Community Ecology

Question 1

What is a community?

Answer 1

• All organisms living in particular place
• spatially explicit
• very complex to study: the more you look the more you find
• so often restricted to subset of organisms

Question 2

Main aims of community ecology

Answer 2

explaining/predicting species distributions and abundance

• across time and space
• abiotic and biotic factors affecting
• underlying mechanisms

Quantifying patterns and looking for results
- e.g. species-area relationships

Dynamics of communities and response to disturbance

Question 3

Why is community ecology research important?

Answer 3

• habitat management, conservation and restoration
• classification, bio monitoring an. Diagnostics
  E.g. NVC samples vegetation communities across UK

Question 4

Criticism of community concept

Answer 4

2008: Ricklefs
- most research single scale = local community
- assumes closed area w/ arbitrary boundaries
- what’s easy for ecologists rather than what’s actually happening real world

Question 5

Meta population

Answer 5

Different species have discrete populations that have connectedness between other populations within an area

Question 6

Properties of describing a community

Answer 6

Abundance distributions
Evenness and dominance
Richness
Composition

Question 7

Rank abundance plots

Answer 7

Allows comparisons between species’ in a community
- rank species by abundance
- convert abundance into relative abundance (added together = 1)
Create plot
X = species rank
Y = relative abundance

Can overlay pots to compare communities

Question 8

Evenness and dominance

Answer 8

• how total abundance is distributed among species
• more even = more diverse
  Many diversity indices e.g. Shannon-wiener combine evenness with species richness
  Use simpsons index

Question 9

Richness

Answer 9

Number of species in a community

• number of species is selective to sampling methods (more effort means you find more)
• more studies have a species density = within a set boundary e.g. quadrant
• can use computer program to estimate how many individs you need to get best results. Compare to real results to see how well you have done

Question 10

The problem with determining richness

Answer 10

• most species in a community are low in abundance = low detection probability
• hard to separate the role of sampling technique and abundance…is there an increase in species or is technique just better?

Question 11

Composition

Answer 11

Can use:
- species list 
- bio assessment metrics e.g. RIVPACS
- classification and ordination 
- ecological traits; alternative to taxonomy, grouping species and summarising communities using ecological characteristics e.g. predators, filter feeders, parasites 
Results may be more informative

Question 12

Comparing communities

Answer 12

Plot communities on scatter plot, showing similarities and differences in abundance between communities
- distance between pots = measure of similarity
- create distance matrix using computer
0 = identical
1 = no species

Ordination analysis: samples ordered based on similarities