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Distribution maps

Using the distribution maps

Distribution maps are accessed via the maps tab, or directly via https://database.bsbi.org/maps/.

Anyone can access hectad and tetrad distribution maps for all taxa, no login is required.  Maps are updated daily from the live database.  All functionality is available except that:

  • zoom level is restricted to tetrad.  With a login, monad and 100m grid square resolution records are viewable.

  • you cannot search the database by clicking on the map (login required).

  • zoom level is restricted to tetrad, and

  • you cannot search the database by clicking on the map.

Maps appear very quickly, and are first drawn at hectad resolution.  Zooming in using the mouse wheel reveals more detailed resolution records.  By default maps are drawn with the zoom option set to 'zoom to best available' and partition by set to 'date class'.  The screenshot below shows the default options for Adoxa moschatellina, zoomed part way in to show tetrads.

Changing the map options

Options appear for how and what the map displays once you have clicked on Taxon Search and chosen the taxon name you are interested in.

Changing the zoom option to 'zoom to best available (without residue)', hides less detailed records as you zoom in, and provides the clearest mapping.  See the screenshot below, again for Adoxa.

The maps are highly customizable, and the options selected are retained within a single browsing session.

The source can be changed to either records from the live database, or the Atlas 2020 records.

The display can show either presence/absence within a hectad or tetrad, or number of records. If you use number of records, the options under Taxon search are simplified.

The example below show the number of records for Hedera helix at hectad level.

To search at a specified resoluton, change the Zoom option to specified resolution, and change the grid size to hectad or tetrad.

More than one taxon can be mapped. To to this, click on 'add another data series'.  The example below overlays the tetrad distribution of Narthecium ossifragum over the hectad distribution of Tofieldia pusilla.

Changing the display options

You can switch between Map and Satellite views using the buttons at the top left of the screen.

If you click marker styles you can amend the way markers are displayed on the map. If you are displaying presence/absence of records, you can change each date period.

  • stacking order determines which the earliest or most recent records are foregrounded
  • opacity determines how transparent the filled shapes are when overlaid on the map
  • the date range fields allow certain ranges to be hidden/visible, differently coloured, or displayed using different shapes (open or filled squares, circles or trianges, or plusses/crosses)

If you are displaying number of records, you can have a different set of options

  • You can use colour scheme to use a variety of colour series or heatmaps.
  • You can change the marker style to be either square or circle.

The maps tab provides the optimum way to access distribution maps for the whole of GB and Ireland.  If you have a DDb login, similar mapping can be accessed via the ‘search’ tab, but creating maps via searches is much slower, especially for common taxa.  For the commonest species (with >50,000 records in the DDb), the maps tab provides the only route to produce a distribution map.

Using the printable map

First click on the printable map option in the top right hand corner of your screen. This will display a simplified map screen, ready for you to select your printable map options and then print or save the map.

The first set of options to look at is line styles

Here you can select whether you want to display a coastline (and what colour and weight to use)

You can also select whether sea and land display (and in what colour).

By default, an automatic grid is displayed. if you deselect the automatic checkbox, you can then manually determine which type of grid to use, or choose not to display a grid.

The Areas and boundaries panel allows you to filter down by region (British Isles, Britain, Ireland, Channel Islands) and by a wide variety of marked or constrained boundary types.

The page layout panel provides option for changing the display, including the location of the legend box, the title, caption, pagesize, bounday resolution, pixel density, and background colour.

The save or print panel allows the map to be saved as PDF, PNG, SVG, Word document (containing a PNG image) or PDF .