In terms of Part IVA of the Conservation (Natural Habitats, &c) Regulations 1994 an appropriate assessment is required where a land use plan is likely to have sognificant effect on a European site (as defined in Regulation 10) in Great Britain or a European offshore marine site (either alone or in combination with other plans or projects).  In terms of the Regulations land use plan means a strategic development plan or local development plan or supplementary guidance as provided for in Part II of the Town and Country Planning (Scotland) Act 1997. 

For guidance on Appropriate Assessment then authorities may wish to consider Interim Guidance published by the Scottish Ministers on Assessing Development Plans in Terms of the Need for Appropriate Assessment: http://www.scotland.gov.uk/Resource/Doc/127532/0030555.pdf.