Collapse: How Societies Choose to Fail or Succeed (53 page)

thority may practice top-down management of environmental resources, and may give all of his subjects orders that are good for them in the long
run but that they don't know enough to have formulated themselves.

This top-down approach is as familiar to citizens of modern First World
countries as is the bottom-up approach. We're accustomed to the fact that governmental entities, especially (in the U.S.) state and federal govern
ments, pursue environmental and other policies affecting the whole state or country, supposedly because the government leaders can have an overview
of the state or country beyond the capacity of most individual citizens. For
example, while the citizens of Montana's Bitterroot Valley do have their own
Teller Wildlife Refuge, half of the valley's acreage is owned or managed by
the federal government, as national forest or under the Bureau of Land
Management.

Traditional middle-sized societies, occupying medium-sized islands or
homelands, may not be well suited for either of these two approaches. The island is too large for a local farmer to have an overview of, or stake in, all
parts of the island. Hostility between chiefs in neighboring valleys prevents
agreement or coordinated action, and even contributes to environmental
destruction: each chief leads raids to cut down trees and wreak havoc on ri
vals' land. The island may be too small for a central government to have arisen, capable of controlling the entire island. That appears to have been
the fate of Mangaia, and may have affected other middle-sized societies in
the past. Today, when the whole world is organized into states, fewer middle-
sized societies may be facing this dilemma, but it may still arise in countries
where state control is weak.

To illustrate these contrasting approaches to success, I shall now relate
briefly the story of two small-scale societies where bottom-up approaches
worked (the New Guinea highlands and Tikopia Island), and one large-scale society where top-down measures worked (Japan of the Tokugawa era, now
the eighth most populous country in the world). In all three cases the en
vironmental problems addressed were deforestation, erosion, and soil fer
tility. However, many other past societies have adopted similar approaches
for solving problems of water resources, fishing, and hunting. It should also
be understood that bottom-up and top-down approaches can coexist within
a large-scale society that is organized as a pyramidal hierarchy of units. For
example, in the United States and other democracies we have bottom-up management by local neighborhood and citizens' groups coexisting with top-down management by many levels of government (city, county, state,
and national).

The first example is the highlands of New Guinea, one of the world's great success stories of bottom-up management. People have been living self-sustainably in New Guinea for about 46,000 years, until recent times with
out economically significant inputs from societies outside the highlands,
and without inputs of any sort except trade items prized just for status
(such as cowry shells and bird-of-paradise plumes). New Guinea is the large
island just north of Australia (map, p. 84), lying almost on the equator and
hence with hot tropical rainforest in the lowlands, but whose rugged inte
rior consists of alternating ridges and valleys culminating in glacier-covered
mountains up to 16,500 feet high. The terrain ruggedness confined Euro
pean explorers to the coast and lowland rivers for 400 years, during which it
became assumed that the interior was forest-covered and uninhabited.

It was therefore a shock, when airplanes chartered by biologists and
miners first flew over the interior in the 1930s, for the pilots to see below
them a landscape transformed by millions of people previously unknown to
the outside world. The scene looked like the most densely populated areas
of Holland (Plate 19): broad open valleys with few clumps of trees, divided as far as the eye could see into neatly laid-out gardens separated by ditches
for irrigation and drainage, terraced steep hillsides reminiscent of Java or Japan, and villages surrounded by defensive stockades. When more Euro
peans followed up the pilots' discoveries overland, they found that the in
habitants were farmers who grew taro, bananas, yams, sugarcane, sweet
potatoes, pigs, and chickens. We now know that the first four of those major
crops (plus other minor ones) were domesticated in New Guinea itself, that
the New Guinea highlands were one of only nine independent centers of plant domestication in the world, and that agriculture has been going on there for about 7,000 years
—one of the world's longest-running experi
ments in sustainable food production.

To European explorers and colonizers, New Guinea highlanders seemed
"primitive." They lived in thatched huts, were chronically at war with each
other, had no kings or even chiefs, lacked writing, and wore little or no
clothing even under cold conditions with heavy rain. They lacked metal and
made their tools instead of stone, wood, and bone. For instance, they felled
trees with stone axes, dug gardens and ditches with wooden sticks, and
fought each other with wooden spears and arrows and bamboo knives.

That "primitive" appearance proved deceptive, because their farming
methods are sophisticated, so much so that European agronomists still don't understand today in some cases the reasons why New Guineans'

methods work and why well-intentioned European farming innovations
failed there. For instance, one European agricultural advisor was horrified
to notice that a New Guinean sweet potato garden on a steep slope in a wet area had vertical drainage ditches running straight down the slope. He con
vinced the villagers to correct their awful mistake, and instead to put in drains running horizontally along contours, according to good European
practices. Awed by him, the villagers reoriented their drains, with the result that water built up behind the drains, and in the next heavy rains a landslide
carried the entire garden down the slope into the river below. To avoid exactly that outcome, New Guinea farmers long before the arrival of Euro
peans learned the virtues of vertical drains under highland rain and soil conditions.

