To change the appearance of certain plants (trees, grasses...), you'll need to edit the brf-files. A good editor for .brf-files, is
OpenBRF. I advise you to get the latest version.
Why can't you just remove one of the brfs from the pack and add a native one or another one of your liking? Because of the way the brfs are made. I've put all grasses, trees or snowy trees in their own brfs, but in Native this is not the case. While you can find all the grasses in this mod pack in env_grass.brf, you'll find all the grass in Native in tree_f, tree_meshes.brf, xtree_meshes_b.brf and probably a few others (I didn't check all brfs again). But in these files you'll
also find trees, rocks, skeletons and other objects that are also in my mod pack. So if you enable these Native brfs, you'll get multiple meshes
with the same name. If that's the case, the game loads just the first one that appears in the module.ini, ignores the second one and gives an error (most likely not a crash, but no guarantees there). Since the Floris Mod Pack brfs come at the end of module.ini, the game wil thus load the Native trees and ignore the new ones from this pack. You could of course change the order of files in module.ini, but like I said: I give no guarantees that it won't crash your game.
To get things done properly, we'll need to take the plants from Native (or any other source) and place them in env_grass.brf, while removing the old plant from there. I'm going to show you here how that's done. For this example, I'm going to replace tree_20_a and tree_20_b, from the previous example, by the native ones.
The first thing we need to do, is locate in which brf files those trees are. In the FEMP it's easy: since they are trees, they can be found in env_trees.brf. In native it's a little more difficult to locate: you can find those trees in xtree_meshes_c.brf. Let's move that native brf to our Floris Resource directory before we edit it, so we won't screw up our Native game.
You can click on the picture to get a larger view. Here we see on the left the Native trees we want, and on the right the Polished Landscape trees we don't want. As you can see, the collisions have the same name as the meshes, except for the 'bo_'. This is for easily identifying which mesh and collision are meant to be together. But to be sure, you can always check the text- or source-file.
Also you see that the trees are actually made of two different meshes: tree_20_a and tree_20_a.1. This allows different parts of the tree (the branches, the leaves) to have different textures. We'll obviously need all the different parts to make a whole tree.
We'll delete the trees and their collisions we want to replace in env_trees.brf, so we delete tree_20_a, tree_20_a.1, bo_tree_20_a, tree_20_b, tree_20_b.1 and bo_tree_20_b.
There are two ways we could bring the tree_20's from our Native file to our Floris file:
1) We export each mesh and collision to an object file, and import these object files in env_trees.brf. To export a mesh or collision, right click on the name and select 'Export'. You can export it as an .obj. You can also export multiple meshes as separate files. Once that's done, you can import it in the other brf file by going to 'Import', and select 'Static Mesh'. Now you can import them in the other brf file. It's demonstrated in this picture:
2) Since we copied the Native brf file to our Resource directory and we only need those tree_20 meshes and colisisons, we can also delete the rest. Once that's done, you can go in env_trees to 'Import' and select 'Anything from a BRF'. It's demonstrated in this picture:
No matter what method you used, you'll end up with the right trees in the right file, still having the same name. You've replaced the old trees, but you're not there yet. The tree is too bright and flashy in comparison to the rest of the plants in the game: it will stand out. Luckily this can be adjusted by changing the texture. I've already provided adjusted textures, which you can find in env_materials.brf. You'll need to adjust the textures for both parts of the tree. In our example I change the leaves from 'trees' to 'tr_trees3', and the branches from 'bark' to 'tr_bark_d'
Now you've succesfully transferred the trees into the game. Since they still have the same name, the game will automatically put them in the spot the old trees stood.
I advise you to have at least all the Native names present in your brf file, be it with native, polished landscapes or other meshes. This is especially important for the grasses.