The scientific practice and theory of ecology in the German-speaking world arose simultaneously yet independently of each other in different places and in relation to different subjects. The new disciplining perspective took in lakes and fish ponds as well as native forest, heath and mountain landscapes, though it also included the flora and fauna of tropical and arctic regions. “German-speaking world” refers here not so much to an area determined by its political or natural borders but rather by its linguistic boundaries. A lively exchange of publications, objects and individuals took place within this scientific world. Cities and regions belonging to different spheres of political influence were a part of this Sprachraum, which encompassed Zurich, Vienna, Prague, Budapest and Berlin, as well as Bohemia, Silesia and Prussia, the Rhineland and the Valais. Perfect examples of the commonplace exchanges that took place in what we call the “German-speaking world” of that time were the botanists Simon Schwendener and Gottlieb Haberlandt, who were decisive for the formation of physiological plant ecology (see below). Schwendener was born and educated in Switzerland and spent most of his working life in Germany (Tübingen and Berlin; prior to that in Basel, Switzerland); Haberlandt was born in Hungary, educated in Austria and worked for most of his life in Austria (Vienna and Graz), though at times also in Germany (Tübingen and Berlin). So if – for the sake of brevity – we speak of “German” ecology in this chapter, we mean this region as delimited by the common use of the German language as a means of communication.