EARTH DAY – The Regenerative Powers of Plants

Devastating disasters like wildfires not only affect the community of people who live there but also the fauna and flora that makes the area so unique. The regenerative powers of plants are seen after a wildfire in forms of blooming wildflowers and sprouting green shoots from the base of burnt trees. The different ways plants can regenerate and recover ensures the rebounding of a healthy natural community.

giant-flowered phacelia (Phacelia grandiflora)

Seed bank

Dormant seeds that are stored in the ground start to sprout after wildfires clear the vegetation. This allows the seed bank to become exposed to daily warming and cooling of the soil that’s newly exposed to sunlight after removal of vegetation and litter. The exposure to sunlight provides UV radiation in the upper soil layer and chemicals in smoke or ash are dissolved in rainwater following fires. All these steps create the perfect environment for the seed bank to sprout. Examples of plants that grow from a seed bank are fire followers, which are wildflowers that bloom after a fire, such as giant-flowered phacelia (Phacelia grandiflora) and lupines.

Lupines

Deep, extensive root systems

New growth from a Joshua tree rhizome

Another way for plants to regenerate after a fire is through the root or rhizome system. The fire burns vegetation above ground but the underground root system is not damaged. Regrowth can occur by sprouting from the roots. Examples of plants that re-sprout from the roots are willows, cottonwoods, and mulefat.

Rhizomes are underground stems that grow horizontally and can re-sprout upwards even when the main plant is damaged or dead. Rhizomes come in all different sizes, from grasses to Joshua trees.

Joshua tree pups growing next to dead trees

Epicormic buds

Trees can bud new branches through epicormic buds. Epicormic buds are dormant buds under the bark by the base of the tree. Branches sprout when the fire damages the crown or upper part of the tree. Oak trees regenerate through epicormic buds.

New growth at the base of an oak woodland

The extent of regeneration is based on ideal conditions after a wildfire. A wet winter season is paramount for a successful regrowth. The Angeles National Forest after the Station fire (2009) and the Santa Monica Mountains after the Woolsey fire (2018) experienced a regeneration of healthy habitat due to the wet winter that followed those fire seasons. The area of the Bobcat Fire (2020) may not experience the same rate of regrowth due to a dry winter and spring this year.

Multiple fires in short succession is harmful and doesn’t allow for regenerated vegetation to become established or mature. A seed bank may not be replenished and certain species may not be able to grow back. This also changes the habitat type and allows for invasive plants to dominate the area and prevent native plants from growing back. Multiple fire damage to an oak tree can eventually kill the tree.

Mariposa lilies

There are many ways we can help nature to regenerate and be resilient.

  • Don’t pick wildflowers during the springtime. This will allow for seed bank to replenish.
  • Plant native plants. Invasive seeds can make its way into open space through winds and birds.
  • Don’t hike off trails, or better yet—stay out of burned areas until they recover.
  • Don’t try to speed up the process by introducing seeds in an attempt to “revegetate” the site. A lot of non-native plants get introduced this way, and the seeds that are already present in the seedbank will germinate anyway once the rains arrive.

Pictures: Joseph Decruyenaere, Iris Chi

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