1. Introduction – Landscape Ecology
Landscape Ecology: Study of landscape structure and processes.
Landscape: Heterogeneous area composed of several ecosystems.
Landscape Elements: Visually distinctive patches in an ecosystem.

2. Vancouver Island marmot (Marmota vancouverensis)
~100 left
Isolated from hoary and
Olympic marmots

3. Vancouver Island marmot (Marmota vancouverensis)
Natural tree succession

4. Vancouver Island marmot (Marmota vancouverensis)
Logging – disjunct patches
- max. dispersal = 7 km
Climate
Prey-Predator Dynamics

5. Human Land Use Practices
Agriculture
Suburban Development
Let’s pick on Indiana:
97% of land in state = privately-owned
In central Indiana,
70+% of land in row crop
<10% in forest
Urban sprawl intensifying

6. Human Impacts
Ecosystem simplification: elimination of species from food webs via human alterations to land
Example: vertebrate communities in ag. landscapes

7. I conducted research in a 3-county area (800 km2) located in west-central Indiana.
Initially, I camped out in Purdue’s GIS lab for 4 months while I developed a GIS data base with 1-m resolution for the study area.
This entailed digitizing all spatial elements from Digital Ortho Quadrangle photos

8. Intensive Agriculture
&
Clean Farming
The matrix was nearly barren during the fallow season with veg cover absent from fields.

9. Timber Extraction
&
Fragmentation

10. Roads: Formation of Barriers in Landscapes

11. Terrestrial “Islands”
Formation of
Terrestrial “Islands”

12. Habitat Fragmentation
Process of breaking contiguous unit into smaller pieces; area & distance components
Leads to:
< remnant patch size
> edge:interior ratios
> patch isolation
< connectivity
Community & Ecosystem processes altered

13. Terrestrial “Islands”
Formation of
Terrestrial “Islands”

15. Habitat Loss vs. Habitat Fragmentation

16. #patches
Patch size
Patch isolation
Edge

18. What about
aquatic systems?

19. What about
aquatic systems?
Con.Bio 12(6)

20. Habitat Fragmentation
area-sensitive species: species that require minimum patch size for daily life requirements
Edge effects: influence of factors from outside of a patch

21. Increased Edge Habitat

22. Increased Edge Habitat

23. Edge Effects Habitat surrounding a patch can:
change abiotic conditions; e.g., temp.
change biotic interactions, e.g., predation
Example of nest predation = edge effect of approximately 50 m into forest patch

24. Habitat Fragmentation
First-Order Effects: fragmentation leads to change in a species’ abundance and/or distribution

25. Habitat Fragmentation
Higher-Order Effects: fragmentation indirectly leads to change in a species abundance and/or distribution via altered species interactions

26. HABITAT FRAGMENTATION
Predators
- Abundance
- Distribution
- Foraging Behaviors +
Ground-Nesting Birds
- Abundance
- Distribution – – –
Avian Competitors Avian Prey
Brood Parasites + +
Parasites
- Abundance
- Distribution
REPRODUCTIVE SUCCESS

27. Habitat Fragmentation: Species-Specific Sensitivity?
Rare species = more vulnerable
Wide ranging species = large-area requirements
Species with reduced mobility = more vulnerable
Species with low fecundity (related to rarity?)
Species with short life cycle (or multi-stage life cycle?)

28. Habitat Fragmentation: Species-Specific Sensitivity?
Ground-nesting birds may be more vulnerable (30-60% reduction in last 25 yrs)
Interior-dependent species
Species vulnerable to human exploitation or disturbance
Specialist species?

29. Habitat Fragmentation: Species-Specific Sensitivity?
Generalizations are a good start
(= hypotheses?), but a little more complex than that……

30. Gehring and Swihart
Biological Conservation
109:

31. Spatial and Temporal
Ecology of Raccoons
Gehring et al. In prep.

32. Swihart et al. 2003. Diversity and Distributions 9:1-8.

33. Brown and Litvaitis. 1995. Canadian Journal of Zoology
73:

34. Implications of Changes in Scale
Insects sampled at 10-m intervals for 100 m

35. Implications of Changes in Scale
Insects sampled at 2000-m intervals for 20,000 m

36. Landscape Processes
Landscape structure influences processes such as the flow of energy, materials, and species between the ecosystem within a landscape.

37. Landscape Structure and Dispersal of Small Mammals

38. Habitat Patch Size and Isolation and Density of Butterfly Populations

39. Organisms and Landscape Structure
African elephants knock down tress.
Change woodland to grassland.
Kangaroo Rats dig burrow systems that modify soil structure and plant distributions.
Beavers cut trees, build dams and flood surrounding landscape.
At one time, beavers modified nearly all temperate stream valleys in Northern Hemisphere.

40. Organisms and Landscape Structure
Johnston and Naiman documented substantial effects of beavers on landscape structure.
Over 63 yrs, area created by beavers increased from 200 ha to 2,661 ha.
Changed boreal forest landscape to complex mosaic.
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41. Organisms and Landscape Structure
Beaver activity between increased quantity of most major ions and nutrients in impounded areas. Three possible explanations:
Impounded areas may trap materials.
Rising waters captured nutrients formally held in vegetation.
Habitats created by beavers may promote nutrient retention by altering biogeochemical processes.
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42. Introduction – Geographical Ecology
MacArthur defined geographical ecology as the search for patterns of plant and animal life that can be put on a map.
Above level of landscape ecology.
Vast breadth
Chapter only focuses on a few aspects.

