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Fire Effects on Vegetation. September 13, 2006. Tallgrass Prairie: TTYP. First, think to yourself. Write down any causes, effects, and mechanisms that explain this landscape. Then, discuss with a partner and be prepared to share with the class. Fire in Tallgrass Prairie. - PowerPoint PPT Presentation
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Tallgrass Prairie: TTYP
• First, think to yourself. Write down any causes, effects, and mechanisms that explain this landscape.
• Then, discuss with a partner and be prepared to share with the class.
Fire in Tallgrass Prairie
• Primary role in maintenance and development
• Alteration in physical environment, particularly the litter layer
• Changes in resource availability, rapid regrowth
• Plant level mechanisms• Human management and the importance
of timing
Fires Effects on Vegetation
• Fire alters the physical environment through removal of live and dead plants from the community
• Selectively eliminates part of the plant community
• Other plant species are unchanged or have adaptions for regrowth – Thick bark and self pruning of lower branches (Jack pine,
Ponderosa pine)
• Any plant can be killed by a fire of sufficient severity
Understanding the Plant Response
• Temporarily reduces resource competition– Moisture, nutrients, and light
• Plant adaptations based on strategies of resource allocation
Mechanisms of Re-vegetating
• Vegetative re-establishment
• Seed Survival– Soil stored– Canopy stored
• Seedling persistence
• Seed dispersal
Vegetative: Plant Resource Allocation Comes in Many Forms
• Part of an individual plant survives and fire stimulates resprouting
• Aboveground and belowground resources– Dormant buds insulated by bark– Root collar sprouts i.e. oaks– Lignotubers; swellings at the base/root collar
of shoots of shrub species i.e. manzanita– Root suckering from adventitious roots; roots
are formed from stem tissues i.e. aspen
http://www.nccpg.com
Vegetative: Another
Perspective
• Classification based on the position of the perennating buds relative to the soil surface
• What organ is missing?
Geophytes
BBasal Meristems
Example: Fire Effects in Tallgrass Prairie
• Decrease in woody species– Exposed apical meristems
• Basal meristems in grass
• Protected vegetative growth– Large mass of perennating organs
belowground; high root to shoot ratio
Seed Survival
What advantages does a post-fire environment present for seed germination
and seedling survival?
Mechanisms for Seed Survival
• Seed protection from fire
– Enclosure within fruits in the plant canopy– Seed bank survival
• Seed coat (scarification), i.e. tallgrass legumes• Seed burial
• Seed dispersal– Species killed by fire and seeds don’t survive– Seeds from outside sources
Seed Protection: enclosure within fruits
• Serotiny - Cone scales are held closed by resinous material and it melts out by the heat of fire and cause to release seeds
– Jack pine, Lodge pole pine
Seed Protection: soil seed bank
Tradeoff between survival of seeds from fire and germination of seeds in different depths (Whelan 1995)
Seedling Persistence
• Early belowground resource allocation, fast growth post-fire– Longleaf pine grass stage
Fire Regimes and Vegetation
• Timing– Resistance to fire is low during reproductive
stage of plants and high with greater carbohydrate reserves
• Severity
• Duration and Extent– Dispersal limitations
Community Response
• Mortality and response of plants to fire is differential among plant species and plants of different age/developmental stage
• Fire can shift plant community structure and composition
• Example: Tallgrass prairie– Spring burn has differential influence on cool
and warm season grasses