Environmental Flashcards
uk warming stripes
evidence that its getting warmer
global changes in 2020/21/22
-floods
-droughst and wildfires
-extreme temps
heat domes
high pressure pushing warm air down like an oven
wacky jet stream
-ice on electrical systems
drought and wildfires
-Wildfires becoming more frequent, longer lasting
-Difficult to control
-Impact on society, infrastructure, wildlife and biodiversity, atmospheric chemistry
costs associated with climate change
Cost $150 billion in US for 2022
For context:
Global Military Expenditure in 2020 nearly 2$ trillion
Global fossil fuel subsidies, although 40% down in 2019, still $180 billion in 2020
Anthropocene syndrome
a complex of environmental degradation, biological annihilation in the form of species losses, non-communicable disease epidemics, climate change, and increasing incivility in public and professional discourse. Image: Susan Prescott.
human influence on the earth system affects infrastructure and economy jellyfish
-The Nomura jellyfish invasion has plagued Japanese fishermen—and probably stems from pollution in China’s Yangtze River
environmental justice
disproportionately affects communities of colour and low-income communities
-(toxic waste landfill in black community)
key research questions
Increased population leads to higher demand for food, leading to more pressure on environmental systems
Associated environmental impacts
Unsustainable use of natural resources
Habitat destruction/pollution
Loss of biodiversity
Threats to global systems
Climate
Habitability
what is environmental stability
The United Nations (UN) defines sustainability simply as “meeting the needs of the present without compromising the ability of future generations to meet their own needs.”
It asks us to consider two things; first, what are ‘needs?’ And secondly, what is life beyond ourselves?”
When looking at life beyond the present, it becomes clear that environmental sustainability involves a level of selflessness to ensure that the people of the future are also being considered
natural capital
World’s stocks of natural assets which include geology, soil, air, water and all living things
It is from this Natural Capital that humans derive a wide range of goods and services which make human life possible.
These are often delivered by ecosystems, which has led to them being called ecosystem goods and services.
ecosystem
A community of plants, animals and micro- organisms, along with their environment, that function together as a unit. An ecosystem can be as large as a rain forest or as small as a rotting log.
millenium ecosyystem assessment
Provided information about the current state of the world’s ecosystems
ecosystem services delivered by trees/forests
supporting
supporting
-nutrient cycling
-soil formation
-water cycling
-photosynthesis
Ecosystem services delivered by trees/forests
* Provisioning
– Wild food – berries, mushrooms,
game, honey
– Timber – fuel, construction, furniture, matches
– Medicines – e.g. aspirin (willow), taxane (yew – anti-cancer)
– In USA forest ecosystems provide water – as much as 65% run off comes from forests (excluding Alaska)
Ecosystem services delivered by trees/forests
* Regulating
– Large scale clearing can alter rainfall patterns and decrease overall amount of
rain.
– Act as sponge and soak up and store water – evens out annual waterflows from forested watersheds.
– Reduce soil erosion – sediment damages roads, harms fish populations, fills ditches.
– Vegetation protects soil from force of rain and roots hold soil in place
– Filter pollutants.
– Trap airborne particulate matter and ozone that can be harmful to humans.
– Can regulate temperature – in an urban setting provide cooling through shading and evapo-transpiration.
– Absorb carbon dioxide, sequester carbon – reduce greenhouse gases.
Ecosystem services delivered by trees/forests
* Cultural
– Recreation
– Inspiration
– Artistic uses of forest
products
biomes =
- Biome - major ecological community, classified according to the predominant vegetation and characterized by adaptations of organisms to that particular environment
- affected by precipitation and air temperature and soil
five major types of biome
– Aquatic
– Grassland – Forest
– Desert
– Tundra
Ecosystem services – not a comprehensive list
Nutrient cycling
* Soil formation
* Photosynthesis
* Climate regulation
* Regulation of water quality and quantity
* Food, fuel
* Genetic resources
* Cultural services
conversion of natural systems for agriculture
No other human activity has had a greater impact on the Earth’s biodiversity than agriculture.
