by Jane Marsh

Plants have existed for millions of years and have evolved to survive many harsh conditions. But today, many plants face decimation and extinction threats from their own kind — the alien plants. Posing various harm to native habitats and human livelihoods, these plants are becoming increasingly dangerous to the ecosystem.

What are Alien Plants?

Alien plants are those that are non-native to an ecosystem. These plants, sometimes also called exotic plants, are usually intentionally or accidentally introduced by man. In some instances, these plants provide benefits to the ecosystem. However, in many cases, their invasiveness can cause environmental issues in the surroundings.

However, not all invasive plants are native, and vice versa. It is also important to note that not all exotic plants introduced into a non-native habitat successfully invade the ecosystem. Some coexist with the native flora, and some may die due to their inability to survive in the new ecosystem.

How Does Invasion Occur?

For a non-native species to take hold in a foreign land, it has to be introduced by man. For example, a tourist bringing back an exotic plant to their homes or seeds stuck to car tires while on a wilderness trip. In some cases, migratory birds have contributed to the distribution.

Urban gardening has also contributed to the irresponsible practice of introducing alien plants to other habitats. In the U.S., invasive plants have reduced 42% of endangered and threatened species, and invasion is the main cause of 18% of these species. 

Many people compete to have the most aesthetically pleasing, ‘Insta-worthy’ yard or indoor ornamental garden in their homes, forgetting the harm these non-native species could pose to the local flora and fauna. 

In addition, some people’s beliefs that specific plants bring luck, wealth, or health add to this practice. They tend to incorporate non-native flora into their homes, causing native plants to compete for resources and struggle to survive. 

Beyond this, invasion occurs when these plants are introduced into a land with native flora and fauna. There are many ways this could happen naturally. Among them are:

• Ability to grow long roots: Some plants can grow lengthy and dense roots to reach far for resources, smothering other plants surrounding them.
• Can produce a large number of seeds: Many alien plants have evolved to make a lot of seeds to ensure survival.
• Seeds distributed by agents: Humans, animals, and wind work as distributors of these seeds. A classic example is bees pollinating flowers. Humans unintentionally distribute through their clothes, shoes, and other mediums. In an urban setting, vehicles also play an essential part in distribution.
• Chemical defense system: Some alien plants invade by releasing chemicals that could cause diseases or kill other nearby plants. These sick plants often exhibit issues like thinning, lesser leaf volume, and peeling in the bark, trunk, and other parts. 

What are the Impacts of Alien Plants?

The worldwide economic cost of invasive alien species, including flora and fauna, was more than $423 billion in 2019 and has increased at least four times every decade since 1970. Only 6% of plants are known to be invasive — even these are causing significant impact on the survival of native plants.

Here are some of the aspects that these alien plants disrupt in a new habitat:

• Soil: Introducing some alien plants changes the soil chemistry, making it unsuitable for plantation and agriculture. 
• Native plants: These invasive plants can usurp the resources of existing plants in a habitat, including vegetables, herbs, plants, and trees, causing the native plants to go extinct. 
• Animals: When the native plants are gone, animals that rely on them for food are forced to relocate. Some alien plants are also poisonous to animals, killing them when ingested. 
• Crop yield: Alien plants can outcompete crops like rice and wheat. In addition, these plants disrupt irrigation, causing issues in fisheries. An example is the invasive water hyacinth. It can populate drastically in 12 days, causing blockage, slowing boats, and causing problems with finishing and trade. 
• Human: Alien invasive plants threaten food cultivation and the livelihoods of about 1.23 billion people worldwide, indirectly contributing to food insecurity, poverty, and malnutrition in many parts of the world.
• Climate: Invasive plants can contribute to vulnerability in the ecosystem, causing a more prominent climate change impact. 

What can be Done?

Scientists are recommending actions to curb the ecological harm caused by alien plants. In response, many plants have been banned in areas to allow native plants to grow and prosper. For example, the Asian native Callery pear tree is banned from sale in Pennsylvania.

This sparks a conversation on how authorities can work to eradicate invasive plant issues and improve natural ecosystems. Climate change efforts should include the control of invasive plants, and more native plants should be used for environmental strategies like erosion control and carbon optimization. 

Alien Plant Invasiveness Control is Needed for A Healthier Ecosystem

Alien plants must be monitored to ensure a controlled and better ecosystem. Risk mitigation is paramount, so stakeholders should come together to act promptly and efficiently. 

Article by Jane Marsh

Jane works as an environmental and energy writer. She is also the founder and editor-in-chief of Environment.co