The remnant bushland is confined largely to steep valley slopes adjoining two major creeklines and has significant scenic, environmental and biodiversity values with a large range of habitats. Coachwood dominated rainforest exists along the creeks with heaths and woodlands on the ridges and slopes. These vegetation communities provide habitat for fauna, including threatened species. Allenby Park has been heavily impacted on through stormwater runoff, encroachments, dumping of garden refuse and household rubbish, tree removal and poisoning, which has contributed to the degraded condition of the vegetation in certain areas. Professional bush regenerators have been working in the park since 1990.
Volunteers continue to work in the park as well.
They will also continue the planting of native tubestock and maintenance weeding as well as liaising with Park users, adjacent residential neighbours and interest groups to educate and gain co-operation in the management of the reserve. Why Escarpment is an area dominated by a coastal heath community typically associated with Hawkesbury sandstone. Council has employed professional bush regenerators for Dee Why Escarpment since 1991 while volunteers have worked the area for approximately 5 years. A section of the Bicentennial Coastal Walkway that stretches from Manly to Palm Beach passes through the area and is used heavily. Past activities such as clearing for housing developments, dumping, stormwater overflow, tree and native tubestock removal to enhance views and general unregulated entry have all contributed to the degraded condition of the vegetation in certain areas.