Expansion of agriculture has resulted in significant impacts on global biodiversity:
1. Loss of wild biodiversity and species shifts resulting from conversion of native ecosystems to agroecosystems;
2. Influence of agroecosystem structure and function on agrobiodiversity;
3. Offsite impacts of agricultural practices;
4. Loss of genetic diversity among and within agricultural species
Some other impacts of agricultural systems
- Intensive water use – irrigation, livestock production, other uses
- Impacts on local and global climate – loss of forest releases
carbon, forests influence local climate/precipitation - Loss of soil ‘quality’ and erosion
- Alteration of nutrient cycles
- Desertification
Extent of agriculture
- Cultivated systems cover approximately 24% of Earth’s surface.
- Defined in the Millenium Ecosystem Assessment to be areas in which at least 30% of the landscape is in croplands, shifting cultivation, confined livestock production, or freshwater aquaculture in any particular year.
Cultivated systems
- Between 300,000 to 500,000 plant species exist, 30,000 thought to be edible
- Only 7,000 have been either cultivated or collected as food
- Only 20 species have provided 90% of the world’s food requirements, with wheat, maize and rice accounting for 60% of human diet – plus grass etc. for livestock
- Most are grown as monocultures
- Compared with natural ecosystems, plant diversity is very low (especially as weeds are removed) – impacts on other species
deforestation
- Forests have a big influence on rainfall patterns, water and soil quality and also flood prevention.
- Trees absorb and store carbon dioxide. If forests are cleared, or even disturbed, they release carbon dioxide and other greenhouse gases.
- Majority of the deforestation is linked to meat, soya (a large proportion to feed livestock) and palm oil.
Betsiboka Estuary, Madagascar (nasa.gov)
Forests and biodiversity
- Forests are home to most of the world’s terrestrial biodiversity.
- Forests provide habitats for 80% amphibian species, 75% bird species and 68% mammal species.
- About 60% of all vascular plants are found in tropical forests.
- Mangroves provide breeding grounds and nurseries for numerous species of fish and shellfish and help trap sediments that might otherwise adversely affect seagrass beds and coral reefs, which are habitats for many more marine species.
soil health
- Healthy soil is physically, nutritionally, and biologically balanced, productive, and stable, and can withstand environmental impacts without loss of fertility, structure, and biological activity.
- Soil-based biological processes may become disturbed or altered by factors such as addition of agricultural inputs, improper land cultivation, and irrigation.
soil organisms
- *
Microorganisms (fungi, bacteria, archaea, and viruses)
Fauna (protozoa, annelids, arthropods, nematodes, and molluscs)
Flora (plants and algae)
desertification
- Persistent or irreversible reduction in the capacity of ecosystems to supply ecosystem services for several decades in drylands.
- Direct factors contributing include management and land use, irrational use of water resources, deforestation, overgrazing, and climate related processes.
- Indirect factors include population growth and density, urbanization, politics, governance, economic conditions, technology, and globalization.
- In particular, irrigation agriculture in dry subhumid regions has caused salinization, acidification, and soil erosion.
conversion of terrestrial biomes
- Impossible to estimate accurately extent of different biomes prior to significant human impact
- Can determine “potential” area of biomes based on soil and climatic conditions.
- Figure shows how much of this area estimated to have been converted by 1950, how much was converted between 1950 and 1990, and how much would be converted under the four MA scenarios (low certainty) between 1990 and 2050.
- Most of the conversion of these biomes is to
cultivated systems - agriculture.
The Cerrado vegetation complex
Brazil s second largest source of biodiversity
favourable factors for agriculture in the cerrados
Great extensions of arable lands Appropriate climatic conditions Landscape suitable for mechanization Good physical characteristics of the soils Availability of basic infrastructure
Availability of mineral resources
scale in ecology
- Scale has a major influence on how people conduct ecological studies, interpret results and understand the links between processes operating at different rates.
