L6 Synecology Flashcards
What effect does sepentine soil have on the boundaries between plant communities
Creates more abrupt boundaries and lack of ecotones
What does serpentine soil contain lots of
Heavy metals
What are ecotones
Transitional areas - the gradual blending of two communities
What effect do humans have on the boundaries between vegetation
Humans also cause abrupt boundaries
Plants are only a subset of the community, what other subsets are there
Herbivory
Disease
Pollinators
Mycorrhizal associations
Define plant community
The collection of plant species growing together in a particular location that show a definite assocation or affinity with each other
How many recognised plant communities are there in the UK
286
How are oundaries of plant communities defined
Based on changes in abundance of dominant or common species
When sampling a plant comunity, which areas should be avouded
The edges / near the boundaries
What is a stand in terms of sampling
Local area treated as a unit for the purpose of describing begetation
What are the 2 questions that arise in sampling the plant community
How large should the area be?
Where (precisely) should the sample be?
What are 2 ways quadrats could be assigned a location
Subjective - positioning in ‘typical vegetation’
Objective - positioning by randomisation
What was Clements view of the plant community
Superorganismic, holistic view of ocmmunity structure
What was Clements view of the plant community
Superorganismic, holistic view of ocmmunity structure
What was Gleasons view on the plant community
Individualistic, reductionist
What are the 2 main differences in Clemets and Gleasons arguments
The importance ascribed to biotic versus abiotic factors
The predictable versus unpredicatble pprocesses
Who of Gleason and Clements is more likely correct
Where is the modern view
Gleason more likely correct
Modern view is somewhere in the middle
Where did Clements study
North America
What is the climax community in the UK
Temperate woodland
What did Clements believe was responsible for the nature of the climax community
Climate
Clemets believed that the life history of a community was…
A definite and predictable process
What did Clemets believe was the singular factoe determining community structure
Only species interactions
How did Clements break up commuities in North America
How many climax communities did he recongise
What were they
What were they divided into
What were these further divided into
Recognised 3 climax communities
Grassland, scrub and forest
Subdivided into formations
Further subdivided into associations
What is the modern name given to what Clements identified as ‘associations’
= communities
What 3 things did Gleason believed formed the individualistic community
The result of interactions between individual species and the environment (biotic and abiotic)
In combination with change historical events
What 2 things did Gleason believe were responsible for determining community structure
Biotic and abiotic interactions
What did Gleason believe happened at boundaries between communities
Do all species experience the same boundaries
Different species have different boundaries at different places along an environmental gradient
Changes are gradual, not abrupt transitions
What 4 things did Gleason think could affect heterogeneity of community structure
Accidents of seed dispersal
Minor variations in environment
Different abundances of parent plants
Brevity of periods (length of time) between disturbances
What did Clements believe occured between two plant communities
An abrupt boundary
What did Whittaker belive the pattern was
When was this
What was his theory called
Mosaic climate pattern
1956
Community-unit theory
What kind of gradients did Whittaker belived played a role in establighing forest communities
Elevational gradients
What did Whittaker believe about the transition zones between communities
They were gradual changes, not abrupt transitions
What is succession
The non-seasonal, directional and continuous pattern of colonisation and extinction on a site by species populations
Where does primry succession occur and is it influenced
Occurs on exposed landforms
Uninfluenced by a previous plant community
Who came up with the idea of succession
Clements
What did Clements believe was the end stage of succession
Dynamic equilibrium
How many stages did Clements believe there was to succession
6
Did frequency, strength and complexity of interactions decrease or increase throughout succession
Increase
Define seres
The series of recognisable communities before a climax was achieved
Did Clements believe you could predict the climax community
What would determine the climax community
Yes they are predictable and determined by climate
When does secondary succession occur
When vegetation of an area is removed but soil and seeds or spores remain and a sequence od speciew regenerates
Is primary succession faster or slower than secomndary succession
Primary is slower
What parts of Clements theory did Gleason disagree with
The determinism and directedness
How did Gleason believe communities were established
Random elements of seed immigration and seedling establishment
What did Gleasin believe established the end point of succession in an area
Initial conditions and disturbance histories
Why did Gleason disagree with the consept of an equillibrium community
Communities exhibit transient dynamics
Communities often change and we cannot tell if we are at the end of succession
What did Gleason believe could cause succession
Distrubance
Gaps = large like landslides or local like one tree being struck by lightning
Wind
Water
Earthquakes and volcanoes
Colonisation rates
What did Clements (1916) believe about the end point of succession
Monoclimax theory = in a given climatic refion, a single climax will dominate
What did Tansley (1935) believe about the end point of succession
Polyclimax theory = local climax governed by a combination of factors e.g. Climate, soil conditions, topography, fire
What did Whittaker (1953) believe about the end of succession
Climax pattern hypothesis = continuity of climaxes along environmental gradients
