Abstract

We show that benthic freshwater communities of naturally acidic streams in boreal catchments differ depending on properties of the surrounding landscape. Although low pH usually is associated with negative impacts on species diversity and ecosystem function, here decomposition by insects and microbes as well as the abundance of leaf-eating insects were generally high at low pH and at humic sites influenced by mire-dominated compared with forest-dominated surroundings. Moreover, in situ growth experiments showed that the survival of two of the most abundant insect species was higher when they originated from mire-influenced sites, underscoring their tolerance to low pH. However, species diversity generally increased with pH and was greater at forest-influenced than at mire-influenced sites. Although less diverse, acidic and humic streams proved to be functional and supported distinct macroinvertebrate assemblages. Diversity and function in naturally acidic streams are apparently greatly influenced by the prevailing kinds of landscape-driven influences on water chemistry. In conclusion, well-known negative impacts of anthropogenic acidity on diversity and function may not apply to naturally acidic systems that are chemically and biologically heterogeneous.

Published in

Canadian Journal of Fisheries and Aquatic Sciences
2007, Volume: 64, number: 11, pages: 1563-1572
Publisher: NATL RESEARCH COUNCIL CANADA-N R C RESEARCH PRESS

SLU Authors

• Buffam, Ishi

  • Department of Forest Ecology, Swedish University of Agricultural Sciences
    

• Laudon, Hjalmar

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    
  • Department of Forest Ecology, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Environmental Sciences
Ecology
Fish and Aquacultural Science


Publication identifier

DOI: https://doi.org/10.1139/F07-118

Permanent link to this page (URI)

https://res.slu.se/id/publ/43474