What is ecosystem functioning?
An umbrella term for the processes operating in an ecosystem, ie biogeochemical flows of energy and matter within and between ecosystems.
What is biodiversity?
A contraction of biological diversity that encompasses all biological variation from the level of genes through populations, species and functional groups (and sometimes higher levels such as landscape units).
What is complementarity effect?
The influence that combinations of species have on ecosystem functioning as a consequence of their interactions. (e.g., resource partitioning, facilitation, reduced natural enemy impacts in diverse communities)
What are ecosystem processes?
The biogeochemical flows of energy and matter within and between ecosystems, eg primary production and nutrient cycling.
What is an ecosystem service?
An ecosystem process or property that is beneficial to humans, eg provision of food, CO2 sinks.
What are selection effects?
The influence that species have on ecosystem functioning simply through their species- specific traits and their relative abundance in a com- munity (positive selection effects occur when species with higher-than-average monoculture performance dominate communities)
What are the approaches that can be taken to determine the relationship between biodiversity and ecosystem functioning?
- Direct manipulation of biodiversity by the assembly of synthetic model communities in the lab or the field.
- Remove species from natural communities.
- Infer the relationship by seeing how these two are correlated across habitats.
What is the relationship between biodiversity and ecosystem functioning?
Meta-analysis of the first decade of research clearly shows a positive relationship between biodiversity and ecosystem functioning, a pattern that is remarkably consistent across trophic groups (produc- ers, herbivores, detrivores, and predators) and present in both terrestrial and marine ecosystems. However, the relationship between biodiversity and ecosystem functioning is generally saturating, suggesting that the effect of random biodiversity loss on ecosystem func- tioning will be initially weak but will accelerate. Another result is that species and species assemblages have varying impact on functioning. There has been debate about whether this is caused by complementarity effects or selection effects.
Is the effect of biodiversity on ecosystem functioning caused by complementarity effects or selection effects? What does this imply about the comparison of the performance of diverse communities and monocultures?
- 1. In summary, although the relation- ship between biodiversity and ecosystem functioning is positive, complementarity effects contribute ap- proximately twice as much as selection effects in gen- erating these relationships,
- 2. diverse communities do not generally perform better than the best individ- ual species.
- 3. However, this result is influenced by the short duration of many of the experiments performed to date because the relationship between biodiversity and ecosystem functioning grows stronger over time (figure 3) as a result of increasing complementarity. Nevertheless, it appears that diverse communities are rarely able to do substantially better than a monocul- ture of the best-performing species that they contain. This also appears in part because communities are also often dominated by species that have lower productivity, leading to negative selection effects.
What are ecosystem services? How are they affected by loss of biodiversity?
- Loss of biodiversity leads to decreased ecosystem services.
- Provisioning of materials
- Cultural and psycho-spiritual well being
- Supporting services (nutrient cycling, soil formation)
- Regulating services (pollination, climate regulation, pest and disease control etc.)
How does biodiversity affect ecosystem stability?
- One possible value of biodiversity to humans is its potential to in- crease stability by buffering ecosystem processes such as production against environmental variation and mak- ing them more resistant and resilient to perturbations.
- In summary, evidence from both natural and experimental systems of plants and microbes suggests that insurance effects of biodiversity on temporal stability may be relatively widespread.
- Additionally, asynchronous population fluctuations buffer total community biomass. Thus, communities with greater species richness tend to be more stable.
What is the implication of a lack of regard for ecosystem multifunctionality in past analyses (ecosystem interactions) on the amount of biodiversity required to maintain overall ecosystem functioning?
This implies that a higher biodiversity is required than those calculated by individual ecosystem processes in isolation.
What are the two views regarding the motivations for the conservation of biodiversity?
- Bio/Eco-centric: Intrinsic value of biodiversity, consequences of a lack of conservation for the sustainability of communities and ecosystems.
- Anthropocentric: Practical consequences of the loss of diversity for humans.
Which human activities primarily result in a loss of biological diversity?
- Development, resource extraction, land conversion
- Fire suppression
- Movement of biota (invasive species)
- Trophic downgrading (the removal of large apex predators leads to top-down effects.)
What are the characteristics of anthropogenic biodiversity loss?
- Not random: large apex predators are especially susceptible
- Up to 2,000 extinctions a year (up to 10,000 times natural rate)
- Characterizes the early-middle stages of the 6th mass extinction.
Briefly explain the changes in Finger lakes plant diversity in the past 200 years.
Around 1200 native plant species are in the area alongside 600 non-native species. There haven’t been any extinctions. It is unclear how representative this is of extinctions as a whole, as extinctions at higher trophic levels and in other places are rampant (such as the tropics)
Explain Elton’s theory.
Simpler communities are less resilient than rich communities, in that they are more subject to destructive oscillations in populations and more vulnerable to invasions.
What were the three main observations regarding the positive community outcomes of biodiversity (consequences of species diversity)?
- Diverse crop mixtures are more productive than monocultures.
- Pest outbreaks often occur in crop monocultures and are a feature of temperate but not of tropical forests.
- Small islands (less species diversity) are more prone to species invasion.
What are the mechanisms that maintain local diversity?
- Top-down effects (predation)
- Bottom-up effects (resource availability)
- Resource partitioning. (narrower resource partitioning allows for greater species packing)
- Microhabitat partitioning
- Food type partitioning
- Temporal partitioning
What are the three different types of diversity?
- Richness vs. evenness
- Spatial scale of diversity (alpha-gamma-beta)
- Taxonomic scales of diversity
- Functional groups (animal guilds, C3, C4, woody, legumes etc.) / among species
- Phylogenetic (among species)
- Genotype (within species)
Explain the concept of complementarity and the link between diversity and function.
As diversity increases, there will be greater community / ecosystem function, often through greater resource use.
What are the positive effects of biodiversity?
- Drought resistance
- Primary production (biomass)
- Resistance to invasion
- Crop protection
How do the impacts of genetic diversity compare to the effects of other levels of diversity?
Theoretically, genotypic diversity is expected to have less of an effect as species have larger differences than genotypes. Therefore, genetic diversity may provide less complementarity than species diversity.
What are the reasons behind the positive effects of diversity?
- Insurance effect: different species / genotypes do better under different conditions.
- Negative covariance effect: under stressful conditions, when one species / genotype suffers, others do well (disturbances are not as detrimental to the entire system as they could be; losses in one species are offset by the gains of another. Over time there is averaging. )
- Emergent / interaction effects: those benefits of diversity that cannot be predicted by species traits, but emerge from diversity per se, or interactions among species.