Estimation of evapotranspiration empirical coefficients of scots pine (Pinus sylvestris) under climate change conditions

Abstract

The aim of this study was to assess the feasibility of estimating the evapotranspiration of Scots pine (Pinus silvestris) using an indirect method. The field experiment was conducted at the Agro and Hydrometeorology Observatory of the Faculty of Environmental Engineering and Geodesy of the Wrocław University of Life Sciences in Poland from 1 May to 31 October from 2016 to 2019. The experiment covered the period from the 6th to the 9th year of cultivation of Scots pine (Pinus silvestris) on arable land. Evapotranspiration of Scots pine (ETR) was measured in soil evaporometers of 0.3 m2 and 0.7 m soil monolith thickness, with a daily time step, in triplicate. In order to avoid the oasis effect, the soil evaporometers were installed so that the measured trees grew in a compact enclave, as they do under natural conditions. In parallel, the actual evaporation values from the free water surface were measured directly with the EWP 992 evaporometer, and the daily indicator evaporation values were calculated using the FAO Penman-Monteith formula. In the next step, using evaporation measurements from the EWP 992 evaporometer and determined with the FAO Penman-Monteith formula, decadal and monthly empirical coefficients were determined to estimate the evapotranspiration of Scots pine. Evaluation of the weather conditions in the individual years of the experiment was also carried out, relating it to the normative multi-year period 1981–2010.