Final Flashcards
(212 cards)
1
Q
What is a community?
A
all populations of species living together in a
particular area
2
Q
Challenges of measuring an ecological
community:
A
- Difficult to count ALL species present
-Therefore, often specify - all plant species, frugivore community - Community boundaries often gradual
- Species can move in and out of communities
3
Q
What do we mean by Community structure?
A
1) which species are in the community
2) what is relative abundance of each species
3) what are the relationships among the species
4
Q
Ecotone
A
-changes in the environmental conditions
-ex: soil type, geology, water
- aspect, disturbance (grazing, plowing)
a boundary created by sharp changes in environmental conditions over a relatively short distance, accompanied by a major change in the composition of species
5
Q
Detecting an ecotone:
A
run a transect from non-serpentine to
serpentine
- note which species are present at each point
along the transect - ecotone – where we see a shift from one set
of species to another
6
Q
What is serpentine soils?
A
low nutrients, high in metals
7
Q
interdependent communities
A
communities in which species depend on each other to exist
8
Q
independent communities
A
communities in which species do not depend on each other to exist
-species just happen to live together cuz they have similar requirments/adaptions
9
Q
What is species richness?
A
the number of species in a community
10
Q
Why is species richness often higher at an ecotone than not at an ecotone?
A
-generalists can live there and some of the species from each of the 2 communties xan live there
- overlap between communties
11
Q
Community structure:
A
- Which species are in the community?
- What is the relative abundance of each
species? - What are the relationships among species?
12
Q
abundance:
A
the number of individuals
13
Q
relative abundance:
A
the proportion of all individuals represented by each species
14
Q
What is species evenness?
A
-evenness is highest when all species have equal abundance
a comparison of the relative abundance of each
species in a community
15
Q
Rank-abundance curves
A
plot the relative abundance of each species in a
community in order from most to least abundant
steeper = less even
never a complete even species
16
Q
log-normal distribution
A
a normal, or bell-shaped, distribution that uses a log scale on the x-axis
17
Q
Diversity indices:
A
a way to compare the diversity of communities that takes into account species richness AND evenness
18
Q
Simpson’s index:
A
a measurment of species diversity, given by formula on page
19
Q
Shannon’s index:
A
a measurment of speices diversity given by formula on page
20
Q
intermediate disturbance hypo
A
found that hump-shaped relationships found in <20%
the hypo that more species are present in a community that occasionally experiences disturbances than in a community that experiences frequent or rare disturbances
21
Q
(1) Productivity (resources)
A
species richness can be affected by the the amount of resoucres available (soil nutrients)
- productivity is measured by biomass = more resources
- relationships found in nature between productivity and species richness: hump-shaped is most common
22
Q
Ecologists have found that-
A
as more and more resources are added, the number of plant species goes down
23
Q
What causes more and more resources that are added, the number of plant species goes down
A
at high levels of resources, it allows a few dominant competitors to outcompete the other species
24
Q
whether the relationship between productivity and species richness looks positive, negative, or hump-shaped can depend on -
A
the RANGE of productivity in the experiment
25
Habitat diversity
- communities with a greater diversity of habitats
-habitats tend to have more species
- more niches available
26
Keystone species
- the presence of a keystone species can lead to greater species richness (even if that species is not very abundant)
27
Disturbance
Can also affect species richness in a community
ex: hurricanes, wildfires, logging, ploughing
ecologists agree that disturbance (type, severity, frequency) affects community structure
- but the IDH is controversial
28
What local factors can affect community species richness?
(1) The amount of resources (productivity)
(2) Diversity of the habitat
(3) Presence of keystone species
(4) Disturbance intensity or frequency
29
food chain
a linear representaion of how different species in a community feed on each other
30
food web
a complex and realistic representaion of how psecies feed on each other in a community
-who eats whom?
31
Why do ecologists want to know who eats who?
-understand feeding relationships
-how one species change in abundance can affect another
-weather a species can survive in an area
-what would happen if one species goes extinct
32
Trophic levels:
a level in a food chain or food web of an ecosysytem
- all species in a trophic level get their energy
in a similar way
33
When discussing trophic levels, a guild is:
a group of species that feed on similar items.
