Litter breakdown in streams of the Agüera catchment: influence of dissolved nutrients and land use

Abstract

1. The breakdown of oak (Quercus robur L.), chestnut (Castanea sativa Miller) and eucalypt (Eucalyptus globulus Labill.) litter enclosed in 5‐mm mesh bags was compared between first‐order headwaters (two with native riparian forest and two with eucalypt plantations) and a third‐order reach of Agüera stream. Weight loss and dynamics of phosphorus and nitrogen in litter were studied for a period of 155 days. 2. Among the different sites, processing rates ranged from 0.0045 to 0.0080 day–1 for chestnut leaf litter, from 0.0036 to 0.0051 day–1 for oak, and from 0.0027 to 0.0158 day–1 for eucalypt. 3. The availability of nutrients in water clearly influenced nitrogen and phosphorus dynamics in litter. In headwater reaches, net immobilization was not observed and losses of phosphorus and nitrogen followed mass loss. However, there was an enrichment of litter at the low reach, where influence of human settlements—located upstream—could lead to a greater availability of phosphorus in water. 4. The enhancement of litter decay by the exogenous nutrient supply depended on leaf quality, as only the processing rate of eucalypt increased at the nutrient‐rich site. 5. The processing rates differed little among headwaters, suggesting that riparian forest type, i.e. deciduous forest v eucalypt plantations, did not affect litter decay in the stream.

Influences of leaf toughness and nitrogen content on in‐stream processing and nutrient uptake by litter in a Waikato, New Zealand, pasture stream and streamside channels

“…Our channel rate for Pinus radiata was only c. 18% of rates measured in a headwater stream in the Blue Ranges, Victoria, Australia (O'Keefe & Lake 1987) (0.0185 and 0.0224 day" 1 ), but was within the range of previous measurements for other conifer species in North American and European streams Anderson & Sedell 1979;Rosset et al 1982;Graca & Pereira 1995). The processing rate we obtained for Eucalyptus regnans was 1.3-to 2.4-fold higher than in a Victorian mountain stream (Blackburn & Petr 1979), but within the range reported for E. globulus in Spanish streams (Molinero et al 1996) and E. viminalis in streams of south-east Australian (Campbell et al 1992). Our stream and channel mass loss rates for Populus x canadensis were, respectively, twice and half that reported for Populus fremontii in a Sonoran Desert stream (Schade & Fisher 1997), whereas the channel rates were similar to those for P .…”

Macroinvertebrate communities along a third-order Iberian stream

“…This suggested difference in shredder efficiency could be linked to spatial changes in detritus quality because 3 study sites with differing composition of CPOM were compared . Furthermore, the nutrient content of leaf litter, one of the main components of its quality (Anderson & Sedell 1979, Cummins & Klug 1979, Webster & Benfield 1986, Boulton & Boon 1991, increases with conditioning time at downstream reaches of the Agüera stream, but not at oligotrophic headwaters (Pozo 1993, Molinero et al 1996. Nevertheless, these spatial changes in detritus quality, if they existed, could not explain the observed spatial pattern of shredder abundance.…”

Assessing impact of eucalyptus plantations on benthic macroinvertebrate communities by a litter exclusion experiment

“…On the other hand, oak litter enters our stream naturally, but as in the case of eucalyptus, its processing is slow (Molinero et al 1996) due to the thick cuticle and the high content of phenolic compounds (Covelo & Gallardo 2001). Nevertheless, it seems that detritivores consume and efficiently transform oak litter to animal biomass (González & Graça 2003), but do not conclude its development and die when eat eucalyptus (see , 1999.…”