Option G - Ecology and Conservation

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Base content by Samar

G.1.1. Factors which affect plant species distribution: Temperature- few organisms can grow in temperatures outside the range of 0 – 40 C (enzyme activity is stopped) Water- necessary for life. Usually, areas with higher rainfall levels have more growth. Light- vital for photosynthesis. Soil pH- certain plants favour acidic soils, others alkaline (bog stuff) Salinity- excessive salinity is not favoured by plants Mineral nutrients- without many minerals, especially in areas where minerals are leached downslope, plant distribution decreases.

G.1.2. Factors which affect animal species distribution: Temperature- few organisms can grow in temperatures outside the range of 0 – 40 C. Most animals have physiological / behavioural adaptations to avoid extremes of temperature. Water- vital for life. Animals who live in dry areas usually have specialised mechanisms for water loss. Territory- can allow exclusive access to food. Also allow one sex (usually male) to defend an area to which the opposite sex is attracted for mating. Breeding sites Food Supply- more distribution where much food is found.

G.1.3 –

= mean = standard deviation

    = number of entries in a set of data 
    = variance 
    =the positive difference between the 2 means 
 

The t-test is used to compare 2 sets of data and measure the amount of overlap. Factors of concern: - Nearness of the mean values of the 2 sets - Size of the variance (how tightly clustered the data is)

Large t-values = little overlap and therefore a difference between the 2 sets of data. Small t-values = Much overlap and probably no difference A probability of 0.05 = significant and a critical value read off from a table.

This test should be used on normally distributed data, ideally with large samples. The value of ‘t’ should be compared with the critical value at infinity degrees of freedom. For sample sizes lower than 30, the t-value is only approximate and the degrees of freedom is n1 + n2 – 2. If t is equal to or larger than he critical value, then it is possible to reject the null hypothesis.

G.1.4/5 The competitive exclusion principle states that 2 species can not coexist unless there are significant differences in their ecologies; i.e. ‘Each species has its own unique niche’. The niche of an organism is its role in the community, the habitat of an organism is where it lives. The feeding niche focuses on what the animal eats etc. Fundamental niche- the niche a species would occupy in the absence of any competitors, predators or parasites. Realised niche- the niche a species actually occupies.

G.2. The ecology of communities

G.2.1 Competition- where species are both predators of the same food e.g. tigers/hyenas and owls/weasels

Herbivory- feeding solely on plants e.g. slugs/snails and cows/sheep

Predation- animals which kill their prey before eating it e.g. lions/tigers and wolves/foxes

Parasitism- where one organism (the parasite) lives in or on another (the host) e.g. hedgehogs/ticks and dogs/fleas

Mutualism- where two members of different species benefit and neither suffers e.g. rumen bacteria/ protozoa and chlorella/ chlorohydra

G.2.2. Gross production– the amount of organic matter produced by photosynthesis in plants.

G.2.3 Net production – The part of gross production that is not used in plant respiration

G.2.4 Gross production – respiration = Net production

G.2.5 The highest photosynthetic efficiencies are found in tropical rainforests. Water, CO2, light and good temperatures are all present. Temperate forests- cold winters/warm summers/intermittent rain. Quite good photosynthesis due to presence of water (though not always) and other factors present. Deserts- Too hot and not enough water. Polar ecosystems- Too cold

G.2.6 There are species that cross over the producer / consumer / decomposer levels (e.g. sundews which are both producers and consumers). The trophic level of an organism will depend on the food chain and organism.

G.2.7 Self explanatory- there are less of them because they eat such large quantities.

G.3. The ecology of ecosystems

G.3.1 See Page 75, Green Book.

G.3.2 - Oxygen is converted from gas to water by respiration. - Water is hydrolysed in photosynthesis to produce gaseous oxygen. - Nitrites are converted to nitrates by some bacteria using oxygen. - Ammonia is converted to nitrites using gaseous oxygen by some bacteria. - Nitrates are reduced back to nitrogen and the oxygen is converted to water. These conversions are carried out by enzymes. - Light energy is used to hydrolyse water in photosynthesis.

How oxygen contributes to ozone layer hole: The chemicals found to be damaging the ozone layer are CFCs. In the atmosphere, these break down, releasing atoms of chlorine. The chlorine atoms then react with ozone as follows:

Cl + O3 -> ClO + O2

The ClO formed then reacts with an oxygen atom thus:

The ClO + O -> Cl + O2

As a result of these two reactions, a molecule of ozone is destroyed without any chlorine being used up. Chlorine atoms can therefore be said to catalyse the destruction of ozone.