- All of these factors influence the ability to predict responses to change.
- The ecological patterns and variability observed range from millimetres to across
ocean basins and from seconds to the expanse of evolutionary history. - Patterns apparent at one scale can collapse to noise when viewed from other scales, indicating that perceptions of the importance of different processes vary in a scale- dependent manner.
- Moreover, rather than the environment simply providing an arena within which organisms are born grow and die, many organisms interact with the environment, altering it for both for themselves and for other species.
- Because of these factors, studying ecological systems is far from simple and scale needs to be considered in study design and analysis.
biodiversity definitions
– The diversity of plant and animal life in a particular habitat (or in the
world as a whole)
– The variety of plant and animal life found in an ecosystem and the variation in their genetic makeup
– The variety of life forms, the different plants, animals and micro- organisms, the genes they contain and the ecosystems they form
What do we mean by biodiversity?
All hereditarily based variation at all levels of organisation, from the genes within a single local population or species, to the species composing all or part of a local community, and finally to the communities themselves that compose the living parts of the multifarious ecosystems of the world.
How much diversity is there?
- Approx. 2 million species of animals, plants and fungi described currently – but there may be 5-15 million – a lot of uncertainty!
- We have identified and named a greater proportion of vertebrates and plants than insects and fungi
Megadiversity Countries
- Megadiversity Countries is a term used to refer to the world’s top biodiversity-rich countries.
- 17 countries which have been identified as the most biodiversity-rich countries of the world, with a particular focus on endemic biodiversity.
- Together, the Megadiversity Countries account for at least two thirds of all non-fish vertebrate species and three quarters of all higher plant species.
species
Often defined as ‘a group of organisms that reproduce naturally with one another and create fertile offspring’.
* Some organisms don’t fit this definition.
* Asexual organisms have just one parent, so they do
not reproduce with each other.
* Some organisms reproduce with similar species in
the wild, forming genetic hybrids. E.g. wild polar bear–grizzly bear hybrid found in Canada. “Pizzly” or “grolar” bears, can produce fertile offspring.
* Approximately 25% of plant species and 10% of animal species are known to hybridize to varying degrees.
natural selection
- Natural selection - process through which populations of living organisms adapt and change.
- Individuals in a population are naturally variable. Thus some individuals will have traits better suited to their particular environment than others.
- Individuals with traits that give them an advantage are more likely to survive and reproduce. Over time, the advantageous traits become more common in the population.
- Natural selection can lead to speciation.
speciation
Speciation occurs when a group within a species separates from other members of its species and develops its own unique characteristics.
plant-pollinator interactions
- Interactions are generalised i.e. few where one species of plant depends on one species on animal
- Vary through time and space
- Lavandula latifolia in Southern Spain – visited by at least 85 species of dipteran, hymenopteran, and lepidopteran pollinators - insects vary in quality as pollinators
Brassicaceae
Mustard family (Brassicaceae or Cruciferae) consists of 338 genera and approximately 3,700 species.
* Very important to agriculture and the environment, accounting for approximately 10% of the world’s vegetable crop produce and serving as a major source of edible oil and biofuel.
Biodiversity and medicine
Bark extract used for centuries to relieve pain
* Salicylic acid synthesised in 1850s – but damaging to mucous
membranes
* In 1893, Bayer Company obtained a patent on acetylsalicylic acid
biodiversity and medicine
- Discovery of penicillin attributed to Alexander Fleming in 1928. He showed that, if Penicillium notatum was grown in the appropriate substrate, it would exude a substance with antibiotic properties, which he called penicillin.
- Can be synthesised (1957) - opened the way to the development of particular penicillins to combat particular bacteria.
- By the early 1960’s, researchers started producing hundreds of kinds of experimental penicillin.
