2.4-2.5 (Kognity only) Flashcards
K Strategists
Produce very few offspring, increase the quality of them by investing in parental care. Quality means first for purpose. Survive long enough to reproduce
r strategists
Focus on the increased quantity of offspring at the expense of quantity. Little to no parental car. Survival is low but high numbers of offspring ensure survival
r strategists are beneficial in
Unstable, unpredictable environments. Early days of succession are unstable creating harsh environments thus they are more common in pioneer stages
K strategists are beneficial in
Stable environments. Succession stability increases with times so K strategists are more common in the climax community
Survivorship curve
Shows the number of individuals in a population of 1000 that are expected to survive a certain age. The Y axis is a logarithmic scale with 1000 individuals. X axis is the organisms relative age as a percentage of max lifespan
Type I survivorship curve
Indicative of the K-selected species. The curve starts out very flat showing a high survival rate in early life. This long life expectance causes the line to have a sharp drop at the end as the mortality increases dramatically.
Type II survivorship curve
the middle ground with a more or less constant mortality rate throughout the organisms life. That is they are as likely to die at birth as they are at old age.
Type III survivorship curve
typical of the r-selected species. The curve drops sharply immediately showing very low survival rates after birth. Very few individuals make it into later life.
Biome
Collection of ecosystems classified according to their predominant vegetation. They share similar climatic conditions and organisms that have adaptions to the environment
Biomes are one level down from
The biosphere, and cover large areas of the earth’s surface. Each having abiotic and limiting factors, productivity, biodiversity, and numerous ecosystems
5 categories of biomes
Aquatic Forest (tropical, temperate, boreal, taiga), Grassland (savanna and temperate), Desert (hot, coastal, cold), Tundra (Arctic, Alpine)
Aquatic biomes are:
Freshwater or marine
Marine biome
Deep ocean, coral reef, estuaries, mangrove swamps
Freshwater biome
Ponds, lakes, streams, rivers, wetlands such as bogs and swamps
Canopy layer
Dense layer made of taller deciduous of a tree or shrub - maple oak, birch, or gums depending on location. Not many animals live in the canopy because conditions are harsh. Exposed to winds and airborne predators
Ground layer
Mosses Lichens and liverworts
Herb layer
Grasses, ferns, lichens, and wildflowers, with snakes, mice, amphibians, and insects
Shrub layer
The canopy allows sunlight to penetrate so smaller trees, saplings, and low growing woody plants such as azaleas and blackberries are found here. Animals are frequent and protected by airborne attack by the canopy, high enough above ground to avoid forest floor predators. Animals found here are dependent on the location but include numerous birds, insects, and other small mammals
The drier climates (desert and tundra)
Have more extreme temperature ranges and both show maximum temperatures around June to September
Tropical rainforests show
No seasonal variations in temperature
Savanna has
Lower temperatures when deserts and tundra show the highest
Precipitation in biomes
Not all precipitation will be available to vegetation. In the tundra, precipitation is snow and falls and freezes until summer thaw. In hot deserts it might not make the ground, evaporating before reaching the surface. If it does make the ground, temperatures are high enough to cause evaporation of soil and surface water
Precipitation evaporation (P/E)
Addresses how much water stress there is within a biome
P/E above 1
Waterlogged or heavy leached soils
P/E below 1
Indicative of water shortages (deserts). Rainfall may soak into the soil but high evaporation rains will draw it back to the surface, causing salinisation
P/E of 1
Good soil moisture leading to fertile soil and good water available to plants
Net primary productivity in Biomes
High at the equator due to ideal growing conditions of high temperatures with plentiful sun/water. NPP drops towards the poles as growing conditions become less favourable. Deserts are close to the equator but have low NPP due to water scarcity despite good temperature and sunlight. Grasslands are lower due to seasonal rainfall and a dry season. NPP is low at the poles due to lack of water and sun
Succession
A change over time, changes in the plant community cause changes in the physical environment. May occur alone (on fresh lava the whole area will go through succession through time) - but on a sand dune it is seen with zonation
Sand dunes
The area closest to the sea is at the beginning of succession, as you move away from the sea the sand dunes succession has progressed until you move into grass and onto woodland. The physical conditions change so zonation appears
Zonation
A spatial change in response to changing conditions. Occurs without succession (rocky shore demonstrates it due to tidal changes and not succession). Plant communities adapt to the different environmental conditions. Change in vegetation community along an environmental gradient
Zonation changes may occur
