The nature of communities

1
The nature of communities

• Ch. 15

2
Objectives

• Defining communities
• Species diversity
• Classification based on species subsets
• Species interactions
• Dominant vs. keystone species
• Ecosystem engineers

3
In blue books

• List community characteristics
• Structural diversity (ex trees, understory
  canopy, shrubs, herbaceous layer)
• Diversity (species richness evenness)
• Dominance
• Trophic structure (who eats whom)
• Population size of each species w/in community
• Determination of keystone species
• Levels of interspecific competition
• Functional/guilds group
• F ex nitrogen fixers
• G ex annual wetland species

4
We can classify communities physically or
biologically
5
Community Traits Biodiversity species richness
6
Community Traits Biodiversity -evenness
7
Community Traits Species subsets

• Functional group can be defined either as
• A group of species that function similarly (e.g.,
  have stylet mouthparts)
• A group of species that perform a function in an
  ecosystem (e.g., nitrogen fixers, pollinators,
  etc.

8
Community Traits species interactions
food/interaction webs
9
Ex species interactions
10
Ex trophic facilitation
11
Community Traits Dominant vs. keystone species
12
Ex keystone species and ecosystem engineers
13
Metacommunities
A network of communities linked by dispersal of a
variety of potentially interacting species
14
(No Transcript)
15
(No Transcript)
16
(No Transcript)
17
Metacommunity Theory

• If we understand critical connections between
  communities then we understand how fragmentation
  will affect metacommunity
• Understand impacts on populations within
  communities
• Ultimately, understand ecosystem functioning