Dating Prehispanic Caribbean Wooden Sculptures: Wood Anatomist at Work

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Left to right: a) Pelican cohoba stand, Guaiacum sp., AD 978–1021 (modeled date for outer edge), Aboukir, Jamaica. Musée Barrois reliquary, Guaiacum sp., AD 1054–1181 (modeled dates), Dominican Republic/Haiti (?),Robsjohn-Gibbings duho, Guaiacum sp., AD 1451–1517. Courtesy of the National Gallery of Jamaica, Kingston, Musée Barrois, Bar-le-Duc, France, and modeled dates), the Division of Anthropology, American Museum of Natural History, New York, respectively.

Look at those wooden sculptures! Some FPL research could even be called exotic. Research Botanist Alex Wiedenhoeft  of the Engineering Properties of Wood, Wood based Materials and Structures research unit has worked with the Pre-Hispanic Caribbean Sculptural Arts in Wood project, which studied 66 wooden artifacts attributed to the pre-colonial Taíno, the indigenous peoples of the Caribbean’s Greater Antilles.

The Taíno inhabited Hispaniola (Haiti and the Dominican Republic), Puerto Rico, Jamaica, Cuba, the Bahamas, and the Turks and Caicos Islands at the time of first European contact in the late 15th century. The Taíno created visually striking wood sculptures made of single boles and decorated with inlays of guanin (a gold-copper alloy) or shell: there are no extant examples featuring multiple wood components. By the time of Columbus’ arrival in 1492, wooden sculpture is documented as being central to Taíno religious and social practices.

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2 Transverse section of Guaiacum officinale showing a lack of distinct growth rings (image size: 2059 ?m wide by 1544 ?m tall).
Photo: A Wiedenhoeft.

Paired Dating of Pith and Outer Edge (Terminus) Samples from Prehispanic Caribbean Wooden Sculptures by FPL’s Alex Wiedenhoeft and others report paired or multiple dates from 11 wooden sculptures from the Taíno peoples. Dating of wood can be problematic because of the potential reuse of wood and differences in age across a tree from the pith to the sapwood’s outer rings. The nature of Taíno wooden sculpture—carved of dense tropical hardwoods that are still poorly known—makes it even more challenging to sample and date.

The calibrated ages of the pieces published here range from ~AD 700–1500, indicating that the Taíno were producing elaborate sculptures much earlier than previously thought. The results can also be used to generate a growth rate model for species that do not have distinct growth rings, and the models can be used to refine the calibrated ages of pieces. The paired or multiple dates from these carvings confirmed the accuracy of the results, and were also used to construct a growth rate model of what was expected to be a slow-growing species (Guaiacum sp.). This model demonstrates that the boles used to create the sculptures grew on average 1 cm every 6–13 years.

Emerald Ash Borer and Urban Trees

EAB-logoWhat’s the big deal about the emerald ash borer? According to the Colorado Tree Coalition, the emerald ash borer (EAB) has killed millions of ash trees since its discovery in 2002 and the number of dead ash is increasing rapidly. Ash species are abundant in planted and natural areas of urban forests, representing 10–40% of the canopy cover in many communities. Ash trees provide substantial economic and ecosystem benefits to taxpayers, ranging from increased property value, to storm water mitigation, to decreased energy demands.

Our fellow researchers at the USDA Northern Research Station say that widespread ash mortality in urban forests and residential landscapes is having devastating economic and environmental impacts. EAB is predicted to cause an unprecedented $10-20 billion in losses to urban forests over the next 10 years.

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Damage by building: Photo by Joseph O’Brien, USDA Forest Service, courtesy of Bugwood.org.

Why has this little bug become such a huge problem? In its native range, natural enemies, such as parasitic wasps, are thought to keep populations under control. In North America, this beetle has no natural enemies. Because they are not in their original habitat, invasive species rarely have the checks, such as predators and diseases, that keep them from taking over in their native ecosystems. EAB kills all species of ash trees, often within 2 or 3 years after the trees have been infested. The biggest threat by invasive species to our natural resources is their effect on biodiversity.

The primary regulatory strategy is to create quarantine zones by state and federal agencies to limit the spread of potentially infested materials.

So far, the northern United States have been affected the most by the EAB, as the map shows. Reports are coming in, however, showing that the deadly bug is spreading farther south and east.

For scientists, the details of climate change on the invasion rate of nonnative species are still unclear. It depends on the invasive species’ biology, exactly how the climate changes, and what effect climate change has on a given locale. But one effect the experts seem to agree on is that as habitat suitability moves northward with the warming trend of climate change, invasive species’ ranges will expand there, too. Climate change is a key area of  for the Forest Service and FPL, particularly Supervisory Research Forester Ken Skog and his group, the Economics, Statistics and Life Cycle Analysis Research, which is studying the environmental effects of carbon sequestration, among other things.

 

Green Menace: Emerald Ash Borer Lurks Under Cloak of Winter

Here in Madison, Wis., home of the Forest Products Laboratory, all has been covered in snow and ice. But within many of the finest shade trees in our parks and homes lurks big trouble, as the dreaded Green Menace is here. The emerald ash borer or EAB (Agrilus planipennis) is a beetle in the family Buprestidae, which are known as the metallic wood-boring beetles because of their metallic colors. Members of this family are found worldwide.

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Adult emerald ash borer. Photo courtesy of Rachel Arango of the Durability and Wood Protection Research Unit.

History

The EAB is an invasive beetle that was introduced from China, most likely as a hitchhiker on wooden shipping pallets. It was first discovered in 2002 in Michigan and is now thought to have spread to more than a dozen states, including Wisconsin.

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EAB larva. Photo courtesy of Rachel Arango.

