Environmental Geography Chapter 5 Part 2

Tundra Biome:

Biomes: focus on Ecotones:

Biomes: Moisture and Temperature Limitations:

Fig. 5.6

Geographical Isolation and Scale: Plant Communities:

Fig. 5.7: Prairie potholes where aquatic communities occupy small, discrete spaces within a larger, grassland biome.

Geographical Isolation and Scale: Plant Communities:

Fig. 5.7: Mixed temperate forest biome where communities and associations overlap and merge together and cover vast areas.

Biogeography:• A branch of geography that

focuses on the geographic distribution of plants and animals over the surface of the Earth.

Biogeography:• Ecological biogeography: Concerned

with how the distribution patterns of plants and animals is affected by the environment (both physical and biological).

• Historical biogeography: Focuses on how the spatial distribution of plants and animals evolve over time and space.

Species Diversity by Latitude:

Table 5.1: Species diversity is generally greatest at lower latitudes.

5.5: Ecosystem Patterns and Distributions:

• Cartographic review of biomes,• Global terrestrial patterns,• Global marine patterns,• Altitudinal zonation, and• Exotic rivers.

Global Distribution of Terrestrial Biomes:

Fig. 5.8: Biomes generally correspond to climate regions.

Human Alteration ofTerrestrial Biomes:

• Temperate forests in China, Europe, and North America,

• Tropical forests in South America, Africa, and Asia, and

• Grasslands throughout all continents (except for Antarctica).

Productivity within the World’s Oceans:

Fig. 5.9: Based on phytoplankton activity, ecological activity is moderate in equatorial latitudes, low in subtropical latitudes, and surprisingly high within the higher latitudes.

Relative Distribution of Marine Productivity:

Fig. 5.10

Global Marine Patterns:• Significant variation related to water

depth and ocean circulation,• Productivity, biomass, and species

diversity are greatest in shallow waters, especially within the coastal (littoral) zone, and

• Irregular coastal zones with deltas, and mixtures of fresh, brackish, and salt water are most productive.

Mixture of Cold and Warm Ocean Currents:

Fig. 5.11

• Mechanisms of Heat Transfer and Intense Biological Productivity

– The Gulf Stream-North Atlantic Drift Ocean Current

• Fig. 5.11

Fig. 5.11: Scanning electron micrograph of marine phytoplankton.

Phytoplankton: Base of Marine Ecosystems:

Global Distribution ofH-type Climates:

Highland Climographs:

Altitudinal Zonation:

Altitudinal Zonation:

Fig. 5.12: Note the effect of elevation, slope, and aspect on terrestrial ecosystems. Temperatures grow cooler with increasing elevation.

Drainage Network: Watershed, Floodplain, and Delta:

Fig. 5.12: Note the geography of headwater, main trunk, and delta.

Exotic Streams within Desert Biomes:

Fig. 5.12: Exotic streams like the Colorado and Nile Rivers result in complex ecosystems.

Running Water in Waterless Regions• Significance of Running Water

– Aeolian processes less significant– Sparse vegetation

• Overland flow erosion• Surface Water in Deserts

– Exotic Streams

– Fig. 5.12

• Nile River (an exotic stream) and Nile Delta:

- Fig. 5.12

5.6: Models of Spatial Dynamics in Ecosystems:

• Succession,• Successional stage,• Climax community,• Disturbance theory,• Environmental management, and• The human factor.

Ecological Succession:• A change in plant and animal

communities.• Describes the way in which biotic

communities succeed one another on the way to a (meta) stable endpoint (the climax).

Ecological Succession:• Primary succession: Succession on a

newly-deposited mineral sediment (e.g. sand dune, beach, volcanic lava and ash deposits, and river deposits).

• Secondary succession: Succession on a previously vegetated area that has been recently disturbed by fire, flood, storm, or human activities.

Ecological Succession:

Evolution:• Change in the genetic makeup of a

population of a species in successive generations.

• If continued long enough, it can lead to the formation of a new species.

• Note that populations - not individuals - evolve.

Natural Selection:• Process by which a particular beneficial

gene (or set of genes) is reproduced in succeeding generations more than other genes.

• The result is a population that contains a greater proportion of organisms better adapted to certain environmental conditions (“survival of the fittest”).

Natural Selection:

Which genetic

adaptations have allowed

this moth species to survive?

Species:• Group of organisms that resemble one

another in appearance, behavior, chemical makeup and processes, and genetic structure.

• Organisms that reproduce sexually are classified as members of the same species only if they can interbreed with one another and produce fertile offspring.

5.7: Land Use as Ecosystems:

• Modern land uses require large amounts of energy and material inputs,

• The resource base (soil and water) is progressively depleted over time, and

• Land use continues to be pushed into marginal environments where risk of disturbance is greater.

Volcanic Eruption and Environmental Disturbance:

Fig. 5.13

Volcanic Eruption and Environmental Disturbance:

Fig. 5.13

5.8: Human Impact and Disturbance of Ecosystems:• Reduction,

• Fragmentation,• Substitution,• Simplification,• Contamination (persistent chemicals

and biomagnification), and• Overgrowth (eutrophication).

Endemic Species:

Fragmentation of Habitats along a Stream:

Fig. 5.14

Human Impact: Contamination:

Fig. 5.15: Increase in DDT via biomagnification within a food chain. Consider DDT as an example of a persistent chemical. DDT, PCB, and dioxin are environmental contaminants that may culminate in synergism.

Human Impact: Overgrowth:

Fig. 5.16: Graph illustrating the concept of cultural eutrophication in an inland lake. Infilling accelerates over time with nutrient loading from development in the watershed around the lake.