Dataset of understory reflectance spectra and fractional cover in a boreal forest area in Finland

The dataset includes forest floor spectral reflectance factors at wavelengths of 350–2500 nm, fractional cover data of forest floor, forest inventory data, and data on the light availability at forest floor (diffuse non-interceptance, DIFN) and tree canopy structure (effective plant area index, PAIe). The data were collected near peak growing seasons 2018–2019 in situ in total of 36 forest stands in Hyytiälä, Finland (61°50’N, 24°17’E). Each study stand represents a forest site (fertility) type: OMT (herb-rich), MT (mesic), VT (sub-xeric), or CT (xeric), based on Cajander’s theory of forest types [1]. The first spread sheet contains descriptions of the variables, second spread sheet the stand characteristics, and third the spectral data. Version history: This is Version 3 of the dataset, which was used, together with data from [6], in the study of Forsström et al. [2]. If using Version 3, please cite Forsström et al. [2, 3]. Version 2 had an indexing error that caused the spectral data to be in the wrong order. Do not use Version 2. Version 1 was used in Forsström et al. [4]. It did not include canopy structure data and applied slightly different preprocessing of the spectra. If using Version 1, please cite Forsström et al. [4, 5]. We thank Lauri Korhonen, Ville Ranta, and Daniel Schraik for collaboration. Data collection and preparation was supported by the Academy of Finland [BOREALITY, grant number 286390; and DIMEBO, grant number 3323004]; and by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme [grant agreement No 771049]. The article reflects only the authors’ view and the Agency is not responsible for any use that may be made of the information it contains. [1] Cajander, A.K., 1926. The theory of forest types. Acta Forestalia Fennica. doi:10.14214/aff.7193 [2] Forsström, P.R., Hovi, A., Juola, J., Rautiainen, M., 2023. Links between light availability and spectral properties of forest floor in European forests. Agricultural and Forest Meteorology. doi:10.1016/j.agrformet.2023.109481 [3] Forsström, P.R., Juola, J., Hovi, A., Rautiainen, M., 2024. Dataset of understory reflectance spectra and fractional cover in a boreal forest area in Finland. Mendeley Data, V3. doi:10.17632/2g9nkcdj53.3 [4] Forsström, P.R., Juola, J., Rautiainen, M., 2021. Relationships between understory spectra and fractional cover in northern European boreal forests. Agricultural and Forest Meteorology. doi:10.1016/j.agrformet.2021.108604 [5] Forsström, P.R., Juola, J., Hovi, A., Rautiainen, M., 2021. Dataset of understory reflectance spectra and fractional cover in a boreal forest area in Finland. Mendeley Data, V1. doi:10.17632/2g9nkcdj53.1 [6] Forsström, P.R, Hovi, A., Juola, J., Rautiainen, M., 2024. Dataset of tree canopy structure, understory reflectance spectra and fractional cover in hemiboreal and temperate forest areas in Estonia and the Czech Republic. Mendeley Data, V2. doi:10.17632/9dx32rszp8.2本数据集涵盖波长范围350–2500 nm的林地表层光谱反射率因子、林地表层覆盖占比数据、森林清查数据，以及林地表层光照可用性数据（漫射非截光率（diffuse non-interceptance, DIFN））和树木冠层结构数据（有效叶面积指数（effective plant area index, PAIe））。数据采集于2018-2019年的生长季盛期，实地采集自芬兰海蒂亚拉（Hyytiälä，61°50’N，24°17’E）的共计36个林分。依据卡扬德（Cajander）森林类型理论[1]，每个研究林分对应一类森林立地（肥力）类型：OMT（herb-rich，富营养型）、MT（mesic，中营养型）、VT（sub-xeric，亚干旱型）或CT（xeric，干旱型）。 本数据集包含三张电子表格：第一张表格为变量说明，第二张表格为林分特征信息，第三张表格为光谱数据。 ## 版本历史 本数据集为第3版，已与文献[6]的数据一同应用于Forsström等人[2]的研究。若使用第3版，请引用Forsström等人[2, 3]。第2版存在索引错误，导致光谱数据顺序错乱，请勿使用。第1版曾用于Forsström等人[4]的研究，未包含冠层结构数据，且对光谱数据采用了略有差异的预处理流程。若使用第1版，请引用Forsström等人[4, 5]。 ## 致谢与资助 本研究感谢劳里·科霍宁、维尔·兰塔与丹尼尔·施雷克的协作支持。数据采集与预处理工作得到芬兰科学院[BOREALITY项目，编号286390；DIMEBO项目，编号3323004]，以及欧盟“地平线2020”研究与创新计划下的欧洲研究理事会（ERC）[资助协议编号771049]的资助。本文仅代表作者个人观点，相关机构不对本文信息的任何使用承担责任。 ## 参考文献 [1] Cajander, A.K., 1926. 森林类型理论. 《芬兰林业学报》（Acta Forestalia Fennica）. doi:10.14214/aff.7193 [2] Forsström, P.R., Hovi, A., Juola, J., Rautiainen, M., 2023. 欧洲森林林下层光照可用性与光谱特性的关联. 《农业与森林气象学》（Agricultural and Forest Meteorology）. doi:10.1016/j.agrformet.2023.109481 [3] Forsström, P.R., Juola, J., Hovi, A., Rautiainen, M., 2024. 芬兰寒温带针叶林区林下层反射光谱与覆盖占比数据集. Mendeley Data，V3版. doi:10.17632/2g9nkcdj53.3 [4] Forsström, P.R., Juola, J., Rautiainen, M., 2021. 北欧寒温带针叶林林下层光谱与覆盖占比的关联. 《农业与森林气象学》. doi:10.1016/j.agrformet.2021.108604 [5] Forsström, P.R., Juola, J., Hovi, A., Rautiainen, M., 2021. 芬兰寒温带针叶林区林下层反射光谱与覆盖占比数据集. Mendeley Data，V1版. doi:10.17632/2g9nkcdj53.1 [6] Forsström, P.R., Hovi, A., Juola, J., Rautiainen, M., 2024. 爱沙尼亚与捷克共和国半寒带与温带林区树木冠层结构、林下层反射光谱及覆盖占比数据集. Mendeley Data，V2版. doi:10.17632/9dx32rszp8.2