Quaternary Environments Quaternary Ecology

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

Pollen Analysis  One of our best records of vegetation assemblages  Allows us to test hypotheses

Venn Diagrams of Analogue Situations

Detrended Correspondence Analysis (DCA) of Forest Communities of Eastern North America

Tauber’s Model of Pollen Transport in a Forested Landscape Where: Cg – Gravity, Ct – Trunk Space, Cc – Canopy, Cr – Rain, Cw – Flowing Water Bradshaw’s model for the relationship between the diameter of the pollen catchment and its pollen source area.

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

Spatial and Temporal Domains for a Hierarchical Characterization of Environmental Forcing Factors

Environmental Disturbance Regimes, Biotic Responses, and Vegetation Patterns Viewed in the Context of Four Space-Time Domains.

Succession  Clements’ View  Plant community associations that remain intact  Gleason’s View  Species are distributed individualistically according to their tolerances

Changes in Northern Arizona Vegetation Zones from Packrat Middens from the Grand Canyon

Gradient Studies and Elevational Effects During the Last Glacial Maximum

Vegetation Change over the last 18,000 years in the Northern Great Basin

Changes in Northern and Western Range Limits for Four Important Eastern North American Tree Taxa During the Late Quaternary Based on Pollen Records.

Maps Depicting Changes in Range Limits Expressed in Contoured Values of Percent Dominance in Forests for Oak.

Individualistic Response  Cold Hardiness  Response to Disturbances

Lower Cold Hardiness Thresholds (Killing Temperatures) Summarized for 25 Woody Angiosperms from the Eastern Deciduous Forest.

Cold Hardiness Zone Map. Region A less than -40 ºC Region B may reach -40 ºC Region C does not reach -40 ºC

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 years  Climate  Controls Vegetation  Feedbacks to Fire  Insect Outbreaks

Changes in Fire Frequency in Northwestern Minnesota reflected in a Shift from a 44-year Cycle to an 88-year Cycle (from Clark 1988)

Distinct Vegetation Types Due to Critical Climatic Thresholds

Vegetation Dependence on Climatic Factors Controlling Final Stable Vegetation State

Tree Species Decline and Recovery Due to Pathogens from Pout Pond, New Hampshire

Pollen Accumulation Rates for Black Ash and Ironwood/Hornbeam for the Late-Glacial Interval

Forest Models FORET FORET JABOWA JABOWA

Human Evolution

North American Land Mammal Ages RancholabreanBison, Mammuthus, Equus, Modern taxa Ma Irvingtonian Mammuthus, Equus, Euceratherium, Smilodon, Mocrotus Ma Blancan Equus, Nannippus phelgon, Stegomastodon, Borophagus diversidens, Trigonictis, Nekrolagus, Procastoroides, Sigmodon Ma Hemphillian Machairodus, Agriotherium, Plesiogulo, Osteoborus, Osbornoceros, Prosthennops, Pliohipppus, Astrohippus Ma

Megafaunal Extinction

Pleistocene Extinctions

Radiocarbon-Dated Megafauna

Timing of Megafaunal Extinctions at Different Locations (from Sturart et al., 2004 )

Worldwide Megafaunal Extinctions

Land Bridges During the Last Glacial Maximum

Human Expansion into the Americas

Marine Overkill