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Decomposers: The end and the beginning

Decomposers: The end and the beginning. James Danoff-Burg SEE-U Columbia University. Food Sources of the Players in our Ecological Drama. Producers - get energy from sun Consumers - get energy from living tissue Decomposers - get energy from dead tissue. Roles of Decomposers.

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Decomposers: The end and the beginning

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  1. Decomposers: The end and the beginning James Danoff-Burg SEE-U Columbia University

  2. Food Sources of the Players in our Ecological Drama • Producers - get energy from sun • Consumers - get energy from living tissue • Decomposers - get energy from dead tissue

  3. Roles of Decomposers • Break down tissue of dead organisms • Convert it into novel tissue • Called Secondary Production • Make available nutrients for plants • Thus, they begin the energy cycling process again by recycling energy back into the community

  4. Relative Values • Most species rich - Consumers • Most biomass - Producers • Most taxonomically diverse - Decomposers • Have fungi, bacteria, protista, and animalia

  5. Decomposers at a Carcass • Vertebrates (macrofauna) • Large invertebrates (mesofauna) • Smaller invertebrates (microfauna) • Fungi (microfauna) • Protists (present throughout) • Bacteria (present throughout)

  6. Forensic Entomology • Applied succession theory • Used to solve crimes • Date the time of death or deposition of a body • Great accuracy initially, less accurate with increasing time • Primarily study beetle and flies

  7. Decomposers at a Log • Bacteria, Protists, and Fungi • Smaller invertebrates (ants and termites) • Larger invertebrates (roaches, beetles, etc.) • Small mammals

  8. Succession Involving Decomposers • Degradative • single large resource (log, carcass) • resource is exhausted at the end • regular progression of species through that resource • unidirectional process of succession • this is the case for all successional processes

  9. Population Control • Producers • Bottom-up control (sunlight and resource availability) • Consumers • Either bottom-up (resources) or top-down (from predation, etc.) • Decomposers • Bottom-up • Explosive population growth with resource availability

  10. Today’s Activity at the BRF • How does road intensity affect the decomposer community? • Roads detrimentally affect the populations of many species • Impact of road changes with group of organisms • Some plants and insects only respond a few meters in • Larger vertebrates (birds) avoid to 200 m

  11. Question and Hypotheses • How does road intensity affect the decomposer community? • Ho: it doesn’t • Ha1: Road intensity decreases diversity of the decomposer community • Ha2: Road intensity improves diversity of the decomposer community

  12. Study Organisms • Necrophagous beetles • ecological category for anything feeding on carrion • Carrion beetles (Silphidae) • Rove beetles (Staphylinidae) • Scarab beetles (Scarabaeidae) • Leiodid beetles (Leiodidae)

  13. Experimental Layout • Three road types (5 of each road) • single lane dirt road • closed canopy • low to no traffic intensity • two lane paved road • relatively open canopy • moderate traffic intensity • four lane paved road • open canopy • high traffic intensity

  14. Sampling Method • Hanging baited traps • 2-liter bottles • two flap openings • baited with a single chicken thigh per trap • left out for 5 days (set out on Sunday) • Count richness and abundance of beetles in lab • only beetles- no flies • flies can fairly easily escape the trap

  15. Data Collection • Go to field • Collect traps • Count, ID larger beetles, & release • Preserve smaller ones with alcohol • Count under microscope • Sort to morphospecies

  16. Analyses & Presentation • Count, chart, chi-square tests • Write up a PowerPoint presentation of entire project • Each person makes up two slides • Finish everything by 4:30 pm

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