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56 Cards in this Set
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synecology |
study of groups of individuals/population |
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Population |
group of interbreeding organisms living in some particularplace more likely to breed w/in a population than outside of it |
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genecology |
study of gene frequency within a population |
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species |
group of genetically, morphologically, and ecologically similar pop.s that are reproductively isolated |
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metapopulation |
group of spatially separated populations that interact |
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introgression |
Introduction of new traits due to hybridization and repeated backcrossing Engleman/white spruce ex. No reproductive isolation (engleman in mts, white in boreal) -hybridize in areas of overlap→individuals have a mix of traits |
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Red/black spruce ex of hybridization |
Red in appalachian mts, black in boreal No hybridization -- have coexisted for thousands of years, would have hybridized if they could have |
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Sitka spruce example -- provenance study |
Collected seeds from different latitudes across W. US and Europe, planted them in Germany → time of bud-set was due to genetics, not a response to light → were only adapted to their own habitat |
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Pitch Pine ex. |
NJ pine barrens have a lot of fires in the top part of the plains Find more pitch pine with cone serotiny (need heat to release seeds) in this area, fewer as you move away -- controlled by fire frequency |
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Redwood ex -- age structure |
Study said you can sustainably cut down young trees (3 ft in diameter) and keep the "cathedral" -NOT true because you don't know the values of survivorship and graduation |
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life stage model of trees |
seed→ seedling→ sapling→ mature→ veteran |
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Almendro forest |
There are few sub-adults because few are added to it and those that are grow out of it (into canopy) quickly |
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Mangrove forest |
Germinates in canopy, falls → high seedling survival, low sappling success, once it reaches canopy it's fine |
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Forest decline |
a complex disorder involving stresses on a tree population that results in decreased growth and increased mortality ex. bark beetles |
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Manion's decline spiral concept |
pre-disposing factors: chronic stresses -competition, long-term enviro. factors inciting factors: damaging events -severe drought, defoliation, bark beetles |
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Decline hypothesis |
The greater the predisposing stress,the more likely a tree will not recover from an inciting stress event |
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self-thinning |
populations decline in density as biomass increases -ex. pin cherry |
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Succession |
directional change through time in thecomposition and structure of the biotic community |
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Succession at Glacier Bay |
use chronosequence - substitute space for time 1. lichens, mosses, fire weed → decay and add OM 2. Dryas - fixes Nitrogen 3. Alder (shrub) - fixes nitrogen 4. cottonwood - shades out alder 5. sitka spruce - shades out cottonwood → mature spruce forest, sometimes hemlock |
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Reductionist appraoch against succession |
Seems to be a balance b/w changing soils and inhibition of seedlings, NOT each species enables the next Reductionist approach: each species occurs based on its own traits and luck -find permanent alder thickets where cottonwood should be expected |
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Precepts of succession |
1. Dominant plants exert controlling influence on organism distribution by changing local environment 2. Depends on state of environment at time of initiation, specifically disturbance regimes |
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Retrogression as opposed to succession |
Succession implies subjective end goal Alaska floodplain -"normal" succession (which leads to white spruce forest) only happens when floods lay down new sediment (alluvial terraces) -if no flood, sphagnum cover whole ground and black spruce + moss dominate → lower productivity, eventually a fire |
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Disturbance |
a disruptive event that results in a large change in resource availability and environmental conditions |
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Disturbance characteristics |
1. Scale 2. Intensity 3. Frequency |
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Disturbance regime rules |
1. large-scale disturbances tend to be less frequent than small-scaledisturbances 2. intense disturbance usually do not occur at high frequency 3. large disturbances usually are more intense than small ones |
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Disturbance effect on area ex. |
Distribution of tall grass prairies is dependent on fire -prairie peninsula sticks into what would be deciduous forest climate -b/c area is flat and fire spreads |
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Interactions of distrubances |
the occurrence of one disturbance may either promote or discourageanother disturbance |
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Interactions of distrubances ex. |
Colorado Rockies - have fires, bark beetles, and snow avalanches -fire regime represses beetles for 100 yrs -beetles kill trees→ promote fire -avalanches → fire breaks |
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Factors influencing fire |
1. Fuels -- biochemistry, moisture, size, arrangement 2. Weather/climate -- lightning, past precipitation, temperature/humidity affects fuel moisture, wind 3. Topography |
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How humans affect fire |
