Buildings and roads cover 45% of Dublin City. In The Phoenix Park they cover only 7%. Almost the entire Park consists of green areas which are excellent for wild plants and wildlife. There are twenty four different habitats (places where wild plants and animals live). Woodlands and tree dominated areas cover 31% or 220ha and grasslands cover 56% or 398ha. Habitats include six types of woodland, five types of grassland, as well as hedgerows, scrub, ponds, streams and wet ditches.
Most of the grasslands in the Park were grazed and topped until the 1970’s. Since then, with the removal of hay the diversity of these grasslands has been improving. Extensive open areas of grassland such as the “Fifteen Acres” provide nesting sites for skylark. Grasslands, which are remote from the main thoroughfares, are not cut and thus provide food and shelter for invertebrates and cover for small animals. A rare type of grassland is found on the steep terraces on the south side of the Park. It has numerous colourful wild herbs including the rare and protected plant, Hairy Violet. Small areas of wet grassland, indicated by the presence of rushes, are found particularly near Oldtown Wood. In one of these is found another rare and protected plant, the grass meadow barley.
Important features of habitat biodiversity within The Phoenix Park include:
- High cover of “wood pasture”. This is a type of woodland not well described in Ireland. It is associated with the use of the Park by deer. Its quality depends on age of trees and presence of rare invertebrates.
- Semi-natural habitats, which are rare in Ireland. As well as wood pasture they include:
o Species rich calcareous grassland along sand and gravel terraces in the south of the Park, the flora of which includes Hairy Violet, a protected species.
o Wet grassland, particularly south of the Quarry Lake where the flora contains another protected plant, the grass meadow barley.
o Semi-natural woodland (0.5ha) dominated by ash near the Furry Glen.
o Fringing wetland vegetation around the Fish Pond (now in the Dublin Zoo).
- Presence of semi-natural habitats, which are rare in Dublin. These include almost all the other remaining habitats in The Phoenix Park, wetlands, other woodlands, and grasslands with the exception of buildings, built surfaces and amenity grassland.
Important features of native floristic diversity within The Phoenix Park include the Hairy St John’s Wort, on the edge of cleared woodland in the grounds of Áras an Uachtaráin; Hairy Violet, on the sand and gravel terraces at the south of the Park and the grass Meadow Barley in the wet grassland near the outfall from the Quarry Lake. The former was not seen in the Park since the 18th century. Hairy Violet has been seen in previous decades, is in decline, but no previous record has been made for the grass.