Diversity: Roots in All Depths

Some Plants Have Deep Roots

Years ago I saw a picture of a man standing next to the unearthed root system of an Indiangrass; the root system must have been twice as tall as the man!  “Wow,” I thought, “It is no wonder that this grass species does so well in a drought.”  It can get water that is from 15 feet down in the soil.  With that impressive picture in my mind, I continued to think about the advantages this plant has.  Not only does it have access to all of that water, but it can get nutrients from that deep as well.  Interestingly, some plant essential nutrients are either more abundant or more available to the plant in lower horizons (or levels) of the soil.  Deep rooted plants often are very steady in their production.  Come what may – be it drought or inches and inches of rainfall – these plants will just keep growing at a steady rate.  It is a draft horse.  Day in, day out, the horse goes to work in the field.  He never wins any races for speed, but he can always be found out there getting the job done.  Steady and reliable…it could be the motto of the draft horse and the deep rooted natives.

Some Plants Have Shallow Roots

As I contemplated this, it occurred to me that if all of the plants in the field have deep root systems, then the next door neighbor also has a deep root system and is a direct competitor.  It would be better to have root systems of neighboring plants that are different so they can collect water and nutrients from different areas of the soil.  Shallow rooted plants have their place.  In fact, shallow rooted species tend to be more like racehorses.  They respond to moisture rapidly and convert it to growth.  However, after the race or when the drought comes, they shut down and quit.  They react in a similar fashion to fertility.  Whether the fertility comes in the form of dung and urine from wildlife and livestock, the ashes of a fire, nutrients that are recycled from dead plant material or a fertilizer truck the shallow-rooted plants quickly take advantage of these newly found nutrients.  The motto of the racehorse and the shallow rooted plants is that when conditions are good, go fast and furious, but otherwise stand and watch the world go by.  Many native cool season plants have shallow root systems and consequently respond quickly to the usually abundant rainfall in spring and fall.  

What Does a Variety of Roots Mean for the Ecosystem?

In all of the time in the last 30 years that we have spent time on the native grasslands, we have observed that there are dramatic ebbs and flows in the production of everything from leaves to blooms and seeds depending upon the type of root system.  From the perspective of folks interested in using native plants for forage, diversity means that the available water and nutrients are most efficiently used to produce the most forage possible.  From a wildlife viewpoint the diversity of root systems means that regardless of the soil water and nutrient conditions, there will be blooms for nectar, seeds for food, plant leaves and other parts for consumption by not only wildlife but also insects that many species of wildlife eat; sometimes the deep rooted plants will be the major producers and at other times the shallow rooted plants will take advantage of the situation to produce the food and habitat.  Landscapers can find that a mix of deep and shallow rooted plants will be more likely to provide blooms year in and year out.  And, lastly, the folks interested in restoration find that the diversity of root systems is in the design of our native grasslands, and it is a great blueprint to replicate. 

Native grasslands have an amazing diversity of root systems:  deep vs. shallow, fibrous and spreading vs. tap rooted and penetrating.  This diversity lends resiliency to the native grasslands; they can withstand and even thrive following a variety of disturbances.  Diversity is as good as it gets!