Last week's storm brought strong winds that removed shingles and roofs and mangled trampolines. It also took trees apart and knocked them down. A drive around areas where the storm wreaked the most havoc revealed branches strewn about and skeletal remains of trees. Interestingly, not all the trees broke and/or toppled. Some seemed to be sturdier than others.

Why the difference?

Variety makes a big difference. Many of the trees that suffered severe damage came from just a few varieties. Some trees are more brittle than others and some are shallow-rooted and more likely to be upended in a storm. Others simply bend and flex more easily and do not suffer as much in a wind storm. In Stansbury Park, the Russian olives and willows fared poorly, although there were exceptions among other trees. In Erda, the Siberian elms were among those that dropped branches helter-skelter.

Although the poplars are tall and therefore seemingly most susceptible to the wind, they did not come down. They did, however lose branches freely -- perhaps that is to the trees' advantage -- it is better to lose a few branches in favor of the whole tree. Poplars are notorious for losing branches easily.

In general, the trees that grow the most quickly inherently have the weakest wood. Trees that grow quickly are never as structurally sound as tree species that grow slower.

Although the serious wind last week caused a great deal of tree damage, other weather conditions are also capable of bringing down branches, the most notable being snow. Taking proper care of trees and helping create a strong structure can mean the difference between a tree that fails and a tree that withstands the ravages of high winds and the weight of snow.

The angle of branching is one important consideration. Branches that extend from the trunk at about a 45-degree angle are the strongest. When they are aligned in too upright a position, the crotch angle becomes weak, particularly as the tree grows older. As a tree grows and matures, the branches and the trunk both expand. When branches are angled too close the main trunk, the bark that is at the crotch becomes "included" -- the branch and trunk grow around it rather than expanding properly. This creates a weakness there that is liable to break easily.

Some trees inherently develop weak crotches. One clear example is the Bradford pear tree. The branches all come out of the trunk at nearly the same place and tend to grow rather upright. Any tree can develop that tendency. Too many branches at the same level are very likely to break under stress. It is difficult to correct this problem, and better to choose a variety that does not have this characteristic.

Sometimes trees form double crowns -- two trunks that split apart and extend upward with both branches becoming equal leaders. You may see this in pines as well as in deciduous trees. Such trees have an inherent tendency to split in wind and heavy snow. In these cases, cut away one of the upward trunks and allow the other to be the dominant leader, preferably when the condition first develops.

Deep roots go a long way toward keeping trees solid. Unlike a popular misconception, trees do not develop tap roots after they are transplanted. Roots tend to spread wide, about twice the width of the tree top. Some tree varieties, like willows, naturally develop shallow roots. If you have grown one, the roots that have sneaked above the soil line may show the battle scars of its encounters with your lawnmower.

If water is readily available at the surface of the soil, tree roots tend to grow there. Encourage deeper rooting by following good water practices. Trees should be watered deeply and thoroughly, but not too often. When a small tree is first planted, it will require frequent water for a short time while the roots grow into the surrounding soil. Gradually taper back on frequency and water deeply. As the soil surface dries out, the plant will develop roots that extend downward toward the water deeper in the soil. Deeper roots will anchor the tree more securely so that they can withstand winds.

Trees need to develop thick, sturdy trunks to hold up the tops and stand firm in storms. Small trees are often staked to hold them against wind damage. This practice requires a certain amount of restraint. Studies show that trees that are not staked tend to develop stronger trunks in response to the stresses of winds. On the other hand, if the stresses are too great, the tree will blow over or break before it gets a chance to develop trunk strength.

If you decide to stake your trees, it is best to use just one stake. Put the support high on the tree and keep it loose so the tree can move to some extent in the winds.

Sometimes the weaknesses in trees are man-made. When you plant a tree, remove all wires, strings and similar items from the branches and trunk. After a stake has served its purpose, remove the stake and the wires, hoses and other supports that anchor the tree to it. Otherwise the tree tends to grow over them and develop a weak spot where this takes place.

If you decide to pull a tree back together, branches may reattach and splits may grow over. For obvious reasons, never put wires, ropes or strings around a tree to hold it together. Instead, put a bolt through the tree with a washer and nut on each end to keep it together. It can be left in place until the tree grows over it. Remember the bolt is there so when it comes time to take down the tree you won't hit it with a saw.

Take good care of trees so that they will look good and grow well for a very long time.