Effects of fire on plants
Fire creates opportunities for plant growth by burning debris on the forest floor and releasing nutrients into the soil. Fire also opens up gaps in forests, creating more light for tree seedlings, shrubs and other plants that may not thrive under a shady forest. For trees and shrubs that survive the fire and are uninjured, growth may increase due to the additional nutrients and light and reduced competition from dead plants in the fire.
Plants have different adaptations to fire. Some types of trees have thick bark to protect them from the heat of the fire, or may have their branches high up, out of the reach of the fire. Other plants may die in the fire, but have seeds in the ground or deposit them from cones during or after the fire; many seedlings must become established for a few to survive to adulthood! Other plants may regrow from deep roots or the base of their stems. Aspens usually regrow from their network of lateral roots.
Some shrub species, such as the common manzanita, will readily sprout after a fire from a soil seed bank, the seeds stimulated to sprout by the heat of the fire. Many herbaceous plants can also grow from seeds in the ground, or sometimes regrow from deep roots. Conifers store seeds in cones and some species such as lodgepole pine have increased seed release after fire. Most pines need open, sunny areas for their seedlings to root and grow. In forests without fire for many decades, shade-tolerant firs are becoming more common and can gradually replace pines, which need open, sunny conditions.