1. ignite/avoid igniting 2. suppress/fight 3. alter fuels -- amount and arrangement |
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Frequency/intensity patterns of fires |
Crown fires - from infrequent, severe droughts -needs to be a nutrient-rich forest so there's a closed canopy surface fires - from frequent, mild droughts -selects tall trees without low branches - ponderosa pine |
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Plant traits influencing fire-vegetation interaction |
Survival - in surface fire regimes, NOT crown - thick bark (oak, pines) -bud protection (long-leaf pine -- leaves burn) Reproduction - in both types of regimes -cone serotiny, vegetative strategy, activation in seedbed Promotion traits -volatile resins, delayed decay of litter → don't know if this is a direct selection b/c you need whole stand to have this for effect → could be resins inhibit pathogens |
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Niche assembly rules |
restrictions on the presence orabundance of one species depending upon the presence orabundance of other species |
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Commensalism |
benefits one, no effect on the other -ex. epiphytes - plants growing in tree canopy |
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amensalism |
hurts one, no effect on other -ex. allelopathy (walnuts secrete juglone) |
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White mountains |
Heath growing where you'd expect forest (high altitude) looks like spruce/fir are invading, but heathlands persist Contingency table shows association is non-random, and is likely due to competition |
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secondary metabolites |
biochemicals not involved in central physiological processes -- ie against pathogens |
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Difficulty in proving allelopathy |
Fern glades -difficult to prove presence, b/c need to disprove other possibilities -use contingency table, see if organisms are producing chemicals |
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Why invasive plants thrive |
Natural enemies hypothesis -- lack of species to control it -- outside niche assembly rules, can put defense energy into growth Novel weapons hypothesis -- native flora evolved resistance to native plants - invasive allelopathy is new to natives |
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Predator escape hypothesis |
Higher probability of predation/pathogens in neighborhood of mother tree, which harbors threat aligns with reciprocal replacement hypothesis |
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Hutchinson's paradox |
How is there an abundance of niches in a uniform environment (ocean)? Explained by colimitation and compensation |
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colimitation |
limitation by more than one resource |
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Compensation |
limitation in one resource/condition can be compensated by abundance in another |
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Rich site/poor site |
-In poor soils - r.s. species don't compete well for soil resources → out-competed for light - soil resources come first -In rich soils - p.s. species grow slowly and are shaded out - light comes first |
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Why pin cherry is a rich site species |
Does well in rich site (ie clear cut area) -- abundant light and soil res. Site goes from rich to poor -- pin cherry loses dominance because it can't get as many soil resources, and is then outcompeted for light hypothesis tested by adding nutrients to 15 yr old stand → pin cherry thrived |
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Leaf area dominance |
proportion of leaf area above competitors in canopy |
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Why is local community nested within larger place with more species |
Environmental filter Interspecific interactions |
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Environmental filter |
conditions (via disturbance legacy, soil conditions, local climate) filter out some species |
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Trait conservatism |
species carry traits from their ancestors, even those that are not functionally relevant, such that there are similarities between related taxa |
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phylogenetic clustering |
closely related species occur together b/c they have similar requirements and are living in same conditions |
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phylogenetic overdispersion |
related species diverge because niche divergence via competition |
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niche pre-emption hypothesis |
#1 dominant species gets half, #2 gets half of remaining etc |
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Regional differences in species richness due to |
favorableness effect : habitat historical effect: glacial refugia, migration multiplier effect: diversity begets diversity area effect: larger contiguous area |
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Theory of island biogeography |
Diversity represents historical balance between gain and loss of species gain = immigration loss = extinction Small island: more extinctions large island: fewer extinctions Far from mainland: fewer new species close to mainland: more new species Supports neutral theory -- says you don't need niches to explain patterns in diversity -- random factors cause community associations |
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Hubbell neutral theory -- Ecological drift |
Community structure could reflect random addition andloss of species evidence: created model of a forest -- made gap, each species equally likely to fill it - sets immigration rate to match observed → matches actual community Tested and proved that dispersal limitation is strong in most species Probably balanced with community assembly rules, just varies how much Compare shared species across an increasing distance b/w plots →Panama -- decreases, shows that there's more diversity, due to niche ass. rules →Amazon flood plain -- stays the same, shows uniformity due to dispersal limitations |
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Genetic overdispersion vs cluserting paradox |
Matter of scale -fine scale→ overdispersion due to interspecific interactions -large scale→ clustering due to environmental filter |
