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Plant Ecology - Chapter 20 Paleoecology 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 CO2 levels 3-4 X higher than today provided warm climate and plentiful CO2 for photosynthesis Paleoecology Decline in CO2 (248-65 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 CO2 concentrations (chemical reactions during new mountain weathering) resulted in slow, re-evolution of new species of angiosperms Evolution of C4 grasses from C3 ancestors Do better at low CO2 Paleoecology Recent trends? Global changes in CO2? Change in C3 and C4 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