1 introduction: what is ecology ? chapter 1. 2 outline overview of ecology ecology of forest birds...

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Introduction: What Is Ecology ?

Chapter 1

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Outline

• Overview of Ecology• Ecology of Forest Birds• Ecology of Bumblebees• Forest Nutrient Budgets• Vegetation Change: Pollen Records• Nature and Scope of Ecology

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Overview of Ecology

• Ecology: Study of relationships between organisms and the environment. Simple definition does not convey the

extreme breadth of this discipline.• Ecosystem: Includes all organisms living in

an area, and the physical environment with which these organisms interact. Biosphere: Highest level of ecological

organization.

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Ecology of Forest Birds

• MacArthur studied ecology of five species of warblers in spruce forests in N.A. Theory predicted two species with

identical ecological requirements could not coexist indefinitely.

Studies found warblers coexisted by feeding in different zones of the same tree.

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Warbler Feeding Zones

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Ecology of Bumblebees

• Bumblebees live in many cool regions. Heinrich estimated energy budget of

individuals foraging on different flowers and under different temperatures.

Energy Gain / Loss Energy Intake - Energy Expenditure.

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Ecology of Bumblebees

• Field and Laboratory Results Amount of energy expended during flight

was independent of air temperature. Bees elevated temperature of thorax to

stay warm in cool climates.

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Ecology of Bumblebees

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Forest Nutrient Budgets

• Due to heavy rainfall, many rainforest soils are nutrient-poor. Nutrient stores in rainforest canopies are

associated with epiphytes. Epiphyte mats contain significant

quantities of nutrients. Trees send roots up to epiphyte mats

to access nutrients.

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Forest Nutrient Budgets

• Likens and Bormann estimated 90% of nutrients in a New Hampshire forest were locked up in soil organic matter. Approximately 9.5 % was tied up in

vegetation. Streamflow output amounted to < 1%.

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Vegetation Change: Pollen Records

• Many environmental changes occur over large spatial or temporal scales.

• Davis monitored plant pollen deposited in lake sediments in the Appalachian Mtns. Documented large temporal changes to

nearby plant communities.

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Vegetation Change: Pollen Records

• Milne modeled transitions between ecosystems (ecotones) as phase transitions. Searched for edges between critical

densities of vegetation along ecotones. Suggested areas of gradual change

within a landscape are most likely to contain biological responses to environmental changes.

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Vegetation History from Pollen Sediments

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Nature and Scope of Ecology

• Ecology: Study of relationships between organisms and the environment. Wide variety of approaches.

Large temporal and spatial scales. Field Lab Observational Manipulative

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Review

• Overview of Ecology• Ecology of Forest Birds• Ecology of Bumblebees• Forest Nutrient Budgets• Vegetation Change: Pollen Records• Nature and Scope of Ecology

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