New study helps unravel the paradox of habitat fragmentation on biodiversity
Around the world, roads contribute to habitat fragmentation. (Picture: A. J. T. Johnsingh, WWF-India and NCF, CC BY-SA 4.0, via Wikimedia Commons)
New insights could impact future conservation strategies.
Based on a media release by Professor Dr Jinbao Liao, Yunnan University
Habitat fragmentation, a process where a large, continuous habitat is divided into smaller, isolated areas, can both help and harm biodiversity, depending on the total amount of habitat remaining in the landscape, according to a new study published in Nature Ecology & Evolution.
The research by Professor Jonathan Chase of the German Centre for Integrative Biodiversity Research (iDiv) and the Martin Luther University Halle-Wittenberg (MLU) and his collaborators shows that the total amount of habitat remaining in a landscape can moderate whether more or less fragmentation in the remaining habitats can increase or decrease diversity.
Many studies show that habitat destruction, often due to human activities, is the predominant cause of biodiversity loss and change. However, there has been a lot of discussion about the role of habitat fragmentation, which can be caused by the construction of roads and urban development, for example.
“There has been a lot of contention about just how ‘bad’ fragmentation really is for biodiversity,” Chase explains. “While it is clearly bad for some species, other species are quite happy.”
Among ecologists and conservationists, this debate is known as the SLOSS (Single-Large-Or-Several-Small) debate and centres around the question of whether one large reserve can maintain more species than several small reserves.
Better a dandelion in the wind?
The results show that when habitats are largely intact, small amounts of fragmentation can favour species that take advantage of habitat isolation. These species are good colonisers, like the common Dandelion (Taraxacum officinale), whose seeds fly on the wind and find any open space to grow. This allows them to coexist among more competitively dominant species, leading to overall higher diversity and positive fragmentation effects.
However, when large amounts of habitat have been destroyed, fragmentation can lead to negative effects on biodiversity by causing the most competitive species to go extinct. These species are the poorest colonisers, like bunchgrasses, which grow in clumps and are long-lived with strong root systems.
Although the model used by the researchers is simplified, its general characteristics are likely applicable in many natural metacommunities. To illustrate this, the researchers show that the general predictions of this framework — shifts from positive to negative fragmentation effects with increasing habitat loss — are consistent with data from a compilation of fragmented metacommunities across the globe.
“Our study provides theoretical grounds to reconcile this binary perspective and also points a way towards designing landscapes that minimise biodiversity losses,” Chase adds.
Original publication
(Researchers with iDiv affiliation are bolded)
Zhang, H., Chase, J.M. & Liao, J. (2024). Habitat amount modulates biodiversity responses to fragmentation. Nature Ecology & Evolution, DOI: 10.1038/s41559-024-02445-1
Contact:
Prof Dr Jonathan Chase
Head of the Biodiversity Synthesis research group
German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig
Martin Luther University Halle-Wittenberg
Phone: +49 341 9733120
Email: jonathan.chase@idiv.de
Web: www.idiv.de/en/groups-and-people/core-groups/synthesis.html
Christine Coester
Media and Communications
German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig
Email: christine.coester@idiv.de
