Wednesday, September 18, 2013

The Land We Live In: Population, Housing, and Land Use in the Granite State

The birth of a child, moving to a new town, finally buying that summer camp on a lake are happy moments in our individual lives.  But, as of July 2012, the U.S. Census Bureau estimates that there are 1,320,718 people living in New Hampshire – and that translates into many  happy moments.  Over the years and decades, all those happy moments don’t just transform individual lives: they transform communities and the ecosystems we live in.

New housing on cleared woodlands in Seacoast NH. The recent recession slowed housing construction, human migration, and land use change, but as the recession wanes growth is likely to resume. [Photo M. Ducey]

Changes in the size of the population and in the way people live have a significant impact on land use and land cover change.  Although land use and land cover may sound the same, to scientists they describe different things.  For example, if a mature forest is cut down and new trees are planted, there has clearly been land cover change:  the physical and biological character of the land surface have been altered as tall trees have been replaced by a mix of grass, shrub species, and the new trees that will form the next generation of forest.  But the land use has not changed:  the land is still being used to grow trees.  If that same land had been cleared to provide a new shopping mall, then we would say that both land cover and land use have changed.  Every one of us, by living on the planet and making choices about how and where we live, is involved in land use and land cover change.  Humans, it turns out, are a land intensive species and 21st century Americans, especially so.

Number of housing units by Census block from the 2010 U.S. Decennial Census.

Recent changes in housing patterns have tended to spread human impacts over larger areas.  Fewer people per household, bigger houses and lots, and greater ownership of primary and secondary residences have all translated into broader impacts.  A trend that demographers call “selective deconcentration” – the tendency for people to move out of densely packed urban areas as well as remote rural areas, and into suburban areas on the urban fringe or to high-amenity recreational areas – has had a significant impact on both land cover and land use. The recent recession has slowed these migration trends, and it is unclear whether this trend will resume as the recession wanes.  Will higher energy prices and transportation costs, and the growing attractiveness of compact walkable communities, reverse the trend?  Or will flexible telecommuting in an information-based economy and the swelling ranks of baby-boom retirees, only cause it to accelerate?

Percent of houses in each Census block that are second homes.  The U.S. Census counts people at their primary residence, so these second homes are associated with impacts that would not be reflected in population figures alone.

The future course of these selective deconcentration trends has particular relevance to land use and land cover change in New Hampshire. Over the past several decades, New Hampshire has grown from a population of 737,000 in 1970 to 1,320,000 today—a gain of 80% in just 43 years. Much of this growth is the result of people migrating to New Hampshire from other states and of the children these migrants have once they settle in the state. In fact, only one-third of the adults living in New Hampshire were born in the state. Some migrants are attracted to suburban areas of New Hampshire proximate to the Boston metropolitan area. Other migrants, including many older adults, are attracted to the scenic and recreational amenities of New Hampshire’s lakes and mountains. Still other people, who aren’t able to live in the state full time, maintain second homes near the lakes, mountains and forests that have attracted vacationers and seasonal residents to the state for 150 years. All of these demographic forces influence both land cover and landscape change. 

Closeup of the map of total housing density, centered on Lake Winnepesaukee.  The high density of homes along lake shores is clear.  The attraction of high-amenity areas for both primary and secondary homes is an important driver of housing density in New Hampshire, and has consequences for local economies as well as ecosystem services such as water quality and the ability of forests to store carbon.  Developing a holistic picture of those impacts requires integrating data from multiple sources and disciplines.

Stepping back and looking at the long sweep of history, the ebb and flow of human communities and economies has had a profound influence on the New Hampshire we see today.  Only 150 years ago, much of the landscape – including the majority of acres now in forests – was in agriculture.  New Hampshire is currently about 80% forested, and that is probably roughly similar to the percent forest cover that was here when Europeans arrived.  But forest cover is on the decline, mostly due to changes to residential and urban use.  In our research, we seek combine our knowledge of past patterns of forest change with data on demographic change to contribute to a better understanding of future patterns of land scape and land cover change in New Hampshire. What the future holds for New Hampshire depends on the choices its residents, businesses and leaders make today and in the coming years.

Posted by Ken Johnson,Senior Demographer at the Carsey Institute and Sociology Professor and Mark Ducey, Professor of Forest Biometrics and Management, University of New Hampshire


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  2. Great post. I had a great comment that got eaten by the blog site, so this will be a briefer version of my previous attempt to comment!
    Earlier this week I flew from NH to Denver on a clear and cloudless morning. In my window seat, I was struck by the extent of agricultural land use/cover. It was virtually continuous past Vermont and perhaps eastern New York State (minus the great lakes and a couple of urban areas). Now, this is not a surprise to most scientists who study these issues, but it made me reflect on the tremendous extent of human-modified landscapes (agricultural lands in particular) on a national/global scale and the concomitant alteration in ecosystem function. I also reflected on how living in New Hampshire influences perceptions of land cover and land use on a larger scale. We live in the woods and it doesn’t look like the rest of the country!