Lecture 8 -- Communities, Successsion and Species Interactions Flashcards
What is the difference between structure and process?
Structure: patterns that we can easily observe in ecosytems- biotic and physical patterns. Vegetation zones, species list, seasonal distribution of activity, different associations of species, variation in sizes and ages of trees, sinuosity of river channels
Process: give rise to pattern- flow regime, herbivory, competition, predation rate, nutrient availability, fire disturbance, decomposition, energy flow, erosion, site history, evolution
Which is structure and which is process: the seasonal pattern in growth of forest understory plants, and light competition.
The seasonal pattern in growth of forest understory plants is an example of structure, light competition is process
Which is structure and which is process: summer low flows in rivers, and the zonation of plant species in estuaries caused by different salinity tolerance levels.
Summer flows is a process, zonation is a structure
Which of the following two characteristics of a community would be considered an “emergent” characteristic, and why? the amount of total annual precipitation that falls as snow, and the amount of total precipitation that infiltrates the soil
Emergent properties result from the interaction of the species with each other and with the environment
Total amount that infilttrates the snow is an emerging characteristic
What is
Mutualism: Competition: Amensalism: Commensalism: Antagonism:
Mutualism: Both benefit from interaction
Competition: neither benefit
Amensalism: When one species is negatively affected, but the other is not impacted
Commensalism: One benefits, the other is not affected
Antagonism: One is negatively affected, one is positively affected
Consider two different forests, both of which occupy the same kind of physical environment. One has an overstory of 50 year old Douglas Fir. The other is also 50 years old but has an overstory that is a mix of 3 conifer and 2 deciduous tree species. Describe how these forests may differ in terms of spatial and temporal structure. Which forest is likely to support more species of small mammals and give at least three reasons why?
Spatial structure is the way species are distributed relative to each other. The more complex the structure, the more diversity that can be supported. The mixed forest would be more diverse, so it has more opportunities to specialize, avoid competition, and hide from predators
Temporal structure is the timing of the appearance and activity of species. The mixed forest would have annual species, driven by light.
What is ecological succession?
Change in species over time
- often initiated by disturbance or environmental change
- often occurs because each set of species alters the environment, which facilitates the establishment of new species
How could the removal of wolves and mountain lions from a landscape result in widespread disturbance to the forest understory community?
WIthout predators, primary consumers become overpopulated and can destroy their habitat
Describe two factors that affect the path and outcome of succession.
Legacies: what species are left after a disturbance
Dispersal abilties: who can get there first
What’s the difference between primary and secondary succession?
Primary succession: the sequence of species on newly exposed landforms that have not been previously influenced by a community. No legacy.
Secondary succession: vegetation has been partially or completely destroyed, but some soil, plants, seeds, and spores remain. There’s a legacy to jumpstart recovery.
Describe how sea otters affect the spatial structure of kelp forests and why this makes them a keystone species.
Keystone species act to maintain or increase diversity. Otters eat urchins, which prevent them from over running kelp forests.
What’s the difference between a fundamental and realized niche?
Fundamental: resources/habitat an organism could theoretically use in ideal conditions
Realized: resources/habitat it actually uses (more restricted by competition, predation, etc.)
Give an example of competitive exclusion. Same for resource partitioning.
Competitive Exclusion: You eat your competition!
Resource Partitioning: Adapting to utilize different resources so there isn’t any competition (warblers)
Several species of warblers that all eat small insects on trees can coexist in a forest. How do they do it and what is the term for their tactic?
They live in different sections (heights) of the trees so they don’t cross or compete. It is called resource partitioning!
Several species of salmon can occupy the same river. Describe how they can coexist and what is a term that describes their tactics?
They coexist because they use the same river at different times! they have adapted to temporal timing stuff… partitioning.
