Site Description

The study site was a cool-temperate deciduous forest located on the gently sloping (30°) terrain at the Sugadaira Montane Research Center (SMRC; 36°36/N 138°210E, 1,300 ma.s.l.), University of Tsukuba, Nagano Prefecture, central Honshu, Japan (Fig. 1). The mean annual temperature and precipitation over the last 30 years, recorded by the SMRC meteorological station, were 6.3°C and 1210 mm, respectively. The monthly mean air temperature during the study period (2002-2004) ranged from -10°C in January to 20°C in July or August, and the annual mean air temperature was 6.5, 6.3, and 7.2°C in 2002, 2003, and 2004, respectively (Fig. 2). Daily precipitation data showed no long-term dry period during the study period. Heavy rain events occurred in early summer in 2002 and early summer and autumn in 2004, but none were recorded in 2003. Annual precipitation was 1438, 1236, and 1648 mm in 2002, 2003, and 2004, respectively. Thus, 2004 was a hot, rainy year. The forest floor was covered continuously by snowpack from December to mid-April each year (the maximum snowpack depth of 120 cm was recorded on 5 March, 2003).

The study forest is a 50-year-old secondary (coppice) forest dominated by Quercus crispula with Betula platyphylla var. japonica being subdominant. The tree density in the canopy layer is 2,000 shoots ha-1, and there is little understory vegetation. The soil is a dark-colored, humic Andosol. The soil profile is composed of an O horizon (< 3 cm thick), an A horizon (40-50-cm

Rube Goldberg Design Sheets

Figure 1: Location of the study site in Nagano Prefecture, Japan.

Figure 1: Location of the study site in Nagano Prefecture, Japan.

O 30

is 10

O 30

is 10

150 100

150 100

1 50

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Figure 2: Seasonal variations in daily mean air temperature (a), daily precipitation (b), and snow depth (c) during the study period (2002-2004).

thick), and a B horizon (deeper than 50 cm). Physicochemical analyses were carried out for litter and mineral soil. A 20 x 20 cm area of litter was sampled at three sites in November 2004, after all leaves had fallen. The litter on the forest floor contained 0.3 kg Cm-2. Three soil cores of 100 ml were collected at the depths of 0-10, 10-20, and 20-30 cm in the A horizon in August 2004. Bulk density decreased from 0.33 to 0.23 g cm-3 with increasing soil depth. At 0-10 cm air-filled porosity was 80% and pH was 5.2. The total carbon and nitrogen contents, respectively, of the study forest soil were 15 and 0.93% for 0-10 cm, 13 and 0.76% for 10-20 cm, and 9 and 0.56% for 20-30 cm. The concentrations of NH+-N and NO3-N were 29.1 and 2.83 mgNg-1dw, respectively.

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