Last November (2009), the US Fish and Wildlife Service raided the Nashville offices of Gibson Guitars and hauled off computers, guitars and stocks of wood as part of an investigation of the guitar company for allegedly importing illegal rosewood from Madagascar. Rosewood (genus Dalbergia) is the favored material for the back and sides of acoustic guitars: it's dense, with a beautiful russet color, whorly grain and a smoky fragrance you can smell each time you open the guitar case, even on a guitar several years old. As the hard surface reflecting the sound waves inside the guitar's box, it affords a rich yet punchy sound with long sustain. Guitarists love rosewood.
I've got two guitars made with Brazilian and one with Indian rosewood; I'd even bet that the nylon-string guitar that Sting, founder of the Rainforest Foundation, plays on "Fragile" is made of Brazilian rosewood. The Gibson case remains under investigation, and Gibson has pledged cooperation with the authorities, while maintaining that it is not in violation of the Lacey Act, the US law prohibiting import of endangered species. In fact, Gibson may have simply been caught up in the un-Raval-ing of Madagascar's democracy: protests and a coup in late March 2009 drove out the democratically elected president, Mark Ravalomanana, who had held power since 2002. In his years in office, Ravalomanana had protected lands in a system of national parks, promoted sustainable farming, and with international aid pursued other ecologically friendly projects. Gibson has been publicly active in promoting sustainable and legal trade in woods—its Chairman and CEO sat on the board of Rainforest Alliance; the company claims its Madagascar woods all have clear chain-of-custody documentation. But Madagascar rosewood has become suspect on international markets since the coup. Lawlessness and the curtailment due to sanctions of international aid for environmental projects have opened even protected forests to slash-and-burn farmers and to an armed "timber mafia" who harvest the rosewood and ebony for export. The new president, Andry Rajoelina, legalized rosewood and ebony exports and his government benefits from an export tax on raw woods, justifying this policy by saying the trees were felled by cyclones. (More on this from National Geographic here.) Madagascar suffers further economic pressure due to the collapse of world prices for vanilla bean, another of the island's main exports. This arises in part from international aid efforts to expand vanilla production in tropical countries (which have the unintended effect of depressing vanilla prices world-wide), and from increased synthetic vanilla production in China. And China, too, now imports most of Madagascar's rosewood, producing flooring and furniture for export and domestic use. 
But lutiers the world over also pay top dollar for Malagasy rosewood ($5000 per cubic meter), and, in their own way, as do those who buy guitars made of this wood, further the deforestation of Madagascar and threaten the lemurs and other endangered species.
There have been similar cases in recent years involving Dalbergia nigra, aka Brazilian rosewood, aka jacaranda da bahia, aka palosanto de Rio, the most popular rosewood for guitars and other instruments and another species on the CITES (Convention on International Trade in Endangered Species of Wild Flora and Fauna) endangered list. In 2004, Spanish authorities seized 33 tons of Brazilian rosewood from Spanish warehouses. A thirty-member gang had been importing and reselling the wood to guitar makers in Cuenca, Grenada, the US, Germany, and Japan. In late 2007, in an operation that ranged from eastern Brazil to central Massachusetts, Brazilian police and the US Fish and Wildlife Service arrested 23 members of another gang, this one alleged to have smuggled 13 tons of rosewood into the US. It is the market for Brazilian rosewood guitars that supports this smuggling.
The international trade in tone-woods and the commercial webs that link Spain, the Americas, Africa and Asia go back a long time. Half a millennium ago, almost as soon as global maritime trade routes first opened up, the demand in European workshops for wood with exceptional acoustic and visual qualities pushed the tentacles of capitalism deep into the world's rainforests. In the sixteenth century, Iberian lutiers and violeros (vihuela makers) already employed a variety of exotic materials from around the old and new worlds in making instruments, including whalebone, Indian cane, rosewoods, Brazil wood (pernambuco or Caesalpinia echinata, now the best wood for violin bows), guaiac, sandalwood, ivory and ebony. Ebony was not only used for keyboards. The ordinances of the violeros guild (makers of vihuelas, an early guitar) in Toledo in 1617 specified that vihuela fingerboards be made only of this hard wood (as many chordophone fingerboards still are). From trees of the genus Diospyros and native to Africa, Madagascar and South Asia, ebony is dense enough to sink in water and was thus a favorite choice for parts of instruments which must endure much wear and tear, as well as for sides, back or ribs of instruments. One source (1550) mentions a Spanish vihuela with rib braces of fine ebony from the Island of Meroe, between the White and Blue Nile in Sudan.
Within a few decades of the European discovery of the Americas, and while Portuguese conquest and colonization of Brazil was still underway, the special qualities of Brazilian rainforest woods had already been identified and the wood was being cut and shipped to Europe. An inventory in 1564 of the instruments in the collection of Princess Juana of Austria mentions a vihuela with a "back of alternating Brasil [probably pernambuco] and white wood strips and the sides of ebony." The guitar maker Pablo de Herrara testified in his 1622 will that the Marqués de Alcañices owed him 800 reales for a guitar made of cocobolo wood—another Central American member of the rosewood family with an attractive grain and color pattern. He built another cocobolo guitar for the Count of Navalmoral worth 500 reales. (De Herrara chose his woods better than he chose his customers: upon his death the Queen herself still owed him 100 ducats for a guitar, though in his testament he generously offered to accept whatever she would pay). And we know that a maker named Phelipe Santiago Medina built a vihuela with rosewood ribs in the early 1700s.
If we define the guitar as a chordophone made with a sound box constructed from separate thin pieces for top, back and sides (as opposed to curved staves, like lutes, or carved out of a whole block of wood, like a gittern), then the first guitars (guitarra, vihuela) were invented around the same time as Iberians and other Europeans in their ships began to explore and exploit the wider world. Arguably, the fact that guitars require only thin pieces of wood made it more affordable to build them from extremely expensive materials brought by sail from halfway around the world, and the very design of the instrument thus reflects its era. 
From Princess Juana's vihuela, to the old Brazilian rosewood Martin D-28's played by Hank Williams, Elvis Presley and countless others, to the tens of thousands of instruments Gibson and other factories turn out today using new, cheaper woods to meet swelling demand, few guitars originate on a single continent. They have always been, and remain, global artifacts dependent on the marvelous materials of tropical forests.
