Balances de hojarasca en dos arroyos forestados: Impacto de las plantaciones de eucalipto en el funcionamiento ecológico de un sistema lótico

Abstract

Leaf litter is the main energy source in small streams that drain forested watersheds. In this work, the impact of the eucalyptus plantation on the leaf litter budget in a headwater stream was studied. Two sampling sites were selected: site C, located in Salderrey stream which flows through deciduous forest, and site E, located in Jerguerón stream, which drains an eucalyptus plantation. Processing rates of the different species were estimated by incubations of leaf litter in 5 mm bags carried out from 1990 to 1996. Litter traps located on the stream banks measured leaf litter inputs from the riparian vegetation. Leaf litter transport was measured with drift nets located in the upper part of the study reaches. Benthic storage of leaf litter was estimated by collecting benthic samples with a Surber net. Leaf litter inputs were lower in the stream that flows through the eucalyptus plantation. Vegetation change also influenced the input way of the organic matter and its composition. Despite a reduction in the leaf litter inputs, more leaves were retained in the benthos at site E. Due to the higher retention in the eucalyptus plantation stream, leaf litter was processed more efficiently at this site. These observations suggest the importance of maintaining the natural riparian vegetation to protect the ecological functioning of small streams that flow through eucalyptus plantations. © Asociación Española de Limnología.