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Populations and Sustainability Explain the significance of limiting factors in determining the final size of a population; Explain the meaning of the term.

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Presentation on theme: "Populations and Sustainability Explain the significance of limiting factors in determining the final size of a population; Explain the meaning of the term."— Presentation transcript:

1 Populations and Sustainability Explain the significance of limiting factors in determining the final size of a population; Explain the meaning of the term carrying capacity; Describe predator–prey relationships and their possible effects on the population sizes of both the predator and the prey; Explain, with examples, the terms interspecific and intraspecific competition; Distinguish between the terms conservation and preservation (HSW6a, 6b); Explain how the management of an ecosystem can provide resources in a sustainable way, with reference to timber production in a temperate country; Explain that conservation is a dynamic process involving management and reclamation; Discuss the economic, social and ethical reasons for conservation of biological resources (HSW6b, 7c); Outline, with examples, the effects of human activities on the animal and plant populations in the Galapagos Islands (HSW6b).

2 Limiting Factors Population size stays stable, but can also rise and fall suddenly Population size is a balance between death rate and rate of reproduction

3 Population Growth Lag Phase: a few individuals acclimatising to their habitat. Growth and reproduction is slow Log Phase: resources are plentiful and conditions are good. Reproduction is greater than mortality. The population increases Carrying Capacity: population has levelled out. The habitat cannot support a larger population. Reproduction rates equal mortality rate. Population stays stable or fluctuates very slightly

4 Why is there a carrying capacity? The habitat has factors which limit the growth of the population size These are called limiting factors Examples: food, water, light, oxygen, nesting sites or shelter, parasites or predators, intensity of competition within and between species

5 Predator Prey Relationships Predator = animal that hunts other animals for food Prey = eaten by predator Predation can act as a limiting factor

6 populations and sustainability Describe predator prey relationship

7 Predator Prey Graph 1. Predator population gets bigger, more prey eaten 2. Prey population decreases- less food for predators 3. Fewer predators survive and they decrease 4. Fewer prey now eaten and numbers increase 5. More prey, so predator numbers increase and the cycle begins again Snowshoe Hare Lynx

8 Predator Prey Graph: Limitations Predators may eat more than one type of prey Predation shown as the main limiting factor and disease/ hunting etc. not taken into account This gives the graph a less defined pattern

9 Populations and Sustainability Explain the significance of limiting factors in determining the final size of a population; Explain the meaning of the term carrying capacity; Describe predator–prey relationships and their possible effects on the population sizes of both the predator and the prey; Explain, with examples, the terms interspecific and intraspecific competition; Distinguish between the terms conservation and preservation (HSW6a, 6b); Explain how the management of an ecosystem can provide resources in a sustainable way, with reference to timber production in a temperate country; Explain that conservation is a dynamic process involving management and reclamation; Discuss the economic, social and ethical reasons for conservation of biological resources (HSW6b, 7c); Outline, with examples, the effects of human activities on the animal and plant populations in the Galapagos Islands (HSW6b).

10 Georgyi Frantsevitch Gause Outline the study on Interspecific competion in paramecium carried out by Gause in 1934

11 Gause Findings 2 species of paramecium grown separately and together Together, competition for food arose, paramecium aurelia more successful than paramecium caudatum which died out Conclusions The more overlap between two species’ niche, the more intense the competition If two species have the same niche, onw would die out in that habitat This is known as the competitive exclusion principle This explains why particular species only grow in particular places

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13 populations and sustainability Explain with examples interspecific and intraspecific competition

14 Competition Occurs when a resource is in short supply As competition increases, reproduction decreases, death rate increases Intraspecific competition: between organisms of the same species e.g. lions Interspecific competition: between organisms of different species e.g. lions and hyenas

15 Is extinction always inevitable? Sometimes, between two species, one just gets smaller and both populations then remain quite constant In the lab other variables are not taken into account e.g. temperature VS. In the lab, T. Castaneum increased their population size, but a change in temperature would mean that T. Confusum was successful T. Castaneum T. Confusum

16 Limiting factors (e.g. space, food, light) create a carrying capacity – maximum population of a species that an environment can support. It is often the factor in the shortest supply Predator-prey cycle: increased prey numbers; predator numbers increase as more food; leads to decrease in prey; predator numbers fall; increase numbers of prey, etc. Intraspecific competition is between individuals of the same species – competing for a mate, food or nest site. Interspecific competition is between individuals of different species – different plant species competing for light/soil/water/nutrients, etc.

