DINOSAURS 
OF NORTH AMERICA 
“brings back to life the 
very different world of 
the distant past — 
with its exotic and 
spectacular creatures.” 
— John H. Ostrom, Curator of 
Vertebrate Paleontology, 
Peabody Museum of Natural 
History, Yale (Jniversity 
^ Now, in the most 
authoritative book of its 
kind — and the first devoted 
exclusively to North America — 
Helen Roney Sattler describes 
more than 80 kinds of dinosaurs 
that roamed the continental 
United States and Canada. For 
140 million years, dinosaurs 
dominated the earth. The fossils 
they left help us to know what 
they really looked like, from 
the gigantic Brachiosaurus, 40 
feet tall and 80 feet long, to 
Nanosaurus, about the size of 
a chicken. 
Dinosaur history is told 
against a background of vast 
geological changes. Included 
is information about exciting 
discoveries being made today 
and the latest theories about 
what caused dinosaurs to 
become extinct. For future 
fossil hunters, this book is a 
must. For everyone, reading it 
will be an adventure. 
DINOSAURS 
OF NORTH AMERICA 
text by Helen Roney Sattler 
illustrated by Anthony Rao 
Ages 8 up $10.95 
FREE DINOSAURS poster 
available. To get your free 13 VY' 
x 15'/z" Stegosaurus poster write to: 
Lothrop,Lee& 
Shepard Books 
A division of William Morrow & Co., Inc. 
Dept. CM-D 
105 Madison Avenue. New York. N.Y. 10016 
the cut forest and compared this with 
the control. 
Bormann and Likens have recently 
published the results of this experiment 
in Pattern and Process in Forested Eco- 
systems (New York: Springer-Verlag, 
1979), and it is a brilliant piece of eco- 
logical investigation. In an effort to 
achieve a broad understanding of forest 
systems, they have constructed an eco- 
system model based on the Hubbard 
Brook data to predict the recovery of a 
forest following the devastation of its 
vegetation. In this model, the ecosys- 
tem — all of the dead and living organ- 
isms as well as the inorganic nutrients — 
is pictured metaphorically as a highly 
integrated organic entity that is sub- 
jected to a serious wound or disturb- 
ance, much like a severe injury suffered 
by an animal. The entire system under- 
goes a process of recovery (succession) 
in which internal homeostatic mecha- 
nisms repair the damage and return the 
system to a normal state. Bormann and 
Likens divide their model of forest re- 
covery into four phases: an early period 
of declining biomass through the de- 
composition of dead slash; a hundred 
years of succession as biomass accumu- 
lates; a transition time when old trees 
begin to die, creating local gaps of dis- 
turbance; and a long-term steady state 
when the forest is a mosaic patchwork of 
mixed-age trees in different stages of 
succession. The goal of this recovery 
process is the original plant community 
that covered the landscape prior to the 
intrusion of humans. This image of a 
primeval forest has haunted plant ecolo- 
gists for more than half a century, 
touching their deepest feelings for un- 
spoiled wilderness. Armed with this con- 
ceptual model and its underlying organ- 
ismic metaphor, Bormann and Likens 
set about interpreting the remarkable 
results of their deforestation experi- 
ment. 
The most fundamental effect of clear- 
cutting was a dramatic increase in the 
volume of stream flow, particularly dur- 
ing spring snowmelt and after heavy 
rainstorms. One midsummer shower in 
1969 generated a peak flow that was 
more than three times higher in the 
cutover watershed than in the control. 
Precipitation, which would normally 
have been absorbed through the roots of 
living plants and transpired via evapora- 
tion into the atmosphere, moved out of 
the watershed in a massive flush of 
water accompanied by enhanced con- 
centrations of nutrients. Dissolved nitro- 
gen, for example, which is so critical to 
the growth of plants, peaked nearly 160 
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