Abstract
Cerasus jamasakura and Padus grayana are wild cherry species indigenous to Japan. These wild cherries have high values in secondary forests. However, their population declines due to forest degradation are concerned recently in sub-urban areas. To collect fundamental information on forest ecology, we conducted an assessment on all woody stems in a 2.21 ha research plot in a secondary forest of the sub-urban area of Nara, Central Japan in 2006 and 2011. Basal area increment (ΔBA) during 2006-2011, was calculated for each wild cherry species, based on the measurement of stem diameter at breast height in 2006 and 2011. Through the development of growth prediction models using ΔBA and its natural logarithm as objective variables, we examined the growth of the wild cherries as affected by environmental factors such as indices of neighborhood competition and topography (index of convexity, slope position and slope azimuth) .The decrease in stem density and sum of basal area of C. jamasakura and P. grayana decreased from 2006 until 2011 and the highest frequency of both species in the smallest ΔBA class suggest that the population decline of these species in this site. Our results indicate that a model with a competition index used as an explanatory variable predicted the C. jamasakura growth well (R2＝0.54) and that their growth are significantly affected by the neighboring competitive trees. In contrast, a model developed for P. grayana didn't perform well (R2＝0.17) , while suggests that there are other factors that affect the P. grayana growth.
