In the present study, the multiple regression analysis of mass balance equations of seven major geochemical elements (Al, Fe, Ca, Mg, K, Na, Si), among rock, soil, stream water, and precipitation in a watershed was used to simultaneously estimate the rates of rock weathering (RWR) and soil formation (SFR) in two template forest watersheds of Central Japan that had different types of vegetation and bedrock. Our results revealed that Mt. Kasuga watershed (MKW) with a primary evergreen broadleaf forest and gneissic bedrock had lower RWR (1.51 t ha −1 yr −1) and SFR (1.37 t ha −1 yr −1) than those in Yata Hill watershed (YHW) with a semi-deciduous mixed forest and granitic bedrock (RWR = 1.83 t ha −1 yr −1 ; SFR = 1.79 t ha −1 yr −1). Based on the hypothesis that the vegetation effect on the watershed scale mass balance is negligible in a steady state ecosystem, we concluded that the bedrock type can be a main factor causing the difference in RWR and SFR, as gneiss in MKW had smaller amounts of mica and feldspars and is supposed to have the higher resistance than granite in YHW to chemical weathering.

Abstract:© Versita Sp. z o.o. is minimized. Keywords: Lead • 4-(2-pyridylazo)-resorcinol • Colorimetric

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 suburban 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 suburban area of Nara, Central Japan in 2006 and 2011. Basal area increment (BA) 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 BA 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 BA 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 (R 2 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 (R 2 0.17), while suggests that there are other factors that affect the P. grayana growth.

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