• Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off

Card Range To Study



Play button


Play button




Click to flip

Use LEFT and RIGHT arrow keys to navigate between flashcards;

Use UP and DOWN arrow keys to flip the card;

H to show hint;

A reads text to speech;

140 Cards in this Set

  • Front
  • Back
ecosystems constantly changing, disturbed
-never in equilibrium with current environment

temporal patterns that occur in ecosystems differ with scale of observation & severity of disturbance
Ecological Succession
process of ecosystem development
-can result from developmental changes in ecosystem itself or from disturbances
characteristic sequence of biotic communities that follow another in a particular environment
seral stages
various communities that together make up a sere,
each is floristically distinct
Autogenic succession
*most common
resident organisms change physical environment
allogenic succession
geological processes cause change
biogenic succession
sudden interference by living organisms (herbivore, pathogen)
primary succession
occurs on newly exposed land
-initiated by disturbance that exposes substrates and are left with essentially no plant growth at start
-sever disturbances
-glaciations, volcanic ash deposition, catastrophic wildfire
secondary succession
occurs when vegetation is cleared but soil remains
-can start in mid-succession and then to final climax
-moderate disturbances
-after wildfire, wind, logging
succession results in
"a rich, dynamic tapestry of vegetation, providing an array of habitats for animals and microbes"
-Perry, 1994
Relay Floristics
-concept of seral stages
-each stage prepares habitat for the next one, often through changes to soil.
3 steps:
-primary succession colonizers
-secondary succession colonizers
-late successional species
Pioneer community traits
harsh environment
increasing biomass
some loss of nutrients
low diversity
energy consumption inefficient
r-adapted (energy into reproduction, rapid growth)
climax community traits
moderate environment
nutrient cycling
high diversity
energy consumption efficient
fluctuations rare
biomass stable
K-adapted (energy into biomass not reproduction)
shade tolerance
-Tolerant (T)
-Intolerant (I)
Intermediate (N)
ability of a tree to grow in the shade of other trees
T = grow well in low light, do not show large increase with increasing light lvls. Climax species.
I = cannot grow well in low light, grow very well in high light. Pioneer species
N = intermediate in ability to grow in the shade
progressive succession
shows increase in biomass, diversity and structural complexity
-trend towards being a mesic site
retrogressive succession
shows decrease in biomass and diversity
-trend towards becoming a hydric or xeric site
process of mire (peat forming ecosystem) formation in an area that used to be forested or a grassland
-autogenic or climatic processes leading to waterlogging and anaerobicity
carbon dynamics in primary succession
initially: low O.M. content, CEC, moisture holding capacity, decomposition
mid succession: rapid decomp., increases in soil carbon and nutrient inputs
late succession: decomp. slows, reduced rates of soil carbon & nutrient inputs
Carbon pools & Primary succession
increases then plateaus
C-Flux, Early: NPP & NEP increases as O.M. increases; heterotrophic resp. lags NPP.
C-Flux, Late: NPP = heterotrophic resp; NEP declines to zero. Eventually NEP affected by climate & gap phase disturbances
Carbon pools & secondary succession
initial C pool & flux after large disturbance: plant C pool decreases, Soil C pool increases or decreases

C-Flux, Early: NPP recovers quickly because of increase in resource availability; decomp. rapid because of increase in labile C, temperature and water availability
NEP negative because of high C loss, decomp., and low NPP
Nutrient Cycling in Primary Succession
post-disturbance: high nutrient loss, then accumulation due to large biomass increment & N fixation
mid-succession: essential/limiting nutrients retained most strongly in biomass, little loss
late-succession: system stabilizes; nutrient outputs = inputs; NEP = 0
nutrient cycling in secondary succession
pulse of nutrient availability after disturbance
(fires increase N availability, susceptible to loss)

Fate depends on retention mechanisms:
-plant uptake
-microbial uptake
-chemical fixation
Temporal dynamics in ecosystems
(other than succession)
temporal extrapolation requires understanding of timescale of variables affecting processes
-multi decadal
fluxnet Canada
research on climate, disturbance & C cycling in canadian forests/parklands
-N carbon sink absorbs 15-30% of global C
diurnal cycles
NEP negative at night, positive during day
weak cycle = disturbed sites, mature conifer stands & peatlands
strongest cycle = intermediate ages & deciduous forests

disturbed sites = net source
intermediate/deciduous forests = net sinks
seasonal fluctuations
-plants senesce in autumn (in response to photoperiod)
-grow rapidly in spring
-when GEE begins early = net sink
Net Ecosystem Exchange (NEE) = PS rate (GEE) + respiration rate (R)