43. Oceanic Island = Terrestrial Island ?????

44. Island Area and Species Richness
Preston found fewest bird species live on smallest islands and most species on largest islands.
Nilsson et.al. found island area was best single predictor of species richness among woody plants, carabid beetles, and land snails.
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45. Island Area and Species Richness

46. Species-Area Relationship
S = cAz
S = # of species
A = island area
Positive correlation between island size & number of species
Applies to terrestrial “islands” also

48. Habitat Patches on Continents: Mountain Islands
As Pleistocene ended and climate warmed, forest and alpine habitats contracted to the tops of high mountains across American Southwest.
Woodlands, grasslands, and desert scrub, invaded lower elevations.
Once continuous forest converted to series of island-like fragments associated with mountains: Montane.
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49. Lakes as Islands Lakes can be considered as habitat islands.
Differ widely by degree of isolation.
Tonn and Magnuson found the number of species increases with the area of an insular environment.
Barbour and Brown found positive relationship between area and fish species richness.
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50. Lakes as Islands
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51. Marine Islands
MacArthur and Wilson found isolation reduces bird diversity on Pacific Islands.
Williamson summarized data from relationship between island area and species richness in Azore Islands:
Birds show clear influence of isolation on diversity, ferns do not.
Land birds fly across water barriers, and ferns produce large quantities of light spores easily dispersed in the wind.
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52. Marine Islands
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53. Isolation and Habitat Islands on Continents
Lomolino et.al. found a strong negative relationship between isolation and the number of montane mammal species living on mountaintops across the American Southwest.
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54. Equilibrium Model of Island Biogeography
MacArthur and Wilson: Model explaining patterns of species diversity on islands as result of immigration and extinction rates.
Reasoned rates of immigration would be highest on new island with no organisms.
As species began to accumulate, rate of immigration would decline since fewer arrivals would be new species.

56. Equilibrium Model of Island Biogeography
Predicted rate of extinction would rise with increasing number of species on an island for three reasons:
Presence of more species creates a larger pool of potential extinctions.
As number of species increases, population size of each must diminish.
As number of species increases, potential for competitive interactions between species will increase.

57. Equilibrium Model of Island Biogeography
Point where two lines cross predicts the number of species that will occur on an island.
Proposed rates of extinction on islands would be determined mainly by island size.
LG near islands will support highest number.
SM far islands will support lowest number.
SM near and LG far will support intermediate number.
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58. Island Biogeography
equilibrium model suggesting that the number of species occurring on an island represents a balance between immigration (in) and extinction (out)
Robert MacArthur & E.O. Wilson

61. Experimental Island Biogeography
Simberloff and Wilson studied insect recolonization in Florida Keys.
Chose 2 stands of mangroves as control islands, and 6 others as experimental islands.
Defaunated islands
Followed recolonization for 1 yr.
Species number stayed constant, but composition changed considerably.
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62. Experimental Island Biogeography
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63. Colonization of New Islands by Plants
Rydin and Borgegard found variation in spp. richness correlated positively with island area and accounted for 44-85% of variation in species richness among islands.
Small and medium islands continued to accumulate species.
Large islands attained equilibrium of immigration and extinction.
Difficult to separate effects of habitat diversity from area effects.
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64. Manipulating Island Area
Simberloff tested effect of island area on species richness.
In all cases where area was reduced, species richness decreased.
Richness on control island increased slightly.
Islands with reduced area lost species with each reduction in area.
Showed area has positive influence on species richness.
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65. Manipulating Island Area
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66. Island Biogeography Update
Brown and Kodric-Brown found higher immigration rates to near islands can reduce extinction rates.
Lomolino found island area can have a significant effect on immigration rates.
Area and isolation are only two of several environmental factors affect island species richness.
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67. Latitudinal Gradients in Species Richness
Most groups of organisms are more species-rich in the tropics.
Brown grouped hypotheses into six categories:
Time Since Perturbation
More species in the tropics because tropics are older and disturbed less frequently.
More time for speciation, and less frequent disturbance reduces extinction rate.
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68. Latitudinal Gradients in Species Richness
Productivity
High productivity contributes to high species richness.
More energy to divide among population.
Environmental Heterogeneity
More heterogeneity, thus more potential habitat areas and niches.
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69. Latitudinal Gradients in Species Richness
Favorableness
Tropics have more favorable environments.
No extremes to limit diversity.
Niche Breadth and Interspecific Interactions
Various themes
Brown suggests biological processes must play secondary role.
Ultimate causes must by physical differences.
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70. Area and Latitudinal Gradients in Species Richness
Rosenzweig proposed immigration can be largely discounted at broad scales, thus speciation will be primary source of new species.
Species removal via extinction.
Tropics richness is greater due to higher rates of speciation and / or lower rates of extinction.
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71. Continental Area and Species Richness
Rosenzweig found a strong positive relationship between area and species diversity.
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