Freshwater Umbrella Research 2004-7

WP 3: Nitrate leaching

Task 3.4 — Moss survey of AWMN sites

A recently submitted paper (Curtis et al.) has demonstrated the close correspondence between increasing nitrate leaching and declining biomass of moss + lichen with increasing N deposition. While the data are restricted to just four sites (Mharcaidh, Gwy, Scoat, Etherow) they strongly suggest a decline in mosses in response to elevated N (and S) deposition. Since mosses and lichens are the most efficient biological compartment for retaining deposited N and converting it into recalcitrant organic N, there could be a causative link between decline in mosses and increase in nitrate leaching. In this Task the hypothetical link will be tested for sites with existing nitrate leaching data across the UK Acid Waters Monitoring Network by measurements of moss biomass at up to 20 randomly selected points in each of the 22 AWMN catchments.