What causes changes in biodiversity?
- Habitat change/destruction
- Invasive species *
Pollution - Climate change
Habitat fragmentation
- Populations become small and isolated
- Increased genetic drift, inbreeding depression and increased risk of extinction if population very small
- Genetic drift: change in the relative frequency with which an allele occurs in a population due to random variation
Impact of urbanisation
The changes in plants and animals included alterations in body sizes, shifts in behavioural patterns and adjustments in reproduction.
fishing issues
Destructive fishing is a factor in shallower waters
– bottom trawling homogenizes three- dimensional benthic habitats
– dramatically reduces biodiversity.
invasive species effects on fish
- Introductions of new species can cause abrupt changes in populations in coastal ecosystems.
- E.g. introduction of the invasive, carnivorous ctenophore Mnemiopsis leidyi (a jellyfish-like animal) in the Black Sea
- Eats eggs and larvae of fish.
- Caused rapid loss of 26 major fisheries species and has been implicated (along with other factors) in the continued growth of the oxygen-deprived “dead” zone.
- The species was subsequently introduced into the Caspian and Aral Seas, where it had similar impacts.
pollution
- Nutrients
- Pesticides
- Other pollutants e.g. mining and industrial waste
regulation of pests and disease
- Predators consume crop pests e.g. ladybirds, hover fly larvae consume aphids, frogs consume a range of invertebrates
- In many agricultural areas, pest control provided by natural enemies has been replaced by the use of pesticides – such pesticide use has itself degraded the capacity of agro-ecosystems to provide pest control
climate change
- Climate change likely to affect the distribution of many species – animals and plants
- Also likely to affect their phenology (e.g. flowering time of plants and emergence time of insects) so that they become de- synchronized
Conservation
- Can focus on species (e.g. pandas) or habitats (e.g. savanna)
- More focus in recent times on habitats
Some ecosystem recovery is now underway – particularly through afforestation and reforestation
BUT - rates of ecosystem conversion remain high or are increasing for specific ecosystems and regions
Biodiversity off-setting
‘Biodiversity offsets are conservation activities that are designed to give biodiversity benefits to compensate for losses - ensuring that when a development damages nature (and this damage cannot be avoided) new, bigger or better nature sites will be created
reconstructing ecosystems - coral reef
Coral reefs
– artificial reefs
– removing coral predators can help build resilience to thermal stress and bleaching prior to their occurrence
Reconstructing ecosystems
*
Tropical rainforest
– One approach is to plant appropriate trees on the periphery of rainforest – birds and bats fly out and drop seeds – leads to gradual re-establishment
– Could be used to ‘join-up’ fragments of rain forest
Reconstructing ecosystems
* Re-wilding Britain
– ‘Rewilding seeks to reinstate natural processes – for example, the free movement of rivers, natural grazing, habitat succession and predation. It is not geared to reach any human-defined optimal point or end state. It goes where nature takes it’
– ‘The reintroduction of missing species may be a necessary part of rewilding where it’s needed to achieve the full range of natural processes and healthy functioning ecosystems’
What are the things about biodiversity that we need to be concerned about now and in the future?
- Will the loss of biodiversity have an impact on the Earth and human well-being?
- Is ‘quantity’ or ‘quality’ important?
- Are there some species that we just can’t afford to lose?
no species lives in isolation community and ecosystem definitions
Community: assemblage of species populations that occur together in space and time.
Ecosystem: the biological community plus the abiotic environment in which it is set.
The community consists of a series of interconnected trophic interactions: a food web
Species within the community can be classified into functional groups according to the way they acquire energy.
Energy flows in a food web from one part of the ecosystem to another (trophic dynamics).
competition predation
They both concern the requirement for individuals to obtain resources for survival, growth and reproduction.
Competition occurs where resources are limited.
Predation concerns acquisition of food by herbivore and carnivore heterotrophs in a food web.
competition
Interaction between organisms in which the fitness of one or both is lowered by the presence of another when they have a shared resource.
