Rapport nr 94: Storfjärilsfaunan på Husö biologiska station 1985-1996
ÖSTMAN, M (1997)
ÖSTMAN, M
Åbo Akademi, Husö biologiska station
1997
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Julkaisun pysyvä osoite on
https://urn.fi/URN:ISBN:952-12-0054-5
https://urn.fi/URN:ISBN:952-12-0054-5
Tiivistelmä
The macrolepidopteral fauna in the area of Husö Biological Station, Åland Islands, SW Finland, was studied by means of fight traps, bait catches and visiual observations in 1985-95. The study area is situated in the inner archipelago zone and it is dominated by dry meadows, cultivated fields and decidous forests. The investigation is the first one to deal with long-term variations of the special lepidopteral fauna of the Åland Islands. In 1993-95 the fight trapping was a part of the Finnish Moth Monitoring Scheme, which in 1995 comprised 77 observation sites distributed over all parts of the country.
A total of 496 species were observed and 426 species were estimated to betong to the local fauna of the study area, the rest being considered in-flyer species. The number of species and alpha-diversity were of the same magnitude of order as those at mast observation sites in S Finland.
The fauna was dominated by species belonging to culture biotopes. 19 of the observed species have a distribution in Finland limited to the SW archipelago. 9 species are considered threatened in Finland ("Red Book species").
In the light trap material from 1985-95 the species abundances followed a log-normal distribution. A hypothetical maximum number of species was calculated at 433. The 20 most abundant species constituted 4,8 % of the total number of species.
The number of specimens captured per year and light trap as well as the number of species of which a second generation occured, were significantly related to the total ETS at the end of the flight season. An ETS value of about 430 °C was required until 50 % of the species had begun their flight.
The number of species showing an obvious increasing or decreasing trend in 1985-95 was estimated at 27 and 28, respectively. The decrease of the latter ones is in most cases explained by cold early summers in the 1990s. 4 species established new populations in the study area, whereas two species of the original local fauna disappeared during the study period.
A total of 496 species were observed and 426 species were estimated to betong to the local fauna of the study area, the rest being considered in-flyer species. The number of species and alpha-diversity were of the same magnitude of order as those at mast observation sites in S Finland.
The fauna was dominated by species belonging to culture biotopes. 19 of the observed species have a distribution in Finland limited to the SW archipelago. 9 species are considered threatened in Finland ("Red Book species").
In the light trap material from 1985-95 the species abundances followed a log-normal distribution. A hypothetical maximum number of species was calculated at 433. The 20 most abundant species constituted 4,8 % of the total number of species.
The number of specimens captured per year and light trap as well as the number of species of which a second generation occured, were significantly related to the total ETS at the end of the flight season. An ETS value of about 430 °C was required until 50 % of the species had begun their flight.
The number of species showing an obvious increasing or decreasing trend in 1985-95 was estimated at 27 and 28, respectively. The decrease of the latter ones is in most cases explained by cold early summers in the 1990s. 4 species established new populations in the study area, whereas two species of the original local fauna disappeared during the study period.