So, will we be seeing the gorgeous colors everywhere in a timely manner this year? What prompts the trees to lose their leaves and why do they change color before they do? Leaves maintain their green hue as long as they are producing chlorophyll, otherwise known as the process of converting sunlight into glucose. As the days get shorter, chlorophyll production slows to a grinding halt – eventually giving way to the ‘true’ color of the leaf. It has to do with the leaf’s pigmentation which gives leaves their familiar green color which comes from that chlorophyll. Remember studying photosynthesis? That is the process that plants use to make sugars from solar energy, carbon dioxide (CO2) and water. Chlorophyll aids in the process of photosynthesis but it is not the only pigment that serves a similar function but other pigments aren’t there in the same concentration as chlorophyll so the more abundant green chlorophyll molecules mask the colors of the other molecules and keep you from seeing them – that is, until autumn rolls around.  

As winter – ie. cold weather -- gets closer, trees pretty much shut down as they become leafless and inactive. Thus, no photosynthesis is taking place so the chlorophyll starts breaking down. When this happens, the green color begins to fade and then you can begin to see the oranges and yellows which have been there all the time but are hidden by the strong green colors. Under optimal conditions, this chlorophyll loss is an orderly process and allows the trees to reabsorb much of the nitrogen in the structure of the pigment molecules.   

There is a bit more going on inside the leaves that only happens in autumn or when it gets cold. In addition to the beautiful bright color pigments -- which are always present but hidden -- the leaves also contain some colors that only show up in autumn. These pigments, called anthocyanins, help plants (trees) recover nutrients from the leaves before they fall off the tree and these are only present just before the leaves drop from the trees. These anthocyanins manifest in red -- and sometimes even purple. Carotenoid pigments are also lost during aging but some are retained which give us our yellow hues. Anthocyanin and chlorophyll together produce brownish colors and anthocyanins and carotenoids together produce orange hues – and thus, you have your rainbow of colors completing the gorgeous scenes we enjoy so much in the autumn. 

 This is Mother Nature’s process: The weather turns cold; the trees prepare to shed their leaves; the amount of pigments in the leaves changes as the leaves prepare to fall. All trees gradually lose chlorophyll during the growing season and this loss accelerates before leaf fall. Anthocyanins increase in concentration and then cease production altogether. And so, the leaves die and fall from the trees.

Here in the White Mountains, the leaves will be changing soon so you need to start thinking about finding some great places to “enjoy the leaves” and there are many places in our area, including the hiking trails written about in other parts of this magazine. So, take some time and enjoy them before they are gone for another year.