Tuesday, September 19, 2017

Signs of Spring

Whether you adhere to the Vivaldi option of four seasons or the Entwisle five, the signs of change are in the bush at last.

Professor Tim Entwisle, the director of the Royal Botanic Gardens of Victoria, has proposed that in Australia we should consider replacing the traditional European four season concept with a more applicable five – Sprinter (August and September), Sprummer (October and November), Summer (December to March), Autumn (April and May), and Winter (June and July).

Right now in the bush, the Winter orchids are withering; many birds are nesting; and the early flowering plants are beginning to bloom.

A case in point is evident at the nearby Thornells Reserve. Clematis (aristata I think), and Wonga Vine (Pandorea pandorana), are flowering in abundance at present.

Clematis aristata or Old Mans Beard
Pandorea pandorana - Wonga Vine
 Amongst the acacias, a few plants of prickly Moses are a standout right now.

Prickly Moses - Acacia verticillata
 Both species of Pardalote, Striated and Spotted, are calling incessantly and the Yellow-faced, White-naped and White-eared Honeyeaters are busy attending to various flowering eucs and acacias in the reserve.

White-naped Honeyeater
 Most birdwatching 'tragics' will have a favourite harbinger of Spring species – the first Cuckoo, Oriole or Rufous Whistler, etc - and Thornells is a great place to observe the first Summer migrants to arrive.

Note: Friends of Drouin's Trees will be conducting their second bird survey of Drouin in late October. If you would like to join us and help out, or just come along and see some of Drouin's wonderful avifauna, please contact Peter at drouinwaresATgmailDOTcom for details.

Friday, August 25, 2017

Trees and Development - Can They Coexist?

Drouin's trees play an important role in defining our town. The social, environmental, economic and aesthetic values of Drouin's trees are important to the community.

There is no shortage of evidence that shows access to natural environments are important for health and well-being.

Development cannot be halted, but sensitive strategies need to be employed in order to ensure our town retains as much as possible of one of its best assets – the trees.

A sea of rooftops
Sensitive development will require the cooperation of many bodies – the developer, the Shire and local authourities, the neighbours, the architects, the contractors, etc.

Many of Drouin's magnificent trees are remnants of the forests that originally stood here and their preservation is vital in providing the environmental, economic and aesthetic values they offer.

Compaction, trenching, pruning and removal are all activities that can seriously affect the tree cover during development.

Removing 'all' the trees in an area can completely unbalance the ecological factors, change the microclimate, raise the ambient temperature, increase erosion, etc.

Removing 'just one or two' trees is not wise either in many circumstances. Trees structurally support one another and removing even a single tree from a group can cause a decline in the remainder.
Worth saving?
Wise developers are aware that retaining tree cover provides immediate aesthetic and economic benefits, reduces site preparation costs, generates good relationships with the neighbours, authourities and the public in general.

90+ homes and no trees?
In an increasingly urbanized town, the focus on sustainable development is more important than ever and the complex relationship between environmental, economic and social processes needs particular attention.

Should the community allow private profit to destroy Drouin's special urban tree cover?

Saturday, August 12, 2017

Bark - Essential for Survival

A good illustration of the importance of bark is given by a growing tree that has a completely hollow trunk. The inner trunk may have been burned out, rotted, or decayed by insects such as termites. Just below and protected by the bark are three layers, the phloem, the cambium and the xylem, that are like pipelines carrying supplies to enable such a tree to keep growing.

Rotten to the core but still growing strong
The cambium, the second and thinnest layer, is the most important as it provides all the cells that form the trunk and branches.

Just outside the cambium, immediately under the bark, is the phloem. Made up fibrous material, the phloem transports sugars from the leaves down to the root system.

The xylem starts just inside the cambium and consists of the sapwood and heartwood. The sapwood carries water from the roots up to the foliage. The heartwood consists of layers of old sapwood.

(The transportation of water and nutrients up and down a tree is what enables a tree to grow and is a topic for another day)

The outer layer of bark is much like our skin. It protects the inner layers from damage and insect attack and trees with thick bark, like ironbark species, are even insulated from attack by fire.

Eucalypt bark protects the outer layer of sapwood that contains epicormic buds. When a eucalypt loses its crown in a fire, these buds will survive and produce green foliage that enables the tree to continue to live. (Eucalypts and fire is also a topic for another day)

Epicormic shoots on eucalypts appear after a fire
The bark of many trees contains resins that exude out when the tree is damaged, sealing off the area from further harm such as invasion by insects and fungi. It is now understood that the inner layers of bark also sequester carbon.

The bark on the trunk and branches of a tree also provides habitat for a host of organisms, giving rise to entire micro-ecosystems that are vital for the biodiversity of a region. Many insects and spiders, reptiles and mammals make their homes on and inside the bark of a tree. Moss, lichen and fungi species have adapted to growing on bark.

This well camouflaged Two-tailed Spider is a typical bark-dweller
 Many birds are especially adapted to extract a diet just from the animals that live there.

The Varied Sittella has long toes and a thin bill to help capture invertebrates in the bark of trees

White-throated Treecreeper - another bark specialist
The humble layer of bark on a tree plays a vital role in the survival of the tree itself and the health of the ecosystem in which it exists.