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   To the mathematically challenged, the formula might as well be written in a foreign language, but Paul Doruska, associate professor of biometrics/inventory, knows exactly what it means – a better way for landowners to know the value of their hardwood timber.

   Doruska is a research scientist in the Arkansas Forest Resources Center and a member of the faculty in the school of Forest Resources at the University of Arkansas at Monticello. Doruska and fellow research professor of wood science David Patterson have been looking for better and more accurate methods of predicting the weight of hardwood timber as well as converting from volume estimates to weight.

   Doruska previously developed a mathematical formula to more accurately predict pine weight, a formula that has been adopted by many in the timber industry. Now he has developed a better way to estimate hardwood weight. Doruska and Patterson began working on the problem to help timber sellers and buyers speak the same language.

   "In the past, land owners kept track of their timber in terms of volume while mills were buying in tons," Doruska explained. "It was important to get everyone on the same page."

   Doruska and Patterson went to several locations around the state to take hardwood measurements, including the Ozark National Forest and the Felsenthal National Wildlife Refuge. Equations using the same tree attributes, or variables, but with different numeric multipliers, or coefficients, were developed for seven different oak trees in south Arkansas and three in the northern part of the state as well as formulas for two varieties of hickory and one for sweetgum.

   Patterson's part of the project involved developing measures of the bulk density (pounds per cubic foot) of hardwoods since a typical hardwood tree is denser and heavier than a pine tree.

   "When timber comes to the mill, the buyer needs to know how much he's going to get in lumber, sawdust and chips," Patterson said. "We're trying to give him an accurate measurement."

   Developing conversion formulas for a typical pine tree required just four measurements of the tree’s diameter. Measurements for hardwood trees proved to be a more difficult challenge.

   "Look at a pine tree, then look at an oak tree," Doruska said. "They're very different. Pines have a fairly straight stem. Hardwoods don't."

   To make a formula work for hardwoods, Doruska and Patterson took 15 to 20 diameter measurements per tree. Adaptations were also made to compensate for the heavier nature of hardwoods compared to pines.

Photo courtesy of Media Servies

Easy - Doruska works with loggers to weigh oak timber.

   Doruska and Patterson wrote the initial grant proposal for a pine study in 2001, but soon realized they were not serving timber owners in northern Arkansas where hardwood forests are predominant, nor the hardwood timber owners in southern Arkansas.

   "There is a strong market for hardwood timber in Arkansas, and contrary to what some would have you believe, we are not cutting all the hardwoods and replacing them with pine," Doruska said.

   According to a recent timber inventory from the Arkansas Forestry Association, Arkansas has 18.5 million acres of timber, including 7 million acres of upland hardwood, 3 million acres of bottomland hardwood, 3 million acres of mixed oak and pine, and 5.5 million acres of pine.

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