Horses in China were found grazing on bamboo plants so aggressively that it risked putting panda populations in jeopardy, according to new research.

In some cases the researchers observed a range of bamboo - the only food pandas eat - completely mowed over by horses.

"It didn't take particular panda expertise to know that something was amiss when we'd come upon horse-affected bamboo patches. They were in the middle of nowhere and it looked like someone had been in there with a lawn mower," said Vanessa Hull, a doctoral student in Michigan State University's Center for Systems Integration and Sustainability.

Hull, along with panda habitat expert Jack Liu, also of MSU, reported the finding in the Journal for Nature Conservation. Their research highlights a hidden-yet-significant conflict that can arise amid conservation efforts.

"Across the world, people are struggling to survive in the same areas as endangered animals, and often trouble surfaces in areas we aren't anticipating," Liu said. "Creating and maintaining successful conservation policy means constantly looking for breakdowns in the system. In this case, something as innocuous as a horse can be a big problem."

China has a large panda conservation program in place, having set aside huge swaths of land for the animal. Local farmers living around the Woolong Nature Reserve reportedly began using the panda forests as a place to graze horses. The move was unexpected, as the Woolong farmers have no traditions of horse-keeping. But for these framers, having a healthy horse is like having an emergency fund for a rainy day. They would not attend to the horses, but when they needed money, the farmers would track the horses down in the panda forests, where they grazed upon bamboo. This "horse in the bank" system became popular, and the region went from having about 25 horses in 1998 to 350 in 2008.

A horse will eat about as much bamboo as a panda, but a herd of 30 horses eating bamboo is enough to incite resource competition. Upon learning this, the researchers presented their finding to Woolong Nature Reserve managers, who proceeded to ban horses from grazing in the reserve.

The finding, however, sheds light on how animals can compete for resources in unexpected places.

"Livestock affect most of the world's biodiversity hotspots," Liu said. "They make up 20 percent of all of the earth's land mammals and therefore monopolize key resources needed to maintain the Earth's fragile ecosystems."