Category: Biology (Page 2 of 2)

Red gums sentinels to First Fleet arrival

August 4, 2017 / John Halkett

The only surviving eucalypts from the natural forest in the garden are two twin red gums perched up on the cliff behind the Opera House on the Bennelong lawn. No doubt they were mere saplings in 1788 when the 11 tall, wooden ships of the First Fleet arrived in Sydney. Incredibly, this Bennelong twins alone have survived so close to the city. Referring to them, Ashley Hay (Gum, 2002 Duffy & Snellgrove, Potts Point, NSW, Australia.) wrote:

The view from [its] crown began to change from the canopies of other eucalypts growing along the land’s ridges and streams, from clear distance running

Magnificent planted Queensland kauri at Blackburn Cove, eastern Sydney.

Kauri and monkey puzzle tree

February 25, 2017 / John Halkett

I have always had a soft spot for Agathis trees. This magnificent planted Queensland kauri (Agathis robusta) is adjacent to the beach on eastern Sydney where I occasionally go for a quick swim before work. It has to be well over a hundred years old – perhaps two hundred.
Together Agathis and Araucaria form the Southern Hemisphere conifer family of trees Araucariaceae. Agathis – a genus of thirteen species is generally known as kauri, after the Maori name for the New Zealand species Agathis australis.
Although the genus extends as far south as the warm temperate forests of northern New Zealand, … Read more “Kauri and monkey puzzle tree”

Main tree species in boreal forests are conifers – pines, spruces, firs and larches – adapted to very cold climatic conditions.

Boreal forests – it’s cold up there

February 25, 2017 / John Halkett

Boreal forests are one of the planet’s great ecosystems. Boreal (meaning northern – they are called taiga in Russia) forest occupies the northern sub arctic zone up beyond about latitude 50 encircling the Earth at the top of the Northern Hemisphere across Russia, Scandinavia, Alaska and Canada. The boreal forest belt represents the world’s largest land-based ecosystem and act as part of the largest source and filter of freshwater on the planet.
Temperatures in these boreal forests are usually extremely low with long winter seasons. The soil freezes – only thawing for a few months in the farthest… Read more “Boreal forests – it’s cold up there”

Northern trees disrobe for winter

November 16, 2016 / John Halkett

Just had a working visit to Brussels, and was it cold after the emerging summer temperatures in Sydney! The locals know how to dress for one digit temperatures – I just don’t own those sort of clothes.
The deciduous broadleaf trees in Brussels and elsewhere across the northern hemisphere are also transiting into their winter wardrobe. This means shedding their cloak of leaves. This feature of northern hemisphere broadleaf trees is only occasionally seen in the southern hemisphere.

As deciduous trees prepare for their annual leaf loss they absorb the chlorophyll, plus other nutrients from … Read more “Northern trees disrobe for winter”

‘Dinosaur’ pine growing in Sydney

October 19, 2016 / John Halkett

The Royal Botanic Gardens in Sydney is one of my favorite spots in the city. Recently I paid another visit and checked out the Wollemi pine. This specimen was planted as one of the first seedlings from the trees found growing in the wild.

The Wollemi pine was formally identified in 1994. It is an example of the botanical diversity and wonder of Australian trees. Discovered when bushwalker David Noble clambered down a rocky cliff into a remote canyon in the Wollemi wilderness – hence the name – about 100 kilometres inland from Sydney. He encountered a cluster of strange-looking trees that he had never… Read more “‘Dinosaur’ pine growing in Sydney”

Dr Lyndall Bull, director, Forestry Tasmania, and Cr Christine Sindt, Latrobe City, Victoria, congratulate John Halkett at the book launch at the Melbourne Outlook and Insights Conference.

Jungle book now available

September 14, 2016 / John Halkett

Billed as the Book of the Month for September Jungle Jive: Sustaining the forests of Southeast Asia takes a constructive look at jungle conservation, arguing that implementing economic measures that value jungle trees is the way to sustain them and their biological values. The central thesis of the book is the need to inject a dose of economic realism into a subject that has been long on superlatives and emotion, but short on commercial reality.
The book sets out an argument for that in part lies in the increasing prospects of sustainable, legally verified wood production and climate change abatement… Read more “Jungle book now available”

Stone pines amongst the remains of ancient Rome.

Stone pines – feature of Rome

May 24, 2016 / John Halkett

Just back from working in Rome. Many would say that the defining feature of the place is the colosseum and other ruins from Roman times. Sure they are impressive, but a more universal feature of the city is the extensive plantings of stone pine as street and decorative trees. These highly manicured trees give Rome a distinct look – more so in my opinion that the remnants of Julius Caesar and his mates.

Stone pine (Pinus pinea) also called Italian stone pine, umbrella pine and parasol pine is native to the Mediterranean region, occurring in Southern Europe, Israel, Lebanon and Syria. The tree has been… Read more “Stone pines – feature of Rome”

Joshua tree… sucking up water in California’s Mojave desert.

Trees grow almost anywhere – take the Joshua tree

March 17, 2016 / John Halkett

No doubt – trees are feats of architectural and engineering excellence among nature’s greatest achievements. Trees – and of course forests – are found in all regions of the Earth capable of sustaining plant growth. At altitudes up to the snow line, except where it is too dry, or where fire frequency is too high, or where the environment has been altered by natural disturbance or human activity.

Remarkably nature has gifted trees with the ability to survive in extreme weather conditions – from sub zero temperatures to dry scorching deserts. Trees grow in polar regions in Siberia, Alaska and Canada,… Read more “Trees grow almost anywhere – take the Joshua tree”

Microscope view of stomata... open and close absorbing carbon dioxide and releasing oxygen and water vapour.

The biological miracle of trees

February 17, 2016 / John Halkett

Trees have been described as the biological miracle at the very core of human evolution, for not only do they provide the essential ingredients that have given rise to the creation of life, they hold the key to the continuity of humanity. At the most basic level, it is the leaves in the green tree canopies where the truly magic story of nature is to be found.

Within the green, thin and vein-covered fabric of leaves something truly miraculous happens that provides the spark of life. It is the intrigue of how leaves, in a process called photosynthesis, are able to turn carbon dioxide from the sky into giant… Read more “The biological miracle of trees”