Life in a Global Context (Part 3)

8/2/2019 Life in a Global Context (Part 3)

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Life in a Global Context (Part 3)

What ecological factors place limits on a species geographic range?

Abiotic (physical) Dispersal Biotic Biological interactions Habitat selection

What are abiotic factors?

Climate (temperature, moisture) Soils (minerals, texture, acidity) Geology (rock type, land formations) Light (sun, shade) Nutrients (nitrogen, phosphorus, potassium) Habitat Pollutants

Rain Shadow


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Wallaces Line

A hypothetical line demarcating the distribution of Asian andAustralian fauna, passing between the islands of Bali and Lombok to

the south and Borneo and Sulawesi to the north, used especially in

biogeographic studies of evolution.


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Species Gradient


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Biotas of major biogeographic regions vary strikingly


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How will abiotic factors influence distributions?

Restrict access to resourceso Food/nutrientso Habitat

Limit physical toleranceso Hot/coldo Chemistry (toxins)

Physical barrierso River, mountain, lake, and ocean

How would you determine which abiotic factor is limiting the distribution of an

organism?

Field observation of actual range of distribution Determine ecological tolerances


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Correlation between environmental gradients and a speciesoptimum range

Experiments (field transplant, controlled environment)

Transplant Experiment

Control: transplant within range Treatment: transplant outside range

Transplant: Limit of Tree Line

Timberline decreases 100m for every degree in latitude Wardle transplanted seedlings (all died) Transplanted with shade cloth (survived 180m above tree line) Conclusion: temperature and drought interact to control tree line

Limits to Tree Line

Smith and Germino (2002), physiological ecologists transplantedEngelmann spruce (Picea engelmannii) seedlings above tree line inWyoming

o Treatment: Underneath herbaceous canopy (shaded,

competition for water)

On bare soil (high light, no competition for water)


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On bare soil, surrounded by herbaceous canopy(high light, competition for water)

Approaches to Studying Ecology

Observational approacho Detecting patterns in natureo Quantitative monitoring (LTR/chronology studies)o Correlation Causation

Experimental approacho Design (treatments, controls, replication)o Process know linked to patternso Develop confidence in predictions

Theoretical approacho Theory is based on modelso Statistical model, conceptual model, or simulation modelso

Experimental Approach


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Realism Precision & Control

Global Warming Trends

Keelings Curve

Natural Experiment

Volcano

Large scale

Low cost

Difficult to replicate

Lab Experiment

Greenhouse

Small scale

Medium to low cost

Low variation in

replicates

Field Experiment

Natural forest

Large-small scale

High cost

High variation in replicates

Semi-Field Experiment

Plantation

Small scale

Medium to low cost

Medium to low variation in replicates


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Will global warming impact species distributions and limits?

Alpine tree lines increase 1000m with a 3C/year increase intemperature

Arctic tree line expansion Species replacement (deciduous vs. boreal) Grassland succession into warm dry forest (Douglas fir/Jack Pine) Ecological processes (fire cycles, flooding regimes, landslides) Wetland shrinkage Habitat changes faster than organism dispersal or adaptation

Tropical Cloud Forest

Cloud layer at 1000-3000m above sea level Unique vegetation and animals More epiphytes, pteridophytes, and bryophytes than low valley rain

forest

Temperature drops 6C/1000m

Will global warming influence this ecosystem?

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Life in a Global Context (Part 3)