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Kobayashi, Hideki*; Suzuki, Rikie*; Yang, W.*; Ikawa, Hiroki*; Inoue, Tomoharu*; Nagano, Hirohiko; Kim, Y.*
Polar Data Journal (Internet), 2, p.14 - 29, 2018/11
The Arctic and boreal regions have been experiencing a rapid warming in the 21st century. It is important to understand the dynamics of boreal forest at the continental scale under the climate and environmental changes. While the role of understory vegetation in boreal forest ecosystems on carbon and nutrient cycling cannot be ignored, they are still one of least understood components in boreal ecosystems. Spectroscopic measurements of vegetation are useful to identify species and their biochemical characteristics. In this data paper, we present spectral reflectances of 44 typical understory formations and five 30-m long transects. The spectral reflectance covers the spectral region of visible, near infrared and shortwave infrared (350-2500 nm). For the transect measurements, we decided the length of transect at 30 m, similar to the scale of one pixel of a Landsat type satellite imagery. The photographs at all positions, where spectral reflectances were obtained, are included to understand the structure and status of each sample. The data set contains six dwarf shrubs (blueberry (
), cowberry (
), feltleaf willow (
), young birch (
), young aspen (
), and young black spruce (
)), two herbaceous (cottongrass (
) and marsh Labrador tea (
)), three mosses (Sphagnum moss, splendid feather moss (
), and polytrichum moss (
)), and reindeer lichen (
). Spectral reflectances from several non-vegetative such as snow, litter, and soil are also included. This spectral and photographic data set can be used for understanding the spectral characteristics of understory formations, designing newly planned spectral observations, and developing and validating the remote sensing methodology of large scale understory monitoring.
Saito, Kazuyuki*; Iwahana, Go*; Ikawa, Hiroki*; Nagano, Hirohiko; Busey, R. C.*
Geoscientific Instrumentation, Methods and Data Systems, 7(3), p.223 - 234, 2018/07
Times Cited Count：2 Percentile：8.73(Geosciences, Multidisciplinary)A fibre-optic DTS (distributed temperature sensing) system using Raman-scattering optical time domain reflectometry was deployed to monitor a boreal forest research site in the interior of Alaska. Surface temperatures range between -40
C in winter and 30C in summer at this site. In parallel experiments, a fibre-optic cable sensor system (multi-mode, GI50/125, dual core; 3.4mm), monitored at high resolution, (0.5m intervals at every 30min) ground surface temperatures across the landscape. In addition, a high-resolution vertical profile was acquired at one-metre height above the upper subsurface. The total cable ran 2.7km with about 2.0km monitoring a horizontal surface path. Sections of the cable sensor were deployed in vertical coil configurations (1.2m high) to measure temperature profiles from the ground up at 5mm intervals. Measurements were made continuously over a 2-year interval from October 2012 to October 2014. Vegetation at the site (Poker Flat Research Range) consists primarily of black spruce underlain by permafrost. Land cover types within the study area were classified into six descriptive categories: relict thermokarst lake, open moss, shrub, deciduous forest, sparse conifer forest, and dense conifer forest. The horizontal temperature data exhibited spatial and temporal changes within the observed diurnal and seasonal variations. Differences in snow pack evolution and insulation effects co-varied with the land cover types. The apparatus used to monitor vertical temperature profiles generated high-resolution (ca. 5mm) data for air column, snow cover, and ground surface. This research also identified several technical challenges in deploying and maintaining a DTS system under subarctic environments.
