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Earth Dr Reese Halter's Blog


Springtime in southern California

Color in the Pacific Northwest forests plays an important role in determining partnerships between plants, animals and insects. As it turns out, plants are masters at manipulating animals and insects, and they do this with their colors.

The predominant color in the forest is green from the pigment chlorophyll, which literally means green leaf. It’s such a dominant color that it masks the beautiful autumn colors of orange and yellow. They belong to a group of pigments called caratenoids, which are loaded with vitamin A. A carrot is an excellent example of this.

In the autumn when deciduous trees begin to draw back some of the nutrients stored in their leaves, chlorophyll breaks down and what is left behind are the golds of birch and oranges of poplar leaves.

The other spectacular fall color are those of the reds, coming from the third group of pigments called anthocyanins. Cool bright weather conditions cause awesome shades of red, most notably on eastern maples. In southern British Columbia and northern Washington where the autumn tends to be a little milder and cloudier, the foliage is a much duller red. However, the drier the autumn the more resplendent the red will be.

It’s the combination of reds, yellows and oranges that also make up the colors of the flowers in Pacific Northwest plants.

Flowers are beautifully colored to attract mainly insects as pollinators (e.g. bees which favor yellows and blues), as well as hummingbirds and bats.

The flowers of Douglas-fir, alder and oak, for instance, are small and not colorful, and they rely upon wind rather than insects as their pollinators.

The colors of berries that are red or black attract some birds to act as seed dispersers. The red berries of the arbutus tree and the black berries of salmonberry are a crucial food source for migrating birds that disperse the seeds, far and wide.

Bright colors draw attention to potential seed dispersers, allow the fruit to be noticed against the green leaves and indicate ripeness of fruit.

Hummingbirds are strongly attracted to red. Bees prefer blue and yellow flowers, They can differentiate shades of white because they can detect UV radiation, which humans cannot (except when we get a sunburn).

Butterflies are attracted to bright blossoms where moths and wasps prefer duller colors. Bats, flies and beetles are not known to have preferential flower colors, rather they rely on other signals like scent to guide them to their hosts.

Color is of paramount importance for pollinating and seed dispersal. And Pacific Northwest plants are able to influence the behavior and movement of animals on which they depend. The exquisite interplay between plants and animals is crucial in the overall health and vitality of our complex forested ecosystems.

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Earth Dr Reese Halter is an award-winning broadcaster and distinguished biologist. His latest books are The Insatiable Bark Beetle and The Incomparable Honeybee

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Text © by Dr Reese Halter 2013. All rights reserved.


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