We addressed the following questions: (i) How well do native tree species regenerate on clearfelled upland conifer plantations? (ii) How does regeneration on clearfelled conifer plantations compare to regeneration on improved farmland and open moorland? (iii) What are the dominant factors controlling regeneration? (iv) How does the ground flora develop in the years following clearfelling and how does this impact tree regeneration? We surveyed a total of PD-1/PD-L1 inhibitor 2 21 sites at 4 different upland locations: Hardknott forest and Rainsbarrow wood in the Lake District,
north-west England and Clashindarroch forest and Bin forest in Aberdeenshire, north-east Scotland. All forests surveyed were managed by the Forestry Commission. The soil type, obtained from Forestry Commission soil maps, was used to predict the natural woodland community that would be expected to develop (Rodwell ABT-737 purchase and Patterson, 1994). Details of the sites selected are given in Table
1 and locations are shown in Fig. 1. Hardknott forest was planted on upland moorland between 1940 and 1955 (N. Williams 2008, Forestry Commission, personal communication). There are several broadleaf woodland fragments of Quercus spp. (oak spp.), Betula spp. (birch), Sorbus aucuparia (rowan), Ilex aquifolium (holly) and Salix spp. (willow). Nearby Rainsbarrow woodland was planted with conifers between 1959 and 1962 and is designated as a Planted Ancient Woodland Site (PAWS) ( Thompson et al., 2003). PAWS are sites with a long history of forest cover, with the original semi-natural woodland cleared and replaced by a plantation, a practice that was widespread in the UK before around 1980 ( Thompson et al., 2003). Clashindarroch forest was established from 1930 onwards ( Forestry Commission, 1964). Prior to afforestation, the Fossariinae land was mostly upland moorland with a dense flora of Calluna vulgaris (ling heather) and Vaccinium myrtillus (bilberry) with limited areas of Pteridium aquilinium (bracken) on the lower elevations ( Forestry Commission, 1952). Bin forest was established from 1926
onwards when most of the land was upland moorland with dense ling heather vegetation ( Forestry Commission, 1964). Both Clashindarroch and Bin forests retained small fragments of semi-natural woodland consisting largely of birch and rowan as well as Alnus glutinosa (common alder) and willow on the wetter ground. At these 4 locations we surveyed 15 sites that had been afforested with conifers, clearfelled and then left to regenerate naturally. Table 1 details the species of the felled conifer crop, which was generally dominated by Picea sitchensis (Sitka spruce), matching the dominant conifer species used across Britain ( Forestry Commission, 2012). The harvesting residues, known as brash, were typically windrowed – that is, gathered into regularly spaced linear mounds known as brash mats or windrows.