The Inner Life of Trees

Dendrochronologist Kathelyn Paredes Villanueva sheds light on Bolivia’s forests, one tree ring at a time

Array of Morado tree cross sections

Kathelyn Paredes Villanueva headshot

Kathelyn Paredes Villanueva

AGE: 29
HOME: Santa Cruz de la Sierra, Bolivia
CAUSE: Using data about tree rings to evaluate the effects of various environmental and man-made factors on forest health

Kathelyn Paredes is used to telling people that a certain decoration in her house is not for sale. “My father is an auto mechanic, so there are always clients stopping by for car repairs,” she says. “But then they see this beautiful cross-section of a tree on display in the front hall, and many of them ask to buy it.”

Paredes, who lives in Bolivia, is a researcher in the field of dendrochronology—the study of changes in the climate and environment through comparing the growth rings in trees. It’s a discipline she discovered when her college, the Universidad Autónoma Gabriel René Moreno, received funding for some new forestry laboratories. She was fascinated by the one with dendrochronology equipment.

Paredes read everything she could on the subject before proposing a study of Machaerium scleroxylon, or morado, a valuable timber species grown in Bolivia. After the initial research, she spent a year and a half analyzing morado samples using the lab’s special microscope and software programs.

  • Cross-section of a morado tree stump

    The morado, or Bolivian rosewood, is a species of timber that grows exclusively in the eastern central part of the South American continent. In Bolivia, it grows in the tropical dry forest.

    Morado wood is harvested to manufacture a wide variety of products—from beams and lathe parts to fine furniture, guitars and pool cues.

  • Cross-section of a morado tree stump

    The morado’s flowering cycle fluctuates from yearly to every two or three years.

    Trees in tropical dry forests have very slow growth rates, averaging only 0.067 inches each year.

  • Cross-section of a morado tree stump

    The pale yellowish section in each disc is sapwood, the softer layers of recently formed wood just under the bark.

    The darker purplish area at the center of each sample is heartwood—the oldest, densest and hardest part of the trunk.

  • Cross-section of a morado tree stump

    The morado’s trunk usually has ribbed bark and a hollow at the center caused by rot.

  • Cross-section of a morado tree stump

    The morado is one of the trees most vulnerable to damage from fires in the tropical dry forest.

    The morado population has declined considerably in recent years. Young morado trees have a high mortality rate—and the main cause of death is forest fires.

"It’s very complicated," Paredes says of the process. "There are a lot of false tree rings, and if the trunk sample isn’t circular you have to follow at least three different radii to get a proper count."

With the help of several researchers from Spain, Paredes published the first tree-ring chronology of the morado, arguing that logging companies need to wait much longer between morado harvests because of the tree’s slow growth cycle.

Paredes is now coauthoring a study of another timber species, and WWF’s Russell E. Train Education for Nature Program has provided much-needed funding to support her research over the past few years. In addition, Paredes says she could never have made such progress without mentorship from her Spanish colleagues and several others at universities in Australia, Arizona and the Netherlands.

She also says that while scrutinizing the intricacies in wood samples she has found some wisdom among the hard data. “I think that dendrochronology is also a lesson for life, because by identifying and counting tree rings I am learning to be patient.”

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