1. Human Ecology CHAPTER 23

2. Community: total populations of all species that occupy the same geographic area and interact Ecosystem: community of organisms and the physical environment in which they live Biosphere: all the ecosystems on Earth Ecosystems: Communities Interact with their Environment

3. Where a species lives Habitat: location where species live Geographic range: the area over which an organism is found Limited by: 1.Competition for resources 2.Intolerable conditions 3.Physical obstacles Populations: Dynamics of One Species in an Ecosystem-- [Functional units]

4. Biotic potential: maximum rate of growth of a population Limited by: 1.Number of offspring produced by each member 2.Length of time for individuals to reach reproductive maturity 3.Ratio of males to females 4.Number of reproductive age individuals Exponential growth rate: population doubles repeatedly over similar time periods Population Growth Rate

5. Examples: limitations on nutrients, energy, space, disease, predation, environmental toxins Carrying capacity: resulting balance between biotic potential & environmental resistance Environmental Resistance: Limits Biotic Potential

6. Environmental Resistance Figure 23.3

7. Overlapping niches: foster competition Competitive exclusion: one species out- competes another Succession: leads toward climax community Ecosystems: communities and their physical environment Biomass: total living components of an ecosystem Chemical elements: nonliving components of an ecosystem Communities: Different Species Living Together

8. Producers: autotrophs - photosynthesize Consumers: heterotrophs - eat “others” 1.Herbivores: primary consumers, use green plants as energy source 2.Carnivores: use animals as energy source 3.Omnivores: eat plants & animals as energy sources 4.Decomposers: use dead organisms as energy source Energy Flows through Ecosystems

9. Food web: interactions among producers and consumers Interactions & energy links between producers consumers & decomposers Food Web

10. Water cycle: essential to other biogeochemical cycles Carbon cycle Gaseous cycle: carbon in living organisms is exchanged with atmospheric carbon dioxide Closely tied to photosynthesis and aerobic respiration Chemical Cycles: Recycle Molecules in Ecosystems

11. Nitrogen: essential component of nucleic acids and proteins Nitrogen fixation: process of converting nitrogen gas to ammonium Phosphorus: a sedimentary cycle Chemical Cycles: Recycle Molecules in Ecosystems ( cont.)

12. Pollution Habitat Destruction Overexploitation of Natural Resources Farming Exploitation of scarce forest resources Logging Deforestation Human Impacts: Creating a Biodiversity Crisis

13. Oxygen production from plants Carbon Dioxide release into Atmosphere Clothing, food, medicines Flood Control Biodiversity & Human Health

14. 1.Consume Less 2.Recycle More 3.Lower Worldwide Fertility Rate 4.Reduce Rural World Poverty Toward a Sustainable Future