Protection mosaic promotes high biodiversity

A new study has found a mix of different ecosystem management strategies promotes high regional species biodiversity—but favours very distinct species communities of plants, birds and fish.

The international team, including Coral CoE researchers, found that the number of species remains unchanged between protected and non-protected areas within the same region. Their work also questions the use of species diversity (number of species) as the sole indicator of the ‘good’ ecological status of an ecosystem or as a management target.

The key role of protected areas in conservation is unanimously recognised: certain species vulnerable to human pressures are much more present and abundant within their boundaries than outside.

However, until now, the benefit of protected areas for species diversity remained mostly unexplored. As did the extent to which adjacent areas with distinct protection levels—Strictly Protected, Restricted, and Non-Protected—host different species numbers and compositions.

The researchers looked at the difference in species diversity between protected and non-protected areas in the same region when habitat, environment, sampling effort and rarity are controlled.

To answer this question, they analysed data of Indo-Pacific coral reef fishes, French alpine plants and North American birds. This is more than 5,500 species observed in 655 protected areas and adjacent restricted and non-protected sites.

The results of the study show distinct groups of species are present in strictly protected areas compared to restricted areas and adjacent non-protected areas. For example, 12–15 percent of species were found exclusively in non-protected areas. This indicates many can tolerate and even thrive in habitats disturbed by human activities.

However, for IUCN Red Listed species, 58 percent of fish, 11 percent of birds and 7 percent of plants were confined to areas with the strictest protection measures. This further highlights the fundamental and unique role of protected areas—and their environmental conditions—in conservation. The result also suggests humans, through their activities, shape very different species assemblages. There is a clear difference in the species dependent on anthropised ecosystems from those dependent on protection measures to persist.

The authors conclude: “We suggest that, in a world with a predominance of altered landscapes and seascapes, reinforcing Strictly Protected areas with Restricted areas nearby may create a mosaic of protection levels maximising the number of species at the regional scale, an important outcome for sustaining ecosystems and their services.”

“Broadening and diversifying the scope of conservation options to not only focus on local versus global issues but also include regional contexts is critical to prevent future extinctions and to maintain ecosystem multifunctionality under fluctuating and uncertain environmental and human stressors.”

PAPER

Loiseau N, Thuiller W, Stuart-Smith R, Devictor V, Edgar G, Velez L, Cinner J, Graham N, Renaud J, Hoey A, Manel S, Mouillot D. (2021). ‘Maximizing regional biodiversity requires a mosaic of protection levels’. PLoS Biology. DOI: 10.1371/journal.pbio.3001195