Increasingly, nonnative plants and animals are invading places we love, like forests, wetlands, and even our yards. These nonnative or exotic invaders can change many big picture ecosystem processes that we rarely think about. Ecosystem processes are important aspects of how ecosystems work. An example of these processes is the cycling nutrients like nitrogen or phosphorus. These nutrients flow from the soil to plants, then to animals and then back to the soil. The composition of plants in a forest influence how quickly these processes work, which in turn influences how the community of plants and animals change and evolve through time.
Changes in plant communities that accompany exotic plant invasions can ripple through ecosystems, altering animal habitat and affecting nearby streams and wetlands. Chinese privet (Ligustrum sinense) is a very common invasive exotic plant that invades many forests and wetlands. Research on the effect of privet in forests shows that as the amount of privet in forests increases, the speed of forest floor decomposition also increases. This means that as the leaves fall to the forest floor, the leaves are more rapidly eaten by bacteria, worms, insects and other critters in the soil. Ultimately, this means the nutrients from the leaves are more rapidly released back into the soil, and are able to be taken back up by plant roots.
Privet leaves are generally higher in nitrogen than are native species and nitrogen is an important nutrient. Privet takes up nitrogen and other nutrients very quickly, grows very fast, and produces lots of berries and seeds. Also, privet leaves are low in strong carbon compounds like cellulose and lignin, contributing to a quicker breakdown. Collectively, this means that as privet invades a forest (or yard), ecosystem processes like nutrient cycling speed up, enabling privet to rapidly expand and dominate over other species. This is not good for native wild flowers, birds, insects, and other species that live in our treasured forests and yards.
But there is still hope for these places we love. Large areas are being managed for the removal of privet, usually with volunteers from local citizen groups. Groups like Weed Warriors of Athens, Georgia and Western North Carolina Alliance (WNCA) are actively removing privet in forests, along roadways and in city parks. You can help protect parks and forests buy removing plants like privet from your yard and replacing them with native plants. The southeast has many beautiful native plants such as American Holly (Ilex opaca) and Cinnamon Clethra (Clethra acuminata) that are great additions to your and benefit wildlife. Think about letting your local nursery or plant retailer know that you support native plants over invasive exotic alternatives, and that the protection of native forests (and your yard) is an issue that is important to you.
J.D. Mitchel, G. Lockaby and E. F. Brantly. 2011. Influence of Chinese Privet (Ligustrum sinense) on Decomposition and Nutrient Availability in Riparian Forests. Invasive Plant Science and Management. 4:437-447.
J. Wilcox and C. W. Banks. 2007. The effects of Ligustrum sinense Lour. (Chinese Privet) on Abundance and Diversity of Songbirds and Native Plants in a Southeastern Nature Preserve. 6:535-550.