Bios 
Pin Cherry Perceptions 
The language we use in our investigations of nature affects 
the questions we ask and the answers we get 
by Robert E. Cook 
In late April and May, when birches 
turn New England’s hillsides pale green 
and swamps grow pink with red-maple 
buds, the blossoms of pin cherry burst 
out in an umbrella of white-petaled flow- 
ers surrounded by a haze of honeybees. 
The rise of sap from the cherry’s roots 
brings a reddish hue to the shiny black 
bark with its horizontal gray lenticels. 
The pin cherries are soon lost in the 
foliage of the summer forest, but they 
become prominent again in August 
when the ripening fruits draw late-nest- 
ing waxwings and flocks of migrating 
robins to harvest strings of cherries. 
Without much delay the birds process 
the sweet pulp and pass the stony seeds 
on to the forest floor. 
Conspicuous members of the north- 
ern hardwood forests of the Northeast, 
pin cherries ( Prunus pensylvanica) 
never grow very old, seldom living be- 
yond thirty years in the forest. The biol- 
ogy of this short-lived species seems 
designed to rapidly produce a large 
number of single-seeded drupes, fleshy 
fruits with an inner stone that holds the 
seed. A young pin cherry may first show 
flowers only four years after germina- 
tion, when it is barely a sapling. Peak 
yields occur between the ages of fifteen 
and twenty-five, and over its entire life, 
a healthy, free-growing female may 
form more than 32,000 drupes. 
The fruiting pin cherries are often 
found thriving on land that has recently 
seen disturbance or destruction of the 
vegetation: about the edges of breaks 
and trails or scattered among the young 
oaks, beeches, and sugar maples that 
revegetate cutover land. The species is 
sometimes called fire cherry because its 
seedlings quickly occupy burned-over 
forests, where they may form a single 
stand of rapidly growing foliage. It also 
follows promptly in the wake of loggers, 
emerging through the piles of slash and 
raw stumpage within a year or two of 
the cut. As salvager of ravaged land- 
scapes, the pin cherry has recently cap- 
tured the attention of ecologists investi- 
gating the recover)' of damaged eco- 
systems. 
By the middle sixties, the growing 
alarm among environmentalists con- 
cerning the devastating impact of some 
human activities on wilderness areas 
had thrown the wisdom of forest clear- 
cutting into question. Clear-cutting is 
economically efficient: all the trees in a 
large tract of forest are cut to the 
ground, stripped of branches, and car- 
ried off to the sawmill. Many years later 
a new forest has usually replaced the old 
one through a revegetation process 
called succession. Ecologists asked 
whether the economically efficient prac- 
tice of removing all the trees, rather 
than selectively cutting choice individ- 
uals, might adversely affect the pattern 
of subsequent forest recovery and per- 
manently damage the land. They were 
particularly concerned about any de- 
cline in soil fertility — the capacity of the 
deep layers of humus to provide the 
mineral nutrients needed for the growth 
and development of later forests. In ma- 
ture stands, much of the nutrient cap- 
ital, such as nitrogen, potassium, and 
calcium, can be tied up in living plant 
tissue or intimately complexed with the 
decomposing layers of organic matter on 
the forest floor. Ecologists wondered 
whether, in addition to the minerals that 
depart with the harvested timber, clear- 
cutting might cause a loss of nutrients 
through erosion and excessive runoff in 
stream water. 
Herbert Bormann of Yale’s School of 
Forestry and Environmental Studies 
and Gene Likens of Cornell University 
decided to test these ideas, and in 1964 
they established the Hubbard Brook Ex- 
perimental Watershed Study on a tract 
of second-growth hardwood forest in the 
White Mountains of central New 
Hampshire. The experimental unit they 
manipulated is known as a watershed, 
an area of forest draining into a single 
stream. Two adjacent watersheds at the 
headwaters of Hubbard Brook were 
chosen: one was to be clear-cut for the 
experiment and the other, the control, 
was to be left uncut. By constructing a 
notched dam, or weir, at the head of 
each stream, they could measure stream 
flow from both watersheds and periodi- 
cally sample the water to assess nutrient 
content and the loss of particulate mat- 
ter from erosion. All the trees in the 
experimental watershed were cut, and 
the effects of devegetation were accen- 
tuated by the application of herbicides 
for three years. After the cut. Bormann 
and Likens, and their students, moni- 
tored the water chemistry and the 
change in the growth and composition of 
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