Frst 211

Front 1

Resources - Plant needs

Back 1

1) sunlight in visible band
2) CO2 (from atmosphere)
3) H20 (from soil)
4) nutrients (macro/micro)
5) space to acquire resources

Front 2

Resources - Animal needs

Back 2

1) O2 (from atmosphere)
2) H2O (from environment)
3) nutrients/E sources (varies depending on habitat and type of animal - herbivore etc)
4) space to acquire resources (habitat)

Front 3

Resources

Back 3

-all things consumed by an organism
-consumption causes a decrease in supply of resource (less is available) - can become critically limiting
*absence of any of the resources that plants/animals need is limiting to life

Front 4

Environmental factors

Back 4

-abiotic environmental factors that influence organisms but are not consumed
1) climatic
2) topographic
3) edaphic

Front 5

Environmental factors - climatic

Back 5

a) Temp and PPT (including snowpack duration)
-directly influences rate of physiological processes (organism itself)
-metabolic processes have a certain temp range
-indirectly influences the availability of/demand on resources

b) wind
-affects vegetation in exposed locations

*potential midterm Q: explain and interpret the different vegetation on slopes on either side of a mountain - with the environmental factors

Front 6

Environmental factors - topographic

Back 6

=landforms
-slope aspect = orientation of the slope
(S>W>E>N)
-elevation = location relative to sea level
-slope position = location relative to local mountain peaks and valleys
-slope steepness = angle relative to horizontal

-topography influences incoming solar radiation, microclimate, and sol water balance

Front 7

Environmental factors - edaphic

Back 7

=soil
-texture, structure, organic matter, organisms, acidity & nutrient availability

Front 8

theory of tolerance

Back 8

each and every species is able to exist and reproduce successfully only within a definite range of values for a particular environmental factor
*note: there are both upper and lower limits of tolerance, beyond which the organism dies
*can look at/graph one environmental factor at a time, or combine them

Front 9

Climatic envelopes

Back 9

-climate factors interacting to determine the distributional limit of a species
-includes: moisture, annual minimum temp, arid vs. humid climates, annual snowfall,

*competition line happens where the species is at a competitive disadvantage because of this conditions

Front 10

ecological niche

Back 10

-a characteristic of a species that is defined by considering the species combined tolerance ranges for all of the environmental factors that influence it
-each factor can be considered as one niche dimension
-multidimensional - as many dimensions as factors that define the niche
-includes biotic interactions b/c species in the same niches will interact

Front 11

negative biotic interactions

Back 11

cost to one or both species
-competition -, -
-predation +, -
-herbivory +, -
-parasitism +, -

Front 12

positive biotic interactions

Back 12

benefit one or both species
-commensalism +, o
-mutualism +, +

Front 13

neutral biotic interactions

Back 13

no effect on either species

Front 14

physiological amplitude

Back 14

-relates to range of tolerance (alternate representation)
-optimal growing conditions without competition
ie/ most trees grow best in fresh, rich soil

Front 15

ecological amplitude

Back 15

distribution depends on competitive influence of neighbouring plants

Front 16

niche

Back 16

-characteristic of a species "profession"
-potential distribution of the species

Front 17

habitat

Back 17

-the actual place where the organism lives "address"
-characterized by a particular set of environmental factors that match the organisms niche

Front 18

biomes

Back 18

-largest division of terrestrial ecosystems, subdivided into formations
-regional-scale ecosystems, strongly related to climate and soils
-described by the physiognomy of the dominant vegetation

Front 19

physiognomy of biome

Back 19

architecture and life-forms of the vegetation

Front 20

architecture of vegetation

Back 20

-look at structure
-ID canopy layers or strata
-qualitative or quantitative measures

emergents, canopy, subcanopy, shrub layer, ground cover

Front 21

emergents

Back 21

scattered trees, above main canopy layer

Front 22

canopy

Back 22

crowns of the trees mostly exposed to sun

Front 23

subcanopy

Back 23

trees with crowns mostly shaded

Front 24

shrub layer

Back 24

shrubs, large herbs, seedlings, saplings
-2-3m in height

Front 25

ground cover

Back 25

moss, herbs, ferns, bare ground

Front 26

life forms of vegetation

Back 26

attributes to describe vegetation
ie:
growth form - graminoid, herb, shrub, tree, vine
size - seedling, sapling, tree
lifespan - annual, biannual, perennial
tissue - herbaceous, woody
leaf traits - needle/broadleaf, evergreen/deciduous

Front 27

biomes and formations

Back 27

-five biomes and six forest formations
-strongly related to climate

Front 28

tundra

Back 28

treeless, vegetation compact to the ground

Front 29

desert

Back 29

tree-like growth forms, succulents, shrubs/herbs, bare ground

Front 30

grasslands

Back 30

graminoids, broadleaf forbs/herbs, perennials, low to ground canopy dominates, below ground biomass, trees in riparian areas