34
Do species in the same guild have to be closely related?
no,
-ex, ants and rodents
35
primary consumer
a species that eats producers
36
secondary consumer
species that eats primary consumers
37
tertiary consumers
a species that eats secondary consumers
38
omnivore
a species that feeds at several trophic levels
39
Types of indirect effects
Density-mediated
Trait-mediated
40
Density-mediated
- caused by changes in the DENSITY of intermediate species
-fish eat dragonfly larve = less dragonfly density= less predation on pollenators
41
Trait-mediated
- caused by changes in the TRAITS of the intermediate species
-mediated
-behaviour
42
indirect effects
an interaction between two species that involves one or more intermediate species
43
direct effect
an interaction between two species that does not involve other species
44
trophic cascade
indirect effects in a community that are initaiated by a predator
45
density-mediated indirect effect
an indirect effect caused by changes in the density of an intermediate species
46
trait mediated indirect effect
an indirect effect caused by changed in the traits of an intermediate species
47
community stability
the ability of a community to maintain a particular structure
48
community resitance
the amount that a cmmunity changes when acted upon by some disturbance, such as the addition or removal of a species
49
community resilience
the time it takes after a disturbance for a community to return to its original state
50
alternative stable state
when a communtity is disturbed so much that the species composition and relative abdundance of populations in the community change, and the new community structure is resistant to further change
51
bottom up effect
happens at the bottom and affects all
52
top down effect
or "tropic cascade"
53
what regulates populations?
both top down and bottom up together
(1) the world is green (plants are doing well!), therefore, something must be controlling the herbivore populations
(2) that must be the predators
(3) therefore predators are the most important (top-down control)
54
Succession:
the process by which the species composition of a community changes over time
55
Seral stage:
each state of community change during the process of succession
e.g. early seral, late seral, climax community
56
Climax community:
the final stage in succession
does not mean permanent or totally stable
57
Pioneer species:
the first species to arrive at a site
-get succession going (partly started)
58
how can we study succession?
1) direct observation
2) indirect observation
59
chronosequence (indirect)
a series of sites that differ in age since abandonment or disturbance, but otherwise occur on similar soil types and environmental conditions
land rising up gradually
-farther from water= older communities
60
direct observation
-keep returning to the same site overtime and record which species are there
61
ASSUMPTIONS for Chronosequence
1) every site foes through the same stages
2) the sites vary in AGE only
ex- same climate, same rock underneath
62
Indirect methods
- Chronosequence (space for time)
- Paleoecological methods
63
Paleoecological methods
can use instead of chronosequence
Paleoecology is the study of the relationship between extinct organisms and their environments.
-pollen in lake sediments
-tree rings
64
Observe it directly over time pros and cons
PRO: no assumptions of space-for-time
CONS: 1) have to wait a long time (especially long species like trees)
2) maybe have only 1 example (n=1)
65
Indirect methods pros and cons
PRO: takes less time!
CONS: 1) have to make assumptions
2) paleoecological proxies have variable resolutions
- ex, cant differentiate to species, maybe only to genus using pollen for trees
66
Why might direct observation of succession be easier in intertidal communities than in terrestrial communities?
Organisms in an intertidal area have shorter generation times than organisms in terrestrial communities.
67
Types of succession in terrestrial
environments:
Primary succession
Secondary succession
68
Primary succession
“start from scratch”
- habitats start with NO plants and NO organic soils
sand dunes, lava, bare rock, volcanic ash
69
Secondary succession
habitat has been disturbed, no plants but DO have organic soils and could have seeds or roots
plowed fields, forest fires
70
Species traits: for early seral
seeds = many
seed size = small
dispersal mode = wind/ stuck to animals
seed viability = long
root:shoot ratio = low
Growth rate = fast
Size = small
Shade tolerance = low
71
Species traits: for late seral
seeds = few
seed size = large
dispersal mode = gravity/ eaten by animals
seed viability = short
root:shoot ratio = high (many roots)
Growth rate = slow
Size = large
Shade tolerance = high
72
What causes succession?
Why does the composition of the community shift over time?
