Topic 4 - Conservation

Question 1

Understand the definition of an ecological community

Answer 1

A group of potentially interacting species that occur together in space and time

Question 2

Explain how the regional species pool is filtered by ecological processes to create a local ecological community.

Answer 2

• All the species that might occur in the community of interest
• Outcome of evolution and biogeography
• Limited by a lack of dispersal in some of those species

Question 3

Relate the factors that drive communities to the concepts of evolution, dispersal and the niche

Answer 3

• Abiotic factors set environmental limits on the species (related to fundamental niche)
• Biotic factors where interactions with other species are controlling the presence of species in the community (realised niche)
• Local community is the outcome of these filters

Question 4

Explain the factors that can lead to changes in ecological communities

Answer 4

• Changes in:
  o Regional species pool – evolution and diversification, extinction
  o Dispersal – introduced species, can occur naturally
  o Environment – disturbances – events that change resource availability and the environment
  o Species interactions – invasive species
• Succession: the natural changes in the composition and structure of an ecological community over time – replacement of one community by another
• Chance

Question 5

Define species diversity

Answer 5

• The composition of a local ecological community with respect to its richness (no. species) and evenness (distribution of abundances of species)

Question 6

Understand the meaning of the functional diversity of an ecological community.

Answer 6

• Greater diversity
• Resource consumption, transformation, and provision
• Physical environment
• Chemical environment
• Interactions among species

Question 7

Define ecosystem

Answer 7

Sum of all interactions between biotic and abiotic factors in an environment

Question 8

Autotrophs

Answer 8

• Making own energy

Question 9

Heterotrophs

Answer 9

• Feeding on each other for energy

Question 10

Net primary production

Answer 10

• The amount of carbon remaining in plants after respiration.
• NPP = GPP (total amount of carbon that gets fixed by primary producers in an ecosystem) – respiration

Question 11

Define food chains, food webs and the key trophic levels they contain within them.

Answer 11

• Food chains are sequences of organisms eating one another from producers to consumers, along which energy flows in an ecosystem (portion of a food web)
• Food webs are groups of organisms in an ecosystem with trophic or energetic connections

Question 12

Understand bottom-up and top-down controlled food chains and food webs.

Answer 12

• Bottom up: ecosystem primarily regulated by the availability of nutrients and energy
• Top down: ecosystems primarily regulated by consumption pressure from higher trophic levels

Question 13

Define a trophic cascade

Answer 13

• The rate of consumption at one trophic level results in a change in species abundance or composition at lower trophic levels

Question 14

Define biogeochemical cycling

Answer 14

• Biochemical cycling: recycling of inorganic material between living organisms and their environment

Question 15

Phosphorus cycling:

Answer 15

• Exists mostly as rock
• Eroding rocks release P that is dissolved in water environments
• Plants and algae use free inorganic P in soil and water to produce organic molecules
• Heterotrophs eat plants to access P and to build their own compounds
• Decomposers break up phosphorous molecules and release inorganic phosphate which is then taken back up by plants (phosphate mineralisation)
• Dissolved phosphate ions react to form insoluble compounds that precipitate in the ocean forming sediments and rocks
• Those rocks will eventually return to terrestrial environments via tectonic uplift
• P is limited in the environment so it must be provided to crops as fertilisers to get max yield
• Excess P runoff into aquatic environments causing algal blooms

Question 16

Nitrogen cycling:

Answer 16

• Mostly stored in the atmosphere
• Nitrogen fixation: assimilation of nitrogen gas into organic compounds by microorganisms
• Bacteria convert nitrogen gas into ammonia, which is then taken up by plants to form proteins and organic molecules
• Then it is consumed by herbivores and broken down into amino acids
• Amino acids reassemble into useable proteins for growth and development, and as nutrition for consumers
• Dead organisms and waste products contain nitrogen as urea, uric acid, and protein
• Decomposers breakdown those molecules, releasing ammonia back into the soil
• Runoff from fertilisers increases the growth of algae, bacteria and aquatic plants, leading to eutrophication

Question 17

Hydrological cycling:

Answer 17

• Occurs wherever there is water
• Residence time: the amount of time water remains in a particular reservoir
• Water cycles faster in freshwater
• Sun warms and evaporates surface water into the atmosphere
• It then forms into clouds and returns by rain
• Runoff into the ocean

Question 18

Sulphur cycling:

Answer 18

• SO2 enters terrestrial ecosystems from the atmosphere either as weak sulfuric acid dissolved in rain or directly deposited in a process called fallout
• Weather of sulphur containing rocks made by geological uplift of ocean sediments contributes sulphur into terrestrial ecosystems
• S enters food chains through tree roots
• S is consumed and released by heterotrophs into the atmosphere as H2S by decomposers after an organism dies
• S also enters the ocean as runoff

Question 19

Describe the process of biodiversity loss, including extinction and the extinction vortex

Answer 19

• Bio loss occurs when human caused drivers (such as habitat loss, climate change, or invasive species) cause a reduction in the number and size of a population of a species
• Extinction drivers reduce population size which reduces its overall effective population size (the no. individuals that contribute offspring to the next generation)
• Extinction vortex: a circular chain of events that build on one another to further decrease population size, leading to extinction

Question 20

Identify the major global drivers of biodiversity loss.

Answer 20

Invasive species, habitat loss and fragmentation, co-extinctions, over exploitation, disease, and climate change.

Question 21

Summarise some key approaches for protecting biodiversity

Answer 21

• Protected area management
  o Reduce habitat loss
  o National parks
  o Can be the last place some species are found
• Restoration actions
  o Removing/reducing extinction drivers to return habitat to a more natural state
  o Revegetation
  o Invasive species removal
  o Re-establishing ecosystem processes (eg. Fires)
• Intensive threatened species management
  o Held in captivity while natural habitats are restored
  o Captive breeding to increase individuals that are released back into the wild