DOI: 10.5285/c121f915-6f64-4b74-aa24-cd70708a29d2
title: Leaf litter decomposition in Welsh upland rivers in response to organic matter addition (2012 - 2013)

description: These data are leaf litter decomposition rate in eight Welsh upland rivers with contrasting land-use, moorland and exotic conifer, in response to riparian deciduous leaf addition. Eight sampling reaches were chosen at two sites, Llyn Brianne (4 reaches) and Plynlimon (4 reaches). The experiment consisted of adding deciduous leaves to half of the reaches whilst the other half were maintained as a control (no addition of deciduous leaves). To characterise the leaf litter decomposition of the studied streams, onion bags were placed during November 2012, and then collected during January 2013 (before deciduous leaf addition) and March 2013 (after deciduous leaf addition) in each sampling reach. 

The main goal of this survey was to examine how aquatic biodiversity and litter decomposition respond to leaf addition in moorland and conifer forested rivers. Dr Isabelle Durance was responsible for organising the surveys, Dr Hugh Feeley, Dr Dan Perkins and Marian Pye were in charge of collecting, processing and sorting the samples. The work was carried out under Diversity in Upland Rivers for Ecosystem Service Sustainability (DURESS) project (Grant reference NERC NE/J014818/1). DURESS was a project funded by the Natural Environment Research Council (NERC) Biodiversity and Ecosystem Service Sustainability (BESS) programme. 

description: Each stream was divided into an upstream control zone and a downstream experimental zone. Samples of leafs were collected on each sampling occasion. Deciduous leaves were added directly to the stream and by fixing 'Onion bags' of leaves the stream bed and bank. Samples were collected two occasions, January (3-16/01/2013), and March (11-14/03/2013) in all the streams in both the upstream reference zones and downstream experimental zones. 

In early November 2012, 48 replicate litter bags (24 per reference zone and 24 per experimental zone) of two mesh types, fine and course filled with air dried deciduous leaves were secured in pairs to randomly distributed metal poles each of the study streams. The mesh bags were then covered with cobbles to facilitate biological colonisation. At the end of the 'before' treatment half the litter bags or 6 fine and 6 coarse mesh litter bags were removed gently from both the reference and experimental study zones within each stream. At the same time 6 new fine mesh and 6 new coarse mesh litter bags were added to each pole to measure the decomposition during the 'after' manipulation period. These bags were left until the end the experimental period. At this point all of the remaining litter bags were removed. 

Directly upon collection, all litter bags were preserved in 70 per cent ethanol on site, within individual clear polystyrene bags, marked with an identifying code and transported back to the laboratory for processing. Once in the laboratory the leaf material from each litter bag was rinsed carefully under tap water under a fine sieve and air dried at room temperature. All macroinvertebrates were separated from the contents of each litter bag.

Data was exported to a comma separated values files for ingestion into the Environmental Information Data Centre (EIDC).