Notes

Outline

Introduction to Ecology CERC Certificate Program Columbia University Session 4 – Ecosystem Ecology

Ecosystem Ecology Why is this field important? What is a ecosystem? Trophic Structure Nutrient cycles and food webs Ecosystem Processes Ecosystem engineers Biomes Global Changes

Population Growth Exercise What did you find? Describe the curves – what was happening when? When would you get population oscillations in the Logistic Model? Approximate K for humans?

Forensic Entomology Describe forensic entomology  and degradative succession. Why is this an example of it? What can influence the dating of a murder and how would they? Include at least one from each of the following more general categories: Timing, Location, and Chemically-related factors. How to use forensic entomology for the conservation of animals or of ecosystems?

Succession Definitions Chronological distribution of organisms within an area The sequence of species within a habitat or community through time Shared: Time Single area

Global Distribution of Biodiversity Greatest in areas where NPP is greatest Terrestrial: toward Equator  - Why? Aquatic: near shore, marine upwellings – Why?

Ecosystem Ecology Why is this field important? What is a ecosystem? Trophic Structure Nutrient cycles and food webs Ecosystem Processes Ecosystem engineers Biomes Global Changes

Uses for Ecosystem Ecology Larger Scale phenomena Greater geographic range More factors Ranging from local to global in scope Decreased certainty with increasing scales Focus of international agencies

Ecosystem Ecology Why is this field important? What is a ecosystem? Trophic Structure Nutrient cycles and food webs Ecosystem Processes Ecosystem engineers Global Changes

Definition of an Ecosystem Properties? A system where populations of species group together into communities and interact with each other and the abiotic environment. The entire biological & physical content of a biotope the smallest geographical unit that can be delimited by convenient boundaries

Ecosystem Ecology Why is this field important? What is a ecosystem? Trophic Structure Nutrient cycles and food webs Ecosystem Processes Ecosystem engineers Global Changes

Trophic Structure Definition: Feeding relationships among the species Within a food web/chain Within a single ecosystem

Trophic Structure Influenced by resource availability Both biotic and abiotic More productive areas tend to have greater trophic diversity (as well as species diversity – NPP example) Connectivity Degree and number of associations between species What type of species is likely to have the greatest level of connectivity in the community?

Bottom Up vs. Top Down Control What biotic factor determines organismal abundance at each trophic level?

Trophic Structure Should this be in this lecture? Many would argue not Why not? On what are these folks placing greater emphasis?

Trophic Structure Influenced by resource availability Both biotic and abiotic More productive areas tend to have greater trophic diversity (as well as species diversity – NPP example) Connectivity Degree and number of associations between species What type of species is likely to have the greatest level of connectivity in the community?

Ecosystem Ecology Why is this field important? What is a ecosystem? Trophic Structure Nutrient cycles and food webs Ecosystem Processes Ecosystem engineers Biomes Global Changes

Nutrient Cycles How would nutrient cycles tie in with food webs? Is there anything that is being recycled here?

Stages in Nutrient Cycles Unassimilated Biomass Biomass Biomass Biomass Necromass

Materials Cycled Nutrients Carbon Hydrogen Nitrogen Oxygen Phosphorus Sulfur Energy? Is energy cycled?

Energy Does energy cycle? What defines a cycle? Is energy lost / gained in an ecosystem? How is it lost? How is it gained?

Energy vs. Nutrients Nutrients cycle Conservation of material A lot of new material does not generally enter an ecosystem Energy flows A one-way movement of energy through an ecosystem Energy originates by gathering solar energy Energy lost through growth and metabolism

Ecosystem Ecology Why is this field important? What is a ecosystem? Trophic Structure Nutrient cycles and food webs Ecosystem Processes Ecosystem engineers Biomes Global Changes

Ecosystem Processes Types? Examples: Water purification Decomposition Biomass production Nutrient cycling Carbon sequestration An emergent property at the level of ecosystem

Biodiversity and Ecosystem Processes ­ Biodiversity è ­ ecosystem processes Why so? Trophic redundancy Have multiple species at the same trophic level Performing similar ecological roles Could lose a few species without major changes

Ecosystem Ecology Why is this field important? What is a ecosystem? Trophic Structure Nutrient cycles and food webs Ecosystem Processes Ecosystem engineers Biomes Global Changes

Ecosystem Engineers Species that create novel ecosystems and habitats Examples? Anything that significantly modifies the environment Pigs in Hawaii Peccaries in Brazil Beavers in Northeast Humans everywhere Prominent successional species?

Engineering Questions Can we substitute species as ecosystem engineers? Are cows good bison substitutes? Argument for introducing cattle on Midwest rangeland Are these just keystone species? What do you think?

Ecosystem Ecology Why is this field important? What is a ecosystem? Trophic Structure Nutrient cycles and food webs Ecosystem Processes Ecosystem engineers Biomes Global Changes

Biomes Definition: From Dictionary.com: A major regional or global biotic community Chiefly characterized by the dominant forms of plant life and the prevailing climate Examples: Eastern Deciduous Forest, Arctic Tundra, Grasslands, etc.

Ecological Pyramid Trends down pyramid: Increase in geographic scale From single species to multiple species Increasing number of ecological factors that may  be influential Decreasing certainty in results

Ecosystem Ecology Why is this field important? What is a ecosystem? Trophic Structure Nutrient cycles and food webs Ecosystem Processes Ecosystem engineers Biomes Global Changes

Global Changes What processes are at work at present in the planet? Examples Global Climate Change Acid Rain Spread of Pollution and Toxins Spread of Biotic Pollution How are these occurring? What is the generative force behind them?

Global Change Cause What is the Generative Force behind these changes? US!

Human Impact We have altered nearly all of the Earth that it is profitable for us to do so

Next Week: The Tour of Ecology Concludes Population ecology Community ecology Ecosystem ecology Conservation Issues Next week’s emphasis Is there any hope for the future?