Ancient Maya Practiced Forest Conservation

Image 1: This temple in Tikal, labeled "Temple 1" by researchers, was built by the ancient Maya somewhere between 682 and 734 A.D., and was possibly completed after Jasaw Chan K'awiil's death. It was the second temple built in the area.

Image 2: Nick Dunning, Vern Scarborough and David Lentz (l-r) take a soil core to measure the depth of one of several large reservoirs that surround the site of Tikal, the ancient Maya city. Lentz was principal investigator for a National Science Foundation-supported study at the site.

Image 3: This temple in Tikal, labeled "Temple 5" by researchers, was built by the ancient Maya somewhere between 768 and 780 A.D.

More About These Images

David Lentz, a biology professor at the University of Cincinnati (UC), received a grant from the National Science Foundation (NSF) to study the interaction between the ancient Maya of Tikal and their local environment.

Lentz's research found that the Maya practiced forest conservation early on. They were not allowed to cut down certain forests of virgin timber--some of which were over 200 years old--which the researchers dubbed the "sacred groves." "From our research we have learned that the Maya were deliberately conserving forest resources," says Lentz. "Their deliberate conservation practices can be observed in the wood they used for construction and this observation is reinforced by the pollen record." But later, the Maya abandoned this practice.

When Jasaw Chan K'awiil took over as ruler during the Late Classic period, the Maya rebuilt the city of Tikal. This rebuilding included construction of enormous temples that required large, straight trees whose wood could withstand the weight of tons of heavy stone. Lentz found that the Maya used the sacred groves for this purpose but soon ran out of timber, which came from the Manilkara zapota (or sapodilla) tree. Sapodilla wood is soft when first cut but once it dries it's as hard as iron, making it an ideal building material for the temples. Once the sapodilla were gone, the Maya began using inferior wood from the Haematoxylon campechianum (logwood or ink wood) trees. Logwood trees, which grow in swamps, are hard like iron from start to finish. The archways to the temples built using logwood were less ornate because the tree grows crooked and is not as lofty as the sapodilla.

The earlier temples (labeled 1 through 4 by the researchers) are quite large. The beams over the doorways (called Lintels) of Temple 4 are the largest of them all, whereas Temples 5 and 6 are much smaller. But Lentz found that for Temple 3, the last temple built, the Maya went back to using sapodilla. Lentz believes they may have replanted the sacred groves after cutting them down (after 40 years, you would have a tree large enough to use for building). Also, Lentz says, things began going downhill for the Maya at this point. "Perhaps they reasoned that the gods didn't like the new style of temple and they needed to return to the construction style of earlier, and more prosperous, times."

To learn more about this research, see the UC news story UC Scientists Determine That Ancient Maya Practiced Forest Conservation 3,000 Years Ago. [Research supported by NSF grant BCS 08-10118.]

(Date of Image: February/March 2009)

Credit: Department of Biological Sciences, University of Cincinnati

Global Extinction: Gradual Doom as Bad as Abrupt

The deadliest mass extinction of all took a long time to kill 90 percent of Earth's marine life--and it killed in stages--according to a newly published report.

It shows that mass extinctions need not be sudden events.

Thomas Algeo, a geologist at the University of Cincinnati, and 13 colleagues have produced a high-resolution look at the geology of a Permian-Triassic boundary section on Ellesmere Island in the Canadian Arctic.

Their analysis, published today in the Geological Society of America Bulletin, provides strong evidence that Earth's biggest mass extinction phased in over hundreds of thousands of years.

About 252 million years ago, at the end of the Permian period, Earth almost became a lifeless planet.

Around 90 percent of all living species disappeared then, in what scientists have called "The Great Dying."

Algeo and colleagues have spent much of the past decade investigating the chemical evidence buried in rocks formed during this major extinction.

The world revealed by their research is a devastated landscape, barren of vegetation and scarred by erosion from showers of acid rain, huge "dead zones" in the oceans, and runaway greenhouse warming leading to sizzling temperatures.

The evidence that Algeo and his colleagues are looking at points to massive volcanism in Siberia as a factor.

"The scientists relate this extinction to Siberian Traps volcanic eruptions, which likely first affected boreal life through toxic gas and ashes," said H. Richard Lane, program director in the National Science Foundation's (NSF) Division of Earth Sciences, which funded the research.

The Siberian Traps form a large region of volcanic rock in Siberia. The massive eruptive event which formed the traps, one of the largest known volcanic events of the last 500 million years of Earth's geologic history, continued for a million years and spanned the Permian-Triassic boundary.

The term "traps" is derived from the Swedish word for stairs--trappa, or trapp--referring to the step-like hills that form the landscape of the region.

A large portion of western Siberia reveals volcanic deposits up to five kilometers (three miles) thick, covering an area equivalent to the continental United States. The lava flowed where life was most endangered, through a large coal deposit.

"The eruption released lots of methane when it burned through the coal," Algeo said. "Methane is 30 times more effective as a greenhouse gas than carbon dioxide.

"We're not sure how long the greenhouse effect lasted, but it seems to have been tens or hundreds of thousands of years."

Much of the evidence was washed into the ocean, and Algeo and his colleagues look for it among fossilized marine deposits.

Previous investigations have focused on deposits created by a now vanished ocean known as Tethys, a precursor to the Indian Ocean. Those deposits, in South China particularly, record a sudden extinction at the end of the Permian.

"In shallow marine deposits, the latest Permian mass extinction was generally abrupt," Algeo said. "Based on such observations, it has been widely inferred that the extinction was a globally synchronous event."

Recent studies are starting to challenge that view.

Algeo and co-authors focused on rock layers at West Blind Fiord on Ellesmere Island in the Canadian Arctic.

That location, at the end of the Permian, would have been much closer to the Siberian volcanoes than sites in South China.

The Canadian sedimentary rock layers are 24 meters (almost 80 feet) thick and cross the Permian-Triassic boundary, including the latest Permian mass extinction horizon.

The investigators looked at how the type of rock changed from the bottom to the top. They looked at the chemistry of the rocks and at the fossils contained in the rocks.

They discovered a total die-off of siliceous sponges about 100,000 years earlier than the marine mass extinction event recorded at Tethyan sites.

What appears to have happened, according to Algeo and his colleagues, is that the effects of early Siberian volcanic activity, such as toxic gases and ash, were confined to the northern latitudes.

Only after the eruptions were in full swing did the effects reach the tropical latitudes of the Tethys Ocean.

The research was also supported by the Canadian Natural Sciences and Engineering Research Council and the National Aeronautics and Space Administration Exobiology Program.

In addition to Algeo, co-authors of the paper are: Charles Henderson, University of Calgary; Brooks Ellwood, Louisiana State University; Harry Rowe, University of Texas at Arlington; Erika Elswick, Indiana University, Bloomington; Steven Bates and Timothy Lyons, University of California, Riverside; James Hower, University of Kentucky; Christina Smith and Barry Maynard, University of Cincinnati; Lindsay Hays and Roger Summons, Massachusetts Institute of Technology; James Fulton, Woods Hole Oceanographic Institution; and Katherine Freeman, Pennsylvania State University.

 
-NSF-