Basic data for CO2 flux monitoring of a young larch plantation: Current status of a mature, mixed conifer-broadleaf forest stand [Japan]

A yearly increase in atmospheric CO2 is leading to global warming. To moderate global greenhouse conditions, forest ecosystems are expected to act as CO2 sinks. The forest stand structure of a mixed conifer-broadleaf forest was analyzed to gather the basic information needed to evaluate the COi sink capacity of the stand. The total area of the Teshio Experimental Forest of Hokkaido University, located in northern Hokkaido near the border between Japan and the Russian Far East (45degC N, 142degC E), was 13.71 ha. A forest area of 0.25 ha (50m * 50m) was selected for this study. In the site, there were a number of individual species, 2 species of conifers and 13 species of deciduous hardwoods. The frequency distribution of the diameter of breast height (DBH) of the trees exhibited an L-shape. Oak and fir were distributed uniformly while willow and magnolia showed a clump distribution. The total number of trees in the selected area was 155 and the total volume was 52.23 cube m. There were 19 evergreen conifers and 136 deciduous broadleaf trees with total volumes of 11.69 cube m 40.54 cube m, respectively. Dominant species in the order of volume were oak (16.4 cube m), fir, mountain birch, kalopanax, white birch, willow and maple (2.5 cube m). There was a positive correlation between DBH and crown projection area (CPA). The increment of regression line between DBH and CPA was steeper in the early- and late-successional species than that in the increment of gap-phase species and conifers. However, the largest DBH was 41cm for early successional species and 60-67cm for late successional species and conifers. Based on the specific gravity of each species, at present, the amount of CO2 stored in stems was estimated to be 1702.9ton (124.2ton CO2/haE-1; 84.5ton-haE-1 for aboveground biomass). The need for further studies to estimate biomass of Sasa sp. and net ecosystem production are discussed.