Structure and stem growth of multi-stemmed trees of Fagus engleriana in China

Summary

Fagus engleriana Seem. occurs in the mountains of southern China. It has a multi-stemmed form at several sites, but it is single-stemmed at other sites. It is not known whether this tree naturally develops the multi-stemmed form at all sites of its range. This paper describes the occurrences of multi-stemmed F. engleriana at eight sites that are spread over its range. The clonal structure and stem growth patterns for selected F. engleriana individuals are also given. Our results suggest that F. engleriana is able to develop a multi-stemmed form at all sites of its range. The beech clones examined usually had closed centres, suggesting that they were younger than the Japanese Fagus japonica clones that have open centres. There were usually dominant and suppressed stems within the F. engleriana clones. Often, the dominant and some suppressed stems within a clone were of similar-age and had strong initial stem-radial growth rates. These similar-aged stems probably emerged in a large opening. The suppressed stems usually had radial growth rates that were initially similar to, but later much less than that of the dominant ones. At one site that was intensively studied, decrease of stem growth with increase of stem size was found in the multi-stemmed beech but not in single-stemmed Fagus hayatae Palibin ex Hayata. Both species had comparable initial radial growth rates. At this latter site there were two large peaks in the ages of all F. engleriana stems sampled, suggesting two major disturbances occurred in the past. F. engleriana occurs mainly in the northern part of Chinese Fagus range, where beech seed production is rather low, and in forests where dense bamboo undergrowth restricts establishment and survival of seedlings. Vigorous sprouting is probably beneficial to F. engleriana enabling it to persist in these habitats.