![]() ![]() As a rough rule, the diameter limit is generally set with the objective that every tree harvested should pay its way out of the woods in other words, the value of the wood it contains should exceed the costs of harvesting it. The target dbh for a given logging job is dependent on the species, the markets, and harvesting costs. All trees below a chosen dbh, usually in the range of 10 to 14 inches dbh that haven’t been cut, broken off, nor uprooted during the harvesting operation are left for future growth. In forestry terms, tree diameter is measured at breast height, defined as 4 ½ feet above ground level, leading to the term, diameter at breast height (dbh). In its simplest form, diameter-limit cutting is the practice of harvesting all of the trees on a parcel that are larger than a certain diameter. I had to tell him the hard truth: the real reason for the decline in tree – and hence log – quality with each succeeding harvest was that he was practicing diameter-limit cutting. What was going on, he asked me? Some disease or insect? Weird weather? He was proud of the quality of his harvesting and thought he was practicing good forestry he didn’t understand why log quality was declining with each harvest. The second time around, the logs had been smaller and generally of lower quality, while the logs from the current harvest were so poor that the job was far less profitable than he had expected. The first harvest, some 30 years before, had yielded a good share of veneer-quality hardwood and lots of nice sawlogs. This was the third time he had harvested this particular piece, and he had noticed each time that the quality of the logs he was getting had markedly decreased from the previous harvest. Several years ago, a logger showed me the harvesting he was doing on a piece of his family’s property. The larger ones are growing more vigorously and can increase in value if left to grow. These trees got their start at the same time. ![]()
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