They also constructed the stone walls around the landings and a swimming pool. Bach sites were leased to help pay for island developments. Some of these baches will be preserved as historic buildings. During World War II there were extensive defence installations on the island, including a fire command post on the summit. Biodiversity Rangitoto's lava rock seems an inhospitable environment for plant life, yet the island hosts over 200 species of native trees and flowering plants, more than 40 kinds of fern and several species of orchid.
Many plants form unusual hybrids or adopt strange behaviours because of the unusual conditions.
The crimson-flowered pohutukawa is Rangitoto's dominant tree. Once common along New Zealand coastlines, pohutukawa forests have been largely reduced to lone trees and Rangitoto has the country's largest remaining pohutukawa forest. The Department has successfully completed a major project to eradicate possums and wallabies which were destroying the island's pohutukawa. Now a major weed eradication programme is underway on the island. As they grow the pohutukawa provide shelter and shade for other species like mingimingi, koromiko and puka.