The area along the length of each branch of a conifer between the trunk to near the end or tip that is green is called the dead zone. It’s not really dead. But there will never be any (or very, very little) new bud growth along that length. If you were to prune a branch in the dead zone, that entire branch will likely die and be ‘isolated’ from the trunk to eventually dry out and break off, leaving a hole.
Some conifers, such as spruce particularly, may form new buds along the length if they are exposed to sufficient sunlight as long as there is even a little terminal bud on the end or tip. These will eventually fill in.
Interestingly, there are deciduous conifers. Deciduous meaning they lose all their leaves every year such as maples, oaks and abuncha other shade trees and conifers, meaning a plant that bears ‘cones’. Larches are one such deciduous conifer. They lose every needle every year.
On the left in the photo below is a weeping European larch losing its needles. Each branch will become totally devoid of leaves (needles) and grow back every year. The Colorado Blue Spruce, on the right, shows the ‘dead zone’ along each branch going into the trunk. I am in the process of pruning that spruce in the Japanese technique of niwaki whereby, eventually, each branch will be bare, exposing the trunk, with ‘clouds’ at the terminus of each branch. Do an image search of niwaki for more info. However, that spruce will develop new buds along each branch that will need to be ‘rubbed off’ each spring. Otherwise, new branches will form.
