Fall Foliage - Why do Leaves Change Colour
Nova Scotia is blessed with riotous colour from late September into November, especially where extensive stands of deciduous trees occur as on the hills of the highlands. Salt marshes turn characteristically yellow and orange and blueberry fields and barrens display quilted shades of crimson and vermilion.
During the growing season, leaves of most plants are green, because of the chlorophyll content. Plants are actively using sunlight, water and carbon dioxide to make food, via the absorption of the sun’s energy by chlorophyll. Its characteristic green colour masks the yellows and oranges also present because of the carotene and xanthophyll pigments.
As days become short and the length of night increases, temperatures drop, and the the leaves stop producing chlorophyll. The green colour gives way to the oranges and yellows seen in some species.
Reds and purples arise because of additional chemical changes in the leaves involving the anthocyanin pigment.
Some trees and shrubs turn only yellow, others turn only brown due to varying amounts of pigments present. In addition, there are other changes happening with the leaves. Where the lea and petiole attach to the tree, a special layer of cells develops (the abcission layer). This layer once complete, severs the attachment of stem to twig and the leaves drop, leaving behind a leaf scar. Sometimes a strong wind or rain is required to cause the leaves to fall. Or even the weight of the leaf is enough. Trees like oaks often retain their dried and brown leaves into winter.
Most of the conifers retain their needles or shed a few year-round. However, Nova Scotia’s bogs may be coloured yellow by the presence of larch, or hackmatack. Its needles display golden yellow late into November before dropping, completely denuding the trees.
Did you know? Our weather affects fall foliage colours and duration. Low temperatures, but above freezing favours maples’ reds. If we have an early frost, the reds become muted. Rain and overcast days intensify the foliage colours, but only if there are no high winds. These encourage early leaf drop as does excessively dry summers and fall.
Enjoy the bounty and feel free to share your fall foliage photos with us here.
Point Pleasant Park, by Marian Munro
During the growing season, leaves of most plants are green, because of the chlorophyll content. Plants are actively using sunlight, water and carbon dioxide to make food, via the absorption of the sun’s energy by chlorophyll. Its characteristic green colour masks the yellows and oranges also present because of the carotene and xanthophyll pigments.
As days become short and the length of night increases, temperatures drop, and the the leaves stop producing chlorophyll. The green colour gives way to the oranges and yellows seen in some species.
Reds and purples arise because of additional chemical changes in the leaves involving the anthocyanin pigment.
Some trees and shrubs turn only yellow, others turn only brown due to varying amounts of pigments present. In addition, there are other changes happening with the leaves. Where the lea and petiole attach to the tree, a special layer of cells develops (the abcission layer). This layer once complete, severs the attachment of stem to twig and the leaves drop, leaving behind a leaf scar. Sometimes a strong wind or rain is required to cause the leaves to fall. Or even the weight of the leaf is enough. Trees like oaks often retain their dried and brown leaves into winter.
Most of the conifers retain their needles or shed a few year-round. However, Nova Scotia’s bogs may be coloured yellow by the presence of larch, or hackmatack. Its needles display golden yellow late into November before dropping, completely denuding the trees.
Did you know? Our weather affects fall foliage colours and duration. Low temperatures, but above freezing favours maples’ reds. If we have an early frost, the reds become muted. Rain and overcast days intensify the foliage colours, but only if there are no high winds. These encourage early leaf drop as does excessively dry summers and fall.
Enjoy the bounty and feel free to share your fall foliage photos with us here.
Point Pleasant Park, by Marian Munro
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