Natural disturbance and tree species coexistence in an old‐growth beech ‐ dwarf bamboo forest, southwestern Japan

Abstract

Abstract. The structure and composition of a cool‐temperate old‐growth beech (Fagus crenata) ‐ dwarf bamboo (Sasa spp.) forest, partially affected by landslide disturbance, in the Daisen Forest Reserve of southwestern Japan, were investigated in relation to forest floor and canopy conditions. All stems ≥ 4 cm DBH were mapped on a 4‐ha plot and analyses were made of population structure, spatial distribution and spatial association of major tree species. The dominant species, F. crenata, which had the maximum DBH among the species present, had the highest stem density. However, for other species, larger‐sized species had lower stem density with few smaller stems or saplings, while smaller‐sized species had higher stem density with many smaller stems or saplings. Canopy trees of F. crenata were distributed randomly in the plot, while its stems in the other layers and all other species were distributed patchily. Small patches represent gap‐phase regeneration. Larger patches correlate with landslide disturbance, difference in soil age, or the presence/absence of Sasa. Cluster analysis for spatial associations among species and stems in the different layers revealed that the forest community consists of several groups. One main group was formed on sites not covered with Sasa. This group contained a successional subgroup (from Betula grossa to Acer mono and/or F. crenata) initiated by landslide disturbance and a subgroup of tree species that avoid Sasa. Another group was formed on sites with mature soils covered largely with Sasa. This contained associations of canopy trees of F. crenata and smaller‐sized tree species such as Acanthopanax sciadophylloides and Acer japonicum. It is found that the community of this old‐growth beech forest is largely organized by natural disturbance and heterogeneous conditions of the forest floor (difference in soil age and presence/absence of Sasa). The existence of these different factors and the different responses of species to them largely contribute to the maintenance of tree species diversity in this forest.; Keywords: Cluster analysis; Fagus crenata; Forest dynamics; Gap; Landslide; Spatial pattern.

Community Composition and Tree Population Structure in Undisturbed and Disturbed Tropical Semi-Evergreen Forest Stands of North-East India

“…Variation in the density of forest understories across sites is important for the maintenance of tree diversity as they can compete with the seedlings of trees [25,65,67] and could lead to ambiguous evidence for the importance of canopy gaps in maintaining tree diversity [5,23]. [2], in their study on changes in species richness and abundance with experimental disturbance in old field plant communities, observed that the impact of disturbance on species richness depends largely on the nature of the dominance and rates of successional or seasonal change of the community.…”

Stand structure and dynamics during a 16-year period in a sub-boreal conifer–hardwood mixed forest, northern Japan

“…The spatial association between saplings, recruits and canopy trees was analyzed by using Iwao's ω index (Iwao, 1977), which has often been used to analyze the spatial association between two populations (Kohyama et al, 1994;Yamamoto et al, 1995;Manabe and Yamamoto, 1997;Takahashi et al, 2001). This index is calculated by the following equations:…”

“…Forest structure and dynamics of this type of forest ecosystem have often been examined in relation to disturbance regime (Ishikawa and Ito, 1989;Osawa, 1992). For example, several researchers have shown discontinuous age and size distributions and discussed the importance of major disturbances for species coexistence (Oliver and Stephens, 1977;Ishikawa and Ito, 1989;Yamamoto et al, 1995;Abrams and Orwig, 1996;Sano, 1997). Return times for major disturbances are unpredictable, and sometimes exceed more than a millennium (Lorimer, 1977;Canham and Loucks, 1984;Whitney, 1990).…”

Análisis florístico sucesional en la estación biológica Cerro Huitepec, Chiapas, México

“…Chusquea foliosa) resulta imprescindible, ya que bajo condiciones de poca intervención del bosque se ha encontrado que esta planta puede desplazar a numerosas especies locales (p. ej. Yamamoto et al, 1995).…”