Marcell Experimental Forest

Climate

The climate at the Marcell is strongly continental, with moist warm summers and relatively dry cold winters with abundant sunshine. Annual precipitation averages 787 mm, and annual temperature is 3.5 °C. About two-thirds of the precipitation occurs as rain, and one-third as snow. Mean monthly precipitation ranges from 25 mm in February to 110 mm in August. Total annual precipitation ranges from 510 to 9,540 mm. Monthly average temperatures in June, July, and August are between 16 and 19 °C, and between -11 and -15 °C in December, January, and February.

Soils

The uplands, lakes and peatlands on the Marcell Experimental Forest formed in ice-block depressions among low-elevation hills that were deposited as glacial moraines and outwash. Shallow post-glacial lakes and ice-block depressions slowly filled with organic soils.

The peatlands at the MEF include fens, poor fens, and bogs. The organic soils in peatlands are typically less than 3 m deep in glacial lake beds but may exceed 10 m in ice-block depressions. Forested fen peatlands developed on woody and Sphagnum peat (Mooselake Series, Euic, frigid Typic Haplohemists). They are typically hemic in decomposition, reddish, and full of wood fragments. The forested bog peatlands developed on Sphagnum peat and are more highly decomposed sapric peats (Loxley Series, Dysic, frigid Typic Haplosaprists).

Glacial drifts are 45–55 m thick and form a regional groundwater aquifer above pre-Cambrian Ely greenstone and Canadian Shield granite and gneiss bedrock.  Upland soils are derived from outwash sands on about one-third of MEF and include Menahga sands (Mixed frigid, Typic Udipsamments), Graycalm loamy sands (Isotic, frigid, lamellic Udipsamments), Cutaway loamy sands (Loamy, mixed, superactive, frigid Arenic Oxyaquic Hapludalfs), and Sandwick loamy sands (Loamy, mixed, superactive, frigid Arenic Glossaqualf). On the remaining two-thirds of the MEF, the sandy outwash is covered by a clay loam till that contains fragments of limestone and shale. These soils are Warba very fine sandy loam (Fine loamy, mixed, superactive, frigid Haplic Glossudalfs), Nashwauk loam (Fine-loamy, mixed, superactive, frigid Oxyaquic Glossudalfs), and Keewatin loam (Fine-loamy, mixed, superactive, frigid Aquic Glossudalfs). Upland soils tend to be covered by upwards of 10 cm of loess. 

Invasive nonnative earthworms have been observed in upland soils throughout the MEF since the 1970s, likely affecting the thickness of the O and A horizons.

Vegetation

In the Marcell, sandy uplands support red and jack pine in fire-origin stands or in plantations, along with mixed stands of aspen, white birch, balsam fir, white spruce, red maple, and red oak. The sandy loam till soils support similar mixed stands. Forested bogs contain black spruce and tamarack. The peatland surface is dominated by Sphagnum mosses and ericaceous shrubs. The forested fens contain similar species as the bogs but also black ash. Open, poor fens are dominated by depauperate sedges and a variety of mosses.

The Marcell Research Center opened in 2006 as the headquarters of research and has bunkrooms, office, preparatory laboratory, kitchen, laundry, bathrooms, and conference/meeting room.

Lat. 47°32′ N, long. 93°28′ W

Research, Past and Present

The Marcell Experimental Forest (MEF) is one of the longest running peatland research programs in the world, with data collection starting as early as 1960 and continuing to expand through present. At the time of establishment, most USDA Forest Service watershed studies were established in mountain ecosystems; adding the MEF thereby expanded the scope of Forest Service watershed studies.

Observational and experimental research at the MEF has been fundamental in developing knowledge of peatland ecology, hydrology, and nutrient cycling from peatlands (both bogs, fens) and uplands. Specific areas of research at the MEF include watershed hydrology, atmospheric deposition, nutrient cycling, organic soil properties and hydrology, aquatic invertebrate ecology, and tree-stand dynamics, with a particular focus on peatlands.

Six research watersheds at the MEF have been used in assessments of the effects of land management and environmental change on forests, water resources, and nutrient cycling. Each of four experimental watersheds is paired with one of two reference watersheds. At the core of the program is long-term environmental monitoring of water budget and energy balance components, meteorology, chemistry, atmospheric deposition, soil properties, vegetation biomass, and trace gas emissions. 

