Josias Braun-Blanquet and the Sociology of Plants

Raunkiaer based his system on the way plants have adapted to climate. Other botanists were using a similar approach to classify large units of vegetation, and one of the most influential was the German botanist and plant geographer August Grisebach. Other European plant ecologists developed Grisebach's ideas. This led to the emergence of phytosociology as the study of plant communities. The foremost phytosociologist was the Swiss ecologist Josias Braun-Blanquet (1884–1980). Braun-Blanquet assembled a team of biologists who came to be known first as the Zurich School of Phytosociology, and from 1930 as the Zurich-Montpellier School of Phytosociology. The change of name reflected the team's move from Zurich, Switzerland, to Montpellier, France, where Braun-Blanquet had been appointed director of the newly established International Station for Alpine and Mediterranean Botany, at Montpellier. The institution's French name is Station Internationale de Geobotanique Mediterraneenne et Alpine. This long name is usually abbreviated to SIGMA, and the Zurich-Montpellier approach to phytosociology—which continues to thrive—is sometimes known as Sigmatism.

In 1928 Braun-Blanquet published a book entitled Pflanzensoziologie (Plant sociology), based on his studies of the plant species he had found on Mount Aigoual in the Cevennes region of France. The book proved highly influential, and he revised it for its third edition in 1964. In his book Braun-Blanquet set out a method for classifying plant communities. He and his colleagues began developing and applying this scheme at the University of Zurich in Switzerland, and from 1930 at Montpellier. The method they devised began by surveying an area to identify the most characteristic species among its vegetation. The characteristic species indicated the type of environment, and that species together with the other plants in the area constituted a releve. Releves were then ranked hierarchically according to their geographical extent, with a phytosociological class occupying the largest area. The ranks in the hierarchy were identified by adding a specified ending to the stem of the name of the characteristic genus.

Josias Braun-Blanquet was born as Josias Braun at Chur, Switzerland, on August 3, 1884. He trained to be a shopkeeper while studying the plants around his home in his free time. The experience he gained observing the local flora allowed him to find employment from 1905 to 1912 as an assistant to the Swiss plant ecologists Heinrich Brockmann-Jerosch, Eduard Rubel, and Carl Schroter. From 1913 to 1915 he studied at the University of Montpellier under the French botanist Charles Flahault (1852–1935). In 1915 Braun received his Ph.D. from the University of Montpellier. The same year he married a fellow student Gabriella Blanquet. Following his graduation, Braun-Blanquet as he then was became an assistant to Rubel until 1922, when he obtained the post of lecturer at the Cantonal Technical High School in Zurich. He remained at Zurich until 1926, during which time he formed the Zurich School. In 1926 he returned to live in Montpellier, earning his living as a private teacher. He was appointed the first director of SIGMA in 1930 and remained in that position until his death at Montpellier on September 20, 1980.