Slideshow 5 Flashcards
What are two strong predictor for species richness
CLIMATE and PRODUCTIVITY
What was the death rate of the KT extinction
80%
When was the kt extinction
65 million years ago
what percentage of species have been loss since last mass extinction
Up to 50% loss of Earth’s current species
What are some causes of current day extinction
habitat destruction | over harvesting | invasive species | eutrophication |
global climate change | other anthropogenic (human) effects)
What is the drought resistance experiment
Link between species richness and ecosystem function. Diversity of community decreased with addition of fertilizer
What is the ECOTRON experiment
Manipulated species richness in small replicated ecosystems- 14 Controlled environmental chambers
What was the result of the ECOTRON experiment
High diversity communities
consumed more CO2
2. High diversity resulted in
greater primary productivity
What are the 4 main compents affected by biodiversity
- PRODUCTIVITY
- NUTRIENT USE AND NUTRIENT RETENTION
- COMMUNITY AND ECOSYSTEM STABILITY
- INVASIBILITY
How was the question “ Does higher diversity lead to higher productivity?” tested
Cedar creek and Biodepth experiment and Jena
What were the findings of Does higher diversity lead to higher productivity?
Increasing species diversity increases biomass production in primary producers
(terrestrial / freshwater/ marine) - polyculture attains x1.4 biomass vs. monoculture
What is the underlying mechanism between diversity-productivity relationship
NICHE COMPLEMENTARITY VERSUS SPECIES SELECTION
What is niche complementary
Species differ in the use of limiting resources
e.g. phenology, physiology, rooting depths, nutrient requirements
What is species selection
If community contains more productive species
and these dominate overall species richness –
naturally increase productivity
What is complementary effect
presence of nitrogen fixing legumes - increase growth rates of
non-nitrogen fixing species
what were the 3 key factors of diversity and stability
Simple theorem – more species buffers communities against :
(i)
Species extinctions
(ii) Species invasions
(iii) Environmental perturbations
How is stability measured ( Formula)
Stability= Total abundance/ SPECIES LEVEL:
Mean abundance / Standard deviation of its abundance (SD)
COMMUNITY LEVEL:
requires variance (SD) and covariance
What is the overall results of diversity and stability
DIVERSITY HAD A STRONG POSITIVE EFFECT on TEMPORAL STABILITY at the
plant community level
BUT a NEGATIVE EFFECT when considering at the individual level
DIVERSITY AND INVASIBILITY
Are more diverse communities more resistant to invasion by exotic species
