Analyzing tundra vegetation characteristics for enhancing terrestrial LiDAR surveys of permafrost thaw subsidence on yedoma uplands

• Main Authors: Veremeeva, Aleksandra A., Günther, Frank, Kizyakov, Alexander I., Grosse, Guido
• Format: Conference Object
• Language: unknown
• Published: Russian Academy of Science Institute of Physicochemical and Biological Problems in Soil Science RAS "Okabiolab" Ltd. 2019
• Subjects: Active layer thickness; Ice; lena delta; permafrost; Thermokarst; Tundra; Yakutia; Cotton-grass
• Online Access: https://epic.awi.de/id/eprint/51215/; http://cryosol.ru/images/phocagallery/conference/cryospherepuzzles/PushchinoPermafrost_ConferenceProgrammAbstracts2019_compressed.pdf; https://hdl.handle.net/10013/epic.7170f1fa-21bf-4398-bf54-80b0e371c18e

Surface subsidence is a widespread phenomenon in Arctic lowlands characterized by permafrost deposits. Together with active layer thickness dynamics surface subsidence is an important indicator of permafrost degradation in climate warming conditions. Due to small changes of surface heights of several centimeters or less per year, high-resolution and high-accuracy data are necessary to detect thaw subsidence dynamics in tundra lowlands. An appropriate method to receive such data is repeat terrestrial laser scanning (LiDAR). However, for LiDAR data analysis, uncertainties connected with vegetation dynamics should be taken into account. The vegetation type and its succession reflect the microrelief features, resulting in an areal differentiation of surface heights changes. Depending on wetness, possible influences might result from moss-lichen cover and its thickness dynamics. In this study we present some results of the vegetation characteristics and dynamics in context of its impact on the terrestrial LiDAR investigations for thaw subsidence assessment on yedoma uplands. During expeditions to the Lena Delta and the Bykovsky Peninsula in Northern Yakutia in 2015-2016, repeat terrestrial laser scanning was conducted on yedoma uplands formed by very ice-rich Yedoma Ice Complex deposits. On the Bykovsky Peninsula, detailed vegetation descriptions of the main vegetation types were done including all species projective cover, cotton grass tussocks height and area sizes, moss-lichen thickness and ALT measurements. Subsidence was about 3.5 cm on average and is mostly observed on drained inclined sites with dwarf-shrub graminoid, cotton-grass, moss-lichen tundra, representing initial baydzherakhs (thermokarst mounds). Surface heave is observed mainly within bogged depressions with sedge, moss tundra. The average ALT was 39±4.1 cm and 32±5.6 cm in 2015 and 2016, respectively. However, the ALT significantly varies locally and depends on the vegetation type and species. Cotton grass leaves average length decreased from 14.4 ...