17 Populations and Sustainability Explain the significance of limiting factors in determining the final size of a population; Explain the meaning of the term carrying capacity; Describe predator–prey relationships and their possible effects on the population sizes of both the predator and the prey; Explain, with examples, the terms interspecific and intraspecific competition; Distinguish between the terms conservation and preservation (HSW6a, 6b); Explain how the management of an ecosystem can provide resources in a sustainable way, with reference to timber production in a temperate country; Explain that conservation is a dynamic process involving management and reclamation; Discuss the economic, social and ethical reasons for conservation of biological resources (HSW6b, 7c); Outline, with examples, the effects of human activities on the animal and plant populations in the Galapagos Islands (HSW6b).

18 Conservation VS. Preservation Conservation =Management of ecosystems so that the natural resources in them can be used without them running out. E.g. timber management. It can also be reclamation – restoring ecosystems that have been damaged or destroyed. It is dynamic and needs to adapt to constant change Preservation = protecting ecosystems so they are kept exactly as they are. Nothing is removed and they are only used for activities that don’t damage them

19 Sustainable Management and Timber Production Using OCR Biology p , explain how the management of an ecosystem can provide resources in a sustainable way using timber production as an example

20 Sustainable Management and Timber Production Population increasing exponentially More intensive methods used to exploit environmental resources destroying ecosystems, reducing biodiversity and depleting resources Especially apparent in timber industry due to a growing need for wood Sustainable management is possible maintaining biodiversity, sustaining timber companies and also our supply of wood Can be small and large scale

21 Small Scale Timber Production Involves coppicing Harvesting wood keeping tree alive Trunk cut close to ground New shoots form from the cut surface and mature These shoots are eventually cut and again are replaced by more Shoots are used for fencing etc. Pollarding is similar but the trunk is cut higher up so deer cannot eat the new shoots Rotational coppicing where woodland is divided into sections and only cut in the particular section until all have been coppiced, then the cycle begins again- some trees are not coppiced and are known as standards Rotational coppicing is good for biodiversity. The trees never grow enough to block out the light, so succession cannot happen and more species can survive

22 Timber Production management Involves coppicing Harvesting wood keeping tree alive Trunk cut close to ground New shoots form from the cut surface and mature These shoots are eventually cut and again are replaced by more Shoots are used for fencing etc. Pollarding is similar but the trunk is cut higher up so deer cannot eat the new shoots Rotational coppicing where woodland is divided into sections and only cut in the particular section until all have been coppiced, then the cycle begins again- some trees are not coppiced and are known as standards Rotational coppicing is good for biodiversity. The trees never grow enough to block out the light, so succession cannot happen and more species can survive Pollardingcoppicing

23 Large Scale Timber Production Mostly clear felling = cutting down large areas of forest Habitats destroyed, soil minerals reduced and soil left susceptible to erosion. Soil can also run into water and pollutes them Trees remove water from soil and maintain nutrient levels through the carbon and nitrogen cycle Leaving woodland to mature for up to 100 years allows biodiversity to increase however this is not a timescale that would be effective nowadays... However companies nowadays ensure; 1.Trees can be replaced by replanting 2.The biodiversity, mineral and water cycles are maintained 3.Local people must still benefit from the forest Selective cutting involves removing only the largest trees More wood is supplied per tree as pests and pathogens are managed, only well growing trees are planted and they are placed an optimal distance apart to reduce competition

24 Selective cutting involves removing only the largest trees Trees cleared in patches – woodland grows more quickly in smaller areas between bits of existing woodland than in larger open spaces. Less soil erosion will occur. Coppicing and pollarding Only plant native species as they are adapted to the climate New trees attached to a post for support and covered with plastic tubes to stop them being eaten. Planted with optimum space between to reduce competition. More wood is supplied per tree as pests and pathogens are managed.

