Wide-ringed wood is often called "second-growth", because the growth of the young timber in open stands after the old trees have been removed is more rapid than in trees in a closed forest, and in the manufacture of articles where <answer>strength</answer> is an important consideration such "second-growth" hardwood material is preferred. This is particularly the case in the choice of hickory for handles and spokes. Here not only <answer>strength</answer>, but toughness and resilience are important. The results of a series of tests on hickory by the U.S. Forest Service show that:
What property is important to manufacturers who use "second-growth" hardwood?
strength