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

Disturbance, Age Structure, and Carbon

Understanding the history of land use, management, and disturbance is critical because disturbance and recovery are major determinants of the net terrestrial carbon flux.” - 2007 SOCCR (SAP 2.2)

Biologic C Flux Biomass time Atmospheric source Old Disturbance Dominated Regrowth Dominated Balanced

Forest Disturbance and NACP

• 56 NACP project descriptions include “Disturbance” • NACP Disturbance Synthesis 2010-2011 (Kasischke) • JGR-B Special Section “Impacts of Disturbance on the North American Carbon Cycle” • Many new products, analyses

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 (1985-2005) • Disturbance events mapped using Vegetation Change Tracker (VCT approach) (Huang et al, 2010)

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

NAFD National Disturbance Rates estimates

1985-2005 average = 2.77 Mha/yr (+/- 0.76) = 1.1% US Forest Land Masek et al, in review

East versus West

East West

Western US

US Quadrants

Eastern US Central Coastal Southeast Northeast

2 1 0 5 4 3 9 8 7 6 Estimates of US Disturbance Rates Harvest (Smith et al, 2009) Fire (EPA, 2010) Insects (USFS, 2010) Western Insect Mortality (2005 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

Higher NAFD Disturbance = Lower NEP Estimate

Williams et al., in review

NAFD Phase III

0 %disturbed /yr >2.0

LEDAPS Disturbance Map 1990-2000 (

Masek et al., 2008)

• • • • • Annual Time Series (1972 -2012) 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)

Geography of Disturbance Causes

(No Insects yet)

Schleeweis , 2012

Conclusions

• US Forest Disturbance Rates estimated at 1.1%/yr from 1985-2005 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?)

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 .” 2007 SOCCR (SAP 2.2)

Attribution of Disturbance Variability Masek et al, in review

US Forest Biomass and C Storage Potential (PgC)

Williams et al., in review US forests could ~double current stocks

NAFD Staff & Collaborators

Liz LaPoint USFS FIA

University of Maryland (Goward, Huang)

Feng Zhou Research Associate Mary Ann Lindsey GRA Louis Keddell GRA Elaine Denning GRA

USFS PNW/OSU (Cohen, Kennedy)

Stephen Stehman Syracuse University Zhiqiang Yang Research Associate Peder Nelson GRA

USFS RMRS (Moisen)

Karen Schleeweis Todd Schroeder Chris Toney

NASA GSFC (Masek)

Chris Neigh Khaldoun Rishwami J. Collatz NASA GSFC

Collaborators

Bev Law OSU J. Dwyer USGS/EROS Z. Zhu USGS H. Bastian USGS