Transcript How wildfire affected aquatic invertebrates in Yellowstone National

Cody Bish and Lusha Tronstad
Wyoming Natural Diversity Database
 CO2 concentrations are increasing
 Increased CO2 predicted to cause climate change
 Wildfire severity and frequency are predicted to
increase with global climate change
Fire
 1.4 million acres burned in the 1988 wildfire
 1/3 of streams in the park were affected
 Watersheds of 4 largest lakes in Yellowstone were
burned
 Several wildfires have burned in Yellowstone since
1988 fire
 Wildfires impact
watersheds
 Eliminates forest cover
and vegetation
 Influences hydrology
 Changes nutrient cycling
 Alters biological life
 How were aquatic invertebrates affected by wildfire?
 The East wildfire burned in August through
September 2003
 East side of Yellowstone Lake
 Crown fire
 Started by
lightning
 Samples were collected in Cub Creek
 95% of watershed burned in East fire
 Collected samples summers of 2003 (pre-fire) and 2004 & 2005 (post-
fire)
 Collected aquatic invertebrates with a Hess sampler every 2-4 weeks
 Samples were then sorted, counted, measured, and identified under a
dissecting microscope
 Calculated density and biomass
50000
45000
2003
40000
2004
35000
Density (ind/m 2 )
2005
30000
25000
20000
15000
10000
5000
0
27-Apr
17-May
6-Jun
26-Jun
16-Jul
5-Aug
25-Aug
14-Sep
2004 flood reduced invertebrate densities
4-Oct
24-Oct
13-Nov
60000
2003
50000
2004
2005
Density (ind/m2 )
40000
30000
20000
10000
0
Plecoptera
Diptera
Coleoptera
Diptera decreased after fire
Ephemeroptera
Trichoptera
18000
16000
14000
Density (ind/m 2 )
12000
10000
2003
2004
8000
2005
6000
4000
2000
0
Filterer
Gatherer
Generalist
Predator
Scraper
The response of functional feeding groups after fire varied
Shredder
Biomass (mg/m 2 )
4500
4000
2003
3500
2004
3000
2005
2500
2000
1500
1000
500
0
17-Apr
6-Jun
26-Jul
14-Sep
Individual body size increased in 2005 compared to 2003
3-Nov
800
700
2003
600
Biomass (mg/m 2 )
2004
500
2005
400
300
200
100
0
Plecoptera
Diptera
Coleoptera
Ephemeroptera
Tricoptera
In general invertebrate biomass increased two years post fire
Biomass (mg/m 2 )
1000
900
2003
800
2004
700
2005
600
500
400
300
200
100
0
Gatherer
Generalist
Predator
Scraper
Functional feeding groups increased biomass post fire
Shredder
 Wildfire can both positively and negatively affect
invertebrates
 First year post-fire densities and biomass decrease due
to floods
 Two years post-fire densities and biomass increase
2004
Bottom-up effect
Aquatic
Invertebrates
2005
Bottom-up
effect
Aquatic
Invertebrates
Hydrology
Hydrology