Why is the bottom of my 60ft spruce tree losing all its needles?

The loss of needles at the bottom of your 60ft spruce tree could be due to several factors, including natural aging, insufficient light, or environmental stressors such as drought or soil compaction. It's also possible that the tree is experiencing a pest infestation or disease, such as needle cast. Assessing the tree's overall health and inspecting for signs of pests or diseases can provide more clarity. If the problem persists, consulting an arborist may be beneficial.