Pierre Dansereau CC GOQ FRSC (October 5, 1911 – September 28, 2011)[1] was a Canadian ecologist from Quebec known as one of the "fathers of ecology".

In 1961 he returned to the United States as the assistant director of the New York Botanical Garden and as a professor of botany and geography at the Columbia University.

From 1972 until 1976 he was the Director of the Research Centre for Sciences and the Environment at the Université du Québec à Montréal (UQAM).

He was the subject of a 2001 documentary An Ecology of Hope by his cousin, Quebec filmmaker Fernand Dansereau.

[2] On September 28, 2011, Pierre Dansereau died, one week before his 100th birthday, after 76 years of marriage, and three months after his wife (a painter) became a centenarian — they had no children.