25 Populations and Sustainability Explain the significance of limiting factors in determining the final size of a population; Explain the meaning of the term carrying capacity; Describe predator–prey relationships and their possible effects on the population sizes of both the predator and the prey; Explain, with examples, the terms interspecific and intraspecific competition; Distinguish between the terms conservation and preservation (HSW6a, 6b); Explain how the management of an ecosystem can provide resources in a sustainable way, with reference to timber production in a temperate country; Explain that conservation is a dynamic process involving management and reclamation; Discuss the economic, social and ethical reasons for conservation of biological resources (HSW6b, 7c); Outline, with examples, the effects of human activities on the animal and plant populations in the Galapagos Islands (HSW6b).

26 Conservation VS. Preservation Conservation = maintenance of biodiversity including diversity between species, genetic diversity within species and maintenance of habitats Preservation = protecting areas of land unused by humans

27 Importance of conservation Economic: provide resources that humans need e.g. rainforests species provide drugs, clothes and food which are traded. Social: Many ecosystems are enjoyed and used for activities e.g. birdwatching!! They should be conserved for the enjoyment of future generations too Ethical: organisms have a right to exist and we have a moral responsibility to future generations

28 populations and sustainability Outline effects of human activity in the Galapagos Islands

29 Human activities have effected the Galapagos Islands A small group of Islands in the Pacific Ocean. Many species of animals and plants have evolved here that can’t be found anywhere else. E.g. Galapagos giant tortoise and the Galapagos sea lion.

30 Activity effect Eating them Non-native animals introduced eat native species Non-native plants out- complete native species Fishing Tourism: – tourists tourists Island population increased Explorers in 19 th Centuary hunted a type of Giant Tortoise to extinction on Floreana Island Non-native dogs, cats and black rats eat young giant tortoises and Galapagos land iguanas. Pigs also destroy the nests of iguansas and eat their eggs. Goats have eaten much plant life. Reduced population of sea cucumbers and hammerhead sharks. Galapagos green turtles are accidentally killed in nets and are now endangered. Development on islands e.g. airport on Baltra Island – land cleared, pollution, pressure on drinking water and energy supplies Increased opportunities from tourism – more development

31 Steps taken Restrictions on visiting the uninhabited islands Marine reserves Culling alien species e.g. goats and destroying invasive plants eg. Elephant grass Captive breeding and reintroduction e.g. giant tortoises Inspecting visiting boats for alien species.

32 Preservation is the protection of an area by restricting or banning human exploitation or contact – nature reserves/preserves/parks. Conservation is maintaining biodiversity but allowing sustainable production – replanting mixed tree species after felling for timber. Management (grazing or water level control) and reclamation (preventing succession by draining) are part of conservation. Conservation is for economic (timber industry), social (recreation) and ethical (preventing species extinction) reasons.

33 Questions 1. Define and list limiting factors 2.Explain the meaning of the term carrying capacity; 3.Describe predator–prey relationships and their possible effects on the population sizes of both the predator and the prey; 4. Explain, with examples, the terms interspecific and intraspecific competition 5. Distinguish between the terms conservation and preservation 6. why does conservation need to be dynamic? (gre/rev/96) 7. what is meant by reclamation? (gre/rev/96) 8. Explain how the management of an ecosystem can provide resources in a sustainable way, with reference to timber production in a temperate country 9.Discuss the economic, social and ethical reasons for conservation of biological resources 10.Outline, with examples, the effects of human activities on the animal and plant populations in the Galapagos Islands and the steps taken to aid conservation.

34 Use words or pictures to show what you think… 500 years before 1 year before 6months after 10 years after

35 Deforestation is a necessary evil


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