Threats to Biodiversity

Question 1

What are the threats to biodiversity

Answer 1

• Land use change (number 1 issue)
• Natural resource extraction (number 2 issue)
• Climate change (number 3 issue)
• Pollution
• Invasive alien species

Question 2

Land Use change

Answer 2

• Main driver of habitat loss and biodiversity loss
• Deforestation, mining
• Changes in land management - e.g. intensification of land use in managed landscapes
• Fragmentation of habitats
• Habitat loss and fragmentation THE major driver of biodiversity loss in terrestrial and freshwater ecosystems

Question 3

Velocity of climate change

Answer 3

• Locations where species need high migration rates to keep pace with climate change
• High temporal and low spatial gradient

Question 4

Can we already see direct evidence of climate-induced migration?

Answer 4

• Yes in the Andean forests are becoming increasingly dominated by warm-affiliated tree species
• Tree species are effectively migrating upslope
• If the whole geographic distrubution falls outside of the climate niche of species - extinction (without migration)

Question 5

Climate change and land use change

Answer 5

• Habitat fragmentation has direct effects on biodiversity - e.g. isolating populations, interbreeding
• Migration of species to keep pace with climate change reduced through fragmented landscape - increase risk from CC

Question 6

Climate change effects on Marine ecosystems

Answer 6

• Doesn’t just affect temperature - other effects of anthropogenic climate change (environment change)
• In global oceans, acidification will be a major driver of extinction and biodiversity loss

Question 7

Pollution: Nitrogen deposition

Answer 7

• NO2 and NH3 released by human activities
• Eventually deposited on the land surface
• Major driver of biodiversity loss in terrestrial, freshwater and marine ecosystems
• N is a limiting factor for plant growth, N addition may benefit species adapted to plentiful N + impact on low nutrient specialist
• SR highest where N deposition lowest

Question 8

Pollution: Marine and freshwater ecosystems

Answer 8

• N and or P added to aquatic environment - allows massive algal blooms two main effects.
  1. Toxic Algae - directly kill other species
  2. Anoxia - Increased flux of dead organic material into the water column leads to rapid depletion of dissolved oxygen

Question 9

Alien invasive species

Answer 9

• Key drivers of biodiversity loss
• Various mechanisms e.g.
  1. direct competition with native species
  2. Predation, pests, pathogens
  3. Modifying habitat
  Factors influencing the risk from AIS
• Risk of introduction
• Risk of establishment
• Vulnerability of existing communities