By change in altitude, depth of water, tidal levels, distance from sure etc. They are spatial and determined by changes in abiotic factors. It is also triggered by changes in climatic conditions with increased altitude
Changes up a mountain may include (zonation)
Shortening of the growing season by lower temperatures and longer periods of freezing, more precipitation and a change of rain to snow with longer periods of snow coverage, higher rates of isolation, strong winds for longer periods of time
As distance from the shore increases
The vegetation communities change with changing conditions
Moving away from the sea (sand dunes)
Soil changes: depth and humus content increase, pH decreases moving from alkaline to neutral, moisture holding capacity improves, sea spray and winds decrease
Succession is the
Predictable change in a vegetation community over time. It starts with a pioneer community then transitions through intermediate communities to the final climax community. The ecological community changes composition. Some species starts this process as dominant species but die out replaced by an alternative dominant species. Through time vegetation becomes taller and the ecosystem more complex
Types of succession
Hydrosere, Halosere, Psammosere, lithosere, xerosere
Xerosere
Succession in dry areas
Halosere
Succession in salt water marches
Lithosere
Succession starting from bare rock. Seen on lava flows
Psammosere
Along sand dunes, stabilises them and stops them from shifting
Hydrosere
In a body of freshwater, small lakes may disappear and be replaced by plant communities
Factors can be measured
At a particular point in time, changing over space, changing through time
Sampling
“A process used in statistical analysis in which a predetermined number of observations will be taken from a larger population”
Three main sampling techniques in ESS
Random, systematic, stratified
Sampling in ESS
Establishes when and where to measure biotic and abiotic factors and/or how they change. Spatially they may change along an environmental gradient, temporal changes can be measured through succession, and abiotic and biotic factors can be measured as part of an EIA
Random sampling strategies
Pair of numbers as a point, random areas as a square with two numbers in the bottom left corner, random lines by generating two pairs of numbers and joining them
Advantages Random Sampling
Unbiased, suitable for large populations
Disadvantages Random sampling
You may not have access to some sample points, in larger areas the sample points may miss some places
Systematic sample
Choosing a number (n) eg: every 5 people, every 30 minutes, every metre
Advantages systematic
Easier than random with no need for a grid, coverage of the whole area achieved
Disadvantages systematic
May be biased as places have different chance of selection, patterns may be missed or areas exaggerated
Stratified sampling
When the population contains subjects eg: 30% under 21, 50% between 22-17. It should have the same proportions in each age group. It does not stand alone and is combined with one of the other two to select areas
Advantages stratified
Flexible (used in many situations as it combines with the other methods), good for comparing subsets, representative of the population so long as proportions are known
Disadvantages stratified
You must know the size of the subsets for accuracy
Quadrat
Plot which identifies an area you wish to study, the size depends on the organisms being studied. They are used to study plants and non-motile animals or ones that do not move mist. They assess the number or individuals or the percentage frequency
Percentage frequency
How often a particular species appears in an area. Best done with a gridded quadrat, and counting squares. You can take a minimum number, calculate the mean, then extrapolate for the whole study area
Number of individuals
..of a species in the quadrat. Easy to identify, flowers, trees, and slow moving animals
Population density
Useful once you know the number of individuals in an area if the quadrat is 1x1 and there are 30 species then it is 30 species m^-2. When linear dimensions double, area is quadrupled
Quadrat advantages
Quick and easy, accurate with large species, good comparisons over time or space
Quadrat disadvantages
Difficult with small species, inaccurate with things like grass which propagate under-ground, my miss some species in layer vegetation, must identify species accurately, species may look different in different life stages
Transects
Line or belt can be combined with sampling methods
Line transects
Line is placed according to a sampling strategy and the vegetation that touches the line is recorded at intervals
Belt transects
Use of a quadrat as a belt of sampling. Once the line of the transects is determined, the quadrat creates a belt. Recordings are continuous or interrupted
Turbidity can be measured using a
Secchi disk - black and white mounted on a pole . It is simple, cheap and easy but not all people may have the same visual opinion or be able to go deep enough
Flow velocity can be measured with
A flow meter. When the impeller placed in the water the speed it rotates tells you the speed in m/s at which the rivers if flowing. Repeat 5 times and calculate the mean. They are accurate and can be used at various depths but they can be expensive and mixes water with electricity.
