BIOPLAN POSTING 2001-5-10
BIOPLAN POSTING 2001-5-10
David.Duthie@unep.org
Sent by: owner-bioplan@undp.org
05/09/01 09:00 AM
bioplan
David.Duthie@unep.org
Dear BIOPLANNERS,
Agriculture has been highlighted as a major threat to global biodiversity
in two important publications which describe the need for a radical
overhaul in current trends in agricultural practice.
Agriculture is clearly major driving force behind land clearance and
land
degradation, yet more appropriate land use for agriculture also holds
the
key to reconciling the needs of humans and the rest of the world's
biodiversity.
The first posting is (I believe) written by David Tilman and was published
in Science, but I do not have the full reference to hand. This
lays out
the magnitude of the problem at a global scale.
The second is promoting a new report from IUCN and Future Harvest written
by Jeff McNeely and Sara Scheer called: "Common Ground, Common Future:
How
Ecoagriculture Can Help Feed the World and Save Wild Biodiversity"
and can
be downloaded as a pdf file (2.4MB) from:
http://www.futureharvest.org/pdf/biodiversity_report.pdf
This report outlines the potential for agriculture and wild biodiversity
to
become more compatible.
These postings are a little long, but well worth reading, and reacting to!
Best wishes
David Duthie
****************************************************************************************
Forecasting Agriculturally Driven Global Environmental Change
Abstract
During the next 50 years, which is likely to be the final period of
rapid
agricultural expansion, demand for food by a wealthier and 50% larger
global population will be a major driver of global environmental change.
Should past dependences of the global environmental impacts of agriculture
on human population and consumption continue, 109 hectares of natural
ecosystems would be converted to agriculture by 2050. This would be
accompanied by 2.4- to 2.7-fold increases in nitrogen- and
phosphorus-driven eutrophication of terrestrial, freshwater, and near-shore
marine ecosystems, and comparable increases in pesticide use. This
eutrophication and habitat destruction would cause unprecedented ecosystem
simplification, loss of ecosystem services, and species extinctions.
Significant scientific advances and regulatory, technological, and
policy
changes are needed to control the environmental impacts of agricultural
expansion.
During the first 35 years of the Green Revolution, global grain production
doubled, greatly reducing food shortages, but at high environ-mental
cost.
In addition to its effects on greenhouse gases, agriculture affects
ecosystems by the use and release of limiting resources that influence
ecosystem functioning (nitrogen, phosphorus, and water), release of
pesticides, and conversion of natural ecosystems to agriculture. These
sources of global change may rival climate change in environ-mental
and
societal impacts. Population size and per capita consumption are assumed
to
be the two greatest drivers of global environ-mental change. Humans
currently appropriate more than a third of the production of terrestrial
ecosystems and about half of usable freshwaters, have doubled terrestrial
nitrogen supply and phosphorus liberation, have manufactured and released
globally significant quantities of pesticides, and have initiated a
major
extinction event. Global population, which increased 3.7-fold during
the
20th century, to 6 billion people, is forecast to increase to 7.5 billion
by the year 2020 and to about 9 billion by 2050. Constant-dollar global
per
capita gross domestic product (GDP) increased 4.6-fold in the 20th
century
and is projected to be 1.3 times current levels by 2020 and 2.4 times
current levels by 2050. How might projected increases in population
and
wealth influence the global environment? The prospects of climate change
are widely recognized. Here, we explore the nonclimatic global
environmental impacts of agricultural expansion during the coming 20
to 50
years. We use past global trends and their dependence on global population
and GDP to empirically forecast the potential global environmental
impacts
of agriculture. Like economic forecasting, ecological forecasting is
notoriously difficult and imprecise. Our forecasts are not predictions,
but
rather are estimates of environmental impacts should agriculture continue
on the trajectories of the past 35 or more years. Because these
trajectories include in them the impacts of past technological
developments, changes in consumer choices, and environmental regulations,
our forecasts implicitly assume similar technological, regulatory,
and
behavioral changes in the future. Shifts in these could cause major
deviations from our forecasts.
We use univariate and multiple regressions to forecast future global
trends
for each of seven environmental variables related to agriculture (Table
1).
