Biodiversity within a community
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- Created by: Hindleyc
- Created on: 23-06-18 20:00
What is biodiversity
A measure of how varied an ecosystem is which can be measured in terms of genes, species or habitat
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Genetic diversity?
Measure of how. many variations there are in the genetic code between individuals of a particular species or between different species
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What is species diversity
Measure of how many different species are present in an area and how many individuals of these species there are
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What is Habitat diversity
Measure of how many different habitats are present in an area
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What is a species
Group of organisms that can share common morphological, physiological and behavioural characteristics, can interbreed and produce fertile offspring
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What is a habitat
Range of physical, biological and environmental factors within which a species can survive
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why measure diversity
Allows comparisons to be made between different areas, in same area at different times
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What is species richness
Number of different types of species in a particular area. greater no. species=richer the area. Important when measuring species diversity of an area
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What doesn't species richness take into account
No. of individuals of particular species
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What is species evenness
Comparison of the size of the population (no. of individuals) of different species within a particular area
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What is species diversity index?
A Quantitative measure of the species diversity of an area- describes relationship b/w no. species in a community and no. individuals in each species
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Species richness
Measure of how many different species there are in a particular area/ community
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Species diversity
The no. of diff species and individuals of those species in an area
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Species evenness
A comparison of the no. of individuals of different species in an area
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What does species Diversity increase with
inc Species richness and inc Species evenness within an area
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What is Simpsons
D= N(N-1)/sum n(n-1)
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What is N
total number of organisms of all species
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What is n
Total number of organisms of a particular species/ each species
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what is D?
Diversity index- p that 2 randomly selected individuals will belong to same species/ group
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Lowest possible value of D
1
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Larger value of D
the greater the diversity
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Why are hedgerows destroyed?
inc productivity of arable land(crops)can lead to decline in these organisms which can be essential for maintaining the balance of the ecosystem - w/o these food webs can fall apart diseases can spread rapidly&crops can become susceptible to Pests
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What are hedgerows home to
Several habitats and support many diff types of insects, birds, small mammals and flowers
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Low biodiversity
Problematic in agriculture - elective breeding creates crops with desirable characteristics - v similar high yields and less waste however h/w lack of genetic diversity can make crop susceptible to pests and diseases
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Monoculture
Used in agriculture growing just one species / variety of crop
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What are biodiversity hotspots?
Regions of the world that have a particularly high level of biodiversity but are threatened with destruction
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Why isn't low biodiversity a cause for concern?
Loss of biodiversity is more important as an ecosystem relies on the interdependence of organisms to maintain stability and loss of species can cause serious unpredictable and possibly irreversible changes
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What can ecosystem disruption ultimately have a significant impact on
Humans
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Ecological impact of farming
Monoculture, selective breeding, huge farms, mechanisation and use of chemical fertilisers and pesticides
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What is apparent
That this intensive farming is damaging the environment and is becoming increasingly difficult to sustain
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What does Monoculture do?
Increases productivity of farmland by growing only best variety of crop allowing more than one crop per year
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What does do?
Simplifies sowing and harvesting of the crops by reducing labour costs
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What is the impact on the environment?
major- using single variety of crop reduces genetic diversity and renders all crops in region susceptible to disease
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Another impact?
Fertilisers required to maintain soil fertility which are expensive and can pollute surrounding ground water due to leaching. Also, pesticides required to keep crops healthy
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Another impact?
Reduces species diversity that has a knock-on effect eg allowing pest species to get out of control- fewer plants due to lack of pollinating insects and loss of species that may be useful to humans
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How to solve?
Return to crop rotating, different crops gown in field each year breaking life cycle of pests (changing hosts) improves soil texture as different crop has diff root structure and increases soil nitrogen
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What do Hedgerows contain?
Large number of different plant and animal species
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What do they do?
Act as corridors allowing animals to move safely between woodlands
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What else do they do?
May reduce pests as some sheltered animals are predators of plant pests, efficient windbreaks, shelter for plants and animals and reduces soil ersosion
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What are they?
