About The ARC
The Arizona Restoration Center (ARC) at Paradise Valley Community College is an intersection of environmental and social sustainability. The purpose of the project is to sequester atmospheric carbon dioxide within native Arizona Sonoran Desert plants and soil as well as sustainably grow food for community members within an urban setting.
It is estimated that between 50 and 60 percent of warm deserts’ CO2 storage occurs within the soil, and is projected to increase to around 63% by 2050. Studies show the average time for reestablishment of perennial plant cover following a variety of disturbances in the Sonoran Desert was 76 years. These figures combined with the current climate crisis do not allow for inaction.
Through science-based management practices, a vacant 4.4 acres of land will be transformed to a native Arizona Sonoran Desert ecosystem and community garden space. Desert ironwood (Olneya tesota), velvet mesquite (Prosopis velutina), and blue palo verde (Parkinsonia florida) will be used to increase soil nitrogen content and in turn soil organic carbon, as well as break through the caliche soil. By improving soil health and restoring part of Arizona's natural ecosystem, the ARC will become a site of learning opportunity, community connectivity, and stability for food-insecure populations.
This work is supported by the Department of Forestry and Fire Management (CCG-23-105), Maricopa County Community Colleges District Office of Sustainability, and Second Nature Inc.
The Dirt: Soil Ecology
Soil is one of Earth’s largest carbon pools, second to the ocean. As part of the atmospheric carbon cycle, carbon fluxes in and out of the atmosphere and soil through photosynthesis and soil respiration. When plants photosynthesize, they convert carbon dioxide and water into glucose and oxygen. Plants respire some of the carbon they take into the atmosphere, but some of it is stored within them (their biomass) and some of it is buried in the soil by them (carbon sequestration).
When land like the 4.4 acres we have is absent of any vegetation, it cannot actively sequester atmospheric carbon because there are no plants to complete the process. Furthermore, barren soil is at risk of wind and water erosion. Caliche soil, also known as “calcrete” is highly mineralized and compact. As a matter of fact, it is made up primarily of calcium carbonate, the same material that corals are composed of. This extremely hard soil is great at holding onto ancient carbon stores, but requires careful management to be converted into an active carbon sink through the use of new plants.
So, how do we do it? The trees for the ARC were carefully selected. Not only are they native Sonoran Desert varieties adapted for this ecosystem and tolerant of low water, high heat conditions, they fit the purpose of the project well. Aside from being beautiful, they bear both cultural significance and standout abilities to change soil properties.
All three trees (desert ironwood, blue palo verde, and velvet mesquite) are leguminous nitrogen-fixers. This means that they produce seeds in pods and fix nitrogen to soil. Nitrogen is a vital soil nutrient and can even result in higher amounts of soil carbon fixation. They all possess root systems designed to anchor them deep into the soil and eventually reach groundwater stores. Some of the trees have been planted with sand around their root balls as a natural amendment to draw water down to their root systems.
A Little Bit About Each Tree
Desert Ironwood
Desert ironwood boasts dense and strong wood that is used for construction, furniture, and woodworking. Although people may know and like ironwood for its commercial uses, its ecosystem services are underrated. Its incredibly hard wood holds vast amounts of carbon in its above-ground biomass, aside from the carbon that is fixed to the soil. As a matter of fact, ironwood will hold onto the carbon within its trunk and limbs long after its death. Studies have shown desert ironwood to have comparatively higher nesting sites than other native trees, showing that animals love it too.
Blue Palo Verde
Blue palo verde can be recognized by its blueish-green bark and beautiful yellow flowers when in bloom. One cool thing about palo verde is that it has chlorophyll throughout its trunk. Chlorophyll is one of the heroes of photosynthesis that allows plants to harness energy from the sun. This green compound being present throughout the palo verde’s trunk, limbs, and leaves enables it to photosynthesize across its entire above-ground surface area.
Velvet Mesquite
Studies have shown velvet mesquite to have unique symbiotic (mutually beneficial) interactions between its roots and the tiny creatures living within soil known as soil microbiota. These soil microbiota thrive on the nitrogen carried into velvet mesquite’s root systems. Mesquite roots form nodules (round masses) hosted by the nitrogen-fixing bacteria, which in turn make the soil more nutrient-rich for the mesquite itself and surrounding plants.
Visitor & Volunteer Guidelines
Students, faculty, staff and members of the community are welcome to visit the ARC and to volunteer for the ARC. While doing this, please:
- Be open to new information
- Be tolerant of and embrace people different from you or who have different ideas.
- Do not remove anything from the Center without asking.
- Be kind to the trees, plants and animals on the site.
- Give us notice whenever you cannot make for an event or activity you have committed to.
- Provide us feedback and suggestions.
Recent Events & Activities
AZ DFFM Grantee Showcase - 10/16/2024
STEM Talk - 03/31/2025
- Cali Mauri's presentation
ARC Workshop - 04/15/2025
- Cali Mauri's presentations
- Dr. Ken Sweat from ASU-West Desert Restoration Zone presentation
- Timara Crichlow from AZ DFFM presentation