The Washington Post - 20.10.2019

A14 EZ RE THE WASHINGTON POST. SUNDAY, OCTOBER 20, 2019 EZ RE A

Traverse City

Duluth

Missoula

Portland

Bakersfield

Salt Lake City

Denver

Seattle

St. Louis

Nashville

Bloomington

Erie

Charleston

Utica

Charlottesville

Asheville

Atlanta

Miami

Baton Rouge

San Antonio

Fairbanks

Anchorage

Tulsa

New Haven

Burlington

Bangor

New England’s famous

red foliage is thanks to

its maple forests.

Most Northwest forests are

evergreen, but small pockets

of color will occur.

The upper Midwest

features yellow from

beech, birch and aspen

but also has maple mixed in.

Rocky Mountain

aspen is known

for its bright yellow

coloration. In some places,

it can also turn red or orange.

The Smoky Mountains

have a colorful mix of

maple, beech,

birch and oak.

South Texas has oak

and pockets of maple.

Some deciduous trees

will lose their leaves

but are unlikely to

show bright colors.

Alaska’s forests are mostly

evergreen and yellow,

with birch and aspen

changing in the fall.

Forest type and fall foliage colors

Mostly evergreenMostly yellow Mostly red Likely not colorful

200 MILES

200 MILES

BY JOE FOX AND LAUREN TIERNEY

T

his is starting out as a

complicated season for

leaf peepers.

As the East Coast

sweated through rec-

ord October heat, parts of the

Rockies were buried under wildly

early snow. Late heat and early

cold can stifle some of the most

photo-worthy foliage, but soon

enough, large swaths of the coun-

try will be engulfed in the bril-

liant yellows, oranges and reds

that herald an approaching win-

ter. “Leaf peepers” and “color

spotters” will swarm, cameras in

hand, in search of peak fall glory.

Forested areas in the United

States host a variety of tree spe-

cies. The evergreens shed leaves

gradually, as promised in their

name. The leaves of deciduous

varieties change from green to

yellow, orange or red before let-

ting go entirely. Using Agricul-

ture Department forest species

data, we mapped the thickets of

fall colors you may encounter in

the densely wooded parts of the

country.

During the summer, trees pro-

duce chlorophyll, the pigment

that turns leaves green and al-

lows trees to harvest light to

make food sugars. At the same

time, trees manufacture carote-

noid, a yellow to orange pigment

that is masked by the green chlo-

rophyll during the summer

months. When the production of

chlorophyll slows with the onset

of fall, the carotenoid’s bright

color can emerge. This yellow

pigment also helps the leaf ab-

sorb different wavelengths of

li ght that the green chlorophyll

cannot.

Certain species begin to pro-

duce another pigment, anthocya-

nin, when the seasons begin to

change. That i s what turns forests

red and orange. Anthocyanin is

also responsible for the red, pur-

ple, black and blue colors in cer-

tain foods high in antioxidants.

(Think of raspberries, purple cau-

liflower and black rice.) This

crimson pigment allows trees to

continue storing just a little more

sugar and nitrogen to have on

hand for the next year, according

to Paul Schaberg, a research plant

physiologist with the U.S. Forest

Service.

Some areas of the country are

more likely to experience those

bright red and orange leaves than

others. New England is a peren-

nial fall destination because of its

abundance of tree species con-

tributing bright colors.

Schaberg points out that the

best color displays occur in for-

ests that have a diversity of spe-

cies — and trees that have the

tendency to turn red.

The progression of fall creates

a wave of color across the country,

with grassy plains and farmlands

in the Midwest drying up and the

trees of the East Coast rolling

from green to yellow/orange/red

to brown. Descartes Labs collect-

ed and analyzed 10 years of satel-

lite imagery to develop this

cloud-free animation of fall in the

eastern United States.

NASA’s two MODIS satellite

instruments collected all of the

imagery that made the map you

see, taking a picture of every part

of the Lower 48 states twice a day.

This is the equivalent of 500

iPhone snapshots, or 2.2 giga-

bytes of imagery, per day. Des-

cartes Labs experts brought to-

gether all images from 2009 to

2018 to create this composite of

the magic of fall, visible from

space.

Back on Earth, the leaf peepers

prowl different parts of the coun-

try to find their own special spots

for the best fall colors. For Massa-

chusetts resident Jeff “Foliage”

Folger, who runs a New England

fall foliage blog, his annual

photo-foraging is “like a Christ-

mas present. I run around New

England, unwrapping all these

presents,” he said.

Satellite views

In an exploration of fall from

space, Descartes Labs curated

satellite imagery of locations

from Alaska to the southern Unit-

ed States that highlight spectacu-

lar fall colors — both common

and uncommon.

Dazzling colors can be seen in

plenty of regions outside New

England. Wisconsin, Michigan

and M innesota are great places to

go, with forests that blend bright

yellow birch, beech and aspen

with red maple. Farther south, a

mix of oak and hickory forests in

Arkansas provides stunning

Fa ntastic fall foliage — and where to find it

Although many factors influence trees’ fall colors, one of the most important is tree species. This map uses Agriculture Department data to show what colors you might expect across the

country’s forests, based on the species of trees that comprise them. It only includes land classified as forest, so trees in urban parks and backyards are not shown. The colors are a

generalization based on manual classification of each of 141 types of forest, but individual trees in a section of forest shown as yellow can turn red, and vice versa.

views, especially at higher eleva-

tions where there is less develop-

ment.

