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final Flashcards

1
Q

temperate and boreal forests - geographic distribution

A
  • predominantly in N hemisphere
  • temperature forests do occur in S.America, Australia, and New Zealand
    -in N hemisphere, coniferous forests form a broad circumpolar belt
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2
Q

temperate and boreal forests - climate

A

seasonal variation determined by temperature
TEMPERATE
- winter lows: -15 C to -5C
- frost free days; 120 to 150 days
- summer temps; 15 C to 27 C
- precipitation 500 to 1000 mm
CONIFEROUS
- winter lows: -30 C
- frost free days; 50 to 100 days
- summer temps; 12 C to 15 C
- precipitation <500 mm in summer and 100 mm snow in the winter

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3
Q

temperate and boreal forests - characteristic growth forms

A

TEMPERATE
- broad-leaved deciduous trees
- annuals and hemicryptophytes, forest floor
CONIFEROUS
- needle-bearing trees
- hemicryptophytes

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4
Q

temperate and boreal forests - characteristic species

A

TEMPERATE
- elm, ash, walnut, sugar maple, basswood, aspen, birch, maple, willows
CONIFEROUS
- white spruce, black spruce, jack pine, white pine, hemlock, cedar

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5
Q

comparison of the deciduous vs. the evergreen, coniferous habit – leaves

A

DECIDIOUS
- broad leaved
CONIFEROUS
- narrow, often needle-leafed

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6
Q

comparison of the deciduous vs. the evergreen, coniferous habit – tissue

A

DECIDIOUS
- vessels (perforate): wide diameter, efficient, competitive in mild climates due to efficient conduction
CONIFEROUS
- trachea’s (imperforate): narrow diameter, safe, competitive in seasonally dry environments due to ‘safety’ features

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7
Q

comparison of the deciduous vs. the evergreen, coniferous habit – photosynthetic rates

A

DECIDIOUS
- deciduous 15-35 mg CO2 dm-2h-1
-evergreen 15-18 mg CO2 dm-2h-1
-freezing results in cavitation
CONIFEROUS
- 5-18 mg CO2 dm-2h-1
-photosynthesis at temperature below freezing

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8
Q

temperate and boreal forests - adaptations to freezing low temps

A

plants cannot tolerate intracellular ice formation
- intracellular ice-crystal formation is avoided by:
(1) supercooling
(2) extracellular freezing

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9
Q

temperate and boreal forests - supercooling

A

-mestastable
- small cells
- low nucleation
- accumulation of solutes
- limit of -40 C
- wind –> ice

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10
Q

temperate and boreal forests - extracellular freezing

A
  • plants decreasing in volume during freezing
  • water of cell walls more dilute than cells
  • as solvent extracted, depressed the freezing point
  • cells potentially die of dehydration
  • adaptations also at the membrane level (thawing expansion)
  • lollipops, excision, fluidity
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11
Q

temperate and boreal forests - low temps and tree distribution

A
  • trees species distribution is limited by low winter temperatures: both latitude and also elevation
  • ring porous species restricted to milder regions (and new growth each year)
  • diffuse porous species – not as limited, do not cavitate as easily in colder regions
    DICOTS
    a. constant size = diffuse porous
    b. steady dec. in size = semi-ring porous
    c. abrupt decrease in size = ring porous
    CONIFERS
    a. constant size
    b. cell wall thickness increases gradually
    c. cell wall thickness increases abruptly
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12
Q

temperate and boreal forests - treelines

A

at latitudinal extremes, conditions become too severe to support the growth of trees
- stress: physiological tissue damage due to low temperature or desiccation
- disturbance: mechanical damage due to wind abrasion, herbivory, snow loading, or fungi infection
- reproduction: reduced seedling and sapling establishment due to decreased pollination, seed development, seed dispersal, germination, or seedling establishment
- carbon balance: photosynthetic carbon gain minus respiratory demands is not enough to maintain minimum growth
- growth limitation: reduced development of new plant tissues due to low temps

the end of the tree-ed region may be abrupt, or represented by an ecotone of deformed trees: Krummholz

