Post-Fire Restoration

Overview

In this lesson, we will learn about different actions we can take to help forest ecosystems recover after damaging fires.  Students will understand that human actions can be both harmful and beneficial to ecosystems.  They will also be empowered to participate in restoration projects themselves.

Learning Outcomes

Students will know the following:

• Techniques used in post-fire restoration to stabilize soils and replant trees
• The typical steps in the process of post-fire succession
• Different types of ecosystem services that forest ecosystems provide and fire can impact

Students will understand the following:

• When post-fire restoration is necessary and when it is not

Students will be able to do the following:

• Make figures to illustrate ecological concepts

Essential Questions

• When fire disturbs ecosystems, what can we do to help forests recover?

NextGen Science Standards

• MS-LS2-2 Ecosystems: Interactions, Energy, and Dynamics
  • Construct an explanation that predicts patterns of interactions among organisms across multiple ecosystems.
• MS-LS2-4 Ecosystems: Interactions, Energy, and Dynamics
  • Construct an argument supported by empirical evidence that changes to physical or biological components of an ecosystem affect populations.
• MS-LS2-5 Ecosystems: Interactions, Energy, and Dynamics
  • Evaluate competing design solutions for maintaining biodiversity and ecosystem services.

Materials

• Approximately 5 pounds of clay soil
• Approximately 5 pounds of compost or potting soil
• 5 gallon bucket
• Native grass seeds
• Water
• Baking sheet

Glossary

• Burn scar: an area that has experienced a wildfire
• Contour felling: an approach to restoration in which trees are cut to lay perpendicular to the slope to catch soil that is being eroded
• Ecological degradation: Disruption of ecological functions such that the viability of the ecosystem is undermined
• Ecosystem restoration: An ecosystem management approach in which humans intervene to repair ecosystem structures and functions that were negatively impacted by disturbance
• Habitat: the places where plants and animals get what they need to survive, including food and water
• Mature forest: a forest that has not experienced disturbance for enough time that its structure has stabilized despite internal changes
• Pioneer species: species that are first to grow in an area that has undergone disturbance
• Runoff: Water that flows over the surface of the land without seeping into the soil
• Succession: the process by which pre-disturbance structures and functions are re-established in an ecosystem that has experienced disturbance
• Watershed: An area where all the precipitation that falls on it goes into the same waterways

Activating Strategy

Time: 15 minutes

Have students make seed balls with a mixture of seeds, clay, and compost. They are a simple and effective way to restore vegetation in areas with limited access or challenging soil conditions.

1. Add water gradually to clay soil and mix until the clay becomes pliable but not too wet. Aim for a consistency that is easy to shape, a bit like playdough.
2. Add compost or potting soil to the clay. Use enough to create a mixture that holds its shape when rolled into a ball. The compost or soil provides nutrients for the seeds to grow.
3. Sprinkle your choice of native seeds into the clay-soil mixture. Use enough seeds to ensure good coverage when the seed balls are dispersed. For northern New Mexico, appropriate species could include blue grama, sideoats grama, western wheatgrass, and Indian ricegrass.
4. Thoroughly mix the seeds into the clay-soil mixture.
5. Take a handful of the mixture and roll it between your palms to form a ball. The size of the seed ball may vary, but aim for a diameter of around 1 inch.
6. Place the formed seed balls on a tray or surface to dry. This can take several days or up to a week. Once dry, store the seed balls in a cool, dry place until you are ready to use them.
7. To use the seed balls, simply disperse them in the desired area by tossing or placing them on the ground. The rain, watering, or natural moisture will dissolve the clay, releasing the seeds into the soil. Over time, the seeds will germinate and grow into new plants.

Learning Approaches

Time: 15 minutes

Whether a wildfire has positive or negative ecological impacts depends on the fire regime of the ecosystem that is burning and the intensity of the fire.  Low intensity fires that move quickly through an area, remaining on the ground without burning the tree canopy will typically be beneficial, and no active restoration is necessary.  However, if a high intensity fire burns in an area that is not adapted to it, ecological degradation is likely, resulting in reduced habitat area, increased erosion, and significant loss of plant life.

As we have discussed, disturbance is a fundamental part of ecosystems.  Succession is the natural process by which ecosystems heal themselves.  After a fire, a pulse of nutrients is released, and certain plants grow quickly in the open burn area.  These sprinters are known as pioneer species.  In the forests of northern New Mexico, these can be grasses (like blue and sideoats grama), followed by shrubs (like Gable oak), and certain trees (like aspen).  These species are typically quick growing, require lots of sunlight and suffer in the shade of other trees, but fairly hardy to the hot and dry conditions in a burn scar.

These pioneer species change the environment in the burn scar.  They enrich the soil with organic matter that the fire had burned.  They can provide shade so the soil can retain moisture and lower temperatures for the plants growing under them.  Gradually, other species that need wetter, shadier, and cooler conditions begin growing beneath the pioneer species in the forest understory.  These species include ponderosa pine, Douglas and white firs, and Engelmann spruce.  Eventually, as they grow, they will outcompete the quick-growing pioneer species, who begin to die out and pass their baton on to these long-distance runners: the late successional species, which typically make up mature forest.  The forest will continue to grow and eventually burn again.  Have students draw out post-fire succession over time on a piece of paper, labelling the different stages.

However, areas that are not adapted to fire or those that have experienced high burn severities will often need active restoration to recover ecosystem functions. Because of high-intensity fires’ pervasive effects on soils, water, plants, and animals, restoration will need to target the entire watershed—the area where all the water drains into a single common point—where the fire burned.

Post-fire ecosystem restoration can include several management actions:

• Restorationists can seed pioneer species. For instance, land managers can hand spread grasses.  Because they need to cover larger areas, the U.S. Forest Service spread seeds aerially from helicopters.  This, along with mulching, helps limit erosion, control flooding, and restart succession.
• Restoration can also involve stabilizing streambanks with rocks and logs. Because runoff will typically increase after wildfire, streambank stabilization can help prevent erosion.
• Contour felling is another approach to controlling erosion by cutting down burned trees so they lay perpendicular to the slope, capturing eroded sediment.
• Several years after the fire, once the soil is stabilized, reforestation efforts can involve planting tree seedlings. Planting trees right away is unlikely to be successful because of the harsh environmental conditions in the burn scar.

These actions can ensure they can continue providing benefits to people, called ecosystem services.  There are four main types of ecosystem services:

1. Provisioning services: Tangible benefits ecosystems provide us that we can use and consume directly (e.g., timber, food, medicine, drinking water)
2. Regulating services: Ecological functions that control other ecosystem processes so they are not too much or too little (e.g., flood control, water filtration, erosion control)
3. Cultural services: Intangible benefits ecosystems provide that still benefit us through our experiences (e.g., education, recreation, aesthetic beauty)
4. Supporting services: The functions that allow all the other services to be maintained (e.g., productivity, pollination, biodiversity)

Summarizing Strategy

Time: 15 minutes

Have students brainstorm and classify different ecosystem services that they can identify from their neighborhoods and what benefits they derive from these services

Assessing Strategy

• Students correctly label the different stages of post-fire ecological succession
• Students correctly categorize ecosystem services