LARGE-SCALE ECOLOGY UNIT

Chapter 21: Landscape Ecology:  Landscape Structure
Patch Size and Fragmentation of habitat
      Examples: Six landscapes in Ohio – comparison of forested versus deforested habitat
            Important concepts: individual patch size; patch shape; proximity of other patches
                  Ecotones and the edge effect
      Patch Size and the Glanville Fritillary (Melitaea cinxia)  in Finland
            Increasing patch size increases numbers of butterflies on the patch, but the density decreases
                  The decreasing density is NOT a general trend for all species in relation to patch size
Habitat Corridors – connectors between patches; natural or manmade corridors (a management practice
      that is used to connect patches, and effectively make for larger patches)
            Example: the Buckeye Butterfly (Junonia coenia) and Variegated Fritillary (Euptoieta claudia)
                  in South Carolina.  Corridors cut in pine forest connected patches, resulting in higher densities
                  for both butterflies
The discussion of Patches is a perfect lead in to discuss island biogeography in chapter 22

Chapter 22:  Geographic Ecology

Area, Isolation, and Species Richness:  Island Biogeography
            Remember that islands can be land surrounded by water, but also separate lakes in a landscape,                         separate mountaintops in chain, etc.
      Important concepts:  Area (size) of the island, proximity of the island to source areas (for
            immigrants), age of the island, including whether the island was connected in the past to the
            source area or other islands.  The discussion could also include the age of the group of organisms
            from an evolutionary standpoint, which effects how long the group of organisms has had to
            colonize various islands (see Azore Islands data, Fig. 22.6, bottom of pg. 485).
      Examples: Area -- birds on Caribbean Islands, ground beetles (carabids) on islands in a Swedish lake,
            mammals on mountains in the American SW, fish in lakes in northern Wisconsin
      Distance from mainland – bird species richness on islands at various distances from the large island of
            New Guinea; and again mammal species on mountains in the American SW (Fig. 22.7, pg. 486)

The Equilibrium Model – with Immigration/Extinction curves; predictive value for indicating total number
of species an island can have based on area and proximity to source area (Fig. 22.9, pg. 487)

Latitudinal (and Altitudinal) Gradients in Species Richness:
       For overall richness of communities, there is no question that the most diverse terrestrial
communities are tropical rainforests, and coral reefs for aquatic.  There is a general trend of decreasing
species richness as you move away from the equator either toward the south or the north.  This trend is
apparent in specific groups of species as well, such as several plant groups, birds, etc.  But this trend is
NOT true for all species groups.  Examples include salamanders (richer in the temperate zone and highest
in diversity in our own Great Smokey Mountain Nat’l Park), and ichneumonid wasps, also with the highest
diversity in temperate zones.  Can you think of others??