The tree data frame of an fe_stand object is evaluated in order
to get survey and species specific meta information about these data.
survey_overview(x, tree_filter = TRUE)A data frame (tibble) that gives an overview of the surveys
represented in the input object x. It is basically an evaluation of
the data frame x$trees. It provides information about how many trees
were present in each survey, how many dbh and heights were measured, and
if the dbh and height measurements cover all trees, For dbh this must be
always true, because this is a requirement for a valid
fe_stand object. In addition, we are informed whether a
species that has been documented in the object is represented in a specific
survey or not. As a basis for advanced evaluations, species occurences are
numbered in the columen n_species_occurrence (see Details). In case
an object of class fe_ccircle_spatial_notrees (which is a special
child of fe_stand) is provided as input x, the
function returns an empty data frame.
An object of class fe_stand
A data-masking expression that applies to the
data.frame x$trees. It must return a logical value, and is defined
in terms of the variables in x$trees. In this function, it is used
internally in order to define the cohort of trees which is to be evaluated
by this function (within a call to dplyr::filter()). For this
function, tree_filter should almost never be something else
than TRUE (default)
This function provides meta information that is useful for evaluations that
can be complex on the detail level, e.g. increment calculations from
subsequent surveys. In such contexts, the column n_species_occurence
of the output data frame can be of special interest. If a species is present
for a number of consecutive surveys, all these surveys get the same integer
number in this column. If the same species vanishes, but occurs again later,
the next block of surveys gets the subsequent number, and so on. So, all
consecutive blocks of a species' occurrence are numbered as 1, 2, 3, etc.
At surveys where the species is not present n_species_occurrence has
the value 1.
# Example data: Mixed mountain forest plot with several surveys
mm_forest_1_fe_stand_spatial |> survey_overview()
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