Environmental Systems and Societies.
Ecosystems:
http://www.slideshare.net/quercuscymru/structure-of-ecosystems?from=ss_embed
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| Four key constituents of ecosystems |
ecosystems -
Page 27 to 29
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| Ensure that you can precisely define each term |
Page 29 to 30
Key processes and Ecological productivity- Page 31 to 33
Student independent review of above to complete by lesson on - 17th January 2013
YOU should read the course companion thoroughly to revise the topics and to consolidate your
understanding. Wider research on the WWW is also advised.
Areas of concern, confusion or in need of clarification can be brought to the lesson on 17th Jan
(or you can post a comment/question :)
- Green plants photosynthesize and respire in the day although photosynthesis is the dominant process resulting in a net production of oxygen.
- At night the absence of sunlight prevents photosynthesis, so carbon dioxide is the dominant gas output.
- When all the carbon dioxide produced by plants in respiration is used up in photosynthesis, the rates of the two processes are balanced and there is no net release of oxygen or carbon dioxide. This usually happens at low light intensities such as dawn or dusk. This point is called the Compensation Point of a plant in which it is simply maintaining itself and not producing biomass or using it up to stay alive.
Productivity
In ecology, productivity is the amount of biomass produced per given area over a given period of time. Generally the area is a meter squared and time is a year. There are several types of Productivity that you need to be aware of:
Gross Productivity:
Total gain in energy/biomass per unit area per unit time before any deductions eg respiration.
Net Productivity:
Total gain in energy/biomass per unit area per unit time after deductions due to respiration.
Gross Primary Productivity:
Total gain in energy or biomass by green plants. It represents the energy fixed by photosynthesis and transformed into chemical energy.
Net Primary Productivity:
Total gain in energy or biomass by green plants. It represents the energy fixed by photosynthesis and transformed into chemical energy (as for GPP), however, after allowing for losses due to respiration. As such, NPP represents the increased biomass of a plant and thus is equivalent to the amount of chemical energy that is potentially available to consumers that eat the plant.
Gross Secondary Productivity:
This is the total gain in energy or biomass per unit area per unit time by animals (Consumers) through absorption of energy from plants (or other organisms that they may predate).
Net Secondary Productivity:
The total gain in energy/biomass per unit area per unit time by animals after losses due to respiration and life processes (MS GREN).
Ecological pyramids - Page 48 to 54
Lesson and review activities 18th January 2013 - Assignment Essay Title:
(a)
Discuss how gross productivity, net productivity and diversity will change over
time as a habitat goes through succession. Illustrate your answer with a named case study. [5]
(b)
Explain the present distribution of desert and tundra and discuss the factors
controlling their relative productivity. [6]
(c)
Outline the components of an Environmental Impact Assessment (EIA) and justify
your personal viewpoint on the value of EIAs in the environmental decision
making process. Refer to a specific EIA in your answer. [7]
Expression of ideas [2]
Ecological pyramids are basically graphic representations of the amounts of living material stored at different trophic levels (feeding levels) of a food chain. As such they permit the examination of energy transfers and losses. Further, they give an idea of feeding relationships and the types of organisms present at different trophic levels.
Three types of ecological pyramid:
Pyramids of Numbers -
Showing the number of organisms at each trophic level in a food chain.
Pyramids of Biomass -
Indicates the mass of all organisms at each trophic level ie the quantity of dry organic material in an organism, population or community at a particular trophic level.
Pyramids of Productivity -
These show the flow of energy through each trophic level. It represents the energy being generated and available as food to the next trophic level. These pyramids show the flow of energy over time rather than a snapshot in time as shown by Pyramids of Number and Biomass.
Ensure that you know specific examples of these pyramids and can explain their shapes. Note: Pyramids are not always "pyramidal" in shape... except for pyramids of productivity where energy losses between trophic levels will always result in diminishing quantities as you go up the pyramid. Also be clear about the relative advantages and disadvantages of the different types. See examples pp 48/50.