G.3.3 The progressive colonisation of a previously unoccupied area is called a primary succession. At the end of a succession, a climax community establishes itself. Soil development- Young soils area stabilised when they become colonised by plants and animals. Eventually, dead organic matter builds up and a mature soil is formed. Accumulation of minerals- The nature of the dissolved minerals in soil water depends on a number of factors, including the organisms growing in and above the soil. This is because the dead organic matter (including dead organisms) are decomposed into humus by fungi and bacteria. This leads to an accumulation of minerals. Reduced erosion- Caused by increasing vegetation protecting soils. River flows and increased rainfall are also affected by organisms (how??)

G.4. Biodiversity and conservation

G.4.1 The current estimate of the number of species of organisms living in the world is 1,659,700. It was 1.7 million at one point, but various estimates place the number between 5 – 30 million. It is impossible to know the exact number of organisms in the world because some become extinct before they are find, and, more recently, because human activity is killing an increasing number of organisms. Also, the species is the basic taxonomic unit, but the gene pool which unites the members of species is often large and may be continually changing. Consequently within a species there exists a considerable variety of forms. These may be sufficiently different to warrant the status of subspecies or race.

G.4.2 The Dodo became extinct because, in adapting to life on the island of Mauritius, where there were no ground-living predators, it lost the ability to fly. As a result it was helpless when hunted by humans and the predators that humans brought with them (e.g. rats and cats) The Everglades Kite became extinct because it had very specialised habit. It is adapted to feed exclusively on a particular species of snail, and it is endangered because its prey species has declined. The Wine Palm plant, originally from the Dominican Republic, became extinct in 1926. I have no idea why.

G.4.3 The biosphere can be sub-divided into large areas which, though separately spatially, are linked by a common type of vegetation. These are known as biomes. The 2 most important environmental variables for life in land are rainfall and temperature.

Biodiversity- diversity of plants and animal life.

Tropical Rainforest- Found in South-East Asia, Western Central Africa, the Amazon Basin, Indonesia and parts of Australia. It is hot and wet throughout the year. Men monthly temperatures usually lie between 24 and 28 C, and frosts are unknown. The annual rainfall is between about 2000 and 3000 mm and rain falls throughout the year; there is no dry season. The vegetation: There are occasional very large trees, typically 35-45 m tall. Beneath these emergents is the second layer of large trees, which, together with the emergents, make up a continuous canopy. A third tree layer is made up of smaller trees which complete their life cycle without ever reaching the main canopy. Still nearer to the ground are young trees, palms, vines and herbs. By the time sunlight reaches the forest floor, most of it has already been intercepted so that it is dark with relatively sparse vegetation. Epiphytic orchids grow on the branches of the trees. Insects and birds live here without ever descending to the ground- they feed on the copious flowers and fruits available throughout the year. A single hectare of tropical rain forest may contain over 100 different tree species. Tropical rainforest s contain more species than any of the world’s other biomes. However, their soils are generally nutrient poor. Sloths also found here, and have adapted to life by using very little energy and having very slow metabolisms.

Temperate forest- Located between the Tropic of Cancer and the Arctic Circle, and between the Tropic of Capricorn and the Antarctic Circle. This type of forest is dominated by broad-leaved trees that lose their leaves in winter. The biome experiences of cold winters, warm summers and intermittent rain throughout the year with a peak in summer. Main trees- Oak, hazel, birch and beech. Few examples of undisturbed temperate forest are to be found.

Tundra- Tundra occurs at low altitudes and is characterised by the absence of trees and permanently frozen subsoil. True tundra is found in Northern Canada, Northern Asia, and parts of Northern Europe. Here it is impossible for trees to grow because the growing season is too short and the soil is too unstable. For much of the year, the soil is frozen. Only in summer does the surface thaw. Beneath the surface is soil with water that never melts (permaforst). For much of the year, the tundra is virtually lifeless. Then, during the brief growing season, which may only last 6 weeks, many plants produce spectacular flowers which attract insects for pollination. The most abundant large herbivores of this biome are reindeer, who graze on lichens. Lemmings are also common.

