The world has become a smaller place due to the ease of getting from one side of the globe to the other via jet airplanes. This is great for people who need to get somewhere quickly, and it enables perishable foodstuffs to reach their destinations before they go bad. But the increase in speedy global travel has also helped to increase the spread of plant species that sometimes threaten native plants by dominating their environments.
What is an Invasive Species?
Invasive species occur in habitats around the world. They are sometimes introduced purposely because people believe they will provide a benefit to their new home, such as a fast-growing source of lumber or simply as an attractive landscape ornamental.
When a plant escapes cultivation in a conducive area where it has been introduced, it can shade native plants growing in the same environment and it can drop its seeds or reproduce through runners or other means. It can literally take over an environment and often causes native plants to cease having the conditions they need to flourish.
Weeds Can Be Trees or Small Plants
Many trees have become "weeds" in areas where they have been introduced. For example, in Tahiti and Hawaii the invasive Miconia tree has taken over thousands of acres of forested areas and has disabled many native species from living in its environment. Other tropical invasive trees include the albizia, schefflera, trumpet tree (Cecropia), autograph tree (Clusia), strawberry and yellow guava and many others.
How Weedy Species Spread
Scientists use several criteria for classifying plants as invasive. These include their rapid growth, early maturity, large seed-producing capability, short amount of time required for seeds to germinate and also effective methods of dispersing their seeds. Successful invasive plants effectively use local pollinators such as bees, moths and other insects. They typically produce a dense canopy of shade, which makes them out compete native plants.
These plants are capable of reproducing in several different ways, including vegetative growth from their root systems and the ability of branches that break off to sprout roots and form new plants.
Why We Need Native Plants
Biodiversity is an important aspect of ecosystems. The plants that have evolved in a particular area provide food for humans, insects and animals. They play a vital role in the balance of nature by providing habitats for native animals and they define the characteristics of an environment. For example, in areas that once contained large forests of native trees that vanished due to logging, desert-like environments have resulted that cannot support the native animals and other plants that once lived there.
What You Can Do
Wherever you live, if you have a garden you can help to conserve your local native plants in several ways. Before you purchase seeds or plants for your yard do a little research to learn about them. All states and many countries have a Native Plant Society that you can contact to learn about the plants that are native to your area and also the invasive plants you should avoid growing in your yard.
Also, make an attempt to grow at least a few plants that are native to your region---they will serve you well because typically they are very hardy perennials that require little water, fertilizer or other care.