Because of the exponential nature of past global population and economic
growth, we had anticipated exponential temporal trends for these variables.
Surprisingly, each was a linear, and almost equally strong, function
of
time, population, and GDP. We thus use linear fits in our forecasts,
while
recognizing that substantial changes in future population and economic
growth, agricultural policies, climate, and other factors would affect
our
results. Detailed regional forecasts and forecasts based on mechanistic
models that couple regional economies, agriculture, and the environment
are
also needed and would complement our simpler global approach.
Four forecasts were made for each variable: by a linear fit to its temporal
trend, extrapolated to the years 2020 and 2050; by the fitted dependence
of
each variable on population size, combined with the global population
size
projected for 2020 and 2050; by the linear dependence of each variable
on
GDP, combined with global GDP projections for 2020 and 2050; and by
multiple regression fitting each variable to year, population, and
per
capita GDP, combined with projected values for these in 2020 and 2050.
We
present all four forecasts for 2050 to illustrate similarity and
variability, and mean forecasts for 2020 and 2050. The averages for
2020
allow a mid-course evaluation of the 50-year forecasts.
Table 1. Univariate and multivariate forecasts for years 2020 and 2050,
based on trends observed in the past 35 to 40 years and their dependence
on
population and GDP. Parentheses show R 2 values for each regression.
Levels
of significance: **P , 0.0001; *P , 0.01; NS, P . 0.05. The value in
2000
is based on temporal extrapolation from the latest available data,
generally 1998. Mean projections are means of the three univariate
and the
one multivariate projection.
----------------------------------------------------------------------------------------------------------
|----------+------------+------------+--------------+--------+------------|
| |Fertilzer
|Irrigated | Pesticide |
|Pasture land|
| |(106 MT)
|Land |
|Crop |(109 ha) |
| |
| (106 ha) |
|land |
|
| |
| |
|(109 ha)|
|
|----------+------------+------------+--------------+--------+------------|
| |
| |
|Produced|Imported |
| |
| |
|(106 MT)|(109 1996 US|
| |
| |
| |$)
|
|----------+------------+------------+--------------+--------+------------|
| |N
|P |
| |
|
|----------+------------+------------+--------------+--------+------------|
|Value in |87
|34.3 |280
| 3.75 |11.81.543.47|
|2000 |
| |
| |
|
|----------+------------+------------+--------------+--------+------------|
| |
| |Mean
| |
|
| |
| |projections
| |
|
|----------+------------+------------+--------------+--------+------------|
|Forecast |135
|47.6 |367
| 6.55 |18.51.663.67|
|2020 |
| |
| |
|
|----------+------------+------------+--------------+--------+------------|
|Forecast |263
|83.7 |529
| 10.1 |32.21.894.01|
|2050 |
| |
| |
|
|----------+------------+------------+--------------+--------+------------|
----------------------------------------------------------------------------------------------------------
The doubling of global food production during the past 35 years was
accompanied by large increases in global nitrogen (N) and phosphorus
(P)
fertilization and irrigation. If past trends in N and P fertilization
and
irrigation and their dependence on population and GDP continue, our
mean
fore-cast is for global N fertilization to be 1.6-fold times present
amounts by 2020 and 2.7 times present values by 2050. By 2050, N
fertilization alone would annually add 236 3 106 MT of N to terrestrial
ecosystems, compared with 140 3 106 MT from all natural sources. Individual
forecasts for N fertilization in 2050 range from a 1.9-fold increase
based
on its dependence on population to a 3.9-fold increase based on GDP.
P
fertilization is forecast to be 1.4 times current amounts in 2020 and
2.4
times current amounts in 2050. P estimates for 2050 range from 1.6-fold
to
3.4- fold increases. Irrigated area, a measure of agricultural demand
for
water, is forecast to be 1.3 times the current area in 2020 and 1.9
times
as great in 2050.