Unfortunately, one of the traits about EAB that makes it so deadly is that it is nearly invisible in its early stages of infestation. The flying insects are only about an eighth of an inch wide and they lay their eggs very high in crevices of the trees’ upper branches. Once the eggs hatch, the larvae  bore into the tree and begin feeding on the soft wood beneath (the phloem), where they burrow long galleries. These tunnels affect the tree’s ability to transport water and nutrients and eventually girdle the tree. The larvae develop into pupae, which transform into adult beetles in the spring where the cycle continues. Characteristic D-shaped exit holes that adult beetles produce when they emerge from the tree are often used as indicators of EAB activity. Egg to adult is approximately 1–2 years.

EAB galleries in wood. Photos courtesy of Rachel Arango.

EAB galleries in wood. Photos courtesy of Rachel Arango.

Symptoms of EAB

A number of clues might indicate presence of EAB including, crown die-back, epicormic branching (epicormic branches are shoots arising spontaneously from dormant buds on stems or branches of woody plants), and the D-shaped exit hole.

Our colleagues at the Forest Service Northern Research Station have done major research on the EAB, whereas FPL has been more involved in researching the ways in which damage from EAB may be mitigated and options for utilizing wood from urban trees infested by invasive species.

Researchers are determined to find ways to slow, if not stop, the spread of this pest. Until then, we will continue to find ways to make the most of the damage they leave in their wake.

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An Evolutionary History of Oriented Strandboard

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New house construction with OSB underlayment.

A new FPL report, by retired Wood Technologist John I. Zerbe, Supervisory Research Materials Engineer Zhiyong Cai, and retired Economist George B. Harpole gives us the story behind a product that we all use and take for granted every day.

An Evolutionary History of Oriented Strandboard (OSB) tells us that historically, logging and wood processing residues offered a utilization challenge for those who harvested and manufactured wood products. Logging operations typically left stumps, tapered log butts, tree tops, and limbs for forest fires to remove or to compost into bed­ding for destructive forest insects.

Even after the delivery of logs to a sawmill or plywood plant, residue materials have represented up to 60% of the log volumes delivered. Thus, commercial efforts have attempted to utilize as much of these residue volumes as possible with production of char­coal, poultry bedding, and heating fuels. Forest fires, tepee burners, and burn piles, however, have often provided a quick answer for getting rid of the surplus accumulations of forest and processing residues. Today, with the increased use of logging residues and wood chips for production of OSB panels, about 80% of the wood volume removed from the forest is now processed into marketable products and tepee burners no longer exist for getting rid of processing residues.

The pathway to OSB production appears to have started in the 1920s with production of hardboards from pulp mats that were produced from wood chips. This was the begin­ning for producing composite panel products from wood residue types of materials. Following hardboard production and skipping the pulping step for producing hardboards, the utilization of waste materials was increased in the United States in the 1940s by the production of nonstructural and appearance grades of particleboards. Even as a nonstructural product, the particleboard made in the United States was new compared with plywood.

Manufacturing OSB.

Manufacturing OSB.

But with the decline in the availability of timber suitable for plywood production in the 1970s, the development of technologies for production of structural types of particleboards quickly became a top priority for wood products research. As technology advance­d various products were produced along the way until researchers developed the oriented strandboard or OSB panels we speak of today.

Ideas for particleboard originated in Germany in the 1930s, and the prod­uct yield from harvested trees was only about 40%. Today, with increased use of wood chips and sawdust, logging residues have been reduced to less than 10%, with little to no processing residues to dispose of. OSB is ubiquitous because OSB panels have been essentially a problem-free new commodity wood product. Perhaps no other new wood product has ever been so problem free as OSB com­posite panels.

The Updated Billion-Ton Resource Assessment: A New Publication

A resource assessment published in 2005, commonly referred to as the Billion-Ton Study (BTS), estimated “potential” biomass within the contiguous United States based on numerous assumptions about current and future inventory, production capacity, and technology; the main conclusion of the study was that U.S. agriculture and forest resources have the capability to sustainably produce one billion dry tons of biomass annually.

The Updated Billion-Ton Resource Assessment by Supervisory Research Forester Ken Skog and Mathematical Statistician Patricia Lebow appears in a recent Science Online article.

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The 2011 Billion-Ton Update (BT2) improves on the 2005 BTS in several ways, including a more comprehensive and rigorous model of environmental sustainability. The POLYSYS model is used to estimate supply curves for energy crops, and most resources are estimated at the county level. Further, the update emphasizes the 2012–2030 time period coincident with implementation of the Energy Independence and Security Act of 2007 and U.S. Department of Energy initiatives, rather than on updating the 2050 projection results in the original study.

The 2011 BT2 shows that large quantities of biomass are available while meeting food, livestock feed, industrial, and export demands. The BT2 is consistent with the 2005 BTS in terms of magnitude of the resource potential. Total available resources increase over time as yields increase.

Generally, the scenario assumptions in the updated assessment are much more plausible to show a “billion ton“ resource, which would be sufficient to displace 30% or more of the country’s present petroleum consumption and provide more than enough biomass to meet the 2022 requirements of the Renewable Fuel Standard.

Key Points

  • The updated resource assessment more plausibly shows that large quantities of biomass are available.
  • This “billion ton“ resource is sufficient to displace 30% or more of the country’s present petroleum consumption and provide more than enough biomass to meet the 2022 requirements of the Renewable Fuel Standard.
  • Cooperators include FPL; Oak Ridge National Laboratory, Oak Ridge, Tennessee; WrightLink Consulting, Ten Mile, Tennessee; University of Tennessee, Knoxville, Tennessee; and CNJV, Golden, Colorado.