* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Slides
Survey
Document related concepts
Habitat conservation wikipedia , lookup
Occupancy–abundance relationship wikipedia , lookup
Storage effect wikipedia , lookup
Ecological fitting wikipedia , lookup
Biodiversity action plan wikipedia , lookup
Restoration ecology wikipedia , lookup
Fauna of Africa wikipedia , lookup
Reconciliation ecology wikipedia , lookup
Theoretical ecology wikipedia , lookup
Invasive species wikipedia , lookup
Latitudinal gradients in species diversity wikipedia , lookup
Transcript
Restoration Ecology, Part 2 Lecture 19 Spring 2014 1 Restoration Ecology Major questions: • Will an ecosystem return to the same ecosystem after disturbance? – Succession • How is balance maintained in food webs? – bottom up vs. top down models – Competition & predator-mediated co-existence • What are invasive species, how do they affect ecosystems and, should they always be removed? • What makes an ecosystem resilient? • Which is more important to consider; species diversity or functional groups? Biological Diversity Species diversity: variety of species in an area; includes • Species richness – Total number of different species in a community • Species evenness (relative abundance) – The proportion each species represents of the total number of individuals in the community 3 Species Diversity Which community is more diverse? Fig. 54.10 4 5 Biodiversity “Hot Spots” See IG 9.5 Endemic species A species found only one location in the world 6 Genetic Diversity • Do subspecies matter? 7 Restoration Ecology: Diversity & Functional Groups Functional groups • Groups of species that have the same function within an ecosystem Functions? 8 Functional Group: Seed Dispersers • Is functional equivalency sufficient? • Case study: seed dispersal – Frugiverous animals • Transport seeds long distances • Scarification 9 Functional Group: Seed Dispersers Hypotheses: • Plants whose seed dispersers go extinct will also go extinct • “megafaunal-syndrome”: plants with very large fruits and seeds may have evolved to attract the megafauna to consume and (often exclusively) disperse them 10 11 Functional Group: Seed Dispersers • Seed size decline in palms – Loss of large, large-gaped frugiverous birds – Smaller seeds, lower survival Functional Group: Seed Dispersers • Re-caching by rodents – Seed predators 12 13 Functional Group: Seed Dispersers • Replacement of extinct Mauritian tortoises with Aldabran tortoises Functional Group: Seed Dispersers Spurge olive • Seeds dispersed to different habitat Lilford's Wall Lizard Pine marten 14 Symbiotic Relationships Symbiosis – intimate living together of members of two or more species. • Mutualism • Parasitism – pathogen • Commensalism Fig. 54.8 15 Interactions between Species Species A Predation Herbivory Competition Mutualism Parasitism Commensalism + + + + + Species B + 0 16 17 Species Interactions Competition • Attempts by two or more individuals to use the same limited resources in an ecosystem • Interspecific (between different species) • Intraspecific (within same species) • -/- species interaction Avoiding competition Resource partitioning or Niche differentiation • Species evolve more specialized traits that allow them to use shared resources differently 18 Avoiding competition Generalists: Broad ecological niche Examples? Specialists: Narrow ecological niche Examples? 19 20 Predator-Mediated Coexistence • When the presence of a predator allows for the coexistence of two (or more) competing species in a community • Increases species diversity Predator-Mediated Coexistence Observation • Mytilus (mussel) is most abundant species • Many other species present, but in much lower abundance • Pisaster (sea star) feeds on Mytilus Hypothesis • Pisaster is a keystone species that allows for greater species diversity in community 21 Predator-Mediated Coexistence Test • Remove Pisaster from some areas Results • Species richness decreased in areas with no Pisaster Conclusion • Pisaster allows for coexistence of competing species 22 See Fig. 19.14 23 Competition Examples Invasive species 1) non-native (or alien) to the ecosystem under consideration and 2) whose introduction causes or is likely to cause economic or environmental harm or harm to human health. Invasive species & competition Zebra Mussel (Dreissena polymorpha) • Native to Russia • Introduced to U.S. in 1988 by ballast water • Huge number of offspring • Competes for space 24 25 Invasive species & competition North American gray squirrel vs. red squirrel in Britain • N.A. gray squirrel introduced early 19th C • Larger, more aggressive • Can eat newly fallen acorns 26 Restoration Ecology & Invasive Species • Removal of invasive organisms • Restoring native organisms – Or functional equivalents • Ongoing Management 27 Invasive species & competition Saltcedar or Tamarisk (Tamarix spp.) • Introduced to Southwestern U.S. ~ 1850s • Forms monospecific stands • Outcompetes native plants for water 28 Restoration Case Study: Santa Cruz Island • Channel Islands “Galapagos of North America” • Many endemic species • Invasive Species – Sheep & pigs introduced in mid-1800s – Golden Eagle - 1990s 29 Restoration Case Study: Santa Cruz Island • Restoring native organisms – Santa Cruz island fox – Bald Eagle Invasive Species & Biological Control • Biocontrol – Reduction of an invasive species by using its natural enemies – Introduction of a new species • Goal – Reduce rather than eradicate 30 Invasive Species & Biological Control • Criteria – – – – – – Narrow host range Climatic adaptability Synchrony with host (prey) life cycle High reproductive potential Efficient search ability Survival at low host (prey) density 31 32 Invasive Species & Biological Control • Extensive testing • Possible outcomes – No sustainable population – Sustainable population, but limited control – Sustainable population, successful control – Host switch 33 Invasive Species & Biological Control • European rabbits introduced to Australia in 1859 Biocontrol • Myxomatosis virus (1950s) – Resistance rabbits – Evolution of less virulent strains • European rabbit calicivirus disease (RCD) or rabbit haemorrhagic disease (RHD), (1995) Invasive Species & Biological Control • Purple loosestrife (Lythrum salicaria) • Introduced to US in 1800s – Native to Europe & Asia – Ballast water • Impacts – Disrupts hydrological cycle – Displaces native birds and plants • Biocontrol: Leaf beetle (Galerucella calmariensis) 34 35 Restoration Ecology When is an ecosystem considered restored?