1. Individuals and Communities Feb 10, 2012

2. Biogeographic Patterns The initial approaches to explaining biogeographic patterns, developed in the 16 th and 17 th centuries, were based on the Bible. All the plants and animals on Earth were represented on Noah’s Ark Therefore the New World should have the same plants and animals as the Old World Age of Exploration – Captain Cook and Sir Joseph Banks – 1000 new species of plants

3. So many new plants and animals discovered in the 18 th century, how could they have all fit on the ark? Buffon (1756) “The Earth makes the plants; the Earth and the plants make the animals” Buffon’s Law - environmentally similar but isolated regions have distinct assemblages of plants and animals – first principle of biogeography –Exception – cosmopolitan species

4. Buffon’s Law led to… Biomes – Community – Associations –

5. Ecological equivalents – widely separated but physiognomically and structurally similar species and vegetation formations –Von Humbolt Life zones – elevational and latitudinal bands of similar climate and vegetation

6. Superorganism community concept Individualistic community concept

7. Six basic vegetation structural types

8. Figure 6.6

9. Figure 6.1

10. Tropical Rain Forest Found between 25°N and 25°S latitude No distinct dry season, Frost free Equal insolation Major centers of distribution: South and Central America (50%), Africa (20%), and SE Asia and eastern Australia(30%) Occurs in 70 countries Highest biodiversity – 50 to 80% of species on 6 to 7% of Earth’s land surface 300 tree species per hectare, but only 2 individuals per species Structural complexity Seed dispersal

13. Tropical Seasonal Forest Between Tropical Rainforest and 30° latitude Monsoon rainfall pattern Little seasonal temperature change Mainly deciduous canopy Large, fleshy canopy leaves Strata – canopy, shrub, sapling High biodiversity

14. Tropical Seasonal Forest

15. Tropical Savanna Centered around 20° latitude Winter dry season More seasonal temperature variation Grassland with scattered trees and shrubs Trees have thick bark to avoid water loss Seasonal die off of some species Fewer trees because of water availability, large grazing animals, and lightning

16. Many bird species, large grazers, predators Sahel and Serengeti Threatened by desertification, over grazing, poaching, changes in fire regimes

17. Desert Found in areas dominated by subtropical high pressure cells, rainshadows, and continental areas Tropical deserts receive rainfall from the Intertropical Convergence Zone (ITCZ) Cool deserts receive rainfall from winter midlatitude cyclones Biodiversity depends on rainfall Few trees Most vegetation along waterways and roadways

18. Figure 6.13