Those trees are excellent, You could make your own deco pack !
BTW. there are options in destructability
You can make them as breakable decos, or use Gopostals destructable brush mod for more control.
Don't worry about making a jungle, I just like to see good use of trees
When it comes to lighting you just need to ask yourself a few questions.
Is it Earth? is it a hot or cold country ? and what time of day is it ?
The first 1 can over-ride the other 2, as your sky-box will be the thing that makes it match.
I can imagine this map with a similar tone to DM-FeelNaPali. Warm and with the sun low, giving orange and yellow colours.
White light often gets criticised, but it does have it's place. Midday somewhere cold, surrounded by white painted buildings (check DM-Kvartal).
Actually 1 map I can see you making a good sequel to (or just finishing) is DM-[ACE]DeadwoodV2. In my opinion great fun (especially team games), but half-made.
Full of neat little touches and details, but you are very aware of being trapped inside a giant box. No effort went into disguising/hiding the edges of the map, but you can have a go on the shooting range, or get buzzed by fireflies in the tall grass.
I put crows and rats in my edit, and added a herd of cows in the fields (they ignore the players unless shot at. Then they stampede).
Oh I also made the fireflies do 1-point of damage if they hit you, and added a buzzing-fly sound, set loud but short-range, so it is like a mosquito buzzing past your ear. Hiding in the long grass now becomes annoying.
1 thing you could experiment with is fog zones depending on the areas you make, but water is a good 1 to play with.
Flowing water is usually clear, but if you have any pools you could add a coloured fog. It can be worth playing with the distance you can see underwater, as it looks dumb when you can see across an entire map underwater.
At the very least remember water is a zone, so it can have it's own lighting and colours.
Actually if you use one of the various particle effects or animated-decos, used to add snow effects, you can add a flow of drifting particles into the water to match the speed of the water texture.