Important slides for PBL

2705 m

Present-Day Plant Elevation Ranges

Data from Hartmann et al., 2002. Rocky Mountain Herbarium

Ziegler Plant Macrofossil Record

90 Taxa, 54 Genera, 36 FamiliesAquatic and wetland plants

Deciduous trees and shrubsConiferous trees

Herbaceous plants

138.5 ka

77.2 ka

MIS 5a

MIS 5b-a

MIS 5c-b

MIS 5c

MIS 5d-c

MIS 5e-d

Late MIS 6-5e

~60 kyr of lake and wetland history

Composite Stratigraphic Section

Elevational Ranges of Modern and Fossil Plant Taxa

Modern and Fossil Taxa

(in veg surveys)

Modern and Fossil Taxa(not in veg. surveys but

likely living nearby)Fossil Only

Extra-local taxaat lower elevations

Within CO Outside CO

Elev

ation

(m)

Montane mixed-conifer forestWarm like the present, or warmer

late MIS 6 to 5c

No trees, cooler than present during MIS 5b

Alpine peatland (fen), conifers only, cooler than present MIS 5a

Conclusions

• Shallow water environments with alkaline and hardwater conditions existed in Ziegler Reservoir throughout the history of the lake, suggesting that groundwater percolating through calcareous bedrock or soil was an important water source.

• MIS 6 - 5c: Macrofossils suggest a mixed montane forest environment was present, similar to today, but including some lower elevation plant taxa (Abies concolor and many herbs) suggesting that the climate was as warm or warmer than today.

• MIS 5d: There is a treeless period, with a climate cooler than today.

• MIS 5a: A peatland (fen) occupied the basin, and conifer taxa Picea sp. and Pinus flexilis were present, deciduous trees were absent, and the climate may have been cooler than today.

• Overall, the climate and vegetation of the Last Interglacial were not largely different from today, even though these two interglacials are separated in time by a glacial period with very different climate and vegetation.