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Title: LiDAR-derived carbon estimates in encroaching juniper woodlands

item SANKEY, T - University Of Idaho
item SHRESTHA, R - University Of Idaho
item SANKEY, J - Us Geological Survey (USGS)
item Hardegree, Stuart

Submitted to: Trans American Geophysical Union
Publication Type: Abstract Only
Publication Acceptance Date: 9/4/2011
Publication Date: 12/13/2011
Citation: Sankey, T.T., Shrestha, R., Sankey, J., Hardegree, S.P. 2011. LiDAR-derived carbon estimates in encroaching juniper woodlands. Trans American Geophysical Union.

Interpretive Summary:

Technical Abstract: Woody encroachment is thought to contribute significantly to the global carbon (C) sink. The global- and continental-scale estimates of this contribution, however, have large uncertainties. The woody encroachment contribution to the C sink needs to be estimated at regional and local scales to address uncertainties as well as to balance restoration activities with greenhouse gas mitigation goals. We present a new technique to estimate aboveground C storage in distinct encroachment phases of juniper woodlands in the South Mountain watershed, southwestern Idaho, USA using 3-dimensional lidar measurements of individual juniper trees. We mapped and measured 2,613 juniper stems in 85 field plots. Lidar-derived juniper tree heights, canopy cover, and density were strongly correlated with field-measurements (R2 > 0.84, p < 0.001). The canopies of 60,628 individual juniper trees were identified via a segmentation approach. Aboveground biomass of the trees were then estimated using lidar-derived height and crown area (Adj. R2 = 0.76). The mean aboveground woody biomass was 13.53 Mg/ha with a mean aboveground woody C storage of 677 g/m2. At a broader scale, this would translate to a total C sink of 32,232 MgC across the juniper woodland distribution of 30 million acres in the USA when assuming a complete shift from sagebrush steppe vegetation to juniper woodlands. This technique could be applied to quantify changes in aboveground C, which in conjunction with estmates of belowground C pools are necessary to understand how woody encroachment alters the C pools and determine whether juniper.