They have planted some new trees Pertinax,one can be seen in the very centre of the photo protect by wooden slats. ( And at least one more can be seen just to the left of center )
There used to be quite large trees in at least 2 of the 3 enclosures but the lions seem to have killed them off with a combination of constant scent marking (the 3 prides are rotated periodically so this maybe leads to more of this than normal?) and use as scratch "posts".
I think these enclosures are great,but could maybe do with a bit of freshening up with boulders,trees etc. The staff have been rather busy building new exhibits flat out since these were created in 2009(in the worst winter in living memory round here,with temperatures down to minus 20!)
Maybe when they have finished building the 4 Polar bear enclosures they might "tart" these up a bit. They keep doing little bits to the Amur Leopard and Amur Tiger enclosures to enhance those.