Ground vegetation biomass, production, and efficiency of energy utilization in some northern Wisconsin forest ecosystems

The aboveground biomass of the herb stratum, including woody species up to 30 cm tall, was determined by harvesting annually over a 4—yr period (1969—72) in aspen, maple—aspen—birch, birch, northern hardwood, and logging road communities. Average aboveground biomass in the respective community types was 117.5, 63.0, 51.0, 37.6, and 80.6 g/m2. Root biomass was determined by harvesting the belowground part on selected plots in 1971. Cumulative solar energy received at the sample points was measured with a chemical integrating light meter (petroleum ether chlorophyll extracts). Phenological observations indicated that net annual production in the four forest types was essentially equal to their end—of—season standing crop biomass. Average root:top ratios ranged from 2.98 to 4.79 and were higher in the dry communities (birch and northern hardwood) than in the other more mesic forest. Except for the logging road, two to five species accounted for most of the biomass in each community. Significant positive correlations were found between incident solar energy and aboveground biomass. Efficiency ranged from 0.82% to 2.19% based on May—October cumulative energy in the visible spectrum and cover adjusted aboveground biomass