Trees in Trouble

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Pesky Pines

Since being introduced from North America, Pine trees have changed the face of the Australian landscape. While Pine plantations have certainly boosted our economy, there are untold costs for councils and land care groups left with the task of removing renegade pine trees from protected bushland reserves.

Pine trees are classified as environmental weeds or significant environmental weeds across the country due to their ability to spread, affecting the biodiversity of sensitive areas.

The history of Pines in Australia Pinus radiata (Radiata Pine) was grown in the Sydney Botanic Gardens as early as 1857. It is thought these trees were brought here by miners coming from the Californian gold rushes to the Australian goldfields. They grow naturally on a narrow stretch of coast in southern California and on two small islands off Mexico.

A similar widespread species is Pinus elliottii (Slash Pine); it grows in areas from South Carolina to Florida and west to Louisiana.

Both species, along with other introduced Pines, have become naturalised in Australia, particular near forestry plantations.

The Negatives

Pines have winged seeds which has aided their dispersal into bushland where they compete with native species. Growing up to 50 metres tall, they block out sunlight and smother the earth with fungi resulting from fallen leaf, branches and cones. Viable seeds may remain in the cones for several years and are often shed abundantly after fire, which kills the parent tree.

In practical terms it may never be possible to eliminate this dispersal while the seed source remains. Genetic modification to produce sterile Pines which put more energy into wood production than reproduction appears to be the only solution to invading Pines; however this scientific achievement is a long way off.

Arborist Ken Folkes has been around Pines most of his life and is of the opinion that if the natural environment is intact, Pine wildling invasion is very minimal due to the allopathic effects of the native biosphere.

“Like all flora and fauna, including humans, we are all opportunistic and will invade a given area at the first chance,” said Ken.

“I’ve worked in a Pine plantation and also in bush regeneration removing Pine wildlings, and am aware of the allopathic effect on other plant species and other environmental nasties they cause. However, Pines are an important commercial timber and are here to stay, although plantation management practices are much more sustainable and environmentally friendly than years gone.

The Positives

According to latest updates in Australian plantation statistics 2018, the total area of softwood plantations is approximately 1,036,900 hectares. Most of the timber harvested is used for structural timber for houses. The industry produces enough timber each year to build around 14 percent of houses built in Australia each year.

“Arborist Ken Folkes has been around Pines most of his life and is of the opinion that if the natural environment is intact, Pine wildling invasion is very minimal.”

The Forestry Corporation of New South Wales manages state forests on behalf of the NSW Government. It has over 230,000 hectares of Pine plantations, consisting of about 90 percent Radiata. The bulk of the resource underpinning today’s industry was established from the late 1950s to mid 1970s. The first commercial Radiata pine plantation in NSW was established at Tuncurry on the mid-north coast in 1914.

In 1920, Pinus elliottii was introduced into Queensland, and in 1970 it was crossed with Caribbean Pine to form the hybrid Southern Pine. The hybrid combines the best attributes of both species to yield higher proportions of structural timber grade than Radiata. It is grown by HQ Plantations in coastal regions from northern New South Wales to Rockhampton.

Pests and Diseases of Pines

Pinus species are restricted strongly to the latitude where they occur naturally. Southern Pines originate from latitudes equivalent to that of Queensland, and Radiata from latitudes the same as southern New South Wales. If grown in Queensland, Radiata is highly susceptible to attack from Diplodia and does not perform well.

There are a number of potential pests of Southern and Radiata Pines that are not known to exist in Australia yet but are incorporated into Australian biosecurity programs.

Sirex wasp is a potential pest, which currently only extends from the southern states (in Radiata) to just over the Queensland border; it is not yet established in the main Southern Pine estate in Queensland.

When plantations become stressed from drought or fire they become susceptible to attack from other pests such as the Five-spined bark beetle (Ips grandicollis) and Californian Pine aphid (Essigella californica).

The recent Giant Pine Scale incursion into certain urban areas in Victoria and South Australia is another potential pest that could impact Southern Pines if it spreads north. Fortunately, this pest is yet to be detected in any commercial Pine plantations in Australia.

Pest and Disease Workshop

Janet McDonald has been working with the Forest Health Surveillance (FHS) team since 1998 conducting pest and disease surveys in forestry plantations throughout Queensland. On March 6, 2019 Janet will conduct a Pest and Disease Workshop at QAA Headquarters in Redland City to help arborists to recognise and identify problems in all kinds of trees. (Visit qaa.net.au to register.)

How to Identify Pines

Radiata Pine (Pinus radiata) has relatively large asymmetrical cones (7-17 cm long) that are borne on short curved stalks. Its leaves are relatively short (8-15 cm long) and usually borne in groups of three (rarely in twos). Radiata bark is dark brown in colour with deep ridges.