Humans annually already release as much N and P to terrestrial ecosystems
as all natural sources. The large projected increases in N, P, and
irrigation water would have significant environmental impacts. Irrigation
increases salt and nutrient loading to downstream aquatic ecosystems,
can
cause salinization of soils, and has impacts on streams and rivers
because
of damming and removal of water. In many areas, there is insufficient
water
for projected demands. N and P leakage from agricultural systems causes
major environmental problems. About half of fertilizer N and P is captured
in harvested crops and, after consumption, enters human and livestock
waste
streams. About 70% of harvested crops are fed to livestock in developed
countries, but few livestock wastes are treated for N and P removal.
Thus,
much N and P from fertilizer and animal wastes enters surface and
groundwater, and N also is volatilized to the atmosphere as ammonia
and
deposited regionally.
The major environmental consequence of P addition is eutrophication
of
surface waters, particularly freshwater lakes and streams. For N,
consequences include eutrophication of estuaries and coastal seas,
loss of
biodiversity and changes in species compositions in terrestrial and
aquatic
ecosystems, groundwater pollution with nitrate and nitrite, increases
in
the green-house gas N2O, increases in NOx and resulting tropospheric
smog
and ozone, and acidification of soils and sensitive freshwaters.
Eutrophication is the biggest pollution problem in most coastal waters,
and, with overfishing and aquaculture, is a major threat to marine
biodiversity. Agricultural nutrient pollution has led to increased
blooms
of toxic algae in many coastal systems and to the large hypoxic ("dead")
zone in the Gulf of Mexico. In total, projected increases in N and
P
fertilization and irrigation would cause significant losses of
biodiversity, as well as marked changes in the composition and functioning
of both terrestrial and aquatic ecosystem.
Although society benefits from pesticides, some cause environmental
degradation or affect human health. Some pesticides, de-pending on
persistence and volatility, disperse globally, bio accumulate in food
chains and have impacts on human health and the health of other species
far
from points of release and many years after release. If past patterns
continue, global pesticide production, which has increased for 40 years,
would be 1.7 times that at present by 2020 and 2.7 times the present
amount
by 2050. Projections for 2050 range from 1.9- to 4.8-fold increases.
World
trade in pesticides, another estimate of trends in pesticide use, would
be
1.6 times present levels by 2020 and 2.7 times present levels by 2050.
Should trends continue, by 2050, humans and other organisms in natural
and
managed ecosystems would be exposed to markedly elevated levels of
pesticides.
Land use and habitat conversion are, in essence, a zero-sum game: land
converted to agriculture to meet global food demand comes from forests,
grasslands, and other natural habitats. Increases in agricultural land,
a
major quantified cause of global habitat destruction, are a conservative
estimate of losses of native ecosystems. Global trends for pastureland
suggest a net increase of 2.0 3 108 hectares of pasture by 2020 and
of 5.43
108 hectares by 2050. If past trends continue, global cropland would
in-crease by a net of 1.23 108 hectares by 2020 and of 3.53 108 hectares
by
2050. The combined total represents an average global agricultural
land
base in 2050 that would be 18% larger than at present. These are net
global
changes. Because analyses like those of Table 1, but for developed
countries, project a net withdrawal of 1.43 108 ha of land from agriculture
by 2050, the net loss of natural ecosystems to cropland and pasture
in
developing countries by 2050 would be 109 ha, about half of all potentially
suitable remaining land.
The conversion of 109 hectares of land to agriculture would represent
the
worldwide loss of natural ecosystems larger than the United States.
Because
of regional availabilities of suit-able land, this expansion of
agricultural land is expected to occur predominately in Latin America
and
sub-Saharan central Africa. It could lead to the loss of about a third
of
remaining tropical and temperate forests, savannas, and grasslands
and of
the services, including carbon storage, provided by these ecosystems.
Additional natural habitat would be lost worldwide to urban and suburban
development, to roadways, and to the rotation of low-quality lands
through
agriculture. Species extinction is an irreversible impact of habitat
destruction. Interactions between climate change, species invasions,
and
habitat fragmentation could cause further diversity losses, because
many
species may be unable to migrate through fragmented habitats to reach
regions with suitable climates and soils.
