URBAN FOREST DATA GLOSSARY

CARBON STORAGE and SEQUESTRATION

(Found in City UFORE Data Table 17)

Trees moderate the amount of carbon dioxide in the atmosphere through the process of photosynthesis. Carbon that remains locked up in trees from past years is referred to as carbon storage. As trees grow larger each year they sequester additional carbon and add it to the carbon already stored in trunks, branches and leaves. Unlike deciduous trees, evergreens retain their leaves for more than one season, thus adding to their stored carbon. Trees vary significantly in their carbon storage and sequestration rates based on species, size, health, and site conditions.

Net sequestration of a group of trees is equal to gross sequestration minus the estimated carbon released by the decomposition of trees that have died or have been removed.

CONDITION CLASS

(Found in City UFORE Data Tables 11, 12 and 13)

Percent of branch dieback in crown was used as a surrogate measure for tree condition.
E  - Excellent (< 1% dieback)
G - Good (1-10%)
F  - Fair (11-25%)
P  - Poor (26-50%)
C - Critical (51-75%)
D - Dying (76-99%)
K - Dead (100% dieback, no leaves)

MEAN: Weighted average of a species' condition; ranging from 0 (Dead) to 1 (Excellent).

CONTINENT DEFINITION

(Found in City UFORE Data Table 18)

Origin of tree species by continent:
North America+ - North America and any other continent excluding South America
Americas - North and South America
Americas+ - North and South America, and any other continent
Unknown - Mostly hybrids with undetermined origin

DBH or Diameter at Breast Height

Diameter of tree at breast height (4.5 feet or 1.4 meters above the ground) measured on the uphill side of tree. (reported in centimeters for City UFORE Data Tables)

MEASUREMENT UNITS

MBTU - Million British Thermal Units
MWH - Megawatt-hour
t C - Metric ton (tonnes) of Carbon, equal to 2205 pounds (lbs). (Found in CITY UFORE Data Table 15)

SAMPLING TYPE

(Method used to select location of field plots. Found in City UFORE Data Metadata Table.)

Randomized Grid - Cells of equal area are distributed across the study area such that the number of cells is approximately the requested sample size. One plot is randomly located within each cell. If the study is stratified (e.g. by land use type), stratification occurs after plots are selected (post-stratification). This type of plot selection forces the plots to be be geographically spread over the study area and is better for long-term monitoring.

Stratified Random Sample - Study area is pre-stratified to smaller units (e.g. land use types). Sample points are then randomly located within each strata. This type of plot selection will likely produce lower variance vs. random or randomized grid sampling, but is more difficult to use for long-term monitoring because the strata can change over time. Stratified random sampling also allows you to allocate plots to land uses of greater concern.

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