Front 31

savannahs

Back 31

grass dominated understory, scattered emergents

Front 32

Forest

Back 32

high variability
-tropical rainforest
-monsoon forest
-subtropical evergreen
-midlatitude deciduous
-sclerophyll
-needle leaf

Front 33

ecosystem determinants

Back 33

factors that determine ecosystem characteristics

Front 34

vegetation characteristics

Back 34

= CL + O + R + P + T
CL = climate (energy and water = water balance)
O = organisms (litter + bacteria > nutrients)
R = topographic relief (elevation, slope, aspect)
P = parent material or geological substrate that is the basis of soil
T = time since disturbance

Front 35

CLORPT also relates to vegetation characteristics

Back 35

CL = climate and soil = factors responsible for general similarities in vegetation at sub-continental or regional scales
=biomes and formation classes

ORPT = local scale factors which cause variation between sites
=niches and habitats

Front 36

weather

climate

Back 36

=conditions of the atmosphere at a given place and time

=long-term weather averages, variability and extremes

Front 37

General atmospheric circulation model
-basic principles

Back 37

1) warm air rises and cold air sinks
2) warm air - low pressure, high moisture capacity, converging, ascending
3) cold air - high pressure, low moisture capacity, diverging, descending
4) air flows from high to low pressure
5) coriolis deflects to the right in the N hemisphere, to the left in the S hemisphere

Front 38

General atmospheric circulation model
-primary low- and high- pressure areas

Back 38

1) equatorial low-pressure trough
-@equator, high temp = low pressure trough
-warm, wet air converges and rises producing clouds and rain
2) subtropical high-pressure cells
- 20-30 degrees N/S latitude, high pressure zone, hot, dry air
3) subpolar low pressure cells
-60 degrees N/S latitude, low pressure zone, cool, wet air
4) polar high-pressure cells
-poles, low temp = high pressure cells
-cold, dense air, descends & diverges

Front 39

General atmospheric circulation model
-Hadley cells and trade winds

Back 39

-air source = equatorial low pressure has converging, ascending air
-rising air moves toward the poles on upper atmosphere winds then descend in the subtropics at about 20-30 degree N/S latitude
-descending air = high pressure
-surface flow is from high pressure to low pressure
-surface flow + coriolis effect = trade winds (NE in S.hemisphere and SE in N.hemisphere), converge @ equator creating the ITCZ
-entire system = "Hadley cells"

Front 40

General atmospheric circulation model
-Midlatitudes and Polar front

Back 40

-at 60 degrees latitude = low pressure belt
-winds from polar H to subpolar L = polar easterlies
-winds from subtropical H to subpolar L = westerlies
-polar front = meeting of cold air from N and warm air from S in the midlatitudes makes midlatitude cyclonic storms centred on low pressure
-polar jet stream = westerly flowing air above the polar front, positioned in the tropopause

Front 41

Köppen-geiger climate classification system

Back 41

-five climate groups based on average monthly temp and PPT and total annual PPT
-groups are subdivided into types, depending on seasonality, temp, PPT
-boundaries based on climate data and vegetation

Front 42

Köppen-geiger climate classification system
-climate groups

Back 42

A - tropical rainy climates, equatorial tropical regions below 25 degrees latitude
B - dry climates, where evapotranspiration > PPT
C - mesothermal, mild, 25-60 degrees mid-latitude, distinct seasons, some maritime
D - microthermal, severe mid-latitidues, >25 degrees latitude, continental
E - polar, boundary corresponds to arctic/antarctic treeline, tundra, ice caps

A, C, D, E = humid climates where PPT>evapotranspiration

H - highland climates, variable over short distances, types not mapped at global scale

Front 43

soil water balance

Back 43

P = E + (delta S) + R
-for a specific place and time, balance of water and outputs

inputs = PPT (P)
outputs = E + (delta S) + R
E = evapotranspiration
delta S = change in storage (+G = recharge, -G = utilization)
R = runoff of surplus (surface and ground water)

Front 44

soil water recharge (+G)

Back 44

-fills available pore spaces in soil
a) capillary water - water that resists gravity by clinging to soil particles via capillary tension (effected by soil/porosity)
b) storage capacity - amount of capillary water available for plant use

Front 45

soil water utilization (-G)

Back 45

evapotranspiration = rate of water vapour return to atmosphere from the ground (evaporation) or plant cover (transpiration)

Front 46

Potential evapotranspiration (PE)

Back 46

= ideal rate that would occur if complete plant cover and unlimited water
-measures water need
-represents energy availability (b/c it becomes the limiting resource)

Front 47

actual evapotranspiration (AE)

Back 47

= rate that actually occurs given availability of biological usable energy and water
-measures water use
-represents water availability

Front 48

deficit (D)