Just as demand for energy is the major cause of increasing atmospheric
greenhouse gases, demand for agricultural products may be the major
driver
of future nonclimatic global change. Our forecasts have high variance,
but
even the lowest projections are cause for concern. The projected 50%
increase in global population and demand for diets richer in meat by
a
wealthier world are projected to double global food demand by 2050,
creating an environmental challenge that may rival, and significantly
inter-act with, climatic change. The actual impacts of agricultural
expansion will depend on how large the expansion actually is and on
how it
is achieved. Our projections of global environ-mental impacts assume
a
continuation of past practices, i.e., mainly of agricultural
intensification by means of fertilization, irrigation, pesticide
application, and crop breeding. We implicitly assume that the increasing
yields of the Green Revolution can continue unabated for 50 more years.
If
this does not occur, perhaps be-cause of water shortages, evolution
of
resistant pests and pathogens, emergence of new pests and pathogens,
or
diminishing returns from fertilization and selection for higher-yielding
varietie, the projected food demand would be met only if the agricultural
land base increased more than we have projected, i.e., by an
extensification of agriculture. Alternatively, food demand could be
lowered
if the trend toward diets richer in meat were reversed or if global
population stabilized at a lower than projected level.
The Green Revolution greatly reduced world hunger. Comparable advances
in
agricultural production are needed during the coming 50 years to assure
a
sufficient, secure, and equitable global food supply, but these advances
must follow new trajectories if the problems we have identified are
to be
minimized. An environmentally sustainable revolution, a greener revolution,
is needed. It must be based on the total costs and benefits of agriculture,
including agriculture-dependent gains and losses in values of such
ecosystem goods and services as potable water, biodiversity, carbon
storage, pest control, pollination, fisheries, and recreation.
Existing knowledge, if widely used, could significantly reduce the
environmental impacts
Integrated pest management, application of site-and time-appropriate
amounts of agricultural chemicals and water, use of cover crops on
fallow
lands and buffer strips between cultivated fields and drainage areas,
and
appropriate deployment of more productive crops can in-crease yields
while
reducing water, fertilizer, and pesticide use and movement to
nonagricultural habitats. Treatment of animal wastes is necessary,
especially in developed countries, where more than a third of fertilizer
N
passes through livestock. Currently, animal wastes receive little or
no
treatment and are a major source of surface water pollution and terrestrial
N deposition. Preservation and restoration of wetlands and riparian
zones
can remove N by denitrification before it reaches watercourses and
can trap
P in soils.
Comprehensive land-use planning could mitigate some effects of agricultural
expansion. Some agricultural impacts could be ameliorated if the 1.4
3 108
hectares projected for removal from agriculture in developed nations
were
re-stored to provide ecosystem services, such as carbon storage,
preservation of biodiversity, and production of potable water.
Alternatively, if kept in agriculture, this land could save a comparable
area of natural ecosystems in developing nations from destruction if
food
so produced could meet demands of developing nations. The capability
of the
remaining natural lands to supply ecosystem services and to pre-serve
biodiversity could be increased by planning the pattern and location
of
agricultural development so as to save biodiversity hot spots; to minimize
fragmentation; to maximize the range of ecosystem types preserved;
and to
preserve wetlands and riparian zones that protect surface waters from
inputs of nutrients, pesticides, eroded soil and pathogens. Such actions
would continue a global trend of setting land aside as nature reserves
and
national parks. Cumulatively worldwide, an area roughly the size of
the
Indian subcontinent is designated for conservation of biodiversity.
Many
pre-serves, though, are inadequately protected, and some may be sustainably
protected only if incorporated into local economies.
Even the best available technologies, fully deployed, cannot prevent
many
of the forecasted problems. Major international programs are needed
to
develop new technologies and policies for ecologically sustainable
agriculture. Region appropriate education, incentives, and le-gal
restrictions will be required to encourage adoption. The research needs
are
diverse. We must seek, by breeding and biotechnology, gains in the
fundamental efficiency of crop N, P, and water use. Advances in precision
agriculture that decrease N and P inputs are needed, as are methods
that
manage soil organic matter and microbial communities to reduce nutrient
leaching and to optimize soil fertility. Methods are needed to efficiently
close the nutrient cycle from soil to crop to livestock and back to
agricultural soil, and to prevent the occurrence and the spread to
humans
of livestock pathogens. Ways to better control crop pathogens and pests
are
needed, such as by greater use of natural enemies, crop diversity,
and
biotechnology, if deployed so as to reduce evolution of pest resistance.
