Download 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
 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?
 Ho: it doesn’t
 Ha1: Road intensity decreases diversity
of the decomposer community
 Ha2: 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