Arnold Engler, January 29 1869 (Stans, Switzerland) – July 15 1923
Arnold Engler completed secondary school in Zug and Luzern and then studied forestry at the Polytechnikum (ETH) in Zurich from 1887 to 1890. After teaching practice and brief practical activity in the canton of Graubünden, he was elected head forester of the canton of Nidwalden in 1893, but only four years later - barely 28 years old - he was appointed by the Federal Council to the chair of silviculture at the Polytechnikum Zurich, and on 1 January 1902 he was also appointed head of the forestry research institute (EAFV). Engler earned himself the highest reputation as a forest farmer in the field of seed provenance; but for hydrologists he is known for first analyses of the two pioneer runoff stations in the two first-order catchments Sperbelgraben and Rappengraben (Emmental, Switzerland). He was awarded an honorary doctorate by the University of Zurich in 1918 and the University of Soil Culture in Vienna in 1921 for his outstanding achievements. After a serious illness, Engler died on 15 July 1923, at the age of 54.
As director of EAFV, Engler was responsible for the first systematic runoff measurements in small forested catchments that his predecessor C. Bourgeois had set up in 1900 in the Sperbelgraben und Rappengraben in the Emmental to assess the influence of forests on the natural runoff formation. Both experimental areas, the Sperbelgraben, which was completely forested, and the Rappengraben, which was only sparsely forested, were generously equipped with rain gauges, thermometers, water level gauges, etc. Special attention was paid to heavy rain storms. After more than 15 years Engler published the first results of these longterm measurements in a book with more than 600 pages (Engler 1919). For the foresters of that time the report was a breakthrough as it demonstrated the positive effect of forests to mitigate floods. Also from the point of view of soil science, Engler's work represents a milestone. Engler had recognized that the hydrology of the investigated catchments could not be interpreted meaningfully without knowledge of the pedological conditions. From 1911 to 1917, a total of 778 soil analyses were carried out in both experimental catchments. In addition, the evaporation of water was determined in relation to a free water surface. The soil investigations revealed that in many cases hardly any suitable methods were available or that the results could not be adequately evaluated. At the end of his report, Engler therefore pointed out the need for more soil-physical investigations. Engler was a forest farmer and not a soil scientist. However, his merit for soil science and in particular for soil physics was to have recognized the necessity of including soil-physical measurements for the understanding of hydrological processes in forest ecosystems and their silvicultural significance.
The main lecture hall of the Swiss Federal Research Institute WSL (Birmensdorf) is still named after Arnold Engler (“Englersaal”)
Hans Sticher, 2001, BODENKUNDE UND BODENKUNDLER IN DER SCHWEIZ 1855 bis 1962 Mit einem kurzen Rückblick auf die Vorgeschichte. BODENKUNDLICHE GESELLSCHAFT DER SCHWEIZ SOCIETE SUISSE DE PEDOLOGIE DOKUMENT 11 ISBN 3 260 05452 9 Juris Druck und Verlag Dietikon. (Link: http://www.soil.ch/cms/fileadmin/Medien/BGS_Fachgesellschaft/BGS_Dokumente/BGS_Dokument_11.pdf)
Engler, A. (1919): Studien über den Einfluss des Waldes auf den Stand der Gewässer. Mitt. Schweiz. Anst. forstl. Versuchsw. 12: 1 -626.