POPLARS (Populus spp)

Family: SALICACEAE

Poplars generally use large amounts of water, will grow adjacent to waterlogged soil and have root systems that have been known to reach out as far as 50 m laterally in search of moisture and nutrient. For this reason, they are extremely good trees for, erosion and for salinity control, but should not be planted close to gardens, septic systems and orchards. Some poplars will tolerate prolonged periods of flooding. They are fast growing, yield a soft, light timber, and provide useful fodder for stock. They grow best in an open, unshaded situation.

The foliage of poplars is extremely nutritious as a stockfeed. Not only will stock eat all the foliage they can reach, including any suckers shooting up from the parent tree roots, but also eat the leaves that fall in autumn. Poplar foliage is superior nutritionally to lucerne.

Composition of Lucerne, Fodder Grasses and Poplar Leaves..

Expressed as a percentage (Food and Agriculture Organisation)

"A Hunter River farm in New South Wales, 40 hectares of river flats, was progressively planted to wide spaced poplars for timber production, with the branch and leaf material from the pruning of the trees being fed to beef cattle. At the outset of the plantings, it was hoped to be able to hold cattle numbers constant, despite the trees, because of these prunings. However, in reality, it was found that numbers could be increased by 20%. There was more summer grass due to the humidifying and sheltering effect of the trees and more winter grass because the trees, even without their leaves, kept the site warmer. The poplars reached timber harvest size in just 15 years. The overall increase in productivity was startling." (Ref. Thamo. A. "Fodder Trees" from "Trees for Farms").

In Maine, USA, poplar wood is being chipped and steamed to provide roughage feed for sheep and cattle at US $3 5/tonne (1981 prices). "As a maintenance ration, the steamed poplar can satisfy about 65% of a dry sheep's requirements". (Ref. White. T. "Poplars and Pampas" from Permaculture Journal, issue 7, March 1981).

In Dungong in N.S.W and at Darville in South Africa sewerage effluent water is used to irrigate poplar plantations. The poplars are sold to match companies and provide a lucrative return to the two municipalities.

Poplar wood is soft, suitable for wood pulp and paper, although it is also used for a wide variety of other purposes. First quality wood is used in furniture manufacture, for the interiors of cupboards, sideboards and for shelving. Poplar wood can also be used in construction work, for framework and roofing timbers, providing it is not subject to too great mechanical stresses and is protected from the elements. Other uses of poplar wood include matches, fruit boxes, plywood, fibreboard, chipboard, woodwool, packing cases, flooring, kitchen utensils, wooden toys, drawing boards and tables and rough boarding. Poplar wood does have a tendency to defects due either to insect or fungal attack, anatomical structure, or internal growth stresses, which lessens its commercial value.

Poplars can be propagated from cuttings, like willows. They can even be established from cuttings 10 m high, provided they can access water. Cuttings taken from young trees strike root more easily than cuttings taken from older trees, and the terminal shoots are generally not suitable. Experiments in propagating P. deltoides in the USA have shown marked seasonal variations, autumn being the most successful time, winter also being satisfactory. Phosphorus has also been shown to have a good effect on root development.

Willows and poplars can be planted around the edge of salt scalds, and trials to establish trees on soil mounds in the scalds could be rewarding. The suckering, salt tolerant varieties of poplars may even 'colonize' such scalds.

Being deciduous trees, willows and poplars are not effective windbreak species for winter winds but can be planted to shelter from hot summer winds. Being deciduous, however, allows a range of understorey, including the perennial bana grass, elephant grass, pampas grass and bamboo, to make growth over the winter months.

Good companions to the willows and poplars are any of the useful nitrogen fixing legumes, tolerant of the same conditions, (eg Acacia saligna for fodder and Acacia melanoxilon for first grade furniture timber).