Restoration Ecology, Part 1 Lecture 18 Spring 2014

Transcription

1 What is an Ecosystem? 1 Restoration Ecology, Part 1 Lecture 18 Spring 2014 Ecosystem A dynamic complex of plant, animal and micro-organism communities and their non-living environment interacting as a functional unit What do we get from Ecosystems? 2 What do we get from Ecosystems? 3 Supporting Services 4 Regulating Services 5 Pollination Services = $3.07 billion Pest control = $4.49 billion Dung burial = $0.38 billion The Economic Value of Ecological Services Provided by Insects. John Losey and Mace Vaughn. BioScience April 2006, Vol. 56, No. 4, pgs Phuket, Thailand. New England Aquarium, April Forest and coral reefs in Indonesia Wetlands in Louisiana and Mississippi 1

2 Threats to Ecosystems 6 Will conservation alone solve the problem? 7 Habitat destruction Invasive species Population growth (human) & resource use Pollution Overharvest Climate Change Restoration Ecology the process of assisting the recovery of an ecosystem that has been degraded, damaged, or destroyed Restoration Rehabilitation Ecological knowledge Restoration Ecology 8 Drivers of Change in Ecosystems 9 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? Natural disturbances Disturbance: Any event that changes a community, removes organisms, and/or alters resource availability Varies in intensity and frequency Examples? Natural disturbances 1 Natural disturbances 11 NASA, 2005 Bitterroot fire, John Colgan, Forest Service, 2000 Map of Ice age during Pleistocene era, USGS. Superior National Forest, U.S. Forest Service, 1999 Mt. Saint Helens, Peter Frenzen, 1982 USGS, 2001 Kautz Creek, Mt. Rainier, USGS,

3 12 13 Primary: Gradual establishment of biotic communities in areas with no soil (terrestrial) or bottom sediment (marine). Ceanothus after 1996 wildfire, Dave Powell, USDA, 2004 Succession: A change in species in an area over time following disturbance or creation of a new substrate. Secondary: Succession that begins in an area that already has soil (terrestrial) or bottom sediment (marine) Krakatoa 16 Succession & Disturbance 17 Mt. St. Helens Intermediate disturbance hypothesis Areas with moderate levels of disturbance can foster greater species diversity than areas with low or high disturbance Environmental patchiness Mt. Saint Helens, Jerry Franklin, USDA, 1980 Mt. Saint Helens, Peter Frenzen,

4 Succession & Disturbance Do communities always reach a climax community type over time? Is the pathway of succession predictable? Divides species into habitat islands Relationship between size of island and number of species Edge effects Species number and composition changes Edge effects 22 Why do organisms need to move from one place to another? Wildlife Corridors 232 4

5 Wildlife Corridors Equilibrium & Regulation of Systems 26 Regulation of Systems 27 Equilibrium A condition in which all acting influences are canceled by others, resulting in a stable, balanced or unchanging system Feedback loops Self perpetuating mechanism of change and response to the change Negative Diminishes the effects of a disturbance Positive Amplifies the effects of a disturbance E.g., thermostat regulation of room temperature Positive or Negative Feedback loop? Regulation of Systems Feedback Loop Increased CO 2 = increased plant growth Increased plant growth = increased photosynthesis Increased photosynthesis = decreased CO 2 Positive or Negative Feedback loop? 28 Regulation of Systems Feedback loop Increased temperatures = increased melting Increased melting = less ice/snow cover Less ice/snow cover = less light reflection Less light reflection = more light absorption More light absorption = increased temperature The Ice Albedo Effect Albedo: Measure of reflectivity Positive or Negative Feedback loop? 29 5

6 Feedback Loops: Permafrost & greenhouse gases Permafrost Permanently frozen ground under surface of soil Methane (&CO 2 ) release when melting 30 Equilibrium & Disturbance Non-linear Change A change that is not based on a simple proportional relationship between cause and effect A small change in a driver can produces a disproportionate change in the outcome Tipping Point The levels at which the momentum for change becomes unstoppable 31 Equilibrium & Disturbance 32 Equilibrium & Disturbance 33 Scotch broom Resilience 34 Resilience The level of disturbance that an ecosystem can undergo without crossing a threshold into a different structure or function Yellowstone video and activity What makes an ecosystem resilient? What makes a society resilient? 6