GEE begins in spring, increasing as nighttime temps warms (through Oct)

NEE ceases midsummer due to increasing respiration
inter-annual fluctuations
Pacific Decadal Oscillation (PDO)
-N. Pacific
-phases of 20 - 30 yrs
-positive phase since 1977

Atlantic Multi-decadal Oscillation (AMO)
any relatively discrete event in space and time that disrupts ecosystem, community, or population structure & changes resources, substrate or the physical environment
disturbance properties
Magnitude: size or spatial extent of event

Intensity: force of the event

Severity: defined in terms of it's killing effect; measures the impact of the event on system properties
exogenous disturbance
those originating from outside the system
endogenous disturbance
those originating from within the system
indirect disturbance
doesn't kill individuals
alters resource levels or other factors influencing individuals
direct disturbance
killing disturbance
death of individuals, opens space & releases resource to others
biotic disturbance
disturbance agent is a living organism
abiotic disturbance
disturbance agent is not a living organism
Insects: anthropogenic contributions to susceptible trees
-effective fire suppression (<1% of historic area currently burns)
-selective harvesting (<1970 lodgepole a 'weed')
-overabundance of mature pine (>3X susceptible hosts)
tree biology w.r.t. pine beetle
beetles prefer large trees:
- high quality food & larval habitat
-protection from natural enemies & weather extremes

large trees tend to be more resistant
-con-situate resin ducts
-induced resin production
pine beetle
biology basics
colonizing beetles emit aggregation pheromones
-resultant mass attack overwhelms tree defences

beetles also introduce blue-stained fungi
-pathogenic to most trees
-block vascular tissue, stop resin production
-provides nutrients for maturing beetles
pine beetle
current outbreak + predictions
area affected = 18 million ha

mortality of 60% of mature pine by 2020
endemic populations
-insufficient beetles to colonize healthy trees
-normally found in trees attacked by others
-attacked trees rare and scattered
-mortality and off spring in balance
(97.5% mortality)
beetle mortality factors
host resistance
-relaxation of one or more of these factors allows population to build and move from endemic to incipient to epidemic populations
incipient populations
-infestations scattered
-number of trees infested increases annually
-clumps of infested trees grow in size and number over time
-most attacked trees in larger diameter classes
(95.0% mortality)
epidemic populations
-large annual increase in infested areas
-extremely resistant to losses through normal mortality
(80 - 95% mortality)
causes of outbreak
abundant susceptible hosts

climate favouring beetle survival
model of climatic suitability (beetles)
P1: sufficient heat accumulation for synchronized one year life cycle

P2: minimum winter temperatue >-40C

P3: average maximum August temp >= 18C

P4: total ppt from April to June below long term average
outbreak consequences
forest C dynamics:
decrease C uptake (trees dead)
increase in C emissions from decaying
fire suppression paradox
Stand initiating fires + fire exclusion
leads to: fuel buildup
leads to: unusually severe fires
leads to: human costs and economic losses

mitigation: thinning, prescribed burns
human impacts on fire regimes
due to historical data we expect evidence of a fire every 20 years

1945 - 2005 there no evidence or fires
Fire: Lessons Learned
historical fires in mountains
-low to high frequency and severity

human and climate influences on fire:
-fire free period = mostly fire suppression
-global climate influences drought & fire
-current forests and fuels
-natural processes & fire suppression effects
-major disturbance in coastal BC
-windthrow plows soil, creates microsites
-creates uniform, multi-cohort or all aged stands
-maintains structurally diverse lanscapes
-should be recognized in planning
turning moment
+ factors
function of lever arm length and gravity

