Survey of giant hogweed, Japanese knotweed and Himalayan balsam on 5 major Lothian rivers, 2003/04

Quality Control

Highland Ecology, ecological consultants with experience of vegetation survey and alien plant survey, were commissioned to carry out the work. Many records were for transects; these have been reduced to 100 m point locations for the purposes of mapping. Approx. 39 records from the River Almond catchment were excluded due to errors in processing their grid-references, so the Almond is under-represented in the data.

Method steps

1. Initial field survey was undertaken in September/October 2003 with walked surveys carried out over rivers and their main tributaries. In mid-October, shortly after the first frost and subsequent leaf/flower loss by key species, field work was halted in order to eliminate error in locating species which were harder to see. The survey was resumed and completed in June 2004. Where access was restricted either topographically or due to private gardens, these sections were noted or viewed using binoculars. Some lengths of river were not seen for various reasons, most commonly steep or dense woodland and private housing and grounds. Where this happened grid references of the limits of these were recorded. Some sections were, for similar reasons, only seen intermittently and again the reason recorded. A hand-held GPS unit was used to increase accuracy in obtaining location grid references for stands. However it was not always possible to take a reading due to trees blocking a clear view of the sky.