Tijuca Forest & Refloresta Rio — Continuous Urban Reforestation to Protect Rio de Janeiro's Water Supply Since 1861

In the early 1800s, coffee-plantation clearing on the Tijuca massif above Rio de Janeiro stripped the hillsides and dried up the springs feeding the city's water supply. On 11 December 1861, an imperial ordinance ordered the systematic replanting of the Tijuca and Paineiras forests. Under administrators Manoel Gomes Archer (1862-1874, 1890-91) and later Gastao d'Escragnolle (1874-1888) and Auguste Glaziou (1889), more than 100,000 native trees were planted at a density of roughly 330 trees per hectare, 5.5 metres apart.

That planting was carried out substantially by enslaved and freed laborers. A 2024 Rio de Janeiro state law formally recognised 11 of them by name as heroes and heroines of the state -- Eleuterio, Constantino, Manoel, Mateus, Leopoldo, Maria, Sabino, Macario, Clemente, Antonio and Francisco -- and Brazil's federal prosecutors have since asked ICMBio, the park's manager, for historical-reparation measures including a memorial. No source found quantifies the true total labor force across the full multi-decade project.

The work continues today as Refloresta Rio (the Mutirao Reflorestamento program), run by the city's environment secretariat since November 1986. As of its 35th anniversary, the program had planted over 10 million seedlings of 273 native species (63 of them threatened) across more than 3,400 hectares in 92 of Rio's neighbourhoods, employing roughly 300 paid community workers drawn from the areas being reforested. It has been cited by the UN's Megacities Project and Brazil's Agenda 21 sustainable-development showcase.

The program's funding is municipal and has proven unstable: its workforce was cut from about 470 to 260 workers during a 2021 budget contingency before partially recovering. No modern hydrological study quantifying the forest's water-retention or erosion-control benefit was found, and the frequently cited claim of a 9C urban cooling effect traces to an unsourced tourism blog rather than a scientific study, so it is not used here.

Read the full analysis: https://oeco.org.br/reportagens/programa-de-reflorestamento-do-rio-faz-35-anos-com-desafio-ampliar-atuacao-e-recompor-equipe/