State 1
Reference State

Moss cover is very indicative for this site, driving the successional dynamics and species diversity. Sphagnum sp. absorb dissolved mineral cations, and release organic acids, which lowers the pH of stagnant surface water below 5.0 (MN DNR 2003). Sphagnum tends to form carpets of hummocks, which creates an acidic environment cut off from groundwater and on-site ponding. In recently developed bogs, on sites mostly in the western range of the MLRA where soils are less continuously saturated, on sites where water table fluctuations are less variable, or on inclusions of sites where there are upwellings of groundwater, isolated minerotrophic species (i.e. creeping sedge or bluejoint) may be present. Other ground cover includes fine-leaved graminoids, and minimal presence of forbs. Occasionally, seedlings of deciduous tree species associated with adjacent sites (i.e. red maple or paper birch) may become established on Sphagnum hummocks but typically do not survive to become saplings or trees (MN DNR 2003). The overstory usually consists of scattered, stunted (<30ft [10m] tall) black spruce or tamarack (<50% cover) where Sphagum hummocks provide relief from surface flooding (MN DNR Forestry). Most vascular plants associated with Acid Peatlands have a strong association with mycorrhizal fungi, depending on them to obtain minerals and nutrients in this depauperate and harsh environment (MN DNR 2003). These fungi are more diverse on this ecological site than on other sites throughout the region.

Community 1.1
Mature Tamarack-Spruce

This site has a canopy of mature black spruce and/or tamarack. In cases where tamarack is monotypic, it is usually due to a lack of seed source for black spruce, or mortality of black spruce caused by species-specific insects or disease (MN DNR Forestry). Sphagnum dominates the moss layer. The forb layer is often sparse and includes three-leaved false lily of the valley (Maianthemum trifolium), stemless lady slipper (Cypripedium acaule), and Indian pipe (Monotropa uniflora). Both a tall shrub and low shrub layer may occur, but are sparser than less acid peatlands. In cases where tree growth exceeds 50% canopy cover, more shade-tolerant species can be present in the understory, including creeping snowberry (Gaultheria hispidula), soft-leaved sedge (Carex disperma) , ferns (Dryopteris spp.), clubmosses (Lycopodium annotinum), and bunchberry (Cornus canadensis) (MN DNR 2003).

Community 1.2
Spruce Bog

This state is characterized by a canopy dominated by black spruce, although some scattered tamarack may still remain in the overstory. Tree height is generally ranges from 15 - 35 feet (4.5 - 10.5 meters). Graminoid and forb species are usually similar to Community 1.1. Sphagnum has increased and forms large carpets with larger hummocks.

Community 1.3
Poor Fen

This community is characterized by a plant community dominated by sedges or low ericaceous shrubs. An elevated water table inhibits tree dominance. The shrub layer is variable in density and includes broad-leaved evergreens such as bog laurel, leatherleaf, bog rosemary and bog Labrador tea. Moss and liverwort cover is almost always near 100% and composed of Sphagnum species. Oligotrophic Sphagnum species dominant.

Community 1.4
Young Tamarack

This community is dominated by tamarack saplings and young trees and can be present post-logging or large scale disturbance.

Pathway 1.1A
Community 1.1 to 1.2

Lack of fire, accumulation of peat, lowering of pH<5.0

Pathway 1.1B
Community 1.1 to 1.4

Surface fires or windthrow

Pathway 1.2B
Community 1.2 to 1.1

Neutralization of acids on-site raising of pH

Context dependence. Alterations in hydrology which result in the alkalization of bogs, or fire disturbances that can result in mineral inputs from outside sources that offset depletion of cations (especially Ca++) by Sphagnum sp, (even groundwater inputs of <5% of the total water budget relative to precipitation) can revert the process of peat accumulation and acidification, and result in a community type with more minerotrophic