Back 48

-PE >= AE
-Deficit = PE - AE

Front 49

Midlatitude broadleaf forest of ontario

Back 49

growth form:
-broadleaf
-divergent branches @ top (spreading, wide crown) = access to light & increased transpiration rates

climate:
-humid summers
-cold, snowy winters
-more temp extremes (continental effect)

limitations & adaptations:
-abundant water in summer
-E-limited forest
-winter deciduous = snow loads & drought protection

Front 50

coastal temperate rainforest of BC

Back 50

growth form:
-needleleaf
-divergent branches @ base (longer @ base, conical tree form) = access to light

climate:
-summer drought
-mild, wet winters, maritime effect

limitations & adaptations:
-water limited forests
-summer drought
-evergreen, chemical & physical drought adaptations

Front 51

classification

Back 51

forests in canada are classified according to ecozones and forest regions. Together these classifications provide a science-based foundation for forest management decision-making at the national level

Front 52

Ecozone

Back 52

an area of the Earths surface representing large and very generalized ecological units characterized by interacting abiotic and biotic factors

Front 53

ecozone classification

Back 53

-distinguished by unique geology, climate, vegetation, wildlife and human factors
-subdivided into ecozones and ecoprovinces
-hierarchical units are useful for reporting/planning at national, provincial and regional levels

Front 54

How many ecozones does Canada have?

Back 54

-15 terrestrial, subdivided into 53 ecoprovinces, which subdivided into 194 ecoregions
-5 marine

Front 55

Canadian terrestrial ecozones

Back 55

-12 terrestrial ecozones are at least partly forested: Hudson Plains, Taiga Plains, Taiga Shield, Boreal Shield, Atlantic Maritime, Mixedwood Plains, Boreal Plains, Prairies, Taiga Cordillera, Boreal Cordillera, Pacific Maritime, Montane Cordillera
-3 arctic ecozones are not forested: Arctic Cordillera, Northern Arctic, Southern Arctic

Front 56

ecozones determinants

Back 56

1) temp
2) PPT
3) Geology & Soils

Front 57

ecozones determinants - temperature

Back 57

-N-S gradients are determined by solar inputs (day lengths and sun angles)
-location relative to Pacific, Atlantic and Arctic Oceans determines continentality

Front 58

ecozones determinants - PPT

Back 58

-warm, wet air masses from the Pacific Ocean move W to E on the prevailing westerlies
-cold, dry air masses from the Arctic collide with the warm, wet air masses from the Gulf of Mexico along the polar front, strongly influencing the eastern and central parts of Canada

Front 59

ecozones determinants - Geology & Soils

Back 59

-Canadian shield (position/influence), ancient igneous granitic rock, underlies half of Canada's land mass
-3 major mountain ranges are the Arctic Cordillera (NE), Coastal and Rocky mountain ranges (W cordillera, continental divide) and strongly influence regional climate and soils (adiabatic PPT/rain shadows)

Front 60

Arctic Cordillera (AC)
Northern Arctic (NC)
Southern Arctic (AC)

Back 60

Northern most ecozones
-high latitude, low solar E (b/c of solar angle, even with long days) & PPT inputs;
- permafrost limits soil water availability to plants (Arctic desert wetland paradox); non-forested tundra

Front 61

Arctic desert wetland paradox

Back 61

-low PPT, but humid, permafrost prevents percolation, abundant standing surface water but low water availability

Front 62

Boreal Shield (BS)
Taiga Shield (TS)
Hudson Plains (HP)

Back 62

-canadian shield, still undergoing isostatic rebound
-soils deeper to the south and shallower to the north with exposed rock and discontinuous permafrost;
-lowlands south of Hudson and James Bay are poorly drained wetlands and bogs

Front 63

Atlantic Maritime (AM)
Mixedwood Plains (MP)

Back 63

-SE of canadian shield
-densely populated and highly altered by humans over 400 yrs
-broadleaf
-MP: great lakes-St Laurence + Carolinian forests
-AM: Acadian forests

Front 64

Prairies (P)
Boreal Plains (BP)
Taiga Plains (TP)

Back 64

-grasslands/boreal forest
-rainshadow of W cordillera
-glaciation influenced by topography, soils & wetlands/lakes
-grasslands transition to parkland to forest fromS to N
-highly altered by humans in the S

Front 65

Pacific Maritime (PM)
Montane Cordillera (MC)
Boreal Cordillera (BC)
Taiga Cordillera (TC)

Back 65

-Western cordillera
-strong latitudinal gradient in temperature
-W-E and low-high elevation PPT gradients
-diverse topography strongly influences vegetation and human impacts

Front 66

forest region

Back 66

a geographic zone with fairly uniform vegetation cover in terms of dominant species and stand types
-based on vegetation or forest composition not on environmental variables