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13
Q

temperate and boreal forests- abrupt tree line

A
  • shade tolerat deciduous species
  • seedlings less tolerant of extremes than parents, establish under parents
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14
Q

temperate and boreal forests - krummholz tree line

A
  • deformed tree scrub, includes coniferous species
  • seedlings survive better than parents, but growth affected by environmental extremes resulting in Krummholz appearance
  • Krummholz may be genetically fixed (?)
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15
Q

temperate and boreal forests - phenological responses

A

phenology in temperate and coniferous forests is in response to light : PHOTOPERIOD
- Coniferous forests slow down with decreasing light and temperature: reproduce in spring
- deciduous forests show obvious phonological responses to temperature and light

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16
Q

phytochrome

A

deciduous forests
- pigment in plants that mediates response to photoperiod
blue –> phototropins and cryptochromes
red –> phytochrome
- discovered through germination response of light requiring seeds
- exposure to red light –> germinate, far red light inhibits germination
- conversion of Pr to Pfr by red light, results in physiological responses such as seed germination
- ratios of Pr:Pfr and darkness are important in determining amount of active phytochrome and thus responses

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17
Q

R:FR at different times of day

A

daylight – 1.19
sunset – 0.96
moonlight – 0.94

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18
Q

deciduous trees - color change

A

color change in response to decreased photoperiod
- chlorophyll is broken down enzymatically
- carotenoids are unmasked
- anthocyanin are synthesized (produced as a result of altered sugar metabolism due to phosphate decrease)
- amino acids are stored till spring

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19
Q

deciduous tree leaf abscission

A
  • reduce water loss, prevent damage from winter winds and snowfall, reduce insect predation
  • hormonally due to IAA and ethylene
  • development of an abscission zone seals off xylem, prevents further cavitation

leaf maintenance phase –> shedding induction phase –> shedding phases

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20
Q

deciduous tree reserves

A

accumulates starches (reserves for spring uses for new leaf flush) and sugars

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21
Q

deciduous tree bud break

A

occurs after a minimum cold period of one or more months followed by higher temperatures, 15 C to 20 C
- late flushing in oaks, etc., may ensure that transpirational demand remains low until new rings for conduction are formed

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22
Q

deciduous forests undestory

A
  • therophytes germinate in spring
  • stratification breaks dormancy of therophyes and cryptophytes
  • changing light conditions on the forest floor lead to shade tolerant species becoming dominant in summer
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23
Q

temperate and boreal forests - sun and shade leaves

A

microclimates in the understories and in the tree canopies differ significantly in light
- there are shade tolerant and intolerant species

sun leaves (compared to shade) :
- thicker
- more stomata
-more soluble protein (Rubisco)
- more deeply lobed
leaf dimorphism also in conifers

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24
Q

temperate and boreal forests - fire

A

temperate deciduous forests seldom burn
- coniferous forests burn frequently
fire type: surface (needles) and/or crown
frequency: surface 1 - 10 years, crown 100 - 1000 years
intensity: low for surface fires, high for crown fires

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25
Q

adaptation of conifers to fires

A
  • survive low intensity fires
  • killed bu high intensity fires
  • restistance correlated with
    -increased bark thickness
    • high open branching habit
    • lack of lichens
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26
Q

serotinous seeds

A

remain in the cone for up to 25 years
- resin bonds sealing cone scales melt at 60 C (in fire)
- seeds resist high temps
- released onto bare ground

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27
Q

fire and seed release

A

the third and perhaps most important agent of seed release is fire. hot air produced by locally intense fire and convected high into the canopy can dry cones, resulting in release of enormous quantities of seed over small areas. this increased seed fall coincides both spatially and temporally with fire related seedbed conditions favorable for seed germination and seedling survival.

first year giant sequoia seedlings established on treated-bulldozed or burned or both area, were 30 to 150 times more numbers than those on undisturbed forest floor

survival of sequoia seedlings for a 7 to 9 year period was 27% on areas subjected to a hot burn as opposed to 3.5% on other treated substrates

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28
Q

temperate deciduous forests - productivity and nutrient cycling

A

biomass/productivity - 120-300 t ha-1
seasonally very varied
nutrient cycling - major nutrients input from litter , quality of nutrient supply dependent on time of fall

decomposers - earthworms, nematodes, bacteria, fungi

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29
Q

coniferous forests - productivity and nutrient cycling

A

biomass/productivity - 10 - 160 t ha-1
site variable
nutrient cycling - infertile soils, nutrient limited, limited by rate of cycling, soil acid
evergreen, require less nutrients, lichen fall increasesN

decomposers - predominantly fungi

30
Q

tundra - geographic distribution

A

arctic, antarctic, sub-antarctic islands, and alpine tundra
- regions just below ice caps of the arctic, extending across N america, to europe, and siberia
- alaska and canada
- high latitude land masses (other places in the world) –> polar and alpine tundras are continuous

