<P> Using wood pulp to make paper is a fairly recent innovation, that was almost concurrent to the invention of automatic papermaking machines, both together resulting in paper and cardboard becoming an inexpensive commodity in modern times . Although the first use of paper made from wood pulp dates from 1800, as seen in some pages of a book published by Matthias Koops that year in London, large - scale wood paper production began with the development of mechanical pulping in Germany by Friedrich Gottlob Keller in the 1840s, and by the Canadian inventor Charles Fenerty in Nova Scotia, Chemical processes quickly followed, first with J. Roth's use of sulfurous acid to treat wood, then by Benjamin Tilghman's U.S. patent on the use of calcium bisulfite, Ca (HSO), to pulp wood in 1867 . Almost a decade later, the first commercial sulfite pulp mill was built, in Sweden . It used magnesium as the counter ion and was based on work by Carl Daniel Ekman . By 1900, sulfite pulping had become the dominant means of producing wood pulp, surpassing mechanical pulping methods . The competing chemical pulping process, the sulfate, or kraft, process, was developed by Carl F. Dahl in 1879; the first kraft mill started, in Sweden, in 1890 . The invention of the recovery boiler, by G.H. Tomlinson in the early 1930s, allowed kraft mills to recycle almost all of their pulping chemicals . This, along with the ability of the kraft process to accept a wider variety of types of wood and to produce stronger fibres, made the kraft process the dominant pulping process, starting in the 1940s . </P> <P> Global production of wood pulp in 2006 was 175 million tons (160 million tonnes). In the previous year, 63 million tons (57 million tonnes) of market pulp (not made into paper in the same facility) was sold, with Canada being the largest source at 21 percent of the total, followed by the United States at 16 percent . The wood fiber sources required for pulping are "45% sawmill residue, 21% logs and chips, and 34% recycled paper" (Canada, 2014). Chemical pulp made up 93 percent of market pulp . </P> <P> The timber resources used to make wood pulp are referred to as pulpwood . Wood pulp comes from softwood trees such as spruce, pine, fir, larch and hemlock, and hardwoods such as eucalyptus, aspen and birch . </P> <P> A pulp mill is a manufacturing facility that converts wood chips or other plant fibre source into a thick fiberboard which can be shipped to a paper mill for further processing . Pulp can be manufactured using mechanical, semi-chemical or fully chemical methods (kraft and sulfite processes). The finished product may be either bleached or non-bleached, depending on the customer requirements . </P>

Where do the plant fibres that are used to make paper come from