Maps for Environmentalists

Thursday, August 16, 2012
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meghan maclean in college woods

In College Woods at UNH, graduate student Meghan MacLean stands by a stream that feeds into the Oyster River, which flows into Great Bay, a National Estuarine Research Reserve.

New UNH App Makes Monitoring New Hampshire’s Coastal Watershed Easier.

Graduate student Meghan MacLean’s new software application won’t help you find the nearest barbecue joint. But if you live in New Hampshire’s Coastal Watershed, it will help you understand how your landscape is fragmenting and changing due to development.

Fragmentation of the natural habitat, especially of forests, has adversely affected many parts of the Coastal Watershed. For example, eelgrass meadows, the estuary’s nurseries, diminished by more than 50 percent from 1996 to 2008, according to UNH researcher Fred Short. This is just one indicator of poor water quality, which is generally attributed to the destruction of natural ecosystems through human development. The results of MacLean’s work have produced a better program for mapping forest fragmentation in the Coastal Watershed, created a map of the probability of invasive species presence, and also documented methods that can be used for remotely monitoring the effects of landscape change for years to come.

“Practically speaking, my program, PolyFrag, is a specialized tool for mapping habitat fragmentation. It’s useful for land managers, town planning boards, and organizations such as The Nature Conservancy or the Environmental Protection Agency,” says MacLean, who’s earning her doctorate in natural resources and Earth systems science. “Now areas that might be vulnerable to invasive species can be identified remotely and the advancing of invasive species can possibly be mitigated.”

Within New Hampshire’s Coastal Watershed is Great Bay, a National Estuarine Research Reserve. Six different rivers feed into it. MacLean notes in her dissertation that from 1980 to 2010 there has been a 52 percent growth in population in this region.

Due to development, both of MacLean’s maps – the land cover map and the invasive species or PolyFrag map – represent a lot of fragmentation. On the computer, they both look like very complicated puzzles.

To create an updated land cover map of the region for studying fragmentation and invasive species spread, MacLean used Landsat images of the Coastal Watershed, invasive species data provided by the New Hampshire Nature Conservancy, and did fieldwork.

“Once I had a sampling of ground data, I could perform a classification to turn my Landsat images into a land cover map of the area,” says MacLean. Since Landsat takes a new image of the region every 14 days, for monitoring purposes, the PolyFrag maps can be updated often.

Currently, the most popular program for studying fragmentation is FRAGSTATS, a freely available software program. However, it only performs a statistical analysis in tabular form.

MacLean’s new program, PolyFrag does the same statistical analyses that FRAGSTATS does, but also has excellent visual display capabilities. Additionally, PolyFrag runs as an app within ArcGIS (esri®) software, a geographic information system program used widely throughout the world.

MacLean’s adviser, Russell Congalton, professor of remote sensing and geographic information systems, is editor-in-chief of one of the discipline’s leading journals, Photogrammetic Engineering and Remote Sensing. He also is the director of New Hampshire View (NHView), a website that promotes the use of remotely sensed data, hosted by the University of New Hampshire. ”

MacLean’s program, PolyFrag, will be open source software, available soon on the NHView website.

“I knew I wanted to go open source with this program,” says MacLean. “I like the idea that other people are able to modify the code to suit their purposes. My hope is that people will use it to study their own natural communities.

“The more people we can help, the better!”

Link to Land Cover Map

Land Cover Map of the New Hampshire Coastal Watershed

Using Landsat images of the Coastal Watershed, invasive species data provided by the New Hampshire Nature Conservancy, and fieldwork data, graduate student Meghan MacLean created an updated land cover map. View map.

Link to PolyFrag Map

PolyFrag Prediction Probability Map for the New Hampshire Coastal Watershed

Using PolyFrag, the computer software application that she designed, graduate student Meghan MacLean can translate land cover maps into probability maps that show an area’s vulnerability to invasive species. View map.