31
Q

tundra - species diversity and distribution

A
  • species diversity is low, <900 species flowering plants
  • gradients of decreasing diversity with increasing stress
  • species may be: widely distributed (circumpolar), disjunct (bipolar), and endemic (restricted to a mountain range)
32
Q

tundra - climate , polar

A

low temperature exerts the dominant effect
POLAR REGIONS
- ave temp <10 C for the warmest month
- above freezing < 2 months per year
- summers: high radiant energy input
- winters: negative radiant energy balance
- precipitation < 250 mm y-1, mostly snow
- permafrost limits the contribution of snowmelt

33
Q

tundra - climate, alpine

A

low temperature exerts the dominant effect
ALPINE REGIONS
- similar to polar regions at high latitude
- close the equator, diurnal (daily) temperature fluctuations become more important
- mountain rain shadow and fog affect the amount of available moisture
- snow insulates thus temperature is highest nearest the ground
- microclimate is important for growth of plants
- environmental gradients of topography, snow and wind influence plant distribution

34
Q

tundra - soils

A

cold and frost –> gleization, acid peats
–> rock shattering + rock sorting

permafrost vs. active layer –> thawed in summer in polar and daytime in alpine

low nutrients: acid, slow breakdown, leaching and lateral flow over permafrost

35
Q

tundra - growth forms

A

very little therophytes, mostly chameaphytes and hemicryptophytes
- growth forms show distributions within tundra biomes

36
Q

tundra, polar - adaptations for winter survival

A
  • low growth form: chameaphytes and hemicryptophytes, close to ground (cushion plants) increase heat uptake from ground
  • grasses insulated by dead leaves
  • rosettes insulated by living leaves
  • leaves are pubescent (hairy)
  • red coloration (anthocyanin- sugars) to increase leaf temperature
37
Q

tundra, polar - adaptations for reproduction during short cool summers

A
  • few annuals, summer too short for reproduction
  • semi-evergreen
  • vegetative reproduction
  • vivipary; the germination of seeds while still attached to the fruit, whether or not the fruit is still attached to the plant
  • initiate growth and flowering early before snowmelt: grow under snow (greenhouse effect) and flower through snow (cyanide resistant respiration)
  • flower over several seasons
  • high floral temperature (pollination and seed set) : heliotropism (the direcitional growth of a plant in response to sunlight) and furry flowers

sexual and clonal reproduction in flowers

38
Q

thermogenesis

A

thermogenetic plants have the ability to raise their temperature above that of the surrounding air –> heat is generated in the mitochondria as a secondary process of cellular respiration
- seen in skunk cabbage
- thermogenesis in plants is associated with cyanide resistant respiration aka alternative oxidation pathways (mitochondria produces heat, not ATP)

39
Q

tundra, alpine - adaptations to large daily fluctuations in temperature

A
  • giant rosette plants: convergent evolution –> giant rosette, cushion plants, sclerophyllous shrubs
  • night bud (nyctinastic leaves)
  • do not shed dead leaves
  • leaves have airspaces which increase insulation
  • pubescent (hairy)
  • thick roots resist frost heaving
  • andean-alpine : supercool
  • afro-alpine : extracellular ice formation
40
Q

tundra - productivity

A
  • very low : probably less than deserts, many limitations especially cold
    10 - 400
41
Q

tundra - nutrient cycling

A
  • slow: breakdown and weathering limited
  • nematodes, bacteria and fungi
  • animal manuring is a significant input
42
Q

tundra - disturbance/threats

A
  • very fragile biome –> carry capacity is easily exceeded (the number of living organisms and crops that a region can support without environmental degradation)
  • global warming is a big threat –> more carbon out than in, more thawed
43
Q

mangrove swamps (coastal wetlands) - geographic distribution

A
  • tropical and subtropical
  • sea surface temperature >24 C all year
  • influenced by ocean currents
44
Q

