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06-25-2024

Non-native species are spreading at an exponential rate

In a significant finding, an international team of scientists has discovered that non-native species are expanding their ranges at a rate 100 times faster than native species, largely due to inadvertent human assistance.

This rapid expansion is crucial as climate change accelerates, affecting habitats and necessitating swift adaptation by flora and fauna.

Speed matters in climate change adaptation

Plants and animals need to shift their ranges by 3.25 kilometers per year to keep pace with rising temperatures and climate shifts. Unfortunately, native species are struggling to meet this demand without human help.

By contrast, even seemingly sedentary non-native plants are moving three times faster than their native counterparts.

Human activity boosts non-native species

The research, led by a team from the University of Massachusetts Amherst, includes contributions from scientists in New Jersey, Michigan, Colorado, Hawaii, Sevilla, and Zaragoza.

The experts conducted an extensive review of previously published papers and datasets to determine how far and fast both native and non-native species are moving.

The study highlighted how human activities, whether accidental or intentional, are accelerating the spread of non-native species.

“We know that the numbers of invasive plant species are increasing exponentially worldwide,” said study lead author Professor Bethany Bradley.

Plant nurseries are exacerbating this spread, and confronting invasives is a critical step in preparing for climate change. We wanted to quantify the current movement rates of both native and non-native species.”

Human influence on species movement

The researchers determined that land-based species need to move at a rate of more than 3.25 kilometers per year to stay ahead of climate change, while marine species need to move at a rate of at least 2.75 kilometers per year.

According to the study, native species are only managing to move an average of 1.74 kilometers per year. Non-native species, on the other hand, are naturally spreading at a rate of about 35 kilometers per year.

With human intervention, the movement rate of alien species skyrockets to 1,883 kilometers per year – 1,000 times faster than native species.

“Essentially, there’s no chance for native species to keep up with climate change without human help,” spots Bradley.

Future implications for non-native species

The team also explored how far species might spread in a warming world. Although non-native species are likely to find more suitable habitats, they also risk losing territories as some regions become unsuitable.

“Non-native species might gain more territory with climate change, but they also have more to lose,” noted Bradley.

“We need to consider and implement assisted migration – deliberately helping native species move to more suitable locations – if our native plants and animals are to stand a chance.”

Proactive measures to support native species

The findings underscore the critical role that humans play in species distribution and highlight the need for proactive measures to support native species in the face of climate change.

Assisted migration could be a vital strategy in ensuring the survival of native flora and fauna as they struggle to keep pace with rapidly changing environments.

This comprehensive research offers a sobering reminder of the interconnectedness of human actions and ecological outcomes, urging immediate attention to invasive species management and climate adaptation strategies.

Examples of fast-spreading non-native species

Non-native species that spread rapidly can significantly impact ecosystems, economies, and human health.

One of the most notorious examples is the zebra mussel, native to Eurasia, which has spread throughout North American waterways, causing extensive ecological and economic damage by clogging water intake pipes and outcompeting native mussel species.

Another fast-spreading species is the cane toad, originally introduced to Australia to control pests but now proliferating uncontrollably, preying on native species and poisoning predators.

The Asian carp, introduced to the United States for aquaculture purposes, has spread throughout the Mississippi River Basin, outcompeting native fish for food and habitat.

The emerald ash borer, an insect native to Asia, has devastated ash tree populations in North America since its accidental introduction, leading to significant ecological and economic consequences.

The kudzu vine, native to Asia, was introduced to the southern United States for erosion control but has since spread aggressively, smothering native vegetation and altering ecosystems.

The study is published in the journal Annual Review of Ecology, Evolution, and Systematics.

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