Front 67

forest regions of canada

Back 67

Boreal
Acadian
Great Lakes - St Lawrence
Carolinian (Deciduous)
Coast
Columbia
Montane
Subalpine

Front 68

Boreal forest region

Back 68

location (ecozones)
-northern Canada (MP, BS, TS, HP, BP, TP, BC, TC)

dominant tree species
-white spruce, black spruce, balsam fir, jack pine, white birch, trembling aspen, tamarack, willow

Front 69

Acadian forest region

Back 69

location (ecozones)
-maritimes (AM)

dominant tree species
-red spruce, balsam fir, yellow birch

Front 70

Great Lakes-St. Lawrence forest region

Back 70

location (ecozones)
-central Canada (MP, BS)

dominant tree species
-red pine, eastern white pine, eastern hemlock, yellow birch, maple, oak

Front 71

Corolinian (Deciduous) forest region

Back 71

location (ecozones)
-SW Ontario (MP)

dominant tree species
-beech, maple, black walnut, hickory, oak

Front 72

Coast forest region

Back 72

location (ecozones)
-BC (PM)

dominant tree species
-W red cedar, W hemlock, sitka spruce, DF

Front 73

Columbia forest region

Back 73

location (ecozones)
-BC (MC)

dominant tree species
-W red cedar, W hemlock, DF

Front 74

Montane forest region

Back 74

location (ecozones)
-BC & Alberta (MC)

dominant tree species
-DF, lodgepole pine, ponderosa pine, trembling aspen

Front 75

Subalpine forest region

Back 75

location (ecozones)
-BC & Alberta (MC)

dominant tree species
-Engelmann spruce, subalpine fir, lodgepole pine

Front 76

Forest regions in BC

Back 76

5 of the 8 Canadian forest regions are found within BC
(+ alpine tundra & grasslands)

b/c:
-moderating influence of the pacific ocean + the westerlies
-mountainous terrain (topography)
-latitudinal variation

Front 77

National Forest Inventory (NFI)

Back 77

a collaborative effort between the federal, provincial and territorial governments, compiles detailed information for each of Canada's 12 forested ecozones
-network of permanent observational units located on a national grid covering 1% of Canada's landmass
-combination of ground plot, photo plot and remote sensing data
-data on dominant species, volume of wood and remote sensing data
-ongoing monitoring provides accurate, timely, and consistent information on the state of sustainable management of Canada's forests

Front 78

climate regions of BC

Back 78

-Pacific: along coast
-Cordilleran: S/N mtn ranges
-Boreal: NE BC
-oriented N-S
-mountain ranges strongly influence temp + PPT regimes

Front 79

coarse scale influences on BC climate

Back 79

Global circulation model
-aleutian low b/c of low pressure @ 60 degrees N
-high pressure @ 30 & 90 degrees N, along Cali/Oregon coast & arctic
-westerlies = prevailing winds
-polar easterlies

Regional Air Masses
-maritime polar
-continental polar
-continental arctic

Front 80

Temperature & BC Climate

Back 80

1) latitude
-influences sun angle, day length and seasonality

2) Longitude: Continentality and Cloud Cover
-land vs water
-in BC W-to-E gradient

3) Topography
-aspect = orientation relative to the sun
-elevation = temp decreases with increased elevation

Front 81

Environmental Lapse Rate

Back 81

= change in temp with altitude (for stable, unmoving air)
-average ELR = 6.4 degrees per 1000m
-varies with local weather conditions

Front 82

Dry Adiabatic Lapse Rate (DALR)

Back 82

= rate of temp change with altitude for a parcel of moving air that is not saturated (RH < 100%)

=10 degrees per 1000m

Front 83

Adiabatic cooling

Back 83

-as an air mass ascends there is less pressure affecting it and it expands
-with expansion sensible heat is used and it cools although no heat energy is lost or gained by the surrounding environment

Front 84

Adiabatic warming

Back 84

-opposite to cooling
-as an air mass descends it compresses and warms

*note: for moving air, the temp change depends on whether the air is dry or saturated

Front 85

Moist adiabatic lapse rate (MALR)

Back 85

= rate of temp change depends on whether the air is dry or saturated (RH = 100%)
=6 degrees per 1000m

MALR is less than DALR because latent heat of condensation is liberated into the air mass as sensible heat so the rate of cooling is lower

Front 86

PPT & BC climate

Back 86

1) types of uplift leading to PPT

2) snow

Front 87

convergent uplift

Back 87

-low pressure
-influence of the Aleutian low (+ subtropical high)
-low = convergent flow
-westerlies carry air masses onshore + orographic uplift = ppt
-high = blocks or diverges westerlies = dry conditions
-summer = weaker L + northward shift of H + westerlies leads to seasonality:
vancouver - summer dry
prince rupert - always wet

Front 88

convectional uplift

Back 88

-associated with continentality
-surface heating of land: uplift of warm air masses, turbulence + cumulonimbus clouds, thunderstorms
-interior BC, continental warm summers
-results in summer-wet PPT regime