Intraspecific competition – between members of the same species.
Interspecific competition – between different species with similar ecological requirements.
Competition may be asymmetric, but in many cases both competitors suffer a fitness reduction.
resources
Biotic or abiotic components of the environment.
Consumed or used by an organism.
Solar radiation, other organisms, water, space.
In real populations, growth is not exponential
-resources are limited which slows population growth
Population regulation involves density dependence:
-Rate of population growth is slowed with increasing population density.
-Population is affected in proportion to its size.
-Density-dependent mortality; density-dependent fecundity.
intraspecific competition can result in an S shaped population curve
1)Population growth of Lactobacillus sakei in nutrient broth.
2)Population of shoots of the annual plant Juncus gerardi in salt marsh.
3)Population of willow trees in an area where myxomatosis disease had prevented rabbit grazing.
inter vs intra competition
The same basic idea of density dependence apply to intra- & inter-specific competition.
Interspecific competition can result in co-existence or exclusion of 1 species population by another, depending on resource availability and conditions.
Again – important for conservation of biodiversity.
two competitions of how species interact via aggression etc…
Interference competition:
-Individuals interact directly, e.g. via aggression
-interfere with foraging, reproduction, or by directly preventing physical establishment.
Exploitation competition:
-Individuals do not interact directly.
-Rather one individual is affected by the amount of resource that remains after it has been exploited by others.
-i.e. consumption of food depletes the amount available to others.
predation
-Consumption of one organism (the prey) by another (the predator).
-The prey is alive when the predator attacks it.
3 types of predators
True predators
-Kill prey straight after attack, consume several or many prey in lifetime.
Grazers
-Consume only part of each prey, not usually lethal, attack several or many prey in lifetime.
Parasites
-Consume only part of prey, may not be lethal, attack one or very few hosts, intimate association.
Predation is not just a transfer of energy
-Predators are agents of mortality and regulate prey populations.
-The prey is a resource and regulates the predator population.
-Results in coupled density dependence : reduces large populations and increases small populations.
-Seen in nature in a few cases: Wolf-moose on Isle Royale, Michigan
ecology
competition, predation and environmental management
Competition and predation combined: apparent competition
By increasing predator abundance, each prey species is indirectly decreasing the abundance of the other prey species.
invasive exotic species
-Non native species accidentally or deliberately introduced to an area outside of its natural range, which establishes and spreads and causes economic, environmental / ecological damage.
-Cause damage because:
-Compete so successfully in new ecosystems that they displace native species.
-Damaging effects through predation.
-Some also transmit pathogens to native species.
Second biggest cause of biodiversity loss.
Characteristics of invasive species
-Tolerate a variety of habitat conditions.
-Grow and reproduce rapidly.
-Compete aggressively for resources (like food, water, and nesting sites).
-Lack natural enemies in the new ecosystem. This allows them to proliferate.
-These things may be linked: lack of natural enemies may allow a species to be more competitive because it is more abundant.
Trying to control invasive species: Classical biological control
-The intentional introduction of an exotic predator as a biological control agent for permanent establishment and long term pest control.
Based on the ‘NATURAL ENEMY RELEASE HYPOTHESIS’.
-An organism invades a new geographic area (usually moved accidentally by people). In so doing, it escapes its “natural enemies”. Its population is no longer controlled and it becomes a pest.
