Tag Archives: biological

Climate change requires new conservation models, Stanford scientists say

In a world transformed by climate change and human activity, Stanford scientists say that conserving biodiversity and protecting species will require an interdisciplinary combination of ecological and social research methods.

By Ker Than

A threatened tree species in Alaska could serve as a model for integrating ecological and social research methods in efforts to safeguard species that are vulnerable to climate change effects and human activity.

In a new Stanford-led study, published online this week in the journal Biological Conservation, scientists assessed the health of yellow cedar, a culturally and commercially valuable tree throughout coastal Alaska that is experiencing climate change-induced dieback.

In an era when climate change touches every part of the globe, the traditional conservation approach of setting aside lands to protect biodiversity is no longer sufficient to protect species, said the study’s first author, Lauren Oakes, a research associate at Stanford University.

“A lot of that kind of conservation planning was intended to preserve historic conditions, which, for example, might be defined by the population of a species 50 years ago or specific ecological characteristics when a park was established,” said Oakes, who is a recent PhD graduate of the Emmett Interdisciplinary Program in Environment and Resources (E-IPER) at Stanford’s School of Earth, Energy, & Environmental Sciences.

But as the effects of climate change become increasingly apparent around the world, resource managers are beginning to recognize that “adaptive management” strategies are needed that account for how climate change affects species now and in the future.

Similarly, because climate change effects will vary across regions, new management interventions must consider not only local laws, policies and regulations, but also local peoples’ knowledge about climate change impacts and their perceptions about new management strategies. For yellow cedar, new strategies could include assisting migration of the species to places where it may be more likely to survive or increasing protection of the tree from direct uses, such as harvesting.

Gathering these perspectives requires an interdisciplinary social-ecological approach, said study leader Eric Lambin, the George and Setsuko Ishiyama Provostial Professor in the School of Earth, Energy, & Environmental Sciences.

“The impact of climate change on ecosystems is not just a biophysical issue. Various actors depend on these ecosystems and on the services they provide for their livelihoods,” said Lambin, who is also  a senior fellow at the Stanford Woods Institute for the Environment.

“Moreover, as the geographic distribution of species is shifting due to climate change, new areas that are currently under human use will need to be managed for biodiversity conservation. Any feasible management solution needs to integrate the ecological and social dimensions of this challenge.”

Gauging yellow cedar health

The scientists used aerial surveys to map the distribution of yellow cedar in Alaska’s Glacier Bay National Park and Preserve (GLBA) and collected data about the trees’ health and environmental conditions from 18 randomly selected plots inside the park and just south of the park on designated wilderness lands.

“Some of the plots were really challenging to access,” Oakes said. “We would get dropped off by boat for 10 to 15 days at a time, travel by kayak on the outer coast, and hike each day through thick forests to reach the sites. We’d wake up at 6 a.m. and it wouldn’t be until 11 a.m. that we reached the sites and actually started the day’s work of measuring trees.”

The field surveys revealed that yellow cedars inside of GLBA were relatively healthy and unstressed compared to trees outside the park, to the south. Results also showed reduced crowns and browned foliage in yellow cedar trees at sites outside the park, indicating early signs of the dieback progressing toward the park.

Additionally, modeling by study co-authors Paul Hennon, David D’Amore, and Dustin Wittwer at the USDA Forest Service suggested the dieback is expected to emerge inside GLBA in the future. As the region warms, reductions in snow cover, which helps insulate the tree’s shallow roots, leave the roots vulnerable to sudden springtime cold events.

Merging disciplines

In addition to collecting data about the trees themselves with a team of research assistants, Oakes conducted interviews with 45 local residents and land managers to understand their perceptions about climate change-induced yellow cedar dieback; whether or not they thought humans should intervene to protect the species in GLBA; and what forms those interventions should take.

One unexpected and interesting pattern that emerged from the interviews is that those participants who perceived protected areas as “separate” from nature commonly expressed strong opposition to intervention inside protected areas, like GLBA. In contrast, those who thought of humans as being “a part of” protected areas viewed intervention more favorably.

“Native Alaskans told me stories of going to yellow cedar trees to walk with their ancestors,” Oakes said. “There were other interview participants who said they’d go to a yellow cedar tree every day just to be in the presence of one.”

These people tended to support new kinds of interventions because they believed humans were inherently part of the system and they derived many intangible values, like spiritual or recreational values, from the trees. In contrast, those who perceived protected areas as “natural” and separate from humans were more likely to oppose new interventions in the protected areas.

