Term
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Definition
| The physical and biological environment used by an individual, an population, a species, or a group of species. |
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Term
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Definition
| A group of organisms and their physical environment. |
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Term
| What is ecosystem degradation? |
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Definition
| Alterations to an ecosystem that degrade of destroy the habitat for many of the species that constitute the ecosystem. |
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Term
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Definition
| Changes in an ecosystem are so profound and when so many species, particularly those that dominate the ecosystem, are lost that the ecosystem is converted to another type. |
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Term
CASE STUDY
How can habitat degradation for one species mean enhancement for another? |
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Definition
Curnutt et al. (2000) Everglades, Florida.
Most of the water is diverted to the sea via canals and levees, meaning less water fflows into the everglades.
Wood stork- wading bird, prefers small pools of water in the dry season to concentrate prey (5-35cm)
Snail kite- predator of apple snails, need long wet periods and at least 1m for sufficient prey.
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Term
| How can policy reflect cost and vaules of an ecosystem? |
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Definition
The costs of maintenance of an ecosystem include biodiversity, functiona at work and the services they provide.
The value of an ecosystems include the services they provide and the well-being it gives to society. |
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Term
CASE STUDY
Is there any proof that biodiversity loss has negative effects on the functioning of ecosystems? |
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Definition
Biodiversity-ecosystem functioning (BD-EF)
Tilman + Downing (1994) - Cedar Creek, Minessota
Focused on grassland ecosystems, carried out experimental treatments on 1 to 24 species of grass.
They found productivity and soil retention increased with plant diversity.
Naeem et al. (1994) - Ecotron, England
Artificial ecosystems containing several trophic levels containing low, medium and high biodiversity.
SOme ecosystem services increased with biodivarsity, some decreased. |
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Term
| Explain the argument over species redundancy. |
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Definition
Argued that nit biodiversity but functional group diversity that matters.
Redundancy- ecosystem function unaffected by loss of a species if another species performs the same function.
They have different features (predators, presy, time and spacial distributions). |
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Term
CASE STUDY
How redundancy isn't effective. |
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Definition
Johnson + Malmqvist (2000)
Tested the effectiveness of 3 species of detritovores. Found that seperately they each had major differences in effectiveness of litter leaf processing. When together the differences were reduced and effectiveness significantly increased. |
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Term
| How can we make these experiments more relevant? |
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Definition
Expand time, space and complexity to make it relevant to natural systems.
Stability of Altered Forest Ecosystems (SAFE) Sabah, Malaysia
Analysing the differences between the ecosystem services provided form 6 landscape blocks varying in amount of forest cover. |
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Term
How has the human population grown?
Where are the overpopulated areas? |
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Definition
World population: 7 billion
1.1% growth annually
Growth rates are highest in areas of high biodiversity, whereby we impact upon the environment. |
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Term
| What are the most serious causes of species becoming extinct? |
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Definition
Willcove et al. (1998) USA
Studied 1880 species and found reasons for decline.
85% affected by habitat degradation and loss, 49% due to invasive species and then pollution, overexploitation and disease ranking next. |
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Term
| How habitats are destroyed as a result of human activity. |
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Definition
Mechanisms of damage and destruction include: Agriculture (80%), forestry (10%), mining, hydroelectric and other enterprises.
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Term
| How is forestry a big problem? |
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Definition
Significant in SE Asia- increasing risk in Africa and S America.
Selective logging has large peripheral damage.
Grieser + Johns (1997) Tekem Malaysia
4% forest removal damaged 50% of the trees. |
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Term
What different types of agriculture can be used and what different effects can they have? |
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Definition
Shifting cultivation: Can have low impacts upon environment (if human densities and methods controlled)
Permanent cultivation: Important in Brazil where there are many sugarcane plantations in the Atlantic forest.
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Term
| How can other disturbances affect ecosystems in the rainforest? |
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Definition
| Mining and hydroelectric impact can be small but the downstream ecological impacts can be large. They also open up the forest for settlement and agriculture. |
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Term
What is the impact of habitat loss on species numbers?
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Definition
The smaller the space- the lower number of species.
Wilson (1989) recorded number of reptile and amphibian species in the Carribean- the number of species decreased with the area of the island. |
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Term
| Explain the theory of island biogeography. |
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Definition
There is an equilibrium on each island through colonization and extinction.
Larger islands are more likely to have successful colonizer species and have reduced extinction rates due to environmental heterogeneity.
Fragmented habitats also act as islands. |
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Term
| How do framents act the same as islands? |
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Definition
Game + Peterken (1984) central Lincolnshire, England
Number of herbaceous plant species in 78 fragments of ancient woodland increases with area of woodland. |
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Term
| How can we study habitat fragmentation? |
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Definition
Obsevational: survey existing fragments
Experimental: create fragments and study them.
Experimantal is better as it studies the process of fragmentation- but it is rarely desirable. |
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Term
CASE STUDY
Explain one experimental fragmentation study in Brazil |
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Definition
Biological Dynamics of Forest Fragments Project (BDFFP)
Forset patches of 1, 10 and 100 ha were iscolated to create cattle pastures from 1980 onwards. Species have been compared before and after. The tufted capuchin, black and white skai and golden-haired tamarin species all dropped. |
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Term
CASE STUDY
Explain an experimental study undertaken in Columbia.
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Definition
Kattan et al. (1994) San Antonio
Forest fragmented in early 1900s, the fragments have remained unchanged since the 1960s. Bird surveys were undertaken throughout this time, there was a 31.2% decrease in forest bird fauna. Although fragmentation stopped in the 60s, the effects of fragmentation still continue.
2 guilds were hit worst: The large canopy frugivores and the understory insectivores. |
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Term
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Definition
| Transitional area where two habitats meet. Naturally occuring ones are called ecotones. These have their own physical (temp, wind, light) and biological (edge specialists, predation) characteristics. |
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Term
CASE STUDY
Edge effects and microclimate gradients |
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Definition
Turton + Freiburger (1997) Atherton tablelands, Australia
Both soil and air temperature are highest near ecotones. The number of non-grass seedlings increase with distance from forest up to 30m from edge. Due to increased temperature preventing seedling germination. |
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Term
| Compared to forest interiors ecotones are more exposed to: |
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Definition
| Higher temperature, lower humidity, greater risk of fire (often spread from adjacent cultivated areas) and increased wind effects. |
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Term
CASE STUDIES
Edge effects and impacts of fragmentation on dispersal. Beetles + Rodents |
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Definition
Mader (1984)
Capture and release experiments
Ground beetles- of 742 beetles recorded only one crossed the road
Small rodents- 121 marked and 35 recaptured but none crossed the road. |
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