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Native and Invasive Plants
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Invasive plant Ability to spread aggressively outside its natural range Especially in new habitat
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Invasive plant Lack insects, diseases and foraging animals
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Where are they a problem? Disrupted habitats Thrive on disturbed sites like construction areas and road cuts
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Why are they a problem? Threaten native plants and animals Insects, micro-organisms, birds, etc… Alter habitats and reduce biodiversity
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Native Plants Plants growing here for a long time >500 years ◦ Christopher Columbus (1492)
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Native Plant Databases http://www.se-eppc.org/southcarolina/ http://www.scnps.org/ http://www.namethatplant.net/ http://www.wildflower.org/collections/coll ection.php?start=0&collection=SC&pagec ount=10&pagecount=100 http://www.wildflower.org/collections/coll ection.php?start=0&collection=SC&pagec ount=10&pagecount=100
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Biodiversity The diversity of animals is linked to the diversity of plants ◦ Greater number of plant species means less competition and increased niches
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Biodiversity 2.5 acres of Amazonian rainforest supports 473 species of trees Only 134 species of trees in Pennsylvania
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Biodiversity Trophic level is the position an organism occupies in food chain. First trophic level: Plants Plants capture sun’s energy and turn it into food for the rest of us
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Biodiversity Second trophic level: Herbivores Transfer energy from plants to predators and parasites in higher trophic levels ◦ Mainly insects
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Biodiversity Worldwide, 37% of animal species are herbivorous insects Pound for pound, insects contain more protein than beef 96% of birds rely on insects and spiders to feed young
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Keystone Species Keystone species essential role in maintaining diversity ◦ Robert T. Paine research Tidal pool on Pacific Coast ◦ Simple ecosystem
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Keystone Species Simple Ecosystem ◦ Rivet example Some rivets on airplane more important than others ◦ Seat versus engine
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Keystone Species Simple Ecosystem Removing some species had little effect on populations of remaining species But removal of a predatory starfish (Pisaster ochraceus) caused a collapse of half the remaining species’ population
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Keystone Species Complex System No central players ◦ Jenga example How vital a block’s role to the tower’s stability is based on the presence of other blocks
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Keystone Species Complex System Every time block is removed, role and importance of other blocks changes Almost any species can be a keystone species depending on circumstances
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Trophic Cascades The impact on other species when removing a keystone species ◦ Predator example Yellowstone wolf population reduced Moose spend less time looking around ◦ More time grazing Overgrazing led to erosion, impacting streams, fish, plants, etc. http://www.twp.org/
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Trophic Cascades Yellowstone Wolves https://www.youtube.com/watch?v=ysa5O BhXz-Q https://www.youtube.com/watch?v=ysa5O BhXz-Q https://www.youtube.com/watch?v=GeF2 5GJleA8 https://www.youtube.com/watch?v=GeF2 5GJleA8
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Non-Native (Alien) Aliens colonize areas faster than natives Alien plants minimally interact ◦ Pass along very little energy Plants 1 st trophic level Herbivores (Insects) 2 nd trophic level
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Non-Native (Alien) “Pest-free” ornamentals are primarily selected for landscape It takes time for insects to adapt to specific chemical composition of leaves
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Non-Native (Alien) Paperbark tea tree introduced to Everglades in 1900 Presently, 8 species of arthropods feed on leaves, opposed to 409 back in Australia
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Non-Native (Alien) 90% of herbivorous insects are specialists that have evolved with a specific plant
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Non-Native (Alien) Insects develop ability to overcome physical and chemical defenses of host, but limited to feed on that host only ◦ Mainly due to leaf chemistry Insects develop enzymes that detoxify chemistry
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Non-Native (Alien) Tannins in oak leaves would bind protein if we eat them, starving us Lima beans contain cyanide unless boiled Cucumber leaves are lethal
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Seeds from a plant commonly called wild potato, known to botanists as Hedysarum alpinum. According to my hypothesis, a toxic alkaloid in the seeds weakened McCandless
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Seeds from a plant commonly called wild potato, known to botanists as Hedysarum alpinum [caused slow-developing severe weakness that brought about starvation].
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Non-Native (Alien) 10% of insect herbivores are generalists that eat several types of plants Ability to produce very powerful gut enzymes called mixed-function oxidases Feed on many alien plants, but not enough
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Non-Native (Alien) Compare diversity and biomass of insects on 4 woody natives versus 5 aliens Native plants produce 4x more biomass Supported 3.2x more species
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Non-Native (Alien) Compare diversity and biomass of insects on 4 woody natives versus 5 aliens In terms of caterpillars (most important to birds), 35x more than alien plants Natives produced 2x as many generalists
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Non-Native (Alien) A plant can become native regardless of origins Norway maple introduced from Europe in 1756 Still has few insect feeders Compare to 80 millions years of coevolution, 250 years isn’t much
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Non-Native (Alien) Native applies to local regions Human influence is too rapid for adaption
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Non-Native (Alien) Birds eat fruit after reproduction Most species depend on insect protein for egg laying and feeding young and nesting
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Non-Native (Alien) Non-invasive qualities of alien does not make it native Clematis vitalba introduced 100 years ago Supports 40 herbivores in homeland but only 1 after 100 years since introduction here
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http://www.wildflower.org/collections/ http://www.wildflower.org/collections/coll ection.php?start=0&collection=SC&pagec ount=10&pagecount=100 http://www.wildflower.org/collections/coll ection.php?start=0&collection=SC&pagec ount=10&pagecount=100 http://www.se-eppc.org/ http://www.dnr.sc.gov/invasiveweeds/illega l1.html http://www.dnr.sc.gov/invasiveweeds/illega l1.html http://www.scnps.org/
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http://arstechnica.com/science/2013/03/by -building-fairy-circles-termites-engineer- their-own-ecosystem/ http://arstechnica.com/science/2013/03/by -building-fairy-circles-termites-engineer- their-own-ecosystem/
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Fragmentation Biological Dynamics of Forest Fragments Project Island ecosystem stability http://www.stri.si.edu/english/research/faci lities/affiliated_stations/bdffp/ http://www.stri.si.edu/english/research/faci lities/affiliated_stations/bdffp/
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