1. Urban FIA Sample Design
So lets now talk about the urban sample design using Baltimore MD as an example. This map shows the distribution of core FIA plots across Maryland. One plot per 6,000 acres. The urban sample is obtained by overlaying the US Census Urban spatial layer.

2. Urban FIA Sample Design
Urban forest is within Census-defined urban boundary (UAUC)
Urbanized areas (UA)
>=500 people/mi2,
population >=50,000
Urban clusters (UC)
population 2,500 to 49,999
Here are the 2010 Census Urban Areas overlain.

3. Urban FIA Sample Design
Urban forest is within U.S. Census-defined urban boundary (UAUC)
Constrained by the city’s Core-Based Statistical Area (CBSA).
Then the sampling frame is constrained by the CBSA for the target city. The CBSA includes Carroll, Baltimore Harford, Howard, Anne Arundel, and Queen Anne’s counties. Plots within the Census urban area, constrained by the target city’s CBSA are included in the urban inventory.
(FYI, there are some cases where the target metro area extends beyond the Census Urban Area… for the intensified city sample, the whole metro area (regardless of whether considered Urban by Census) is sampled)

4. Urban FIA Sample Design
Urban forest is within U.S. Census-defined urban boundary (UAUC)
Constrained by the chosen city’s Core-Based Statistical Area (CBSA).
Here is the clipped map-- you can see the core FIA plots that will be a part of our sample.

5. Baltimore, MD Sample
Here is up close All these plots are traditional or core FIA plots. In the core FIA program, tree data is collected only on those plots that have FIA defined forest land. These plots are sampled with the traditional FIA plot design and also with the FIA plot. The plots that are nonforest by FIA definition do not have tree data recorded in the core inventory, but these plots will be visited and sampled using the urban FIA plot design.

6. Baltimore, MD Sample
Now we see the intensification within the Baltimore City boundary. This is a 23x intensification which brings the number of plots in the city up to 206.
Brown boundary = multi-county CBSA
Within CBSA only concerned with plots falling in urban areas/clusters (blue boundary based on Census pop density)
Same sample intensity as base FIA grid; 1 plot/~6000 acres
Within the blue boundary special focus on city of interest (red boundary)…City-based Urban FIA
Intensify red boundary to reach ~200 FIA plots
City intensity based on historic i-Tree sampling for UFORE reporting
City-based Urban FIA annualized to match Rural FIA Cycle
Each CBSA inventory provides for an urban to rural gradient of information
Provides a contextual framework for analyses

7. Urban plot counts by inventory year within Baltimore, MD CBSA
8 plots in Baltimore City are also part of tradition FIA grid
The urban sample for the city of Baltimore, Maryland consists of a 23x intensification of the base FIA sampling frame within the metropolitan area, “red line”, and a base intensity sample within the broader urbanized area, “blue line”. This equates to a total of 98 base intensity sample plots within the urbanized area and 206 base and intensified sample plots within the metropolitan area over the complete cycle. The sample is scheduled on a seven-year cycle length to match the standard FIA sample for Maryland and is augmented by a random 4% re-measurement sample for quality assurance and quality control (QAQC). In the 2014 inventory year this results in two additional QAQC plot visits.
The number of base and intensified plots sampled by inventory year ranges from 34 to 53.
*Base intensity urban FIA plots around Baltimore. These counties have additional, non-urban FIA plots as well
**23X Intensified plots in Baltimore City limits (base FIA+urban only)