Processing of willow leaves in two Alberta Rocky Mountain streams

Abstract

Nylon bags of 3.5 mm and 0.25 mm mesh were used lo investigate the processing of Salix drummondiana Barratt leaves in two second order Alberta Rocky Mountain Creeks, Twin Creek and Cabin Creek. Micro‐organism processing and macroinvertebrate shredding of the leaves were significantly greater in Twin Creek where it was estimated that macroinvertebrate shredding was responsible for 45% of the weight loss. The decay coefficient (k = 0.0209) for the leaves in Twin Creek, the more typical Rocky Mountain stream, was similar to that reported for the fastest decaying leaves in warmer streams. The predominant shredder among the leaves in the mesh bags, Zapada columbiana (Classen) (Plecoptera, Nemouridae) was also the most abundant macroinvertebrate in the benthos of Twin Creek. In Cabin Creek the predominant organism in the benthos, Oreogeton sp. was poorly represented in the leaves. Low orthophosphate concentration of the water and precipitation of calcium carbonate onto the leaves may have inhibited the biotic processing of leaves in Cabin Creek.

Processing of willow leaves in two suburban streams in Chrisrtchurch, New Zealand

“…Weight losses from leaching recorded in this study are similar to those reported by Dawson (1976) of 15% after 5 days for S. viminalis and by Mutch & Davies (1984) of 23% after 17 days for S. drummondiana. After the initial leaching period, breakdown of leaves held in 3 mm mesh bags was the result of microbial decomposition and invertebrate feeding.…”

“…Microbial decomposition of leaves in the present study was much faster than losses feported by Mutch & Davies (1984) for leaves in 0.25 mm mesh bags in a typical Rocky Mountain stream in Alberta. This was despite the fact that Mutch & Davies (1984) attributed some leaf processing to the presence of small invertebrates which penetrated the fine mesh. In contrast, breakdown of leaves in 0.15 mm mesh bags was very rapid in a stream in New England, Australia (Pidgeon & Cairns 1981).…”

Litter Breakdown in Mountain Streams Affected by Mine Drainage: Biotic Mediation of Abiotic Controls

“…Pristine reference sites in the present study had breakdown rates (mean breakdown coefficient k ϭ 0.013 d Ϫ1 ) that were similar to those measured previously for willow litter in Rocky Mountain streams (Short et al 1980, Mutch andDavies 1984). Sites affected by mine drainage usually had lower rates.…”

“…Similarly, Nelson (2000) showed that the rate of litter breakdown was not depressed at two sites affected by mine drainage that had concentrations of zinc Ͻ0.5 mg/L and still had shredding stoneflies. For example, invertebrates played a dominant role in litter decomposition in a mountain stream in Alberta, Canada (Mutch and Davies 1984). 11,No.…”

Eucalypt leaf decomposition in an intermittent stream in south-eastern Australia

“…While further studies report similar results for different leaf species (e.g. Iversen, 1975;Short et al, 1980;Mutch & Davies, 1984), other authors (e.g. Kaushik & Hynes, 1971;Gurtz et al, 1982;Allard & Moreau, 1986) suggest invertebrates are unimportant in leaf decomposition in streams.…”