350 instanced BTO trees Giant Sequoia and 350 bushes from the Vegetation set. Material for the terrain from the same set, the terrain from the Gritstone Hill set. Sky and ambient light by the CloudyDaySC HDRI from the HDRI Enhanced Skies set (all available at Daz 3D), the key light by the sun. A cone with Frozencry's Streaming Rays (free here at the Material X-Change) for the sun rays. Everything in a height controlled mirror cube. Experiment with the Bryce Instancing Lab (IL).