-wind speed
-crown size/density/mass
-stem mass/elasticity
-tree height
-tip displacement
tree resistance to wind
by having a thick stem and good root system
-taller tree = longer lever arm, therefore need to counteract turning moment accordingly by increasing stem and root system

also: stream lines in the wind with branches deflecting to be aerodynamic and more porous
Armstrong Technique
test tree resistance to wind by pulling down with winch + cable

critical turning moment = max resistance of tree before it falls
"slenderness ratio"
height/diameter ratio
-low (<60) = stocky
-high (80-100) = tall/skinny
worst soil for tree stability
fertile but shallow
-lots of biomass accumulation above ground
-unable to get a good deep root system
wind + hills
wind acceleration (top speed) @ crest
turbulence on leeward side

most windthrow happening at crest
Stand Level Effects of Wind
wind disturbance can perpetuate themselves by creating stands that are high competition therefore tall & skinny and susceptible to further wind throw

-profound effects on soil: turning, can reverse paludification, adds woody debris to stream beds and helps structure them
Landscape Level Effects of Wind
smaller lower on the slope; wind throw @ crests
landslides mid-steep slope, paludification on lower slopes
hypermaritime: most productive areas mid slope
The disease triangle
need three things:
susceptible tree host (native vs. introduced)
virulent pathogen (native vs. introduced)
conducive environment (environment/climate change; man made perturbances)
Pathogens as Good Guys
-create stand openings
-increases diversity
-increases resilience
-wild-life habitat
-nutrient cycling

effect of the disease on the host, host reaction

the pathogen itself
Disease Epidemic Causes
forest (mis)management
invasive alien pathogens
-see disease triangle
Fungi Roles
-decomposition of cellulose and lignin
-C and nutrient cycling
-mycorrhizal associations with plant roots
-water, nutrient exchanges, protection
Food for wildlife
Categories of Forest Pathogens
-root rots, wilt
Decay Fungi
-brown/white rot
Disease Prevention
-learn to recognize pathogens, conduct proper diagnosis
-understand pathogen biology, survival, dissemination
Disease Management
-know toolbox of options
Deer & Haida Gwaii
sitka black tailed deer
-introduced in 1876 by Revd Collison as a source of meat
-mild climate, abundant food,no competition, no predators
-exponential population growth with minor dips due to food shortage, weather, disease
-helped by clearcut logging, abundance of forage
cost & benefits of introduced species
biological impacts of most negative (cause a decrease in diversity)
on haida gwaii: decrease in W. red cedar, shrurbs & wildflowers; increase in hemlock & spruce.

economic & cultural value may be positive
-clearings, grassy meadows preferred over impenetrable shrubs; hunting
Ecological Impacts - Introduced Species
Effects on Insects
-vegetation and litter fauna
Understory fauna
-deer decreases resource quantity and quality
Negative Feedback
-lack of pollinators decreases plants further
Litter Fauna
-deer decrease resource quality: decreasing deciduous litter, increasing conifer litter, decrease protection from elements
-increase millipedes, decrease snails/slugs - has an effect on decomposition rate/completeness
water cycle
driven by solar radiation that generates evaporation & atmospheric circulation

-canopy interception
-water tables
Orographic PPT
result of topography
geography and prevailing wind direction matter
important in BC
Frontal/Cyclonic PPT
large weather systems
created by convergence of air masses
longer, affects relatively large regions
Convectional Rainfall
summer thunderstorms
Evaporation Factors
driven by solar radiation E
water vapour pressure
vapour pressure deficit (VPD)
Solar Radiation Energy
provides energy required to convert water from liquid to gas phase
creates wind which can cause convective evaporation
heats air mass and increases water holding capacity of air
Water Vapour Pressure
measure of amount of water vapour in air
function of air temp and available water
saturation vapour pressure = @ equilibrium with the liquid phase
actual vapour pressure = a value btwn 0 and saturated vapour pressure
Vapour Pressure Deficit (VPD)
measure of drying potential of air
difference btwn actual vapour pressure & saturated vapour pressure at a given temperature
inversely related to relative humidity (%)
(as RH increases VPD decreases)
Canopy Interception
Depends on
-leaf are index
-rainfall intensity
Surface Evaporation
Depends on
-quantity of solar radiation reaching forest floor
-water holding capacity of surface litter (LFH layers)
Soil Evaporation
sames as surface area evaporation plus:
-mineral soil particle size
Plant-Air-Soil continuum
because of pressure gradient trees act like a wick drawing water from soil into atmosphere
-leaves act as pump, water into roots and up the stem
-water moves up through xylem with hydrogen bonding cohesion
-soil water moves toward roots along pressure gradient
(plant community ecology)
an assemblage of species that live in an environment and interact with one another, forming a distinctive living system with it's own composition, structure, environmental relations, development and function
distinct variant of phenotypic characteristic of an organism
-may be inherited, environmentally determined or a combo of the 2

