Nature is underpriced, says economist Partha Dasgupta.
No one pays the mountainside for the trees it grows or the
sea for the fish it provides.
Figuring out the economic values of nature’s services
and incorporating them into such indicators may be one
way to curb destruction of biodiversity. For without a fair
accounting, nature looks like a free lunch, and, Dasgupta
says, “If you don’t pay for something, you overuse it.”
To highlight the economic value of nature on a big scale,
Dasgupta, of the University of Cambridge in England, is push-
ing for a nature-inclusive alternative to the Gross Domestic
Product as an economic indicator.
The GDP reports the total value of
human-made goods and services
without deductions to reflect losses
of capital, especially natural capital.
Gross, as opposed to net, is “the
rogue word” in Gross Domestic
Product, he says.
Dasgupta is now urging nations
and the World Bank to monitor
another measure that he and others have been refining in recent
years. “Comprehensive wealth per capita” adds human and
natural assets to tallies of capital, and should provide a
much-needed way to see whether growth is sustainable, he
argues in the January 12 Philosophical Transactions of the
Royal Society B.
Dasgupta compared GDP to his new measure of wealth
per capita for five countries and for sub-Saharan Africa from
1970 to 2000 (see table). All the nations averaged annual
increases in GDP, and sub-Saharan Africa was slipping only
0.1 percent a year. But when Dasgupta used his wealth
indicator, the figures looked different. He incorporated natu-
ral resources and human resources. With this measure,
sub-Saharan Africa looked even worse than it had based on
GDP, and the nations, except China, slipped from the posi-
tive into the negative column.
Average percent growth in two
economic indicators, 1970–2000
Country/region Wealth per capita GDP per head
Sub-Saharan Africa - 2. 8 -0.1
Bangladesh -0.8 1. 9
India -0.4 3.0
Nepal -0.4 1. 9
Pakistan - 1. 4 2. 2
China 4. 5 7. 8
SoURCE: ADAPTED FRoM DASGUP TA, 2010
What causes that burst of productivity
has led to lively debate. Having more species may increase the chances of getting
one super-producing plant that plumps
up biomass. That scenario, called a sampling effect, could play out in some systems, but Tilman says he thinks his plots
are getting an extra boost from the powers of competition. When species crowd
into an area, they compete for resources
and become efficient at using them.
Experiments so far suggest that sampling effects explain about one-third of
this productivity increase, Cardinale and
his team reported in 2007 in Proceedings
of the National Academy of Sciences. The
other portion, the team says, comes from
ways that species in a mix complement
each other — by promoting growth and
through division of labor.
Plants sprout at the foundation of an
ecosystem’s food web, capturing energy
from the sun. Diversity, though, also has
an effect on the creatures that eat the
plants, says marine ecologist Emmett
Duffy of the College of William & Mary’s
Virginia Institute of Marine Science in
Duffy has worked with flowering plants
called seagrasses that grow entirely under
water. Much of their success depends on
the little arthropods called amphipods
and isopods that graze on the seagrass
blades and remove algal scum that can
dim the light. With more species of grazers at work, over time, algae were cleared
off more efficiently and grazers increased
in number, Duffy says.
Another underwater experiment supports the notion that biodiversity provides stability. A study published in the
December 2009 Ecological Applications