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.
What years does colonization dominate secondary succession in temperate forests?
0-20
Drought/deforestation effects in tropical forests have a (lesser/greater) effect on C emissions than boreal forest wildfires.
Greater
Which is usually greater, transpiration or evaporation?
Transpiration
State-transition model of succession
In a single environment, there can be multiple self-reinforcing states that are resistant to change rather than a single climax community.
How do tropical trees avoid self-pollination?
Partly self-incompatibility, but also wide-ranging pollinators
Assisted gene flow.
Moving seed sources within recent historic range to promote reforestation.
The significance of ground fuels.
Important in terms of how fire affects soils, seeds, and large trees.
Approaches to studying forest change over long time scales.
Long-term forest plots, simulation models, paleoecological records, remote sensing.
As young trees get larger, they get crowded and most die. Greater average tree size equates to lower stand density. This describes the ______.
Self-thinning law.
What two factors primarily affect global forest distribution?
Precipitation and temperature
What must happen for a plant to sexually reproduce?
Pollinate/get pollen, disperse seeds, germinate, survive as tiny plants and grow larger.
What factors affect the large-scale patterns of tree mortality from bark beetles in CA?
Aridity and forest density.
A contiguous area that contains a number of trees that are relatively homogeneous or have a common set of characteristics.
A forest stand.
Succession in hardwood forests of NH: Which trees generally follow yellow birch and why?
Sugar maple seedlings can grow in the shade of birches, but eventually grow tall and outcompete them.
Succession in hardwood forests of NH: Which trees are most common following a disturbance and why?
Yellow birch has strong dispersal and is most likely to first colonize gaps.
General characteristics of tropical soils.
Low SOM, low fertility, high clay, high Fe and Al.
Direct effects of high [CO2] on forests.
Heightened photosynthesis, WUE, fertilization.
What natural fire regime dominates dry mixed-conifer forests in the west?
Frequent, low-severity
Most tree species in CA are expected to (increase/decrease) seed production in response to future climate change.
Increase.
The fuel layers/strata of forests.
Ground, surface, ladder, and canopy fuels.
What stage of secondary succession in temperate forests dominates the first 20 years?
Colonization
Current approaches for reducing deforestation/degradation in tropical forests.
UN-REDD (reduced emissions from deforestation and degradation) program (compensates countries for forest conservation), securing indigenous land rights.
Disadvantages of long-term forest research plots for studying forest change.
Labor-intensive; most only 2-4 decades old.
Dead fuel moisture is driven by ______.
Vapor pressure deficit
Male/female flowers on same plant
Monoecy
Features of mammal-pollinated flowers.
Wide open, dilute nectar, fruity/fermented scent, open at night, often white.
Features of beetle-pollinated flowers.
Open shape, opens during day, white/greenish, tough flower parts, no intricate shape or placement of anthers/stamens.
Factors affecting transpirations rates.
Water availability, energy (heat), leaf area index (leaf area/unit ground area, plant physiology
Under what conditions does high tree density facilitate seedling survival?
Harsh, windy conditions
Succession study in Glacier Bay, AK: What affects did the pioneer community have on new growing plants?
Facilitative: Increased survivorship
Inhibitory: Weak reduction in germination
Overall: Facilitation of woody plants
What pollination challenges face tropical trees?
Tropical trees mostly occur at low density due to forest diversity; pollen limitation
Succession study in Glacier Bay, AK: What stages were more unstable/transitory?
Pioneer and alder
Vapor pressure deficit.
Dryness of atmosphere
What scale of disturbances can increase diversity of environmental conditions in a forest and create a mosaic of different forest ages?
Medium and small-scale
What two characteristics are most important in affecting vegetation communities in fire regimes?
Frequency and severity; spatial scale less important
Cones that hold seeds until the adult is dead and the releases them all at once.
Serotinous cones
Cyclic succession
All states in the pathway have negative feedbacks that destabilize them
Moving seed sources within recent historic range to promote reforestation.