rooting depth = characteristic
shallow/deep roots = trait
degree of variation of life within an ecosystem, biome or planet
-richness, evenness
Species Interactions
mutualism (+, +)
predation/parasitism (+, -)
competition (-, -)
commensalism (0, +)
amensalism (0, -)
neutralism (0, 0)
(-, -)
individuals using same resources will compete if that resource is in short supply
-results in niche partitioning
(+, +)
both interacting partners benefit from the relationship
-believed to be the most common interaction in nature by some ecologists
(0, -)
a relationship where a product of one organism has a negative effect on another
-ie/ alleopathy
different organisms living together
-usually in close association with one another to the benefit of one or more of them

mutualism (+, +)
Parasitism (+, -)
Commensalism (+, 0)
Amensalism (-, 0)
Impact of Organisms Depends On:
number; richness (each species unique, some species ecologically similar)
abundance; evenness (rare species, dominant species)
ID; composition (compensating species, keystone species)
Functional Groups
groups of species that are similar in traits and in effects on ecosystem processes
(ie/ N-fixing bacteria, deciduous trees)

-helpful in predicting effect of species losses on ecosystems, draw generalities
Functional Groups Caveat
no two species within group are exactly alike
-species competing for same resource cannot stably co-exist: one will take over, leading to extinction or shift towards different ecological niche of the other
Foundational Species
dominant species whose:
"architecture and functional ecology define forest structure and whose species specific traits control ecosystem dynamics"

-any tree when it is functionally unique
-change in these species more likely to have ecosystem effects than change in rare species
Keystone Species
Species that are more important to ecosystem processes than their abundance might suggest
-affect many other organisms in an ecosystem
-help to determine types & numbers of various other species in a community
Effects of Species Diversity
-enhance efficiency of resource use
-stabilize ecosystem processes in a variable environment
-insurance against radical ecosystem changes
Temporal Ecosystem Dynamics & Resilience
ecosystems are constantly changing and disturbed
-they are never in equilibrium with the current environment
-temporal patterns that occur differ with scale & severity of disturbance observed
-response of ecosystem to perturbation depends on 6 properties
Ecosystem Response to Disturbance Depend on:
tendency not to change
-ability to absorb disturbance
-maintain certain structures & functions
direction and magnitude of change
extent of return to original state
rate of return to original state
elasticity or ability to return to original state
-measure of amount of disturbance system can absorb without leaving stability domain
amount of perturbation a system can tolerate without changing state
Balls & Peaks
pushing ball into new domain depends more on the way that it is pushed (even subtle) than how hard
-rapid threshold changes or exceeding "tipping points" can occur without warning
-low reversibility: in reality species loss begets more species loss
Cup and Ball
width of cup = range of natural variation (RONV)
management goal is to make sure we don't push the ball out of current stability domain
how does decreasing biodiversity destabilize ecosystems?
1) declining species richness lowers ecosystem function
2) at least one functional group, preferably with redundancy, essential to ecosystem stability
3)the nature of response to species loss depends on which species is lost
-degrading system (or pushing out of RONV = loss of stability
a functional system that includes an assemblage of interacting organisms and their environment; which acts on them and on which they act
Ecosystem Ecology
integrated study of biotic & abiotic components of ecosystems and their interactions with ecosystem framework
ecosystem classification
tool for understand & predicting responses of ecosystems occupying a given site
Attributes of Ecosystems
structure (components)
function (processes)
intangible geographic boundaries
change over time
structure (components)
-plants, animals, microorganisms
-substrate (soil), atmosphere, water
-producers, consumers, decomposers
-food web
function (processes)
-constant exchange of matter and energy components
-Energy flow
-nutrient cycling
-water flux
components interact and are interdependent
-high level of integration
-multiple feedbacks: positive (enforcing) & negative (dampening)
-all events and conditions have multiple determinants
Intangible Geographic Boundaries
-connected to other ecosystems
Ecosystem Change Over Time
-not static in composition, structure or function
-altered from within (plant species effect)
-altered from without (fire, climate change)
-change within bounds determined by climate, site
Natural Disturbances
exogenous and endogenous
are an integral part of ecosystems, and more often than not are agents of renewal rather than destruction
-within historic range of variability
-some human disturbances are in this range
Foreign Disturbances
of a type or severity to which native species are maladapted, can be serious threat to ecosystem integrity
-may force system past a threshold into new regime
-degraded conditions
-become increasingly prevalent
- includes: uncommonly severe fires, climate change, & invasive species
Maintain Ecosystem Integrity
-maintain key ecological processes that reflect their natural condition
-manage population of species to levels with high likelihood of maintaining themselves
-maintain diversity of genes, species & communities native to region
Prevent or Minimize Ecosystem Change
Keep disturbances within historic range
-w.r.t. type and severity
-use forest practices that emulate natural disturbances
Prevent soil degradation
Maintain hydrology (water flux)
Foster resilience of ecosystems
Managing for Resilience
-ecosystem level
-maintain desirable species an control undesirable species

