Quaternary Environments Quaternary Ecology

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Quaternary EnvironmentsQuaternary Ecology
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Paleoecological Studies

• Cannot establish experiments and replicate them
• Look for evidence of events that occurred through
  time and use these natural experiments of the
  past to generate hypotheses
• Substitution of Space for Time

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Pollen Analysis

• One of our best records of vegetation assemblages
  
• Allows us to test hypotheses

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Venn Diagrams of Analogue Situations
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Detrended Correspondence Analysis (DCA) of Forest
Communities of Eastern North America
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Taubers Model of Pollen Transport in a Forested
Landscape Where Cg Gravity, Ct Trunk
Space, Cc Canopy, Cr Rain, Cw Flowing
Water
Bradshaws model for the relationship between the
diameter of the pollen catchment and its pollen
source area.
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Scale Issues

• In any ecological or paleoecological study, the
  organism or population is best viewed in a
  context of its life span, life history strategy,
  recurrence interval and magnitude of disturbances

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Spatial and Temporal Domains for a Hierarchical
Characterization of Environmental Forcing Factors
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Environmental Disturbance Regimes, Biotic
Responses, and Vegetation Patterns Viewed in the
Context of Four Space-Time Domains.
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Succession

• Clements View
• Plant community associations that remain intact
• Gleasons View
• Species are distributed individualistically
  according to their tolerances

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Changes in Northern Arizona Vegetation Zones from
Packrat Middens from the Grand Canyon
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Gradient Studies and Elevational Effects During
the Last Glacial Maximum
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Vegetation Change over the last 18,000 years in
the Northern Great Basin
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Changes in Northern and Western Range Limits for
Four Important Eastern North American Tree Taxa
During the Late Quaternary Based on Pollen
Records.
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Maps Depicting Changes in Range Limits Expressed
in Contoured Values of Percent Dominance in
Forests for Oak.
http//www.ngdc.noaa.gov/paleo/pollen/viewer/webvi
ewer.html
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Individualistic Response

• Cold Hardiness
• Response to Disturbances

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Lower Cold Hardiness Thresholds (Killing
Temperatures) Summarized for 25 Woody Angiosperms
from the Eastern Deciduous Forest.
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Cold Hardiness Zone Map.
Region A less than -40 ºC Region B may reach -40
ºC Region C does not reach -40 ºC
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Disturbances

• Fire
• Itasca State Park, Northwestern Minnesota
• Western Margin of the Hemlock-White Pine-Northern
  Hardwood Forest Region
• Changing Fire Frequency 33 or 44 years to 80-90
  years
• Climate
• Controls Vegetation
• Feedbacks to Fire
• Insect Outbreaks

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Changes in Fire Frequency in Northwestern
Minnesota reflected in a Shift from a 44-year
Cycle to an 88-year Cycle (from Clark 1988)
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Distinct Vegetation Types Due to Critical
Climatic Thresholds
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Vegetation Dependence on Climatic Factors
Controlling Final Stable Vegetation State
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Tree Species Decline and Recovery Due to
Pathogens from Pout Pond, New Hampshire
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Pollen Accumulation Rates for Black Ash and
Ironwood/Hornbeam for the Late-Glacial Interval
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Forest Models

• FORET
• JABOWA

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Human Evolution
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North American Land Mammal Ages

Rancholabrean Bison, Mammuthus, Equus, Modern taxa 0 - 0.5 Ma
Irvingtonian Mammuthus, Equus, Euceratherium, Smilodon, Mocrotus 0.5 - 1.8 Ma
Blancan Equus, Nannippus phelgon, Stegomastodon, Borophagus diversidens, Trigonictis, Nekrolagus, Procastoroides, Sigmodon. 1.8 - 4.5 Ma
Hemphillian Machairodus, Agriotherium, Plesiogulo, Osteoborus, Osbornoceros, Prosthennops, Pliohipppus, Astrohippus 4.5 - 8.2 Ma
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Megafaunal Extinction
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Pleistocene Extinctions
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Radiocarbon-Dated Megafauna
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Timing of Megafaunal Extinctions at Different
Locations (from Sturart et al., 2004 )
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Worldwide Megafaunal Extinctions
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Land Bridges During the Last Glacial Maximum
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Human Expansion into the Americas
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Marine Overkill
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