Spectral reflectance and associated photograph of boreal forest understory formation in interior Alaska

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 and to estimate the biophysical parameters such as understory leaf area index, above ground biomass. 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 (Bog bilberry (Vaccinium uliginosum), cranberry (Vaccinium vitis-idea), feltleaf willow (Salix alaxensis), young birch (Betula neoalaskana), young aspen (Pupulus tremuloides), and young black spruce (Picea mariana)), two herbaceous (cottongrass (Eriophorum vaginatum) and marsh Labrador tea (Ledum decumbens)), three mosses (Sphagnum moss, splendid feather moss (Hylocomium splendens), and polytrichum moss (Polytrichum commune)), and reindeer lichen (Cladonia rangiferina). 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.北极与寒带地区在21世纪经历了快速变暖。理解气候与环境变化下大陆尺度寒带森林的动态变化机制，具有重要的科学价值。 寒带森林生态系统中，林下植被在碳循环与养分循环中的作用不容忽视，但它们仍是当前寒带生态系统中认知程度最低的组分之一。植被光谱测量技术可用于物种识别、生化特征解析，以及估算林下叶面积指数、地上生物量等生物物理参数。 本数据论文公开了44种典型林下植被群落以及5条30米长样带的光谱反射率数据。该光谱反射率覆盖可见光、近红外与短波红外波段（350~2500 nm）。本次样带测量将样带长度设定为30米，该尺度与Landsat系列卫星影像单像素的尺度相近。在所有获取光谱反射率的采样点位均配有对应照片，用于直观呈现每份样品的群落结构与生长状态。 本数据集涵盖6种矮灌木：笃斯越橘（Vaccinium uliginosum）、蔓越莓（Vaccinium vitis-idaea）、毡毛柳（Salix alaxensis）、幼龄白桦（Betula neoalaskana）、幼龄山杨（Populus tremuloides）以及幼龄黑云杉（Picea mariana）；2种草本植物：羊胡子草（Eriophorum vaginatum）与沼泽杜香（Ledum decumbens）；3种苔藓：泥炭藓（Sphagnum moss）、塔藓（Hylocomium splendens）以及金发藓（Polytrichum commune），同时包含驯鹿地衣（Cladonia rangiferina）。此外，数据集还收录了积雪、枯落物、土壤等非植被类别的光谱反射率数据。 本光谱与影像数据集可用于解析林下植被群落的光谱特征、为后续规划的光谱观测提供设计参考，以及开发并验证大规模林下植被监测的遥感方法。