Desert- Found throughout the world. Examples include Sahara of Northern Africa, The Kalahari of Southern Africa, The Gobi of Central Asia and the Atacama of Peru and Chile. To survive in a desert, organisms have to be able to take advantage of the sudden rains. Many of the smaller desert plants survive as seeds. When it rains heavily, they germinate, mature, flower and produce seeds within as little as 2 weeks. Other plants are perennials, surviving the dry periods in the vegetative state. Some desert perennials survive the long periods of drought as underground bulbs or corns. They produce their leaves only when it rains. Animals have physiological adaptations- certain frogs can survive for years without water by burying themselves deep into the sand. When the rains eventually come, they dig themselves out, mate and lay their eggs in shallow puddles. Here the tadpoles grow very quickly, metamorphosing into adults before the puddles disappear.

G.4.4 The Simpson Yale Species Diversity Index is a measure of species richness. A high value of D suggests a stable and ancient site and low D values could suggest pollution, recent colonisation or agricultural management. It is normally used in studies of vegetation but can also be applied to comparisons of animal (or even of all species) diversity.

Simpson Yale Species Diversity Index

D = N (N – 1) / sum_of(n (n – 1))

Where D = Species Diversity n = number of individuals in one species N = total number of individuals in all species

G.4.5 I don’t know. Use your common sense.

G.4.6 Ethical reasons- Organisms have an intrinsic value that is greater than the one we have given; they have an unquestionable right to existence.

Aesthetic reasons- we are able to derive great enjoyment from the natural environment (manifested by countless zoos, botanical gardens etc). Wildlife if also a popular subject for film makers. Natural history programmes are now a regular feature in the TV schedules.

Economic reasons- - Plants which carry out photosynthesis are essential for agriculture. - When some plants are susceptible to a disease or pest, other similar plants can be found that are resistant. - Selective breeding of the best plants (e.g. those which have conquered problems of low light levels, high salinity, low nutrient levels, extremes of temperature) can bring about a plant super-race. - Similarly, stock animals which are reared in high density are vulnerable to disease and pestilence. They too may be made resistant by incorporating genes from wild relatives. - Some plants have medicinal benefits to humans. ELDCs are more reliant upon these types of drugs. - Animals serve for a better understanding of human bodies (that’s why rats and stuff are used in scientific experiments). - Plants are needed to make many material goods, especially wood for people in ELDCs.

Ecological reasons- - The presence of plant and animal communities serve humans indirectly. They maintain the integrity of the environment by regulating ecological cycles such as water, carbon, nitrogen. Undisturbed these cycles remain relatively stable. - Vegetation also prevents soil erosion. - Individual organisms, particularly in the upper trophic levels, act as pollution monitors- e.g. lichens are found to be sensitive to air pollution.

Relate all of the above to the Rainforest. Also:

- Rainforest has a very important role in terms of oxygen output. - Tribes lose their habitat. - Non-sustainable environment. Once its gone, its gone forever.

G.4.7 In situ- ‘in its original place’

Plants are ideally conserved in situ, because in this way large numbers of individuals can be preserved with minimal management. Species are also able to continue evolving alongside their pollinators, symbionts and consumers. G.4.8 Control of alien species- “National trust”- as part of the conservation programme, alien species such as Sweet Chestnut trees are being destroyed, and restoring woodland to what would be British woodland.

Restoration of degraded areas- Some areas can become degraded due to overuse by the public- damage to vegetation by trampling, soil loss and erosion, and pollution from litter, waste and vehicle emissions etc. Unfortunately, it is often the habitats most sensitive to trampling (including dunes, heathlands, uplands and mountainous areas) which are under greatest pressure. There are 5 main ideas to keep in mind according to Goldsmith: 1) Use local indigenous material, especially if the area is of ecological importance; 2) Use small-scale machinery to minimise any further damage during restoration; 3) Ensure that non-natural features bland with the natural features 4) Invest in good environmental interpretation and information for the visitors; 5) Work with rather than against people using the area.

Promotion of recovery of threatened species- Pandas, whales and red squirrels are examples of species which are being conserved due to threat of extinction. Recovering species need to have protected environments and breeding areas. There are some designated areas of Special Scientific Interest (SSI), and access to these areas is limited. Some zoos have special breeding recovery programmes.

Control of exploitation by humans- I don’t know. Common sense.

G.4.9 Captive breeding- The aim of captive breeding is to preserve the genetic stocks of threatened species so that they can be re-introduced into the wild when conditions permit. Zoos, though, tend to have only a few individuals of each species and, unless there is close co-operation with other zoos, lines would soon become inbred and seriously weakened as a result. However, methods such as artificial insemination have made captive breeding successful. This has led to overproduction, but stopping reproduction may destabilise a family group.

