Forests and Changing Climate “Mitigation deals mostly with carbon, adaptation deals with water” John Hoklren, OSTP “Of all the outputs of forests, water may be the most important” National Academy of Sciences 2008
Feb 23, 2016
Forests and Changing Climate
“Mitigation deals mostly with carbon,adaptation deals with water”
John Hoklren, OSTP
“Of all the outputs of forests, water may be the most important”
National Academy of Sciences 2008
Expected Climate Change Effects
Precipitation: more rain & less snow 33% snowpack loss 1.6 °C increase by 2060 (Knowles 2002)
Earlier snowmelt Faster snowmelt
Predicted Loss of Snowpack(Knowles 2002)
°C Increase % Snowpack Loss
Year
0.6 5 2030
1.6 33 2060
2.1 50(43 to 66)*
2090
*Effect greater in northern Sierra and Cascades
3 °C increase by 2070-2099 (Bureau of Reclamation 2011)
Modeled Mean Annual Flow& Percent Decrease (Null et al. 2010)
Watershed Basecase Percent decrease from Basecase
2° C increase 6° C increase
Feather 5776 2.2 8.8Yuba 3020 2.0 7.1Bear 492 3.6 9.6American 3556 3.1 9.5Cosumnes 603 5.2 14.0Mokelumne 979 3.4 9.4Calaveras 330 3.3 8.9Stanislaus 1561 2.4 8.1Tuolumne 2445 1.8 5.8Merced 1348 3.0 8.2San Joaquin 2294 1.3 4.1Kings 2117 1.1 3.6Kaweah 586 3.8 11.5Tule 199 4.6 14.3Kern 926 4.2 12.2
AnimalsVegetation
Soil Water
Bacteria &
Fungus
Nutrients & Carbon
Pacific Southwest Research Station, Fresno, CA
Kings River Experimental WatershedsKREW
KREW Study: Paired Watershed Experiment
Annual Stream Discharge
Climate Change
& Water Yield
Bull 203Size: 342 acresElevation: 7170-8170
ftMean Temp: 6.9°C
Providence 303Size: 327 acresElevation: 5670-6530
ftMean Temp: 8.8°C
Water Cycle or Budget
Atmosphere Transpirationby Vegetation
Soil Streams& Lakes
Evaporation
Oceans
Percent of Precipitation to Become Runoff
0
10
20
30
40
50
60
70
WY 2004 WY 2005 WY 2006
% o
f Pre
cip
Providence
Bull
Findings: Water Yield & Climate
Precipitation amount (30-80 in/year) Reaches maximum at 3,940 ft
Runoff ratio (discharge / precipitation) 10% increase per 1,000 ft
Snow-dominated 2 to 3 times discharge
Trees at rain-snow using more water in winter (evapotranspirtation 30 in)
Upper Kings River BasinGoulden et al. 2012
Measured evapotranspiration 10,000 ft 18 in/yr 6,600 ft 30 in/yr (60% higher)
Due to winter dormancy at cold, snow dominated
Both are mixed-conifer forest
Atmospheric lapse is -5.3 °C per 3,300 ft 3 °C warming shift vegetation upslope ET increase of up to 60%
Climate Change& Water Quality
Erosion: Roads & Wildfire Increased sediment yield because
Climate change = vegetation disturbance
Road maintenance and decommissioning effective but will not mitigate increase in sediment from increased wildfire
Goode et al. (2012) Idaho case study
Findings: Flow Pathways Determined using water chemistry
Primary: Subsurface flow ~ 60% Soil-bedrock interface
Snowmelt runoff < 40% Fall storm runoff < 7%
Adaptation: Multiple Stressors
Air pollution Increased wildfire Insect outbreaks Climate change
“I would feel more optimistic about a bright future for man if he spent less time proving that he can outwit Nature and more time tasting her sweetness and respecting her seniority.”
E.B. White