I have a conifer at the back of my garden which is about twelve years old. It is approx 25 feet tall by 12 feet wide and the house behind us has a higher elevation this conifer has served us well as a privacy shield! Unfortunately I have noticed over the past 18 months or so a gradual thinning of the branches and it is now possible to see through the tree which means loss of privacy. When you stand next to it and look up it looks quite skeletal, the tips of the branches are green but most of the foliage "inside" is brown and lots of the "spines" fall off. A few years ago approx 6 feet was cut off the top, could this be the cause does anyone know?