Major Research Efforts and Accomplishments

Management, watershed, and environmental change studies include:

• Clearcutting of upland and peatland forests with natural regeneration
• Clearcutting and conversion of an upland forest from deciduous to coniferous cover
• Conifer strip cutting in a peatland
• Revegetation of a fen following harvest
• Upland forest nitrogen fertilization
• Climate change (i.e., warming and carbon dioxide increases)
• Peatland drainage
• Effects of atmospheric pollutants (e.g., mercury, sulfate) on peatland element cycles

Plot, mesocosm, and hillslope studies have been used to study:

• Stemflow and throughfall
• Soil frost formation and persistence
• Carbon storage and cycling
• Trace gas emissions from uplands and peatlands
• Wood decomposition
• Mercury transport, cycling, and bioaccumulation
• Forest harvesting effects on forest and soil productivity

The first decade of research at the MEF led to refinements in basic understanding of how hydrology and soils vary between peatland types (bogs and fens) and to fundamental progress in quantifying physical and hydraulic properties of deep organic soils. With the implementation of watershed experiments, the late 1960s and early 1970s marked the beginning of research to quantify the duration and magnitude of forest harvesting effects on water availability, chemistry, and hydrological response to disturbances.

By the late 1970s and the 1980s, watershed research expanded to include mechanistic studies of water and solute transport through watersheds, including water and solute budgets and initial studies of carbon, nitrogen, and sulfur cycling in peatlands. 

The MEF also figures prominently in the establishment of national programs to measure the effects of atmospheric pollutants on rain and snow chemistry. The MEF has the longest running National Atmospheric Deposition Program (NADP) National Trends Network (NTN) site (MN16), established in 1978. The MEF is also a founding site in the NADP Mercury Deposition Network, with records back to 1996.

The MEF gained renown for pioneering studies of natural methane emissions from peatlands from the 1980s to 1990s and implementing the first year-round measurements of peatland methane emissions. The first use of the eddy covariance technique to measure net ecosystem exchange of carbon in a peatland also occurred at the MEF. Expanding on earlier studies, carbon dioxide and methane fluxes measurements were reinstituted during 2007 and have continued uninterrupted since then at the MEF’s Bog Lake Peatland, which is part of the AmeriFlux program (site US-MBP) and one of longest running studies of net carbon exchange in a peatland.

Novel studies of environmental mercury pollution also began in the 1990s and have been a hallmark of the research program since then.  The earliest mercury studies focused on mercury in stemflow, throughfall, and stream waters, which provided evidence of when and how much mercury entered and left the ecosystem. Later studies were focused on deciphering pathways of mercury transport through upland soils and peatlands, quantifying methylation rates, and assessing bioaccumulation as well as experiments to assess effects of sulfate deposition on methylmercury production in peatlands and downstream movement. Now, the record of total and methylmercury concentrations in stream waters exceeds two decades and provides an unprecedented record of how cleaner emissions contribute to reduction of toxic methylmercury in headwaters with peatlands. 

As a result of decades of peatland research at MEF, it was chosen by the US Department of Energy (DOE) to host the most expansive climate change research manipulation on the planet, the Spruce and Peatland Responses Under Changing Environments (SPRUCE) experiment.  Since 2009, the DOE and their Oak Ridge National Research Laboratory in Tennessee have partnered with the NRS to establish a massive SPRUCE experiment to assessment the impact of both above- and belowground warming and elevated carbon dioxide in a bog at MEF for 10 years starting in 2016.

For its substantial contributions to research on peatland ecohydrology and biogeochemistry, the Marcell Experimental Forest was designated as Wetland of Distinction by the Society of Wetland Scientists in 2023.

We continue to study the long-term impacts within watershed and plot-level studies as well new innovative research on the effects of climate and other changes on ecosystem processes.

Research Opportunities

The depth and breadth of existing datasets at the MEF afford graduate students and collaborating scientists a unique opportunity to study upland and peatland systems in the northern Lake States region.

Forest Service researchers at the MEF embrace collaborative research and welcome engagement. 

Long-term monitoring and datasets at the MEF include:

• Streamflow
• Precipitation amount and chemistry
• Net radiation, incoming and outgoing radiation, and photosynthetically active radiation
• Soil moisture
• Surface water, groundwater, and soil porewater chemistry and water isotopic relative abundances
• Snow depth, frost depth, and snow water equivalent
• Air and soil temperature
• Relative humidity
• Upland runoff volume and chemistry
• Carbon dioxide and methane fluxes

Click here to access data from the Marcell Experimental Forest