Christen C. Raunkiær

Christen C. Raunkiær

c. 1930
Born 1860
Lyhne, Denmark
Died 1938
Copenhagen
Nationality Danish
Fields plant ecology, botany
Institutions University of Copenhagen
Alma mater University of Copenhagen
Doctoral advisor Eugen Warming
Doctoral students Johannes Iversen
Carsten Olsen
Known for Raunkiær life forms, Raunkiær's frequency law
Author abbrev. (botany) Raunk.

Signature

Christen Christensen Raunkiær (29 March 1860 – 11 March 1938) was a Danish botanist, who was a pioneer of plant ecology. He is mainly remembered for his scheme of plant strategies to survive an unfavourable season ("life forms") and his demonstration that the relative abundance of strategies in floras largely corresponded to the Earth's climatic zones. This scheme, the Raunkiær system, is still widely used today and may be seen as a precursor of modern plant strategy schemes, e.g. J. Philip Grime's CSR system.

Life

He was born on a small heathland farm, named Raunkiær, in Lyhne parish in western Jutland, Denmark. He later took his surname after it. He succeeded Eugen Warming as professor in botany at the University of Copenhagen and the director of the Copenhagen Botanical Garden, a position he held from 1912 to 1923. He was married to the author and artist Ingeborg Raunkiær (1863–1921), who accompanied him on journeys to the West Indies and the Mediterranean and made line drawings for his botanical works. They divorced in 1915, the same year as their only son Barclay Raunkiær died. Raunkiær later married the botanist Agnete Seidelin (1874–1956).

Raunkiær's research axiom was that everything countable in nature should be subjected to numerical analysis, e.g. the number of male and female catkins in monecious plants and the number of male and female individuals in dioecious plants. Raunkiær also was an early student of apomixis in flowering plants and hybrid swarms. In addition, he studied the effect of soil pH on plants and plants on soil pH, a work his apprentice Carsten Olsen continued.

After his retirement, C. Raunkiær made numerical studies of plants and flora in the literature ("The flora and the heathland poets", "The dandelion in Danish poetry", "Plants in the psalms"). In these studies, he applied strict quantitative criteria, like in his ecological studies. For example, he defined a poet as a person who has written 1,000 or more lines of verse.

Life form spectra

Raunkiær's life forms: 1. Phanerophyte.
2-3. Chamaephytes.
4. Hemicryptophyte.
5-6. Geophytes (cryptophytes).
7. Helophyte.
8-9. Hydrophytes.
Therophyte (annual, surviving as seed) not shown

Raunkiær devised a system for categorising plants by life-form as a way of ecologically meaningful comparison of species and vegetation in regions having different floras.

Raunkiær compared statistically local life form spectra (relative abundance) with the world average, which he called "the normal spectrum" (Raunkiær 1918 – see below). Thereby, he devised the first null model in the history of ecology. Raunkiær was a keen naturalist, who described the flora and funga of Denmark, the Virgin Islands, Tunisia, and other countries. In contrast to many contemporary naturalist, however, he strongly promoted quantitative and numerical approaches and experimentation. He devised a method to quantify the abundance of plants in vegetation as frequency in subplots and used it for quantitative studies of a range of plant communities.

Raunkiær's law

When plotting the number of species in a plant community that fell in each 20-percentile frequency class from very frequent, i.e. numerically dominant, to very infrequent, Raunkiær discovered that most species were either very common or very rare. This came to be known as "Raunkiær's law" and is related to R. A. Fisher's logseries distribution and to Frank W. Preston's lognormal distribution of the number of individuals of each species in a community.[1][2] The significance of his idea was, however, disputed already by some of his contemporaries.[3]

Leaf size in plant geography

As a further experiment in characterizing plant communities, Raunkiaer devised a numerical scheme based on leaf size classes and leaf type (simple or compound) that was extended by L. J. Webb[4] and is used as a way to classify forest types more simply than by lists of component species.[5]


Raunkiær in 1896

Scientific works of C. Raunkiær

Works on C. Raunkiær

References

  1. ↑ Preston, F.W. (1948) The commonness, and rarity, of species. Ecology 29, 254-283.
  2. ↑ Papp, L. & Izsák, J. (1997) Bimodality in occurrence classes: a direct consequence of lognormal and logarithmic series distribution of abundances – a numerical experimentation. Oikos 79, 191-194.
  3. ↑ Gleason, H.A. (1929) The significance of Raunkiaer's law of frequency. Ecology 10, 406-408.
  4. ↑ Webb, Leonard James (1959), "A Physiognomic Classification of Australian Rain Forests", Journal of Ecology 47 (3): 551–570, doi:10.2307/2257290
  5. ↑ Mesophyll rainforests of the wet tropics bioregion (PDF), wettropics.gov.au, retrieved 13 December 2015
  6. ↑ "Author Query for 'Raunk.'". International Plant Names Index.

External links

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