|OLSOY, PETER - Idaho State University|
|GLENN, NANCY - Boise State University|
|DERRYBERRY, DEWAYNE - Idaho State University|
Submitted to: Journal of Photogrammetry and Remote Sensing
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/20/2013
Publication Date: 1/14/2014
Citation: Olsoy, P.J., Glenn, N.F., Clark, P., Derryberry, D.R. 2014. Aboveground total and green biomass of dryland shrub derived from terrestrial laser scanning. Journal of Photogrammetry and Remote Sensing. 88C:166-173. DOI: 10.1016/j.isprsjprs.2013.12.006.
Interpretive Summary: Quantifying aboveground biomass of sagebrush across extensive landscapes is important for assessing global carbon storage and habitat quality of sagebrush dependent wildlife but existing field techniques are prohibitively expensive and airborne techniques lack adequate sample resolution. Ninety-one sagebrush plants were scanned with a terrestrial laser scanner (TLS) and sampled as a time series at three study sites in Idaho, USA in 2012. About half of the plants were scanned and then destructively sampled in the spring (n=46), while the other half were scanned again in the fall before destructive sampling (n=45). A 3-D convex hull model estimated total and green biomass more accurately (R2 = 0.92 and R2 = 0.84) than a voxel-based method (R2 = 0.87 and R2 = 0.70), respectively. Considering the potential listing of sage grouse under the Endangered Species Act, the results of this study are important for use in understanding and monitoring sagebrush health and distribution over extensive scales and for tracking seasonal growth changes that can impact sage grouse forage and habitat use.
Technical Abstract: The distribution of many dryland vegetation species are expected to shift based on predictions of future increases in global temperatures. Quantifying aboveground biomass in dryland systems is important for assessing global carbon storage and monitoring the presence and distribution of these rapidly changing ecosystems. Sagebrush (Artemisia tridentata), a dominant shrub species in the sagebrush-steppe ecosystem, is declining from its historical distribution due to feedbacks between climate and land use change, fire, and invasive species. Models of shrub canopy volume, derived from terrestrial laser scanning (TLS) point clouds, were used to accurately estimate aboveground shrub biomass. The latter set of sagebrush plants was scanned during both spring and fall to quantify seasonal changes in green biomass. In addition to the time series dataset, thirty more sagebrush plants that were scanned and sampled in October 2011 were also included in this analysis (total n=121). Sagebrush canopy volumes were estimated using both a voxel and a 3-D convex hull approach applied to TLS point cloud data. The 3-D convex hull model estimated total and green biomass more accurately (R2 = 0.92 and R2 = 0.84) than the voxel-based method (R2 = 0.87 and R2 = 0.70), respectively. Seasonal differences in green biomass were detected at one of the sites (P < 0.001), elucidating the amount of ephemeral leaf loss in the face of summer drought. Considering the potential listing of sage grouse under the Endangered Species Act, the results of this study are important for use in understanding and monitoring sagebrush health and distribution over larger scales, and seasonal growth changes that can impact sage grouse forage and habitat use.