New Zealand Journal of Marine and Freshwater Research abstracts
Bryophyte distribution patterns in relation to macro-, meso-, and micro-scale
variables in South Island, New Zealand streams
ALASTAIR M. SUREN
National Institute of Water & Atmospheric
Research Ltd
P. O. Box 8602
Riccarton, Christchurch, New Zealand
Abstract A broadscale survey of 118 streams was made
throughout New Zealand's South Island to establish relationships between
aquatic bryophytes and selected environmental variables. Bryophytes were found
in 95 of the streams examined, and covered large areas of the substratum (mean
cover of 17%, maximum cover of 86%). TWINSPAN analysis revealed the existence
of five sample groupings, of which one supported no bryophytes. Streams without
bryophytes typically flowed through developed catchments (pasture or pine)
composed of easily eroded rocks. Nutrient levels were high in these streams,
and low-flow events were also common. Streambed stability was low, reflecting
lack of stable bedrock and boulder substrata. TWINSPAN identified two major
groups of streams with bryophytes: those supporting mosses and those supporting
liverworts. These streams differed from those without bryophytes by having a
higher streambed stability, and fewer low-flow events. These two variables thus
appear fundamental in controlling aquatic bryophyte distribution patterns.
Flood events had no significant impact on these plants once they grew on stable
substrata. No differences in stream stability, or substrate composition, were
found between streams dominated by mosses and those dominated by liverworts.
Catchment geology, land use, water quality, and the number of high-flow events
differed between these streams, suggesting that these factors influenced what
type of bryophyte community occurred.
Keywords aquatic bryophytes; distribution; hydrology;
substrate stability; geology; land use; water chemistry
New Zealand Journal of Marine and Freshwater Research, 1996: Vol 30:
501-523
0028-8330/96/3004-0501 $2.50/0 (c) The Royal Society of New Zealand
1996
PDF file of entire paper: medium quality (1616K); (scanned from paper original: notes about this process)
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