This is a major reason for the success of invasive species.
why use stats in environmental
Describe features of a dataset
Make inferences about a population using sample data
* Estimate parameters (such as means) with a certain level of confidence * Test hypotheses about specific parameters or relationships
Predict future values based on past dat
In 1980, the National Science Foundation funded the first Long-Term Ecological Research (LTER) sites to provide a longer view of ecological systems
LTER sites serve the wider ecological community by:
* Making almost 40 years of sustained observations publicly available,
* Developing and maintaining large-scale experiments,
* Providing long-term context and deep knowledge of place for researchers working on shorter-term projects training in interdisciplinary and collaborative team science
Data =
A collection of observation – measurements made of something
A variable =
Another name for a collection of data. Variable because it is unlikely that the data are all the same.
data types include discrete continuous and categorical =
See Bar Chart for Discrete
* See Histogram for Continuous
a population can be thought as
Every possible object (or entity) from which the sample is selected
* The complete set of all possible measurements that might hypothetically be recorded
* The complete “thing” that you are interested in studying but which can’t be measured in
its entirety.
a measure of spread and variation is confidence intervals =
range of data around the mean, where we expect (within a certain percentage) that the true population mean will be contained.
normal curve
-also known as Gaussian distribution
-negative to positive infinity
-95% of the area under the curve lies within 1.96 SDs
-99% of the area is within 2.58 standard deviations from the mean
if a data set is approximately normal the probability of selecting (at random) an observation that is within 1.96 standard deviations of the mean
is p = 0.95; within 2.58 standard deviations is p = 0.99
stat tests that require normally distributed data
students t test and ANOVA
we can test data for normality
Shapiro-Wilk Test, Kolmogorov-Smirnov Test
NON NORMAL IS SKEWED and you can LOG IT
teh quartile (QQ) plot
-useful and better than histogram to identify data normality and outliers
if NORMAL THEN SHOULD BE STRAIGHT LINE
hypothesis testing process
- Define the Null Hypothesis (No Difference)
- Define the Alternative Hypothesis (There is a Difference) 3. Specify the Alpha Value (typically ⍺=0.05)
- Calculate the Test Statistic
- Compare to the Critical Value
one sample t test
measures the number of standard errors the sample mean is a hypothesised value
A p-value of 0.95% or greater means we can be at least 95% confident that the true (population) mean is not the hypothesized value
two sample t test and f test
Considers the probability that two samples of data do not have the same population mean
An F-test is used to compare the sample variance and see if any difference could be due to chance.
Analysis of variance (ANOVA)
-used to test whether three or more groups of data have teh same population mean
-Considers the variations between groups relative to the variation within groups
non-parametric tests definition
do not begin with fixed assumptions about how the data and the population are distributed (e.g., normal distribution).
-However, if the assumptions (normality) are met it is better to use a parametric test
parametric vs non-parametric
Parametric Tests for Normally-Distributed Data Include: Two-sample t-test
ANOVA
Non–parametric tetsts include: Wilcoxon Rank Sum Test
Kruskil Wallis Test
correlation coefficients =
describe the degree of association between two sets of paired values
Pearsons correlation coefficient (R)
measures the strength of the straight- line relationship of two variables
regression =
a statistical technique that relates a dependent variable to one or more independent (explanatory) variables. This technique can be used to:
* Summarize data
* Make predictions
* Explain what causes what
bivariate regression =
finds a line of best fit to summarise the relationship between two variables.
This line can be used to make predictions for what the Y value would be for a given value of X
The amount of variation in Y that is explained by X
is the R2 – a metric of linear fit from 0-1.
a multiple regression
is when two or more X variables are used to explain the Y variable
The use of multiple regression requires checking for multicollinearity
It is often helpful to standardize the variables so their effects can be compared
The aim of modelling should be to find the minimum adequate model for the purpose of the research question.
exploring spatial relationships
- It is sometimes useful to understand where something is happening.
- This may help explain what is happening and/or why it is happening
- If geographic patterns exist in a dataset, there is reason to believe that the pattern did not arise by chance.
Population growth in an uncrowded environment
Whooping crane (Grus americana) – an endangered species recovering from near extinction.
Breeds in Canada, overwinters in Texas. Protected in 1916.
15 birds alive in 1941.
Showed an exponential increase in numbers on wintering grounds.
During this time, birds are being born and others are dying. Births > deaths.
