Invasive plants

Invasive species – including plants, animals and fish – cause heavy damage to crops, wildlife and human health worldwide. Some prey on native species; other out-compete them for space and food or spread disease. A new United Nations report estimates the losses generated by invasives at more than US$423 billion yearly and shows that these damages have at least quadrupled in every decade since 1970. Humans regularly move animals, plants and other living species from their home areas to new locations, either accidentally or on purpose. For example, they may import plants from faraway locations to raise as crops or bring in a nonnative animal to prey on a local pest. Other invasives hitch rides in cargo or ships’ ballast water. When a species that is not native to a particular area becomes established there, reproducing quickly and causing harm, it has become invasive. These recent articles from The Conversation describe how several invasive species are causing eco...

Spring is planting time for home gardeners, landscapers and public works agencies across the U.S. And there’s rising demand for native plants – species that are genetically adapted to the specific regions where they are used. Native plants have evolved with local climates and soil conditions. As a result, they generally require less maintenance, such as watering and fertilizing, after they become established, and they are hardier than non-native species. Many federal, state and city agencies rank native plants as a first choice for restoring areas that have been disturbed by natural disasters or human activities like mining and development. Repairing damaged landscapes is a critical strategy for slowing climate change and species loss. But there’s one big problem: There aren’t enough native seeds. This issue is so serious that it was the subject of a recent report from the National Academies of Sciences, Engineering and Medicine. The study found an u...

With spring settling in across the U.S. and days lengthening, many people are ready to spend more time outside. But after a walk outdoors, have you ever found seeds clinging to your clothes? Lodged in your socks and shoelaces? Perhaps tangled in your pet’s fur? While most of us don’t give these hitchhikers much thought, seeds and burrs may be the first signs of invasive plant spread. Certain species of non-native invasive plants produce seeds designed to attach to unsuspecting animals or people. Once affixed, these sticky seeds can be carried long distances before they fall off in new environments. With favorable conditions, they can become established quickly and outcompete native plants. Outdoor recreation has expanded at a record pace across the U.S. in recent years. Overcrowding in outdoor spaces has many harmful effects, from degrading trails to accelerating the introduction and spread of invasive plants. As a recreation ecologist and an avid hiker, I study h...

When people think of spring, they often picture flowers and trees blooming. And if you live in the U.S. Northeast, Midwest or South, you have probably seen a medium-sized tree with long branches, covered with small white blooms – the Callery pear (Pyrus calleryana). For decades, Callery pear – which comes in many varieties, including “Bradford” pear, “Aristocrat” and “Cleveland Select” – was among the most popular trees in the U.S. for ornamental plantings. Today, however, it’s widely recognized as an invasive species. Land managers and plant ecologists like me are working to eradicate it to preserve biodiversity in natural habitats. As of 2023, it is illegal to sell, plant or grow Callery pear in Ohio and Pennsylvania, and will become illegal in South Carolina on October 1, 2024. North Carolina and Missouri will give residents free native trees if they cut down Callery pear trees on their property. How did this tre...