Methods to forecast quantitatively the impact on ecosystem functioning
of
loss of habitat, loss of biodiversity, changes in species composition,
and
in-creased nutrient inputs need development. Be-cause most agricultural
expansion will occur in developing countries, the discovery and adoption
of
appropriate practices likely would re-quire aid from developed countries,
including International Monetary Fund and World Bank loans, or debt
forgiveness. Moreover, regional differences in food demand and in the
potential of extensification versus intensification to meet these needs
means that, although the problems are global, solutions must be local,
regional, and global.
If global population stabilizes at 8.5 to 10 billion people, the next
50
years may be the final episode of rapid global agricultural expansion.
During this period, agriculture has the potential to have massive,
irreversible environmental impacts. The minimization of these impacts,
while providing sufficient and equitably distributed food, will be
a great
challenge. Although there are likely to be mechanisms and policies
that can
reduce, or perhaps reverse, many of the trends that we have identified,
these solutions will not be achieved unless far more re-sources are
dedicated to their discovery and implementation.
*******************************************************
Half the World's Nature Reserves Heavily Farmed
By Cat Lazaroff
LONDON, England, May 8, 2001 (ENS) - Two of the world's leading
environmental and agriculture groups reported today that almost half
of
the world's 17,000 major nature reserves, which are intended to
protect
wildlife from extinction, are being heavily used for agriculture.
They
also report that extreme malnutrition and hunger are pervasive
among
people living in at least 16 of the world's 25 key biodiversity
hotspots,
where wildlife is most at risk.
The findings, documented in an unprecedented joint report
by The World
Conservation Union (IUCN) and the Washington, DC based agriculture
organization Future Harvest, are called "alarming" by the researchers.
Given that clearing and using land for agriculture is the
chief cause of
biodiversity extinction and that widespread hunger is persistent
in areas
with the world's richest biodiversity, many plants and animals
will go
extinct unless ecosystems are managed to feed people and protect
wild
species simultaneously, the report warns.
Biodiversity refers to the entire array of wild plants, animals,
insects
and microorganisms found in nature, which are important to global
ecology
and are also valuable to science and industry.
The report outlines a new solution to the biodiversity extinction
crisis
based on a new understanding of wildlife biology and ecology, on the
ground experimentation, and major scientific advances in genetics,
remote
sensing and other fields.
The approach, called ecoagriculture, seeks to help farmers, most
urgently
those living in or near biodiversity hotspots, to grow more food
while
conserving habitats critical to wildlife. The approach dramatically
breaks
with both traditional conservation policies and common agriculture
techniques.
The report, "Common Ground, Common Future: How Ecoagriculture
Can Help
Feed the World and Save Wild Biodiversity,"
provides for the first time
a comprehensive summary of the interactions between wild biodiversity
and
agriculture around the world. It was commissioned by Future Harvest
and
developed over a two year period through a systematic review of existing
agricultural and ecological literature and local farming practices.
"Many people believe that biodiversity can
be preserved simply by
fencing it off," said co-author Jeffrey McNeely, chief scientist
of
IUCN-The World Conservation Union. "Our report shows that agriculture
and
biodiversity are inextricably linked. In fact, farms and nature
reserves
are actually sharing common ground in many countries where species
are
most at risk."
"To avert widespread extinctions and feed the world, we must
integrate
biodiversity preservation into all landscapes - from grazing
lands to
coffee plantations to rice paddies," McNeely added. "Our research
shows
that ecoagriculture is being successfully used on six continents
around
the globe."
Wild biodiversity in all of its forms has intrinsic value, but
it also has
practical value, such as maintaining the essential balance of the
Earth's
atmosphere, protecting watersheds, renewing soil and recycling
nutrients -
roles essential for farming.
