Olivia Bartlett

2017-2018 NSHGC Fellow

Olivia is a PhD student in Natural Resources and Earth System Sciences at UNH.

Olivia's current research explores remote sensing approaches, combined with field validation measurements, to better understand relationships between forest growth and soil. She is measuring changes in tree growth and soil chemistry over time and distance in northern forests of New Hampshire. The health of our forests is intimately linked to the inputs they receive, as well as the stresses of land use change and forest harvesting. Even though acid rain has been reduced in the last couple of decades by pollution controls, its effects on exchangeable soil elements remain, resulting in the depletion of essential elements like calcium and magnesium. We see the combination of these effects as reduced growth and increased mortality in tree species such as red spruce and sugar maple. Soil health isn't just a matter for scientists to study: since it affects forest productivity (of interest in a heavily-forested state like New Hampshire), Federal land managers are also expected to study and track changes.

Monitoring forest soils in New England became increasingly important with noticeable impacts to forest health from acid rain in previous decades. However, the challenge for soil monitoring is disentangling heterogeneity at multiple spatial scales so variation occurring over space is not confounded with change across time (that is, figuring out whether the different distributions we see in a variety of locations is due to changes over time, or to their location relative to the water table and other inputs). Olivia’s current research includes resampling soils from forty permanent plots across the White Mountain National Forest (WMNF) that were established in the summer 2001 and 2002. The initial sampling design accounted for one soil pit to be dug at each site, and future, decadal re-sampling to occur two meters away on contour from the original soil pit. Olivia resampled soils by genetic horizon in 2014 as well as intensively sampling a subset of sites in 2015. This approach to estimate the variance components simultaneously at the landscape scale and at the within-plot is critical for calculating sample size and quantifying temporal rates of change.

Olivia's two-part research involves re-sampling soils as well as measuring trees from the permanent forest plots that were established in the WMNF. She is using airborne and terrestrial lidar (Light Detection And Ranging, a remote sensing technique that uses a pulsed laser to measure elevation) to explore relationships between tree growth and various soil properties. Digital soil mapping,b ased on the dominant hydrologic patterns influencing soil formation, overlay a lidar-derived DEMDigital elevation models (DEMs), representative of Earth’s bare surface, can be created from lidar to calculatetopographic metrics, such as slope, curvature, and topographic wetness index. Different measurements of slope can be used as factors explaining much of soil variability. Olivia is mapping soils from lidar-derived terrain indices to extrapolate field-validated soil properties across a landscape. Taken together, the data can improve both scientists' and land managers' understanding of biogeochemical processesto help predict forest changes.

Olivia is in training as a Biological Information Scientist with the US Forest Service, where she uses spatial data to assist in forest management and monitoring of a district-level National Forest. She also teaches advanced Geographic Information Systems and remote sensing courses at Plymouth State University since 2013. After graduation, Olivia would like to continue to research and teach about remote sensing applications for forest research and management.