Forested Wetlands
The forested wetlands of Indiana are forests that are flooded some or all of the year. This flooding saturates the soil with water and restricts oxygen, creating unique soil conditions for the hydrophytic (water-loving) plants and specially adapted animals that live there. Many reptiles and amphibians, such as snakes, frogs, and salamanders, take advantage of breeding environments in the seasonally flooded areas where fish cannot live. Mammals like beavers (Castor canadensis) are also characteristic of these ecosystems. Typical flora includes trees like bald cypress (Taxodium distichum); black ash (Fraxinus nigra); and larch, which is also called tamarack (Larix laricina). Species of Greatest Conservation Need that use forested wetland habitats include mole salamander (Ambystoma talpoideum) and cinnamon tussock moth (Dasychira cinnamomea).
Areas classified as forested wetland ecosystems in Indiana in 2024.
- Ecosystem Services and Human Benefits
Indiana’s forested wetlands provide natural water management for the state. Water filtered through their vegetation is cleared of chemical and sediment pollutants. Forested wetlands provide rich groundwater for wells and serve as important stormwater flooding reservoirs. They also absorb waterflow from rain or streams, slowing its movement and mitigating or preventing floods and riverbank overflow. Healthy forested areas also act as long-term carbon storage, contributing to cleaner air and a more stable climate. The unique environmental conditions in wetland ecosystems make them vital habitats for plant and wildlife species not found elsewhere.
- Ecosystem Status
Between 2014 and 2024, the area of Indiana’s forested wetland ecosystems declined by 1%. Previous losses were more extensive, with one analysis estimating that nearly 85% of state wetlands have been lost since the 1780s. Although the direct cause of such extensive ecosystem losses is unknown, it is hypothesized that the largest contributors are drainage from tiles and fill surrounding agricultural lands. Across the United States, a majority of the 50 million acres of land using drainage tile occurs in the Midwest, including roughly 4 million acres of Indiana farmland. As agricultural expansion continues, threats to forested wetlands erosion and destruction intensify.
Forested wetlands make up the majority of Indiana wetland ecosystems, encompassing 2.4% of state land cover in 2024. Efforts to expand and preserve this ecosystem have been challenging, with mitigation projects demonstrating a high failure rate. While these projects have resulted in a net gain of overall wetland area, replacement efforts in forested wetlands may be transforming the ecosystem into other wetland types instead of maintaining their natural habitat. While most wetlands do not receive protections under federal law, programs are in action at the state, federal, nonprofit, business, and public level to conserve these important ecosystems. These programs span a wide range of assistance goals, including incentives, education, and land acquisition for increasing forested wetlands protection.
- Ecosystem Pressures
The forested wetlands ecosystem of Indiana is at risk from ecological pressures, including roadside ditching, drainage tiles, and invasive species. As dynamic ecosystems, forested wetlands change over time under natural conditions, with differences in function based on season. Concerns about alterations to natural hydrology around Indiana’s forested wetlands have gained significant attention in recent years. The addition of new roadside ditching and drainage tiles leads to accelerated transportation of surface water to nearby rivers and lakes. This decreases the ability of hydrological systems to tolerate large fluctuations in precipitation and increases the chance of downstream flooding. Tile introduction near forested wetlands also reduces mean wetland depths and significantly shortens surface water inundation periods. Direct impacts are seen on species distribution and abundance as well as ecosystem balance. Similarly, roadside ditching may drain wetlands while simultaneously introducing pollutants from roadway runoff. Water quality is reduced, and habit loss is threatened. Finding ways to manage these tiles will be crucial to reducing natural modifications to forested wetland areas.
Threatened and endangered species within forested wetlands need additional attention as invasive species compete with native populations. Plant species such as reed canarygrass (Phalaris arundinacea), common reed (Phragmites australis), Asian bush honeysuckle (Lonicera spp.), glossy buckthorn (Frangula alnus), garlic mustard (Alliaria petiolata), and oriental bittersweet (Celastrus orbiculatus) use resources and negatively impact wetland water quality. They may shade native plants from sunlight, reducing their growth and survival. Ecological concerns for Indiana’s forested wetlands include terrestrial invasive animal species such as mute swans (Cygnus olor) and feral hogs (Sus scrofa), which may aggressively forage to the detriment of native animals and plants. Forested wetland ecosystems may also be affected by changes in climate patterns discussed in this supplemental report.
Additional pressures affecting forested wetland ecosystems in Indiana can be explored here.
- Ecosystem Conservation Opportunities
Opportunities to conserve key forested wetland ecosystems within Indiana will need to support landowners and conservation groups. Creation and improvement of fiduciary partnerships and outreach and training to support the management and removal of invasive species are examples of such opportunities.
Drainage tile regulations are governed by state law and county boards, with private tile responsibility handed off to landowners. To best support conservation groups and landowners, fiduciary partnerships may be created that allow easier financial distribution for adopting conservation practices. Serving as a link between financial entities and contractors, distribution partners may provide guidance on acquiring financial aid, saving time and money throughout the allocation process. This in turn encourages the use of sustainability practices, as benefits are easier to obtain. Goals of fiduciary partnerships are to increase the resources available and accessed for critical conservation work throughout Indiana.
Managing and removing invasive species is another primary focus of conservation efforts within Indiana forested wetlands. Tackling both private and public land management will be key in reducing the amount of invasive species in the state and preventing further spread of established invasives. Ways to engage with land managers include providing incentives for adopting conservation practices, providing access to hands-on support and training, and discussing the benefits of using conservation practices to maintain the health of Indiana’s ecosystems. Many of DNR’s landholding divisions focus on invasive species prevention and control to foster stable plant and animal communities within forested wetlands. Using these strategies with partnership from private landowners and the public will greatly increase the likelihood of desired outcomes.