Over the past 10 years I have been studying Coastal Sandstone Plateau Rock Plate Heath for its resilience. I am particularly interested in the way plants grow on shallow soils around Sydney in this vegetation type. There is a wide variety of diversity in both flora an fauna in this heath. There are some special plant adaptions and symbiotic relationships that make these plants thrive in harsh conditions. Wherever plants grow there is a rich abundance of lichens, mosses and insects above the ground. The symbiotic relationships ensure moisture is retained and nutrients provided to sustain a growth. Below the ground fungal mycorrhizal associations are related to nutrient exchange with fungus benefiting from sugars created by plants photosynthesis. The plants benefit from the nutrients available from the huge surface area that fungal hyphae provide. When plants are under extreme stress, after a few months without rain some take a deep red colour in their foliage. This could be a defence mechanism which is often associated in red leaves and toxic compounds. Apart from field research my experiments included growing these plants in green roof modules over a 3 year period. I observed how species persist and thrive. On the ridge tops around Berowra plants will grow in 15mm of soil and are possibly decades old. I grew plants in trays 45mm deep with great results. Plants were grown from collected seed and cuttings, I included lichens and site soil to include fungus. It is my hope that emulating this vegetation type on our buildings that biodiversity, particularly birds will have their habitat enhanced in our urban environment.
There are many species, some include Leptospermum arachnoides, Calytrix tetragona, Gahnia aspera, Patersonia sericea and my favourite Micromyrtus blakelyi.
Green roof plant Baeckea brevifolia turning red in a dry summer period.
Green roof plants here is Baeckea and Casuarina nana growing in a mere 45mm depth of growing media for over 3 years in the same tray.