Native and Invasive Plants

1. Native and Invasive Plants

2. Invasive plant • Ability to spread aggressively outside its natural range • Especially in new habitat

3. Invasive plant • Lack insects, diseases and foraging animals

4. Where are they a problem? Disrupted habitats • Thrive on disturbed sites like construction areas and road cuts

5. Why are they a problem? • Threaten native plants and animals • Insects, micro-organisms, birds, etc… • Alter habitats and reduce biodiversity

6. Native Plants Plants growing here for a long time • >500 years • Christopher Columbus (1492)

7. Native Plant Databases • http://www.se-eppc.org/southcarolina/ • http://www.scnps.org/ • http://www.namethatplant.net/ • http://www.wildflower.org/collections/collection.php?start=0&collection=SC&pagecount=10&pagecount=100

8. Biodiversity • The diversity of animals is linked to the diversity of plants • Greater number of plant species means less competition and increased niches

9. Biodiversity • 2.5 acres of Amazonian rainforest supports 473 species of trees • Only 134 species of trees in Pennsylvania

10. 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

11. Biodiversity Second trophic level: Herbivores • Transfer energy from plants to predators and parasites in higher trophic levels • Mainly insects

12. 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

13. Keystone Species • Keystone species essential role in maintaining diversity • Robert T. Paine research • Tidal pool on Pacific Coast • Simple ecosystem

14. Keystone Species Simple Ecosystem • Rivet example • Some rivets on airplane more important than others • Seat versus engine

15. Keystone Species Simple Ecosystem • Removing some species had little effect on populations of remaining species • But removal of a predatory starfish (Pisasterochraceus) caused a collapse of half the remaining species’ population

16. 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

17. 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

18. 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/

19. 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)

20. Non-Native (Alien) • “Pest-free” ornamentals are primarily selected for landscape • It takes time for insects to adapt to specific chemical composition of leaves

21. 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

22. Non-Native (Alien) • 90% of herbivorous insects are specialists that have evolved with a plant

23. 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

24. 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

25. 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

26. 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

27. 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

28. 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

29. Non-Native (Alien) • Native applies to local regions • Human influence is too rapid for adaption

30. Non-Native (Alien) • Birds eat fruit after reproduction • Most species depend on insect protein for egg laying and feeding young and nesting

31. Non-Native (Alien) Non-invasive qualities of alien does not make it native • Clematis vitalbaintroduced 100 years ago • Supports 40 herbivores in homeland but only 1 after 100 years since introduction here

32. http://www.wildflower.org/collections/ • http://www.wildflower.org/collections/collection.php?start=0&collection=SC&pagecount=10&pagecount=100 • http://www.se-eppc.org/ • http://www.dnr.sc.gov/invasiveweeds/illegal1.html • http://www.scnps.org/

33. 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/

34. Fragmentation Biological Dynamics of Forest Fragments Project • Island ecosystem stability • http://www.stri.si.edu/english/research/facilities/affiliated_stations/bdffp/