Assisted gene flow.
What scale of disturbances can create large, relatively homogeneous patches?
Large-scale
How are the effects of wind disturbances usually distributed in space?
Waves of forest regeneration
Features of bee-pollinated flowers.
Tubular flowers, nectar at base, open during day, perches, scented, often blue.
Mixed-severity fire regimes
Fire regimes characterized by a mix of surface and crown fire, and with a mixture of low, moderate, and high-severity effects.
Figs are pollinated by tiny ephemeral wasps, yet pollen is often dispersed over very long distances. How does this happen?
Wasps ride the wind then find new fig trees.
Succession study in Glacier Bay, AK: What stages were more stable?
Dryas and Spruce forest.
Janzen-Connell effects
Common trees in tropical forests experience greater pest/pathogen pressure, limiting population growth. Alternatively, rarer trees experience less pressure and faster population growth, potentially limiting extinction rates.
Significance of ladder fuels.
Important in terms of fire spread and behavior by providing a path for fire to travel to the canopy. Linked to torching or crowning.
What stage of secondary succession in temperate forests dominates years 20-80?
Competition, self-thinning
Succession: filters
Determine which species can maintain positive populations growth
Significance of canopy fuels.
Important in terms of fire spread and behavior to due torching, crowing, and spotting.
One of the world’s oldest continuously existing biomes.
Tropical moist forests
What general mechanisms determine which paths of succession are possible and drive changes along these paths?
Abiotic, biotic, history.
Succession: source pool
Regional tree community, where colonizers come from.
What resources do trees compete for?
Aboveground: Light
Belowground: Water & nutrients
Masting
Alternating years of heavy fruit/seed production and years of little or none.
How can clearcutting affect soil nutrient leaching?
Nitrate ions carry cations out with them
How are the effects of fire disturbances usually distributed in space?
Patchy and heterogeneous.
Assisted range expansion.
Moving species into newly suitable areas to promote reforestation.
Major characteristics of tropical/subtropical biomes.
No frost, very low annual variation in temperature.
Large mass seeds tend to dispersed in what way.
Vertebrate-assisted dispersal.
Other than directly intensifying fires, how can wind interact with fires to affect forests?
Reduced canopy cover from fires can increase wind speed and tree mortality.
Succession in hardwood forests of NH: What trees generally follow sugar maple and why?
Beech seedlings are even more shade tolerant that sugar maple and the adult trees cast deeper shade.
(Small/Large) seed are sometimes associated with stronger dormancy and longer seedbank persistence.
Small
What forestry practices enhance C uptake in boreal forests?
Lengthening the interval between harvests.
The base cations
Ca, Mg, K, Na (also NH4)
The importance of boreal forests in global C fluxes.
Enormous pool of C in boreal peat soils (~equal to all living tropical forests, but very slow fluxes); slow growth but large extent (~20% of global forest C uptake); growth and C uptake responding positively to increased temperatures, but may be offset by emissions from peat and other soil C.
State-transition model: which boreal forest community dominates after fire consumes the organic layer, resisting further subsequent succession?
Deciduous trees
Why is succession slow/nonexistent in large, highly degraded/disturbed patches on tropical forest?
No nearby undisturbed communities to provide colonizers, low diversity and lack of nurse trees limits sapling survival.
pH of most forest soils
4-6
What broad factors characterize a fire regime?
Spatial scale of fires, temporal frequency of fires, and magnitude/severity of fires.
Compared to old forests, N is often (more/less) available in tropical forests. Why?
More, because of rapid nutrient cycling.
Dioecy
Male/female flowers on separate plants
What general phases to forests go through during succession?
Colonization, competition and self-thinning, transition to mature forest, and old-growth or “steady-state” forest
In soil formation, types of losses.
Leaching, erosion
The adaptive significance of masting
Avoids demographic tracking by predator populations (does not cause populations to increase), predator satiation (more than the predator can consume, ensuring some seeds survive)
Serotinous cones
Cones that hold seeds until the adult is dead and the releases them all at once.