-condtions are changing (light, soil)
-caused by other species
Facilitation:
Inhibition:
73
Facilitation:
the presence of one species INCREASES the probability that a second species can become established
-ex, alder trees, n-fixing creats greater n availabliity in soil, which allows spruce to colonize
74
Inhibition:
the presence of one species DECREASES the probability that a second species can become established
ex- maple and beech trees casting deep shade prevents early seral from growing there
75
What is NOT an example of inhibition?
A species acts as a nurse plant and increases water available to other species.
(its helping so no)
76
How can you determine whether a particular species is FACILITATING or INHIBITING another species? (or, neither?)
HYPOTHESIS: acorn barnacles are facilitating macroalgae
if the hypothesis is true, then areas with acorn barnacles removed will have significantly lower density of algae than the control after 2 years
77
“Climax” communities are not unchanging
-small disturbances can create shifts in species composition
- e.g. old tree dies, falls = GAP
- gap can be colonized by early-seral species
- community overall is in late-seral stage, but has some early-seral species due to the gap
78
what is a GAP
pockets of early succession
79
priority effect
when the arrival of one species at a site affects the subsequent colonization of other species
80
transient climax community
a climax community that is not persistent
81
fire-maintained climax community
a successional stage that persists as the final seral stage due to periduic fires
82
grazer-maintained climax community
when a successional stage persists as the final seral stage due to intense grazing
83
Primary productivity:
The rate at which solar or chemical energy is captured and converted into chemical bonds by photosynthesis or chemosynthesis
84
Standing crop:
the biomass of producers present in an ecosystem in a given area and at a particular moment in time
85
gross primary productivity (GPP)
the rate at which energy is captured and assimilated by producers in an area
86
Net Primary productivity (NPP)
the rate of energy that is assimilated by producers and converted into producer biomass in an area
87
How can we measure Net Primary Productivity (NPP)?
(1) measure the biomass of producers at the beginning and at the end of a growing season
(2) Measure the uptake and release of CO2 by producers
(3) Measure the uptake and release of
O2 by producers
(4) Remote Sensing
88
measure the biomass of producers NPP assumptions
no losses to herbivory and disease
also often/usually measure only above - ground biomass
89
Measure the uptake and release of CO2 by producers examples
1) put a plant in a jar, measure co2 uptake in the light = NPP
-repeat in dark - to estimate co2 production from respiration
GPP = NPP + respiration
2) do on a larger scale, using flux tower- measure co2 concentrations at different heights
90
Measure the uptake and release of O2 by producers- why not CO2, how
can’t measure CO2 in aquatic systems, because:
co2 = biocarbonate ions
-put water with algae in a jar
- in light: measure o2 produced (NPP)
-in dark: measure o2 consumed - respiration
91
Remote Sensing how
-for very large scales
- photos or imaging from a plane/satellite
-reflections of green light- if high that means high standing crop
-measure change over time to measure NPP
92
eqested energy
the portion of consumed energy that is excreted or regurgitated
93
assimilated energy
the portion of energy that a consumer digests and absorbs
94
respired energy
the portion of assimilated energy a consumer uses for respiration
95
net secondary productivity
the rate of consumer biomass accumulation in a given area
96
What limits NPP?
1) temperature
2) precipitation
3)nutrients
4) light
97
temperature limitaion
-as mean annual temperature increases, NPP increases.
wHy? - warmer, = longer growing season
= higher productivity
98
precipitation limitation
NPP peaks around 3m of annual precipitation
at low precipitation levels, NPP also low
with very high precipitation, NPP is low again
nutreints leaching out of soil + low decompostion in waterlogged soils (low nutrients)
99
nutrients limitations
-need nutrients like N + P to make important molecules (protiens)
-low nutrients = low NPP
-in oceans, NPP can also be limited by lack of silicon + iron
100
light limitations
in water- deep underwater = not much light
101
NPP around the world
-highest NPP in the tropics (near equator)
-shallow areas near coastlines
-shallow = more availability
-nutrients from land
102
what is detritus
not consumed (leaves)
103
why total energy declines as you move up trophic levels from producers to tertiary
consumers.
