange. We will focus on four sites which cover the major agricultural land use in Switzerland (one cropland and three grasslands at different elevations). More specifically, the objectives are:

  1. to determine drivers of ET on different spatiotemporal scales
  2. to partition ET into evaporation and transpiration
  3. to assess the influence of soil and atmospheric dryness on ET and water use efficiency (i.e., the ratio of the amount of carbon dioxide fixed by photosynthesis and ET)
  4. to predict how ET will develop in a future climate.

We will use data and measurements from the plot to the ecosystem scale and conduct data analyses using statistical and machine learning models. This project will improve our knowledge on the mechanisms of ET in agroecosystems with an interdisciplinary approach (micrometeorology, ecophysiology and agricultural sciences), relevant for sustainable agriculture in a changing climate.

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