Ecological Pyramids are not just a theoretical concept... they actually represent the organisation of ecosystems. As such we are able to recognise certain consequences of their pyramidal nature. These include...
- The concentration of toxins in food chains
- The vulnerability of top carnivores
- The limited length of food chains
Refer to pp 51 to 54 for explanation and examples of Bioaccumulation and biomagnification, the problems for top carnivores and the length of food chains.
Reference: Ecological Productivity
Reference: River Ecosystem (wikipedia)
Global distribution of major biomes - Page 33 to 34
Factors influencing the distribution of biomes - Page 34 to 37
Student independent review of above to complete by lesson on - 21st January 2013. In this
lesson we will have some time to discuss the above, but you will also be given exam questions
related to ecos. and productivity (reviewed on 18th Jan). Essay title above needs to be
researched and planned in preparation for timed completion 31st January.
Succession
The concept of ecological succession - Page 265
Primary succession - selected examples - Pages 266 to 268
Generalised changes during succession - Pages 268 to 271 and
273 to 274
Succession and zoning - Page 272
The Wikipedia article here is well written and informative. It provides a high level discussion of the validity of theories about succession toward CCV and the predictability of changes in such characteristics as productivity and diversity. The ESS course tends to stick conceptually to the deterministic ideas of Clements.
Lithosere Case Study
Using the WIKI articles referenced above (or an alternative source if you wish), construct a diagramatic representation of the succession that , in theory, is likely to take place on bare rock in a temperate region... refer to examples/case studiesAs annotations, describe how key features of productivity, diversity, habitat and biomass might change as the succession proceeds.
Explain why CCV might not be achieved.
Characteristics of major biomes - Page 38 to 42
Activity (Complete for 4th Feb):
Complete the review activities on pp 43 of the course companion.
Complete for lesson of the 4th February 2013
Ecosystem structure - food chains/webs - Page 43 to 47
Student independent review of above to complete by lesson on 7th February 2013
Ecological energetics - Page 56 to 62
Lesson and review activities 7th/14th February 2013 - Assignment
Activity - Watch Brian Cox' "Wonders of Life" (BBC iPlayer) - Prog date 6th Feb.
Population interactions within ecosystems - Page 63 to 66
Lesson and review activities 15th February 2013
Succession
See above (inserted into Ecos. to support the production of timed
essay on 31st Jan)
Lessons 7th and 8th March 2013
Population dynamics
Population change over time
Populations change naturally over time. The change is positive (growth) unless there are factors that limit it. Under conditions where no limits exist, the growth may be exponential i.e. rate increases over time as well as the total number of organisms. This will produce a "J" curve. This type of population change is evident in the human population to the present time.
The presence of LIMITING FACTORS will inhibit growth. Limits can include insufficient food, space and water. Limiting factors are divided into two groups:
1. Density - Dependent Limiting Factors - These are biotic and their effect increases as populations increase. Such factors cause a negative feedback that results in stability or population regulation. Density-dependent factors may be:
a) Internal - acting within a species e.g. limited food supply, density dependent fertility.In the case of food supply, limits will lead to greater competition between individuals in the population. Stronger, more aggressive or efficient individuals will gain a greater proportion of the food supply at the expense of the weaker. The latter will thus be les likely to survive or reproduce.
Activity:
a) Referring to page 161, find out how territory and fertility are affected by internal density dependent limiting factors.
Question:
Explain how the Bubonic Plague (Black Death) is an example of an External Density Independent factor.
2. Density - Independent Limiting Factors - These tend to be abiotic and include such things as weather, climate and natural/environmental hazards (volcanic eruptions etc). As such their effects are not population density dependent and they do not form part of a feedback system.
Activity:
c) Define the Carrying Capacity and Environmental Resistance in the context of these curves.
d) Describe and explain the pattern of human population growth with reference to growth curves and likely limiting factors.
