Invasion of Korean pine (Pinus koraiensis) seedlings into an oak [Quercus mongolica] forest in Korea: Biomass, leaf mass per area, chlorophyll and nutrients

The study aimed to estimate the standing biomass, nutrient distribution, leaf mass per area (LMA) and chlorophyll of Korean pine (Pinus koraiensis S. et Z.) seedlings after harvesting of overstory Quercus mongolica where Korean pine seedlings grow from seeds transported by red squirrels. Three years after harvesting, biomass, nutrient distribution, LMA and chlorophyll were measured, and allometric equations were applied to estimate the biomass of the foliage, branches, stems and roots of seedlings. Heights and diameters of Korean pine seedlings showed a reverse J-shaped distribution. Total biomass (kg/ha) of Korean pine seedlings was 3,627 in the harvested stand and 1,432 in the control stand. The amounts of foliage were higher in both stands compared to other artificially planted Korean pine seedlings. The ratio of foliage biomass to total biomass was 32% in the harvested stand and 42% in the control stand. There were no significant differences in N and P concentration between the two stands among the different parts of the Korean pine seedlings. Total N and P contents were 22.50kg/ha and 2.48kg/ha for the harvested stand and 12.04kg/ha and 1.26kg/ha for the control stand, respectively. The ratio of N content of foliage to total N content was 58.9% in the harvested stand and 65.3% in the control stand. The ratio of P content of foliage to total P content was 53.0% in the harvested stand and 55.1% in the control stand. LMA was higher in the harvested stand than in the control stand. The LMA of current-year foliage was lower than that of older foliage in both stands. Total chlorophyll and chlorophyll b contents were higher in the control stand. There were no significant differences in chlorophyll a/b ratios between the two stands and between foliage ages. Korean pine seedlings originating from seeds transported by red squirrels showed increased LMA, decreased chlorophyll contents, and increased biomass resulting from improved light conditions following the harvesting of the overstory deciduous forest.