The following additions were made to the *.pov file:

	#version 3.6;
	
	#include "rad_def.inc"
	
	global_settings {
	                max_trace_level 10
	                radiosity {
	                                Rad_Settings(Radiosity_Final, on, off)
	                }
	}
	
	light_source {  // X, Y, Z
	                <-1000, -1500, -1000>
	                color rgb 1.0
	                area_light 200, 200, 10, 10
	                jitter
	}
	
	#declare LDXSkipLight1 = 1;
	#declare LDXSkipLight2 = 1;
	#declare LDXSkipLight3 = 1;

and in the end:

	// Fog
	fog {
	        distance LDXRadius*25
	        color rgb 1
	}

The rendering was done as 1280x1810 (portrait A4 at 155 dpi).

The pdf generated by LPub was postprocessed using:

	pdfcrop --bbox "0 166 596 1008" tree.pdf tree-cropped.pdf

To make it A4 sized.