Plant Ecology - Chapter 20Paleoecology

PaleoecologyThe study of historical ecologyChanges in global patterns of vegetation, diversityDriven by ecological, evolutionary processes

PaleoecologyPlants invaded land during the Paleozoic era, during the later Ordovician and SilurianMajor time of evolution, diversification

PaleoecologyDiversity of biotic interactions developed earlyMycorrhizae, herbivory, animal pollination, animal seed dispersal

PaleoecologyFossil carbon deposits formed from plants during Carboniferous periodCoal from remains of wetland plants (ferns, mosses, gymnosperms)

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

PaleoecologyMesozoic era was time of major tectonic plate movementEncompassed Triassic, Jurassic, and Cretaceous periods

PaleoecologyMoved from supercontinent Pangaea to breakup into current continentsImproved conditions for plant growth, diversification

PaleoecologyFerns, seed ferns, gymnosperms became the dominant floraCO2 levels 3-4 X higher than today provided warm climate and plentiful CO2 for photosynthesis

PaleoecologyDecline in CO2 (248-65 mya) changed conditions for plantsCooler, more seasonalityChanging climate and continental breakup led to development, diversification of angiosperms

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

PaleoecologyContinued decline in CO2 concentrations (chemical reactions during new mountain weathering) resulted in slow, re-evolution of new species of angiospermsEvolution of C4 grasses from C3 ancestorsDo better at low CO2

PaleoecologyRecent trends?Global changes in CO2?Change in C3 and C4 plant abundance, distribution?

PaleoecologyMicrofossils - pollen grainsMacrofossils - leaves, stems, flowersUsed to understand changing plant communities, changing climates

PaleoecologyGlacial and interglacial cycling100,000 yearsChange in angle, degree of tilt of Earth’s axis

PaleoecologyChange in species present in MN from 22,000 ya to presentSpruce, ash, birchPine, elm, oakGrassesNow pines,oaks,sedges

PaleoecologyCan track shifts in species distribution through time