NSF DISCUSSES THE FUTURE OF THE WHITEBARK PINE

Whitebark Pine.  Credit:  U.S. Forest Service/ Wikimedia. 

FROM: NATIONAL SCIENCE FOUNDATION

Whitebark Pine Trees: Is Their Future at Risk?
There's trouble ahead for the whitebark pine, a mountain tree that's integral to wildlife and water resources in the western United States and Canada.


Over the last decade, some populations of whitebark pines have declined by more than 90 percent. But these declines may be just the beginning.

New research results, supported by the National Science Foundation (NSF) and published today in the Journal of Ecology, suggest that as pine stands are increasingly fragmented by widespread tree death, surviving trees may be hindered in their ability to produce their usually abundant seeds.

"With fewer seeds, you get less regeneration," says ecologist Joshua Rapp, affiliated with NSF's Harvard Forest Long-Term Ecological Research (LTER) site and lead author of the paper.

Whitebark pine populations vary between producing a high number of seed cones some years, and a low number of seed cones other years.

This variation depends on four factors: male pollen cones, female seed cones, wind and proximity.

Each year, pollen from male cones is carried on the air to fertilize female seed cones perched atop nearby trees.

"In low-cone years, less pollen is released, reaching extremely few female cones," says Elizabeth Crone, senior ecologist at the NSF Harvard Forest LTER site and co-author of the paper.

"But as more and more whitebark pines die, every year becomes a low-cone year."

In isolated pockets of trees, the gene pool is also diminished, meaning the seeds produced may be less viable over time.

"For decades, researchers have struggled to understand why many different organisms--trees, fish, corals, insects--from various habitats reproduce synchronously and at certain intervals," says Saran Twombly, program director in NSF's Division of Environmental Biology, which funded the research.

"By combining field data on seed and pollen production for whitebark pines with models that simulate mature cone production, this study helps to answer that question for these pines."

To reach their conclusions, the scientists had to look back in time.

They inspected branches from seven whitebark pine sites in western Montana, counting the scars left by pollen cones and seed cones.

"All the years with a high number of seed cones had one thing in common: a high number of pollen cones," says Rapp. "The success of the seeds seems to depend on the amount of pollen produced."

Whitebark pine seeds are an essential food source for many animals in mountain habitats.

The Clark's Nutcracker, a mountain bird, can store up to 100,000 seeds in underground caches each year. Squirrels also store thousands of seeds underground.

A diminished number of seed cones has an effect on grizzly bears, the scientists say; the bears regularly raid squirrel seed caches to prepare for winter hibernation.

"In the past, low years for whitebark pine cones have led to six times more conflicts between grizzlies and humans, as hungry bears look for food in campgrounds," says Crone.

"Now, concerns about viability of whitebark pine populations are one of the main reasons grizzly bears in Yellowstone National Park are still listed as threatened under the Endangered Species Act."

Birds, squirrels and bears are not the only species that depend on whitebark pine.

Vast stands of whitebark pine help to maintain the mountain snowpacks that provide water to more than 30 million people in 16 U.S. states each year.

Whitebark pines are often the only trees at the highest elevations. Their branches retain snow as it blows across gusty mountaintops. Their shade moderates snow-melt in the spring, keeping flows down the mountain in check.

A small percentage of whitebark pine trees have outlived the ongoing destruction by pests and disease. These trees are the next area of focus for Crone's team.

"We want to find out whether the surviving trees are still producing cones," Crone says. "They represent the future of whitebark pines."

-NSF-

EXPEDITION STUDYING GEOLOGIC PRCESSES AND CLIMATE HISTORY

 

Malaspina Glacier (from space) is a piedmont glacier: it's along the foot of a mountain range. Credit: NASA

FROM: NATIONAL SCIENCE FOUNDATION

Expedition to the Gulf of Alaska: Scientists Study Coastal Mountains and Glaciers

Geologists aboard the scientific ocean drilling vessel JOIDES Resolution have embarked on their next adventure: studying glaciers to learn how Earth's geologic processes relate to the planet's climate history.

In the waters near Alaska's stunning coastal glaciers, the researchers are on Integrated Ocean Drilling Program (IODP) Expedition 341: Southern Alaska Margin Tectonics, Climate and Sedimentation.

The ship set sail today from Victoria, British Columbia. The expedition will conclude on July 29, 2013.

"Its scientists are examining the relationship between mountain-building, glaciation and climate," says Jamie Allan, program director in the U.S. National Science Foundation's (NSF) Division of Ocean Sciences, which supports IODP.

"This interplay happens not only in Alaska but in other parts of the world," says Allan. "New insights into these processes will help scientists better understand climate history and change, and how mountain landscapes form."

Led by co-chief scientists John Jaeger of the University of Florida and Sean Gulick of the University of Texas at Austin, an international team of researchers will collect and study sediments from five locations in the Gulf of Alaska.

They will investigate interactions between long-term climate change, including the fluctuations of large glaciers, and how mountains form.

The geologists will also conduct research on the transport of sediments from the mountains to the deep sea.

Because glaciers can erode and carry with them large amounts of rock, these rivers of ice can dramatically alter the landscape.

By rapidly decreasing the overall amount of rock in areas they scour, glaciers can also alter mountain ranges and cause uplifting--sometimes in less than one million years. In geologic terms, a relatively short time span.

"Mountains grow when numerous faults thrust layers of rock on top of each other," Gulick says. "We're asking whether this increases in locations with lots of erosion, such as beneath Alaska's glaciers."

The mountains of southern Alaska "have the perfect combination of large glaciers and rapidly uplifting mountains to test this idea," says Jaeger.

"We know very little about the long-term history of these glaciers," he says, "relative to what we know about other large ice sheets in, for example, Greenland and Antarctica."

The scientists are also comparing the advance and retreat of the Northern Cordilleran Ice Sheet with those of other major ice sheets. During the last 2.6 or so million years, the Cordilleran Ice Sheet periodically covered a large part of North America.

They also plan to obtain a record of Earth's magnetic field reversals recorded in the Gulf of Alaska, and look at ocean circulation changes and their effects on Earth's carbon cycle during transitions into and out of ice ages.

"Thousands of tourists sail through the Gulf of Alaska each year to see the dramatic landscapes created by these glaciers," Jaeger says.

Jaeger hopes that, in addition to many scientific benefits, "the findings from this expedition will provide tourists with a sense of how dynamic that landscape truly is."

The Integrated Ocean Drilling Program (IODP) is an international research program dedicated to advancing scientific understanding of the Earth through drilling, coring and monitoring the subseafloor.

The JOIDES Resolution is a scientific research vessel managed by the U.S. Implementing Organization of IODP (USIO). Texas A&M University, Lamont-Doherty Earth Observatory of Columbia University and the Consortium for Ocean Leadership comprise the USIO.

IODP is supported by two lead agencies: the U.S. National Science Foundation and Japan's Ministry of Education, Culture, Sports, Science and Technology.

Additional program support comes from the European Consortium for Ocean Research Drilling, the Australia-New Zealand IODP Consortium, India's Ministry of Earth Sciences, the People's Republic of China's Ministry of Science and Technology, the Korea Institute of Geoscience and Mineral Resources and Brazil's Ministry of Education.

-NSF-