Quantification of cloud water interception in the canopy vegetation from fog gauge measurements

With changes in climate looming, quantifying often-overlooked components of the canopy water budget, such as cloud water interception (CWI), is increasingly important. Commonly, CWI quantification requires detailed continuous measurements, which is extremely challenging, especially when throughfall is included. In this study, we propose a simplified approach to estimate CWI using the Rutter-type interceptionmodel,whereCWIinputs in the canopy vegetation are proportional to fog interception measured by an artificial fog gauge. The model requires the continuous acquisition of meteorological variables as input and calibration datasets. Throughfall measurements below the forest are used only for calibration and validation of the model; thus, CWI estimates can be provided even after the cessation of throughfall monitoring. This approach provides an indirect and undemanding way to quantify CWI by vegetation and allows the identification of its controlling factors, which could be useful to the comparison of CWI in contrasting land covers. The method is applied on a 2-year dataset collected in an endemic highland forest of San Cristobal Island (Galapagos). Our results show that CWI reaches 21%± 6%of the total water input during the first year, and 9%±2%during the second one. These values represent 32%±10% and 17% ± 5% of water inputs during the cool foggy season of the first and second year, respectively. The difference between seasons is attributed to a lower fog liquidwater during the second season.