Alternative to a flow meter
A float or Pooh stick is an alternative to time how long it takes to cover a set distance. However, this is not very accurate and can only be taken at the surface although it needs limited supplies
Wind speed is measured with an
Anemometer. Digital ones can be read off of. They may be expensive but no calculations other than the mean of results is required, making it quick and simple
Slope angle can be measured using
A clinometer, which can be made with a protractor, swing, and weight. They are not very accurate
Motile organisms
Mobile. They can be measured indirectly or directly with capturing, traps, Nets, pitfall traps, kick sampling, aerial photography, lincoln index
Species diversity can be measured with a…
Kite diagram, which shows the spatial changes in species along a transects
Tricecular model
A transfer of heat through the atmosphere through the Hadley, Ferrel, and polar cells
Polar cell
Air that moves from the ferrel cell to the polar cell rises and continues moving towards the pole. As air cools in descents creating a high pressure region and some of the air moves back towards the equator forming the polar fringe that meet the Ferrel cell at about 60° N or S
Ferrel cell
As the air moves from the Hadley cell to the poles, it enters the Ferrel cell where it picks up moisture as it crosses the sea. At about 60° N or S the warm air meets the cold called the polar front and is forced upwards creating s region of low pressure associated with high rainfall. The rising air is divided with some moving back to the equator and the rest continuing toward the pole
Hadley cell
As air is heated at the equator, it rises and cools with altitude which stops it rising further. As the air moves towards the pole it is deflected towards the right in the northern hemisphere and towards the left in the Southern Hemisphere. The air becomes cooler and denser leading it to falling about 30° N Or S of the Equator. Some is transferred back to the equator replacing rising air and some countries on its journey towards the pole. The divergence of descending air leads to a subtropical high pressure region
Minimum number of quadrat samples to be taken
5
ACFOR scale
Abundant (50), Common (25-50), Frequent (12-25), Occasional (612), Rare (<6), Absent (0)
Probes
Can be used with a reliable data logger to take measurements of several abiotic factors including salinity, pH, temperature, dissolved oxygen, soil moisture, mineral content, and light intensity. All of which can be measured ove time using digital probes / data loggers. Measurement should have controlled and constant factors. 5 measurements are ideal
Advantages of Probes
Quick, accurate, easy to use, can show continuous readings over a period of time when attached to a data logger
Disadvantages of Probes
May be expensive, can break down and give false readings without you knowing
Dichotomous key
Identifies organisms by comparing them with a series of yes or no questions based on the physical characteristics if an organism. They are only things you can see, with very specific language.
