Physiognomy and Structure: The herb layer is very poorly represented in most parts of this community''s range, contributing only 11% (Ohmann and Ream 1971) of the ground cover in northeastern MN, in contrast with more prominent cover of feather mosses and lichens (35% ground cover) (Grigal and Ohmann 1975).

Floristics: This community is characterized by a pine overstory and a poorly developed understory. Pinus resinosa is present in the canopy at higher cover and basal area than other conifers (typically 80% or more). Pinus strobus can be common in the canopy. Mesic sites tend to include not only Pinus resinosa in the canopy, but also Picea mariana, Picea glauca, and Abies balsamea, whereas on dry sites, Pinus banksiana is found (MNNHP 1993). Beneath the canopy, northern hardwoods, such as Acer rubrum and Betula papyrifera, sometimes form a subcanopy. The understory ranges from moderately herb- and shrub-rich to extremely poor. In the tall-shrub class, the important species are Amelanchier spp. and Corylus cornuta. The short-shrub layer includes Gaultheria procumbens, Linnaea borealis, Vaccinium angustifolium, and Vaccinium myrtilloides, particularly where gaps in the canopy occur (Ohmann and Ream 1971). The herb layer may be moderately closed to sparse, and includes Aralia nudicaulis, Eurybia macrophylla (= Aster macrophyllus), Cornus canadensis, Maianthemum canadense, Pteridium aquilinum, and Trientalis borealis. Mosses can have very high cover and typically include Dicranum spp. (including Dicranum polysetum) and Pleurozium schreberi. The average coverage of feathermoss is greater in the northwest region of Ontario than in the north-central region (Sims et al. 1989). Sims et al. (1989) also found that in the Quetico region of northwestern Ontario, a rich understory of Acer spicatum, Corylus cornuta, Alnus viridis ssp. crispa (= Alnus crispa), Diervilla lonicera, and Aralia nudicaulis was established. Farther north and west, however, the understory was open and dominated by low ericaceous species.

Dynamics:  This is an mid-successional community; however, given the appropriate environmental conditions, it can be extremely long-lasting. Older Pinus resinosa trees have the ability to withstand surface fires due to their thick, corky trunks. Pinus resinosa readily colonizes newly exposed, mineral soils, such as those exposed by a fire, provided older trees have survived the fire as a seed source. Given a surface fire regime of perhaps every 20-30 years and crown fires every 100-150 years, this community may sustain itself for hundreds of years (Heinselman 1973). However, Pinus resinosa is not able to germinate under shade and does not appear to be active in gap phase replacement. Therefore, with fire suppression, this community succeeds towards a canopy that includes other conifers or northern hardwoods.

Fire is an important natural disturbance in this community. Pinus resinosa has adaptations that make it well-suited to frequent surface fires and occasional crown fires. Reconstructions of the fire regime (Heinselman 1973, Frelich 1992) in red and white pine stands indicate that a combination of surface fires every 20-30 years and severe crown fires every 100-150 years maintained presettlement Pinus resinosa communities. The thick, corky bark of older Pinus resinosa make them more resistant to fire than any other type of pine. The stems of older Pinus resinosa are likely to have better survival rates than Pinus strobus and Pinus banksiana when no crown damage results (Ahlgren 1974). In addition Pinus resinosa seedling establishment is favored by exposed mineral soils and high sunlight. Therefore, relatively frequent fires makes the continued regeneration of Pinus resinosa possible, as they are only moderately shade-tolerant. Fire suppression over much of the Pinus resinosa range appears to be leading towards the gradual succession from Pinus resinosa forests to forests of mesic hardwoods or Pinus strobus, species that, with a frequent fire regime, are confined to the understory (MNNHP 1993).