Area surveyed with different sampling rates in the solutions with tree removal and the survey-only problem 1 and 2 solutions.

Colors / shades show the areas surveyed at a particular tree sampling rate and using a particular survey method. X-axis denotes the total budget, $ million, secondary X-axis shows the survey budget portion, $, and Y-axis denotes the survey area, km²: a) surveys based on problem 1 objective; b) surveys based on problem 2 objective; c) surveys in the optimal solution with tree removal.