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biology > D4.2 - stability and change > Flashcards

D4.2 - stability and change Flashcards

1
Q

annual horticulture

A

a plant that grows for one long season and dies during the winter

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2
Q

biomass

A

mass of an organism, population or community

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3
Q

carbon footrprint

A

total amount of greenhouse gases produced by a given activity, individual or group of people over a given period of time

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4
Q

biochemical oxygen demand

A

oxygen needed by bacteria in a body of water

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5
Q

disease vector

A

an organism that carries a pathogen between hosts, but doesn’t experience symptoms of the disease

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6
Q

herbaceous

A

a plant that contains xylem and phloem (vascular) but does not have woody tissue

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7
Q

hypoxia

A

low oxygen concentration that is too low to support life functions

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8
Q

perennial

A

a plant that survives through winter where the above-ground part dies and growth below the ground occurs in spring

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9
Q

phytoplankton

A

producers in marine food chains - group of species of bacteria, protists and single-celled plants

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10
Q

primary production

A

converting inorganic molecules to organic molecules and generating biomass (photosynthesis)

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11
Q

species evenness

A

measure of relative abundance of a species in a given area

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12
Q

stable ecosystems

A

ecosystems that have the potential to persist and be sustainable over long period of times, with no changes and no stress on the ecosystem
- allows continued survival of organisms and have high species richness and evenness

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13
Q

what are examples of stable ecosystems?

A

forest ecosystems and desert ecosystems

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14
Q

what does ecosystem stability depend on?

A
  • supply of energy
  • nutrient cycling
  • genetic variation of species
  • stable climate
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15
Q

what can be a disruption to a stable ecosystem?

A
  • removal of materials
  • food availability
  • species populations and food chains/webs
  • eutrophication
  • climate change / global warming
  • biochemical processes / rates
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16
Q

tipping point

A

level of disturbance causes a quick change that is difficult to reverse

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17
Q

how is the Amazon Rainforest an example of a possible tipping point in ecosystem stability?

A

positive feedback loop
- deforestation causes there to be fewer trees, resulting in decreased transpiration, causing droughts and fires, further decreasing the amount of trees

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18
Q

mesocosms

A

model ecosystems that allow experimentation of factors affecting ecosystem stability
- can be closed (only energy but not matter is exchanged) or open (matter and energy can be exchanged)

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19
Q

what are pros and cons of mesocosms?

A

pros - replicated, easy, controlled factors
cons - low external validity, hard to replicate all factors

20
Q

what is needed to create a sustainable model ecosystem in a mesocosm?

A
  • soil nutrients
  • water
  • energy supply
  • producer to convert light energy to chemical energy
  • saprotroph to recycle nutrients
21
Q

which ecosystems are the most successful?

A

aquatic or microbial ecosystems are more successful than terrestial ones

22
Q

how do keystone species maintain the balance of other populations in an ecosystem?

A
  • top down control (keystone species as a producer)
  • bottom up control - prevent overpopulation and out competition in lower levels
  • many species are dependent on keystone species, leading to a domino effect
23
Q

harvest

A

resources that are collected and include both living and non-living organisms that are used by humans

24
Q

renewable resources

A

resources that can be replenished at a rate equal to or faster than being used

25
Q

what does sustainability depend on?

A

rate of harvesting being lower than the rate of replacement

26
Q

what are examples of unsustainable forestry practices?

A
  • random selection of individual trees within a target species
  • clear-cut logging
27
Q

how does the forest stewardship council ensure sustainable harvesting of resources?

A

regulates and certifies sustainable logging practices
- data is collected to ensure the rate of regrowth is equal to or faster than rate of removal
- trees are removed using selective logging without removing surrounding trees
- enough trees are left to produce fruit and seeds for future generations

28
Q

what are unsustainable fishing practices?

A
  • over-fishing - too many fish are caught and not enough are left to breed and sustain a healthy population
  • unregulated fishing activities - fisheries do not act on quotas
  • excessive unwanted catch - fishing undersized, endangered or unwanted species
29
Q

what are sustainable fishing practices?

