Soil respiration rates and their relating micro-environmental factors were measured in September in 1999 and 2000 to clarify the controlling factors of soil respiration rates in a cool temperate broad-leaved deciduous forest. The study site was located on a southwestern slope of Mt. Norikura at about 1,400 m asl. The site contained an experimental area of one hectare, subdivided into 100 sub-plots, each 10 m by 10 m in size. The rate of soil respiration was measured by the closed chamber method. The micro-environmental factors examined included temperature (air, soil), soil water contents, CO2 concentration, biomass (tree, understory vegetation), soil nitrogen and carbon contents, thickness of soil layers, and topographic conditions. Results of multiple regression analysis were as follows: 1) Rate of soil respiration was strongly affected by topographic conditions, being 5-12% higher at the summit of the hill and 2.5% lower at the bottom of the valley, compared with the average. 2) Multiple regression analysis of 2-year data using the stepwise method clarified that VSR=27.94 Xts-0.58 XCO2+3.26 Xa+17.89 Xl-1.74 Xw+118.44 (R2=0.707) where VSR is the soil respiration rate, Xts the soil temperature at - 10 cm, XCO2 the CO2 concentration at 0 cm, Xa the relative altitude, Xl the thickness of litter layers and Xw the soil water content. 3) The measured soil respiration rate was high in 1999 (408.2 mgCO2m-2h-1 on average) and low in 2000 (354.0 mgCO2m-2h-1 on average), reflecting previous rainfall. The soil water contents in 1999 and 2000 were 33.6% and 20.8%, respectively. Environmental factors in 1999 were still unstable after plenty of rainfall. The high moisture content in 1999 seemed to conceal the effects of other micro-environmental factors.
|ジャーナル||Japanese Journal of Ecology|
|出版ステータス||Published - 2003 4月|
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