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Forestry Exam
| Question | Answer |
|---|---|
| Stand Development | changes in forest structure over time following disturbance |
| Cyclic (suspended) Pathway | sucessionary pathways that are repeatedly disturbed and thus never approach their climactic endpoint (Jackpine forests) |
| Intermediate Disturbance Hypothesis | species richness is the highest at intermediate frequencies or intensities |
| Disturbance Regime | set of disturbance characteristics for a specific ecosystem |
| Frequency | inverse of return interval, often expressed as probability of an event happening |
| Point Return Interval | the average time between disturbances at a given location |
| Severity | the impact to the ecosystem a storm produces |
| Intensity | the physical force of the disturbance |
| Stress | a persistent episode of suboptimal conditions. Can be reversible |
| Disturbance | a more or less discrete event that alters vegetation structure, composition, or ecological processes. They almost always destroy living plant material and are not referred to as catastrophic events |
| Relay Floristics | Concept that species replace each other through each stage because they change the environment such that it is more suitable for the next species. Creates predictable succession pathways |
| Clements Succession Model | plant communities are super-organisms. After disturbance, vegetation always recovers and moves towards climax with a predictable sequence and species composition |
| Gleasons Succession Model | succession depends on the behavior of individual species. Composition of pant communities is unpredictable, and plant distributions are unpredictable |
| Initial Floristic Composition | nearly all species are present at the start of succession |
| Succession | directional shift in species composition over time |
| Thunderstorm Downburts | powerful downdrafts of wind within a thunderstorm that spread out quickly once they reach the ground. Causes trees to fall in any direction because of the vortex |
| Derechos | extensive bands of rapidly moving straight-line thunderstorms |
| Hurricanes | violent winds with circular movements that originate over tropical waters |
| Nor'Easters | complex winter storm systems that develop on the east coast |
| Salvage Logging | post-disturbance harvesting to mitigate economic losses and reduce the risk of fire |
| The Mutch Hypothesis | fire-dependent plant communities burn more readily than non-fire dependent communities because natural selection has favored the development of characteristics that make them more flammable |
| Surface Fire | fire that consumes surface litter (fine fuel) and above ground herbs and shrubs |
| Ground Fire | smoldering fire that burns slowly through the subsurface OM underground |
| Crown Fire | fire that burns through tree crowns |
| Passive Crown Fire | energy to keep the crown burning is provided by the surface below. Dependent on surface fire |
| Active Crown Fire | crown and surface fires spread simultaneously, surface fire ignites the crown, and the crown preheats the surface |
| Independent Crown Fire | crown fire advances independent of the surface fire where strong winds bend the flames and preheat the next crown. Highest intensity, difficult to control |
| 4 Factors Influencing Natural disturbance | Agents, Magnitude (intensity and severity), Spatial Aspects (size, patchiness) and temporal aspects (point return interval and frequency) |
| Disturbance Interactions... | disturbances interact producing different outcomes than what would be assumed based on knowledge of individual disturbances |
| 8 Natural Disturbance Agents | Wind, insect outbreaks, ice storms, fire, landslides, flooding, volcanism/earthquakes and drought |
| 7 Natural Stress Agents | Competition, herbivory, disease, pollution, invasive species, climate change, drought |
| 4 Ways to identify past disturbances | GLO surveys, paleoecology methods (charcoal), fire scars and historical documents |
| How does an increase in tree density help against wind? | Increase in tree density creates a crown buffer for mutual protection from the wind |
| How are solo tree species protected against wind? | Solo trees can detect windthrow and increase taper to protect themselves |
| 5 Adaptations to fire | Cone serotiny, adventitious buds, grass stage, thick bark to protect the cambium, the mutch hypothesis |
| What causes fire scars? | Fire scars are from surface fires that form a "chimney" effect by creating a vortex that draws the flames up on th eleeward side of the bark, killing a portion of the cambium |
Created by:
SkylerG