The fast-growing population of Formosan sambar, a protected wildlife species endemic to Taiwan, has ecologists worried that the animal’s behavior of stripping bark and rubbing their antlers against trees is jeopardizing the alpine ecosystem within Yushan National Park.
According to government statistics, the Formosan sambar population in the park in Nantou County has increased 17-fold over the past decade.
The number of Formosan sambar captured by an automatic camera installed on Yushan (玉山) by Tunghai University professor Lin Liang-kong (林良恭) also climbed from 0.5 per 1,000 hours in 2003 to about 8.8 between 2009 and 2011.
A research team led by National Taiwan University professor Lee Ling-ling (李玲玲) also found in recent years that the population density of the protected species within a 1km radius of section two of the Southern Central Ridge Trail (SSCRT) was between 77 and 90 per square kilometer.
However, academics have yet to be able to calculate the total population of Formosan sambar nationwide.
Raising concern over the possible adverse impact of the rapidly expanding Formosan sambar population on the forest ecosystem, Lin Chung-yi (林宗以), a doctoral student at National Taiwan University’s Institute of Ecology and Evolutionary Biology, said the species’ behavior could be detrimental to the ecosystems they inhabit.
“Based on my investigations, the Formosan sambar feeds on a total of about 150 tree species, and more than 8,000 trees within a 10m radius of the SSCRT have been damaged by the animal, resulting in a mortality rate of nearly 50 percent for mature trees and of up to 80 percent for young trees in the area,” Lin Chung-yi said.
Where there are Formosan sambar, no young hemlocks or firs can survive, Lin Chung-yi said, adding that the animal had impeded the natural renewal process of the forest.
Lin Chung-yi said that in general, ground cover plants could be seen covering about 80 percent of the areas surrounding hemlocks, but that figure dropped to only between 10 percent and 45 percent in areas saturated with Formosan sambar.
“Also, the average height of Yushania niitakayamensis that used to thrive in the habitats of Formosan sambar has fallen to between 30cm and 50cm, from between 3m and 5m,” Lin Chung-yi said.
Echoing Lin Chung-yi’s view, Lin Liang-kong said that because the Formosan sambar had almost no natural enemy, its high-altitude habitats had gradually expanded to also cover medium-altitude areas.
“If this pace continues, the species could soon enter our tea plantations or orchards and eventually intrude on human habitats,” Lin Liang-kong said.
However, some academics are less concerned about the Formosan sambar’s impact on the environment.
Former Providence University president Chen Yu-feng said that while some young hemlocks and firs might have died because of the Formosan sambar’s innate behavior, its population expansion will slow naturally.
“The animal’s impact on the ecosystem is within reason. The larger its population grows, the less food the species can feed on, and that will naturally curb its population expansion,” Chen said.
Chen said that what was more alarming was the promulgation of regulations governing Aboriginal hunting practices in June last year, which enabled Aborigines to hunt a multitude of protected animals, including Formosan sambar, to honor their traditional cultures and rituals.