What factors limit the northern extents of temperate hardwood forests? Why?
Low winter temperatures: high surface area:mass of deciduous leaves results in more rapid heat loss compared to conifers.
Short growing seasons: Deciduous trees need time to make leaves.
Why are tropical soils low fertility?
Most of the macronutrients are already taken up by living plants; high leaching rates.
As a stand of trees grows, what happens to average size and density?
Size increases, density decreases.
Tropical forests have a (high/low) capacity for regeneration.
High
How and why does hunting pressure affect tropical forests so much?
Most tropical tree species are animal-dispersed. High hunting rates reduces recruitment rates in these species.
How can satellites and other remote sensing data be used to monitor changes in forests?
Landsat satellites can estimate forest canopy density by comparing near infrared to red light absorption (chlorophyll absorbs red light but reflects near infrared).
Hyperspectral imagery and LiDAR can estimate canopy water content. Hyperspectral imagery can also examine leaf chemical composition (nutrient levels, defense compounds, etc.).
Can use fine-scale areal imagery and LiDAR to map individual tree crowns and survival. Can train computer vision models to identify living/dead trees across landscape.
High elevation tree growth in CA is (energy/water)-limited.
Energy
If hardwoods are less tolerant of acidic soils, why are they less vulnerable to acid deposition?
Rich clay soils have high buffering capacity and nutrient retention, many species act as cation pumps and redeposit cations in litter.
What natural fire regime dominates the temperate rainforests of the PNW?
Infrequent, high-severity
Why does transpiration usually exceed evaporation?
High surface area of leaves/roots, turbulent airflow around leaves, conduits to deep moisture sources.
Succession: regression
Degradation of an ecosystem that leads it further from climax and renders it temporarily incapable of supporting climax vegetation. Often involves soil damage.
What strategies to plants use to avoid self-pollination?
Separate male/female flower parts or flowers, self-incompatibility, attracting wide-ranging pollinators
Asymmetric competition
Competition in which the “winner wins big.”
Why is dispersal especially important in the tropics?
To escape seed predators and pathogens.
What soil water is unavailable to plants?
Hygroscopic (tightly held to soil particles) and gravitational (drains out of root zone).
Indirect effects of high [CO2] on forests.
Climate change, warmer temperatures, drier climate.
In forestry, why are stands thinned if self-thinning would naturally occur?
Surviving trees are bigger, healthier, and more valuable.
What stage in secondary succession in a temperate forests dominates years 80-150?
Transition to mature forest
Rattans
Sun or gap-seeking palms armed with hooks/barbs used as grappling hooks.
What factors favor regular seed production rather than masting?
Dependence on mutualist dispersers, high nutrient resources, warm/wet environments.
Very low mass seeds tend to be dispersed in what way?
Unassisted dispersal.
Over what time scale can a tropical old-growth forest redevelop?
A century or more.
Advantages of vegetative reproduction.
Rapid local colonization, flexibility in accessing spatially heterogeneous resources, recovery from damage, survival of genotype despite death of individuals.
How does high productivity in tropical forest biomes enhance their diversity?
High energy -> high biomass/metabolic activity per unit area; more individuals, faster generations times.
Examples of facilitation and the environments they occur.
Trees can share nutrients through mycorrhizal networks.
High stand density can facilitate seedling survival in harsh, windy conditions.
A major canopy functional group in Asian tropical forests.
Dipterocarpaceae
In what ecosystems does the climax theory of succession make no sense.
Ecosystems where disturbance is internal to the system and fundamental, such as ecosystems with high-frequency fire regimes.
(Small/Large) seeds are associated with animal dispersal.
Large
Factors affecting runoff.
Rate of precipitation, topography, infiltration rate, ground cover
Stochastic succession
Succession can follow multiple pathways determined by random forces and past history.
Types of temporal seed dispersal.
Soil seed banks, canopy seed banks (serotiny), seedling/sapling banks
Change is orderly, predictable, and directional towards a particular “normal” stable state.
