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The effect of catchment liming on bryophytes in upland Welsh streams, with an assessment of the communities at risk
Author(s) -
Wilkinson S. M.,
Ormerod S. J.
Publication year - 1994
Publication title -
aquatic conservation: marine and freshwater ecosystems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.95
H-Index - 77
eISSN - 1099-0755
pISSN - 1052-7613
DOI - 10.1002/aqc.3270040403
Subject(s) - bryophyte , streams , abundance (ecology) , ecology , drainage basin , environmental science , biology , geography , computer network , cartography , computer science
Abstract The effects of catchment liming, used to restore acidified streams, are still only partially known. In particular, the impact on aquatic bryophytes remains unappraised. Six upland streams were surveyed for aquatic bryophytes from 1987–93, and three of their catchments limed experimentally in 1987–88 so that the resulting changes in the abundance and distribution of common bryophyte taxa could be assessed. An additional nine streams were surveyed during 1987–89, 1992 and 1993 using the same methods to give a wider indication of the bryophyte communities in streams where liming might occur. Twenty‐nine bryophyte species were recorded from the wetted margins of these 15 upland streams. Percentage cover by individual species varied markedly, and was highest in Nardia compressa (up to 71%). Cover by most other species was limited to less than 5%. Total bryophyte cover, and cover by Scapania undulata fluctuated from year to year so that no responses to liming could be detected. However, cover by Nardia compressa declined significantly from 39% ± 21% SD to 5% ± 2% SD in treated streams following lime addition. Reference streams showed no such change, and no other taxa increased in abundance to replace the lost Nardia in the 5 years after liming. Changes of this type, and their possible ramifications for invertebrates, will have to be considered where catchment liming is planned.