-landscape level
-maintain heterogeneous landscape with large and structurally complex patches of native vegetation connected by corridors
Process Strategies
1) maintain key species interactions and functional diversity
2)apply appropriate disturbance regimes
3) control aggressive, over abundant and invasive species
4) minimize ecosystem specific threats (pollutants, hunting)
5)maintain species of particular concern (keystone, rare)
Pattern Strategies
1) maintain and create large, structurally complex patches of native vegetation
2) maintain structural complexity throughout landscape
3) create buffers around sensitive areas
4) maintain/create corridors and stepping stones
5) maintain landscape heterogeneity and capture environmental gradients
Managing for Complexity
to foster resilience
-promote landscape connectivity
-retain or restore areas that may be buffered against climate change
-plant mixes of trees to reset successional patterns
-facilitate species (and population) migration and range shifts
-develop harvest, regeneration, & stand tending that maintains or enhances complexity
Ecological Restoration
-returning ecosystem to desired state
-usually a reference ecosystem or historical reference
-restoration attempts to return an ecosystem to its historic trajectory
Restoration Ecology
the science on which the practice of ecological restoration is based
Attributes of a Restored Ecosystem
1) characteristic assemblage of species
2) indigenous species
3) all functional groups required
4) physical environment capable of sustaining reproducing populations
5) functions normally
6) integrated into larger ecological matrix
7) potential threats lowered
8) resistant
9) self sustaining
Dilemmas in Ecosystem Restoration
1) where to set ecological reference
2) historical reference often not achievable
3) exotic species often unavoidable
4) exotic species contribute to ecosystem function
5) novel ecosystem the way of the future?
6) does it imperil conservation?
reparation of ecosystem processes, productivity and services
objectives include stabilizing the terrain, assuring public safety, improving aesthetics and returning land to a useful purpose
normally a component of land reclamation, often entails the establishment of only one or a few species
compensates environmental damage
installing a different type of ecosystem from that which historically occur
Ecological Engineering
manipulation of natural materials, living organisms and physical-chemical environment to achieve specific human goals and solve technical problems
Landscape Ecology
incorporates the dimension of space into ecological studies
-heterogeneity in ecosystems across space influence ecological processes
-ecosystem services vary across space
Landscape Ecology & Management
1) maintain and create large structurally complex patches of native vegetation
2)maintain structural complexity throughout the landscape
3) create buffers around sensitive areas
4) maintain/create corridors and stepping stones
5) maintain heterogeneity & capture environmental genetics
-nonlinear surface areas that differ in vegetation and landscape from their surroundings
-dominant component of the landscape
-most extensive and connected landscape type
-dominant role in landcape ecology
Linear, connect patches
Categories of Ecosystem Services
Provisioning Services
-food production, water, wood and fiber, fuel
Cultural Services
- spiritual, aesthetic, educational, recreational
Supporting Services
-nutrient cycling, soil formation, primary production, habitat provision
Regulating Services
-climate regulation, flood regulation, water purification
Location Matters!
(Landscape Ecology)
-incorporates the dimension of space into ecological studies
-heterogeneity in ecosystems across space influence ecological processes
-ecosystem services vary across space