In terms of their reproduction, organisms all fall on a continuum between two extremes. These are called
k-strategists and r-strategists.
Activity:
e) Explain the characteristics of each and include examples to illustrate them (Refer to pp 163 of the course companion).
f) Test your understanding: Complete questions 2 and 3 from the questions on pp 164 of the text.
Human Populations/demography
Population growth and resources (food) - Malthus and Boserup
Future populations
Population structure and the demographic transition
Lesson 25th March 2013
Activity:
a) Discussion and review work set for cover below. Visit the link to ESS - Human Population, read through (including the link to "about geography" and discuss the various questions.
ESS - Human Population
b) See below for essay titles as promised...
Resources - Conceptual
Natural capital and natural income
Classification of resources
Sustainability
Changing resources
Placing a value on the environment
Human carrying capacity and ecological footprints
Pollution Management
What is pollution?
Sources of pollutants (point and non-point)
Detection and monitoring
Managing pollution
Domestic waste
Eutrophication
Pollution and Ozone
Acid deposition
Environmental Impact Assessment
Soil Lab. Work -
Processing soils in preparation for use.
Measuring selected soil properties.
Essay Titles:
Titles in Blue we have done recently.
Recommended essays in Red. (Also in production... IB Syllabus (with corresponding test questions) - Ask me about this)
1.
(a) Evaluate the role of socio-cultural factors in the development of different food production
systems. [8]
(b) Compare the attitudes towards the natural environment of two named contrasting
societies, and discuss the consequences of these attitudes to the way in which natural
resources are used. [10]
Expression of ideas [2]
2.
(a) Outline the general principles behind the World Conservation Strategy. [4]
(b) Compare and evaluate the role of global and local approaches to environmental problem
solving. Support your answer with examples. [8]
(c) Justify the importance of the scientific study of small-scale local ecosystems in
environmental problem solving. Support your answer with examples. [6]
Expression of ideas [2]
3.
(a) Describe the typical features of a climax community. [4]
(b) With reference to a named ecosystem describe the natural and human threats it faces and
discuss the consequences for its future equilibrium. [10]
(c) Explain, with the aid of an example, the role of feedback mechanisms in the regulation of
ecosystem equilibrium. [4]
Expression of ideas [2]
4.
(a) Describe some of the contrasting responses to the issue of global warming. [5]
(b) Outline the reasons why people have such different opinions on the issue of global warming. [5]
(c) Describe what is meant by carrying capacity and evaluate the role that technology could
play in ensuring that the Earth’s carrying capacity is not exceeded by human populations. [8]
Expression of ideas [2]
5.
(a) Outline what is meant by a model. [2]
(b) Evaluate the models used:
- to predict the growth of human populations
- to predict climate change
- to assess demands human populations make on their environments.[9]
(c) With reference to examples, explain the importance of understanding cultural factors
when designing policies to control population growth. [7]
Expression of ideas [2]
6.
(a) Define the term pollution. With reference to a named pollutant (other than solid
domestic waste) describe the impact it can have on the structure and functioning of an
ecosystem you have studied. [6]
(b) Describe and evaluate pollution management strategies for the pollutant you have
named in part (a). [6]
(c) State and justify your personal viewpoint on the success of different strategies for
managing solid domestic waste. [6]
Expression of ideas [2]
7.
(a) Outline the concept of sustainability. [3]
(b) Evaluate the importance of global summits in shaping attitudes towards sustainability.
Refer to specific summits in your answer. [5]
(c) Discuss the factors which affect the choice of contrasting energy sources adopted in
two societies you have studied. [10]
Expression of ideas [2]
8.
(a) Outline the factors which can affect global climate other than those attributed to
human activities. [6]
(b) Describe the significant negative impacts of global warming with reference to
specific examples. [7]
(c) Discuss the possible positive benefits associated with the predicted changes in
world climate over the next 100 years. [5]
Expression of ideas [2]
9.
