Estimation of canopy ecohydrological parameters of oriental beech and chestnut-leaved oak stands in Hyrcanian vegetation region

Calculating the amount of canopy ecohydrological parameters is the main step in rainfall partitioning modeling, and by calculating the amount of ecohydrological parameters, it is possible to predict the amount of throughfall, stemflow, and rainfall interception per rain storm. Therefore, this study aimed to evaluate the canopy echohydrological parameters of three oriental beech (Fagus orientalis Lipsky) stands and three chestnut-leaved oak (Quercus castaneifolia C. A. Mey.) located in the Hyrcanian vegetation region in the annual-based time scale. The ecohydrological parameters studied included canopy saturation point, canopy water storage capacity, free throughfall coefficient, and the ratio of mean evaporation rate from canopy to the mean rainfall intensity. On average, the canopy saturation point was 5.37 mm in the chestnut-leaved oak and 6.29 mm in the oriental beech. Also, on average, the canopy water storage capacity of the oriental beech (2.08 mm) was higher than that of the chestnut-leaved oak (1.15 mm). The mean rainfall magnitudes in the chestnut-leaved oak and oriental beech stands were 20.0 and 16.2 mm, respectively. The average relative interception in the oriental beech (36.9%) was slightly higher than the chestnut-leaved oak (33.5%). The average free throughfall coefficient and the ratio of mean evaporation rate from canopy to the mean rainfall intensity were calculated to be 0.50 and 0.25 for the oriental beech and 0.71 and 0.36 for the chestnut-leaved oak. By knowing the values of canopy ecohydrological parameters, thinning and pruning silvicultural treatments can be applied in stands with high water storage capacity and low free throughfall coefficient to reduce rainfall interception.