Even as far south as New Mexi-

co, yellow oaks can be seen on

mountainsides, along with spo-

radic flashes of red maples. Near

Bosque Peak, located in the Man-

zano Mountains just south of Al-

buquerque, bright red foliage can

be seen in the foothills among

dense green forest and brush.

Moving west, yellow domi-

nates. Western U.S. forests are

predominantly evergreen, where

species of juniper, spruce and fir

are better adapted to the more

extreme temperature and mois-

ture shifts. The deciduous trees in

the West, including aspens, tend

to display strong yellows; howev-

er, in some places, such as near

Provo, Utah, the aspens are

known to show red and orange

leaves as well. This could be be-

cause of a few different factors.

Sometimes, carotenoid pigments

can appear orange. (Think of car-

rots.) But all deciduous trees have

the ability to produce anthocya-

nins that create a red color, and

trees that are typically known to

have yellow leaves in the fall can

begin producing anthocyanin if

the trees are experiencing more

stress and find it physiologically

beneficial to produce the pig-

ment.

“There are pockets of beautiful

color all over the West,” says John

Poimiroo, who runs a fall color

blog focused primarily on spot-

ting colors in California, “but

there aren’t a lot of people there.”

So, the majesty can go unseen in

some places.

To find vivid color shows, Poi-

miroo recommends looking in

high-elevation areas in the Sierra

Nevada and near Mount Shasta in

Northern California, where pock-

ets of deciduous trees thrive.

Along Interstate 5 between the

towns of Black Butte and Mount

Shasta, oak trees with orange

leaves and yellow aspen dot the

outskirts of the two towns.

Across Alaska, yellows and

some reds begin to appear as

summer comes to an end, lighting

up mountainsides with bright col-

ors. In the Chugach Mountains

just east of Anchorage, birch and

cottonwood trees, along with low-

lying vegetation, electrify the

slopes. Yellows and oranges also

color the forested spaces through-

out the city, f rom Far North Bicen-

tennial Park all the way to Elmen-

dorf Air Force Base.

The best colors

When it comes to tracking

down those optimal fall colors,

some years can be good, and some

years can be bad. The stochastic,

which is scientist-speak for ran-

dom, nature of when fall colors

occur “makes it a more interest-

ing challenge if you’re trying to do

leaf-peeping,” according to

Schaberg.

Moderate stress, such as chang-

ing seasonal temperatures and

the amount of daylight, helps in-

duce the onset of leaf-color

change, but more severe stress

can mute the vibrancy of au-

tumn’s palette. Drought causes

tree leaves to close up their pores

to retain water, limiting their abil-

ity to produce sugars and leading

the tree to jettison the leaves. To o

much water can promote fungal

pathogens that can infect leaves,

which can also lead to early leaf

drop.

Folger can tick off a few years

that were very disappointing for

fall colors in New England in

particular.

“2005. 2011. 2017,” Folger re-

calls without pause. “It’s almost

cyclic.”

The first two years he cites were

ruined by Hurricanes Katrina and

Irene and the excessive moisture

they brought to New England.

But this season is going to be lit,

both Poimiroo and Folger predict,

on both coasts. Earlier this

month, the Eastern Sierras con-

tinued to turn, followed by color

shows in Northern California,

Southern California and the ur-

ban forests, Poimiroo says. In

New England, low evening tem-

peratures have helped jump-start

the fall colors, according to Fol-

ger. This will eventually wave

down the eastern United States,

down through Appalachia and

beyond.

We wish you luck in your leaf-

peeping endeavors.

[email protected]

[email protected]

Stannard, Vt.

Hardwick

Stannard

Maple, beech and

birch trees glow red,

orange and yellow.

2 MILES

Anchorage

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Birch and cottonwood

trees shine in the

autumn sun

Magazine Mountain, Ark.

Waveland

Magazine

Mountain

Havana

White oak, red oak

and hickory light up

the mountainsides

How fall color spreads across the eastern United States

Sept. 1. Nov. 10

FOREST TYPE DATA FROM NATIONAL FOREST TYPE DATASET. TREE COLOR INFORMATION FROM USDA FACT SHEETS, FIRE EFFECTS INFORMATION SYSTEM, UNIVERSITY OF FLORIDA SOUTHERN TREES FACT SHEETS, UNIVERSITY

OF CONNECTICUT PLANT DATABASE, FOREST SERVICE CLIMATE CHANGE ATLAS AND CALIFORNIA NATIVE PLANT SOCIETY. TREE COLOR MAP HILLSHADE BY RICHARD EDES HARRISON VIA SHADEDRELIEFARCHIVE.COM.

MODIS COMPOSITE IMAGERY OF EASTERN UNITED STATES FALL BY TIM WALLACE AND KRISHNA KARRA OF DESCARTES LABS. DESCARTES LABS CURATED AND PROVIDED IMAGERY FOR LOCAL SITES FROM ESA SENTINEL AND

LANDSAT SATELLITES. 2018 SENTINEL 2 IMAGERY OF ANCHORAGE AND STANNARD, VT. 2001 LANDSAT 7 IMAGERY OF MAGAZINE MOUNTAIN, ARK.