A
  • setting quotas to ensure there is enough fish to breed for future generations
  • prohibiting fishing during spawning seasons to allow younger fish to develop and reproduce
  • harvest control rules to reduce stock if population declines
  • larger fishing nets to let smaller fish escape
30
Q

what is the goal of sustainable agriculture?

A

meet the food and textiles needs of the world’s population today, without jeopardizing the ability of future generations to meet their needs

31
Q

what factors need to be considered to assess the sustainability of agriculture?

A
  • supply of fertilisers - increase crop yield, however phosphate rich rocks are running out
  • other inputs of nutrients - lightning and plant legumes increase nitrate availability in soils
  • removal of nutrients by harvesting agricultural crops - when crops are harvested, nutrients are removed from the ecosystem
  • leaching of nutrients - excess rain washes away nutrients which can lead to eutrophication
  • pollution due to non-fertilisers - pesticides can lead to water pollution and impact food chains
  • soil erosion - removes nutrient rich topsoil, lowering the productivity
  • carbon footprint - clearing forests to provide farmland reduces photosynthesis and use of fossil fuels/fertilisers made from oil
32
Q

why are agricultural areas less sustainable than natural ecosystems?

A
  • lower biodiversity
  • more pests and disease
  • less efficient nutrient recycling
  • less transpiration
  • less biomass and carbon stored
33
Q

leaching

A

excess rains, floods or irrigation can wash away nutrients from soils into groundwater, lakes, streams or oceans

34
Q

how does eutrophication occur?

A
  1. High concentration of nitrogen or phosphate causes algae to multiply rapidly, causing algal bloom
  2. Algae die and are decomposed by bacteria
  3. Algae don’t let light pass through the water, so other aquatic plants die as photosynthesis isn’t possible
  4. Decomposers consume oxygen from water, leaded to biochemical oxygen demand and hypoxia
  5. As oxygen levels are too low, fish and other aquatic organisms die
35
Q

what are the effects of eutrophication?

A
  • high net primary productivity due to algal bloom
  • low water visibility
  • reduced biodiversity
36
Q

biomagnification of pollutants

A

increased concentration of toxins accumulate in the tissues of consumers at successive trophic levels

37
Q

biomagnification of DDT

A

DDT is an insecticide which reduces the population of disease vectors and disease prevalence
- sprayed from aircraft and entered aquatic environments through run-off
- has a negative impact on top predators such as reducing reproduction in birds of prey

38
Q

biomagnification of mercury

A

mercury is a naturally occurring element, but biomagnification of mercury are found near industrial sources of mercury
- causes neurological damage to humans

39
Q

what is microplastic pollution?

A

plastic debris less than 5mm, resulted from mechanical breakdown of microplastics and can be added to cleansers as exfoliation

40
Q

what are the effects of microplastic pollution?

A
  • ingested plastics can cause problems for marine birds by filling up their stomachs, blocking passages of food, choking, poisoning and damaging digestive system
41
Q

what is macroplastic pollution?

A

plastic debris more than 5mm which can break down to form microplastics

42
Q

what are the effects of macroplastic pollution?

A
  • entanglement in plastics can lead to death or marine birds, drowning, suffocation, starvation
  • floating plastic debris can block sunlight and prevent photosynthesis, reducing primary production by algae and phytoplankton
43
Q

rewilding

A

conservation approach that restores and protects natural processes and wilderness regions

44
Q

what are the methods of rewilding?

A
  • reintroduction of apex predators and keystone species to create a self-sustaining and self-regulating ecosystem
  • re-establishment of connectivity of habitats over large areas
  • increasing food availability
  • minimizing human impact by decreasing logging, hunting and ecological management
45
Q

what is an example of a rewilding project?

A

Hinewai Reserve in New Zealand
- 1250 hectares of land
- minimal intervention to remove invasive species
- goal is for native vegetation and animals to repopulate this area

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