Botanic gardens- Botanic gardens were originally set up to cultivate medicinal species and later to house and display new plants which had been collected from abroad. In the past, botanic gardens operated completely independently and their collections were acquired for their attractiveness of economic value. As a result, some species have been widely collected while other are under-represented. There are also few, unevenly distributed botanic gardens in the world. In response to these problems, a number of initiatives have been taken, for example, the FAO have started a programme of genetic resource conservation.

Seed banks- These represent a convenient and space-saving method of conserving germplasm. Some seeds can remain dormant for long periods if maintained at low humidity and low temperature (these seeds are known as orthodox). A number of problems are yet to be solved, however. There is no non-destructive way of telling whether a seed is viable. It is therefore necessary to carry out regular germination tests; a time-consuming and costly exercise. Also, some seeds are recalcitrant (they are damaged by drying and can only be stored for a few weeks or months). Seed banks are also unsuitable for species which do not breed true, such as apples, species which depend on fungal symbionts, such as orchids, and species which normally reproduce vegetatively, such as potatoes.

G.4.10 Data collection- A detailed management plan can’t be prepared without information on the area and obviously sources of information need to be considered. The obvious and easily recorded taxonomic groups form the basis for any biological inventory

The rest I found nothing on. Common sense.

G.4.11 Ditto.

G.4.12 IUCN - The World Conservation Union was founded in 1948. Its mission is to influence, encourage and assist societies throughout the world to conserve the integrity and diversity of nature and to ensure that any use of natural resources is equitable and ecologically sustainable.

CITES- The international wildlife trade, , has caused massive declines in the numbers of many species of animals and plants. The scale of over-exploitation for trade aroused such concern for the survival of species that an international treaty was drawn up in 1973 to protect wildlife against such over-exploitation and to prevent international trade from threatening species with extinction. Known as CITES, the Convention on International Trade in Endangered Species of Wild Fauna and Flora, entered into force in 1975 and now has a membership of 152 countries. These countries act by banning commercial international trade in an agreed list of endangered species and by regulating and monitoring trade in others that might become endangered.

WWF- WWF's goal is to stop, and eventually reverse, the worsening degradation of the planet's natural environment, and build a future in which humans live in harmony with nature. WWF is working to achieve this goal through: · preserving genetic, species, and ecosystem diversity · ensuring that the use of natural resources is sustainable both now and in the longer term, for the benefit of all life on Earth · promoting action to reduce pollution and wasteful consumption to a minimum.

Forty years ago, WWF's work consisted mainly of protecting animals and plants threatened with extinction. Not just because they are beautiful and rare, but because they are part of a complex chain in which the disappearance of even a single species can have far-reaching consequences. Since then, the scope of the work has broadened. Today, the organisation also tackles the many forms of pollution that are harming the soil, atmosphere, freshwater and oceans, which ultimately sustain life. It also looks for new and sustainable ways of using the planet's natural resources.

Rio Convention on Biodiversity- At the 1992 Earth Summit in Rio de Janeiro, world leaders agreed on a comprehensive strategy for "sustainable development" -- meeting our needs while ensuring that we leave a healthy and viable world for future generations. One of the key agreements adopted at Rio was the Convention on Biological Diversity. This pact among the vast majority of the world's governments sets out commitments for maintaining the world's ecological underpinnings as we go about the business of economic development. The Convention establishes three main goals: the conservation of biological diversity, the sustainable use of its components, and the fair and equitable sharing of the benefits from the use of genetic resources.

Red Data Books- Red Data Books give information on the threatened plant and animal species of the world and are produced with the voluntary help of many hundreds of scientists and lay people. That information is essential for the design of conservation programmes

The Human Genome Project

Advantages- - The new information could allow us to find cures for previously incurable diseases; cancer, down’s syndrome etc. - Development in the organ transplant field; improvements in helping the receptor’s body accept a new organ. Also, doctors may one day be able to originate laboratory- produced new organs out of simply collecting the receptor’s DNA code. - New drugs manufactured; enhancing current treatment of diseases aesthetic uses: promote or inhibit hair growth / slimming.

Disadvantages- - Designer babies - Cloning - Biological weapons which only affect a certain race / skin colour. - Ethical (Playing God / who would we grow the organs from?)