diversity changes

Question 1

diversity changes?

Answer 1

opulation declines and extinction of species
6th major extinction

Question 2

how do invasions lead to diversity changes

Answer 2

• Accelerated by humans - transport and travel
  ○ Deliberate or not
  ○ Homogenizes ecosystems

Question 3

functional types? ex?

Answer 3

• Groups of sp that are ecological similar with respect to their effects on ecosystems or their response to environmental change
  ○ Ex. N fixing plants - symbiotic relationships with bacteria
  
  • Important bc fundamentally, diversity is a really hard issue to deal with

Question 4

Ecosystem processes vs effect of species number

Answer 4

• Npp as a function of species richness
  
  • Curved line -where functional groups come into play
  • Effect of adding new species depends on whether they are functionally redundant
  • Tends to be low functional redundancy when species richness is low (more ecosystem roles or functions to fill)
  • Species rich communities have higher functional redundancy (may lead to stability)
  • Ie. Threshold where each species starts to serve a particular function that is not buffered by functional group redundancies

Question 5

dominant vs keystone sp?

Answer 5

• Dominant species - species that are most abundant (or have largest biomass) in a community
  
  • Keystone species- species that, relative to its biomass or abundance, has a disproportionately large impact on community structure
    Minimal impact of rare species in terms of response

Question 6

keystone vs compensating?

Answer 6

• Keystone vs compensating
  
  • The composition of diversity can alter ecosystem processes in different ways

Question 7

invasion ex

Answer 7

• Plant invasive to hawaii
  
  • How nitrogen fixing plant impacted basic ecosystem functions
  • In each graph, where the invasive plant is present,
  • Changing soil dynamics in N
  • Mineralization rate - where there are invasions
  • Hawaii is very vulnerable to invasions as most islands are

Question 8

invasions california ex

Answer 8

• Natural community are bunch grasses
  
  • Arid system - Mediterranean type
  • Opportunity to invade systems due to their functional systems
  • European grass + eucalyptus from australia - invasive in cali
  • Tapping into ground water better by size
  • Eucalyptus oil produced is an issue

Question 9

• Species effect on microclimate
  
  • Ecosystems

Answer 9

heat fluxes from decidous and boreal forest
- look in text

Question 10

ecological services?

Answer 10

• Ecological services - processes and resources of value to humans provided by ecological systems. These processes and resources are typically called ecological functions
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Question 11

ecosystem function

Answer 11

• Ecosystem function - process within an ecosystem such as biomass production, nutrient cycling, or carbon sequestration. If function is diminished, so too is the quality of the service

Question 12

diversity-function relationships
* Ex. Cedar creek

Answer 12

• Experiments in minnesota, fundamental to understanding diversity
  
  • This was the first time the idea of diversity was emperically tested
  • Replication of different levels of diversity + combos of species
  • Could measure what is taking place in the plots
  • Looked at how diversity changed relatively
  • Saturating curve - yield increases over time with more diverse plots being more productive over the 15 yr study

Question 13

• Why increase in productivity with diversity?

Answer 13

○ Three main mechnisms proposed:
§ Complementarity: based on niche theory; highest in ecosystem being most fully exploited
§ Facilitation: some species enhance growth of others
§ Sampling effect: based on the assumption that functions of communities with low species evenness are driven by dominant species
□ Ie. The more species you have, the higher chance the species you pick has higher productivity than if you pick just one species

Question 14

why did nitrate decrease in cedar creek

Answer 14

○ Nitrate decreases bc its being used at a higher rate - nutrient partitioning