Thursday, September 26, 2013

Installing sensors in the New Hampshire Environment

                Sensor & communication technology has advanced rapidly, allowing us to monitor the environment in greater detail than ever before. Yet, there are challenges. Before designing and installing any system, it is necessary to understand the physical environment at each location in detail. The system must be adapted to your specific site and able to withstand the local conditions. For instance, extreme weather associated with hurricane season is a concern in our coastal areas and might be an increasing problem. The goal is to ensure that damage to our sensor networks during these periods is minimal and that we still collect reliable data. It is during these extreme events that we might see some of the most interesting patterns in the data. These and more specific challenges require advanced planning and critical thinking.
Building complex sensor systems takes careful planning and is often a collaborative effort between researchers of different expertise.  Programmers write code to control the actions of the system, technicians install and maintain sensors and loggers, and data managers handle the scores of incoming files. All of this has to be planned ahead of time, so that the end product is something that all stakeholders want to use.
Powering the different systems is another universal challenge. Using solar energy to keep battery banks charged can be difficult in remote forested locations.  Dense cloud cover or thick summer tree canopies limit the incoming solar radiation needed.  To compensate, some systems are overbuilt to ensure it can remain running even during conditions that are not ideal.

Soil Sensors

The soil sensor system is fairly complex and built from scratch, requiring a large amount of work in house before it ever sees the field. When fabricating a system with so many individual parts, system installation can be a challenge. One example of this complexity is how the system samples carbon dioxide (CO2) flux from soil respiration chambers by using two independent control subsystems relying on many different parts to direct flow. One subsystem is pneumatic using a compressor to pressurize a device used to open and shut the chambers. The other uses a pump which pulls samples from the chambers to an analyzer to quantify soil CO2 flux.

  With so many inputs and outputs to the system, tube and wire control can be demanding. For each CO2 sampling chamber there are two sample tubes which carry the CO2 sample to the analyzer and then back to the chamber, two compression tubes which operate the actual opening and shutting of the chambers and four sensors wires used to collect soil data. Keeping things organized and well labeled can be a slow process to ensure that all the different sets get hooked into the right part on the system control side.

Working belowground in the granite state can be difficult when locating areas to install soil sensors and soil chamber foundations.  Probing the ground for suitable locations is a good start but sometimes is misleading with rocks of different sizes.  To determine if a location will work before installing a chamber or starting to dig a sensor pit, first a chamber stencil is used.  This involves drilling out where the chamber support legs will go. If all three legs can be successfully drilled to the proper depth the next step is to cut along the inner edge of the chamber to ensure that the chamber will be able to have a good seal with the soil profile without being offset by rocks. 
Once the chamber is in the ground it is then time to dig a small installation pit on the side of the chamber so the sensors can be installed.  If one side proves to be too rocky then the other side must be tried.  Hopefully we get to the required depth for sensor installation but if not then a suitable location as close to the chamber as possible must be utilized.

Aquatic Sensors

Stream flow in headwater drainages can change dramatically from season to season.  While spring freshets or snowmelt events can be very turbulent, during the summer streams can slow to just a trickle.  Deploying water quality sensors year-round in these headwater streams takes careful consideration.  To sample stream waters properly, the sensors should be located in the active flowing channel to get representative measurements.  However, the channel can be a dangerous place for delicate instruments during storm flow, which can transport sticks, rocks and other debris that can damage equipment.   

Aquatic sensors package ready for deployment

Sensors are deployed in a pool at Saddleback Mountain stream, Deerfield, NH

An effective deployment strategy in this type of site involves mounting sensors to a reinforced cage or crate, which is then secured to the stream bed.  Housings or guards are used to protect the equipment from debris carried at high flow.  This ensures the sensors are secure during extreme events, while still able to be easily removed from the stream to be recalibrated when necessary.  Calibrating simply means to adjust a sensor’s measurements based on how it reads known “standards” for each water quality parameter.  This process is important to ensure the data being collected is reliable, and needs to be done routinely.  Weekly stream water samples are also gathered from sites and run in the laboratory.  Comparing samples analyzed in the lab to the data gathered by the sensors further ensures data quality.

Water quality sensors deployed in winter, safe from ice cover, at Dowst Cate Town Forest, Deerfield, NH.
 Water quality sensor deployments during winter months require additional maintenance during times of extreme cold weather.  It is important that researchers are able to examine seasonal winter patterns in water quality, yet these sensors can be sensitive to the physical damage associated with icing conditions.  When stream pools and runs begin to ice over, technicians need to be aware of these situations to keep the sensors ice-free, or ensure that they are safely below the extent of ice cover.
The EPSCoR sensor network can be considered an outdoor analytical laboratory and as such there are many physical challenges that arise in a variable climate ecosystem like that of New Hampshire.  Careful planning and building is required to ensure the most accurate and reliable data is obtained.  The most difficult places and periods of time can yield some of the most interesting data to study, but require us to think critically about how and when to deploy sensors in these environments.

Posted by Jody Potter, Analytical Instrumentation Scientist III; Brian Godbois, Senior Laboratory Technician; Lisle Snyder, Laboratory Technician II, Natural Resources & the Environment, University of New Hampshire

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

Tuesday, September 3, 2013

Think Like a Fish

On weekend mornings, I often get my fly fishing gear out and with my husband head to a stream nearby.  I live in Concord, NH and I am fortunate that there are so many great fishing streams nearby.  I might head west to fish the Contoocook, north up to the White Mountains to fish the Pemi or the Ammonoosuc, west to fish the Isinglass, or even stay in the “city” and fish the Merrimack, Soucook, or Suncook.  On long weekends, we might head further afield to explore a new stream.  One of my favorite trips was up to the north country last fall to fish the Dead Diamond River.  It was a cold but beautiful day and we didn’t see anyone else, the river was all ours.  We didn’t catch any fish but I really loved that river, the big cobbles and the complexity of the habitat.

 Madeleine fishing on the Dead Diamond River.  Photo credit Neil Olson.
When I was learning to fish I was told to think like a fish and I have taken this advice to heart.  When I am choosing a fly I often say: “Well if I was a fish I would think this looks yummy” or walking up to a new stream I say: “If I was a fish, I would live in that pool under that cut bank, it looks cozy”.  Maybe I was a fish in a past life, I feel very at home in or near water.  I love the white noise of water flowing over rocks which helps to calm my often overactive brain.  I spend a lot of my time in streams because in addition to visiting streams for my hobby, I also work in streams.  I am a stream ecologist and I study water quality. 

Since I enjoy fishing, you might wonder why I don’t study fish but I like having a more holistic view of the whole ecosystem.  A healthy native fish community is a great indicator that the stream ecosystem is healthy.  However, monitoring and understanding water quality allows us to detect disturbances to the stream ecosystem early on and potentially address these issues before negative effects cascade to impact the fish.  

I appreciate the streams and rivers of New Hampshire both as a fisherman and a scientist.  For the ecosystems and society project, I am working on understanding how climate change and land development will affect water quality in our rivers.  These two human disturbances are some of the most serious threats to the health of our rivers and understanding how they will affect water quality is necessary to maintain healthy rivers in NH.  Because whether I’m thinking like a scientist or like a fish, I think good water quality is necessary for our rivers, our fish, and ourselves.

Posted by Madeleine Mineau, Research Scientist, Earth Systems Research Center, University of New Hampshire