[[Invasive species]] are a big problem with prairies. Since fires cannot burn freely, many new species are taking over, and preventing sunlight from reaching shorter plants. In the United States, European [[buckthorn]] is a common problem. [[Garlic mustard]] is another. Often areas that once held a hundred different species of plants now only has three or four species. | [[Invasive species]] are a big problem with prairies. Since fires cannot burn freely, many new species are taking over, and preventing sunlight from reaching shorter plants. In the United States, European [[buckthorn]] is a common problem. [[Garlic mustard]] is another. Often areas that once held a hundred different species of plants now only has three or four species. |