PALEOCLIMATE RECONSTRUCTION:

Non-Marine Biologic evidence

PALEOCLIMATE RECONSTRUCTION:

Non-Marine Biologic evidence

(plant macrofossils, treelines, pollen, tree rings)(plant macrofossils, treelines, pollen, tree rings)

• These methods typically reveal information for the• These methods typically reveal information for the

• Tree-line: zone of decreasing tree height with increasing latitude (arctic) or altitude (alpine)• Tree-line: zone of decreasing tree height with increasing latitude (arctic) or altitude (alpine)

Artic tree-line: corresponds with the

Artic tree-line: corresponds with the

Evidence of retreating tree lines: Evidence of retreating tree lines:

north or higher than present treeline

found north or higher than present tree-linec. Charcoal layers found north or above present tree line—

north or higher than present treeline

found north or higher than present tree-linec. Charcoal layers found north or above present tree line—

Evidence for advancing tree lines:

• most evidence comes from

Evidence for advancing tree lines:

• most evidence comes from

growth form of treesnear the tree line

is more complex than arctic tree-line due to orographic rainfall and geomorphic processes like landslides

is more complex than arctic tree-line due to orographic rainfall and geomorphic processes like landslides

• Note fluctuation of arctic tree-line during the last 5000 yr:• Note fluctuation of arctic tree-line during the last 5000 yr:

Alpine tree-line:Alpine tree-line:

• studies in Scandanavia and the western USconcur that alpine tree-lines during the middleHolocene (~ 5Ka) were ~150 m higher in elevation than today

• studies in Scandanavia and the western USconcur that alpine tree-lines during the middleHolocene (~ 5Ka) were ~150 m higher in elevation than today

• Evidence from:(genus: Neotoma)—the dens

of these animals contain remarkable collections of the

• Evidence from:(genus: Neotoma)—the dens

of these animals contain remarkable collections of the

• middens in arid climates have been dated back as far as• middens in arid climates have been dated back as far as

• middens indicate that in the SW US 40Ka –12Ka (this corresponds nicelywith high stands during the same period—see previous lecture)

• middens indicate that in the SW US 40Ka –12Ka (this corresponds nicelywith high stands during the same period—see previous lecture)

middensmiddens

: a group of insects restricted to specific climate regimes

: a group of insects restricted to specific climate regimes

• One advantage of insects over pollen is thatinsects respond quickly to climate change; whereas it may take years to change the composition of a forest

• One advantage of insects over pollen is thatinsects respond quickly to climate change; whereas it may take years to change the composition of a forest

This study from a pond in Maine showed that cold water aquatic insects were common during the Younger Dryas

This study from a pond in Maine showed that cold water aquatic insects were common during the Younger Dryas

• millions of tons of pollen are produced each year creating a constant ‘rain’ of pollen, which is

• millions of tons of pollen are produced each year creating a constant ‘rain’ of pollen, which is

• pollen grains are typically 10-150 μm in size and have distinct morphologies• pollen grains are typically 10-150 μm in size and have distinct morphologies

—those that rely on wind for pollination; these produce the most pollen

—those that rely on wind for pollination; these produce the most pollen

• the method works best for lakes at least 1 km2

in area—to pick up the

Examples Of differentTypes of Pollen

Examples Of differentTypes of Pollen

Studies of pollen from lakes in the Eastern USshow that

(today this type of forest is found in Canada and higher elevations of the Appalachians)

was found on high elevations of the Appalachians (today tundra is restricted to Northern Canada)

Studies of pollen from lakes in the Eastern USshow that

(today this type of forest is found in Canada and higher elevations of the Appalachians)

was found on high elevations of the Appalachians (today tundra is restricted to Northern Canada)

From BIOGEOGRAPHY, Lomolino et al. p. 295

From BIOGEOGRAPHY, Lomolino et al. p. 296From BIOGEOGRAPHY, Lomolino et al. p. 296