Owing to their high water retention, the volcanic ash-soils of the Northern Andean highlands (páramos) can be considered as natural ‘water storage tanks’ for drinking water and for irrigation. Vegetation plays an important role in transferring rain to the soil and in controlling the soil water content. To assess this role, we quantified the stemflow process under rainfall simulations for seven of the main plants along an altitude gradient on the Pichincha volcano in Ecuador. The volume of water transferred into the soil was higher at the lower rainfall intensity than at the higher intensity. The results were compared to the stemflow measured with potato and maize crops growing in the lower altitude range. The results showed that the relative volume of stemflow increased with altitude from 8% in the crop area to 58% in the upper part of the catena. Low values of stemflow were associated with potatoes and maize annual short-cycle crops while high values were associated with the natural vegetation. For cultivated crops rainwater interception by stemflow delayed the soil surface crusting and runoff process. This study shows that rainwater interception by vegetation is of great importance for soil water recharge in these Andisols.

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