the limestone. The wood has a low canopy of 6–14 m (20–46 ft). Yew's extreme tolerance of the dense shade its canopy creates has allowed it to outcompete other species to create the pure yew woodland present today. This dense shade prevents flowering plants from establishing themselves in these woods and prevents the herb layer from developing. Bryophytes are, however, abundant and thrive in humid and cool conditions. In some parts of the wood, there are continuous dense blankets of moss that can be up to deep. The moss species present are primarily Thamnium alopecurum with Eurhynchium striatum and Thuidium tamariscinum. Some of the trees in Re-enadinna wood are two hundred years old. There has been little regeneration of the yew trees in the wood. Overgrazing of the woodland floor by sika deer may be part of the reason for this, but small areas of the wood that have been fenced off since 1969 have experienced very little yew regeneration. The dense canopy created by the yew trees that lets very little sunlight through to the woodland floor may also prevent the growth of yew seedlings. Despite its poisonous properties, yew is very susceptible to browsing and bark stripping by deer, rabbits, hare, and domestic animals. It is one of the most grazing sensitive trees in the Killarney woodlands. sika deer have killed yews by scoring the trees with their antlers. Wet woodlands Wet woodland (also called carr) on the low-lying swampy limestone areas within Lough Leane's floodplain is about in size. This is one of the most extensive areas of this woodland type in Ireland. The dominant canopy species here are alder (Alnus glutinosa), ash (Fraxinus excelsior), downy birch (Betula pubescens), and willow (Salix spp.). The areas that are periodically covered by water are rich in species including grasses, rushes, sedges, and flowers such as marsh bedstraw, meadow sweet, and water mint. Red deer and sika deer heavily use the wetland woods as cover, and bare muddy "deer wallows" are a characteristic feature. Rhododendrons are the greatest threat to these woodlands. They are invading the woodlands, using raised areas such as tussocks or tree bases where the floor is too wet for seedlings to become established. Although some clearance has occurred reinvasion continues. Bogland While the lower slopes of the mountains are dominated by sessile oak (Quercus petraea), above the mountains are virtually treeless and are dominated by blanket