Understanding Plant Traits
This page introduces the plant traits that influence how species respond to fire, including traits that aid plants in resisting fires and traits that help plants persist and regenerate after burning. Understanding such traits allows us to gain insight into the ecological strategies that support plant fitness to inhabit fire prone landscapes, and highlights the resilience of vegetation under a changing climate and in changing fire regimes.
Below is a list of traits, their functions and their associated traits along with some images to show some examples. These traits are found in the different species detailed within this website.
Traits that aid survival through fire
Trait:
Resprouting through aerial buds.
Function/Adaptive value:
Production of new vegetative biomass after a fire from buds in the surviving aerial stem. Resprouting can occur from the surviving apical bud (‘apical sprouting’) or from accessory buds on the stem (‘epicormic resprouting’).
Associated Traits:
Above-ground resprouting is enhanced by- or dependent on- traits that protect buds from lethal flaming temperatures (e.g. thick insulating bark, sunken stem buds), In surface-fire regimes, buds held high above the ground (achieved by rapid vertical growth) can escape being scorched (Higgins, Bond and Trollope, 2000; Burrows and others, 2008).
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image credit C. Belcher - Sequoia sempervirens, California
Trait:
Resprouting from basal buds.
Function/Adaptive value:
Production of new vegetative biomass after a fire from buds at or just below the soil surface. Resprouting may occur on specialised organs such as lignotubers.
Associated Traits:
Traits that limit heat exposure to basal buds during fire will enhance resprouting (e.g. leaf sheaths, stem bases, bark). Resources for resprouting can be provided by storage structures such as lignotubers.
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image credit C. Belcher, - Ulex europeaus, Dorset
Trait:
Resprouting from below ground buds.
Function/Adaptive value:
Production of new vegetative biomass after a fire from buds below the soil surface (and therefore protected by an insulating layer of soil). Resprouting occurs from a variety of woody and herbaceous structures (rhizomes, roots, root suckers, xylopodia).
Associated Traits:
Resources for resprouting can be provided by storage structures such as corms, bulbs, and tubers.
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image credit C. Belcher - Erica cinerea, Dorset
Trait:
Thick outer bark
Function/Adaptive value:
Protection of stem plant tissues (phloem, xylem and meristems) from lethal temperatures. Bark is a very good heat insulator, and the degree of insulation is proportional to bark thickness.
Associated Traits:
Thick bark is associated with branch shedding (or self-pruning) in Pines under surface fire regimes. This prevents surface fires from climbing into tree crowns, which would result in tree mortality (He and others 2012).
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image credit C. Belcher - Pinus sp. Dorset
Trait:
Low flammability.
Function/Adaptive value:
Low tissue flammability prevents plant biomass burning. Diverse traits result in low flammability, including a low biomass surface area: volume ratio (e.g. thick branches and leaves), high biomass moisture content (e.g. succulence) and the removal of highly flammable biomass (e.g. self-pruning of dead lower branches in Pines).
Associated Traits:
Low flammability may be associated with other traits that are associated with protection from high burning temperatures (e.g. thick bark). Otherwise, non-flammable plants are unaffected by fire and so do not possess traits associated with enhanced survival or reproduction through fire.
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image credit C. Belcher - Pinus sp. Dorset
Traits that aid reproduction and recruitement after fire
Trait:
Heat stimulated germination.
Function/Adaptive value:
Seed dormancy is broken by the heat of the fire, and germination is enhanced. Heat breaks a water-impermeable seed coat which imposes dormancy. This increased permeability of the seed coat allows imbibition and the induction of physiological processes leading to germination.
Associated Traits:
Seed bank that persists through fire either by possessing traits that make them invulnerable to heat-shock or that seeds are stored in protected structures or beneath soil.High flammability of the adult plant may enhance the heat shock experienced by seeds, and their degree of germination.
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image credit C. Belcher - Ulex sp. Dorset
Trait:
Smoke stimulated germination.
Function/Adaptive value:
Seed dormancy is broken by the chemical products of biomass combustion, which act as internal stimuli to induce germination. A diverse set of combustion-related chemicals have been implicated in smoke-stimulated germination.
Associated Traits:
Seed bank that persists through fire either by possessing traits that make them invulnerable to heat-shock or that seeds are stored in protected structures or beneath soil.
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image credit C. Belcher - Ulex sp. Dorset
Trait:
Serotiny.
Function/Adaptive value:
Recruitment from dormant canopy-stored seed banks (closed cones or fruits, in which seeds are protected from the heat of the fire). Opening of these structures occurs after fire, allowing dispersal which is followed by rapid germination.
Associated Traits:
High flammability of the adult plant may enhance the likelihood of seed banks experiencing sufficiently high temperatures needed to open.Branch-retention (a flammability-enhancing trait) is linked to serotiny in pines and allows fires to climb into the canopy where seed banks are (He and others 2012).
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image credit C. Belcher - Pinus sp. Dorset
Trait:
Fire stimulated flowering.
Function/Adaptive value:
Profuse flowering after fire. Flowering is limited between fires, or entirely absent.
Associated Traits:
Fire-stimulated flowering requires rapid resprouting of biomass following fire.
Trait:
Increased flammability.
Function/Adaptive value:
For a plant, high biomass flammability may increase the likelihood of ignition, combustion temperatures and rate of fire spread. High flammability is related to the chemical and physical properties of the plant’s biomass, including its amount, arrangement, density, moisture content and the presence of highly combustible compounds. High flammability may enhance post-fire resprouting, if it aids the removal of any shading biomass and/or if it reduces competition from more heat-sensitive species. It also may enhance recruitment in species that have heat-stimulated germination and flowering.
Associated Traits:
Heat-stimulated flowering and/or germination may be enhanced by high plant flammability. Species that are shade intolerant may benefit from being highly flammable, which aids in the removal of dead and woody biomass in order to maintain high light availability. In resprouting species, high flammability will likely be associated with the protection of resprouting buds from high temperatures (e.g. by bark or other plant structures, or a layer of soil).
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image credit C. Belcher - Pteridium aquilinum, Dorset
