Close correlations exist between vegetation and the site-specific factors soil, water, climate, and cultivation. The causal relationships in this highly complex system cannot be explained with absolute precision solely by vegetation analysis as determinable changes in the vegetation cover may be based on different factor combinations. Plants are integrative bio-indicators the reactions of which can be categorized as quick and direct in comparison to the system "soil". Examinations are always performed over a long-term period as the factors of influence sometimes first manifest in the vegetation cover with a delay of several years. Vegetation analysis is based on the complete species inventory of a sample area in all those cases when the evaluation of the recordings is meant to uncover development tendencies at an early stage. Due to this natural unpredictability a method that can be standardized and, as far as possible, reproduced is contained in this standard, provided that the use of aggregated units, such as plant associations, is forgone during data collection, but such units are used for preliminary investigation and collection of extensive changes, if appropriate. This standard is used for the collection and evaluation of ecological data in order to: - carry out vegetation-ecological evidence preservation; - document nature conservation-motivated developments in the vegetation. In the event that agriculturalists or other interested parties initiate grievance procedures after years or decades, for example, due to alleged revenue loses or potential effects on the ecological functions of the area which is under evidence assurance, the recordings shall be repeated at exactly the same locations using the same methodology and at the same phenological point in time. The data are subsequently compared with the original recordings and analysed. Statements shall be made to what extent the discovered changes in the vegetation cover can be associated with the intervention performed. Specification of the amount of damage is not part of vegetation-ecological evidence preservation; it remains reserved to a specially appointed agricultural valuer. This standard has been prepared in NA 119-01-02-03 UA "Standortbeurteilung" ("Site assessment") at the Water Practice Standards Committee (NAW).