Habitat for pollinating insects so removal would decrease population of other local plant species- grants to plant them but take years to mature and develop
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Why are they removed?
No longer needed to contain livestock as larger fields=lower labour as greater mechanisation&provide shelter for pests-reservoir of weeds and disease and reduce space for crops and compete with roots for water and minerals but need to be maintained
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What do fertilisers do?
Add more ions which improves yield
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What are the soluble inorganic ions and what are they like?
NPK that are effective but have undesirable effects on environment
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What are nitrate and ammonium ions like?
V soluble so leached out into rivers and lakes causing eutrophication- v expensive
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Alternative>
use organic fertilisers as have same elements in organic compounds
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How does it work?
Organic compounds can be digested by soil organisms who release inorganic ions that plants can use
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Advantages?
Less soluble compounds.improves soil structure by binding soil particles. released slower as decomposed preventing leaching and lasts longer.Food for soil organisms.improves drainage, aeration
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another adv?
cheap as waste being disposed of - not on landfill where they could have caused uncontrolled leaching
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Disadvantages?
Bulky, less concentrated in minerals so more spread and smelly. may have unwanted materials eg weed deeds, metal and fungal spores
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What are pests?
Organism that damages crops
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Solution?
Chemical (pesticides) Biological (predators) Physical (scarecrow)
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What do they have to be?
Have to be effective against pest but have no effect on crop
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What can pesticides do?
May kill pests or reduce population by slowing growth/ preventing reproduction.
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Where are they required?
Intensive farming- could also control pests carrying human disease therefore save millions humans
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What happens with widespread use and success?
problems- persistences and bioaccumulation and can reduce population of other organisms eg bird
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What is persistence?
how long a pesticides remains active in environment. some chemicals broke down by decomposers in soil-(biodegradable)so not persistent while other cannot be broken down by microbes (non biodegradable)- continue to act for many yrs persistent pesticid
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What is bioaccumulation or biomagnification?
Build up of a chemical through a food chain eg DDT not soluble in water- not excreted easily so remains in fat tissue
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What happens?
Each consumer eats large mass of trophic level below DDT accumulates in fat tissue of animals at top of food chain - high conc in birds toxic effects first noticed in bird
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What is eutrophication?
Effects of nutrients on aquatic ecosystem. in terms of pollution sudden and dramatic inc in nutrients due to human activity which disturbs and destroys for chain
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What is the main cause?
Fertilisers leaching off farm fields into the surrounding water course and sewage both containing dissolved minerals such as nitrates and phosphates which enrich the water
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Biochemical oxygen demand
Rate of oxygen consumption by a sample of water therefore give a good indication of eutrophication. high= lots of organic material= eutrophication
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How can aquatic ecosystems slowly recover?
From high BOD as O2 dissolves from air
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Long term solution ?
Depends on reducing amount of minerals leaching into water- achieved by applying inorganic fertilisers more carefully . By using organic fertilisers. by using low-P detergents and by removing soluble minerals by precipitations in modern sewage plants
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What is Deforestation?
Leads to inc in land for agriculture. growth in human population is inc demand for land for farming- causes local extinction of species of trees
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What does human activity do?
Affect whole ecosystem- conflict b/w need/wish to produce things useful to human in short term and conservation of ecosystem in long term
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What are forests?
Natural climax communities?- High diversity with complex food webs.
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What does it do? why does it need to be saved
Affects mainly tropical rainforests, huge store C and sink for CO2 so destruction may inc conc of co2 by 50%. important in conserving soil nutrients and preventing large- scale erosion in regions of high rainfall, larges gene pool of plant resourc
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What effects?
Affects diversity, loss of trees, removes bases of many food webs, removed habitats of many other species , causes local extinction of other populations or reduction in their size , Reduces no of species presents and no of individuals present
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Other cards in this set
Card 2
Front
Genetic diversity?
Back
Measure of how. many variations there are in the genetic code between individuals of a particular species or between different species
Card 3
Front
What is species diversity
Back
Card 4
Front
What is Habitat diversity
Back
Card 5
Front
What is a species
Back
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