At each level energy is lost to
-non-consumed tissue (detritus)
-non-digestiable tissue (egested)
-respriation
104
egested
non digestiable tissue
105
trophic pyramid
a chart composed of stacked rectangles representing the amount of energy or biomass in each trophic group
106
pyramid of energy
a trophic pyramid that displays the total energy existing at each trophic level
107
pyramid of biomass
a trophic pyramid that represents the standing crop of organisms present in different trophic groups
108
Ecological efficiency
the percentage of net production of one trophic level compared to the next level down
109
Assimilation efficiency:
the percentage of consumed energy that is assimilated (and then goes to either respiration OR growth and reproduction)
110
consumption effciency
the % of energy or biomass in a trophic level that is consumed by the next higher trophic level
111
net production efficency
the % of assimilated energy that is used for growth and reprocuction
112
flow of NUTRIENTS
-flow through ecosystems in cycles
-not lost, recycled
113
what is nitogen used for?
amino acids, nucleic acids
114
What is phosphorus used for?
bones, scales, teeth, DNA, RNA, ATP
115
What is sulphur used for
proteins (cysteine)
116
what is potassium used for
enzymes
117
what is calcium used for
bones + teeth, muscles contraction
118
what is magnesium used for
many enzymes, chlorophyl
119
what is iron used for?
hemaglobin, needed to make chlorophyll
120
The hydrologic cycle
the movement of water through ecosystems and atmosphere
121
The hydrologic cycle main processes
evaporation:
transpiration:
precipitation:
infiltration:
run-off:
122
evaporation:
solar energy heats water, changes to gas
123
transpiration:
water vapour from plants
124
precipitation:
returns to land (rain)
125
infiltration:
percipitates through soil into the ground water (eventually to ocean
126
run-off:
runs off land surface into lakes/rivers/oceans
127
How does human activity affect
the hydrologic cycle?
1) pave surfaces
2) global warming
3) use ground water for irrigation
4) use freshwater for households
5) destroy forests/grasslands
128
How does paving surfaces affect the hydrologic cycle
increases run-off, decreases infiltration
129
How does global warming affect the hydrologic cycle
increased evaportaion, more precipitation
130
How does using ground water for irrigation affect the hydrologic cycle
depletes groundwater
131
How does using freshwater for households affect the hydrologic cycle
irrigation, industry, humans use ~50% of accessible freshwater run-off
132
How does destroying forests/ grasslands affect the hydrologic cycle
less transpiration, more run-offs
133
Processes that add carbon dioxide to the
atmosphere:
- respiration
-fires + volcanoes (compustion)
-combustion of fossil fuels
134
combustion of fossil fuels =
CO2
concentraion is 30% higher than preivous maxiumum levels
135
CO2 absorbs infrared radiation, reflects back to earth =
warmer "greenhouse effect"
136
The Nitrogen Cycle:
biggest pool of N = N2 in atmosphere
137
N-fixation:
the process of converting N in atmosphere into forms that producers (plants) can use
138
N-fixation is done by
some cyanobacteria
some freeliving bacteria
some mutualistic bacteria
also lightning combustion and fertilizer production
139
How does human activity affect
the nitrogen cycle? N-fixation:
N2 = NH3 (ammonia) = NH4+ (ammonium)
or
NH3 = NO3- (nitrate)
140
N-fixation by humans GREATER
than ALL natural fixation !!!!! why?
- more N as ammonium or nitrate
available to plants
141
What is the result for plant communities????
-higher productivity
-sometimes = lower species richness= favouring dominant competitors
142
nitification
the final process in the nitrogen cycle, which converts ammonium to nitrite (NO2) , and then from nitrite to nitrate (NO3-)
143
The phosphorus cycle:
-no gas phase
major source of P = rocks
144
weathering:
carbonic acid in rainwater + organic acids produced by decomposition of plant litter react with minerals in the bedrock and release elements
145
How does human activity affect the phosphorus cycle?