Slash Pine (Pinus elliottii) has relatively large symmetrical cones (7-20 cm long) that are borne on short stalks. Its leaves are relatively long (15-30 cm long) and borne in groups of two or three (usually in twos). The bark is grey to rusty brown and sheds in flat discs, and the cones of Slash pines have small prickles on the tips of their woody scales

March 15, 2019 / by / in
The White Cypress

The White Cypress is sought after by many, for different reasons. There is no doubt, the future of this classic beauty must be carefully considered.

Often referred to as a Pine Tree, this look-alike belongs to the Cupressaceae family. Its botanical name Callitris glaucophylla originates from Greek words – Glaucos meaning silvery or bluish-green and phyllon, referring to leaf. Crush a leaf and it will expel a fresh pine scent.

On sandy soils and well-drained slopes, where it prefers to grow, this narrow upright tree can reach 20 metres. On skeletal soils, it is often supplanted by Black Cypress (C. endlicheri) – distinguishable by its greener foliage and egg-shaped cones; the cones of White Cypress are globular shaped.

Male and female cones are found on the same tree, and during winter, the male cones shed masses of pollen relying on wind to transfer their pollen to female cones. Later in the season, the cones split open to shed their small winged seeds. Regeneration comes from seedlings buried in the ground rather than buds.

Unlike many Australian species, the White Cypress is not resistant to fire and excessive burning makes regeneration near impossible. Fire suppresses seed production, which leaves damaged trees vulnerable to predatory wasp attacks.

Sheep and cattle (and rabbits) also suppress the growth and survival of seedlings when broad scale clearing occurs. Earlier this year the Queensland Government banned broad scale clearing of remnant vegetation and graziers are now required to apply for approvals to clear any vegetation for feeding livestock.

Alternatively, some land managers are now replanting White Cypress with the goal of sustainably harvesting its highly prized honey coloured timber. So-called Cypress Pine is well-known for its resistance to decay in the ground and attacks by white ants, termites and Lyctus borers; so doesn’t require treatment and is safer for commercial use. It has very small shrinkage on seasoning and is widely used in the building industry.

White Cypress is deemed as a most important native species by commercial forestry and there has been much debate about its harvesting from natural stands. In 2013, the NSW Premier asked the Natural Resources Commission (NRC) to investigate active and adaptive management of Cypress forests in the State Conservation Areas of the Pilliga, namely Brigalow and Nandewar.

Research carried out by the Commission suggested that ecological thinning of dense Cypress forests would actually benefit biodiversity, if applied at patch scales rather than broad landscape scales. The report recommended that additional interventions such as targeting grazing and prescribed burning be available as options where appropriate.

Timber managers, running out of areas to log, were hopeful the report would secure the industry’s future. However, the Government did not accept the Commission’s recommendations.

Other Uses

The White Cypress has a strong place in Aboriginal culture; its timber once was used to make woomeras, canoe poles and spear shafts, while its resin provided waterproof adhesive. The wood has a characteristic resinous odour and a slightly greasy feel and it is the oil distilled from the wood that is now sought by emerging companies. It has an incredible soothing and grounding property and is used widely as a fixative in perfumery and, more recently, in anti-anxiety aromatic medicine.

White Cypress and Wildlife

Unlike exotic pines, White Cypress are important habitat for birds and mammals alike. The thick fibrous bark supports an abundant supply of grubs bringing insect-eating birds to forage. Grey-crowned Babbler and Apostle Birds love to forage in foliage and on ground nearby. Parrots and cockatoos feed on seed-bearing cones while dead trees provide hollows for insectivorous bats and reptiles. Pollen yielded in useful quantities benefits bees.

Nest entrances of the Funnel Ant (Aphaenogaster Barbigula) are a common ground feature over extensive areas of sandy soils dominated by Cypress in Eastern Australia. The deep cavities they excavate play an important role in altering both the physical properties of the soil and its hydrology.

An Underestimated Garden Specimen

Land care groups encourage residents to plant native Cypress instead of ubiquitous exotic conifers. Toowoomba Regional Council, with the help of volunteers, grows native Cypress species at the Crows Nest Community Nursery. Volunteer Patricia Gardner has an amazing blog showing many of the local native plants.

Supervisor Nursery Operations Lisa Churchward said people could get confused when buying Cypress as it is a common name given to a lot of nursery plants including both exotic and native.

“Being able to tell the difference comes down to education and the use of botanic names in place of common,” Ms Churchward said.

“In a cultivated situation native Cypress are a great ornamental tree reaching a height of 18 metres. When maintaining trees it is best to make sure they are maintained to a single trunk as multi branching down low can cause the tree to split.”

Callitris Mistletoe (Muellerina bidwilli)

This rarely observed mistletoe specialises on native Cypress (Callitris species) and is mostly western in its distribution. As the Brigalow Belt encompasses large swathes of Callitris, for example the Pilliga Scrub in centralwestern New South Wales, mistletoe is commonly found. It is absent from Stradbroke Island but does occur on both Moreton and Fraser Islands.

December 10, 2018 / by / in