Chapter 3

Question 1

Species richness varies with

Answer 1

PLOC

Productivity
Latitude
Other physical & biological variables
Climate

Question 2

Earth’s species may
disappear due to:
(there are 6)

Answer 2

Habitat destruction

Overharvesting (particularly marine species)

Invasive species

Eutrophication

Global Climate Change

Other Human Activities

Question 3

Naeem et al. (1994) & Tilman and Downing
(1994)

Answer 3

Two studies that paved the way to understand the relationships between
biodiversity and ecosystem functioning.

• see slides

Question 4

effects of
biodiversity on four important ecosystem
functions: which are
“pinc”

Answer 4

Productivity
Invasibility
Nutrient use and nutrient retention
Community and ecosystem stability

Question 5

Species richness had a strong, positive effect on

Answer 5

primary productivity

Question 6

slide 19 not sure how to break up

Question 7

Increasing species richness increases

Answer 7

biomass production in primary
producers.

Question 8

question: Does higher species diversity lead to higher ecosystem
productivity?

Answer 8

For at least low-stature plant communities… YES!

Question 9

A recent meta-analysis of 368 experiments found that manipulated primary
producers in a variety of ecosystems (i.e. terrestrial, freshwater, marine)
resulted in an increase in biomass when high plant species richness occurred.

But, some mathematical modeling has found that although the relationship is
positive,

Answer 9

it occurs at a decelerating rate. (diminishing returns)

Question 10

Why might productivity increase with species richness?

Answer 10

two mech
Niche complementarity

Species selection

Question 11

what is niche complementarity

Answer 11

When species differ in the way they
use limited resources.

If each species differs in their
niches, the use of resources within a
community becomes more efficient
and this can leader to higher
productivity.

Question 12

what is species selection

Answer 12

Species Selection (a.k.a. sampling effect)

May lead to increased productivity with increased species richness if diverse
communities are more likely to contain more productive species that come to
dominate the community.

Question 13

is the relationship between the extent of ecosystem
functioning and the degree of niche overlap between species npositive or negative ?

Answer 13

negative

Question 14

Meta analyses

Question 15

If species exhibit resource partitioning and niche complementarity, then

Answer 15

more diverse communities should use resources more efficiently and the
amount of unused resource in an ecosystem should decline as species
richness increases.

Question 16

Most data in support of niche complementarity
comes from

Answer 16

terrestrial plants.

Question 17

nitrogen availability limits

Answer 17

primary productivity.

Question 18

Nitrogen
in above ground vegetation also correlated

Answer 18

positively with species diversity.
This means N uptake increased with increasing plant diversity.

Question 19

Dijkstra et al. (2007)
an
increase in plant species richness reduced

Answer 19

that an
increase in plant species richness reduced leaching loss of dissolved inorganic nitrogen.

Question 20

Cardinale et al. 2011
on polycultures

Answer 20

Found that species-rich polycultures reduced nutrient concentrations (mean
= 48%) more than monocultures

Little evidence that polycultures used resources more efficiently; standing
nutrient concentrations in soil/water were higher in polycultures than the
most efficient monocultures

Question 21

Do polycultures use resources more efficiently
than the most efficient monocultures?

Answer 21

They Uptake it, but do they use it efficiently?

Simple Answer: it depends on the complexity

homogenous vs heterogeneous

biomass plays a role

heterogeneous streams increased algal richness dramatically reduced the
amount of dissolved nitrogen.

by increasing algal species richness in heterogeneous streams, water quality
was significantly increased due to niche complementarity.

Question 22

Temporal Stability

Answer 22

Examines species abundance (usually measured in biomass) over time

Diversity had a strong, positive effect on the temporal stability of the total
plant community, but a negative effect on the stability of individual species
abundances.

Question 23

The idea that increased species diversity leads to ecosystem stability has been
around a long time!
but does it

Answer 23

The answer seems to rest on how we view
stability.

Question 24

Are more diverse communities more resistant to invasion by exotic species?