Lambin said he was not surprised to see this pattern for individuals because people’s choices are informed by their values. “It was less expected for land managers who occupy an official role,” he added. “We often think about an organization and its missions, but forget that day-to-day decisions are made by people who carry their own value systems and perceptions of risks.”

The insights provided by combining ecological and social techniques could inform decisions about when, where, and how to adapt conservation practices in a changing climate, said study co-author Nicole Ardoin, an assistant professor at Stanford’s Graduate School of Education and a center fellow at the Woods Institute.

“Some initial steps in southeast Alaska might include improving tree monitoring in protected areas and increasing collaboration among the agencies that oversee managed and protected lands, as well as working with local community members to better understand how they value these species,” Ardoin said.

The team members said they believe their interdisciplinary approach is applicable to other climate-sensitive ecosystems and species, ranging from redwood forests in California to wild herbivore species in African savannas, and especially those that are currently surrounded by human activities.

“In a human-dominated planet, such studies will have to become the norm,” Lambin said. “Humans are part of these land systems that are rapidly transforming.”

This study was done in partnership with the U.S. Forest Service Pacific Northwest Research Station. It was funded with support from the George W. Wright Climate Change Fellowship; the Morrison Institute for Population and Resource Studies and the School of Earth, Energy & Environmental Sciences at Stanford University; the Wilderness Society Gloria Barron Fellowship; the National Forest Foundation; and U.S. Forest Service Pacific Northwest Research Station and Forest Health Protection.

For more Stanford experts on climate change and other topics, visit Stanford Experts.

Source : Stanford News


Microscopic “walkers” find their way across cell surfaces

Technology could provide a way to deliver probes or drugs to cell structures without outside guidance.

By David Chandler


 

CAMBRIDGE, Mass–Nature has developed a wide variety of methods for guiding particular cells, enzymes, and molecules to specific structures inside the body: White blood cells can find their way to the site of an infection, while scar-forming cells migrate to the site of a wound. But finding ways of guiding artificial materials within the body has proven more difficult.

Now a team of researchers at MIT led by Alfredo Alexander-Katz, the Walter Henry Gale Associate Professor of Materials Science and Engineering, has demonstrated a new target-finding mechanism. The new system allows microscopic devices to autonomously find their way to areas of a cell surface, for example, just by detecting an increase in surface friction in places where more cell receptors are concentrated.

The finding is described this week in a paper in the journal Physical Review Letters, written by Alexander-Katz, graduate student Joshua Steimel, and postdoc Juan Aragones.

“The idea was to find out if we could create a synthetic, active system that could sense gradients in biological receptors,” Alexander-Katz explains. “Currently, we don’t know of anything that can do that.”

Cells have a way of locating areas that bear a specific kind of chemical signature — a process called chemotaxis. That’s the method used by white blood cells, for example, to locate regions where pathogens are attacking body cells.

“Our system is very simple,” Alexander-Katz says — similar to the way in which bacteria locate nutrients they need. The system, without guidance, samples areas on a surface and migrates toward those where friction is greater — which also correspond to areas where receptors are concentrated.

The system uses a pair of linked particles with magnetic properties. In the presence of a magnetic field, the paired particles begin to tumble across a surface, with first one particle and then the other making contact — in effect, “walking” across the surface.

So far, the work has been carried out on a model cell surface, on a functionalized microscope slide, but the effect should work similarly with living cells, Alexander-Katz says. The team’s goal now is to demonstrate the ability of the microscopic walkers to find their way toward concentrations of receptors in actual living tissue.

The method could potentially have a variety of applications, Alexander-Katz says. For example, it could be developed as a method of locating tumor cells within the body by identifying their surface texture, perhaps in combination with other characteristics.

Such magnetic microwalkers, he adds, could be unleashed to locate areas of interest on various kinds of surfaces, based solely on differences in friction. The particles naturally migrate toward high-friction regions, where they could then be induced to interact with a surface by active molecules attached to them.

“It’s a very versatile system,” Alexander-Katz says, that can be functionalized by attaching other kinds of receptors or binding agents to affect or monitor the target area in different ways.

The next step is to test the approach in more complex settings. The initial work was done with flat surfaces; the team now aims to conduct studies in complex 3-D settings to make sure the process works effectively in situations that more closely resemble a real cellular environment.

The research was supported by the U.S. Department of Energy, the MIT Energy Initiative, and the Chang family.