Between 1991 and 2008, the panda population in the reserve's breeding center increased from a mere 10 to around 240. And that is why the press dubbed Zhang: "Father of the Panda".
However, if you listen to the man himself, that title only means something when "panda mothers" think of him that way.
"There were times when a panda mother went into labor while I was away, and she would wait for me to come back," he says. "I don't remember how many times a cub was born the moment I entered the door."
What to others may seem like coincidence is to Zhang a sure sign of the bond between him and the pandas.
And those are the memories that the director has been clinging to in the months since May 12.
Another source of strength has come from local villagers, who, despite widespread hunger after the quake, saved many animals in the wild and took them to the center in order to cure their injuries.
"When I first went to Wolong in the early 80s, people were hunting for food and no one gave a damn about wildlife protection," Zhang says. "But pandas are simply so cute that everyone agreed that they should be protected. And that was really the beginning of the change."
Since 2000, encouraged by the director, local people started to plant bamboo on large scale, a measure that not only brought them extra income but also, in retrospect, saved their lives. The bamboo forests mitigated the effects of the landslides, and in many cases stopped the rolling boulders as they ran down the slopes.
All that may explain why people find it hard to accept why a decision was made to evacuate all pandas from the reserve in the aftermath of the earthquake.
Eventually, all but seven of the center's 62 surviving pandas were transported to other places, including Ya'an, another panda breeding base 500 km away from Wolong.
According to Zhang, the bamboo forests in Wolong will be enough for the pandas to live on through the winter. "For local people, they are the promise of hope," he says.
"Why do we care so much about pandas?" the director asks. "Because we care about this space, the same eco-system that we share with them."
"Neither this place nor us will be the same without pandas."
(China Daily December 23, 2008)