Front 89

frontal systems

Back 89

-air masses
-"front" = zone of contact of two air masses
-name = "aggressive" air mass
-affects all parts of BC

ie/ cold front in Northern BC:
-polar easterlies(continental, polar air mass) + westerlies (maritime, polar air mass) = PPT

Front 90

snow

Back 90

a) snowpack - maximum at high altitude and latitude: W>E
b) accumulation and feedbacks
high albedo
=high reflection
=low absorption of polar E
=cool temps
=PPT as snow
=persistent snow pack
=high albedo
*snow accumulates and persists where it already exists

Front 91

traditional successional paradigm

Back 91

-communities well integrated units with populations that are co-evolved and tightly bound
-component species are interdependent, highly integrated, required to function
-species in an association have similar distributions, which are predictable in space and time
communities boundaries are distinct and persistent, ecozones are narrow
-succession is highly ordered, predictable process, deterministic
-physical site and biotic resources are constant over time required for succession
-compositional change = relay floristics
-stable, equilibrium (absence of disturbance)
-different sites converge to common climax driven by regional climate

Front 92

relay floristics

Back 92

each seral stage facilitates the next to climax
-disturbance yields site
-few species invade and dominate the site
-alter microenvironment of the site making it more suitable to other species
-new species invade, dominate, and further modify the site for next group of species (facilitation)
-succession ends when a group of species able to replace itself become dominant = climax community

Front 93

traditional paradigm & 20th century management and conservation

Back 93

if
...ecosystems are discrete with clear boundaries
...climax ecosystems are stable and in equilibrium with the environment
...disturbances are rare, but disturbed ecosystems return to equilibrium in a predictable way

then
...knowledge of site and vegetation predict future
...disturbed forests (clear cuts) will recover and
...maintain site quality + vegetation potential = sustainable

then
...any unit of nature = adequate for conservation
...protected ecosystems maintain themselves "in balance" in their initial, desirable state

Front 94

problems with climax concept

Back 94

-most communities are dynamic and changing in responses to environmental variation
-disturbance is common and change is ubiquitous
-climax is rare, disturbances of range of types and magnitudes is the norm

Front 95

Contemporary successional paradigm

Back 95

(post 1970s)
-species are individuals with gradual changes in abundance and distribution
-species in a community coexist because they have overlapping environmental needs and tolerances
-current communities = temporary assemblages of populations, with an element of chance (can function with the removal/addition of some species)
-communities are complex and variable in space and time

Front 96

succession in contemporary paradigm

Back 96

complex and variable due to environmental variation and stochastic change
initial floristics + multiple disturbances = complex forest dynamics

Front 97

initial floristics

Back 97

-after a major disturbance, most species colonize the site immediately after, rather than invading through time
-dominance changes trough time
-different species dominate through time due to differences in life history attributes: seed abundance and size, mechanism of dispersal, initial growth rates, lifespan and maximum size, competitive abilities, tolerance of shade, etc

dominance = f(life history)

Front 98

initial floristics + multiple disturbances

Back 98

-subsequent disturbances of a range of types and magnitudes alter site conditions and increase heterogeneity
-allow regeneration of early successional species, increases in abundance of existing species, establishment of new species
-size and timing of the disturbances increases complexity and successional trajectories and result in multiple successional pathways

Front 99

implications of the contemporary paradigm for forest management and conservation

Back 99

alternate approach to forest management and conservation that emerged in response to the contemporary view of succession: "ecosystems management based on historic range of variation

Front 100

key objectives of contemporary paradigm

Back 100

-maintain ecosystem resistance to and recovery from disturbance
-maintain adaptability to long-term changes in environmental conditions

Front 101

emerging paradigm

Back 101

managing ecosystem resilience given uncertainty (due to global change)

Front 102

traditional paradigm summary

Back 102

-predictable
-deterministic
-equilibrium (focus on climate & soils)
-managed to conserve stable states (end point)
-stand level decisions
-homogenized landscapes (not as much variation as there used to be)

Front 103

contemporary paradigm summary

Back 103

-complexity
-multiple pathways
-non-equilibrium (focus on disturbances & variation)
-managed to maintain processes (disturbances, biotic interactions, etc)
-multi-scale management
-increasing heterogeneity

*interpretation has shifted, but the BEC system hasn't caught up yet which is a major constraint

Front 104

climate variability (variation)

Back 104

-interannual to decadal variation in climate
-variation around long term trend
-short term (years), rises and falls about the trend line

Front 105

climate change

Back 105

-multidecadal to century long directional trend
-long-term climate change above and beyond natural climate variability
-change longer than reference period of 30 yrs

