Yes, but creating and saving one big object made of all the trees of the level is not very "dynamic"...
Supposing that the trees are all identical (that's the case in the Tank demo), it's probably a better choice to load one mesh (i.e. one tree) and duplicate it to create multiple objects or mutliple limbs. This way, you can change the position of each trees at runtime (to put them on a randomized matrix, for example).
So, the loading time is the same if you use multiple limbs or multiple objects (you only load one mesh).
This makes me think there must be another reason why Lee Bamber used multiple limbs rather than multiple objects.
Anyone's got another explanation ? Or a benchmark, perhaps ?
Ideas: memories of things which did not occur yet...