These stands originated from plantations of Norway spruce (Picea abies (L.) Karst), Douglas fir (Pseudotsuga menziesii (Mirb.) Franco.) and, in two stands, silver fir (Abies alba Mill.) and Japanese larch (Larix Kaempferi (Lamb) Carr). The stands are additionally composed of Sorbus aucuparia L, Fagus sylvatica L., Western hemlock (Tsuga heterophylla (Ref.) Sarg.), Betula sp. and Pinus sylvestris L. that naturally regenerated or were preserved by past forest management. All these stands are in public forests managed with continuous cover forestry. Single tree selective thinnings or partial harvests are realized periodically (about every 6-12 years). Red deers (Cervus elaphus L.) and Roe deers (Capreolus capreolus L.) were present in the area but in limited abundance and causing relatively few browsing damages.
In each stand, the trees with diameters greater than 10 cm were mapped and their diameter is measured. Moreover, 12 circular subplots of 3 m radius were laid out systematically to monitor regeneration (density, height structure) and light conditions. These measures are repeated every two years.
In addition, in 2016, tree total height, the height of the base of the crown and crown radii were measured. In March-April 2018 and in October 2018, the three tallest saplings of each species were measured in each subplot. Their height, the length of the terminal shoots of years 2016, 2017 and 2018 were also measured, as well as the longest lateral shoots that was selected among the lateral shoots growing at the last whorl of the corresponding year.
Hemispherical photographs were taken in the centre of subplots, above regeneration, at dawn or dusk, in spring 2018 (Nikon D90, Sigma 4.5 mm fisheye lens).
Because the growth of saplings could have been affected by different pest and pathogens associated with defoliation symptoms, the foliage retention index was estimated. Considering the phytosanitary problems affecting Douglas fir in the study area, additional observations and analyses were performed to assess in more details the damages of pest and pathogens of Douglas fir regeneration.
In summer 2021, the floristic diversity, the abundance of tree microhabitats and deadwood were assessed in each stand.