Pathway 1.2A
Community 1.2 to 1.3

Frequent subsurface fires (3-5 yrs) or higher than average precipitation

Context dependence. Pockets of poor fen vegetation can develop in a spruce bog where alkalization of the bog occurs on the lower flanks of the crest, where the water source can receive nutrients from surface runoff, or where the runoff is channeled into drains or water tracks. The transition of the entire site to poor fen can occur on a broader scale when catastrophic fires release nutrients and burn peat, reducing tree cover, reducing evapotranspiration and increasing water-logged conditions, resulting in even minimal groundwater and nutrient inputs to the site. Severe, catastrophic fires can result in conversion of the peatland to an open bog community dominated by fewseed sedge

Pathway 1.3A
Community 1.3 to 1.4

Time, accumulation of peat

Context dependence. This pathway usually occurs naturally with enough time for peat to accumulate and elevate the growing surface out of water-logged conditions, so that tree growth and recruitment can be more successful.

Pathway 1.4A
Community 1.4 to 1.1

Time, accumulation of peat, acidification, establishment and growth of older trees.

Pathway 1.4B
Community 1.4 to 1.3

Severe catastrophic fire or windthrow

State 2
Logged State

This state describes the removal of tamarack and black spruce through logging. The natural plant community has been severely disturbed and the site has been impacted by heavy equipment. Compositional changes in canopy cover and soil/water disturbances impact all layers of the plant community. Best management practices can help reduce site damage and the implementation of post-logging timber stand improvement practices can enhance tree regeneration.

Community 2.1
Logged Community

This state describes the removal of tamarack and black spruce. With the disturbance of the site by heavy equipment. Canopy cover has been removed and shrub density will increase. Species composition will vary depending on the type, timing, and severity of disturbance.

State 3
Invaded State

In this state, invasive species such as Typha sp. or reed canary grass (Phalaris arundinacea) are present. Water ponding for a longer than normal duration results in canopy mortality of tamarack and spruce trees and opening of the understory to light. Alder and willow shrubs often remain on edge zones. Site disturbance such as logging often allows for the introduction of non-native vegetation on these sites.

Community 3.1
Invaded Community

This community is characterized by the presence of invasive plant species. In some areas, ponding has resulted in canopy mortality of tamarack and spruce trees which allows for additional ground level sunlight. Alder and willow shrubs often remain on edge zones. Site disturbance, such as logging, can introduce a variety of non-native species.

State 4
Open State

This state is characterized by sphagnum-dominated acidic peatlands with variable microtopography that includes hummocks, deep hollows, and areas of sphagnum "carpets". This state will exhibit variability in plant community composition due to these variations in microtopography.

Community 4.1
Open Bog Community

Tamarack and black spruce trees are often present but sparse and stunted. Shrub cover is variable depending on the microtopography and may include bog laurel (Kalmia polifolia), leatherleaf (Chamaedaphne calyculata) and bog Labrador tea (Ledum groenlandicum). Moss cover in may be near 100% in some areas. Sedges are common.

Transition T1A
State 1 to 2

This transition involves logging, usually clearcutting, but with reserves for seed sources, site preparation, control for disease and invasive species, and seeding, in order to maintain the site as a viable commercial timber harvesting state. This transition is only possible, or desirable, when the management is applied to phases in which radial growth has been prolific and trees have reached maturity, exhibiting taller, more commercially viable trees.

Transition T1B
State 1 to 3

Impoundment or maintenance of water on-site, and/or establishment of invasive species. Beaver activity, roads, drainage, and other alterations in hydrology can transition the Acid Peatlands out of Reference to an Impounded State, where water is ponded on site for longer durations and receives excessive nutrients from overland surface flow.

Transition T1C
State 1 to 4

Impoundment or maintenance of water on-site. Beaver activity, roads, drainage, and other alterations in hydrology can transition the Acid Peatlands out of Reference to an Open State, where water is on site for longer durations and receives excessive nutrients from overland surface flow causing stunted tree growth.

Transition T2A
State 2 to 3

Introduction and establishment of non-native invasive species.

Restoration pathway R4A
State 4 to 1

Draining or maintenance of water on-site causing alterations in hydrology that can transition the Open state back to the Reference State, where water is on site for shorter durations and receives less nutrients from overland surface flow causing increased tree growth.

Transition T4A
State 4 to 3

Introduction and establishment of non-native invasive species.