New Research on Biodiversity and Nature

A round-up of recent work published in scientific journals

Misguided reforestation in Africa. Starving polar bears. Amazon tipping point. Protected area trade-offs. Forest mercury emissions.

Misguided reforestation threatens tropical grasslands: Ecosystem restoration is booming, with tree-planting seen as a fast, effective approach. But according to this study, trees are being planted in many places where they do not belong — such as savannas and grasslands — in part because these habitats have been misclassified as forest. The authors analyzed plans by the African Forest Landscape Restoration Initiative to restore 100 million hectares of land by 2030, through planting and natural regeneration of trees. They found that nearly half of that area — the size of France — comprises non-forest ecosystems. And they add that almost 60 percent of tree-planting projects in Africa are using non-native species. They warn that inappropriate tree-planting could harm people and wildlife that depend on existing ecosystems. Similar issues are likely in other places, such as the savannas and grasslands of India and Brazil, they say. Read the press release or find the full paper in Science.

Polar bears stranded on land face starvation: Polar bears depend on the energy-rich fat of seals, which they best catch on ice. But as global heating extends the ice-free season in the Arctic, the bears are being stranded on land for longer periods. Some scientists have speculated that this could lead them to adapt — by resting for longer to save energy or by eating alternative foods such as berries or scavenged meat. But according to this study, polar bears that tried these approaches failed. The researchers tracked 20 of the animals over three summer weeks and found that nearly all lost weight rapidly. They expect an increase in starvation as polar bears are forced to spend more time on land, with adolescents and females with cubs most at risk. Read the press release or the full paper in Nature Communications.

Up to half of the Amazon rainforest at risk by 2050: The Amazon rainforest has been stable for millions of years. But deforestation, global heating and climate change threaten to trigger a self-reinforcing feedback loop that causes the loss of large areas of the forest, adding yet more carbon to the atmosphere and causing temperatures to rise further. This study estimates that by 2050 between 10 and 47 percent of the forest will be affected by drought and fires, potentially crossing a tipping point to an abrupt shift to savanna-like conditions, with major impacts on the regional and global climate. The authors say the Amazon’s future depends on ending deforestation, expanding restoration, and stopping global greenhouse gas emissions. Read the press release or the full paper in Nature.

Choosing between protected area expansion or enforcement: Most countries are now trying to expand their networks of protected areas to cover 30 percent of their territory by 2030. But as this study points out, with budgets limited, there is a trade-off between acquiring land to protect and better managing existing protected areas. Any expansion of protected areas will also mean that resources for managing and patrolling these areas are spread thinner. The researchers say that it is generally better to spend limited resources on improving enforcement in existing protected areas before establishing new ones. They demonstrate this with a case study of elephant poaching in Zambia, but say their findings apply across poacher-wildlife systems. Read the full paper in Biological Conservation.

Deforestation causes 10% of atmospheric mercury pollution: Mercury can cause major health problems if it enters water bodies and accumulates through the food chain. Trees mitigate this threat by absorbing mercury from the air — when leaves fall to the forest floor and rot, the soil absorbs the mercury. But when trees are cut down, this reduces the ability of forests to take up mercury and increases the release of mercury from soil. This study estimates that deforestation accounts for about 10 percent of all human-caused emissions of mercury to the atmosphere. In tropical regions, this increases greatly — to 40 percent in the case of Brazil. The authors warn that if deforestation of the Amazon continues at its current pace, mercury emissions have significant impacts on aquatic ecosystems. By contrast, conservation of the Amazon rainforest and global reforestation would both greatly mitigate mercury emissions. Read the press release or the full paper in Environmental Science and Technology.

See also, new papers on:

• Climate change and nature’s contributions to people in Madagascar

• Impacts of mega-fires of endangered Australian fruit bats

• A hundred key questions for seagrass conservation in Europe

• Ecological restoration or rewilding: What’s the difference?

• How large herbivores shape ecosystems around the world

• Critical vegetation types for biodiversity conservation in the Americas

In case you missed it…

Earlier this week I published Nature Beat #16 — full of news, resources, jobs, great stories, and more.

Nature Beat #16

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