What is going on with all of the White Birches?

Photo credit: Nancy Ritger (9-07)

It looks like a skeleton yard of bleached white bones across the forest. Are all of the white birches dying at once? Is it blight, past evidence of logging or the infamous Ice Storm of ’98?

Well like most things it is a combination of factors. In this case the factors all lead to the same result – a forest highlighting stands of dead white birch trees. First of all, as many readers know, the White Mountain forests have undergone both radical and subtle changes caused by human and natural events. One era that has had lingering effects on our forests is the logging boom of the turn of the century where most every log of marketable size was cut, limbed and railroaded out of here to fuel the industrial revolution. What was seen in its wake was an area, once left untouched for several decades, that was able to rebound to its previous glory, with some changes of course. The most significant changes were the species of trees that grew t

Photo credit: Nancy Ritger (9-07)

o dominate the forest landscape. From historical records we learn that the timber of value was red spruce. What grew in its place were a combination of white birch, maple, cherry and beech depending on elevation. These species are fast growing, short lived and relatively intolerant of shade making up what we call a successional forest. Eventually balsam fir and red spruce also grow up in the forest and begin to compete for sunlight with the faster growing species.

Okay, but why does it appear that all of the birches are dying at once?

Photo credit: Nancy Ritger (9-07)

White birch has a life span of 75-90 years, so the first successional trees after the logging boom are reaching their age limit. Older trees are also more susceptible to environmental stressors such as disease and disturbance. The Ice Storm of ’98 coated trees with an inch layer of ice. The sheer weight of the ice snapped thousand of branches off healthy trees allowing insects and disease a pathway to move in. Now ten years later we can see yet another factor in the white birch story.

So age, disease and damage are all to blame for what looks like a Halloween scene across the forest, but just as we see the skeletons of the white birches, if we look closer we will also see that younger trees are emerging, ready to take its place in the sun and continue the story of human and natural events.

Changes in the Notch

A view of Pinkham Notch as the colors roll down the mountainside. Pictures were taken on September 24 from Square Ledge to the east of Pinkham Notch Visitor Center.



Several pictures taken by Mark Dindorf on the Boott Spur Trail, September 25

The Tundra has Turned

Looking for fall colors? Take a trip to treeline. The tundra plants are actively making the transition, leaving us to marvel at the complicated chemistry and stunningly beautiful results. The sedges and rushes have turned to rich amber as the green chlorophyll breaks down in its narrow leaves.

Anthocyanins, the pigments giving us the reds, are beginning to accumulate in other alpine leaves such as Diapensia that has gone from a tight cushion of tiny green leaves to one of tiny purplish red leaves. The anthocyanin accumulates when sugars produced from photosynthesis in the leaf are unable to be transported to the roots for storage. These sugars attach to otherwise colorless pigments present in the leaf turning them to that unmistakable deep red purple hue.

What is so important about this change of color? The answer lies in the power of the sun and the importance of being ready for the next growing season. On a cool day we all know how nice it feels to sit in the sun. Well if you go put on a dark t-shirt you can absorb even more of the sun’s warmth and if you lie down on the ground out of the wind you might forget entirely how chilled you were a moment ago. Diapensia does just that. By growing low to the ground it is protected from the wind and dark reddish purple hue of the leaves in aids in absorbing the warmth of the sun. This is not so important in the fall and winter when the plant is dormant, but it is essential to the plant in the early spring. On the open windswept ridges where Diapensia grows, the snow depth can be relatively shallow with most of the snow getting blown off into surrounding ravines (hence the awesome skiing later in the spring). Diapensia now deep reddish purple absorbs the warmth of the sun melting it out of the snow earlier than many of the other surrounding plants.

So when you are soaking in those warm rays of sunshine on a cool fall day remember there are a few advantages to thinking about being prepared for spring!

Help us by recording your fall observations! AMC’ Mountain Watch Program is depending on hikers and observers to build our database of changing foliage. By monitoring when the colors change and corresponding weather factors we learn more about the changes in the mountain environment due to climate change. Download your datasheet today.

P.S. I had a recent inquiry about a "friendly" dark gray and white bird found on a hike in the White Mountains. The bird in question is no doubt what we call a Gray Jay, also known as a "Camp Robber or WhiskeyJack". They are known as opportunists, taking advantage of any available food source, including hikers' gorp or trail lunches. There are many popular view points that seem to have their resident gray jays waiting for a scrap. In a few place gray jays have become pesty since hikers are often intrigued by these seemingly tame birds and offer gray jays all sort of M&M's and other treats if they will swoop down and pick it off an outstretched hand. Left to find food on their own gray jays will eat insects and seeds. Birds in this family Corvidae, are known for storing extra food and gray jays have a special gland that produces a sticky salvia which it uses to fasten food items to tree branches, far above any possible snow cover. As year round residents they don't migrate. See "The Sibley Guide to Bird Life and Behavior" by David Sibley for more information.

Photo credits: Mark Dindorf - Southern Presidentials 9/20/07; Nancy Ritger - Lakes of the Clouds 9/17/07

What About the Reds?

The entire landscape shouts of passing time…every turning leaf and bare branch maps the progress of a season and the preparations of whole communities of unseen organisms for a winter many do not know. ~Peter Marchand

As we look across the forest, the greens are slowly giving way to the yellows and oranges, but it is the occasional red tree that really catches our attention. The yellow xanthophylls and orange carotenoids are accessory pigments harvesting a wider range of wavelengths of light than chlorophyll alone. They also serve as antioxidants protecting the chlorophyll from excess sunlight. So as the fragile green chlorophyll breaks down we see the background pigments that are already present in the leaf. But that still doesn’t answer where the red comes from.

Anthocyanins are responsible for the reds, pinks and purples. Anthocyanin is yet another pigment found the leaf. It is colorless until a sugar molecule attaches to its structure. In the fall, sugar created in the leaf during the day through the process of photosynthesis, cannot escape from the leaf at night because chilly temperatures slow down the movement of sap. From the sugars trapped in the leaves, anthocyanin is transformed into brilliant flaming reds or striking purplish hues. We are seeing this transformation in the hobblebush at lower elevations and in the blueberries at higher elevations.

If the leaf contains carotene, as do the leaves of birch, it will change from green to bright yellow as the chlorophyll disappears. In some trees, as the concentration of sugar in the leaf increases, the sugar reacts to form anthocyanins. These pigments cause the yellowing leaves to turn red. Red maples and sumacs produce anthocyanins in abundance and display the brightest reds and purples in the autumn landscape.

The range and intensity of autumn colors is greatly influenced by the weather. Low temperatures destroy chlorophyll, and if they stay above freezing, promote the formation of anthocyanins. Bright sunshine also destroys chlorophyll and enhances anthocyanin production. Dry weather, by increasing sugar concentration in sap, also increases the amount of anthocyanin. So the brightest autumn colors are produced when dry, sunny days are followed by cool, dry nights. If the first few days of September are any indication, we are on the way to a spectacular transformation as we march into the changing season.

If you want to see some early fall colors, venture to the higher elevations where the tundra landscape is beginning to transform. A fall visit to the higher huts is a perfect opportunity to experience the tundra in all its glory- “where every leaf is a flower”. Of course-be prepared for changing weather conditions. And if you are out hiking be sure to participate in AMC's Mountain Watch fall foliage survey.

Photo credits: Mark Dindorf - Speckled Mtn 9/5/07, Nancy Ritger - Square Ledge 9/4/07, Mark Dindorf - Blueberry Ridge Trail 9/5/07, Mark Dindorf - Franconia Ridge 8/31/07.