The autumnal fall of leaves in deciduous trees is a well recognised event; their changing colours prior to being shed often make for spectacular displays - the New England Fall. Evergreens (with certain exceptions) do not undergo a similar loss of leaves but that is not to say that their leaves are forever green or permanent.  Indeed, each year, evergreens have a seasonal drop of their needle-shaped leaves, it is normal part of the tree’s cycle.  The leaves / needles of conifers have varying life spans; they are not a ‘permanent fixture’.  Many conifer needles will turn yellow then as they age, falling off the tree after one to several years. This change can be gradual or in some species quite rapid.  White Pines (Pinus strobus) typically retain their leaves for 2 to 3 years, whereas Scots Pines (Pinus sylvestris) usually retain their needles for three years. Larches, which are conifers (Larix sp) are somewhat unusual in that they shed their leaves every autumn.  The stress that a tree experiences through drought may result in more rapid browning and greater loss of leaves. Read more...