Plant Ecology - Chapter 20 Paleoecology

The study of historical ecology Changes in global patterns of vegetation, diversity Driven by ecological, evolutionary processes

Paleoecology Plants invaded land during the Paleozoic era, during the later Ordovician and Silurian Major time of evolution, diversification

Paleoecology Diversity of biotic interactions developed early Mycorrhizae, herbivory, animal pollination, animal seed dispersal

Paleoecology Fossil carbon deposits formed from plants during Carboniferous period Coal from remains of wetland plants (ferns, mosses, gymnosperms)

Paleoecology Oil, gas developed from mostly marine plankton (phyto-, zoo-), and maybe wetland plants Dramatic climate change at end of Carboniferous - drier - seed plants began to dominate

Paleoecology Mesozoic era was time of major tectonic plate movement Encompassed Triassic, Jurassic, and Cretaceous periods

Paleoecology Moved from supercontinent Pangaea to breakup into current continents Improved conditions for plant growth, diversification

Paleoecology Ferns, seed ferns, gymnosperms became the dominant flora CO 2 levels 3-4 X higher than today provided warm climate and plentiful CO 2 for photosynthesis

Paleoecology Decline in CO 2 ( mya) changed conditions for plants Cooler, more seasonality Changing climate and continental breakup led to development, diversification of angiosperms

Paleoecology Asteroid impact at end of Mesozoic (65 mya, K-T boundary) Impact debris and/or massive fires led to massive animal and plant extinctions Dinosaurs, and 25-80% of N. Amer, plants (more in south, fewer in north)

Paleoecology Continued decline in CO 2 concentrations (chemical reactions during new mountain weathering) resulted in slow, re-evolution of new species of angiosperms Evolution of C 4 grasses from C 3 ancestors Do better at low CO 2

Paleoecology Recent trends? Global changes in CO 2 ? Change in C 3 and C 4 plant abundance, distribution?

Paleoecology Microfossils - pollen grains Macrofossils - leaves, stems, flowers Used to understand changing plant communities, changing climates

Paleoecology Glacial and interglacial cycling 100,000 years Change in angle, degree of tilt of Earth’s axis

Paleoecology Change in species present in MN from 22,000 ya to present Spruce, ash, birch Pine, elm, oak Grasses Now pines,oaks,sedges

Paleoecology Can track shifts in species distribution through time