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Friday, March 1, 2024

Habitat fragmentation threat to biodiversity, research shows

Low human impact areas too isolated, may be detrimental to environment

Half the Earth must be set aside for nature in order to prevent a mass extinction and preserve biodiversity, according to biologist and pulitzer winner Edward O. Wilson. With about 200 species going extinct every day, many argue that a serious conversation about the conservation of biodiversity is dramatically in need. There is still the opportunity to protect such vast areas of the planet, according to a recent study by the National Geographic Society and co-authored by UC Davis conservationist researcher Jason Riggio. 

The study — which was released in early October as a global inventory — revealed that 56% of the planet, not including permanent ice and snow, is in low impact areas (LIA) distributed non-randomly across all continents and biomes. The areas were revealed to be severely fragmented, in the sense that there is little contact between multiple LIAs, reducing the opportunities for species in these areas to intermingle. While the discovery of vast amounts of relatively untouched wilderness provides hope to those who focus on conservation, it is this isolation of these LIA fragments that appears to be the real threat to biodiversity. 

This study also proclaims that there is still an opportunity to protect the areas of the earth will little to no human impact for the benefit of humans and the overall environment. Lead author of the study Andrew Jacobson, a geographic information systems professor at Catawba College in North Carolina, considers these results “conservative” though. 

“There are likely more patches that are smaller and with more edge […] than what we show,” Jacobson said. “Because we were doing a global analysis, we couldn’t afford to have a miniscule grain [plot of land] size, and so inevitably we are missing some of these fragmentation patches at a really fine-grained scale.”

The areas identified were not evenly distributed across biomes, however. Tropical dry forests and temperate grasslands were discovered to be extensively converted, with high levels of human impact. Ninety percent of tundra and boreal forests, on the flip side, were LIAs, making them the least converted. It is essential to acknowledge this disparity, according to Riggio. 

“There is this story that half the planet is low human impact,” Riggio said. “But most of what remains, almost three-fourths, is in high, cold and dry places.” 

Riggio thinks it is important to highlight that “[a]reas with the most biodiversity and the most threatened species do not have half their land” when the discussion on efforts toward conservation take place 

“The distribution of these places is biased towards inhospitable land,” Riggio said.

LIAs, in this context, do not mean areas completely devoid of human presence. Indigenous lands and lands with few people and livestock were designated as LIAs for this study.

“By our process, we did not necessarily exclude areas that had people. We did not set any type of base, any type of threshold, say, if we know there is one person in this landscape then it’s no longer a low impact area,” Jacobson said. “As long as the lands weren’t converted to some urban area — or there weren’t extensive croplands […]  — and have relatively low densities of people, it was still a low impact area, so a lot of these indigenous lands were probably captured within those low impact areas.”

National Geographic became interested in this subject in an attempt to find what was initially referred to as “the last wildplaces,” according to Riggio. What it evolved into was this study of how much land remains in a natural state to help set a target for the Convention of Biological Diversity (CBD) 2020. 

The CBD is a United Nations sanctioned international legally-binding treaty. 

“It is an internationally agreed plan to save biodiversity for future generation using specific targets as to the extent of terrestrial and marine areas to be protected,” said Tim Caro, a conservation biologist and behavior and evolutionary ecologist, via email.

Currently, only 15% of the Earth’s land is protected, although the push to dramatically raise protected area targets to 50% exists. 

“Our goal was accessing what percentage of the planet had a low human impact within the context of the Convention of Biological Diversity 2020 to set an ambitious target for land conservation,” Riggio said.

The intentions of the study were to see what remains and how those ambitious conservation targets could be achieved. 

This issue is not as distant or removed as it may seem. The Berryessa Snow Mountain National Monument, for instance, is an example of a LIA. Caro said the study is “an academic wake-up call to the devastating impact of humans on natural places.” 

Habitat fragmentation and its effects had received little attention prior to this study, and it shows that while much damage has been done, there is still a chance for preservation. Already, governments globally are taking steps to ease the burden of fragmentation on wild populations. 

Building wildlife corridors, which Riggio and Caro have studied, and linking habitat patches are steps toward maintaining the genetic variability of threatened species and alleviating the threats fragmentation creates. California’s own wildlife overpass is a testament to the genuine effort being put into solving habitat fragmentation. 

Written by: Husn Kharabanda — science@theaggie.org


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