Week 3 & 4 Flashcards
(73 cards)
Plants growing in tropical ecosystems have, on average, much higher N:P ratios than plants growing in high-latitude ecosystems. Why?
Ecosystems in the tropics are older
Feedbacks in disturbance regime and matter & energy cycles
- Linear vs non-linear trends
- Feedback systems keep you in the same ecosystem for a long time
» If you have strong feedbacks, you don’t see any change in a community until it suddenly changes to an alternative stable change
» The more resistant communities have a high feedback loop and that causes unpredictability (it looks like nothing is happening and then there’s a sudden big change)
Alternative stable states
- It occurs when in the exact same environmental conditions there are two completely different ecosystems
» E.g., the soil is the same, climate is the same, but you can find different ecosystems like grasslands and forests - There is a positive feedback loop going on in each of the states
- Because the different states have feedback loops going on they can co-exist next to each other (e.g., grasslands and forests coexisting)
True or False: SE-AS framework was developed in response to the following critique of the SES framework in the study of social-ecological systems. “The SES framework requires a more explicit incorporation of ecological attributes”
True
(explaination: One of the main contributions of the SE-AS framework is its further unpacking of the interactions within an action situation. Rather than purely social interaction (i.e. the S-AS), they include other types of interactions between human and non-human entities. In this way, it draws focus to these ecological attributes in the study of SES)
True or False:
During succession the vegetation biomass generally decreases.
False
What is the redfield ratio?
- He traveled all across the ocean and took samples everywhere from the phytoplankton
- Compared C : N : P ratio and found that they are all the same: most of these phytoplankton have 106:16:1 (106 carbon relative to 16 nitrogen relative to 1 phosphorus)
- The N : P ratio is similar to the ideal, which signifies that there is some kind of rule that plants need about 16 times nitrogen relative to phosphorus (for optimal growth)
During succession, when do we see higher amounts of nitrogen? Phosphorus? Why?
- At the beginning of a succession there is a lot of phosphorus, which is also mainly found in the ground/soil
- Nitrogen on the other hand comes from the air and has to be fixated by the plants in order to use it (fixation takes time and then builds up in the system)
- In late successional stages there is usually more nitrogen than early successional stages
The relationship between species richness and ecosystem functioning generally follows the shape of which hypothesis?
Redundant hypothesis
The study of SES requires focusing on two key subsystems - the social and ecological subsystem. Their relationship is characterized by 2 features–what are they?
Coupled subsystems & interacting subsystems
Which process can be reduced by large herbivores? Why?
Competitive exclusion; when herbivores eat certain plant species, there is less competition amongst them
True or false:
Silvia & McGuire’s study shows that task-oriented leadership is more important in collaborations, compared to single organizational settings
False
True or false:
Silvia & McGuire’s main argument that leadership in collaborations is different, is that within networks there is not one hierarchical ‘boss’ who can give orders or fire other stakeholders.
True
Which of the following elements does not have a gaseous phase? Carbon, nitrogen, hydrogen, phosphorus
Phosphorus
What are some things we can assume about this graph?
- Fragmentation reduces biodiversity by up to 75%
- the effects of fragmentation are greatest in smallest and most isolated fragments
reduced areas - species area relationship (SAR)
SAR = the relationship between the area of a habitat, or part of a habitat, and the number of species found within that area
- The smaller the area you have, the less species richness there is
Limiting factors
- habitat heterogeneity
- speciation
- fragmentation
- dispersal
True or false:
SAR refers to the relationship between the number of species and the size of the land.
True
What is habitat heterogeneity
It is one of the factors that can impact SAR and is the variation of physical characteristics of a specific habitat, including weather, vegetation, and soil
What are some of the important variables in regard to increased isolation/fragmentation?
- size of the fragments
- distance between the fragments
- proportion of edge habitat
Explain the relationship between habitat fragment size and the edge effects, as shown in the image
as fragment size increases the relative proportion of edge habitat decreases, and interior habitat increases
Explain meta-populations (in regard to habitat frag)
A meta population is a “Population of populations” (Levins, 1967) on a patchwork of “suitable” habitat within a non-suitable matrix, interconnected by limited dispersal.
What are some of the characteristics of meta-population?
- Frequent local extinctions
- Long-term survival of the
metapopulation is dependent on
colonization through local
dispersal.
In terms of habitat fragmentation, what do we mean by connectivity?
- Distance from all the other occupied patches
- Area/Size of those occupied patches
- Dispersal distance of any given species (i.e. dandelion seeds vs. stone fruits)
Source vs sink (in regard to meta-populations)
→ Source: subpopulations with positive growth rates; they act as sources (individuals disperse from there to other subpopulations, including the sink subpopulations)
→ Sink: subpopulations with negative
growth rates (in absence of dispersal)