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Future of millions depends on conservation of Tibet’s keystone species

January 05, 2011

In the natural world, all species play a role in their environment. However, not all species are created equal. Most ecosystems of the planet contain a keystone species, an animal that has a disproportionate effect on its environment relative to its biomass.

President’s Professor and renown conservationist Andrew Smith from the ASU School of Life Sciences has been studying the biology and environmental impacts of one particular animal for more than 30 years on the Tibetan plateau.

Although the Chinese government treats the pika as an agricultural pest, Smith believes the future of millions of people depends considerably on the efforts to protect and restore the habitats of the diminutive Tibetan pika (Ochotona curzoniae).

Over the past 40 years, the Chinese government has sponsored the systematic poisoning of pikas in wintertime, most recently using grain laced with botulin c strain toxin (Clostridium botulinum).

In the last three years, the poisoning area has grown to encompass 320,000 square kilometers – an area three quarters the size of California. The Tibetan plateau represents 25 percent of the area of China.

“It became very clear to me early on that in areas where they had poisoned the pikas that most of the native species of mammals and even ecosystem functions in the Tibetan plateau had disappeared or been greatly diminished,” Smith says. “Given these observations, I framed the plateau pika as a keystone species.”

When you couple the magnitude of the poisoning area with the role the pikas play in the Tibetan plateau, the death of the pikas leads to multiplied negative outcomes in the ecosystem.

Much of the work Smith and his graduate students have been doing in recent years is to document different aspects of the pika’s biology and its role as an ecosystem engineer.For example, there are few trees in the plateau, so many species of birds use pika burrows as their nesting grounds. When the pikas die, birds must nest elsewhere or die as a result of exposure to poisoned burrows. Without the pikas, birds of prey lose their major food source or die should they eat a poisoned pika.

Unfortunately, Smith’s conservation arguments and research for protecting the Tibetan pika have not changed policies in China. Therefore, Smith and his graduate assistant Max Wilson have now framed the impetus to protect the Tibetan pika as an economic issue.

In 2010, thanks to funding and support from the Phoenix Zoo, Smith and Wilson conducted hydrology research in the area, measuring infiltration rates and contrasting areas where pikas live versus those where they have been eliminated.

The data collected so far point to a direct correlation between the killing of the pikas with increased probability of erosion, flooding of rivers downstream and considerable negative economic impacts.

Sometimes called “The Roof of the World,” the Tibetan Plateau is the birthplace of the Mekong, Huang He, Salween, Yangtze, Tsangpo and Ganges rivers.

“What happens on the plateau, ultimately affects millions of people – estimated as much as 40 percent of people in the world in the downstream drainages of these rivers,” Smith says.

How do little pikas affect the biggest rivers in Asia? Aside from serving as seasonal nests, pika burrows function as a network of underground channels letting the soil breathe and absorb water like a sponge.

“Think of it this way, what holds more water, a sponge or a rock? In these areas water is now running off immediately instead of being slowly released from the soil," Wilson says.

Aside from the economic costs of poisoning pikas, Smith and Wilson hope to show that the disappearance of the Tibetan pika will generate additional costs due to damage from flooding and in turn loss of agricultural production.

Moreover, long-term erosion will also have drought-like effects on the region due to significant ground water retreat as water tables become depleted.

“The interesting thing about water, especially compared to any other ecosystem service in the world like phosphorus or nitrogen, is that it is so singularly defined by where the water starts – and this is where the water starts,” Wilson says. “We have to get that right before we can get anything downstream correct.”

Smith and Wilson have completed their first year of work for what is scheduled to be a two-year study in Tibet. In the past summer Smith and Wilson worked on the drainages of the Mekong, Yangtze and Huang He rivers.

Smith also has received a $1 million grant from the National Science Foundation to conduct further ecological studies in the region along with five other researchers. But the most pressing task in the coming months will be to measure more river drainages and gather sufficient data to demonstrate the link between pikas and the water resources of Tibet.