Forested Riparian Corridor Restoration

The Mianus River and its tributaries form a riparian corridor that is vital for wildlife and whose health and function contribute to a clean drinking water supply for over one hundred thousand. MRG aims to repair and improve the functional ability of this riparian buffer to filter and prevent water contamination by removing detrimental invasive species and replacing them with native herbaceous plants, shrubs, and trees.

Cited in the 2016 New York State Open Space Conservation Plan, Mianus River Gorge is among the Northeastern Westchester Watershed and Biodiversity Lands identified as a Regional Priority Conservation Project. Additionally, for many years, Mianus River Gorge has worked on creating an open space greenway that stretches from the Mianus River Gorge Preserve in New York State to Cos Cob in Connecticut where the Mianus River empties into Long Island Sound. Designated an official greenway in 2001, the Mianus River Greenway is a riparian corridor whose primary goal is the protection of the water quality of the Mianus River and the preservation of the adjacent uplands.

Mianus River Gorge is working to rid the forested riparian corridor of detrimental invasive species, focusing on a significant segment of the main stem and several key tributaries of the Mianus River within the old-growth forest of Mianus River Gorge Preserve.

Riparian zones are the areas along rivers, streams, lakes, and ponds that form the transitional area between terrestrial and aquatic ecosystems. Riparian zones are important for their ecological function that, generally,

•          contribute rich soils that support more botanical diversity than their adjacent upland areas, supplying food to a variety of wildlife

•          serve as migration routes for animal species as well as provide needed connections between suitable habitats

•          act as filters to reduce nonpoint source pollution and excess nutrients, and settle out sediment from surface runoff

•          slow the speed of flooding waters thereby reducing erosion and the severity of floods

•          help shade rivers and streams, keeping water temperatures down and benefitting sensitive species

•          have deep alluvial soils that store large quantities of water, which slowly seeps out to recharge rivers and streams. During times of high flow, excess water overflows the riparian land to recharge underground aquifers.

•          provide important corridors for the movement of wildlife as they escape climate change.

For riparian areas to provide these valuable functions they must remain healthy. A principle threat to their health is the spread of invasive species of plants and animals that threaten to reduce the unique diversity of these important areas. Mianus River Gorgeis executing a determined, focused effort to remove detrimental invasive species along the main stem of the Mianus River and four major tributaries located within the old-growth forest at the core of Mianus River Gorge Preserve.

Upon completion of efforts to restore and improve the riparian corridor within the old-growth forest, MRG can expand outwards to address the flood plains, meadows, and other habitats within the Mianus River Gorge Preserve and surrounding watershed that impact the quality and quantity of water in the Mianus River.

MRG is working to restore and improve riparian habitat by removing invasive species and replacing them with native herbaceous plants and shrubs, thereby not only protecting drinking water supplies but providing essential habitat and food for native wildlife, including some rarer species that use this corridor for migration like Saw-whet owls, American woodcock, and other songbirds.  Improving the native component of this riparian area increases its ability to buffer against climate change and maintain micro-topography crucial to many of the fragile species found in the Preserve.

The 935-acre Mianus River Gorge comprises an array of habitats, including meadows, flood-plain forest, wetlands, post-agricultural forest, over 100 acres of old-growth forest, and, of course, the Mianus River and its tributaries. Invasive species enter these habitats via several pathways, including waterways. MRG aims to restore the biodiversity and health of several riparian habitats by eliminating detrimental invasive species and replanting with a diversity of native plants to better support pollinators, birds, and other wildlife species.

MRG’s initial target area extends approximately 10 meters on either side of the forested main stem of the Mianus River and a range of approximately 3 – 7 meters on the tributaries. The main stem and each tributary has its own management plan, a derivative of MRG’s overall strategic management plan. The individual plans identify the invasive species present, their corresponding phenology, appropriate method for removal (e.g., physical, mechanical, or chemical), and the native herbaceous plants, shrubs, or trees that are suitable for replanting as they correspond to the habitat’s conditions and / or those species no longer present because they have been extirpated due to deer overbrowsing or other factors. Treating the tributaries and river as vectors for transporting unwelcome seeds and berries prevents infestation on slopes and slides within the old-growth forest.

MRG works closely with the Lower Hudson Partnership in Regional Invasive Species Management and will make an effort to focus on species as categorized into Tiers according to a standard state-wide system, with Tier 1 and Tier 2 species, such as Siebold’s arrowwood, Japanese wisteria, Sapphireberry, and Oriental Photinia, being their priority. MRG will continue efforts to contain and prevent the spread of the invasive species that impact ecological function within Mianus River Gorge Preserve, such as Oriental bittersweet, Porcelain berry, Japanese barberry, and Lesser celandine, to name a few. In addition, MRG generally follows the Vegetation Management / Department of Horticulture Invasive Plant Species Management Guide from Penn State College of Agricultural Sciences in its efforts in invasive species early detection and rapid response at Mianus River Gorge Preserve. “Quick Sheets” help inform our management approaches and adhere to a schedule for recommended treatment.

Healthy riparian zones are crucial to the health of watersheds such as the Mianus River Watershed. Riparian buffers and wetlands help dissipate floodwaters, recharge groundwater supplies, filter out pollution, provide fish and wildlife habitat, and sustain the health of downstream water sources. The healthier the riparian zones, the better job they do at performing these functions. Removing invasive species is an important first step in restoring 90.3 acres within the forested riparian corridor. The community benefits by cleaner, more abundant drinking water resources.

Posted in Announcements, Stewardship & Land Management.