Abstract
Regional populations of two terrestrial Utricularia species were studied. Small oligotrophic spring-fed hillside marshes are the habitat of these species in the region studied. The probability that a habitat patch was occupied by a species was positively correlated with the local patch density in both species. The regional population was a metapopulation in the strict sense. The critical patch density to prevent extinction (plants appeared in 90% of habitats) was 3.4 patches within a 500-m radius in U. racemosa (4.3 km^<-2>) and 3.1 patches within a 100-m radius in U. bifida (99 km^<-2>). The number of patches within an effective spatial scale was similar (3-4 patches) despite the large difference in absolute density (4.3-99 km^<-2>). To conserve terrestrial Utricularia in this region, groups of marshes should be conserved.
