THE DISTRIBUTION ATLAS OF PTERIDOPHYTES A ND PHANEROGRAMS OF SWITZERLAND (WELTEN AND SUTTER 1982) IN A RELATIONAL DATABASE - SPECIES NUMBERPER MAPPING UNIT AND ITS DEPENDENCE ON VARIOUS FACTORS
T. Wohlgemuth, THE DISTRIBUTION ATLAS OF PTERIDOPHYTES A ND PHANEROGRAMS OF SWITZERLAND (WELTEN AND SUTTER 1982) IN A RELATIONAL DATABASE - SPECIES NUMBERPER MAPPING UNIT AND ITS DEPENDENCE ON VARIOUS FACTORS, Botanica helvetica, 103(1), 1993, pp. 55-71
Wohlgemuth T., 1993. The distribution atlas of pteridophytes and phane
rograms of Switzerland (Welten and Sutter 1982) in a relational databa
se: Species number per mapping unit and its dependence on various fact
ors. Bot. Helv. 103: 55-71. The distribution atlas of pteridophytes an
d phanerograms of Switzerland (Welten and Sutter 1982) was digitized a
t the Swiss Federal Institute for Forest, Snow and Landscape Research
in Birmensdorf (CH). The data are stored in a relational data base, wh
ich is flexible enough to allow any kind of retrieval and analysis. Th
e floristic diversity and its dependence on various factors was analys
ed by comparing the species number per mapping unit. A relation could
be established between species numbers and the following factors: rang
e of altitude covered by the mapping unit, rock type, geographical reg
ion, and thoroughness of the mapping. Low species numbers were found i
n most of the mountainous areas in the Ticino consisting mostly of non
-calcareous rock, such as Gneiss. Analysis shows, that the species num
bers in the western parts of the country are on average lower than in
the eastern parts. The geographical regions with the highest floristic
diversity are the Valais, the Ticino, the Grisons and the eastern par
t of the Northern Alps. A link was found between the species number pe
r mapping unit known from herbarium specimens only and the nearest her
barium. The species number per mapping unit known from the literature
strongly depends on the quality of the Flora available.