According to a 2001 research by Dr. Jianguo Liu of Michigan State University, the rate of destruction is higher after the reserve's creation than before its creation. Using NASA's satellite images and records of the number of people there, Liu's research team concluded that due to tourism and the increase in the number of people, the reserve is facing an unprecedented threat. "Tourists do not think they have an impact on panda habitat, but indirectly each visitor has some impact," Liu said. "We do not see ourselves as a destructive force, but we are."