salt marshes (coastal wetlands) - geographic distribution

A
  • temperature and high latitude
  • sea surface temperature <30 C for most of year
  • predominantly N hemisphere
45
Q

coastal wetlands - factors required for development

A
  • coastal
  • occur where fine sediments accumulate
  • occur where wave action is minimal (usually associated with estuaries, also behind sand bars)
  • influenced by tidal action
  • freshwater input
46
Q

mangroves (coastal wetlands) - growth form and species diversity

A
  • dominant plants are woody trees (phanerophytes)
  • old world diversity high (over 40 species)
  • new world diversity low (8 species)
  • important groups are Rhizophore and Avicenna
  • unrelated species show convergent evolution
  • plants reproduce sexually
  • plants viviparous, allows for seedlings establishment on mud flats despite tidal action
  • colonization of new areas occurs through ‘propagule’ distribution by ocean currents
47
Q

salt marshes (coastal wetlands) - growth form and species diversity

A
  • dominant plants are grasses and low-growing succulent species (hemicryptophytes and chamaephytes)
  • grasses and succulents represent two different strategies for dealing with similar environmental stresses
  • diversity greater in temperate than high latitude areas
  • grasses are the most common species at high latitude
  • important groups include Puccinellia, Care, Juncus, Spartina, Distinchlis, Salicornia, Suaeda
  • in high latitudes plants reproduce vegetatively only, colonization of new areas occurs through ice-rafting of rhizomes
48
Q

coastal wetlands - zonation

A

plants show zonation in response to gradients established through tidal action
- gradients include:
anoxia, greater inundation, finer particles, wetter soil
substrate salinity, higher near the sea edge, lower near fresh water inflow, higher where evaporation between tidal extremes concentrates the salt
lights, highest on extending and back edge of mangrove swamps, low within the forest

extreme high tide= salt grass
mean high tide = pickle weed
mean seal level = cordgrass
mudflat

49
Q

coastal wetlands - adaptations to anoxia

A
  • anoxia = an absence of oxygen, caused by too much water/fooding, eliminates and replaces oxygen in the soil
  • rhizomes –> near surface, more chance of getting O2, stores starch to provide carbon which aids with the stress
  • pneumatophores –> an aerial root specialized for gaseous exchange
  • aerenchyma –> open channels for oxygen in roots, also helps with ethanol leaving the plants
50
Q

coastal wetlands - adaptations to salinity

A
  • salt exclusion at the root level
  • succulence –> dilution
  • semi-deciduous habit –>
  • salt excretion through salt glands –> quantitatively reduces salt stress, reduced imbalance of some ions (NA vs K)
  • accumulation of solutes –> overcoming water stress associated with salt stress , maintains transpiration
51
Q

coastal wetlands - productivity and nutrient cycling

A
  • high, similar to tropical forests
  • not nutrient limited
  • rapid degradation detritus, crabs (increase nutrients exchange through excretion
52
Q

coastal wetlands - disturbance/threats

A
  • loss of development: direct and indirect effects
  • sea level rise
  • land clearing for coastal development
  • erosion from agriculture and grazing
53
Q

river

A
  • fast moving current
    ORIGIN (headwater)
  • rainfall, snowmelt, ground water, lake outflow
  • four groups based on the ratio of discharge volume and drainage area
  • tropical rainforest
  • warm temperte or subtropical
    -moderately dry
  • desert rivers
54
Q

lake

A
  • standing body of water
    ORIGIN
  • tectonic , volcanic, glacial
  • other: man made, solution lakes, beaver lakes, etc
55
Q

lake temps

A
  • still water in lakes becomes thermally stratified
  • gives rise to thermal lake types
    -these occur at different altitudes and latitudes
  • affects water mixing and lake
  • dimictic: mix twice a year in spring and fall
  • monomictic: warm mix in winter, cold mix in summer
  • amictic: never mix always frozen
  • polymictic: mix everyday/weeks, shallow
    -oligomictic: rarely circulate
  • meromictic: so deep, have permanent thermoclines with seasonal thermoclines superimposed
56
Q

river temperatures

A
  • closely related to atmospheric temperatures
  • daily rhythms: afternoon maximum for small, clear streams
  • cooler at headwaters
  • turbulence reduces stratification
57
Q

