Researching the origin and meaning of the Christmas Tree, there is much information to get a better understanding of this traditional symbol.

"Many legends exist about the origin of the Christmas tree. One is the story of Saint Boniface, an English monk who organized the Christian Church in France and Germany. One day, as he traveled about, he came upon a group of pagans gathered around a great oak tree about to sacrifice a child to the god Thor. To stop the sacrifice and save the child's life Boniface felled the tree with one mighty blow of his fist. In its place grew a small fir tree. The saint told the pagan worshipers that the tiny fir was the Tree of Life and stood the eternal life of Christ.

Another legend holds that Martin Luther, a founder of the Protestant faith, was walking through the forest one Christmas Eve. As he walked he was awed by the beauty of millions of stars glimmering through the branches of the evergreen trees. So taken was he by this beautiful sight that he cut a small tree and took it home to his family. To recreate that same starlight beauty he saw in the wood, he placed candles on all its branches.

Yet another legend tells of a poor woodsman who long ago met a lost and hungry child on Christmas Eve. Though very poor himself, the woodsman gave the child food and shelter for the night. The woodsman woke the next morning to find a beautiful glittering tree outside his door. The hungry child was really the Christ Child in disguise. He created the tree to reward the good man for his charity.

Others feel the origin of the Christmas tree may be the "Paradise Play." In medieval times most people could not read and plays were used to teach the lessons of the bible all over Europe. The Paradise Play, which showed the creation of man and the fall of Adam and Eve from the Garden of Eden was performed every year on December 24th. The play was performed in winter creating a slight problem. An apple tree was needed but apple trees do not bare fruit in winter so a substitution was made. Evergreens were hung with apples and used instead."
http://www.theholidayspot.com/christmas/history/xmas_tree.htm

"Long before the advent of Christianity, plants and trees that remained green all year had a special meaning for people in the winter. Just as people today decorate their homes during the festive season with pine, spruce, and fir trees, ancient peoples hung evergreen boughs over their doors and windows. In many countries it was believed that evergreens would keep away witches, ghosts, evil spirits, and illness.

In the Northern hemisphere, the shortest day and longest night of the year falls on December 21 or December 22 and is called the winter solstice. Many ancient people believed that the sun was a god and that winter came every year because the sun god had become sick and weak. They celebrated the solstice because it meant that at last the sun god would begin to get well. Evergreen boughs reminded them of all the green plants that would grow again when the sun god was strong and summer would return.

The ancient Egyptians worshipped a god called Ra, who had the head of a hawk and wore the sun as a blazing disk in his crown. At the solstice, when Ra began to recover from the illness, the Egyptians filled their homes with green palm rushes which symbolized for them the triumph of life over death."

"In Northern Europe the mysterious Druids, the priests of the ancient Celts, also decorated their temples with evergreen boughs as a symbol of everlasting life."
http://www.historychannel.com/exhibits/holidays/christmas/trees.html

"Using the clippings of evergreen shrubs from the landscape to decorate houses, a common practice during the December celebrations of Saturnalia, was strictly forbidden by the Church. The associations between decorating with evergreen shrubs and paganism were just too strong. Already in the early third century Tertullian had complained that too many fellow-Christians were falling into the Saturnalian rut by adorning their houses with lamps and with wreathes of laurel as Christmas decorations (Tertullian, "On Idolatry," XV).

But the controversy over Christmas tree decorating and using clippings of evergreen shrubs as Christmas decorations is not relegated to that remote epoch in history. In the sixteenth century John Calvin objected to observing the Christian calendar -- which includes Christmas and Easter -- because he felt such celebrations promoted irreligious frivolity. It was in this same century that Germany, by contrast, was establishing Christmas tree decorating as we know it today, launching the modern history of the Christmas tree. But in England the Puritans, influenced by Calvin, forbade the observance of Christmas (see "The Christian Calendar: A Complete Guide to the Seasons of the Christian Year," Cowie and Gummer). And it wasn't until the mid-nineteenth century, at the instigation of Prince Albert, that Christmas tree decorating achieved its present status in England."
http://landscaping.about.com/cs/winterlandscaping1/a/christmas_trees.htm

"The tradition of having an evergreen tree become a symbol of Christmas goes back past recorded written history."
http://www.merry-christmas.com/stories/histortree.htm

http://www.infoplease.com/spot/christmas2.html

http://mymerrychristmas.com/2005/christmasbeforechrist.shtml

There is much more information to be gathered regarding this practice.