OK so inporting the data to qgis... here.
The output...
Graduating by colour and size...
To change the scale of the symbol graduation it is necessary to adjust the individual symbol size, adjusting until the relative size is reasonable:
A useful visualization using tree height:
And the dbhs of the same dataset...
Overlaid, the data shows a nice correlation between dbh and height
And now i would like to calculate the individual growing area for each tree...
Vector>Geometry Tools>Voronoi Polygons
This plugin creates a polygon for each tree where the lines are drawn at a distance halfway to each neighbouring tree.
Or we could do a Delaunay triangulation and sum the area of all the triangles touching each tree and compare that...
And then do some kind of statistical analysis verifying whether the "growing area" as defined in these two representations have a significant relationship with the height or dbh... (Or perhaps a shortest line relationship??) Just looking at these representations it seems that dbh has a wider range of values and might be more interesting to work with.
A quick inverse distance wighted interpolation with a a distance coefficient of 4,5 renders the following...
Which is not very informative yet but could probably be done at a higher distance for more conclusive interpolation... But we probably require a larger sample to have environmental factors represented in the interpolation.... And so tomorrow we will be doing an analysis of the areas and tree sizes using R in QGIS via the ManageR interface... here!
Just a quick update...
An interpolation with a distance coefficient of 2 seems more reasonable. It would be interesting to see the soil data for the site.
