More RAM will always help and more processor speed as well.
You need to isolate some of the items that are taking the time to rendering. Try rendering just the trees or just the grass... then turn on and off shadows. Minimize the amount of lights in your scene for these tests as well.
Once you find the object(s) that are taking most of the time to render, play with their settings, again with everything else turned off. Trees in the foreground will need the detail, but the trees in the background will NOT need as much detail. I sometimes turn off the shadows for every other tree in my background, not many can tell the difference.
Robert J. Garand
ArchiCAD USA 27-Build 5001 USA FULL
Windows 10 Prof (64 bit) - Intel i9-10920X CPU 3.50 GHz - 128 GB RAM - NVIDIA Quadro RTX 5000