Front 106

reference period

Back 106

~30-40 yrs
encompasses natural cycles of cooling/warming ue to ocean currents

Front 107

proxy-climate record types

Back 107

-ice cores
-tree rings
-corals
-lake and ocean sediments

Front 108

Ice core proxy-climate

Back 108

-analysis of ice cores from glaciers and ice sheets
-annual snow accumulation forms compressed layers of ice with air bubbles
-annual layers of ice are dated to provide chronological time sequence
-geochemical analysis of air bubbles
-comparison of successive layers indicate changes in atmospheric composition
-O2 isotopes indicate temp
-CO2 concentration is measured in ppm
-temporal trends in ice core record: saw tooth pattern indicating gradual cooling trend then abrupt change to warm conditions
-long glacials and short interglacials, primarily driven by Earths orbital geometry (from circular to elliptical on ~100, 000 yr cycle)

Front 109

earths orbit impact on paleo-climate

Back 109

circular = regular solar input to earth, warmer
elliptical = variable solar input, overall cooler

Front 110

other factors explaining paleo-climate cycles

Back 110

-ice-climate feedbacks
-climate-carbon feedbacks
-ocean-atmosphere interactions

Front 111

ice-climate feedbacks

Back 111

ice builds up slowly but can melt quickly with feedbacks to climate to accelerate warming once melting starts

Front 112

climate-carbon feedbacks

Back 112

warmer temps = greater biotic activity and greater oceanic mixing and produce more C, which results in more greenhouse warming

Front 113

ocean-atmosphere interactions

Back 113

ocean currents transport tropical energy to high latitudes but switch off during glaciation, reducing energy at high latitudes, facilitating ice sheet development

Front 114

Corals proxy-records

Back 114

-analysis of annual bands to determine coral age, density, stable isotope and element ratios
-continuous records over past 400yrs, fossil corals = 1,000s of yrs
-indicate environmental conditions in shallow and near-shore tropical oceans

Front 115

tree rings proxy-records

Back 115

-analysis of annual bands to determine tree age, ring-widths, density, isotope and element ratios
-continuous records over past 11,000yrs possible by cross-dating of samples from live and dead trees
-indicate environmental conditions in temperate and boreal forests
-climate is important factor in influencing tree growth

Front 116

Rt = At + Ct + δD1t + δD2t + Et

Back 116

where:
R = ring width in year t
A = age related growth trend due to normal physiological aging processes
C = climate that occurred during that year
D1 & D2 = disturbance factors causing change in growth rate, ie/ insect defoliation or fire
E = random processes not accounted for by these other processes (error)

Front 117

Global climate variation and change

Back 117

-Earth's climate is always varying at a range of temporal scales
-temperature reconstruction for N hemisphere using multiple proxies over 2000 yrs shows: gradual cooling form 1000-1800AD, on average: cooler temps than 1961-1990s
-instrumental record for 20th century show warmest temps and rapid rate of change

Front 118

evidence linking human activities to global warming

Back 118

can use hind-casting models that fit last 150 yr trend to predict what may happen, says that natural + anthropogenic sources have contributed thus far ( vs natural or anthropogenic alone)

Front 119

Köppen-Geiger climate classification

Back 119

-based on changes in climate measured around the world, the spatial boundaries for climate groups and types are changing, esp at high latitudes and in the driest climates (B climate group)

Front 120

projected future climate trends in BC

Back 120

-changes to BC climate will exceed the global average given our high latitude

Front 121

summary of predicted temp changes in BC

Back 121

-on average, mean annual temp (MAT) will increase by 3-5 degrees by 2100
-both summer and winter temps will warm; winters will warm faster and more than summers
-warming will be greater in N than S
-least amount of warming expected in coastal areas where temp is moderated by the ocean temp

Front 122

summary of predicted ppt changes in BC

Back 122

-on average, mean annual ppt (MAP) will increase 0-5% but changes in MAP are variable among regions and seasons
-overall, central & S BC will get drier, N & coastal BC will get wetter
-summer ppt in S BC will decrease by 10-15%, N BC will be wetter by ~5%
-winter ppt will increase 10-20%, greatest changes along S coast and N BC

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regional climate & BEC zones

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-within each BEC zone in BC regional climate (macroclimate) is considered the primary determinant in soil formation processes and late-successional tree-species composition
-using instrumental climate records and spatial modelling of climate and zone distribution boundaries, the contemporary climate envelope or signature associated with each BEC zone was derived
-verifies that climate envelopes are a good representation of current conditions within the zones

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flying BEC zones

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-projected climate envelope of BEC zones
-do NOT indicate the future distribution of BEC zones
-climate associated with BEC zones, not vegetation types associated with that zone, in order for the zone to move all the tree species must have essentially same silvics (seed abundance, dispersal, germination, survival, growth rates, mortality rates, lifespan etc)
-contemporary ecological paradigm indicates that species respond to change individualistically, therefore unlikely that zone vegetation will move as a unit

