This application shows the range of a particular
plant in California as either
a distribution grid:
or as a set of observation points:
To use the application, begin by dragging the
map to an area of interest,
and then zoom in to look at the data in more detail.
After dragging, click on the map
to search for observations in the current map area.
The point where you click is indicated by a red cross
As you zoom in, the size of the grid cells
is set automatically.
The size of a grid cell is reported as, for instance,
15 arc minutes or
1 arc minute.
1 arc minute means that each side of
a cell is 1/60 of a degree in length.
Use the minus and plus buttons to adjust cell size.
When you click on a grid cell, an info window
appears showing how many observations are
within that cell, and offering a link to see the actual
Cells are colored to form a heat map indicating
the density of observations. Cells with one or two
observations are yellow, cells with a medium number
of observations are orange, and cells with
a high number of observations are red.
The heat map coloration is most useful when
zoomed out, as an indication of where a plant has been
Note that the application begins by showing the Terrain map type.
When you want to zoom in closer than the Terrain map type
will allow, switch to the Satellite map type (upper right).
When the application first comes up, it displays a
distribution grid of the whole state,
and reports how many records are available in the map area.
As you zoom into an area of interest, the number of
records reported goes down.
When the number records found in the map area
is 1500 or less,
you can check the Observations radio button
to display individual observations.
(Due to browser memory constraints,
the application can only show 1500 observation points
at a time.)
When you click on an observation point
an info window
appears showing a summary of the observation, and
offering a link to see full details of the observation.
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When you click on this link,
the current state of the page is
added to your browser's URL.
After pressing this link, you can
use the browser to bookmark the URL;
copy the URL and email it to someone; or
use the browser's back button later to return to this state.
See also About Layers.
When you choose a background layer such as Watersheds,
the application will report the
name of the watershed where the center mark
Click on the various watersheds to see their names.
If the Precipitation background layer is showing,
you can click on the map to see average annual precipitation
at that point
Super Planning Watershed:
Tassajara Hot Springs 3309.6003
Line and polygon data is available for certain weeds.
If data is available, a Lines and Polygons
checkbox appears. Check this box, and the
available shapes will be drawn on the map.
Shapes appear as shown on the right.
Note that most lines and polygons are tiny,
so that you must zoom way in to see them.
Switch to the Satellite map type to zoom very close.
To make it easy to find the shapes,
the application indicates
shape observations with this marker:
with this marker: .