#11 Plant Community Flashcards
What is a “community” and what type of concept is it?
A group of species that occupy a given area
- it is a spatial concept
- a similarity among members of the community
What is an association?
a type of community with relatively consistent species composition and a uniform appearance.
Terrestrial vertical structure is determined by the ______?
life form of plants (size, branching, and leaves) which are influenced by the vertical gradient of light
what are the four layers of the terrestrial vertical structure
The upper layer (canopy) is the primary site of energy fixation
- the understory (under the canopy) will only form if enough sunlight can reach the lower layers
- the herb layer depends on various abiotic conditions (moisture) and density of the canopy and understory
- the forest floor is where decomposition takes place
the distribution of plants and animals into specific zones or regions, each characterized by its dominant species is referred to as?
zonation: influenced by altitude, depth, termperature, and salinity
Define Species Richness (S)
The number of species occuring within the community
Define Relative Abundance
The percentage of species contributing to the total number of individuals of all species (the number of species 1 species/total population
What is Species Evenness?
Indicates the distribution of species richness. Greater species evenness would have a more gradual slope of the rank-abundance curve
When a single, or few species predominate within a community, these species are reffered to as? How would these species fair under prevailing environmental conditions?
Dominants - can reflect the number or size, or both of individuals. Dominant species are typically the dominant competitors under prevailing environmental conditions.
Define Succession
the gradual and directional change in community structure over time
- think of the wolf-sheep lab experiment
The sequence of communities from grass to shrub is called a _____?
- sere
- The series of successional stages on a given site that lead to a terminal community.
Patterns of succession are random (true or false)
False - specific traits and environmental conditions demonstrate success.
Pioneer Species are also referred to as ______? They are characterized by?
Early successional species.
- high growth rates
- smaller seed size and high degree of dispersal
- high rates of population growth
Characteristics of late successional species
- low rate of dispersal
- slower per capita growth rate
- larger species and seeds, live longer than pioneer species
Primary Succession vs Secondary Succession
Primary occurs on a site previously unoccupied by a community
Secondary occurs on a previously vegetated site after disturbance