-added phosphates to detergents
- fertilizer
-ending up in streams, rivers, lakes
-caused ENTROPHICATION
146
EUTROPHICATION:
: an increase in the productivity of aquatic ecosystems
more N + P = more algae growth = increase algae dying = increase bacteria that eat deade algae (respiring) = decrease in O2 = DEAD ZONE
147
mineraliazation
the process of breaking down organic compounds into inorganic compounds
148
denitrification
the process of converting nitrates into nitrogen gas
149
cultural eutophication
an increase in the productivity of aquatic ecosystems caused by human activities
150
watershed
an area of land that drains into a single stream or river
151
The Breakdown of Organic matter
-weathering is very important and very slow
therefore, really important to recycle nutrients in dead organic matter
- mainly fungus, bacteria, invertebrates
152
The Breakdown of Organic matter
(in terrestrial ecosystems) Main processes:
1) Soluble minerals and small organic compounds leach out of detritus
-ex salts, sugars, amino acids
(2) large detritivores consume organic matter
- millipedes, wood lice, earthworms
(3) fungi break down woody components (can penetrate tissues)
(4) bacteria decompose almost everything (even LIGNIN!)
- about 90% of plant matter produced each year is NOT consumed by herbivores
153
The rate of decomposition depends on:
1) environmental conditions
-temp - hotter = faster chemical rxn
-precipitaion- more water = more leaching
2) the chemical composition of the material
- more ligin = slower decomp
3) what decomposers are present!
- earthworms
154
tropical forest:
70% decomposition of Inga tree leaves in 250 days
155
boreal forest:
70% decomposition of aspen leaves in 12 YEARS !!!!
156
157
Habitat heterogeneity
variety in habitat conditions
ex- soil types, topography, height of vegatation, age of forest, vegeatation types
region 1 = 16 vegatation types
region 2 = 5 vegatation types
region 1 has more varity = more heterogeneity
158
Why does it promote higher species richness?
-different species are adapted to different habitat conditions (niche) therefore lots of different habitat conditions - lots of different speices
159
Often, habitat heterogeneity is caused by
things that happened in the past
160
Legacy effects:
when something that happened in the past is still affecting ecological communities
can happen naturally or by humans
161
example of legacy effect
Fire history: different regions last burned at different times = forests of different ages
162
landscape ecology
the field of study that considers the spatial arrangement of habitats at different scales and examines how they influence individuals, populations, communities, and ecosystems
163
Levels of species diversity:
Researchers counted # of bird species at 206
sites in Boreal Forest
- at each site, on average, they found 29 species = local species richness OR alpha diversity
- total for all sites together = 134
species = regional species richness or gamma diversity
164
Gamma diversity or regional species richness
ALL the species that live in the region
the number or species in all of the habitats that comprise a large geographic area
165
local species richness OR alpha diversity
the subset of all those species that can live at that particular site
the number of species in relatively small area of homogeneous habitat, such as a stream
166
Beta diversity:
number of species that differ between 2 habitats (number not shared)
167
regional species pool
the collection of species that occurs within a region
168
species sorting
the process of sorting species in the regional pool among localities according to their adaptions and interactions
169
species- area curve
a graphical relationship in which increases in area (A) are associated with increases in the number of species (s)
170
Why do we find this consistent species-area relationship? Potential explanations:
(1) Larger areas tend to have greater habitat heterogeneity
-=more niches = more species
(2) Smaller areas have smaller populations, and smaller populations
=higher extinction rate
(3) sampling phenomenon
171
stepping stones
small intervening habitat patches that dispersing organisms can use to move between large favourable habitats
172
equilibrium theory of island biogeography
a theory stating that the number of species on an island reflects a balance between the colonization of new species and the extinction of existing species
173
Habitat fragmentation:
1.The total amount of habitat goes… down
2.The number of patches of habitat goes… up
3.The total length of edges goes… up
4.The distance between patches goes… up = increased isolation
174
More edges =
more ecotones
ecotones often support a higher number of species
175
Conditions at forest edges…
more sun can get in, therefore… more light, warmer, less mositure
176
IS FRAGMENTATION BAD???
