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Title: Using terrestrial laser scanning to assess spatial correlation of peatland microform structure and conifer species in a whole-ecosystem warming experiment
Abstract: Peatlands are a globally ubiquitous wetland ecosystem type characterized primarily by a water table at or near the soil surface. In saturated conditions, partially decomposed plant material is sequestered in the soil substrate, becoming peat. Northern boreal peatlands (NBPs) contribute disproportionately to the global carbon stock. Northern peatland sites are populated by sphagnum moss, ericaceous shrubs and conifer species Picea mariana and Larix laricina. The sphagnum surface has high spatial heterogeneity due to differences in relative water table depth and geochemistry. This variation, called microtopography, leads to the formation of microform structures known as hummocks and hollows. Autogenic feedbacks between vegetation and microform structure have previously been studied in peatlands. However, the relationship between peatland microtopography and conifer distribution and morphology is under-represented in the literature. Furthermore, the effect of climate pressures on ecohydrological relationships is poorly understood. The D.O.E. Spruce and Peatland Responses Under Changing Environments (SPRUCE) experiment is a whole ecosystem warming experiment located on the Marcell Experimental Forest in northern Minnesota. 12.8 m diameter plots were constructed around sections of peatland to administer warming treatments of 0°C to 9°C. Each warming treatment is subject to baseline CO2 concentration or a CO2 enrichment of roughly 900 ppm. This study addresses the following questions 1) How does microform structure relate to conifer distribution in NBPs? 2) What are the effects of elevated temperatures and CO2 levels on conifer-microtopography relationships? Terrestrial lidar data was used to answer questions of spatial correlation and structure. Lidar data was collected using a Riegl VZ1000 Terrestrial Laser Scanner (TLS) with a wavelength of 1550 nm and angular resolution of 0.04°. Lidar scans were acquired in spring and late summer since 2015 to capture pre-photosynthetic and peak growing season vegetation. The raw point cloud data was merged and georegistered for analysis. I will present our preliminary findings on the relationship between microtopography and conifer distribution, and the effect of whole ecosystem warming and CO2 enrichment on these relationships.
Advisor: Nancy Glenn
Committee: Jim McNamara, Megan Cattau