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Native and Invasive Plants Invasive plant • Ability to spread aggressively outside its natural range • Especially in new habitat Invasive plant • Lack insects, diseases and foraging animals Where are they a problem? Disrupted habitats • Thrive on disturbed sites like construction areas and road cuts Why are they a problem? • Threaten native plants and animals • Insects, micro-organisms, birds, etc… • Alter habitats and reduce biodiversity Native Plants Plants growing here for a long time >500 years ◦ Christopher Columbus (1492) 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 Biodiversity The diversity of animals is linked to the diversity of plants ◦ Greater number of plant species means less competition and increased niches Biodiversity 2.5 acres of Amazonian rainforest supports 473 species of trees Only 134 species of trees in Pennsylvania 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 Biodiversity Second trophic level: Herbivores Transfer energy from plants to predators and parasites in higher trophic levels ◦ Mainly insects 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 Keystone Species Keystone species essential role in maintaining diversity ◦ Robert T. Paine research Tidal pool on Pacific Coast ◦ Simple ecosystem Keystone Species Simple Ecosystem ◦ Rivet example Some rivets on airplane more important than others ◦ Seat versus engine 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 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 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 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/ Non-Native (Alien) Aliens colonize areas faster than natives Alien plants interact minimally with ecosystem and pass along very little energy to herbivores (2nd trophic level) Non-Native (Alien) “Pest-free” ornamentals are primarily selected for landscape It takes time for insects to adapt to specific chemical composition of leaves 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 Non-Native (Alien) 90% of herbivorous insects are specialists that have evolved with a plant 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 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 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 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 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 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 Non-Native (Alien) Native applies to local regions Human influence is too rapid for adaption Non-Native (Alien) Birds eat fruit after reproduction Most species depend on insect protein for egg laying and feeding young and nesting 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 http://www.wildflower.org/collections/ 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.scnps.org/ http://arstechnica.com/science/2013/03/by -building-fairy-circles-termites-engineertheir-own-ecosystem/ Fragmentation Biological Dynamics of Forest Fragments Project Island ecosystem stability http://www.stri.si.edu/english/research/faci lities/affiliated_stations/bdffp/