22 January 2024

The impact of agricultural deforestation on biodiversity is not the same everywhere

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Some features promote the resilience of certain species to the effects of deforestation, a Peking University study has found. But biodiversity conservation is also affected by local agricultural history

by Matteo Cavallito

 

Deforestation for agricultural purposes poses a threat to biodiversity conservation. But the impact of logging on the survival of different species varies widely among different regions of the world. This is claimed by a recent Peking University study involving 49 different institutions across the Planet that focused on bird communities.

“Regions differ inherently and predictably in how sensitive their bird communities are to agricultural deforestation,” explains a statement from the Chinese university. The survey was recently published in the journal Nature Ecology & Evolution.

An “historical” selection

“What we found is that natural environmental conditions and past human influences have essentially served as filters to determine what kinds of species—in terms of tolerance to agricultural deforestation—are present in a region’s bird community today,” explained Fangyuan Hua, a Peking University professor and co-author of the study. Not unlike other human-caused events in the past, in short, species that have been more adapted over time to cope with changes in their habitat would now be more tolerant of agricultural deforestation.

A case in point are the bird communities of East Asia, which, the researchers recall, are located in an area characterized by millennia of prior agricultural history. Added to this is the so-called “second filter,” represented by environmental characteristics. Species that live in more variable environments, the researchers go on to explain, are predisposed to a wider range of conditions and should have adapted better to them.

An investigation of deforestation

“Previous efforts to explain this variation have focused exclusively on the landscape features and management regimes of agricultural systems, neglecting the potentially critical role of ecological filtering in shaping deforestation tolerance of extant species assemblages at large geographical scales via selection for functional traits,” the study notes. In collaboration with other global-scale research centers, the authors thus developed a database of 71 regional communities and 2,647 bird species.

This enabled them to test whether environmental conditions and agricultural history could explain global variation in the impact of deforestation on biodiversity.

In summary, bird species tend to be filtered based on functional traits that influence adaptation to deforestation. More tolerant species, for example, tended to be smaller and more migratory, less dependent on mature natural forests and less demanding of food resources. These features were also more common in birds found in regions with more variable natural environments and longer agricultural history.

Impact of forest destruction is greatest in the tropics

Species loss is now considered a real emergency that ranks alongside climate change in importance. In this context, the study points out “that biodiversity in some regions is more inherently threatened by agricultural deforestation than in others.” Prominent among these are tropical areas that have less agricultural tradition and less variable environmental conditions.

In these areas of the Planet, the authors point out, it becomes especially necessary to plan agricultural land use to reduce deforestation.

But the message, of course, applies generally to all forests. “Our results also underscore the importance of conserving existing intact forests, the Earth’s rapidly disappearing strongholds of complete species assemblages,” explains Paul Elsen, a researcher at the Wildlife Conservation Society in New York and co-author of the study. “Otherwise, the inevitable filtering and loss of sensitive species will only further erode the diversity of Earth’s life forms.”