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US Forest Disturbance Trends observed with Landsat Time Series Samuel N. Goward 1 (PI), Jeffrey Masek 2, Warren Cohen 3, Gretchen Moisen 4, Chengquan Huang.

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Presentation on theme: "US Forest Disturbance Trends observed with Landsat Time Series Samuel N. Goward 1 (PI), Jeffrey Masek 2, Warren Cohen 3, Gretchen Moisen 4, Chengquan Huang."— Presentation transcript:

1 US Forest Disturbance Trends observed with Landsat Time Series Samuel N. Goward 1 (PI), Jeffrey Masek 2, Warren Cohen 3, Gretchen Moisen 4, Chengquan Huang 1, Robert Kennedy 5, Karen Schleeweis 1, Rama Nemani 6 1 Department of Geography, University of Maryland, College Park MD 2 Biospheric Sciences Lab, NASA Goddard Space Flight Center, Greenbelt, MD 3 U.S.D.A. Forest Service, Pacific Northwest Research Station, Corvallis, OR 4 U.S.D.A. Forest Service, Rocky Mountain Research Station, Ogden, UT 5 Earth and Environment Dept., Boston University, Boston MA 6 NASA Ames Research Center, Moffett Field, CA

2 Biomass Biologic C Flux Atmospheric source Disturbance, Age Structure, and Carbon Old Disturbance Dominated Regrowth Dominated area histograms Balanced time Understanding the history of land use, management, and disturbance is critical because disturbance and recovery are major determinants of the net terrestrial carbon flux.” SOCCR (SAP 2.2)

3 56 NACP project descriptions include “Disturbance” NACP Disturbance Synthesis (Kasischke) JGR-B Special Section “Impacts of Disturbance on the North American Carbon Cycle” Many new products, analyses Forest Disturbance and NACP

4 North American Forest Dynamics (NAFD): Landsat-based sample of US forest disturbance 50 sample scenes across US; probability-based sample for area estimates (East, West strata) Annual time series of Landsat data for each sample ( ) Disturbance events mapped using Vegetation Change Tracker (VCT approach) (Huang et al, 2010)

5 Vegetation Change Tracker (VCT): Huang et al (2010) Example: Fire & Harvest, Sierra Nevada CA

6 NAFD National Disturbance Rates estimates % US Forest Cover Disturbed average = 2.77 Mha/yr (+/- 0.76) = 1.1% US Forest Land Masek et al, in review

7 East versus West % Forest Cover Disturbed West East

8 US Quadrants Western USEastern US Central Coastal Southeast Northeast

9 Insects (USFS, 2010) Fire (EPA, 2010) Harvest (Smith et al, 2009) Western Insect Mortality ( ) Forest Area Disturbed (Mha/yr) Estimates of US Disturbance Rates

10 US Forest Carbon Fluxes from Recent Disturbance (Williams et al., 2012 GBC; in review RSE) CASA calibrated to match FIA biomass-age curves for each forest type & region Landscape age distribution from FIA and NAFD time since disturbance Landscape-scale estimates of NPP, NEP, biomass based on age, type, region

11 Higher NAFD Disturbance = Lower NEP Estimate Williams et al., in review

12 NAFD Phase III Annual Time Series ( ) Wall-to-wall (440 * 40+ = > 17,000 annual maps) via NEX computing environment (Nemani – NASA ARC) Systematic Validation (Cohen – USFS PNW) Disturbance Causes (Moisen USFS RMS) Regrowth Dynamics (Masek – NASA GSFC) 0 %disturbed /yr LEDAPS Disturbance Map ( Masek et al., 2008) >2.0

13 Geography of Disturbance Causes (No Insects yet) Schleeweis, 2012

14 Conclusions US Forest Disturbance Rates estimated at 1.1%/yr from via NAFD Landsat analysis … but RS methods tend to miss considerable partial disturbance (thinning, insect mortality, storm damage) Overall disturbance rates varied by ~x2 during mapping epoch Western variability driven by fire, insects; Eastern variability driven by management (GDP?)

15 Forest Carbon Dynamics “The relative importance of these broad factors in accounting for the current [forest carbon] sink is unknown… Understanding the history of land use, management, and disturbance is critical because disturbance and recovery are major determinants of the net terrestrial carbon flux.” SOCCR (SAP 2.2)

16 Attribution of Disturbance Variability Masek et al, in review

17 US Forest Biomass and C Storage Potential (PgC) US forests could ~double current stocks Williams et al., in review

18 NAFD Staff & Collaborators

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