His work allowed for the production of a vegetation map of France at a scale of 1/200 000 (completed after his death by the service of the CNRS, but which he had created and directed) and many similar projects in other countries.

His work led to many advanced phytogeographic tools such as the xerothermic or Gaussen Index, and the "ombrothermic diagram [fr]".

He was also responsible for the creation of the Arboretum de Jouéou in 1922, and for the strength and reputation of teaching and research in botany at the University of Toulouse.

Henri Gaussen spent his entire career as a professor at Toulouse, where he was also in 1958 elected as a "mainteneur" (council member) of the Académie des Jeux floraux.

Having accumulated an impressive number of personal photographs, he donated his collection to the archives of the department of Haute-Garonne, where they can still be viewed.