Making them visible and usable — vegetation‐plot observations from Fennoscandia based on historical species‐quantity scales

Abstract

Abstract Aims Present‐day large‐scale and plot‐based vegetation analyses contribute to the transnational characterization and interpretation of biodiversity patterns and to habitat typologies which are important for planning, monitoring and decision making in nature conservation. Many historical vegetation surveys applied cover abundance, relative occurrence or density scales (species‐quantity scales) that are nowadays poorly known and consequently disregarded or misinterpreted. Therefore, it is worthwhile to put effort into making them compatible with the datasets sampled using mainstream methods. Within Europe, this especially applies to historical data from Fennoscandia. Here, we aim to propose how to transform the species‐quantity scales frequently used in Fennoscandia into percentage cover scales, based on the conversion of their individual grades. Study area Fennoscandia, including Norway, Sweden, Finland and the Fennoscandian part of Russia (Republic of Karelia, Karelian Isthmus, Murmansk Region). Methods and results We inventoried Fennoscandian vegetation‐plot studies and identified that the most frequently applied species‐quantity scales were those of Norrlin, Hult–Sernander and Drude. We reviewed the definitions and applications of these scales in the literature and, if not available, calculated hypothetical species covers to approximate realistic conversions to the percentage scale. As a result, we propose alternative ways of conversion of the individual scale grades to mid‐percentage cover values. Conclusion Historical vegetation plot data from Fennoscandia can be used as quantitative information for vegetation research if their grades are consistently transformed into percentage cover values using the proposals presented in this paper.