)</p></dd>


<dt>trait</dt>
<dd><p>A data.frame of species traits with a column of species names
matching species names in the community data, and another column with
the trait values.</p></dd>


<dt>FUN</dt>
<dd><p>The function used to aggregate species trait values
in geographic space. By default, if <code>FUN = sum</code>, the sum of
all species traits per area  or grid cell is calculated.</p></dd>


<dt>pol</dt>
<dd><p>a vector polygon of grid cells.</p></dd>


<dt>...</dt>
<dd><p>Further arguments pass