Biomass and productivity of the woody strata of forested bogs in northern Minnesota.

The tree stratum was dominated by Picea mariana, and the low shrub stratum by Ledum groenlandicum and Chamaedaphne calyculata. Aboveground living biomass of the tree stratum on 3 perched bogs was declining by 0.5 t ha^-1 yr^-1 from a base of 100.7 t ha^-1, and on 3 raised bogs it was increasing by 0.2 t ha^-1 yr^-1 on a base of 31.0 t ha^-1. Net primary productivity of that stratum was 3.1 and 1.0 t ha^-1 yr^{- 1} on perched and raised bogs, respectively. Low shrub aboveground productivity, equal to mortality, was 0.4 and 2.0 t ha^-1 yr^-1 on perched and raised bogs, respectively, c40% of the standing biomass of shrubs in both bog types. Aboveground net primary productivity of woody strata was 3.5 and 3.0 t ha^-1 yr^-1 on perched and raised bogs, respectively. Data are comparable to earlier estimates of Sphagnum production on the same bogs: 3.8 t ha^-1 yr^-1 on perched bogs and 3.2 t ha^-1 yr^-1 on raised bogs. Vascular herbs contributed an additional 0.2 t ha^-1 yr^-1 to aboveground production on perched bogs and 0.1 t ha^-1 yr^-1 on raised bogs. The higher productivity of perched bogs is probably related to slightly higher nutrient status related to their landscape position. -from Authors