Wildlife Population Restoration - Session 5 - Lecture Objectives

Question 1

Define ‘Community’

Answer 1

The co-occurrence of individuals of several species over time and space.

Question 2

Define ‘Species Assemblage’

Answer 2

The group of species that are present and potentially interacting within a study area.

Question 3

Define ‘Species Pool’

Answer 3

A species group occurring within a biogeographic region and extends over spatial scales much larger than those of a local species assemblage.

Question 4

What are assemblage rules?

Answer 4

Broad patterns of species co-occurrence.
E.g., species with similar food habits would seldom co-occur

Question 5

What are the three models of community assemblage?

Answer 5

1. Deterministic
2. Stochastic
3. Alternative stable states

Question 6

What are the four parameters you need to know to restore a community successfully?

Answer 6

1. Components of community assemblages
2. Patterns/relationships in community assemblages
3. Rules that govern the expression of the property
4. The mechanisms that caused the patterns

Question 7

What are the three species pools to consider?

Answer 7

1. Regional species pool
2. Local species pool
3. Community (assemblage) species pool

Question 8

Contrast the ‘Community’ approach and the ‘Species Assemblage’ approach

Answer 8

• Community approach looks at individual species
• Species assemblage approach looks at groups of species
• Species assemblage could be part of a larger community
• We focus on identifying the filters and constraints that will modify the species present in a specific area throughout a successional pathway

Question 9

Explain the concept of ecological filters and how they influence your approach to the restoration of communities

Answer 9

• Out of a species pool of potential colonists, only those adapted to the abiotic/biotic conditions will be able to establish successfully
• A continual evolution of ‘survival of the fittest’
• Those organisms not adapted to the habitat are ‘filtering out’ as possible colonists,

Question 10

What are some basic abiotic filters to consider in designing your goals for restoring community assemblages (3)?

Answer 10

1. Climate: rainfall and temperature gradients
2. Substrate: fertility, soil water availability, toxicity
3. Landscape structure: landscape position, previous land use, patch size, and isolation

Question 11

What are some basic biotic filters to consider in designing your goals for restoring community assemblages (8)?

Answer 11

1. Competition
2. Predation-trophic interactions
3. Propagule availability (dispersal)
4. Mutualisms
5. Disturbance
6. Order of species arrival and successional model
7. Current and past composition and structure (biological legacy)

Question 12

Describe the deterministic model of community assemblage

Answer 12

• Community development is determined by abiotic and biotic factors
• Thus, the reassembly of a community after disturbance should be predictable

Question 13

Describe the stochastic model of community assemblage

Answer 13

• Community composition/structure is a random process,
• Recovery depends on the availability of vacant niches and the order of arrival of organisms
• Thus, there is no reason to expect the exact reassembly of the community post-disturbance

Question 14

Describe the alternative stable state model of community assemblage

Answer 14

• Intermediate between other two models
• There are constraints to how communities restructure
• The recovery of a degraded system can follow one of several trajectories, depending on:
• Historical events
• Availability
• Order of arrival of organisms
• An element of randomness inherent in all systems