[R] Using XY location data to calculate ecological parameters

[James R. Milks]

Dear R gurus,

I have XY data giving the locations of tree seedlings that were  
surveyed during a 210 meter belt transect.  This belt transect was  
taken by stretching a line across the field, then measuring all  
seedlings within 1 meter on either side of the line.  The end result  
was XY coordinates and height for ~1,300 seedlings.  I would like to  
use that data to calculate density of seedlings per 10 meters per  
species and relative species abundance in order to compare between  
this transect and other transects as well as to compare between  
segments of the same transect.  Are there any R packages out there  
that will allow me make those calculations?  To give an idea of my  
data, here's a fictional example:

Species				X (m)	Y(m)
Acer negundo		90.10	-.19
Acer negundo		90.14	-.90
Acer saccharinum	90.25	.54
Acer rubrum			90.89	.21
Acer negundo		91.25	.36
Acer negundo		91.46	-.65
etc.

Thanks.

Jim Milks