Final Flashcards
Describe the tradeoff between high-light growth and low-light survival.
Trees that allocate more resources to growing quickly (high-light growth) are also less fit to survive in low-light conditions for a considerable amount of time, whereas trees adapted to surviving under low-light conditions often grow very slowly whether or not in full sun.
What years do competition and self-thinning dominate secondary succession in a temperate forest?
20-80
What characteristics give shrubs the advantage over trees in tundra and arid regions?
Efficiency (greater leaf/root:stem; horizontal growth), damage resistance (flexible, more points of regrowth), drought resistance (short stature, more hydraulic tissue by weight), rapid reproduction times.
P mineralization is generally (high/low) in tropical forests. Why?
Low; tropical soils are old and leached, so P is often limiting.
What type of rocks result in more acidic soils?
Igneous
Major differences between trees and other plants.
-Environment mostly dominated by other trees.
-Long-lived: requires plasticity, many chances for recruitment.
-Large: physical support, wind, long-distance transport of nutrients.
What are the main characteristics of the climax theory of succession?
Assumes that succession is orderly, predictable, deterministic, and directional towards a particular stable/normal state.
Assumes that succession is driven by biotic interactions.
Assumes that succession ultimately results in a climax self-reinforcing state.
The “fight or flight” hypothesis regarding tree responses to stress.
Most trees “fight,” investing more energy in growth/survival, disregarding allocations to reproduction. Some trees use “flight,” disregarding growth/survival to prioritize reproduction (usually only when there is little chance of survival).
What limits tree distribution at the upper treeline in montane forests?
Low temperature. Short, cool season prevents wood formation.
Why do trees in tropics produce 100x more seed than trees of similar size in cool/dry environments (much more than can be explained by NPP)?
More intense species interactions with predators or competitors may favor higher investment in reproduction.
What limits tree density in savanna woodland biomes?
Disturbances (fire/herbivory)
Disadvantages of vegetative reproduction.
Limits long-distance colonization, no genetic variation, reduced adaptation to change.
Advantages of simulation models for studying forest change.
Able to model all scales (stand/tree level to global), able to model long-term dynamics (very slow in real life).
Factors causing fire heterogeneity.
Heterogeneous landscapes, heterogeneous fuel distribution, daily fluctuations in fuel moisture, variable weather patterns.
Ancestral angiosperms were probably pollinated by ______.
Beetles
Main groups of woody plants in tropical forests
Dipterocarpaceae (major canopy group), palms (major sub-canopy group), lianas.
Importance on temperate forests in global C fluxes.
~11% global biosphere C stocks, ~30-40% global ecosystem uptake.
In tropical forests with more annual months of drought, what type of trees do you expect to see more of?
Deciduous
Strategies to attract or capture pollen.
Enhancing pollen capture and attracting pollinators.
Key attributes of disturbances.
Spatial scale/extent, temporal frequency, intensity/severity
Montane forests commonly have characteristics of more northerly forests. For every 1000m gain in elevation, temperature change is similar to ____ degrees of latitude north.
5
How do biological feedbacks in tropical forest biomes enhance their diversity?
High tree diversity may drive accelerated speciation rates, because there are more niches and habitat types.
What rocks result in relatively high fertility?
Sedimentary
The twin challenges of pollination.
Overcoming pollen limitation, and getting the right kind of pollen (usually outcrossing)
If conifers are better adapted to acidic soils, why are they more vulnerable to acid deposition?
OM inputs high acidity, sandy soils vulnerable to leaching, low soil fertility/cycling.
Major modes of spatial seed dispersal.
Gravity, wind, ballistics, water, animals.
How are boreal forests responding to climate change?
Overall more biomass, more trees in existing boreal forests. But migration not keeping up with changing climate; reduced cover at warmer edge (logging, fire) not fully compensated by northern shift.
Optimal pH for most ag plants.
6-7
How can fire suppression affect community succession?
High fuel loads cause severe fires that expand shrubland or convert forest to shrubland.
Absence of fire in grasslands allows invasion by woody plants.
Male/female flowers on separate plants
Dioecy
What type of rocks result in the fastest soil development?
Sedimentary
What rocks have similar fertility and soil development to their parent material?
Metamorphic
Self-thinning law
As young trees get larger, they get crowded and most die. Greater average tree size equates to lower stand density.
Disturbances common in tropical forests
Treefall gaps, hurricanes, fire, logging & road-building, conversion for agriculture, abandonment of plantations and pasture.
Why does succession happen quickly in smaller disturbed patches of tropical forest?
Undisturbed communities nearby provide access to colonizers, positive diversity effect on sapling survival, positive effect of nurse trees on sapling survival.
How is tree growth affected by drought at high elevation in CA?
