Leaves are done in a separate sim. First, I isolated locations of leaf stems, populate the structure with flat boxes, correctly oriented, based on xform matrix of original leafs geometry. Boxes are then simulated as packed RBDs with limited position and rotation constraints, so they don’t move too violently. Some of them could break and fall and are passed into a separate POP sim. After everything was done, I replaced the proxy geo back with the proper leaf meshes.

Pyro

For Pyro dust emission I used multiple sources. Primary these were zones where bigger chunks break apart. If you are using packed RBD sim, you can use Debris Source node as a start, and filter the results more with age, speed or acceleration. Secondary, I emitted from the pop-grains too, again with some appropriate filtering or at least age ramp.

You can further improve the dust emission location with some variation of density by UV noise, REST noise or similar to make it look more natural. Before doing actual Pyro sim, I advise you to cache out any sources to disk. You are probably going to run pyro sim dozens of times before you set it right. No reason to calculate sources each time you do so, just do it once and read from the disk.