"The ecoagriculture approach recognizes the fact that endangered
species
and desperately poor humans occupy the same ground," said co-author
Sara
Scherr, fellow of the nonprofit Forest Trends and adjunct professor
in the
Agricultural and Resources Economics Department at the University
of
Maryland. "Ecoagriculture could transform agriculture and environmental
protection to save wild biodiversity while also addressing the
realities
of human hunger and population growth."
Protected areas intended to preserve biodiversity
encompass 10 percent
of the Earth's land surface. But today's report states
emphatically that
the world's protected areas are not sufficient to maintain the
world's
wild biodiversity.
According to the report, 45 percent of the world's major protected
reserves are themselves heavily used for agriculture. In other
reserves,
protected areas are interspersed with agricultural land, overlap
with
agricultural land, or are located adjacent to major agricultural
frontiers.
If only the existing protected areas were to continue as wildlife
habitat, between 30 and 50 percent of the species in those areas
would be
lost, because the protected areas do not contain large enough
populations
to maintain the species.
"Protected areas are fast becoming islands of dying biodiversity
because
of the agricultural areas that surround them," explained McNeely.
"Many
animals need the ability to migrate in order to avoid extinction.
Limited
reserve areas cannot fill this need and the lands that would
be needed for
the massive expansion of protected areas is already being used
to feed
local people and fuel local economies."
"Ecoagriculture offers a solution to this dilemma by allowing
farmers to
produce more food on the same amount of land while greatly reducing
harm
to wildlife," McNeely said.
More than 1.1 billion people - 20 percent of the world's population
- live
within the 25 most threatened, species rich areas of the world,
named
biodiversity hotspots by Conservation International. The report
says the
majority of these hotspots are also located in areas with very
high
malnutrition - home to fully one quarter of all the undernourished
people
in the developing world.
In 19 of the world's 25 biodiversity hotspots, population is growing
more
rapidly than in the world as a whole. The report finds that population
in
the sparsely populated tropical wilderness areas is growing,
on average,
at an annual rate of 3.1 percent - more than double the worldwide
average.
If forest clearing continues at present rates, the world's forests
could
lose more than half of their remaining species in the next 50 years,
the
researchers warn. Today, almost 24 percent of mammals, over 12
percent of
birds, and almost 14 percent of plants are threatened with extinction.
The report documents six key ecoagriculture strategies in use
around the
world. These methods can help farmers in industrialized and developing
countries protect wild species and conserve habitat on and near
their land
while increasing agricultural production and farmer incomes,
the report
argues.
The strategies include:
(i) establishing networks of wildlife habitat in non-farmed
areas and
connecting these with larger protected areas;
(ii) integrating perennial plants into farming systems to mimic
natural
habitats such as forests and savannas;
(iii) deploying farming methods that reduce pollution;
(iv) increasing agricultural productivity on lands already being farmed
to
reduce further conversion of land to agriculture;
(v) modifying
resource management in crop fields and other productive areas to enhance
their value as wildlife habitat; and
(vi) establishing protected
areas near farming plots, ranch land and fisheries.
The report provides several dozen case studies of successful
ecoagriculture systems being undertaken in Australia, the United
Kingdom,
the United States, Canada, Europe, Latin America, Africa, and
Asia.
"Farmers and scientists around the world are pioneering a whole
new
approach to agriculture," said McNeely. "These innovations show that
ecoagriculture can be productive and profitable while protecting
biodiversity. They are based on the belief - borne out by empirical
evidence - that humans and wild species can share common ground
and
prosper in a common future."
Scherr said that in the past it was not known which species of
insects,
plants and animals would be harmful to farm production, and all
were
cleared away. But many such farm practices destroy useful wildlife
habitat
without contributing to farm productivity.
"Many of the new approaches in ecoagriculture will require
a change in
mindset for many farmers," said Scherr. "For centuries,
farmers have
generally done their best to clear land of natural vegetation
and keep
wildlife off their farms. This was the sign of a good farmer.
Now we're
asking farmers to let some of the wild back in."
With a new understanding of wildlife biology, these relationships
between
wildlife and agriculture are now better understood, Scherr said.
"We are not suggesting that elephants should be allowed to trample
farmers' fields," said Scherr. "We are saying that there are strategic
solutions for conserving wild biodiversity and producing food on the
same
land."
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