As forests are set aside as reserves, usually in the regions of the highest diversity, the question of reserve
size comes into play. Obviously as much land as possible should be protected to some degree, but whether to keep
a single large reservoir or several small reserves has been a controversial issue in conservation biology over
the past two decades. Bitter fighting between the two camps in the SLOSS debate (single large or several small)
has resulted in squandered time, money, resources, and credibility, and has divided groups that should be united in
saving the planet's environment. A single large reserve is advantageous because it possesses larger populations
of each species and a more stable environment. On the other hand, a single large reserve is subject to devastation
by a single catastrophic event like a fire, flood, or disease. Breaking the reserve into separate pieces reduces
the risk of complete population loss by a single event, but diminishes the size of the species populations and
puts them at a higher risk of extinction. In addition, if the reserve is too small it may experience system decay
resulting in the loss of many species. Small reserves are particularly affected by the invasion of alien species. Studies
have shown that domestic mammals will venture up to three miles (5 km) into the rainforest, not only introducing disease
and alien plant seeds, but also eating eggs, destroying nests, and crushing seedlings. Finally many species require a certain
threshold-population size or range to persist.
Large reserves protect a larger area, including varied habitats, like
eco-tones, forest edges, interior clearings, swamps, and ridges, which mean more niches, and hence greater diversity.
It is important to preserve such zones, which both provide for and produce biodiversity.
Are Forest Fragments Worth Saving?
Several studies have demonstrated the effects from a reduction in reserve
size, including two famous projects in Latin America: Barro Colorado Island, Panama, and Lovejoy's experiment in
the Brazilian Amazon (discussed in chapter 3).
Barro Colorado Island was once a forested hilltop amid a rich tropical rainforest. When the Panama Canal was constructed,
the Chagres river was dammed and the valley was flooded, leaving the hilltop an island of six square miles of forest.
Barro Colorado Island was declared a biological reserve in 1923 and since has been the center of intensive research
(since 1946 the island has been a research site run by the Smithsonian Institution). Over the last seven decades,
researchers have recorded profound changes in the animal population. Large predators like the jaguar, puma, and
harpy eagle were the first to go. Without large predators, mammals like pacas, agoutis, peccaries, and coatimundis populations skyrocketed to levels 2-10 times their normal concentration. However, by 1970, 45 birds species
had disappeared due to the increased omnivore population, the loss of niches like meadows and forest edges, and the
loss of area. Today toll has climbed to 65 bird species lost since the island's formation. Similar results have been recorded
on islands created by hydroelectric projects in Thailand (Chiew Larn Hydroelectric Reservoir) and Venezuela (reservoir
created by the Guri dam).
To avoid further conflicts and help mitigate the problems with reserve size, some biologists have suggested a compromise
solution, which is to create a series of small reserves connected by corridors of forest. This set-up would allow
migration between the sections, but help protect against a mass die-off caused by a single event. Corridors are
especially important should global warming occur, since species must be able to migrate as the climate changes.
But more research is required to find the optimal reserve size and layout for sustaining the most biodiversity.
Until just recently, governments and industry have failed to recognize that tropical rainforests are worth much
more than the attractive hardwood timber they contain. They failed to take account of the intricate role rainforests
play in hydrological, biological, geochemical, and climatological functioning on Earth. Because all the benefits
provided by forests cannot be directly measured and captured, the market under-provides for, hence undervalues,
rainforests. True economic analysis should take these indirect values and this economic distortion into account.
New ways to measure the value of ecosystems
Millennium Ecosystem Assessment (United Nations)
In March 2004, the Millennium Ecosystem Assessment (MEA) was published by the United Nations, consisting of the first global survey of ecological services. The assessment involves more than 1,400 experts in various scientific fields from 95 countries around the world. What makes the report different from other global audits is the MEA’s focus not on surveying biological diversity within any given region, but rather on the general stability of the services provided by world ecosystems. Up until recently, the exchange of natural habitat for cultivated land had been largely beneficial to humans. But things are beginning to change and about two-thirds of the ecosystems reviewed by the MEA are being degraded or used unsustainably.
Total Wealth (World Bank)
In 2005 the World Bank developed a new metric for measuring the wealth of a country—one that accounts for the actual value of natural resources, including resource depletion and population growth. Topping the list are eight European countries, the United States, and Japan, while the bottom of the list is dominated by sub-Saharan African nations.
Other articles of note:
Carbon in Canada's boreal forest worth $3.7 trillion. Ecosystem services estimated at $93 billion per year November 25, 2005
Rainforests worth $1.1 trillion for carbon alone in "Coalition" nations November 29, 2005
The Problem with GDP as a Measure of
Companies that destroy the rainforest should be required to make bioeconomic
and cost-benefit analysis a mandatory part of their land-survey routine. Genuine bioeconomic analysis will survey
all relevant opportunity costs and determine the presence of species with value as pharmaceutical, food, and other
products useful to humankind. In addition, bioeconomic analysis can predict the potential for eco-tourism and ideally,
make some assessment for the services (like climate stabilization, recreation value, soil protection, and clean
water) a forest area provides. By accounting for these benefits it will help guard against the uninformed destruction
of species. Globally, ecosystems and the services they provide are estimated to be worth $33 trillion. The biodiversity
of tropical rainforests can provide material benefits beyond simple value as forest products. For example, in the
late 1970s, Malaysia imported weevils from Cameroon to pollinate oil-palm plantations, in 1981 saving $120 million in labor
costs from hand pollination. Finding this cost-saving species was straightforward: weevils are the natural
pollinators of oil palm, which originated in the rainforests of Cameroon. Once a bioeconomic analysis is complete,
the decision can be made on how to best use the forests; whether to protect them using their sustainable yield or to destroy
them for immediate return and accept the long-term effects.
Some environmentalists say that putting a dollar value on the resource is not the proper way to approach conservation,
since (they will argue) ecosystems have intrinsic and aesthetic values that transcend economic value. They
worry that saying a square kilometer of Malaysian mangrove forest has a value of $300,000 in flood control alone
will justify developers offering $310,000 for the land and turning it into a shopping complex. However, it is clear
that money is a prime consideration in today's global economy, and putting monetary value on an ecosystem, even
if it is undervalued, provides strong evidence to local communities about the value of protecting biodiversity
and the ecosystem.
Even cost-benefit analysis often underestimates the value of the species
and ecosystem by failing to factor in the unknown benefits. Bioeconomic analysis may be able to valuate rainforest
lands by eco-tourism potential, known, and even some unknown products, but it can hardly account for the services
that the rainforest ecosystem performs or the value of unknown biodiversity. How much is a stable climate worth?
What would a country pay for clean water or navigable waterways? At what cost should global warming and polar ice
melt be avoided? How about functioning hydroelectric projects, working fisheries, and avoiding cycles of flood
and drought? These are some items on a long list of services which rainforests provide humanity.
Dismantling rainforests for timber and pasture land is not maximizing their potential yield: it is like smashing
an ancient Roman vase to reach the nickel that fell inside. Razing rainforests for just these simple commodities
is a colossal waste of their resources.
- How does reserve size or area impact levels of biodiversity?
- Why is economic anaylsis of ecosystems important?
[full photo version]
Continued: Funding and Organizaion for Rainforest Conservation
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