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  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

Relative Values  Most species rich - Consumers  Most biomass - Producers  Most taxonomically diverse - Decomposers –Have fungi, bacteria, protista, and animalia

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

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

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

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

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

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

Question and Hypotheses  How does road intensity affect the decomposer community?  H o : it doesn’t  H a1 : Road intensity decreases diversity of the decomposer community  H a2 : Road intensity improves diversity of the decomposer community

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

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

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

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

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