Rainfall interception in two tropical montane rain forests, Colombia

Abstract

AbstractRainfall interception was studied during one complete year in two montane rain forests in the Colombian Andes at altitudes of 2550 and 3370 m. Additional measurements were made in a subsequent period at 3370 m, comparing two plots with different tree genera. Special attention was paid to the possible consequences of the abundant epiphytic vegetation, representing a high but spatially variable storage capacity. On an annual basis, interception amounted to 262 mm (12.4 per cent) of 2115 mm incident precipitation at 2550 m, and to 265 mm (18.3 per cent) of 1453 mm incident precipitation at 3370 m. There was no evidence for fog precipitation. The fact that, in spite of lower annual rainfall and lower evaporation rate, absolute quantity of interception at 3370 m was not lower than at 2550 m is probably related to differences in rainfall distribution and canopy storage capacities. The different responses of the two tree genera (characterized by distinct epiphyte cover) and the lower interception after prolonged wet periods support the idea that epiphytes play a significant role in the interception process. A realistic description of the water balance of such ecosystems will require the adaptation of existing interception models.