Forests and Changing Climate “Mitigation deals mostly with carbon, “Mitigation deals mostly with carbon, adaptation deals with water” John Hoklren, OSTP John Hoklren, OSTP “Of all the outputs of forests, “Of all the outputs of forests, water may be the most important” National Academy of Sciences 2008 National Academy of Sciences 2008

Expected Climate Change Effects Precipitation: more rain & less snow Precipitation: more rain & less snow 33% snowpack loss 33% snowpack loss 1.6 °C increase by 2060 (Knowles 2002) 1.6 °C increase by 2060 (Knowles 2002) Earlier snowmelt Earlier snowmelt Faster snowmelt Faster snowmelt

Predicted Loss of Snowpack (Knowles 2002) °C Increase % Snowpack Loss Year (43 to 66)* 2090 * Effect greater in northern Sierra and Cascades ° 3 °C increase by (Bureau of Reclamation 2011)

Modeled Mean Annual Flow & Percent Decrease ( Null et al ) WatershedBasecasePercent decrease from Basecase 2° C increase6° C increase Feather Yuba Bear American Cosumnes Mokelumne Calaveras Stanislaus Tuolumne Merced San Joaquin Kings Kaweah Tule Kern

Animals VegetationSoilWater Bacteria & Fungus Nutrients & Carbon

Pacific Southwest Research Station, Fresno, CA Kings River Experimental Watersheds KREW

KREW Study: Paired Watershed Experiment

Annual Stream Discharge

Climate Change & Water Yield

Bull 203 Size: 342 acres Elevation: ft Mean Temp: 6.9°C Providence 303 Size: 327 acres Elevation: ft Mean Temp: 8.8°C

Water Cycle or Budget Atmosphere Transpiration by Vegetation Soil Streams & Lakes Evaporation Oceans

Findings: Water Yield & Climate Precipitation amount (30-80 in/year) Precipitation amount (30-80 in/year) Reaches maximum at 3,940 ft Reaches maximum at 3,940 ft Runoff ratio (discharge / precipitation) Runoff ratio (discharge / precipitation) 10% increase per 1,000 ft 10% increase per 1,000 ft Snow-dominated 2 to 3 times discharge Snow-dominated 2 to 3 times discharge Trees at rain-snow using more water in winter (evapotranspirtation 30 in) Trees at rain-snow using more water in winter (evapotranspirtation 30 in)

Upper Kings River Basin Goulden et al Measured evapotranspiration Measured evapotranspiration 10,000 ft 18 in/yr 10,000 ft 18 in/yr 6,600 ft 30 in/yr (60% higher) 6,600 ft 30 in/yr (60% higher) Due to winter dormancy at cold, snow dominated Due to winter dormancy at cold, snow dominated Both are mixed-conifer forest Both are mixed-conifer forest Atmospheric lapse is -5.3 °C per 3,300 ft Atmospheric lapse is -5.3 °C per 3,300 ft 3 °C warming shift vegetation upslope 3 °C warming shift vegetation upslope ET increase of up to 60% ET increase of up to 60%

Climate Change & Water Quality

Erosion: Roads & Wildfire Increased sediment yield because Increased sediment yield because Climate change = vegetation disturbance Climate change = vegetation disturbance Road maintenance and decommissioning effective but will not mitigate increase in sediment from increased wildfire Road maintenance and decommissioning effective but will not mitigate increase in sediment from increased wildfire Goode et al. (2012) Idaho case study Goode et al. (2012) Idaho case study

Findings: Flow Pathways Determined using water chemistry Determined using water chemistry Primary: Subsurface flow ~ 60% Primary: Subsurface flow ~ 60% Soil-bedrock interface Soil-bedrock interface Snowmelt runoff < 40% Snowmelt runoff < 40% Fall storm runoff < 7% Fall storm runoff < 7%

Adaptation: Multiple Stressors Air pollution Air pollution Increased wildfire Increased wildfire Insect outbreaks Insect outbreaks Climate change 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.” “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