rivers and lakes - light

A
  • absorption of radiant energy gives rise to thermal stratification
  • lakes divided into photic versus aphotic zones based on sufficient light for photosynthesis
  • light quality is affected by depth and lake nutrient type
    -green light predominates with increasing depth
58
Q

rivers and lakes - dissolved gases

A
  • O2 and CO2 important bc of photsynthesis
  • levels of O2 and CO2 are also influenced by photosynthesis
  • ratios of O2 and CO2 are different from the atmosphere
  • solubility of O2 decreases with increases temp
  • less oxygen dissolves into water at higher elevations bc of reduced atmospheric pressure
59
Q

dissolved gases - lakes

A
  • temperature is the most important determination of O2 and CO2 concentrations
  • oligotrophic lakes are near saturation for O2 and CO2
  • for eutrophication lakes, O2 concentrations are greater in the epilimnion because of photsynthesis; O2 in the hypolimnion is depleted during periods of stagnation, replenished by mixing
  • CO2 seldom limting in the long term, 30 times greater solubility than O2
  • CO2 can show dial variations
  • CO2 buffers pH
60
Q

dissolved gases - river

A
  • O2 and CO2 levels in natural rivers are near saturation, especially below fast flowing areas such as rapids
  • groundwater seeping into streams carries variable amounts of CO2 depending on the nature of the underlying rock
  • some species require such high O2, it only occurs near waterfalls
  • O2 levels fluctuate in response to ‘organic’ pollution, natural and man made
  • damming of rivers removed natural re-aeration
  • giant spillways result in supersaturation; e.g. columbia river where gas bubble disease kills salmon during migration
61
Q

rivers and lakes - nutrients

A
  • nutrient concentrations in lakes reflect mineral composition of incoming rivers and land use practice
    -soft water contains few dissolved solutes: igneous rock
  • hard water contains dissolved solutes: sedimentary rock
  • N and P most limiting, but increased where sewage, fertilizers,
62
Q

rivers and lakes - life forms

A

life forms depend on position within the lake or river
LAKES
- littoral: shallow water anchorage and light to the bottom
- pelagic: floating deep open water
- limnetic: light for photosynthesis
- profundal: light limited

submerged vegetation -> floating vegetation –> emergent vegetation –> riparian bushes –> riparian trees –> forest canopy trees

RIVERS
- differences in distribution along the length

63
Q

adaptations in aquatic plants - submerged angiosperms

A
  • reduced structural tissue, little lignin
  • no cambium
  • xylem cavities
  • leaves narrow and elongated
  • SA: mV high for increased uptake
  • heterophylly
  • rhizomes/stolons
64
Q

adaptations in aquatic plants - floating-leaved

A
  • restricted to sheltered sites
  • rhizomes anchor
  • long flexible petioles, allow for wave action
  • aerenchyma, floating
  • stiffened veins
  • stomata on upper surface, raised
  • hydrophobic leaf surface
65
Q

adaptations in aquatic plants - free floating

A
  • more variable
  • flotation mechanism, e.g., water repellent hairs, his trap air bubbles, have gas bladders
  • WEEDS
66
Q

adaptations in aquatic plants - morphological

A
  • angiosperms are secondarily aquatic, i.e. returned to water
  • have cuticles, stomata, and features associated with the terrestrial environment
67
Q

adaptations in aquatic plants - physiological

A

adaptations to low O2 conditions (anoxia)
- aerenchyma allows diffusion of toxic in products of respiration to the surface
- rhizomes store carbohydrates

68
Q

adaptations in aquatic plants - photosynthesis

A

-CAM photosynthesis associated with low daytime CO2
- most species C3 and shaded adapted
- some C4

69
Q

rivers and lakes - productivity and nutrient cycling

A

-plants and phytoplankton contribute to primary productivity
- primary productivity is very low
- lower than most terrestrial ecosystems, higher than the ocean
- limited by nutrients, also sometimes light
- seasonal effects through temperature, nutrients, oxygen depletion

70
Q

rivers and lakes - human impact

A

POLLUTION
- low nutrients and nutrient limitations make lakes and rivers susceptible to eutrophication (excessive richness of nutrients due to runoff from the land that causes a dense growth of plant life and death of animal life from lack of oxygen)
RESERVOIR CONSTRUCTION
- removal and channel modification

world vegetation (4 decks)

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