The Ginkgos of Tian Mu Shan

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Abstract
The question of whether or not Ginkgo biloba still exists in the wild has been debated by botanists, without resolution, for almost a hundred years. Most of the controversy has focused on a single population of trees located on Tian Mu Shan (Tian Mu Mountain) in Zhejiang Province, China, a site of human activities for approximately 1500 years. Regardless of its origin, the Tian Mu Shan Ginkgo population is biologically significant by virtue of its long survival in a semi‐natural state under conditions of intense interspecific competition. A total of 167 Ginkgos were counted and measured in the 1018 ha Tian Mu Shan Reserve. Many of the trees were growing on disturbance‐generated microsites, such as stream banks, steep rocky slopes, and the edges of exposed cliffs. Forty percent of the censused individuals were multitrunked, consisting of at least two trunks greater than 10 cm in diameter at breast height. Most of these secondary trunks originated from root‐like “basal chichi,” that are produced at the base of trees that have experienced damage from soil erosion or other factors. No Ginkgos less than 5 cm in basal diameter were found in the mature forests of Tian Mu Shan. This lack of seedling reproduction is caused by several factors: (1) the lack of sunny microsites suitable for seedling growth, (2) seed collection by people, and (3) seed predation by animals. In the absence of successful seedling establishment, secondary trunk formation from basal chichi is the single most important factor in explaining the long term persistence of Ginkgo on Tian Mu Shan.