Photos of the Long Island Sound

Research & Monitoring

Status and Trends: LISS Environmental Indicators

Land Use Along 300-foot River Corridors in Watershed

% of natural vegetation in 300-foot river corridors by sub-basin

% change in natural vegetation loss in 300-foot river corridors by sub-basin (1985-2010)

change in total area of natural vegetation in 300-foot river corridors by sub-basin (1985-2010)

UConn Clear

natural vegetation consists of forested and wetland land types
 Change in Total Area of Natural Vegetation
NY CT
1985 19,418 575,936
1990 19,266 566,462
1995 19,076 561,548
2002 18,851 555,814
2006 18,766 551,236
2010 18,700 550,791

What is a Riparian Buffer?

Riparian, or streamside, corridors are known to be environmentally important areas critical to stream stability, pollutant removal, and both aquatic and
terrestrial wildlife habitat.  The amount of naturally vegetated (e.g. trees, shrubs, wetlands, and grasslands, but not turf grass or agriculture) land in the zone immediately adjacent to a stream or river is an excellent indicator of how healthy that water body is.  Healthy, fully functioning stream and river systems lead to a healthier Long Island Sound!  This zone (often calculated as either a 100 or 300 foot strip on either side of a stream or river) is also sometimes known as “riparian buffer” areas, since they separate the stream from nearby development. This term should not be confused with regulatory review zones, which are often also called buffers.

What do Riparian Buffers Indicate?

Riparian zones with natural vegetation and soils provide multiple functions and values. They are the first line of defense against the impacts of impervious surfaces (thus the frequent use of the term “buffer”!). Natural riparian areas slow runoff, protect shorelines from erosion, aid in flood control, and filter or trap pollutants. They also provide habitat and migration corridors for wildlife, as well as shade waters for fisheries enhancement. Additionally, intact riparian corridors may provide scenic value and recreational opportunities.

We know that the higher the percentage of naturally vegetated land in this buffer zone is, the healthier the stream or river will be.  A rough rule of thumb is that a river with >90% of the buffer zone vegetated is considered “pristine”, while a river with <75% vegetated buffer is considered “impacted”.  For this analysis, we chose to use satellite-derived land cover data from UCONN’s CLEAR’s Connecticut’s Changing Landscape project, which has created land cover datasets for 1985, 1990, 1995, 2002, 2006, and 2010. For this study, only 1985 and 2010 were used, creating a record of land cover change over the entire 25-year study period. Riparian corridors were characterized for land cover and land cover change within 300 feet to either side of the stream.

Status

Much of the Connecticut and New York portions of the LIS watershed are heavily developed, which negatively impacts riparian corridors, particularly near the coastline.  While riparian corridors in much of the Eastern  and Northwestern portion of the state remain healthy, riparian buffers in most coastal communities are heavily impacted by development.
Furthermore, over the course of the study (1985-2010) riparian corridors are facing an increase in development in virtually every watershed surveyed.  This is particularly true in areas surrounding some of the largest rivers which discharge into LIS (e.g. Connecticut and Housatonic rivers).  Targeted restoration of riparian buffer areas back to naturally vegetated states is needed to preserve and protect the health of these important ecosystems, and of Long Island Sound.

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