Advantages Dichotomous key
Easy to use and construct
Disadvantages Dichotomous key
Parts of the organism may be damaged - lost a tail / leg, some organisms can look very different at different stages in their life cycle, may require some prior knowledge of terminology such as antenna, dorsoventral etc
Lincoln index
Indirect method by which the size of an animal population can be estimated - also te capture/mark/release/recapture method
Assumptions of the lincoln index
Animals are just as easily caught (some might be easier than others creating bias), enough time is allowed for the mixing of animals, population is closed (no immigration or emigration), proportions of marked and unmarked animals
Problems with the lincoln index
Capturing the animals may injure them or alter their behaviour, marks may rub off, marks may make the animal sore or less attractive to predators, some animals may become trap happy or trap shy causing over or under estimation
Kite diagram
Show spatial changes in species along a transects to show changes in species diversity. The width of the bars show how many species were found at the location, the bars will disappear if they are missing
Capturing animals advantages
Non-lethal methods, simple and require little equipment
Capturing animals disadvantages
Careless handling results in the death of organisms, capturing organisms causes stress, methods are only suitable for small, non aggressive animals
Traps
Usually baited and left for up to 12hrs or overnight, checked regularly so the animal does not die of thirst or hunger or is stressed. The main issue is that animals may become trap happy and return to the trap for food and a secure bed
Nets
Best for birds bats and fish, they must be cleared immediately as animals become more stressed. Depending on the net it can result in injury. Sweep nets are used for flying insects and stream invertebrates. This is simple bit can be easy to miss insects in dense vegetation and miss some when identifying and counting
Kick sampling
For stream invertebrates, sediments in the bottom of the water are kicked and and moved slowly towards the net, then they can be released after identification in a tray with water. The main issue is if testing sites are too close together so some drift from one area to another, Also stirring up the sediment reduces water clarity
Pitfall traps
Catches small animals, a container in the ground where an organism can fall. Food and bedding are added with a cover to keep rain and sun out. Good for smaller organisms (insects, venomous organisms)
Aerial photography
Investigates larger animals living in open grassland environments. Useful to estimate the number of large herbivores and carnivores such as horses, buffalos, lions etc. It is no use for animals living in a dense forest. Can take place in a small or large area and a grid can be added to the image and a sample of squares chosen through sampling. Then counted in at least 5 squares before finding the mean
Aerial photography advantages
Can be used for large areas and large animals, can be used for carnivores
Aerial photography disadvantages
Expensive to commission, animals may move and appear in two squares, animals may be hidden by trees, young animals may be missed being hidden by their mother
Biomass
Measured as Dry weight which is necessary because the water content of different organisms can vary enormously. You can only measure biomass of vegetation as it is not possible within animals unless they are killed which is not ethical. It is possible to capture animals and weight them bit this is inaccurate due to the variability of water content
Advantages of measuring biomass
You can extrapolate from a small sample and get some idea of the amount of biomass in the trophic
Disadvantages of measuring biomass
Highly destructive as vegetation is harvested and dried, does not take account of underground mass (roots), not accurate for large vegetation like trees, not possible to get accurate figures for animals in the ecosystem
Secondary productivity
That of animals in an ecosystem. Gross secondary productivity is the food eaten - fecal loss. Net secondary is GSP - respiration. It compares weight of food to weight of fecal loss
Advantages of measuring secondary productivity
You can extrapolate from a small sample and get some idea of the amount of productivity in a trophic level
Disadvantages of measuring secondary productivity
Not accurate as it is not dry weight, can only be used for small non aggressive animals, captivity may stress animals changing levels of productivity
Measuring energy of a trophic level is taken as
Productivity which is more ethical for plants and animals. The method of measurement is partially direct and partially indirect
Net primary productivity formula
Gross primary productivity (GPP) - respiration (R). (Can be measured by subtracting the highest and lowest quadrat)
GPP
The biomass produced before respiration which is not possible to mesure which is what we see in the plant is NPP, left after repair and respiration. GPP, R, and NPP can be estimated for vegetation
Advantages and disadvantages of measuring productivity
Highly unlikely all 3 quadtats are identical in regards to vegetation, it can really only be done once as 3 quadrats are needed
Primary succession occurs in
Areas that have never been occupied by an ecological community (eg: bare rock or sand dunes)
Secondary succession occurs where
There has been natural or anthropogenic (human made) disturbance and the soil is still in place (EG: abandoned fields, deforested areas, flooding, storm damage)
Identifiable characteristics of succession
A directional change as the plant community moves through a series of stages from ozonisation by opine species to the final climatic climax. There is no clear indication between stages and times a vegetation community will possess characteristics of more than one stage
Terrestrial succession
Starts with a bare rock surface. The environment is harsh and variable. Temperatures vary die to exposure and water supply is unreliable. There is no soil but raw material for it to develop
Colonisation
Initiated by pioneer species that adapt to extreme conditions. (r-strategists that are suited to unstable environments of early succession.) They find enough nutrients in the environment to start an ecosystem. Soil forms as weathering breaks down rocks and plants which contribute organic matter to the debris
Establishment
After colonisation, The ecosystem gets going as an ecosystem as opposed to a collection of individual parts. Soil is deep enough to provide niches for invertebrates, they breakdown dead organic matter forming humus to improve water holding capacity. Resource quantity increases, food, shelter, water and habitats develop.
