Why does it benefit when we cut down the foreign plants and plant back the native plants?

For example, there is a lot of Buckthorn in the Midwest states where Buckthorn is originated in Europe. Why do we need to cut down the foreign plants and plant back the native plants like Hawthorn to the Midwest climate. What is the benefit and advantage?

Why does it benefit when we cut down the foreign plants and plant back the native plants?
Sometimes non-native plants take over the landscape. They will grow so strongly and wildly that the native plants, that naturally do well, will be killed off. The key word is naturally. For example, coneflower in Wisconsin is a native plant. They have proven themselves to grow best here and are considered native because they HAVE survived so many years here. If a plant comes along that can temporarily do well here, takes over and kills off the coneflower (and other natives), but then during a really hot summer or way below zero winter dies off, there would be nothing left eventually.
Reply:There are several reasons that this is a benefit, but, arguably, the main one is that often the native animals are "used to" the native plant. In other words, they are usually "better off" with the native plants. So, if you preserve the native plants, you will preserve the native animals better.