Fill in the blanks for lecture 4 Flashcards
Stressors include what? (4)
Habitat loss, invasive species, climate change, overharvesting
Ecosystem functions are what?
Stocks and fluxes of energy and materials (ex: biomass, productivity, nutrient cycling), stability, invasibility
Biodiversity ecosystem function hypothesis (BDEF): a reduction in biological diversity (variety of species, genotypes, ect.) will cause a _______ __ ________ _____ _________.
reduction in ecosystem level processes
There are 3 classes of BDEF hypotheses:
1) Species are primarily ______
- loss of species is ___________ for by other species; or, the addition of such species adds nothing new
Redundant; compensated
Redundant species: a species could be lost “without much effect on the ______ ___ ______ of the whole community.
structure and function
3 classes of BDEF hypotheses:
2) Species are primarily ________
- Species contribute to ecosystem functioning in _______ ____, their loss or addition causes detectable changes.
unique ways
What are keystone speices?
A species on which other species in an ecosystem largely depend, such that if it were removed the ecosystem would change drastically.
Keystone species are most attributable to which class of BDEF hypothesis?
2) Species are primarily singular
3 classes of BDEF hypotheses:
3) Species impacts are context-dependent and therefore ___________.
- The impact of loss or addition of a species depends on ______ _________. (ex: composition)
unpredictable; local conditions
Assumptions of BDEF:
1) _______ is changed at a scale relevant to ecosystem functions
diversity
Assumptions of BDEF:
2) Reductions in commonly measured ecosystem variables are ___________.
undesirable
Ecosystem functioning is divided into 3 classes:
1) Stocks of _______ and ________ (ex: biomass)
2) ______ of energy or material processing (ex: productivity, decomposition, nutrient cycling)
3) ________ of rates or stocks over time (ex: invasion resistance)
1) energy and materials
2) Fluxes
3) Stability
What are the different properties of stability?
Resilience, resistance, robustness, persistence.
_________ - a measure of the speed at which an ecosystem returns to its original state after a disturbance.
resilience
_________ - a measure of the degree of disturbance a system can withstand before switching to another state.
robustness
__________ - a measure of the ability of a system to maintain itself through time.
Persistence
________ - a measure of the ability of a system to maintain its original state in the face of a disturbance.
resistance
Diversity and stability: communities with more species are buffered against:
1) _________
2) ________
3) _________ __________
1) extinctions
2) invasions
3) environmental perturbations
__________ effect: explains why more diverse systems are more stable.
portfolio effect
The portfolio effect can be described as:
A broadly diverse portfolio _____ less over time (y) than if you invested only 1 or 2 stocks.
As you average more stocks (or more species), they become _____ variable.
Nature, like a stock, has _____ and ____ years.
1) varies
2) less
3) good;bad
Ecosystem stability: treatment plots with _____ diversity were 70% more stable in biomass production than __________.
high; monocultures
______ ___________: niche differentiation between species or genotypes allows for more efficient exploitation of resources.
niche complementarity
Examples of niche complementarity (i.e. lack of niche overlap) are?
Utilization of the same resource differently, foraging in different ways, use different life stages of prey, use different part of the plant (resource).
________ ______: species that are redundant in functional roles or capacity respond differently to stressors.
Insurance effects
niche complementarity hypothesis: combinations of species that differ in _______ ___ (low niche overlap) have greater impact on ecosystem function.
Resource use
When species niche overlap is low, expect ______ differences in ecosystem functioning.
large
Evidence for niche complementarity:
1) ______ ________
2) ______ relationship between species richness and ecosystem functioning
1) transgressive overyielding
2) positive
_______ _____________ plays a role in the way algal species diversity improves water quality (via nitrate uptake).
niche complementarity
Ecosystems with ______ _______ are more efficient at removing nutrients from soil and water than ecosystems with _______ ________.
more species; fewer species
_______ habitats: more niche opportunities for species to coexist.
heterogeneous
Streams with heterogeneous habitats allow ________ _________ among algal species.
resource partitioning
A single species becomes dominant in ___________ habitats.
homogeneous
Mechanisms that stabilize ecosystem functions via increased diversity:
_______ _________ can stabilize communities through omnivory or the buffering of strong interactions by weak interactions.
_____ _____ ______ ______ tend to stabilize food webs and characterize more diverse communities.
1) multitrophic interactions
2) low mean interaction strengths
Monoculture:
_______ environment for many natural enemies.
Has been suggested that by ________ plant diversity, natural enemy numbers will ________ with a corresponding ________ in herbivore numbers.
1) hostile
2) increasing; increase; decrease
What is this bitche’s favourite model organism?
Dicyphus hesperus
________ design: species densities are constant across treatments.
substitutive
Temporal stability of individual species populations: equation?
S(i) = u(i) (mu)/sigma(i)
mu(i) is the mean abundance of species i
sigma(i) is its temporal standard deviation
Individuals species show higher stability in _________ than in ________.
polyculture; monoculture
Overall, ________ shows an increase in stability relative to __________.
polyculture; monoculture
Conclusions (Brommit et al.)
1) Herbivore population stability ________ with increased diversity
2) Specialist parasitoid population stability ______ with increased diversity
3) omnivore population stability _______ with increased diversity
thus,
4)
increases for the 1-3
4) each trophic level stability increases with plant diversity
______ ________ increases withe the number of resident species.
biotic resistance
________ resistance increases with species richness.
invasion
Mechanism: diversity and invasibility (i.e. decrease in invasion success by exogenous plant species)
1) _______ in root biomass
2) ______ in available nitrate in plots
1) increase
2) decrease
