As regards growth in diameter the case is somewhat different. In all woody plants it takes place throughout the period of vegetation, from the time the tree comes into leaf until the leaves fall in the autumn, and the extent is influenced by the weather of the current year.
Trees grown for their wood are cultivated in forests. Unlike other raw materials where the supplies are exhausted after a time, if felling is wisely planned, the supply of wood in a forest remains constant and the felled wood is replaced by new wood in the form of new growth.
In the mild climate of central and western Europe, the annual increment per hectare, depending on the site, type of soil and prevailing species, averages from three to ten cubic metres of wood that can be cut without decreasing the supply and production of further wood. With systematic care and fertilization this increment can be increased even further, as is shown by the plantations of cultivated hybrid poplars with an annual increment of fifteen to twenty- live cubic metres of merchantable wood.
The aspen, goat willow, birch and mountain ash may attain 100-150 years. Twice that age, from 200 to 300 years, is reached by the eastern cottonwood, hornbeam, alder, pine and larch; about 500 years by the beech and sycamore; and 700 years by the spruce and fir.
The oldest trees in central and western Europe are the lime, yew and oak, which may live for more than a thousand years. An even greater number. of years is attained in the Mediterranean region by the oriental plane, chestnut and the cedar of Lebanon - as many as two thousand; and on the American continent there are trees that are much older. Up to 2500 annual rings were counted on the stump of a redwood and some giant sequoias are 3500 to 3800 years old.
In the furniture industry, it is mainly the wood of broad-leaved trees such as oak, elm, walnut, ash, beech, cherry arid certain tropical exotics that is used to make the finer, more delicate pieces. In recent decades, only thin layers, called veneers, of these costly woods are being used; they are main structure made of soft wood, thus making the final product not only lighter but also less expensive. - 16035
Trees grown for their wood are cultivated in forests. Unlike other raw materials where the supplies are exhausted after a time, if felling is wisely planned, the supply of wood in a forest remains constant and the felled wood is replaced by new wood in the form of new growth.
In the mild climate of central and western Europe, the annual increment per hectare, depending on the site, type of soil and prevailing species, averages from three to ten cubic metres of wood that can be cut without decreasing the supply and production of further wood. With systematic care and fertilization this increment can be increased even further, as is shown by the plantations of cultivated hybrid poplars with an annual increment of fifteen to twenty- live cubic metres of merchantable wood.
The aspen, goat willow, birch and mountain ash may attain 100-150 years. Twice that age, from 200 to 300 years, is reached by the eastern cottonwood, hornbeam, alder, pine and larch; about 500 years by the beech and sycamore; and 700 years by the spruce and fir.
The oldest trees in central and western Europe are the lime, yew and oak, which may live for more than a thousand years. An even greater number. of years is attained in the Mediterranean region by the oriental plane, chestnut and the cedar of Lebanon - as many as two thousand; and on the American continent there are trees that are much older. Up to 2500 annual rings were counted on the stump of a redwood and some giant sequoias are 3500 to 3800 years old.
In the furniture industry, it is mainly the wood of broad-leaved trees such as oak, elm, walnut, ash, beech, cherry arid certain tropical exotics that is used to make the finer, more delicate pieces. In recent decades, only thin layers, called veneers, of these costly woods are being used; they are main structure made of soft wood, thus making the final product not only lighter but also less expensive. - 16035
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Garden planning for the urban front garden often has to provide parking space. While it is difficult totally to hide parked cars, sensible planting can offer partial screening.
