Urban Forest Inventory and Analysis in Connecticut
The Waterbury Green. Under the traditional FIA program, trees growing in maintained or developed areas, such as shown, were not recorded. Through the UFIA program, the FIA approach will be expanded into urban areas and trees such as these will be included in the inventory and analysis.
The Urban Forest Inventory and Analysis (UFIA) program is a long-term assessment of trees in urban areas being conducted by the USDA Forest Service. This program is being initiated in Connecticut, with the first data being collected in 2018. Once implemented, the UFIA program will provide information and analyses concerning urban trees that will be of value to all managers of Connecticut's urban forests.
This program is long term - the first set of data for Connecticut will not be completed until 2024. Preliminary results may be released before then.
The Urban Forest Inventory and Analysis (UFIA) program is an expansion of the USDA Forest Service's Forest Inventory and Analysis (FIA) program. The basis of these programs is the inventory of forests, both rural and urban, by means of a point sampling method. These data are then analyzed in a variety of ways. This provides managers, policy-makers and others detailed information about these forests.
The FIA program has been underway in Connecticut since the early 1950's. Over the years, it has produced a great deal of information regarding the state's forests, especially its rural forests. It is because of the FIA program that many of the basic, important facts about Connecticut's forests are known. For instance, foresters know the relative species composition, with red maple as the most common tree, and that Connecticut currently has close to 1.8 million acres of forestland, the equivalent of about 58% of the state.
The Forest Service likes to call the FIA program "the nation's forest census". That is a very apt description for a program that develops detailed forest information on a state by state basis. It also provides a perspective on how these forests are changing over time. Using FIA results, foresters and others can track changes in species composition, forest condition, ownership patterns, pests, and more.
For most of its history, the FIA program has not collected data outside of what it deems as "forest land". The definition of forest land excludes any areas less than an acre in size or 120 feet in width, or land that otherwise has been developed for a non-forest use. Previously, this left out most street trees, any trees on properties in which the understory is mowed, individual trees in parks, and many of the other trees that people interact with on a regular basis.
That changed with the 2014 Farm Bill. Through that legislation, Congress directed the Forest Service to include urban areas in its census of the nation's trees, including those trees that grow outside of the traditional rural forest.
UFIA will collect information on:
Tree Size (diameter and height)
Tree Crown Condition
Urban Tree Utilization and Markets
Ownership and Social Values
UFIA will help us understand what trees species are growing in the urban environment and the relative abundance of these species. Measuring tree size gives managers the ability to assess the benefits these trees provide as well as help them predict the future of the urban forest.
Tree crown condition includes recording the size, shape, and density of a tree’s branches and leaves. This tells a lot about the health of a tree, how well it’s growing in its location, and its impact on plants growing around it. Assessing trees for any signs of damage, such as might be the result of forest pests or disease, storms, environmental stresses, or improper care or management, also provides information about the health of the tree. The likely causes of this damage will also be recorded.
Ground cover is an important component of the urban environment. The UFIA program will record whether the plot area is permeable or impermeable, whether it is lawn, gravel, bare soil, rock, asphalt or cement, whether and what plants are present, and other factors. Many of these factors relate to water infiltration and runoff.
Similar to FIA, on UFIA sites data will be recorded regarding tree characteristics that relate to the potential value of the tree's wood. This includes the same metrics for wood quality, volume and merchantability as are used by more rural forest managers. These will help to inform recognition of the potential for establishing markets for urban wood from trees that need to be removed for any of a number of reasons, including hazard tree removals, storm damage and property development.
UFIA will also provide insight into ownership and social values. The inventory will include classifying land as public or private. Follow-up with property owners will allow a better understanding of the values and perceptions of the urban landowner with respect to his or her trees.
Each plot will be reassessed on a regular, seven year interval. As a result, through the UFIA program, researchers, managers and policy makers will be able to see the changes and trends that are occurring on these assessed plots, and be able to predict patterns on the wider landscape.
UFIA is built off of the FIA structure. FIA is based on a grid of hexagons laid across the landscape, in which one plot is randomly placed within each 6,000 acre cell of the grid. Each plot is, in most cases, one-sixth of an acre in size.
Under FIA, plot locations are mapped across the entire landscape, including in cities, in heavily agricultural areas and in commercial and industrial areas. However, extensive data are only taken for forested plots - those in which forest land is included within the one-sixth acre. On plots that are considered non-forest - such as plots that are largely roads or parking lots, that fall on top of buildings or that are largely water - only minimal data are collected.
The UFIA program is focused on urban centers and their surrounding urban areas. Nationally, UFIA is targeting larger cities, those with a population at least 200,000 in the central city. However, in states that do not have cities that large, one city in that state will be selected. This will typically be that state's largest city.
Describing the plots set up by the UFIA program gets slightly complicated. First, the UFIA program sets up two groups of plots. The first group of plots are 200 plots that are mostly new, not previously established by the FIA program. These are located within the physical border of the central city itself. This creates a group of plots that are likely to be of a greater geographical density than those established through the traditional FIA approach. For instance, in Connecticut, these 200 plots will be placed within the geographic confines of Bridgeport. Since the total area (land plus water) of Bridgeport is 20.4 square miles, this translates to approximately 1 plot for each 65 acres of area in the city.
