After graduating he worked as a professional in Talca in the pharmacy of Guillermo Kuschel, the distinguished trade union and industrial director, one of the founding partners of the Laboratorio Geka.
Later Gunckel returned to Valdivia to serve as the pharmaceutical head of the Railroad Zone IV, work which was later suppressed.
Gunckel moved to Corral, where he started a pharmacy but the near-virgin landscape that surrounded this port, rich in forests, ferns and grasses, made him a collector of plant specimens.
In 1946 he became the president of the School of Forestry Engineers (Escuela de Ingenieros Forestales), the first establishment of the specialty created in Chile.
On May 1, 1950 he moved to Santiago to fill the botany chair in the Facultad de Farmacia, which was directed by the professor Juan Ibáñez, who performed duties for UNESCO and thus was frequently travelling.