Wangari MaathaiWangari Maathai.Photo: Scott SchumacherWangari Maathai, winner of the Nobel Peace Prize in 2004, passed away on Sunday at the age of 71. She was the first African woman to win the prize, and the first person to win for environmental activism. She died in a hospital in Nairobi, Kenya, while undergoing treatment for ovarian cancer.

Maathai gained worldwide recognition for founding the Green Belt Movement, as explained on the group’s website:

In the 1970s, Professor Maathai became active in a number of environmental and humanitarian organizations in Nairobi … Through her work … she spoke to rural women and learned from them about the deteriorating environmental and social conditions affecting poor, rural Kenyans — especially women. The women told her that they lacked firewood for cooking and heating, that clean water was scarce, and nutritious food was limited.

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Professor Maathai suggested to them that planting trees might be an answer. The trees would provide wood for cooking, fodder for livestock, and material for fencing; they would protect watersheds and stabilize the soil, improving agriculture. This was the beginning of the Green Belt Movement (GBM), which was formally established in 1977. GBM has since mobilized hundreds of thousands of women and men to plant more than 47 million trees, restoring degraded environments and improving the quality of life for people in poverty.

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As GBM’s work expanded, Professor Maathai realized that behind poverty and environmental destruction were deeper issues of disempowerment, bad governance, and a loss of the values that had enabled communities to sustain their land and livelihoods, and what was best in their cultures. The planting of trees became an entry point for a larger social, economic, and environmental agenda.

In the 1980s and 1990s the Green Belt Movement joined with other pro-democracy advocates to press for an end to the abuses of the dictatorial regime of then Kenyan president Daniel arap Moi.

Maathai went on to get elected as a member of parliament in Kenya in 2002, and to serve as deputy minister for the environment from 2003 to 2005. She continued working for sustainability, peace, and justice through the U.N. Environment Program and a number of other organizations.

Grist’s Amanda Little interviewed Maathai in 2005 and asked how she grew her organization to the point where it was it able to plant 30 million trees over its first 30 years. Maathai explained:

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On the very first day we planted seven trees, and I like to mention this because sometimes people get overwhelmed by 30 million. It is important to understand that this is a process, not something that happens in a bang.

Much more important than the trees themselves is the mobilization of rural populations in large numbers — populations that we normally think are helpless, are dependent, are not able to do things for themselves. They organized themselves and started to address the issues in their own communities to improve their quality of life. At its peak, we’ve had over 6,000 groups of women planting trees. In the process they educate themselves and address government issues. Eventually we became a pro-democracy movement.

Read more of Grist’s interview or the Green Belt Movement’s bio. You can also post condolences on Maathai’s Facebook page, and donate to GBM to honor her legacy and keep her work going strong.