At nearly 700 acres, Rockland Bog is the largest peatland complex in Mid-Coast Maine. Within 
the town of Rockland, the Bog -- also known as Oyster River Bog -- lies within a relatively undeveloped 
landscape of sparse residential lands to the east and undeveloped lands to the west. It has long been 
recognized as a unique area by local naturalists, and it was the subject of a University of Michigan 
Master's Degree Thesis in 1983 entitled The Oyster River Bog: A Case Study in Wildland Management on 
Private Property. 
The Bog contains several different vegetation types. Based on data collected by University of 
Maine in the 1980s, the largest of these types is a red maple swamp, estimated to cover roughly 30% of 
the wetland -- mostly at the northern end. In descending order of size, the other types are dwarf shrub 
bog, black spruce (Picea mariana) forested bog, sweet gale (Myrica gale) shrub fen, and sedge fen. 
In a 1999 field survey to the site, ecologists noted a beaver lodge, old dams, channeled water, and 
an open water pond created by beaver activity. Characteristic pond species included fragrant water-lily 
(Nymphaea odorata) and cow-lily (Nuphar variegeta). Recent beaver activity appears to have increased 
the area of sedge fen, dominated by slender sedge (Carex lasiocarpa), beaked sedge (C. utriculata), 
silvery sedge (C. canescens), and tussock sedge (Carex stricta). 
Several botanical features are unique to the bog. It contains a small area (a few acres) of plants 
characteristic of plateau bogs --- tufted club-rush (Trichophorum cespitosum) and dwarf huckleberry 
(Gaylussacia dumosa). It also supports a large population of the dragon's mouth orchid (Arethusa 
bulbosa), considered uncommon to rare (but not state-listed) in Maine. 
Rockland Bog MNAP file photo, Lisa Windhausen 

Rare Species/Natural Communities Summary Table: 
Common Name Latin Name State G-S-Habitat 
Status Rank Rank 
Natural Communities 
Unpatterned Fen Ecosystem not S4 
ranked 
Rare Plants 
Moonwort Botrychium lunaria E G5 S1 fields, open woods 
Netted Chain Fern Woodwardia areolata PE G5 SH bogs, acidic wet 
woods 
Other Resources Mapped by MDIFW: 
A Wading Bird and Waterfowl Habitat is mapped within Rockland Bog, and a Deer Wintering Area is 
mapped immediately to the west (see map). 
Conservation Considerations: 
¥ Use of Shoreland Zoning districts vary in each town and may not be in conformance with minimum 
state standards. 
¥ Threats to these systems include hydrologic alteration (from changes in water flow or impoundment 
of waterways), development of adjacent uplands and associated water quality impacts, invasive 
species such as purple loosestrife, and poor timber harvesting practices. 
¥ With regard to timber harvesting, strict adherence to Shoreland Zoning guidelines and Maine Forest 
Service Best Management Practices should help to ensure that the bog remains intact. Ideally, 
however, large areas of the wetland could be set aside in forever wild condition. 
¥ The moonwort occurs in only three other locations in Maine. It was last seen in Rockland Bog in 
1986 but was not re-located in 1999. The netted chain fern was last observed in the area in 1917, and 
it has not been documented anywhere within Maine in the last 20 years. Further surveys should be 
conducted to re-locate both of these species. 
¥ Appropriate conservation strategies include open space tax treatment, conservation easement, and fee 
ownership. 
Protection Status:
The city of Rockland owns over 100 acres within the Bog, and several other tracts are under conservation
easement, including easements from the Center for the Study of Wetlands in Southern Maine.