Spatial and temporal dynamics of atmospheric water and nutrient inputs in tropical mountain forests of southern Ecuador

Resumen

As part of an interdisciplinary research program, the spatial and temporal variability of precipitation and associated nutrient inputs in southern Ecuador have been investigated since January 2002. The study site is located at the northern margin of the Podocarpus National Park in the vicinity of Loja, about 500 km south of Quito, at altitudes ranging from 1800 to 3180 m.a.s.l. Due to its low density, the conventional rainfall station network fails to register the highly variable distribution of rain whereas fog is not accounted for at all. Hence, a new measurement infrastructure had to be installed. For the first time in a tropical montane forest setting, a Weather Radar was used, covering a radius of 60 km and reaching from the Amazon Basin to the coastal plains of the region. Furthermore, a dense network of sampling stations provided data about the altitudinal gradient of fog water inputs and the chemical properties of the different precipitation types. This combined approach provided important information on the formative processes of rain events on the eastern escarpment of the Andes. Rainfall distribution proved far more variable than previously known and strongly coupled to the orographic characteristics of the landscape. Maxima occurred especially on the exposed mountain slopes in the eastern parts of the Radar range, whereas the highest crests of the Andes received less precipitation. The study area has two cloud condensation levels, occurring at 1500–2000 m and 2500–3500 m.a.s.l., respectively. […]