Evapotranspiration and Transpiration Dynamics on Pedunculate Oak Stands in Spačva Forest Using MODIS Evapotranspiration

The key variable in the water cycle, energy cycle, climate and carbon flow over land surfaces, and an important indicator of ecosystem functions and health is evapotranspiration (ET) It is defined as the total amount of water transported from land to the atmosphere and consists of evaporation from land and bodies of water (E) and plant transpiration (T). In 2019 and 2020, measurements of xylem sap flow were made in the Spačva forest (Croatia) of pedunculate oak on four plots, which can be linked to the T rate. T values measured in field were compared to satellite-based MODIS product MOD16A2GF with modelled ET. The maximum ET values measured by remote sensing were about 40 L m-2 per 8 days. In the vegetation period up to the season transpiration maximum, MODIS ET successfully predicted T on all surfaces. Modelled T for all Spačva area was shown on maps where seasonal change and local differences can be observed. The results showed opportunities to use this product in monitoring of forest condition.