Physical comparative tables - guidance notes
The "All Biotopes" worksheet
The "All Biotopes" worksheet shows a summary of the physical
data contained in the core records for each biotope. Biotopes are
shown in rows, with the first four columns containing "header"
information. The first column shows biotope codes, followed in
subsequent columns by the EUNIS level (coloured using the standard
classification colour scheme), the biotope sort order (allowing the
rows to be displayed in the correct classification order), and the
number of core records for each biotope.
The remaining columns, where cells have a white background,
show summary physical information as indicated by the column
headers in the top two rows. Physical factors are split into a
number of categories. For example, "salinity" is split into
"full", "variable" and "low". The categories are equivalent to the
categories used in MNCR field recording, as described
here.
It is possible to filter the data on any of the columns, i.e.
biotope code, EUNIS level, number of core samples, and physical
categories (e.g. it is possible to select all samples that fall
within a particular salinity category).
The figures in the table show the following:
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Salinity
Wave Exposure
Tidal Streams
Height / Depth Band
Biological Subzone
(% Frequency)
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Each of these factors is split into a number of categories.
For each biotope, the figures show the percentage of core biotope
records falling into a given category for a given factor.
Note that these categories are not recorded as percentage
fractions, i.e. a single field record will not be recorded as 50%
full salinity and 50% variable salinity. It either falls within the
full and/or variable salinity category, or it doesn't.
It is possible for a single sample to fall into more than one
category for some of the factors. Conversely, some of the samples
have no data recorded for some of the factors. This means that the
figures will not always add up to 100%.
|
|
Mean Height / Depth
Range
|
These two columns show the mean upper and lower height limit
of biotopes (in metres above / below chart datum).
|
|
Substratum
Inclination
Particle Size Analysis
(Mean Percentages)
|
Again, these physical factors are split into a number of
categories. Unlike the factors above, however, the field records
contain percentage figures for these factors. A single field record
where a particle size analysis was carried out, for example, may
contain 20% gravel, 50% sand and 30% mud. The figures in this table
show the mean percentage value for each category.
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Littoral sediment, Littoral Rock, Infralittoral Rock and
Circalittoral rock worksheets
These worksheets display the same data as the "All Biotopes"
sheet, but with the samples in columns and the physical data in
rows. Because there are more than 256 biotopes, the information
will not fit on a single worksheet, and has therefore been split
into the five broad habitats.
The reason for displaying the data this way around is to allow
easy cross-referencing between biological and physical sets of
comparative tables. By hiding unwanted columns in these worksheets,
it is possible to display any combination of physical biotope
profiles adjacent to each other (provided they are from within the
same broad habitat).
Biotopes which do not appear in the physical comparative
tables
There are a limited number of biotopes that have no core
biotope records. They were included in the classification based on
information from sources other than the JNCC marine database. For
these biotopes, there is no information in the physical (and
biological) comparative tables. In the physical tables, the codes
have been included, highlighted in red. The biotopes which have no
core records are listed above.
Download the comparative tables