He was a leading figure in the Uppsala school of phytosociology–the study of groups of species of plants that are usually found together–and is recognised for his role in advancing this field of science and for mentoring future lichenologists.

During the expedition, Du Rietz and his wife researched the vegetation in New Zealand, Australia, and Java, focusing on mountain lichens and their potential as bioindicators for environmental conditions.

They collected around 3000 specimens, contributing significantly to the study of bipolar lichens and forest ecology, despite challenges in processing all the samples upon return to Sweden.

[2] He was the second son of the CEO of Stockholms Benmjölsfabrik AB [sv], the engineer Hjalmar Du Rietz and Charlotta Sofia Mathilda (born Kullman).

The seventeen-year-old who registered at Uppsala University developed a varied interest in outdoor botany, especially in lichens and coastal areas, passions that he maintained throughout his life.

The dissertation was translated into German and printed in Vienna for economic reasons, reflecting the scientific language preference in the Nordic countries at the time.

[7] Du Rietz was also the leader of the biological geological work at Abisko Scientific Research Station, and general secretary of the international plant geographical excursion through Scandinavia in 1925.

Du Rietz undertook several study trips within and outside Sweden, scientific expeditions to New Zealand and Australia and in his research mainly devoted on plant sociology and lichenology.

Sjörs regarded these events as the fourth pinnacle in Du Rietz's professional career, following his doctoral dissertation, the 1925 field trip, and achieving his professorial qualifications.

[8] In 1926–27, Du Rietz and his wife conducted a research trip to New Zealand, including its sub-Antarctic islands, with visits to a large part of Australia and Java.

One of Du Rietz's research objectives was to determine whether a detailed study of mountain lichens could increase the recognised Arctic elements within New Zealand's flora.

[14] This research intended to identify which forest tree species could replenish areas cleared by sawmilling,[15] the fear of a possible wood shortage was an environmental concern causing widespread anxiety in New Zealand at that time.

[16] Du Rietz's New Zealand itinerary included the Tararua Mountains, montane research stations operated by Canterbury College, Hokitika, Mount Cook, and the fjords of northwest Otago.

[14][13] The local newspaper, The Evening Post, reported Du Rietz's visit, and described him as "virtually the founder of the important Swedish school of ecology" and "probably the foremost expert regarding lichens".

His dedication to the field and his students impacted the direction and development of plant geographical studies in Sweden, leaving a legacy in both academic and conservation communities.

As a member of the Swedish Academy of Sciences' nature conservation committee, he organized surveys of the shores of the lakes and river stretches that were threatened by the ongoing expansion of hydroelectric power in Norrland.

[8] When Du Rietz, as emeritus, turned 70, many of his former students gathered to write a 300-page collection of papers titled The Plant Cover of Sweden (Acta Phytogeographica Suecica 50, 1965), recognising him as the foremost explorer of Swedish vegetation.

This compilation served not only as an acknowledgment of Du Rietz's impact on phytosociology and botanical studies in Sweden but also aimed to provide an accessible resource to a global audience, reflecting the international reach and influence of his work.

In 1964, Carroll William Dodge proposed the subgenus Durietzia of genus Lobaria, writing "I take great pleasure dedicating this to my friend Einer Du Rietz, who first pointed out to me some of the physiologic and ecologic implications of the rimose cortex in species of Parmelia, and argued for its recognition as a taxonomic character".