Competition
Stage 3. Throughout succession each species is adapted to a set of abiotic conditions. Pioneer plants have done their job. Making a suitable area to sustain a wider variety of plant life. Abiotic conditions are less extreme. This means complex larger plants invade the area, competing with original species for space, light and nutrients. They provide shelter which changes conditions, pioneers disappear. This environment is more stable
When succession stabilises
Fewer species enter the ecosystem. The rate of new species entering the system falls as trees now shade out the lower levels. K-strategists continue to dominate the ecosystem.
Final stage of succession (Climax community)
In a steady state equilibrium with climate and/or soil. Succession has come as far as it can and will be self-perpetuating as long as prevailing climatic conditions remain.
A lithosphere develops from
Bare rock
Pioneer communities
simple ecosystems with high productivity but limited biodiversity
3 critical aspects of resilience
Latitude, resistance, precariousness
Precariousness
How close the ecosystem is to its limits/tipping point
Resistance
How easily the ecosystem resists change
Latitude
Links to tipping points, the maximum amount of disturbance an ecosystem can tolerate before losing its ability to recover. Once past it will lose ability to recover easily or at all
Secondary succession
Human activities or natural disasters arresting succession part way through / destroying the climatic climax and sending the process back to the beginning.
Stability provides an ecosystem with a
Higher level of resilience
Disturbance
Natural such as floods or anthropogenic (human induced) like deforestation or fracking
Resilience
how well an ecosystem resists damage caused by a disturbance then how well it recovers. It does not mean that the ecosystem will always return to the same state as before but that it has the same function, structures and feedbacks. Therefore there can be more than one stable state.
Succession is controlled by climate and…
Has an impact on the climate. (EG: As vegetation matures it alters light conditions. Plants of the pioneer community have little impact on light availability. As shrubs and trees invade, light changes. Temperatures become even as vegetation shades sunlight, reducing wind speeds. Relative humidity increases with more transpiration surfaces and lower wind speeds)
At the beginning of succession
Low diversity levels as few species can tolerate harsh conditions. Energy and nutrient cycling is limited, food webs and the system in general is simple.
By the end of succession
Vegetation has developed to balance climate. In a forest ecosystem, multiple layers increases the number of available habitats meaning animals, complex food webs and higher species and genetic diversity.
Productivity is
Low at early stages of succession, yet rises quickly due to GPP being low with few produces which means respiration is also low. Pioneer plants grow facet and biomass accumulates quickly giving high NPP
Productivity in the climax community
Production/respiration ratio (P/R) = 1, meaning that the GPP and respiration are balanced. There is no longer a net accumulation of organic matter, energy production and use is balanced.
Soil in the climax community
Mature, lots of organic matter, good structure, drained with good moisture holding capacity, olds water for plant growth and drains excess, organic matter improves nutrient holding capacity so the nutrient cycle is stable and is in balance.
Why are climax communities stable?
Climax communities are stable relating to the system’s complexity. 1955 American ecologist Robert MacArthur noted that with an increase in ecosystem interactions, so did stability. More complex = more stable
Stability of ecosystems (Food)
In a food web with multiple organisms at each trophic level the disappearance of one will not cause great impact. (Depending on food sources available)