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individualistic species responses

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-using instrumental climate records and spatial modelling of climate and current tree distribution boundaries, the contemporary climate envelope has been derived
-these combined with projected climate from models = projected climate envelope of individual species

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direct effects of climate change on trees

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altered rates of:
- tree survival/mortality
-growth
-regeneration success
*these interact to determine species distributions

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indirect effects of climate change on trees

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-climate-mediated disturbances such as fire, insects, pathogens and their interactions
-essential components of forest dynamics
-potential catalyst facilitating changes in species distributions and community composition

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No-analogues (based on paleoecological records)

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-future climate conditions and communities may differ from current or past conditions
-given changing climate and differences in migration rates among species
-species may co-occur in future although their ranges do not overlap at present, new combos are likely in future

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Four stage stand development

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1. stand initiation
2. stem exclusion
3. understory re-initiation
4. old-growth

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stand initiation

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-after a severe, stand replacing disturbance, the site is "open"
-new individuals and species colonize the site until it is fully occupied, which may take several years to decades, depending on environmental conditions
-duration varies with site, size, and severity of disturbance, source of propagules, life history attributes of colonizing species, interactions among species, stochasticity

1) colonization & establishment
2) allocation to growth - competitive advantage
3) environmental factors become limiting

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stem exclusion

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-growing space occupied, crown closure
-no new establishment
-resources become limiting (canopy closure, foliage layer rises)
-intense competition (self-thinning, crowding-dependent mortality, exclusion of less fit species)

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self thinning

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natural thinning, death from suppression

-results in a size hierarchy with different heights and diameters among species/individuals; different canopy strata and/or crown classes within strata
-in mixed species stands, where species have different maximum sizes, growth rates and tolerance of shade, differences in height classes can be pronounced and results in stratified mixed species stand

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self thinning rule

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trajectory of a single population in a single location through time under conditions where density-dependent mortality occurs

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B = CN ^ (-1/2)

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where:
B = biomass per unit area
C = constant
N = number of individuals per unit area
-equation discribes the boundary line toward which plant populations grow

-below line, biomass +/or numbers of individuals increase until they reach line and self-thinning begins
-above the line, mortality reduces density towards line
-along the line, individuals die at a rate related to the rate of biomass accumulation

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understory re-initiation

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-overstory trees stratify, crowns change shape and individuals die creating openings, releasing growing space and other limiting resources
-propagules may be from persistent seed bank, seeds from canopy trees or dispersed from other stands
-herbs, shrubs and tree regeneration establish and survive in the understory (growth may be limited)
-seedling banks of slow-growing, shade-tolerant, advance regeneration may develop

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old-growth stage

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-gap-phase dynamics
-death due to senescence of fine scale disturbance including pathogens, insect and wind
-can be transition or true old growth
-specific stand structures are associated with old-growth forests: large, living, old trees; large standing dead trees; large fallen logs; canopy with multiple strata and trees of a range of size/age classes; diverse understory composition

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gap-phase dynamics

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-one to several overstory trees die, creating gaps in the canopy
-increases resource availability to understory trees, allowing them to grow and recruit into the overstory

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transition old-growth

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stands include part of the initial post-disturbance cohort

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true old-growth

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stands comprised entirely of trees that established beneath an existing forest canopy

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limitations to 4-stage model

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although widely, successfully applied to many temperate, closed-canopy forests, it does not adequately explain the structure and dynamics of old-growth forests because:
1) need initial disturbance to be severe, leaving no legacy
2) interpretation of forest succession has focused on living trees and the early stages of development following catastrophic disturbance
3) emphasis on the early stages of forest development is consistent with the objective of sustained timber yield (SI + SE + UR = 80 - 100yrs = 10% of lifespan of many trees)

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8-stage model of stand development
-additional considerations

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-severity of initial disturbance
-deadwood and structural legacies
-spatial variation
-complexities and variation in late stages of development

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8-stage model of stand development

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1) disturbances and legacy creation
2) cohort establishment
3) canopy closure
4) biomass accumulation/competitive exclusion
5) maturation
6) vertical diversification
7) horizontal diversification
8) pioneer cohort loss

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Disturbance and legacy creation

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-biological legacies = living and dead structures that persist after natural disturbance
-variation in disturbance provides a range of starting points

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cohort establishment

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can include new propagules to the site or release of surviving advance regeneration

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canopy closure

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-trees re-establish dominance of site
-trees grow until individual canopies overlap, closing the canopy and affecting the understory

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biomass accumulation/competitive exclusion

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-biomass accumulation may proceed without self thinning when stand densities are low
-trees competitively exclude other plants
-lower tree branches are pruned and crown classes differentiate

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maturation

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-pioneer cohort of trees reach maximum height and crown spread
-overstory trees develop "decadent" features (broken and multiple tops) and fine-scale disturbance replaces self-thinning as cause of mortality
-in the understory coarse woody debris is minimal but understory plants begin to establish, including shade-tolerant tree regeneration