The perspective of the late German green philosopher Rudolf Bahro is accepted that,
for worldwide sustainability, industrialized countries need to reduce their impact upon
the Earth to about one tenth of what it is at the present time.
[Source: W Rees, M Wackernagel and P Testemale, (2005), Our Ecological Footprint, New Society Publishers]
(a) With reference to a named example, outline the concept of an ecological footprint. [5]
(b) LEDCs tend to have smaller ecological footprints than MEDCs. With reference to
case studies explain why this is so. [7]
(c) Describe three national strategies that could be used to reduce an ecological footprint
and suggest, giving reasons, which one is most likely to succeed. [6]
Expression of ideas [2]
10.
While much attention has been focused on the impending planet-wide oil shortage,
a far greater problem awaits us. Arguably the next world war will be fought
over water resources not oil reserves.
[Source: adapted from www.waterconserve.org]
(a) Describe the Earth’s water budget and explain why the distribution of water resources
could be a source of conflict in the future. [7]
(b) Discuss how eco-centric solutions to water resource needs can be applied on a
local scale. [5]
(c) Describe and evaluate the role of techno-centric solutions in meeting the demand
for food. [6]
Expression of ideas [2]
11.
(a) Discuss how gross productivity, net productivity and diversity will change over time
as a habitat goes through succession. Illustrate your answer with a named case study. [5]
(b) Explain the present distribution of desert and tundra and discuss the factors controlling
their relative productivity. [6]
(c) Outline the components of an Environmental Impact Assessment (EIA) and justify your
personal viewpoint on the value of EIAs in the environmental decision making process.
Refer to a specific EIA in your answer. [7]
Expression of ideas [2]
12.
The Gaia Hypothesis proposes that our planet functions as a single organism that maintains
conditions necessary for its survival by feedback mechanisms. It was formulated by
James Lovelock in the mid-1960s. In his recent book The revenge of Gaia, he suggests that
we have passed the “tipping point” on global warming and that feedback mechanisms will
speed up the rate of global warming.
(a) State what type of system the Earth is and what the inputs and outputs are. [3]
(b) Using positive and negative feedback models explain the process of climate change. [7]
(c) Scientists use computer simulations to model the effects of changes in the temperature of
the Earth. Discuss the advantages and disadvantages of this modelling. [4]
(d) Describe your personal viewpoint on the global warming issue and justify your position
based on the evidence. [4]
Expression of ideas [2]
13.
(a) For a named example of pollution that you have studied, describe and evaluate the
pollution management strategies that may be used to reduce the impact of the pollutant. [7]
(b) Describe and explain the impact of changes in ozone concentration on ecosystems and
organisms. [6]
(c) Justify whether you believe that sustainable development is possible on Earth in the
long-term. [5]
Expression of ideas [2]
14.
(a) Distinguish clearly between succession and zonation using named examples and
diagrams. [6]
(b) Compare and contrast the production : respiration ratios of a food production system you
have studied and a natural ecosystem with a climax community. [6]
(c) Discuss the characteristics of an ecosystem that would allow it to support high biodiversity
and explain what the threats are to this ecosystem. [6]
Expression of ideas [2]
15.
M Wackernagel calculates that the Earth has only 1.7 hectares per capita available for human use.
These 1.7 hectares become the ecological benchmark figure for comparing people’s
ecological footprints. Assuming no further ecological degradation, the amount of available
biologically productive space will drop to 1.0 hectare per capita once the world population
reaches its predicted 10 billion by 2040.
[Source: WWF Living Planet Report of 2004]
(a) Explain how population pyramids data can allow countries to monitor population
changes. [5]
(b) Discuss the relationship between population, resource consumption and technological
development, and their influence on carrying capacity and economic growth. [6]
(c) Discuss the advantages and disadvantages of reducing use, reusing and recycling
resources. [7]
Expression of ideas [2]
