Alvar Palmgren
| Alvar Palmgren | |
|---|---|
 |
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| Born | 28 April 1880 Finland |
| Died | 30 November 1960 (aged 80) |
| Nationality | Finland |
| Fields | botany, plant ecology |
| Institutions | University of Helsinki |
| Alma mater | University of Helsinki |
| Doctoral advisor | J.P. Norrlin |
| Author abbrev. (botany) | Palmgr. |
Alvar Palmgren (28 April 1880 – 30 November 1960) was a Finnish botanist and plant ecologist.
Palmgren studied botany at the University of Helsinki under professor J.P. Norrlin. He graduated (Fil.kand.) in 1906 and obtained his Ph.D. in 1914. He became docent of botany at the University of Helsinki 1916 and professor of botany at the same university in 1928 (from 1938, the first in the special Swedish-language chair of botany). He retired in 1950.
Palmgren worked as a systematic botanist with microspecies of Taraxacum, Hieracium and other genera. As an ecologist, he worked of the nature of plant communities. He supported the ideas of Henry Gleason on the individualistic behaviour of species in community assembly already from the 1920s. Palmgren wrote early accounts on the role of isolation and stochastic events in the distribution of species, while his contemporary biology was largely deterministic.
In the 1920s, Palmgren entered in a heated dispute with the Swiss botanist and phytogeographer Paul Jaccard over the interpretation of Jaccard's species-to-genus ratio. Palmgren had observed a decrease in species richness from west to east in the Åland Islands, his main geographical scene of scientific inquiry. He interpreted this as an effect of isolation from the Swedish mainland to the west, and the associated lower species-to-genus ratio as a random sampling effect. In contrast, Jaccard held that the lower species-to-genus ratio towards the east was an effect of decreased diversity in habitat conditions and increased competitive exclusion. The Swiss botanist Arthur Maillefer showed statistically that genera accumulate much faster than species and that therefore Paul Jaccard's biological explanation of the pattern was unnecessary since it could be fully explained as a statistical sampling effect. An analytical solution with the same result was provided by the Hungarian mathematician George Pólya. In essence, this disagreement were repeated by Charles Elton vs. C. B. Williams and again reiterated by Peter Grant and Daniel Simberloff in the 1970s.
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