B. Papp szerk.: Studia Botanica Hungarica 30-31. 1999-2000 (Budapest, 2000)

Papp, Beáta, Ódor, Péter; Erzberger, Peter: Preliminary data about the present Hungarian local populations of rare European bryophytes

The following is a specific example of a species in which case we have checked all known localities in order to establish its IUCN category in Hungary. Criteria of this are the following (IUCN 1994): A) Large decline: CR (Critically Endangered) = major population decline observed, estimated, inferred or suspected in the last 10 years or 3 generations, whichever is the longer, based on: 80% or more; EN (Endangered) = 50% or more, VU (Vulnerable) = 20% or more. It is not applicable in this case. Declined, but the decline occurred mostly over 10 years ago. B) Restricted area of occupancy, few localities: CN = Recently recorded within only one 10 km x 10 km square and found in only one locality or the populations are severely fragmented. It means small subpopulations that are all more or less isolated. - EN = Recently recorded in five or fewer 10 km x 10 km squares and found in two to five localities or the populations are severely fragmented. - VU = Recently recorded in ten or fewer 10 km x 10 km squares and found in ten or fewer localities or the populations are severely fragmented. Fissidens arnoldii has been recorded recently from three 10 km x 10 km squares and it has three localities. It corresponds to the EN category. C) Small population and decline: Small population: CR = fewer than 250 mature individuals; EN = fewer than 2500 mature individuals; VU = fewer than 10,000 mature individuals. In the case of Fisidens arnoldii we take a leafy shoot as one individual. About 60-80 individuals of Fissidens arnoldii can be counted in a 1 cm x 1 cm square. It frequently forms about 5 cm x 5 cm patches. It means, that at one locality for example at the Deszkametsző malom near Bánd village the size of the population is more than 5,000 individuals. The total population size in Hungary at 3 localities is probably over 10,000 individuals. The species does not correspond to the above mentioned categories, but it is close to qualifying as vulnerable (VU). The species can be put into the Lower risk (LR) category, into the near threatened (nt) subcategory. D) Very small or restricted populations: CR = fewer than 50 mature individuals; EN = fewer than 250 mature individuals; VU = fewer than 1,000 mature individuals (subcriterion Dl) or an area of occupancy less than five 5 km x 5 km squares, or 4 or fewer localities (subcriterion D2). According to this criteria our species corresponds to the vulnerable (VU) category according to the subcriterion D2.