2: Biodiversity & ecosystem function

Question 1

Biochemical activity on earth determines…

Answer 1

Soil fertility
Air & water quality
Habitability of ecosystems
Climate

Question 2

Describe the redundancy hypothesis

Answer 2

Increases (linear) function as you add species, at some point function reaches a plateau

Question 3

Describe a keystone species

Answer 3

a species that has a disproportionate impact on ecosystem compared to its biomass = sudden huge jump in function

Question 4

Describe Al-Mufti et al. 1977 survey into biomass = function in Sheffield regional vegetation

Answer 4

V low and high biomass has low biodiversity
Intermediate biomass has greatest biodiversity
= Biodiversity-function relationship is a humped-back curve - but filled underneath

Question 5

Describe Alder et al. (2011) global analysis into the Al-Mufti hump-back curve

Answer 5

48 sites globally
Only 1 site showed negative concave (hump-back curve)
Most sites: no biodiversity-biomass relationship within site
Hump-backed curve not applicable to most ecosystems

BUT, update shows the sites do fit the curve, hump-back may apply in an across-ecosystem relationship

Question 6

Define niche complementarity

Answer 6

Species have different ways of functioning, and so increased number of different species increases complementarity

Question 7

Describe Hector et al. (1999) Biodepth experiment

Answer 7

Overall, species loss reduced biomass production (measured over 2 yrs)
Agrees with Naeem et al., 1995 findings
Criticism: short term, immature communities, competition?, disproportionate legume effect
= Loss of biodiversity means less function

Question 8

Describe Naeem et al. (1995)

Answer 8

Growth chamber experiments with created herbaceous communities of different biodiversity
Clear increase in biomass with increasing species
Mechanism: Niche complementarity
Criticism: sampling effect (relationship accidentally created by having more productive plants)
= Biodiversity means more function