Increased.
In soil formation, translocation.
Movement of organic/inorganic materials laterally or horizontally.
Composite provenancing
Replanting forests with trees from multiple sources to increase genetic diversity.
Globally, agriculture is shifting (to/from) the tropics.
To
When water/nutrients are limited, trees generally invest (more/less) belowground.
More
A major sub-canopy functional group in tropical forests.
Palms
The “climax” concept of succession
Change is orderly, predictable, and directional towards a particular “normal” stable state.
What soil water is available to plants?
Capillary water, held in micropores.
The most important variable affecting fire.
Fuel moisture
Why are tropical soils low in SOM?
High decomposition rates.
Dryness of atmosphere
Vapor pressure deficit
What traits enhance dominance early in succession?
Dispersion rates (ability to colonize quickly) and rapid growth under high-light conditions.
The forms of species interactions.
Tolerance, facilitation, inhibition
Results of CAST (Climate-Adapted Seed Tool) experiment.
Lower elevation/latitude seed sources performed better than or equal to local sources for reforestation.
Succession
Community change or recovery after disturbance
What type of rocks result in relatively low fertility?
Igneous
In soil formation, types of inputs.
Deposition, organic matter
What factors have a particularly strong influence on the adult stage?
Fire, wind, disease.
State-transition model: which boreal forest community dominates after a long fire-free interval, resisting further succession?
Conifers
When trees reach the canopy firsts and receive a disproportionate amount of light, shading slower-growing competitors.
Overtopping
What are the main life stages of a tree?
Seed -> germination -> seedling -> juvenile -> adult (reproductive)
What factors have a particularly strong influence on the juvenile stage?
Fire, herbivory/browsing, competition.
The two broad bands of forests.
Tropical and temperate-boreal
The four key processes in soil formation.
Inputs, losses, translocations, transformations
Degradation of an ecosystem that leads it further from climax and renders it temporarily incapable of supporting climax vegetation. Often involves soil damage.
Regression
Replanting forests with trees from multiple sources to increase genetic diversity.
Composite provenancing
How do trees in very cold areas respond to drought?
Often increases growth.
Sun or gap-seeking palms armed with hooks/barbs used as grappling hooks.
Rattans
A population.
A group of organisms of one species that is demographically distinct.
How are hot/dry forests likely to respond to a warming climate compared to cold/wet forests?
Growth rates likely to decrease in hot/dry forests and increase in cold/wet forests.
Following a severe rain event, how will streamflow of a clearcut watershed behave differently to a natural watershed?
Higher peakflow, shorter time to peakflow and lower baseflow.
Monoecy
Male/female flowers on same plant
(Biotic/Abiotic) limitations are more common early in succession.
Abiotic.
What traits enhance dominance later in succession?
Ability to survive under low-light conditions (growing underneath canopy) and the ability to cast deep shade (shading out competitors).
What years does transition to mature forest dominate secondary succession in temperate forests?
80-150
Succession: how do biotic interactions affect the community assembly?
Interactions between species limit which species can persist.
Major hypotheses to explain masting.
Predator satiation and starvation cycles, need to store up resources for seed crop, environmental cues.
Strategies to enhance pollen capture.
Physical structures for wind-carried pollen, and timing of flowering vs. leafing out.
In a single environment, there can be multiple self-reinforcing states that are resistant to change rather than a single climax community.
State-transition model of succession
Major characteristics of savanna woodland biomes.
High summer rainfall, high productivity. Trees low density, grasses continuous.
Significance of surface fuels.
Most important influence on fire spread and behavior.
What stage in secondary succession in temperate forests dominates years 150-1200 and beyond?
Old-growth or “steady state” forest.
Tropical forest trends.
Smaller, simpler, steeper, emptier.
Succession can follow multiple pathways determined by random forces and past history.
Stochastic succession.
The distance distribution of wind dispersal depends on what factors?
Terminal velocity and uplift
What influences the prevalence of fire in a particular landscape?
Fire environment triangle: fuel, weather, topography
Sources of uncertainty regarding the future of CA forests.
How high [CO2] goes, how precipitation will respond, and how plants will respond.
In soil formations, types of transformations.
Weathering, aggregation, decomposition
Features of bird-pollinated flowers.
Tubular, nectar deeply hidden, little or no scent, often red.
Most mortality in CA’s driest forest areas have been the result of ______.
Bark beetles that attack weakened trees.
How does a warming climate affect subalpine forests?
Opens up new habitat above existing treeline.
(Biotic/Abiotic) limitations are more common later in succession.
Biotic.
Disadvantages of using paleoecological models for studying forest change.
Unable to observe short-term changes, difficult to predict short-term effects of climate change.
