American plant physiologist and ecologist. Born in Liberty, Indiana, Daniel Trembly MacDougal was a leading expert on desert ecology and one of the first botanists to study chlorophyll. His knowledge of desert plants and their environments began in the summers of 1891 and 1892 when he was employed by the United States Department of Agriculture to collect specimens in Idaho and Arizona. In 1893, he joined the faculty of the University of Minnesota as a lecturer in plant physiology, which he had studied at DePauw and Purdue Universities. He obtained a leave of absence for the year 1895-1896 to visit the leading plant physiology laboratories in Europe, and as a result of his research with Wilhelm Pfeffer at Leipzig, he published a paper entitled "The Curvature of Roots" (1897) that earned him a PhD from Purdue even though he was not in residence.
In 1899 he left his teaching position in Minneapolis to become Director of Laboratories at the New York Botanical Garden; he was promoted to Assistant Director in 1904. An early proponent of the mutation theory of Hugo de Vries, whose California lectures he edited for publication in 1905, MacDougal established an experimental garden in the grounds of the botanical garden as early as 1902 to study mutations in cultures of evening primrose, apparently the first experimental garden in the United States to be devoted to studies of this kind. He also continued to conduct field work in the American Southwest.
Beginning in winter 1905, he and Godfrey Sykes undertook a long-term study of the Salton Basin and Colorado Delta region, which he visited at least twice each year for a number of years. Soon after his arrival at the New York Botanical Garden in 1899, he and F.V. Coville journeyed to Tucson on behalf of the recently founded Carnegie Institution to select a location for a projected desert laboratory. MacDougal was appointed as its first director when it opened in 1906, and also of the Carnegie Institution's Department of Botanical Research in Washington, positions he held until his official retirement in 1928. In Tucson, and later also at the Coastal Laboratory, which he established at Carmel in 1909, he and his staff conducted research in the fields of plant physiology, ecology, and plant geography.
MacDougal was especially interested in the climatological and auxometric aspects of physiological ecology, particularly plant-water relations. Imbibition and swelling, growth and enlargement were favourite topics. Already at New York he had invented and brought into use recording instruments such as the MacDougal dendrograph, which records volume changes in tree trunks to aid this kind of research. Besides plot studies and laboratory experiments, he organised field trips into areas of ecological interest in Arizona, southern California, and northwestern Mexico. An account of one of these expeditions to Mexico, The Camp-Fires on Desert and Lava: Exploring the Unknown Pinacate Region of Northwestern Mexico (1908), was published by the field naturalist William Temple Hornaday, who accompanied MacDougal and Sykes on the expedition.
In 1912, again teamed with Sykes, MacDougal crossed the Libyan Desert. MacDougal helped to found the Ecological Society of America, one of the many scientific societies in which he was active, and was elected as honorary president of the International Botanical Congress in Stockholm in 1950. In 1956 he became the first recipient of the New York Botanical Garden's Certificate of Distinguished Service.
Sources:
1939, "Daniel Trembly MacDougal: Pioneer Plant Physiologist", Plant Physiology, 14(2): 191-202.
