Annual fog deposition and atmospheric chemical deposition were evaluated for a strongly fog-affected coniferous forest at Chi-Lan, Taiwan. Fog capture efficiencies of Chamaecyparis obtusa var. formosana leaves were measured at three heights within the canopy using in situ exposure experiments under contrasting climatic conditions. The efficiencies obtained in this way were multiplied times leaf biomass to calculate stand-level fog deposition rates. Furthermore, a statistical model was developed, linking fog deposition rate to visibility. Using the latter model, annual fog deposition from March 2003 to February 2004 was calculated to be 297 mm, or ~9% of the total atmospheric water input. Fog contributions exhibited a highly seasonal pattern that depended mainly on the amount of precipitation. Due to the higher chemical concentrations of fog compared to precipitation, nutrient deposition via fog played a significant role. Inorganic nitrogen was absorbed by the canopy whereas potassium was leached. It is concluded that fog constitutes an important factor influencing the water and nutrient dynamics of the montane forest ecosystem under study.
The concept of a “montane cloud forest belt” has been recognized in Taiwan for decades (Su, 1984). Although there were few meteorological records on cloud heights at the time, the elevational range of the cloud belt was inferred from temperature lapse rates as calculated from data of more than 150 weather stations (Su, 1984).