Each tree and stem table is a dataframes that stores data of one census of one plot. That is, for any given plot one tree table stores data recorded during one specific census, and each row records the data from one specific tree. And for any given plot one stem table stores data recorded during one specific census , and each row records the data from one specific stem. For example, if plot X was censused twice, then it has two tree tables and two stem tables.
Each tree or stem table has two remarkable properties:
The number of rows equals the number of trees or stems that were ever found in the plot (in any census). This implies that the number of rows is identical to that of any other tree or stem table of the same plot; also, that trees or stems appear in tree or stem tables before they recruit, while they are alive, and after they die.
The order of the rows is identical to that of any other tree or stem table of the same plot. This implies that you can compare data across censuses even if the row order is important for your analyses. Also, you can easily repeat analyses with different censuses with minimal effort. For example, this structure makes helps to calculate demographic rates between any pair of censuses.
treeID: The unique tree identifier in CTFS database. Useful to be certain
in matching trees.
stemID: The unique stem identifier in CTFS database. Useful to be certain
in matching stems.
tag: Tag number used in the field.
StemTag: Tag number on the individual stem, if present.
sp: The species mnemonic. To get full species names, the taxonomy table
must be downloaded from the CTFS database.
quadrat: Quadrat designation.
gx: The x coordinate within the plot, relative to one edge of the plot.
gy: The y plot coordinate.
MeasureID: An integer automatically generated to uniquely identify a
single DBH measurement. In the future this column may be renamed as
DBHID.
CensusID: An integer automatically generated to uniquely identify a
census.
dbh: Diameter of one stem on the tree, the stem whose stemID is given.
pom: Same as hom but rounded to two decimal places and of type
character.
hom: The height-of-measure, identical to pom but a numeric variable with
full precision.
ExactDate: The date on which a tree was measured.
DFstatus: DFstatus in the R stem file is exactly Status in the
ViewFullTable. Refers to the stem, not the tree -- so in tree tables it is
not useful.
codes: The codes for the measurement as recorded in the field.
countPOM: FIXME
status: The status of each individual stem. In a single tree some stems
may be alive and others may be dead.
A: Alive.
D: Dead.
M: Missing. Case when dbh and codes for a tree was not given, so
it is not certain whether the tree was alive or dead.
P: Prior. It indicates a tree had not yet recruited at this census.
G: Gone. Case when a tree is alive and a stem which formerly had a
measurement does not in this census.
date: The julian date, for date arithmetic.
Compared to stem tables, the the columns of tree tables and mean the same, except when specified below:
status: Indicates the status of the entire tree. For example, if any stem
is alive, the tree is alive; if every stem is dead, the tree is dead:
dbh: Diameter of the tree.
nostems: The number of living stems on the date of measurement.
NOTES:
StemTag is particularly useful for you to know whether the largest
StemTag changed from one census to the other.
DFstatus refers to the status of the stem -- not the tree -- as recorded
in the field (compare to status or Status which is not a direct
observation but calculated from the history of the stem).