Population growth in crowded environments: intraspecific competition results in an S-shaped population curve
When the population grows, births > deaths. When it is constant, births = deaths.
Predator prey dynamics can result in coupled oscillations
Predators are agents of mortality and regulate prey populations.
The prey is a resource and regulates the predator population.
Results in coupled density dependence : reduces large populations and increases small populations.
complex predator prey relationships
-effected by biotic and abiotic factors
-competition and predation are density dependent processes and tend to be stabilising for populations over long term
disturbance events
determine population change (very bad weather)
K value
values = differences in successive values in previous column, i.e. deaths in one of the phases
Conservation: the problems of protecting endangered species
Land use change through human activities affects other organisms through loss or degradation of their habitat
Some populations are now restricted to protected areas
How do you decide how large these protected areas must be to keep a population viable?
Conservation: the problems of protecting endangered species
To conserve species, you need to understand the factors that determine their population size.
The number must be large enough to withstand chance variations in
births and deaths
environmental changes
genetic drift
catastrophic events
Minimum viable population (MVP) =
the number of individuals necessary to ensure the long-term survival of a species
a 99 % chance of survival for 1000 years despite the foreseeable effects of demographic and environmental stochasticity and natural catastrophes.
How is the MVP determined?
It depends on the life history of the species and the ability of individuals to disperse among habitat patches
Genetic models suggest that vertebrates with populations of an actual size less than 1000 are highly vulnerable to extinction
For species that have large fluctuations in population size (many invertebrates and annual plants), the estimated MVP is 10,000
Understanding of Minimum Viable Population Size and Carrying Capacity
Once the MVP for a species has been determined, the area needed to support the population must be estimated
This is the MINIMUM DYNAMIC AREA (MDA)
Need to understand
carrying capacity of the habitat
the home range size of individuals, family groups, or colonies
Gives an estimate of the area requirement per individual
migration is really important for population dynamics
Migration is a vital factor that influences abundance.
Landscapes are usually heterogeneous: areas of suitable habitat are interspersed between unsuitable areas.
Many populations are fragmented and patchy. Dispersal between patches affects the overall population dynamics.
Key features are:
‘habitable site’ (size, number, life span)
‘dispersal distance’.
A patch =
a relatively homogeneous area of suitable habitat that differs from its surroundings.
the meta population concept
Combines patchiness and dispersal.
A metapopulation consists of a collection of sub-populations.
Each sub-population has a chance of going extinct and appearing again through colonization.
Metapopulation dynamics is a balance between extinction and colonisation.
Conservation and the metapopulation concept land use change
Land use change – especially intensive farming – has resulted in large scale loss of habitats for most species plant and animal species and is driving the current mass extinction.
lynx metapopulation
In 1900 it was found in much of Spain and Portugal.
Now restricted to Iberian Peninsula.
World population is below 1000 individuals distributed among 9 spatially and genetically isolated populations.
Its existence depends upon maintaining genetic exchange among the local populations.
ecological communities
Determinants of community structure.
Keystone species are really important for determining community structure.
Apex predators are often keystone species. The affect community composition through a ‘trophic cascade’.
how does a community form
ecological succession =
the process of change in the species structure of an ecological community over time.
primary succession
the development of a community on newly exposed substrate. The site has never supported a community before.
Early colonizing pioneer species tolerate the novel conditions and initiate ecological processes.
Later species grow more slowly, but are able to outcompete the colonizers.
Reasonably predictable sequence of species.
secondary succession
the re-colonization of a community after disturbance.
founder controlled communities
Coral reefs: most reef fish are active by day and need hiding places to shelter from predators (sharks) at night.
Suitable territories (with good hiding places) are patchy. When one becomes vacant, individuals of different fish species have an equal chance of occupying it.
All species are good colonists of a gap and equal competitors.
Species equivalent in ability to invade gaps.
using ecological knowledge to protect the environment – some basic ideas.
