Thresholds and State Changes Climate Rate and Trajectory of Successional Changes in Ecosystem Processes Sensitivi ty and Response to Change Frequency and Intensity of Disturbances (Flooding, Fire, Thermokarst, Insect/Pathogens) Sensitivi ty and Response to Change Abundance of Key Species Thresholds and Regime Shifts Hypothesis: Novel boreal landscape patterns emerge when climate change leads to disturbance regimes that alter permafrost integrity and the abundances of key functional types.
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Thresholds and State Changes Climate Rate and Trajectory of Successional Changes in Ecosystem Processes Sensitivity and Response to Change Frequency and.
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Thresholds and State Changes
Climate
Rate and Trajectory of Successional Changes in
Ecosystem Processes
Sensitivity and
Response to Change
Frequency and Intensity of Disturbances
(Flooding, Fire, Thermokarst, Insect/Pathogens)
Sensitivity and
Response to Change
Abundance of Key Species
Thresholds and Regime Shifts
Hypothesis: Novel boreal landscape patterns emerge when climate change leads to disturbance regimes that alter permafrost integrity and the abundances of key functional types.
Thresholds and State Changes
1) How often and under what circumstances does wetland drying or thawing of permafrost cause a change in ecosystem state?
Document hydrologic changes in permafrost-
dominated wetlands
Interaction among landscape position and fire on permafrost thaw, thermokarst development
and wetland drying?
Using Landsat images, develop predictive relationship among
landscape variables and change in wetland extent
T1
Thresholds and State Changes
2) What disturbance-induced changes in functional types might trigger a change in ecosystem state, and what are the ecosystem consequences?
Determine the effects of altered disturbance regime on
successional trajectory and ecosystem processes
Determine the disturbance frequency and conditions under
which new successional trajectories occur
Track tree establishment/community composition post burn. Experimentally
manipulate seed and seedlings
T2a
Document effects of ecosystem change (fire, thermokarst) on
organic matter/nutrient standing stocks and ecosystem processes
Track community composition, C & N stocks/transformations post fire and
thermokarst
T2b
Thresholds and State Changes
2) What disturbance-induced changes in functional types might trigger a change in ecosystem state, and what are the ecosystem consequences?
Document impacts of disease and insect outbreaks on ecosystem processes
Document 1) interannual variation in the abundance of insect and pathogen species, and 2) consequences of
selected outbreaks
Determine impact on microclimate, stand dynamics, NPP, N-fixation
T3
Thresholds and State Changes
Monthly Talks:
May: Spruce budworm and climate change (Juday)
June: Predictive rules for post-fire succession in upland forests (Johnstone, Hollingsworth & Juday)
July: Loss of moss as potential threshold (Turetsky, Mack and Hollingsworth)
August: Permafrost driving variables and responses (Schuur and Jones)
AugustAugust
May/JuneMay/June
The spruce budworm completes its life cycle within a 12-month period, but spread across 2 different years.
First year First year eventsevents
Second year Second year eventsevents
startstart
Temperature controlTemperature controlof spruce budworm of spruce budworm
Han, E.; Bauce, E.; Trempe-Bertrand, F. 2000. Development of the first-instar spruce budworm (Lepidoptera: Tortricidae). Annals of the Entomological Society of America 93(3): 536-540.
gs = green substance gs = green substance
Mean daily temperature, 01 Aug. to 31 Aug., at Fairbanks
“In Alaska, significant budworm damage was detected in 1978 on white spruce in many residential and park areas of Anchorage.” (Holsten: USDA Forest Service, Alaska Region Leaflet R10-TP-11)
Analysis: G. Juday Analysis: G. Juday
Date of spruce budworm heat requirement for peak of adult moth stage at Fairbanks, AK
Data: National Weather ServiceData: National Weather ServiceAnalysis: G. Juday Analysis: G. Juday
Spruce budworm abundance vs. weather at Fairbanks, AK
-1
-0.5
0
0.5
1
1.5
2
2.5
3
1975 1980 1985 1990 1995 2000 2005
year
n A
ug
T -
n d
ate
of
moth
(s
tdev)
0
50
100
150
200
250
inse
cts/
m-2
foli
ag
e
Fairbanks budworm weather index budworm density at BNZ
no budwormsno budworms
DataDatastartstart
“Not known to breed inAlaska.” “Has occurred at Fairbanks, Haines, Pt. Barrow.” Armstrong. 1983. Birds of Alaska.
Cape May Warbler (Dendroica tigrina) :“ … the fortunes of its populations are largely tied to the availability of spruce budworms, its preferred food.”http://www.birds.cornell.edu/AllAboutBirds/BirdGuide/Cape_May_Warbler_dtl.html