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Yes, in this case it is possible. But not in one step. Well.....actually one step might be possible..... If it can be done with layer blend modes, Lazur might be able to say how. Or I'll bet there's a filter which would do it too. I'd have to experiment myself, to figure out which one. But Lazur can probably say which one to use.
Ok, the one which looks like the best one to me, is Filters menu > Color > Color Shift....
However, it doesn't seem to be exactly what you want. Because for the darker brown colors, they are so dark, that when you change to green, they just still look nearly black. But you can try it, to see what it looks like.
Be sure to select all. Then open the filter dialog and set the Shift slider bar to something around 75, and set Saturation to 100%. It looks like green is anywhere between around 65 to 85 along the Shift bar, and you can experiment about the exact setting. I would leave Saturation at 100%.
Here's how I would do it, without a filter. Everything in the file is colored with gradients. So all you'd have to do is edit the gradients. There are 4 paths in all, which are grouped several times. Here's what I would suggest:
1 - Ctrl A (select all)
2 - Click the Ungroup button (
on the command bar) several times, until the status bar says "No groups to ungroup"
3 - Deselect everything (click on open area of canvas)
4 - Press Tab key once (selects the first object)
5 - Switch to the Gradient tool
6 - Click on one of the gradient stops (which are little circles on each end of the gradient handle, and diamonds in between). Might as well start with one of the end stops (a circle)
7 - Now, when you click on a color in the palette which is just above the status bar, it will change the color for that stop.
8 - Click on the next stop, and change its color, and continue along until you've changed all the stops' colors.
9 - Switch back to Selection tool
10 - Deselect everything
11 - Press the Tab key twice (selects the 2nd object)
12 - Repeat step 5 through 10
13 - Press Tab 3 times to select the 3rd object and 4 times for the 4th, and changing all the stops as you go.
