Biological soil covers: data on lichen, bryophyte and algae coverage in soils gathered by SoilSkin citizen science program using eBryoSoil app for smartphones

Biological soil covers (BSC) are small-sized topsoil communities composed mainly by lichens, bryophytes and algae that cover the terrestrial surface and play an essential role in maintaining the quality of the soil. However, little is known about their distribution, conservation, and ecosystem functions. The SoilSkin citizen science project aims to expand the scientific knowledge about the distribution of biological soil covers as an important step to evaluate the vulnerability of soil ecosystems of the Iberian Peninsula in the face of global change. The project has a dedicated free of charge app for smartphones (eBryoSoil, available at Google Play https://play.google.com/store/apps/details?id=com.omarfiz.ebryosoil&hl=ca&gl=US) that is designed to obtain information about the coverage of the BSC communities. To use this app, users must select a sampling location and capture the three soil pictures required to complete a transect. These photographs are taken at a 27 cm distance from the soil, in a straight line with 15 meters of distance between each picture. After the acquisition of each image, users can quantify the coverage percentage of biological soil covers and select the type of habitat where the transect took place. The transect is complete when all three pictures and their respective information are uploaded. The data presented here contains the records from SoilSkin participants, which mainly include a characterization of the cover patterns of biological soil covers, the type of habitat and the coordinates where each record was taken. The data set is composed by 279 unique records taken by 37 unique users from 28/11/2019 to 12/12/2020, across the Iberian Peninsula. These records specifically detail the percentage of cover occupied by three types of lichen growth forms (crustose, foliose and fruticose); liverworts; two types of moss growth forms (acrocarpous and pleurocarpous); algae; and soil. Moreover, each record also contains a description of the main type of habitat where the transect took place, that was selected from a list contained in the app with the following habitats: Dense forest - Habitat characterized by trees of more than 2 meters tall and canopy over 60%. Open forest – Habitat characterized by trees with more than 2 meters tall and a canopy below 60%. Shrubland – Habitat characterized by woody vegetation with less than 2 meters tall. Grassland – Habitat characterized by herbaceous plants. Agricultural land – Habitat characterized by temporary or woody crops. Coastal habitat – Habitat characterized by a landscape where land is in contact with the sea, creating a visibly different landscape from inner terrestrial one’s. Urban green spaces – Habitat characterized by a landscape in which man-made structures are present. The database was revised to correct any possible mistakes (e.g., miscalculation of total percentages; habitat missing in some registers; removal of invalid registers). The data file contains the following columns: Date: numerical variable indicating the “day”/”month”/”year” when the register was generated. User_ID: categorical variable with the identification number of the user who gathered the record. Transect: categorical variable with the identification of the number of the transect. Photo_number: numeric variable that takes values of 1, 2 