The epidermis has a thick cuticle and stomata are sunken. Xero means dry. These adaptations help to explain why conifers can survive harsh winter and summer conditions. A great deal of energy is invested in leaf production. Consequently, it is more efficient for leaves to function over several years.
Conifers do shed their leaves but most do so gradually over a long time span.
New leaves appear as old ones are shed. Thus, it appears that the plants never shed their leaves. However, a stroll through a conifer-dominated forest will quickly dispel this notion. Pine needles are allelopathic and kill understory plants. Consequently, these are not the best plants to use for erosion control.