1 / 30

Ecosystems

Explore the various ways ecosystems respond to environmental stress, including homeostasis, feedback loops, disturbance, stability, species diversity, and population dynamics.

thanson
Download Presentation

Ecosystems

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Ecosystems Population Responses to Environmental Stress

  2. Ecosystems • Response to Environmental Stress • Homeostasis - the maintenance of favorable internal conditions in a system despite flucutations in external conditions

  3. Ecosystems • Response to Environmental Stress • Feedback Loop - a circuit of sensing, evaluating, and reacting to changes in environmental conditions as a result of information fed back into a system

  4. Ecosystems • Response to Environmental Stress • Feedback Loop • Positive Feedback - a runaway cycle in which a change in a certain direction provides information that causes a system to change further in the same direction

  5. Ecosystems • Response to Environmental Stress • Feedback Loop • Negative Feedback - a cycle in which a change in a certain direction leads to a lessening of that change

  6. Ecosystems • Response to Environmental Stress • Ecosystem Disturbance • Natural Changes • Catastrophic Changes • Drought • Flood • Earthquake • Disease

  7. Ecosystems • Response to Environmental Stress • Ecosystem Disturbance • Natural Changes • Gradual Changes • Climate change • Immigration • Evolution

  8. Ecosystems • Response to Environmental Stress • Ecosystem Disturbance • Human-Caused Changes • Catastrophic • Deforestation • Plowing • Pesticides • Fires

  9. Ecosystems • Response to Environmental Stress • Ecosystem Disturbance • Human-Caused Changes • Gradual • Salinization • Soil compaction • Depletion of groundwater • Tourism

  10. Ecosystems • Response to Environmental Stress • Ecosystem Stability • Inertia • Constancy • Resilience

  11. Ecosystems • Response to Environmental Stress • Ecosystem Stability • Inertia - ability of a living system to resist being disturbed or altered • Constancy - ability of a living system to maintain a certain size • Resilience - ability of a living system to rebound from an external disturbance

  12. Ecosystems • Response to Environmental Stress • Ecosystem Stability • Do ecosystems have to have high inertia and high resilience to be considered “stable”? • Most ecosystems lack high inertia and resilience

  13. Ecosystems • Response to Environmental Stress • Signs of Ecosystem Illness • Drop in NPP • Increased loss of nutrients • Decline in indicator species • Increased populations of pest species • Decline in species diversity • Presence of toxic chemicals

  14. Ecosystems • Response to Environmental Stress • Homeostasis and Time Delays • Time delays between input of a stimulus and the corresponding response • Ozone depletion • Global warming • CO2 scrubbing

  15. Ecosystems • Response to Environmental Stress • Homeostasis and Synergy • Synergistic Reaction - a reaction that occurs when two or more processes interact so that the combined effect is greater than the sum of their separate effects

  16. Ecosystems • Response to Environmental Stress • Homeostasis and Synergy • Synergistic Reactions • Beneficial [CO2 and photosynthesis] • Harmful [ozone depletion + global warming]

  17. Ecosystems • Response to Environmental Stress • Species Diversity and Ecosystem Stability • Ecosystems with higher species diversity have higher NPP and are more resilient • Biodiversity provides “insurance” against catastrophe

  18. Ecosystems • Response to Environmental Stress • Species Diversity and Ecosystem Stability • Ecosystems with higher species diversity have higher NPP and are more resilient • Biodiversity provides “insurance” against catastrophe

  19. Ecosystems • Response to Environmental Stress • Species Diversity and Ecosystem Stability • Tropical Rain Forests • High species diversity • High inertia • Low resilience • Most nutrients stored in vegetation

  20. Ecosystems • Response to Environmental Stress • Species Diversity and Ecosystem Stability • Grasslands • Low species diversity • Low inertia • Burn very easily • High resilience • Most biomass is underground

  21. Ecosystems • Response to Environmental Stress • Population Responses to Stress • Population Dynamics - the major abiotic and biotic factors that tend to increase or decrease the population size and the age and sex composition of a species

  22. Ecosystems • Response to Environmental Stress • Population Responses to Stress • Population Dynamics • Size • Density - number of individuals per area) • Dispersion - spatial distribution of species in their habitat

  23. Ecosystems • Response to Environmental Stress • Population Responses to Stress • Population Dynamics • Biotic Potential - the maximum rate at which a population could grow if it had unlimited resources • Environmental Resistance - all factors that act to limit the growth a population

  24. Ecosystems • Response to Environmental Stress • Population Responses to Stress • Population Dynamics • Carrying Capacity - the number of individuals of a given species that can be sustained indefinitely in a given area

  25. Ecosystems • Response to Environmental Stress • Population Responses to Stress • Population Dynamics • Factors influencing carrying capacity • Interspecific and intraspecific competetion • Immigration • Emigration • Catastrophic events • Food and water supply • Habitat

  26. Ecosystems • Response to Environmental Stress • Population Density and Population Growth • Density-Dependent Population Controls • Increase in significance as population size increases • Competition for resources • Predation • Parasitism

  27. Ecosystems • Response to Environmental Stress • Population Density and Population Growth • Characteristics of dense populations: • Low birth rates • Slow growth rates • High death rates

  28. Ecosystems • Response to Environmental Stress • Population Density and Population Growth • Density-Independent Population Controls • Affect a population’s size regardless of size • Natural disasters • Deforestation • Spraying of pesticides

  29. Ecosystems • Response to Environmental Stress • Population Density and Population Growth • Reproductive Strategies for Survival • r-strategists • K-strategists

  30. Ecosystems • Response to Environmental Stress • Population Density and Population Growth • Survivorship Curves • Show number of survivors of each age group for a particular species • Late Loss • Constant Loss • Early Loss

More Related