Lecture 7: Habitat Fragmentation, Degradation, and Landscape Change

Question 1

Habitat Fragmentation

Answer 1

the breaking apart of continuous habitat into distinct pieces.

Question 2

Case Study: (MacArthur -Wilson - Simberloff) Island Biogeography

Answer 2

experimental defaunation
1. Take initial census of all terrestrial arthropods on 4 islands.
2. Use insecticide to kill of arthropod species
3. Take census every month to monitor recolonization.
Result: large island + close to mainland = many species
small island + far from mainland = few species

Question 3

Patterns of Island Biodiversity

Answer 3

• large islands support more species than small
• island close to mainland support more species
• Archipelago Islands support more species than lone

Question 4

Minimum Viable Population (MVP)

Answer 4

the minimum population size needed to:

• retain 90% of genetic diversity of the species for 200 yrs
• have 95% confidence of species survival for 100 yrs

Question 5

Minimum Viable Area (MVA)

Answer 5

• the area needed to sustain an MVP
• increases with increasing body size of species (larger animals need more food, more area, etc.)
• depends on species tropic levels and requirements

Question 6

Consequences of Fragmentation

Answer 6

• increased edge effects
• microclimate changes
• division of populations
• increased potential for disease
• restricted access to food and mates
• changes to interspecies interactions
• limits to dispersal/colonization

Question 7

Edge Effects

Answer 7

ecological effects resulting from proximity to the edge of a habitat or transition between habitats.
Including:
-Abiotic Changes: increased isolation, temperature, wind, drying, etc.
-Biotic Changes: change in species composition, abundance, behavior, interactions, etc.

Question 8

Edge Species

Answer 8

species associated with high densities in edge or transition habitats.
-ex: deer, raccoons, domestic cats, cowbirds

Question 9

Landscape Change

Answer 9

the combined effects to fragmentation, degradation, and land use conversion on a broad scale.

Question 10

Landscape Ecology

Answer 10

interdisciplinary science of studying and improving ecological processes and relationships at the landscape scale.

Question 11

4 Stages of Landscape Change

Answer 11

1. Intact Landscape - most original vegetation remains with little or no modification
2. Variegated Landscape - Dominated by the original vegetation, but with modification
3. Fragmented Landscape - Original Vegetation fragments are a minor component in landscape dominated by other land uses.
4. Relict Landscape - <10% of original vegetation remains, with highly modified surroundings.