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vertical diversification

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-canopy continues to open through crown dieback and tree mortality, adding structural complexity and creating niches
-shade-tolerant regen and lower canopy trees recruit to successive strata so that the canopy becomes continuous between the ground and upper tree crowns
-some species grow sub canopy branches by epicormic sprouting

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horizontal diversification

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-gap creation and expansion results in horizontal spatial heterogeneity
-understory is variable with sun flecks and highly shaded areas

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pioneer cohort loss

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-shade-intolerant pioneer species do not regenerate successfully in gaps and are lost from the stand as individual trees die

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silvics

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-ecological study of forest trees
-life history and general characteristics of forest trees and stands
-environment + genetics
-basis for the practice of silviculture

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silviculture

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theory and practice of controlling the establishment, composition, growth and structure of forests

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role of silvics in forest management

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management and restoration of forests, maintaining/promoting desired attributes:
-tree species choice, methods of regen & cultivation, effects of productivity and site quality

requires knowledge of:
-ecological characteristics of tree species and environmental effects on tree behaviour and growth

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silvicultural systems

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-program of treatments for a whole rotation
-determined by management objectives and site features
-multiple steps: pre-harvest prescription; regeneration cutting method - harvest system, site preparation, regen; post-regen treatments: brushing, spacing, pruning, fertilization, thinning, pre-commercial thinning

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regeneration cutting methods

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silvicultural systems are named by method of regeneration cutting used to replace a forest stand
-systems that create even-aged stands: clear cutting, seed tree, shelterwood
-systems that create uneven-aged stands: group selection, single-tree selection, patch cuts
-hybrid systems: variable retention silviculture

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clearcut systems

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harvest an entire stand of trees in single harvest:
-area >= 1 ha, and > 2 tree heights in width, >50% open area climate (not influenced by edge)

regeneration
-even-aged stand by planting, natural or advance regen, direct seeding
-shade-intolerant or exposure-tolerant species
-species that grow on a range of substrates with fast initial growing rates

reserves
-trees retained for objectives other than regen

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seed tree system

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selected trees or tree groups left during harvest
-provide seed source for natural regen
-even-aged system, creates single or double cohort
-after natural regen, seed trees may be cut

Regeneration
-shade-intolerant or exposure-tolerant species
-important factors: spatial configuration, timing of cut and site prep

criteria for leave trees
-large, dominant trees
-windfirm - topographic position, exposure within patch or along edges
-tree roots, stem and crown
-good seed source

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shelterwood systems

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mature trees removed in a series of cuts over 20-30 yrs:
1) prepatory cut - leave windfirm trees, increases growth and cone production
2) seed cut - create gaps for regen, provide protection and seed; new cohort(s) regenerated under the shelter of remaining trees, regen may be planted, natural or advance
3) removal cut - after regen achieved, shelter no longer needed

regeneration
-shade-tolerant or protection-requiring species
-provide seed for natural regen
-retained mature trees released = generate volume increments for subsequent harvest

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types of shelterwood systems

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-uniform
-group
-nurse-tree

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uniform shelterwood

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-individual residual trees are uniformly dispersed
-ideal for shade-tolerant trees
(retention % creates: 20-25% cool seedbed, ~30% moist seedbed, >50% protection from frost)

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group shelterwood

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-residual trees are clustered
-harvest to create gaps and small patches to facilitate natural regen +/- planting

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nurse-tree shelterwood

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-mixed species, protects regen
-two canopy strata (2+ species)
-overstory: from original stand or established after cutting

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silvicultural systems creating uneven-aged stands

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-harvest at specified repeated intervals
-harvest single scattered individuals or small groups of trees
-encourage relatively frequent establishment of regen in canopy gaps
-encourage and maintain an uneven canopy and an uneven-aged stand structure

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single-tree selection

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-remove 1+ trees of a range of sizes = small gaps, cutting cycle 1-10+ yrs
-regen very shade-tolerant species to create multi-cohort stands
-heli-logging
-risk of high grading and reducing chance of high quality regen

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group selection

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-cut trees in defined groups, openings <2 tree heights wide
-shade-intolerant trees can regen with shade-tolerant species
-creates multi-cohort stands

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patch cut system

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-openings <1 ha in size
-creates small even-aged stands (fine-scale), uneven-aged at coarser scales
-does not depend on shelter incidentally provided by the surrounding uncut stand

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hybrid silvicultural systems - variable retention

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fundamental objective:
-reduce ecological impact by retaining biological legacies (structural diversity)

components of even-aged and uneven-aged regen silvicultural systems:
->50% of opening <1 tree length from an edge
-irregular boundaries and retention of trees provides "forest influence"
-regn usually even-aged, natural, or planted