Modeling wetland plant community dynamics and ecosystem processes with the Mondrian model
Mondrian is a complex process model designed to simulate and explore interactions between plant community dynamics (shifts in species composition) and ecosystem processes in wetlands. We originally designed it to explore the ecology of invasive wetland plants — what plant traits, under what environmental conditions, make them invasive in native wetland communities. But the model has proven to be useful for exploring a wide variety of questions in community and ecosystem ecology as well as applied questions related to wetland restoration.
The graph at right shows results from a simulation using the Mondrian model. In this model result, NPP (net primary productivity, or annual growth) of a native plant population (open symbols) declines as a large-stature invasive plant species (dark symbols) such as cattails or Phragmites invades the wetland and its population has increasing NPP over a period of 10 to 15 years, until it comes to dominate the plant community.
Bill Currie led the development of Mondrian, in collaboration with Deborah Goldberg (University of Michigan), Jason Martina (Texas A&M), and Kenneth Elgersma (University of Northern Iowa).
Futures of Great Lakes watersheds and coastal ecosystems
We recently began a new NASA-funded project, continuing the work with a large collaborative team to link land use, socioeconomic drivers, and climate to the hydrology and water quality in large-river watersheds and the effects on Great Lakes coastal wetlands. In past work, the Michigan team developed the Mondrian model of community-ecosystem processes to better understand the effects of water and nutrient deliveries to the coast on wetland function, including carbon storage, nitrogen retention, and the community ecology of native and invasive wetland plants.
At right: the St. Claire River delta showing wetland plant communities identifed using satellite remote sensing (photo courtesty Laura Chavez at Michigan Tech Research Institute).
In the new project we will link the Mondrian model to the Landscape Hydrologic Model developed at Michigan State University, working with collaborators at MSU. Led by collaborators at Michigan Tech Research Institute (MTRI), the team will use satellite data to extend our modeling across the coastlines of the entire Great Lakes basin. (Other collaborators are at Texas A&M and the University of Northern Iowa.) We will also be extending the coupled models to explore the effects of alternative future scenarios of land use, agriculture, socioeconomic change, and climate change.
Wetland adaptive management and restoration to remove invasive Phragmites
In coastal and inland wetlands throughout the Great Lakes region, the invasive Phragmites plant has come to dominate huge areas, sometimes in patches of multiple km2. In its spread over the last few decades, it has displaced native wetland vegetation along coastlines from Lake Michigan to Lake Ontario on both the US and Canadian sides. While native marsh vegetation is diverse, waist-high and semi-open, stands of invasive Phragmites (common reed) become completely dominated by a single plant species that grows 4 meters high and so dense that light can not penetrate, killing native plants. This significantly alters coastal habitat for birds, amphibians, and fish, which use native marsh to reproduce and to escape predators, allowing fish populations to grow. Phragmites is also a nuisance because it impedes visibility and human use of the shoreline. In a recent conference of Great Lakes mayors of coastal cities, the mayors saw this as one of the premier environmental issues facing their municipalities.
The photograph at right shows field results from our adaptive management project to restore native wetlands (photo courtesy Laura Chavez at Michigan Tech Research Institute).
Together with colleagues at Michigan Tech Research Institute (MTRI), our Mondrian modeling team is working with the Saginaw Bay Cooperative Invasive Species Management Area (CISMA) to develop a framework for adaptive management to remove invasive Phragmites and restore native plant communities. This work has been funded by the Michigan Department of Natural Resources, the University of Michigan Water Center, and the US EPA through the Great Lakes Restoration Initiative (GLRI).
Understanding forest landscapes as coupled human-natural systems in the Great Lakes region
This topic involves a number of ongoing projects with collaborators and students. With Paige Fischer (SEAS, University of Michigan) and her research group, we are working to understand the forest management decision-making of non-industrial private forest owners (or family forest owners) and the effects of those decisions on forest ecosystems and landscapes, including the effects on carbon storage. Private households own the bulk of the private forest land in the “Northwoods” (northern Michigan, Wisconsin, and Minnesota) in parcel sizes of 40 acres and larger. Focus groups being assembled by Dr. Fischer are learning how people who own these family forests make management decisions and how those decisions may be adapting to change, including droughts, forest pests, timber industry changes, and climate change.
At right: Bill Currie and students visit a red pine harvesting operation at Hiawatha National Forest in 2016.
In another project, using spatial datasets that span the entire US portion of the Great Lakes basin, we are using statistical modeling to understand the driving forces that create spatial patterns of forest fragmentation in this region. The patterns of forest fragmentation are driven by the patterns of human settlements and roads together with land use for agriculture. We are studying whether a lengthening growing season for agriculture could potentially drive forest fragmentation further northward.
In other recent activity, Working with Forest Workgroup of the Upper Midwest and Great Lakes Landscape Conservation Cooperative (UMGL-LCC), Bill Currie and colleague Doug Pearsall at The Nature Conservancy recently advised a group of SEAS Master’s students to create an online Story Map of values and threats to the Northwoods.