That's only one of the techniques that New Guineans worked out by trial
and error, over the course of thousands of years, for growing crops in areas
receiving up to 400 inches of rain per year, with frequent earthquakes, land
slides, and (at higher elevations) frost. To maintain soil fertility, especially in
areas of high population density where short fallow periods or even continuous growing of crops were essential to produce enough food, they re
sorted to a whole suite of techniques besides the silviculture that I'll explain
in a moment. They added weeds, grass, old vines, and other organic matter
to the soil as compost at up to 16 tons per acre. They applied garbage, ash
from fires, vegetation cut from fields resting in fallow, rotten logs, and chicken manure as mulches and fertilizers to the soil surface. They dug
ditches around fields to lower the watertable and prevent waterlogging, and transferred the organic muck dug out of those ditches onto the soil surface.
Legume food crops that fix atmospheric nitrogen, such as beans, were rotated with other crops
—in effect, an independent New Guinean invention
of a crop rotation principle now widespread in First World agriculture for
maintaining soil nitrogen levels. On steep slopes New Guineans constructed terraces, erected soil retention barriers, and of course removed excess water
by the vertical drains that aroused the agronomist's ire. A consequence of
their relying on all these specialized methods is that it takes years of growing up in a village to learn how to farm successfully in the New Guinea highlands. My highland friends who spent their childhood years away from
their village to pursue an education found, on returning to the village, that they were incompetent at farming their family gardens because they had
missed out on mastering a large body of complex knowledge.

Sustainable agriculture in the New Guinea highlands poses difficult
problems not only of soil fertility but also of wood supplies, as a result of

forests having to be cleared for gardens and villages. The traditional highland lifestyle relied on trees for many purposes, such as for timber to build
houses and fences, wood for making tools and utensils and weapons, and
fuel for cooking and for heating the hut during the cold nights. Originally,
the highlands were covered with oak and beech forests, but thousands of
years of gardening have left the most densely populated areas (especially the
Wahgi Valley of Papua New Guinea and the Baliem Valley of Indonesian
New Guinea) completely deforested up to an elevation of 8,000 feet. Where
do highlanders obtain all the wood that they need?

Already on the first day of my visit to the highlands in 1964,1 saw groves
of a species of casuarina tree in villages and gardens. Also known as she-
oaks or ironwood, casuarinas are a group of several dozen tree species with
leaves resembling pine needles, native to Pacific islands, Australia, Southeast Asia, and tropical East Africa, but now widely introduced elsewhere because
of their easily split but very hard wood (hence that name "ironwood"). A
species native to the New Guinea highlands,
Casuarina oligodon,
is the one
that several million highlanders grow on a massive scale by transplanting
seedlings that have sprouted naturally along stream banks. Highlanders
similarly plant several other tree species, but casuarina is the most prevalent. So extensive is the scale of transplanting casuarinas in the highlands
that the practice is now referred to as "silviculture," the growing of trees in
stead of field crops as in conventional agriculture
(silva, ager,
and
cultura
are the Latin words for woodland, field, and cultivation, respectively).

Only gradually have European foresters come to appreciate the particular advantages of
Casuarina oligodon,
and the benefits that highlanders obtain from its groves. The species is fast-growing. Its wood is excellent for
timber and fuel. Its root nodules that fix nitrogen, and its copious leaf-fall,
add both nitrogen and carbon to the soil. Hence casuarinas grown inter
spersed in active gardens increase the soil's fertility, while casuarinas grown
in abandoned gardens shorten the length of time that the site must be left
fallow to recover its fertility before a new crop can be planted. The roots hold soil on steep slopes and thereby reduce erosion. New Guinea farmers claim that the trees somehow reduce garden infestation with a taro beetle,
and experience suggests that they are right about that claim as they are
about many others, though agronomists still haven't figured out the basis of the tree's claimed anti-beetle potency. Highlanders also say that they appre
ciate their casuarina groves for esthetic reasons, because they like the sound
of the wind blowing through the branches, and because the trees provide
shade to the village. Thus, even in broad valleys from which the original for-

est has been completely cleared, casuarina silviculture permits a wood-dependent society to continue to thrive.

How long have New Guinea highlanders been practicing silviculture? The clues used by paleobotanists to reconstruct the vegetational history of the highlands have been basically similar to those I already discussed for
Easter Island, the Maya area, Iceland, and Greenland in Chapters 2-8: analy
sis of swamp and lake cores for pollen identified down to the level of the
plant species producing the pollen; presence of charcoal or carbonized par
ticles resulting from fires (either natural or else lit by humans to clear
forests); sediment accumulation suggesting erosion following forest clear
ance; and radiocarbon dating.

It turns out that New Guinea and Australia were first settled around
46,000 years ago by humans moving eastwards from Asia through Indone
sia's islands on rafts or canoes. At that time, New Guinea was still joined in a
single landmass to Australia, where early human arrival is well attested at
numerous sites. By 32,000 years ago, the appearance of charcoal from frequent fires and an increase in pollen of non-forest tree species compared to
forest tree species at New Guinea highland sites hint that people were al
ready visiting the sites, presumably to hunt and to gather forest pandanus nuts as they still do today. Signs of sustained forest clearance and the ap
pearance of artificial drains within valley swamps by around 7,000 years ago
suggest the origins of highland agriculture then. Forest pollen continues to
decrease at the expense of non-forest pollen until around 1,200 years ago,
when the first big surge in quantities of casuarina pollen appears almost si
multaneously in two valleys 500 miles apart, the Baliem Valley in the west and the Wahgi Valley in the east. Today those are the broadest, most exten
sively deforested highland valleys, supporting the largest and densest human populations, and those same features were probably true of those two
valleys 1,200 years ago.

If we take that casuarina pollen surge as a sign of the beginning of ca
suarina silviculture, why should it have arisen then, apparently indepen
dently in two separate areas of the highlands? Two or three factors were
working together at that time to produce a wood crisis. One was the ad
vance of deforestation, as the highland's farming population increased from
7,000 years ago onwards. A second factor is associated with a thick layer of
volcanic ashfall, termed the Ogowila tephra, which at just that time blan
keted eastern New Guinea (including the Wahgi Valley) but wasn't blown as far west as the Baliem Valley. That Ogowila tephra originated from an enor
mous eruption on Long Island off the coast of eastern New Guinea. When I