Seeing red.

The color definitely provides the separation I think you were after.  It is so subtle and natural, just like you'd expect.  Nothing ground breaking, but a very solid forest image.  If you could burn just the trunks of the background brightest trees, which could take some time, the separation might even be better.

This image has the same idea as your previous one but is less successful in my opinion. The composition feels busy. The background and tree are somehow at odds with one another instead of complementing. One way to separate would be to darken the background but I don't think that's very realistic. 

This is busy, but I do like the splash of red very much, Ronald. I agree with Gary and Igor's suggestion of selectively darkening areas of the BG to give a little more separation. Nice eye to spot this.

Ed

That's a neat find.  One lone tree struggling to add color to its somewhat monotonous surroundings.  It's doing a nice job. 

I'm wondering about maybe burning down non-red areas just a bit more to make the colorful foliage stand out a bit against the background.
 

I love the complexity of the composition and how it makes me (the viewer) really engage with the presented scene. The red is a strong splash of color which adds to the visual tension. 

I wonder if there was some way to introduce more separation, perhaps via a slightly different orientation of the camera. 

This is a great find in RC, Ronald.  You've done a good job of isolating the red shrub from the surroundings, which is very hard in this heavily forested park.