So you're a devoted psyhead, or maybe even a newcomer to the Psytrance scene, and you've been seeing the term "Forest Psytrance" or "Forest Trance" thrown about amongst the serious freaks, and you have no idea what it means, or what the hell it is.
There's some disagreement over what Forest Psytrance is, or whether it even constitutes a separate genre at all.
Let me lay that to rest right now.
Forest Psytrance is a derivative of Dark Psytrance, that focuses less on high tempos and aggressive distorted electric-sounds and harsh noises and "evil" vocals about death, destruction, nihilism, etc. Use of glitchy, bitcrushed and distorted effects and sounds is less prominent, taking a backseat instead to flanger, phaser, and reverb and delay effects, coupled with dark, deep, pulsing basslines with Lopass Cutoff filters applied to them, to create a warm, murky sound.
Pure Dark Psytrance:
While a form of Dark Psytrance, Forest tends to be a bit slower, between 145-155 BPM, and with a heavier emphasis on atmospheric, moody sounds, and organic textures.
Classic Goa/ Psy Trance "squishy noises" made using sawtooth waveforms and extreme Cutoff Filter settings, and sound samples from nature (bubbling sounds, bird sounds, strange squeaks, blips, whistles, and other "wet" noises are used heavily in Forest to create earthy, organic soundscapes.
Also prominent is the use of atmospheric pads and choirs, usually set to dissonant chord progressions, and with heavy use of phaser, flanger, and reverb effects, to create dark and moody tones that convey a dark, dismal mood (not unlike say, being lost in the woods on a cloudless night).
In summation: Forest Psytrance is Dark Psytrance's nature-loving, tree-hugging kid. Dark and trippy, but less glitchy, and more squishy.
If you want to find more, check out the free Forest releases on Ektoplazm