APPLIED ISSUES Increasing litter retention in moorland streams: ecological and management aspects of a field experiment

Authors

  • MIKE DOBSON,

    1. School of Biological Sciences, Queen Mary & Westfield College (University of London), Mile End Road, London E1 4NS, U.K.
    Search for more papers by this author
    • *

      Department of Environmental and Geographical Sciences, Manchester Metropolitan University, John Dalton Building, Chester Street, Manchester, M1 5GD, U.K.

  • ALAN G. HILDREW,

    1. School of Biological Sciences, Queen Mary & Westfield College (University of London), Mile End Road, London E1 4NS, U.K.
    Search for more papers by this author
  • STUART ORTON,

    1. School of Biological Sciences, Queen Mary & Westfield College (University of London), Mile End Road, London E1 4NS, U.K.
    Search for more papers by this author
  • S.J. ORMEROD

    1. Catchment Research Group, School of Pure and Applied Biology, University of Wales College of Cardiff, Cardiff CF1 3TL U.K.
    Search for more papers by this author

SUMMARY

1. The retention characteristics of two moorland streams in mid-Wales were manipulated for 2 years by the addition of small traps which accumulated detritus. Leaf litter was also added to these essentially treeless streams at regular intervals to simulate natural inputs to a woodland stream.

2. Leaf traps retained a significantly higher biomass of detritus - both naturally occurring and added - than either the surrounding stream bed or unmanipulated reference sections. They also supported significantly higher numbers of nemourid, leuctrid, tipulid and elminthid insect larvae.

3. Among functional feeding groups, detritivores and, to a lesser extent, predators responded to increased detritus availability. Numbers of mayfly larvae were low in leaf packs, suggesting a negative effect of detritus aggregations on their numbers.

4. The taxa which responded positively to increased detrital biomass, particularly stonefly larvae, are known to be tolerant of low pH conditions, whereas those affected detrimentally are generally absent from acid waters. It is proposed therefore that increasing detrital inputs and litter retention in culturally acidified upland streams may serve to increase their invertebrate productivity.

Ancillary