or 3 and corresponds with the identification of the photographs within each transect. Photo_label: character string with the identification of the photograph from each record. Register_localization: categorical variable with the identification of the geographic area where the record was done. Latitude: integer, variable indicating the latitude of the sampling location in decimal degrees. Longitude: integer, variable indicating the longitude of the sampling location in decimal degrees. Accuracy: integer, variable indicating the accuracy of the coordinates given by the GPS. Habitat_type: categorical variable with the description of the main type of habitat of the sampling location. Lichen_Crustose: integer, variable indicating the percentage of crustose lichen cover quantified in the record. Lichen_Foliose: integer, variable indicating the percentage of foliose lichen cover quantified in the record. Lichen_Fruticose: integer, variable indicating the percentage of fruticose lichen cover quantified in the record. Total_lichen: integer, variable indicating the sum of all lichen coverage quantified in the record. Liverwort: integer, variable indicating the percentage of liverwort cover quantified in the record. Moss_Acrocarpous: integer, variable indicating the percentage of acrocarpous moss cover quantified in the record. Moss_Pleurocarpous: integer, variable indicating the percentage of pleurocarpous moss cover quantified in the record. Total_ moss: integer, variable indicating the sum of all moss coverage quantified in the record. Algae: integer, variable indicating the percentage of algae cover quantified in the record. Soil: integer, variable indicating the percentage of soil visible in the record.生物土壤结皮（Biological Soil Covers, BSC）是一类小型表层土壤群落，主要由地衣、苔藓和藻类构成，覆盖于陆地表面，对维持土壤质量发挥着至关重要的作用。然而目前学界对其分布、保护及生态系统功能的认知仍较为匮乏。 'SoilSkin'公民科学项目旨在拓展学界关于生物土壤结皮分布的科学认知，以此作为评估伊比利亚半岛土壤生态系统应对全球变化脆弱性的重要前置步骤。 该项目配备一款专属免费智能手机应用程序（eBryoSoil，可从Google Play获取：https://play.google.com/store/apps/details?id=com.omarfiz.ebryosoil&hl=ca&gl=US），用于采集生物土壤结皮覆盖度相关信息。用户使用该应用时，需选定采样点位并拍摄完成一条样带所需的三张土壤照片：拍摄时相机与土壤间距为27厘米，每张照片之间沿直线相距15米。每张图像采集完成后，用户可量化生物土壤结皮的覆盖百分比，并选定样带所在的生境类型。当三张照片及其对应信息全部上传后，即完成一条样带的采样。 本次发布的数据集包含来自SoilSkin项目参与者的采样记录，核心内容涵盖生物土壤结皮的覆盖特征、生境类型及每条记录的采集坐标。数据集共包含279条独立采样记录，由37位不同用户于2019年11月28日至2020年12月12日期间在伊比利亚半岛范围内采集完成。这些记录详细记载了三类地衣生长型（壳状地衣、叶状地衣和枝状地衣）、苔类、两类苔藓生长型（直立藓类和匍匐藓类）、藻类及土壤的覆盖百分比。此外，每条记录还包含样带所在的主要生境类型描述，该类型从应用内置的以下生境列表中选取： - 茂密森林：以树高超过2米、树冠覆盖率超过60%为特征的生境； - 疏林：以树高超过2米、树冠覆盖率低于60%为特征的生境； - 灌丛：以高度不足2米的木本植被为特征的生境； - 草地：以草本植物为优势的生境； - 农用地：以短期或木本作物种植为特征的生境； - 海岸生境：以陆地与海洋接壤、景观显著区别于内陆陆地的区域为特征的生境； - 城市绿地：以存在人工建筑的景观为特征的生境。 该数据库已经过审核修正，以排查并修正各类可能的错误（例如总覆盖百分比计算失误、部分记录缺失生境信息、移除无效采样记录等）。 数据文件包含以下字段： 1. Date：日期型变量，以「日/月/年」格式记录采样记录生成的时间； 2. User_ID：分类变量，用于标识采集该记录的用户编号； 3. Transect：分类变量，用于标识样带的编号； 4. Photo_number：数值型变量，取值为1、2或3，对应每条样带内照片的编号； 5. Photo_label：字符型变量，用于标识每条记录对应的照片； 6. Register_localization：分类变量，用于标识采样记录所在的地理区域； 7. Latitude：整数型变量，以十进制度数表示采样点位的纬度； 8. Longitude：整数型变量，以十进制度数表示采样点位的经度； 9. Accuracy：整数型变量，用于标识全球定位系统（GPS）的坐标精度； 10. Habitat_type：分类变量，用于描述采样点位的主要生境类型； 11. Lichen_Crustose：整数型变量，表示本次记录中壳状地衣的覆盖百分比； 12. Lichen_Foliose：整数型变量，表示本次记录中叶状地衣的覆盖百分比； 13. Lichen_Fruticose：整数型变量，表示本次记录中枝状地衣的覆盖百分比； 14. Total_lichen：整数型变量，表示本次记录中所有地衣类群的总覆盖百分比； 15. Liverwort：整数型变量，表示本次记录中苔类的覆盖百分比； 16. Moss_Acrocarpous：整数型变量，表示本次记录中直立藓类的覆盖百分比； 17. Moss_Pleurocarpous：整数型变量，表示本次记录中匍匐藓类的覆盖百分比； 18. Total_moss：整数型变量，表示本次记录中所有苔藓类群的总覆盖百分比； 19. Algae：整数型变量，表示本次记录中藻类的覆盖百分比； 20. Soil：整数型变量，表示本次记录中可见土壤的占比。