Planting to Combat Global Warming

September 2024 by Christa Orum-Keller

NASA defines global warming as the long-term heating of Earth’s surface observed since the pre-industrial period (between 1850 and 1900) and credits human activities as the cause. These activities increase heat-trapping greenhouse gas levels in the Earth’s atmosphere.

The data from NASA tells us that human activities have increased Earth’s global average temperature by about 1 degree Celsius (1.8 degrees Fahrenheit) and the temperature is anticipated to continue increasing by .2 degrees Celsius per decade.  See the illustration below.

What warms the planet is the increase of greenhouse gases, including CO2, methane, nitrous oxide, and chlorofluorocarbons (CFCs). CO2 accounts for more than half of the total greenhouse gases.

Carbon sequestration is the process of capturing and storing atmospheric carbon dioxide and it reduces the total carbon going into the atmosphere. Controlling global warming is dependent on both the reduction of greenhouse gases and increasing carbon sequestration.

Calculate your Carbon Footprint at the Nature Conservancy’s site and see how you measure up and model what you can change to see how much you can reduce your carbon footprint.

In our industry, we recognize the valuable mitigation impacts of soil and plants, and their important role in sequestering carbon, but it’s important to consider other key choices we make which can have a meaningful impact.

Healthy soil acts as a significant carbon sink and recovering and protecting soil has the potential to sequester 5.5 billion tons CO2. More carbon is stored in the soil than in the atmosphere and vegetation combined.  Some CO2 soil optimization tips include:

• Reduce soil disturbance including tilling, when possible; untilled grassland absorbs higher levels of CO2
• Add organic matter to your soil and mulch planting beds or leave debris in the planting beds
• Plant in tight connected patterns to cover the soil fully with vegetation
• Preserve or create grasslands
• Plant trees

It’s pretty clear that the greatest green industry action we can take to help sequester carbon will be to plant and integrate a forest into our larger landscape site plans, but grasslands or mixed grass and perennial plantings can have a measurable impact. Grasslands sequester most of their carbon deep underground in their root structure, so the deeper the roots, the greater the carbon sequestration.  On the other hand, forests store CO2 in mostly wood and leaves and biomass; in a stable climate trees store more carbon than grasslands.  (UC Davis)

Everyone recalls this famous illustration showing the depth and fibrous nature of prairie plants. The deeper the roots the greater the CO2 sequestration results.

Deep rooted prairie plants for carbon sequestration

The powerhouse trio of this list includes Amorpha canescens, Silphium laciniatum, and Liatris cylindracea.

All Silphium species have rough, thick foliage and yellow flowers toward the end of summer with deep root systems up to 15’; flower stalks are tall and foliage height varies, but generally they need plenty of room and can act as statement pieces in the more designed landscape.

Amorpha canescens is a legume and therefore a nitrogen fixing plant.  Its fairly low stature makes it a friendly plant integrated with non-native species. Its flower color, texture and blue green foliage make it an attractive and elegant garden plant. 

Liatris cylindracea is a relatively short statured, sun loving native prairie plant.  Its beautiful purple flowers appear in late summer and are carried more loosely than other Liatris species which gives it a look of fun, where haphazard color dots pop up in the prairie or in a planting bed. A great mixer and plant for inter-planting and blending.

Everyone wants a beautiful landscape, but more and more often, clients’ motivation for improving their landscape, whether corporate or residential, involves more altruistic reasons such as pollinator preservation, biodiversity enhancement, saving Monarchs, or corporate sustainability values and initiatives, which can easily include carbon sequestration.

Whether your client specifically requests or is committed to reducing their carbon footprint or not, do your best to make choices which bring the global warming reduction results. Include these winning plant selections in your next project for CO2 sequestration success.

ARTICLE SOURCES

https://science.nasa.gov/climate-change/what-is-climate-change

https://www.ipcc.ch/site/assets/uploads/2018/02/ipcc_wg3_ar5_summary-for-policymakers.pdf

https://palebluedot.llc/carbon-copy/2015/7/16/the-carbon-footprint-of-a-lawn

https://www.nytimes.com/2012/12/04/science/how-many-pounds-of-carbon-dioxide-does-our-forest-absorb.html

https://www.usgs.gov/faqs/what-carbon-sequestration