{"id":34032,"date":"2018-10-19T08:37:35","date_gmt":"2018-10-19T15:37:35","guid":{"rendered":"http:\/\/www.politicsplus.org\/blog\/?p=34032"},"modified":"2018-10-19T08:37:35","modified_gmt":"2018-10-19T15:37:35","slug":"friday-fun-autumn-recycled","status":"publish","type":"post","link":"https:\/\/www.politicsplus.org\/blog\/2018\/10\/19\/friday-fun-autumn-recycled\/","title":{"rendered":"Friday Fun: Autumn Recycled"},"content":{"rendered":"

If you thought (or hoped) I had forgotten my annual treatise on the fantasia of fall \u2013 you\u2019d be WRONG!\u00a0 I\u2019m not going to pass up a review of the wonders of my favorite time of year \u2013 AUTUMN!<\/em><\/strong><\/p>\n

\"\"<\/a><\/p>\n

Road in Vilnius Lithuania<\/strong><\/em><\/p>\n

Let\u2019s start with the science story behind fall\u2019s phantasmagorical foliage fling.<\/p>\n

Once a new leaf is finally fully formed sometime in June, the next thing a tree spends its energy on is preparing the following year\u2019s leaf buds.\u00a0 The job of the leaves currently in place is to create and store food as carbohydrates\/sugars necessary for that new leaf bud.\u00a0 And unlike us, trees are unique in that they\u2019re able to manufacture their own food\/energy, courtesy of photosynthesis<\/strong>.<\/p>\n

\"\"<\/a><\/p>\n

Chlorophyll<\/em><\/strong> is the green pigmented chemical in leaves that uses the energy provided by the sun during the process of photosynthesis<\/em> to convert water taken up by the roots and carbon dioxide taken from the air into sugars and starches \u2013 nutrients that the tree needs for growth \u2013 while giving off oxygen as a by-product.<\/p>\n

But the chlorophyll that gives trees their green of summer is not the only color pigment always present in leaves.\u00a0 Working just as hard in the leaves are the carotenoids<\/em><\/strong> (carotene<\/em><\/strong> and xanthophyll<\/em><\/strong>).\u00a0 These pigments are important in capturing light energy needed in the process of photosynthesis.\u00a0 It\u2019s just that the carotenoids<\/em> are masked by the overpowering green of the chlorophyll during the summer months.<\/p>\n

But with the coming of autumn, as daylight hours shorten and temperatures drop, cells near the juncture of the leaf and its stem start to divide very rapidly.\u00a0 This creates what is called an abscission layer<\/em><\/strong>.\u00a0 This corky abscission layer of cells is the site where the leaf will eventually break from the tree and flutter to the ground.\u00a0 That corky layer then serves to protect the branch through winter after the leaf leaves.<\/p>\n

\"\"<\/a><\/p>\n

Leaf Landing in Lake<\/strong><\/em><\/p>\n

The rapid growth of that corky layer begins to physically block transport of nutrients needed by the leaf to manufacture the carbohydrates.\u00a0 Consequently the photosynthesis that\u2019s been creating chlorophyll (which is not a very stable chemical and has been rapidly breaking down and then replaced throughout the summer) ceases.<\/p>\n

Once the chlorophyll is gone, the carotene and xanthophyll chemical pigments that have been present all summer long now take center stage.<\/p>\n

These carotenoids<\/em><\/strong> (carotene<\/em><\/strong> and xanthophyll<\/em><\/strong>) give their characteristic orange and yellow colors to not just leaves, but also to carrots, corn, canaries, and daffodils \u2013 as well as egg yolks, rutabagas, buttercups, and bananas.\u00a0 And they account as the predominant color in about 15-30% of our tree species \u2013 typically they\u2019re found in the hardwood species of hickories, ash, maple, yellow poplar, aspen, birch, black cherry, sycamore, cottonwood, sassafras, and alder.<\/p>\n

\"\"<\/a><\/p>\n

Look close – there are two girls standing in the Halland Forest, Sweden at the demarcation between the forest and the pines.<\/strong><\/em><\/p>\n

The third class of color chemicals that leaves have (after chlorophyll<\/em> and the carotenoids<\/em>) are the reds and purples of anthocyanin<\/em><\/strong>.\u00a0 But unlike the other two classes, anthocyanin has not<\/u><\/em> been present in the leaves the whole summer.\u00a0 The anthocyanins are created brand new \u2013 just for autumn\u2019s fall foliage!<\/p>\n

Why the tree would expend energy, when it\u2019s shutting down for the winter, for the creation of a new product is not understood.\u00a0 But we do know the brighter the sunlight during this period, the greater the production of anthocyanins \u2013 and the more brilliant the resulting reds and purples. \u00a0This direct proportion of redness to sunlight exposure explains why the periphery of hardwood trees are bright red, while the foliage lower down and inside are the more typical oranges and yellows.<\/p>\n

Anthocyanins also account for the coloring of cranberries, red apples, blueberries, cherries, strawberries, and plums.\u00a0 They are present in only about 10% of hardwood species \u2013 mainly maples, sourwood, sweetgums, dogwoods, tupelos, cherry trees and persimmons.<\/p>\n

But in a few lucky areas \u2014 most famously New England \u2014 up to 70% of tree species are the type that produce the anthocyanin pigment.\u00a0 That high concentration of a single color (the reds of anthocyanin) accounts for the intense but relatively brief autumnal color display in New England.\u00a0 Whereas in most other areas that have a higher mix of tree varieties the colors may not be as intense, but the season lasts longer.<\/p>\n

\"\"<\/a><\/p>\n

Of course, the reds of fall are not only in New England – but all over the world<\/strong><\/em><\/p>\n

You can see where your particularly area is in relation to reaching Peak Color <\/em><\/strong>with this interactive map:<\/p>\n

Fall Foliage Map<\/a><\/p><\/blockquote>\n