The second group of plots are outside of the central city proper, in the urban areas that surround the urban center - the city's metro area. The plots in these metro areas will be placed through traditional FIA procedures, with there being one plot per every 6,000 acres. Many of these metro area plots will have been already established, prior to UFIA.
Under the UFIA approach, extensive data will be collected on both the forested plots and non-forested plots. This full collection of data on both types of plots is the key way in which UFIA differs from FIA.
In the field, the non-forested plots and the forested plots are laid out somewhat differently and there are variations in the data collected. However, both plots are designed so that the data and resulting analysis will be compatible and comparable.
In Connecticut, all work in establishing the UFIA plots and in collecting the data will be done under the supervision of the Northern Research Station of the USDA Forest Service. The Forest Service is working closely with the DEEP Division of Forestry.
The UFIA program will be initiated in Connecticut in the summer of 2018. Because sampling the plots selected will involve entering onto the property to where the plot data will be collected, all efforts will be made to contact property owners first. No data will be collected on properties where entry is refused.
Bridgeport, as the state's largest city, is the urban center selected for Connecticut. 200 plots will be assessed in Bridgeport over the next seven years, with approximately 28 or 29 plots sampled each year. At the end of seven years, the cycle will begin again, with the plots originally sampled in the first year being re-sampled in the eighth year. The intention is for this cycle to go on for the foreseeable future, building upon past information as it goes.
Plot centers will be placed based on a randomized grid. As such, these plots will be representative of the landscape of the city. Some of the plot centers will be in water, some on top of buildings, some in parks, and some in the middle of roadways. Their distribution will also be reflective, in geographic terms, of the contribution to the urban forest of the city's various land uses, zoning districts and neighborhoods.
The number of plots, 200, is selected in order to produce statistically reliable results. Each non-forested plot within the city will be established by creating a circle with a radius of 48 feet around the plot center. Any tree greater than 5 inches in diameter at breast height (dbh) that is within that circle will be recorded as to species, height, dbh, crown spread, etc. Smaller plots will be established within this circle, in which data on seedlings and trees less than 5" dbh will be recorded. The type of ground cover (permeable, impermeable, lawn, asphalt, bare earth, etc.) will also be recorded. Forested plots in the city will be measured according to standard FIA protocol.
Data will be collected regarding the surrounding land use - e.g., residential, commercial, etc. - as well as other pertinent information. For each tree greater than 20 feet in height, the direction and distance to any nearby residential buildings will be collected. From this information, a determination can be made about how these trees are influencing energy consumption in those buildings.
In Connecticut as a whole, it just so happens that there are already slightly more than 200 standard FIA plots in the state's urbanized areas. 'Urbanized area' is a term used by the US Census to refer to areas with a population of more than 500 people per square mile that surround an urban center that contains more than 2,500 people. (Map of Connecticut's urbanized areas.)
The US Forest Service recognized this as an opportunity to develop some very useful information for the state, and so agreed to extend the urban area to be sampled around Bridgeport to include all the urbanized areas within the state, not just those in the immediate vicinity of Bridgeport. Because there are 203 FIA established sample points in this larger area, statistically reliable analyses can be generated for this area, in addition to what will be learned specifically about Bridgeport. (Plot map for these urbanized areas.)
The approach to sampling in Connecticut's urbanized areas will be the same as that used in Bridgeport. All non-forested plots in these areas will be sampled, and analyses generated that cover these urbanized areas as a whole.
Similar to FIA, UFIA will, over time, provide reliable information regarding the composition and condition of the urban forest, trends relating to urban tree health and other tree concerns, useful information on the potential utilization of wood from urban trees, details on the benefits provided by these trees, and more.
UFIA is relatively new, so standard reporting formats have not yet been fully developed. Because the data will be made available to a wide audience, it is likely that there will be multiple means developed for the analysis of this data. These, in turn, will almost certainly lead to an equally large number of uses for the results.
One existing tool for analyzing this data has been produced as a cooperative effort between the USDA Forest Service and the Texas A&M Forest Service. Called My City's Trees, this app allows participating cities to upload their UFIA data. The app then uses this data to generate maps, charts and other easily understood summaries of the information gained. (Example of a My City's Trees report)
In Connecticut, data will likely not be made widely available before 2024. That is when the first complete set of data will have been collected and analysis of these data has begun. Preliminary results, however, may be released earlier.
The USDA Forest Service web sites regarding FIA and UFIA are the best places to go to get detailed information on these programs. Please visit the following:
PDF-formatted FIA reports for Connecticut:
Five Year FIA Report - published in 2012 (includes Southern New England)
The USDA Forest Service and others have produced several very good handouts regarding the UFIA program:
UFIA Handout (USDA Forest Service)
UFIA Briefing Paper (USDA Forest Service)
Letter to Property Owners (USDA Forest Service)
UFIA Information Sheet (NA Association of State Foresters)
CT Urbanized Areas (from CT DOT)
Content last updated October 2019