Remote sensing using spectral data has been commonly applied to retrieve tree layer properties while the monitoring of forest floor remains a less studied topic. We investigated the links between light availability at forest floor, and forest floor's spectral reflectance properties (350–2500 nm) and fractional cover across boreal and temperate Europe. We hypothesized that tree canopy structure (and thus, light availability at forest floor) is linked not only to the vegetation composition of forest floor, as has been shown previously, but also to forest floor's spectral reflectance properties, and that these relationships differ between forest biomes. Data were collected in situ from a total of 67 forest stands in southern boreal, hemiboreal, temperate floodplain, and temperate mountain sites. The variation of light availability at forest floor was linked to both the forest floor's composition and spectral reflectance properties. Each study site exhibited site-specific spectral features and a different mean reflectance spectrum. Openness in tree canopies was related to an increase in the fractional cover of vascular plants and to a decrease of plant litter, consequently enhancing the forest floors’ spectral absorptance features in the red and shortwave-infrared wavelengths, as well as reflectance in the near-infrared region. Also, the variations of normalized difference index values and red edge positions as functions light availability at forest floor and forest floor's composition were different for each site. Our results suggest that incorporating biome-specific relationships between tree canopy structure and forest floor reflectance properties would improve interpretation of optical remote sensing data. The measurement data are openly available.

使用光谱数据的遥感通常用于检索树层属性，而森林地面的监测仍然是一个研究较少的主题。我们研究了森林地面的光可用性与森林地面的光谱反射特性（350–2500 nm）以及北欧和温带欧洲的部分覆盖之间的联系。我们假设树冠结构（以及森林地面的光照可用性）不仅与森林地面的植被组成相关，如前所述，而且还与森林地面的光谱反射特性相关，并且这些关系在森林之间不同生物群系。从南寒带、半寒带、温带漫滩和温带山区的 67 个林分现场收集数据。森林地面可用光的变化与森林地面的成分和光谱反射特性有关。每个研究地点都展示了特定地点的光谱特征和不同的平均反射光谱。树冠的开放度与维管植物覆盖率的增加和植物凋落物的减少有关，从而增强了森林地面在红色和短波红外波长中的光谱吸收率特征，以及近红外波段的反射率红外区。此外，归一化差异指数值和红边位置作为森林地面光可用性和森林地面成分的函数的变化对于每个站点都是不同的。我们的结果表明，结合树冠结构和森林地面反射率特性之间的生物群落特定关系将改善光学遥感数据的解释。测量数据是公开的。