All pines, spruces, firs, cypresses, cedars and sequoias are evergreen, but that doesn't mean they never drop leaves. They do, all the year round, though there may be some seasonality involved in the amounts they drop and when (I don't know...). A few types of coniferous trees are deciduous, such as larches and the swamp cypress (Taxodium, separate from the true cypresses). Coniferous woodland always has a carpet of leaves (needles) on the ground. When the ground freezes in winter, trees can't take up water and ordinary-type leaves would just dehydrate and die, but needle-type leaves have a tough outer layer and have their stomata enclosed on the inside curve of the needle, which greatly reduces water loss by transpiration. Evergreen broad-leaf trees have various strategies to get them through the winter, such as thick, leathery leaves, sunken stomatas or a covering of dense hairs.