MOSSAIC: MOSS Analysis Image Collection

[Material and methods] In this experiment six ground moss species were utilized. • Ptychostomum capillare (Hedw.) D.T. Holyoak & N. Pedersen [== Bryum capillare Hedw.] • Dicranum scoparium Hedw. • Homalothecium aureum H. Rob. • Hypnum cupressiforme Hedw. • Tortella squarrosa (Brid.) Limpr. [== Pleurochaete squarrosa (Brid.) Lindb.] • Syntrichia ruralis (Hedw.) F. Weber & D. Moh. For the moss stand inoculation, seedbed pots with synthetic wadding as the growth substrate were used. The experimental units were placed in three different locations along a 100-kilometer altitudinal gradient in Central Spain, specifically at: • Estación Biológica “El Ventorrillo” (VENT), Madrid, Spain (1482 meters above sea level - m.a.s.l.) • Universidad Autónoma de Madrid (UAM), Madrid, Spain (717 m.a.s.l.) • Finca Experimental “La Higueruela” (HIG), Toledo, Spain (455 m.a.s.l.) The pictures were captured using two Mapir Survey 2 cameras (https://www.mapir.camera/). One camera had an RGB sensor for visual wavelengths, while the other had a Red + NIR sensor for near-infrared. The manufacturer adjusted the focal distance to approximately 25 cm from the samples. Both cameras were equipped with a 16MP Sony Exmor IMX206 sensor, featuring a Bayer RGB pattern. The red absorption occurred at 660 nm, and near-infrared was captured at 850 nm. We employed a transparent plastic light diffuser box with an interior lining of white paper, such as filter paper. This setup served to even out the lighting and reduce the appearance of harsh shadows. Each image included the samples, a colour chart (specifically, the X-Rite ColorChecker® Classic) for calibration, as detailed in prior works (Ritchie et al., 2008; Fischer et al., 2012), and a millimetre scale for calculating the pixel-to-millimetre ratio. Moss samples were labelled in each hollow. The cameras saved the images in raw format and we converted it to tif format without compression using Darktable 2.6.1 software (https://www.darktable.org/) (‘Darktable’, 2019). Then we used ImageJ software (Schindelin et al., 2012) to align each pair of NIR-VIS images and to homogenize colour histograms for each VIS and NIR image series in each locality. The ImageJ scripts are provided by Photomoss protocol (Molina-Bustamante et al., 2022).