Answer 24

Overall, yes, but there are some important unanswered questions.
Elton (1958): “This resistance to newcomers can be observed in established
kinds of vegetation, due to competition for light and soil chemicals and
space.”

Fargione and Tilman (2005) – again using the Cedar Creek plots – found
both biomass and number of invading plants declined as richness of resident
plant community increased.

Question 25

Increasing biodiversity negatively affects

Answer 25

invaders ability to survive

Question 26

decreasing occupied space

Answer 26

decreases native species richness?

Question 27

What traits make it more likely for species to go extinct?

Answer 27

strong, consistent effects of biodiversity loss on ecosystem functionality

Loss of particular species can significantly impact ecosystem functioning (keystone species)

Some traits such as population size, geographic range, body size, trophic level, low
fecundity can accurately predict probability of loss for some species.

Question 28

How has biodiversity been affected by human activities?

Answer 28

It seems species richness can stay the same, but species turnover has risen in areas of high
human impact (i.e. invasive species taking over native species) - Thus, Beta diversity is high
while Alpha diversity remains similar.

Still need to better understand effects of species richness on ecosystem functioning

Question 29

How do multiple interacting trophic levels
impact biodiversity?

Answer 29

trophic-level interactions are important for
ecosystem functioning

alterations in the number & kinds of top-level
consumers have cascading effects

number of species declines as we move from lower
to higher trophic levels, species extinctions tend to
occur towards the top
think pyramid

Question 30

Why do areas of high native plant diversity also contain high numbers of
invading plant species when experimental manipulations find the opposite?

Answer 30

Hypothesis to address this:

Environmental factors that support high native plant diversity also support high exotic
plant diversity. Small-scale experiments seek to control environmental variation.

Question 31

Experimental evidence overwhelming finds that biodiversity alterations
significantly impact ecosystem functioning, but some have questioned if
that impact in natural ecosystems is significant.

Answer 31

Here again we are seeing the pull between experimental data and what actually occurs
in natural systems.

Question 32

Species richness varies with

Answer 32

Latitude

Climate

Productivity

Other physical & biological variables

Question 33

what was biomass a measure of

Answer 33

productivity

Question 34

Tilman and Downing (1994)

Answer 34

Showed a link between species richness, ecosystem
productivity, and ecosystem stability

Found that plots with high plant species diversity
were better buffered against the effects of a severe
drought.

Question 35

four important ecosystem
functions:

Answer 35

Productivity

Nutrient use and nutrient retention

Community and ecosystem stability

Invasibility

Question 36

‘Jena Biodiversity Experiment’

Answer 36

study above- and belowground productivity and nutrient use
efficiency.

Question 37

Species richness had a strong, —— effect on primary producers

Answer 37

positive

Question 38

Cedar Creek productivity (measured in biomass) increased rapidly in response to
the addition of a few plant species, but then

Answer 38

slowed (reached diminishing returns).

Question 39

Positive effect of species richness on plant biomass….

Answer 39

increased over time.

Question 40

how does increasing species richness affect biomass production in primary producers

Answer 40

Increasing species richness increases biomass production in primary
producers.

the relationship is
positive, it occurs at a decelerating rate. (diminishing returns)

Question 40

richness-biomass relationship, and functional group richness-biomass relationship have _______ correlations

Answer 40

Positive

Question 41

Two mechanisms productivity increase with species richness?

Answer 41

Niche complementarity

Species selection

Question 42

Niche complementarity

Answer 42

If each species differs in their
niches, the use of resources within a
community becomes more efficient
and this can leader to higher
productivity.

Question 43

Species Selection (a.k.a. sampling effect)

Answer 43

May lead to increased productivity with increased species richness if diverse
communities are more likely to contain more productive species that come to
dominate the community.

Question 44

Transgressive overyielding

Answer 44

plots containing species mixtures yield more
biomass than any monoculture plot.

Question 45

when does species selection tend to be dominant vs ncihe complementarity

Answer 45

Studies of terrestrial plant communities
suggest that species selection effects are
the dominant drivers of ecosystem
functioning EARLY in experiments

Niche complementarity effects
become stronger as communities
mature.