Conversation so far:
What happened in 2005 for Maathai?
On 28 March 2005, Maathai was elected the first president of the African Union's Economic, Social and Cultural Council.
What did she accomplish as President?
appointed a goodwill ambassador for an initiative aimed at protecting the Congo Basin Forest Ecosystem.
Was this initiative successful?
CANNOTANSWER.
What did she do after her time on as President?
In June 2009, Maathai was named as one of PeaceByPeace.com's first peace heroes.
What earned her that title?
CANNOTANSWER.
How did 2011 wrap up for Maathai?
Maathai died on 25 September 2011.

Question: How did she die?
Self-contained rewrite: How did Maathai die?