Envir ONF Bugey - Basal area of large woods (Bugey)

**Contact point** Basal area of large woods in m2 per hectare (m2/ha) Bugey sector partially superimposed with the data Basal area of large woods Bellegarde sector, Gex country. [link to description pdf](https://carto.ain.fr/webapps/external/doc/ONF_notice_modeles_LiDAR_v2.pdf) 1 - Modelling principles These models are built from the detection of apex identified on the digital height model from LiDAR covers. Only heights greater than 13 meters associated with bowls of more than 5 square meters are preserved. Treatment is carried out excluding the "unforested" type of IFN stand mapping v.2. Each apex is classified as hardwood or softwood based on the slopes of its crown and its reflectance measured on SPOT 6 images. Diameters at 1.30m and increments are estimated by apex-associated bowl characteristics. Attention new flow URL carto.ain.fr becomes geodata.ain.fr At the 26.5m side pixel scale, the predicted earth surfaces for each tree are summed by essence and diameter categories. Models applied to apex and pixels are calibrated using forest observatory plots. They are validated on a new set of 240 plots of 15 meters radius measured in 2015 and independent of the calibration set. 2 - Validity of modelled parameters The results obtained are corrected according to linear models. These stands are for example larch plantations, cochet pine forests, young thinned leafy futaies ... The validity in stand of black or Scots pine forests has not been verified. In general, the validity of the modelled parameters is not known for rare and atypical stands at the Ain mountain scale. 3 - Precautions for performing calculations from raster data For basal area, production, stem density, stand types, the zero value shall be used in the absence of data. All data are for a pre-count diameter of 17.5 cm to 1.30m (unless otherwise stated). For stand types, zero is a non-pre-accounting stand, or a non-forested area. These cases correspond either to stands less than 13 metres high (consisting a priori of trees with a diameter of less than 17.5 centimetres) or to a type of non-wooded IFN stand. Edge pixels integrate on a part of their surface a non-wooded area. In the event that the extraction area incorporates such pixels, it is important to apply a negative buffer to the extraction surface that will exclude its points. Predictive mapping of forest parameters of the Ain mountains, Office National des Forêts, A. Munoz, S. Dumas, 2017