On the hilly slopes surrounding Antananarivo, where modern neighborhoods coexist with rice paddies, an unexpected story unfolds: ancient sacred hills, known as ‘doany’, are home to dozens of native tree and shrub species—plants that are rare in ordinary city parks and vacant lots. These places hold the silent memory of the pre-colonial period when the central highlands of Madagascar were covered in forest.
A study published in Nature Cities surveyed 329 natural plant regeneration sites in the agglomeration of Madagascar's capital. Scientists analyzed over 25,000 young woody individuals of 206 species, discovering that 39 percent of them were native species. A critical pattern became evident: the richness of native flora significantly declines with increased development density and higher socioeconomic levels in a district. Exotic invasive species, conversely, thrived regardless of these factors.
Notably, seven of the ten most biodiverse sites are located on sacred hills—places where ancient traditions have prohibited economic activity. These hills are linked to the memory of the Merina royal dynasty, and many of them bear traces of the pre-colonial era. To this day, local people rarely cut trees or develop these areas, observing ancient traditions of respect for their ancestors. Near the sacred hills lie primary forests, protected for centuries thanks to ‘fady’ taboos—cultural prohibitions rooted in Malagasy culture. These taboos forbid the felling of trees, excavation, and burials in sacred forests where the remains of royal ancestors rest.
Urbanization alters many filters through which seeds pass: the landscape between sites transforms, construction pressure intensifies, and traditional prohibitions erode. In city parks and vacant lots, hardy, often introduced species dominate, well-adapted to disturbed soils and pollution. On the sacred hills, the cultural prohibition acts as an invisible shield, allowing native plants to sprout, take root, and reproduce without direct human intervention.
The findings suggest that in growing tropical cities, socio-cultural factors can be as significant as ecological variables. For Madagascar, where 93 percent of tree species are endemic and urbanization is proceeding rapidly, this pattern is critical. Where formal conservation statuses have not yet been established, ancient traditions of nature reverence continue to serve as unofficial nature reserves—a form of biodiversity insurance in situations where state measures often lag behind.
Sacred sites cannot and should not replace full-fledged national parks and reserves—but they demonstrate a unique pathway: respect for cultural heritage and local traditions can simultaneously serve the cause of nature conservation. In urban landscapes where formal protection lags behind development rates, these 'invisible' refuges become an important element in the biodiversity mosaic, a link between the past and the future.
The conservation and respectful treatment of sacred sites represent one of the most accessible and culturally sensitive ways to support native plant diversity in rapidly growing Afrotropical cities, where traditional wisdom intertwines with ecological necessity.
