Complementarity and other key criteria in the conservation of herb-rich forests in Finland

Abstract

Complementarity of the nature reserve network in southernmost Finlandwas examined using a simple heuristic algorithm and occurrence data of 75characteristic herb-rich forest vascular plant species in 126 protected and 120non-protected sites. Three different minimum sets were selected to represent 1,5, or 10 occurrences of each species. In each minimum set there weresignificantly more protected than non-protected sites. Thus, although efficiencyis not maximal in the existing reserve network, the network does provide arepresentative basis for the conservation of herb-rich forest plants. However,some deficiencies were also noticed, particularly new reserves in floristicallydiverse herb-rich forests along watercourses would supplement the existingreserve network. On the other hand, the growing concern over the shortcomings ofreserve selection studies using presence/absence data is echoed here, becausemany of the protected forests not included in the minimum sets harbour importantnature conservation values. With regard to the five biological reserve selectioncriteria (e.g. occurrences of threatened species) considered here, theperformance of the existing reserve network is rather good. However, examinationof five reserve design criteria revealed some deficiencies, particularlyvulnerability of many reserves to potential edge effects.