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Trees form vital part of land's ecosystem

"You don't know what you've got ‘til it's gone."

It seems that it's human nature to take for granted that which is always here. That's never more true than with trees and the soil they grow in. But what happens to our lives when they dwindle... or even vanish?

I recently read a review of a book titled "Collapse" by Jared Diamond. He researches and explains the mysterious disappearance of several civilizations. There are two in particular that rang a bell with me, due to my interest in land conservation.

Whatever happened to the Norse settlements in Greenland and the inhabitants of Easter island? Mr. Diamond's research is fascinating, particularly for those of us who are concerned with gardening and landscaping!

Firstly, Greenland. About one thousand years ago, a group of Vikings landed in what's now known as Greenland and set up two settlements on the grassy slopes that were protected from the Arctic ocean. Before long, they had built many houses, parish churches and even a cathedral, using wood from the trees they cut down. They had brought cattle and other livestock from their homeland and the cows, sheep and goats grazed on the grass.

However, by 1408 the settlements were deserted. All the inhabitants who had not returned to Northern Europe had starved to death. The reason? They had chopped down entire forests for fuel or building materials, and new trees couldn't grow fast enough to replace them. The shallow layers of topsoil were lacking in soil constituents such as organic humus and clay, necessary to hold on to moisture and keep the soil resilient to wind erosion.

Mr. Diamond adds: "With the trees and shrubs gone, livestock, especially sheep and goats, graze down the grass, which regenerates only slowly in Greenland's climate. Once the grass cover is broken and the soil is exposed, soil is carried away ... to the point where the topsoil can be removed for a distance of miles from an entire valley."

But this isn't a problem unique to the "frozen north."

At one time, according to the author, Easter Island was home to a thriving culture that produced the famous stone statues that we are all familiar with. At one time, the island supported dozens of different species of trees, which in turn protected a fertile ecosystem that supported a population of up to thirty thousand. But now, the island is just a barren rock.

Like the Norse in Greenland, the Easter Islanders cut down all the trees until there were none left. And with the trees gone, there was nothing to protect the grass and the soil which was rapidly eroded. Mr. Diamond writes: "I have often asked myself, ‘What did the Easter Islander who cut down the last palm tree say while he was doing it?'"

Of course, you and I don't live by a frozen fjord lashed by the Arctic ocean or on a remote island in the Pacific. However, I believe the two situations I've described should resonate in some way with all of us.

Trees are so much more than pleasant decorations or handy poles between which we can hang a hammock. Healthy trees form a vital part of our landscape, nurturing the grass and the layers of soil beneath them. Additionally, trees produce oxygen, provide shade in the summer and a buffer against cold winter weather.

With spring just around the corner, I encourage you to think seriously about planting some trees in your own corner of the world. You will enjoy their beauty as they grow and spread year after year. And you'll have the satisfaction of knowing that you're providing your own contribution to ensuring that a vibrant ecosystem will be around for your children and grandchildren.

If you need some specific advice about planting trees in your location, simply e-mail me a few details about where you live, the type of soil and terrain and the effect you wish to achieve. I will send you a personal reply, and might include your question in a future column.

The Plant Man is here to help. Send your questions about trees, shrubs and landscaping to [email protected] and for resources and additional information, or to subscribe to Steve's free e-mailed newsletter, visit www.landsteward.org