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What makes an ecosystem vulnerable?

July 9th, 2024



Invasive species pose a major threat to Earth’s biodiversity, often disrupting natural ecosystems and outcompeting native species. Therefore, to mitigate the effects of these foreign visitors, it is important to know where they are most likely to appear and what management tactics are best suited to deal with them. The scientists in this study produced a model of vulnerability for environments, useful in identifying where more local efforts would be best used and where larger-scale change, like new policies or laws, are needed to prevent ecosystem destruction.

One of the major threats to biodiversity is the arrival of invasive or alien species [Vila et al., 2011]. These are species not native to an ecosystem, often displacing wildlife in the area. Therefore, a large portion of active conservation work focuses on removing these invasive species and preventing them from returning again in the future. The level of impact an invasive species has on an area is based on how suited they are to the environment they have invaded. For example, Japanese knotweed is tremendously well adapted to invasion due to its ability to grow quickly in various conditions and the fact that the numerous species in the group of plants can crossbreed, bringing a new mix of traits to suit new environments [2]. An ecosystem particularly prone to species invasion is the Florida Everglades, home to many tropic-adapted reptile and amphibian species, such as the corn snake, snapping turtle and the iconic American Alligator. However, records of invasive animals go back to the late 1800s, including cane toads, tokay geckos, chameleons, green iguanas and the infamous Burmese python. The latter species is one of the most famous invasives, known for eating many of the Everglades’ native wildlife, creating a prolonged ecological problem in the area, with efforts to cull and remove the species being carried out over decades [3].

To address some of these issues, a team of scientists worked to identify what makes an environment vulnerable to invasion by plant species in the United States. The study aims to provide a framework for plant surveys across various habitat sizes, ranging from small local areas to whole ecosystems and state-wide landscapes. The study used existing data collected by a national ecological network to calculate native species richness and the level of invasions in different areas across the country. Species richness was assessed using net primary production, which is the amount of plant growth that provides food for animals, as it can be assumed that areas with more plant growth would have more resources, leading to a greater number of different species. Other environmental factors, such as temperature and rainfall, were also considered to see how these conditions affect both the variety of native species and the presence of invasive species.

The results uncovered the unsettling reality that non-native plant species exist in almost 70% of the area surveyed. They found that local, small-scale sites were more vulnerable in colder regions than in warmer climates but that this scale was reversed when looking at larger areas, where warmer regions were far more vulnerable. At a local level, it is theorised that colder sites may be more vulnerable because many invasive species send out their flowers and leaves earlier than the native plants, which have adapted to the short growing season, giving the invasives a competitive advantage. Computer models based on the data collected also confirmed that invasive species reduce the number of native species in all types of environments.

In summary, invasive species pose a significant threat to biodiversity, disrupting ecosystems and outcompeting native species. This study provides a valuable model for understanding the vulnerability of different environments to invasion, highlighting the need for targeted local efforts and broader policy changes. By identifying areas at risk and understanding the factors that facilitate invasions, we can better strategize conservation efforts to protect native ecosystems.

How to Find Another Way

These findings highlight the importance of increased conservation efforts to combat invasive species and protect our ecosystems. Although that sounds very gloomy, there are things we can all do to help protect our local ecosystem. For example, we can choose to plant native species in our gardens instead of foreign alternatives, such as the British bluebell over its European cousin. Or we can report sightings of invasive species to authorities and participate in community weed-picking programs to help manage the spread of foreign species. Additionally, thoroughly cleaning recreational gear such as walking trousers and shoes and staying on designated paths can help prevent the unintentional spread of invasive species, especially when travelling to new environments.

Article by Fin Mills

References:

Article Paper: Ibáñez I, Petri L, Barnett DT, Beaury EM, Blumenthal DM, Corbin JD, Diez J, Dukes JS, Early R, Pearse IS, Sorte CJ. Combining local, landscape, and regional geographies to assess plant community vulnerability to invasion impact. Ecological Applications. 2023 Jun;33(4):e2821.

[1] Vilà M, Espinar JL, Hejda M, Hulme PE, Jarošík V, Maron JL, Pergl J, Schaffner U, Sun Y, Pyšek P. Ecological impacts of invasive alien plants: a meta‐analysis of their effects on species, communities and ecosystems. Ecology letters. 2011 Jul;14(7):702-8.

[2] Richards CL, Walls RL, Bailey JP, Parameswaran R, George T, Pigliucci M. Plasticity in salt tolerance traits allows for invasion of novel habitat by Japanese knotweed sl (Fallopia japonica and F.× bohemica, Polygonaceae). American Journal of Botany. 2008 Aug;95(8):931-42.

[3] Engeman R, Jacobson E, Avery ML, Meshaka Jr WE. The aggressive invasion of exotic reptiles in Florida with a focus on prominent species: A review. Current zoology. 2011 Oct 1;57(5):599-612.

Photos: Angus MacAskill/Flickr, Andy Wraithmell/Flickr, Leela Channer