Question: Herb-rich patches are biodiversity hotspots for vascular plants in boreal forests. We ask: Do species occurrences on herb-rich patches show a non-random, nested structure?; Does patch size relate to richness of edaphically demanding and red-listed species?; Does a set of small patches support more edaphically demanding and red-listed species than a few large patches of the equal area?
Location: Eastern Finland (63°04′N, 29°52′E), boreal vegetation zone.
Data: Vegetation mapping of 90 herb-rich sites, varying from 0.05 to 6.93 ha in size and belonging to six different, predetermined forest site types.
Results: Using the RANDNEST procedure, only one site type showed a significantly nested pattern, and patch area was not related to “nestedness” in any of the site types. The number of edaphically demanding and red-listed plant species was positively correlated with a patch size in three forest site types. In all site types, a set of small patches had more edaphically demanding and red-listed species than did a few large patches of the equal total area.
Conclusions: For conservation, it is essential to protect representative sets of different herb-rich forest site types because flora varies between the site types. Within herb-rich forest site types, several small areas may support representative species composition. However, successful conservation requires thorough species inventories, because of the high level of heterogeneity between the herb-rich patches.