The “climax” concept of succession
Common trees in tropical forests experience greater pest/pathogen pressure, limiting population growth. Alternatively, rarer trees experience less pressure and faster population growth, potentially limiting extinction rates.
Janzen-Connell effects
Disturbance
Sudden or temporary environmental change that causes change in an ecosystem.
What factors may limit the utility of temperate forests for C uptake in the future?
N-limitation restricting CO2 fertilization response, insect/pathogen responses to warming, the fact that around half of the strong current C sink is due to forest regeneration (how long will this last?).
Overtopping
When trees reach the canopy firsts and receive a disproportionate amount of light, shading slower-growing competitors.
Key characteristics of fuels
How much, what form, how distributed, and how dry.
Advantages of long-term forest research plots for studying forest change.
Large enough to studying forest dynamics, including dispersal and some disturbances; remeasurement allows tracking all tree life stages; interactions of trees with other plants, animals, microbes.
Live fuel moisture is driven by ______.
Soil moisture
Advantages of using paleoecological models for studying forest change.
Ability to observe deep into the past, able to correlate climate/disturbances to vegetation responses.
How does flowering before leafing out enhance pollen capture?
Higher wind speeds around flowers
Succession study in Glacier Bay, AK: What affects did the Spruce community have on new growing plants?
Facilitative: Weak increase in germination.
Inhibitory: Strong decreases in growth, survivorship, and N, increases in predation/mortality, competition.
Overall: Highly competitive, resist transition away from spruce forest.
Succession study in Glacier Bay, AK: What affects did the Dryas/shrub-dominated community have on new growing plants?
Facilitative: Weak increases in N and growth.
Inhibitory: Strong decreases in germination, survivorship, and increases in seed predation/mortality.
Overall: Inhibits succession, but gradually gives way to alders.
Moving species into newly suitable areas to promote reforestation.
Assisted range expansion.
What degree of weathering is ideal for high quality forest soils?
Moderate, primary minerals
What major factors make tropical forests so diverse?
Age & stability, high productivity, Janzen-Connell effect (more common trees accumulate pests/pathogens, limiting population growth; rarer trees experience greater population growth, lowering extinction rates), and biological feedbacks.
What factors have a particularly strong influence on the seedling recruitment stage?
Seed predation, dispersal, desiccation, herbivory, competition, fire.
Wildfire effects on peak snowpack.
Higher mid-winter snow depth, shorter spring duration
How might the Janzen-Connell effects slow extinction rates in tropical forests?
The rarer a species is (closer to extinction), the less pest/pathogen pressure it experiences. This may give these species an advantage over more common species, boosting population growth.
How does the age and stability of tropical forest biomes enhance their diversity?
More time for species to accumulate, few big climatic changes that increase extinction rates.
Succession study in Glacier Bay, AK: What affects did the alder community have on new growing plants?
Facilitative: Strong increases in SOM, N, mycorrhizae, and growth.
Inhibitory: Reduced germination and survivorship, increased seed predation/mortality, root competition, and light competition.
Overall: Facilitates transition to forest.
Succession in hardwood forests of NH: What trees generally follow beech and why?
Large leafy canopies of beech are prone to small-scale disturbances from wind/ice, creating small gaps which yellow birch are quick to colonize.
Major characteristics of boreal forest biomes.
Short warm summers, long cold/dry winters.
Succession: how does history affect the community assembly?
Disturbances and management by people
A forest stand.
A contiguous area that contains a number of trees that are relatively homogeneous or have a common set of characteristics.
What years does old-growth or “steady state” forest dominate secondary succession in a temperate forest?
150-1200 and beyond
Disadvantages of simulation models for studying forest change.
Limited by computation (CPU & memory) and parameterization (lack of detailed data on plant performance across environments)
Besides texture, what soil characteristics affect infiltration rates?
WHC and soil depth
How does self-incompatibility work?
If pollen grain contains same S-allele as the plant it can’t fertilize the ovule.
