The bryoflora of the ash coppice of the Krengenbos and Lugtenakkers The Krengenbos (7 ha) and Lugtenakkers (2 ha) are two small sites with ash coppice wood, situated in the inner dune landscape of the province of Noord-Holland in the Netherlands, between Castricum and Heemskerk (Fig. 1). The Krengenbos was first noticed because of its interesting bryoflora by Barkman in 1941. Both woods have, by Dutch standards, a long history. The Krengenbos goes back to the second half of the 18th century, the Lugtenakkers existed already in the 17th century. The ash stools are up to 250 till 350 years old. Both woods were uninterruptedly coppiced, except for a period of neglect of the Krengenbos in the second half of the 20th century. Both copses have been formed under rather wet conditions. Since 1995, the Krengenbos has a much higher surface water level than the surrounding polder, as a result of hydrological isolation. The main tree is ash, though black alder, sycamore, white and grey willow also occur. The vegetation can be classified as Fraxino-Ulmetum. Since the first visit of Barkman, several epiphyte surveys were carried out; the results are summarized per decennium in Table 1. Until now a total of 57 species were recorded. Some species have been found only once, but 42 species appear regularly in recent times. The most characteristic epiphytes are confined to the bark of ash stools. Barkman recognized and described this as the moss community Anomodonto-Isothecietum (1958). Recently, this community has been revised and described as the Brachythecio populei- Anomodontetum viticulosi by van Dort & Weeda (2017). Key species are Anomodon viticulosus, Porella platyphylla, Homalia trichomanoides, Isothecium alopecuroides, Thamnobryum alopecurum, Brachythecium populeum and B. velutinum. Differentiating species are Neckera complanata and Homalothecium sericeum. This community is rare in the Netherlands, and its distribution is restricted to the dune and fluviatile districts. The best examples are recorded on stubs of ash which are regularly managed. Relevés representing this community within the Krengenbos and Lugtenakkers, are presented in Table 2 and compared with the original relevé by Barkman of the Krengenbos. One of the main differences with the first relevé is the lower number of total species; this is caused by the fact that Barkman used more than one stool for a single relevé. Compared with relevés made in the larger complexes of ash coppice (>20 ha) in the Rhine system, the total species number is also lower. Although most key species occur in the small copses, their frequency is very low, and it almost never happens that two or more of them are present on one and the same stub. Recently ashdieback (Hymenoscyphus fraxinea) has invaded Western Europe and causes severe damage to stands of ash. The ash coppice stands are very vulnerable, and the prospects are very bad: both woods here discussed, are already infected. Because ash copses are mainly monocultures, other tree species cannot easily colonize them; continuity of the treelayer is therefore doubtful. Shrubs and higher vegetation overgrow the dying ash stubs, this will inevitably lead to the disappearance of the Brachythecio populei-Anomodontetum viticulosi within the ash coppice woods. Recent records of the key species of this moss community outside its former strongholds are described, and some relevés are presented in Table 3. Although not well developed, fragments of the Brachythecio populei-Anomodontetum viticulosi are already present in the older and wetter high woodlands in the inner dune landscape of Noord-Holland. Scale and frequency are restricted so far, but nonetheless these records are encouraging. In addition to the development of older high stands of woodland, tree species with a neutral bark can be actively introduced within the ash coppice stands. Species like field maple, sycamore, European white-elm, white willow, offer also proper substrates for the bryoflora. After simultaneous introduction of species with a less neutral bark, the woodland community will be more diverse and less vulnerable to future pests and diseases.