Leatherleaf - sheep laurel shrub bog (S2S3)
(formerly leather-leaf - sheep laurel dwarf shrub bog)
Leatherleaf - sheep laurel shrub bogs contain an abundance of dwarf- to medium-height heath shrubs. There are no tall shrubs or trees. Overall species richness is generally quite low. This community is documented from central and southern
Mossy hummock and hollow topography is well developed, with occasional sedges on the hummocks. Average and average-maximum hummock heights measure 0.24 m and 0.40 m, respectively. Average pH is 3.8. Shrubs average 0.52 m in height and form a relatively dense cover (35-50%) compared to other peatland communities. Some examples are extraordinarily acidic (pH in the mid 3s) and have an extremely dwarfed shrub layer less than 6 inches in height. Others are less acidic (pH in the low 4s) and have somewhat taller shrubs, ranging from 1.5 to 2.5 ft. in height.
Characteristic Vegetation: Leatherleaf (Chamaedaphne calyculata) is the dominant shrub, with lesser quantities of sheep laurel (Kalmia angustifolia) and rhodora (Rhododendron canadense). Sphagnum capillifolium is diagnostic and typically occupies hummocks. Other abundant Sphagna include Sphagnum magellanicum and S. rubellum, while S. angustifolium is occasional. Polytrichum strictum is common on hummocks and Billing's sedge (Carex trisperma var. billingsii) is occasional. This community has a higher constancy of S. capillifolium and apparent lower frequency of black spruce (Picea mariana) than leatherleaf - black spruce bog. Nevertheless, scattered individuals of black spruce occur across the larger matrix of vegetation at some sites.
Variants: Two variants are described:
1. Dwarf-medium shrub variant (S3):
Sheep laurel (Kalmia angustifolia), Sphagnum magellanicum, and S. capillifolium are more prominent than in the other variant. Shrub height averages 0.60 m, but occasionally ranges to nearly 1 m. Average pH is 3.8.
2. Dwarf shrub variant (S1):
This variant is floristically similar to the first variant but has a very short dwarf heath layer (shrub heights range from 0.30-0.35 m) and very oligotrophic to possibly ombrogenous conditions. It occupies hydrologically isolated portions of oligotrophic basin peatlands. Vascular species richness is very low compared to most other peatland communities. This variant is superacid, with an average pH of 3.5 (range 3.3-3.7). These pHs are the lowest recorded among lowland peatlands in the state (below 1000 ft.), and they are comparable to or more acidic than those of many alpine bogs. This variant is rare and only occurs at a few sites in the state, including Rochester Heath Bog (
Good examples of this community can be seen at Bradford Bog (Bradford), Rochester Heath Bog (
Leatherleaf - sheep laurel shrub bogs often occur as part of larger poor level fen/bog systems, and sometimes as part of kettle hole bog systems.
Leatherleaf - sheep laurel shrub bog at Ponemah Bog in Amherst (photo by Ben Kimball)