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The Garden Scoop

Native Plants and Biodiversity

A startling report on global biodiversity was release by the United Nations this week noting an alarming trend in worldwide species extinction.  We, humans were pegged as the primary cause of an increase in extinction rates to the highest levels in human history.  Specifically, around 25% of the species assessed are threatened, suggesting that one million of the eight million known species of plants and animals are at risk of extinction.

Biodiversity refers to the variety of life on earth.  The great diversity of life on our planet maintains the life-support systems humans need for basic survival.  Think about the air we breathe, the water we drink, the soil that supports plant growth… all those basic elements of our environment are dependent on biodiversity— the diversity of species we have on earth.  As we lose biodiversity, our planet loses its ability to provide many of the things we all need to survive, as well as the spectrum of colors and sounds of life on Earth.

As a biologist and a gardener, this is a troublesome report to wrap my mind around.  Our footprint has grown large enough on a global scale to imperil on 1/8 of animal and plant life on this planet.  That alone is difficult to comprehend, but how does biodiversity relate to what I do as a gardener?

Simply put, the choice of plants we add to our gardens and landscapes can have an impact on biodiversity, with native plants providing the greatest benefit.  Our native plant life supports native insect populations, which in turn support larger animals creating a “food web” of interconnected species. 

Insects are an important transition point for energy within food webs.  Since many of them consume plant material, they consume the energy plants harness from the sun, and turn it into protein that larger animals need.  As insects consume, the vital energy our sun provides is transferred on to the animal kingdom and supports a diverse food web.

If native plants can begin to fill a larger proportion of our gardens, then all of our home landscapes can become valuable habitat to support native wildlife. Not only do we provide a home for our local flora but we support our fauna.

Earlier this week I had a conversation with Dr. Greg Spyreas, a plant biologist at the Illinois Natural History Survey.  Dr. Spyreas’ work focuses on conserving and restoring our native Midwestern flora and habitats.  In our conversation, I asked Dr. Spyreas to shed some light on the current status of Illinois native plant diversity.

“Worldwide, there are more than 250,000 species of vascular plants,” notes Spyreas. “In Illinois, we have greater than 2,500 species of native plants, over 300 of which are currently endangered.”

This means that over 300 plant species are at serious risk of being eliminated from the state or even going globally extinct in the very near term.

These numbers help to illustrate a point that Dr. Spyreas made, related to how preserving native plant diversity in Illinois fits into the global picture.

“Illinois’ 2,500 species of native plants represent about 1% of the global plant species numbers,” says Spyreas.

Although one percent sounds small, it’s actually a large number when you look at it from a global perspective.  We have an opportunity to preserve 1% of the plant biodiversity on this planet right here in Illinois and that’s and exciting number to me.

As gardeners, not only can we can do our part to preserve plant diversity by adding native plants to our landscape, we can help boost the diversity of native wildlife species due to the complex relationship between native flora and fauna.

Although the species of native plants suitable for gardening are not typically any of those that are endangered, many of which are far too sensitive to thrive in cultivation, there is a great number of natives that work wonderfully as landscape plants.  So, we might not be preserving the most at risk species, but we are certainly boosting native plant diversity at a very local scale, such as within your own yard or neighborhood.

One major challenge to planting more natives is sourcing the plant material.  The horticulture industry in general has not responded adequately to a growing demand for native plants.  The industry’s traditional plant selection relied on nonnative ornamental species.  However, as more and more gardeners begin to understand the great need to preserve plant diversity and support native wildlife, our purchasing choices can start to drive industry trends.  So, be sure to ask your local garden center where you can find the native plant section.  You may actually be pleasantly surprised at the result, with consumer demand eventually helping species conservation.

Special thanks to Dr. Spyreas for the great conversation and his contributions to the content of this week’s topic.