1) LOTS of evidence – strong species-area relationship, more habitat = more species
2) DEBATEABLE – if choosing between one patch and several patches that add up to the same total amount of habitat, 1 patch is not always the best option
177
continential drift
the movement of landmasses across the surface of earth
178
PERFECT NESTEDNESS
saving the most species to save biodiversity
179
NOT PERFECTLY NESTED
When the many small has more different species than the one big region
180
S =
= equilibrium number of species
181
largest S =
large islands that are close to the mainland
182
Patterns of species richness in North America:
On a global scale, biodiversity is highest near the equator and declines toward the poles
183
why would canada have more biodiversity?
-canada was glaciated in the past
-each time glaciers retreat, plants have to recolonize
-each time glacier advances - disperse or go extinct
-cape floristic region = stable climate
184
Where should we protect biodiversity?
assumption: we cannot protect EVERYTHING EVERYWHERE
- not enough $$$
- need some land for cities, farms, mines
Therefore, we need to prioritize.
185
Where should we protect biodiversity? Options:
- places that have the most total number of species
- places that have the most endemic species
- places that have the most endemic species and highest degree of threats
186
BIODIVERSITY ‘HOTSPOTS’:
regions with at least 1,500 endemic plant species AND at least 70% loss of habitat
187
BUT Canada is important for other reasons:
1 in intact wilderness
2 in freshwater
#2 in area marine shelf
#2 in soil carbon storage
188
Why do we value biodiversity?
(1) Instrumental value
(2) Intrinsic value
189
Instrumental value
- different species provide products (lumber, food, medicine), services (flood regulation, water purification), cultural benefits (recreation, arts)
a focus on the economic value a species can provide
190
(2) Intrinsic value
species are inherently valuable, they deserve to exist just as we do, and we have a moral obligation to protect them – even if they provide NO benefit to us
a focus on the inherent value of a species, not tied to any economic benefit
191
How many species live on planet
Earth???
- many not described yet
-estimated total 3-100 million
-most scientists estimate ~10 million
192
provisioning services
benefits of biodiversity that humans use, including lumber, fur, meats, water, crops, fibre
193
regulating services
benefits of biodiversity that include climate regulation, flood control, and water purification
194
cultural services
benefits of biodiversity that provide aesthetic, spiritual, or recreational value
195
supporting services
benefits of biodiversity that allow ecosystems to exist, such as primary production, soil formation, and nutrient cycling
196
Extinction:
has been occurring throughout the history of life on Earth
197
Mass extinction event =
least 75% of all existing species go extinct within a 2 million year period
-most recent (dinos)
-after mass extinctions, more species evolve
198
It can be hard to assess how a species is doing
1. it has to be known/named
2. it has to be studied well enough over a long enough time period to determine whether it is declining or not
- therefore takes time, expertise and money
199
IUCN =
international union for the conservation of nature
-redlist
- founded in 1948
- gathers data on the status of species
200
Biodiversity includes…
diversity of SPECIES
GENETIC diversity
201
GENETIC diversity = diversity within species
provides ability for a species to adapt to different conditions
- ex: new disease
202
The biggest cause of recent losses of biodiversity =
HUMANS
203
The biggest cause of recent losses
of biodiversity = HUMAN
(1) HABITAT LOSS
(2) Overharvesting
(3) INTRODUCED SPECIES
(4) POLLUTION
(5) GLOBAL CLIMATE CHANGE
204
(1) HABITAT LOSS
35% of global land area now used for
crops or pasture
- 10 million hectares of tropical forest is
logged every year 1/6 of alberta
205
Even if a remaining piece of oldgrowth forest is protected from logging, some species that live in it may still go extinct. WHY?
-small area supports smaller populations
-smaller populations are more susceptible to extraction
-time lags
206
(3) INTRODUCED SPECIES
domestic cats and animals
207
(5) GLOBAL CLIMATE CHANGE
- increasing temperature
- has not caused widespread extinction YET
- but: species will have to shift their distributions
208
BIOMAGNIFICATION:
the process by which the concentration of a contaminant increases as it moves up the food chain
209
biotic homogenization
the process by which unique species compositions originally found in different regions slower becomes more similar due to the movement of people, cargo, and species
210
What can be done???
1 major thing is HABITAT PROTECTION
211
goal:
protect enough habitat to support the minimum viable population (MVP)
= the smallest population size that will allow a species to persist even with environmental variation
212