Understanding succession, meta-populations, patchiness and community structure is important for conservation & sustainable living.
We are undergoing the 6th mass extinction event on Earth:
changes in land and sea use (industrial farming);
direct exploitation of organisms;
climate change;
pollution
invasive alien species.
How to save the planet?
Produce enough food for us and do so in an environmentally sustainable way.
Stop over exploitation of wild organisms.
Put significant areas over to wildlife.
Improve connectivity & join up patches.
Make landscape multifunctional – farming and wildlife together.
‘Joined up’ policies: inclusive, enabling politics, economic reform etc.
Habitat connectivity
Suitable habitat patches need to be connected to allow wildlife to move freely
ecology =
The scientific study of (i) the distribution and abundance of organisms, and the interactions that determine their distribution and abundance; (ii) the relationships between organisms and their environment
community consists of a series of interconnected trophic interactions: a food web
Energy flows in a food web from one part of the ecosystem to another (trophic dynamics).
Energy is fixed and released through metabolic processes that drive all the living components of the biosphere.
Species within the community can be classified into functional groups according to the way they acquire energy.
endosymbiosis and sunlight and photosynthesis
The first ecosystems probably comprised unicellular chemosynthetic bacteria releasing energy from inorganic molecules.
But since 3 billion years ago, oxygenic photosynthetic organisms have supported the majority of ecological communities that have developed on Earth.
Energy enters the biosphere mainly as sunlight.
Radiant energy on earth = 5 x 1010 J m-2 per year
Both chemosynthetic and photosynthetic organisms are autotrophs (literally ‘self nourishers’).
primary producers
Photosynthetic organisms utilize the radiant energy of sunlight, and water as an electron source, to synthesize carbohydrates.
6CO2 + 6H2O ——> C6H12O6 + 6O2
carbon dioxide water radiant energy glucose oxygen
Only 44% of light is at wavelengths used by photosynthetic pigments. Typically, around 2% of the energy that strikes the leaf surface is fixed in sugars. Nevertheless, the biomass of photoautotrophs is the principal source of energy for all major ecosystems.
gross primary productivity (GPP)
the total amount of energy assimilated from photosynthesis
respiration (R)
the energy used in metabolism
net primary productivity (NPP)
the energy available for growth or reproduction after that used in respiration
NPP formula
NPP = GPP - R
Temperature, water and nutrients control primary production in terrestrial ecosystems
measures of NPP plotted against precipitation and temp prove that
Evapotranspiration and productivity: the wetter the better (oo-err, sounds a bit rude)
A combination of warm temperatures and good water supply for transpiration give higher primary productivity.
TRANSPIRATION: the evaporation of water from plants while they are photosynthesizing.
Actual EVAPOTRANSPIRATIONn is the combined value of land surface evaporation and transpiration from plants. It reflects the demand and supply of water.
The demand is a function of incoming radiation and temperature.
The supply is a function of precipitation.
Temperature, light and nutrients control primary production in aquatic ecosystems
Photosynthetic organisms can only grow when GPP > R.
Compensation point: light intensity is such that GPP = R.
The most productive waters are coastal:
Shallow waters allow greater transport of nutrients from bottom sediments to surface waters, aided by wave action and tides.
Coastal waters receive larger nutrient inputs from rivers.
Energy moves from primary producers to
the rest of the food chain
energy wasted from primary
metabolism heat and waste
The efficiencies of these transformations are expressed as percentages.
Assimilation efficiency = Energy assimilated (A)/Energy consumed (C)
Production efficiency = Energy fixed in tissues (P)/Energy consumed (C)
Growth efficiency = Energy fixed in tissues (P)/Energy assimilated (A)
Production efficiencies of animal groups
Endotherms have lower efficiencies because they have higher metabolic costs, associated with maintaining a constant body temperature.
Energy flow through the food chain (N American grassland ecosystem)
a lot of energy passes to decomposer community