Infinite value of mangroves

Sahotra Sarkar writes:

[I]ntact mangroves along coasts (parts of Bengal, parts of the Andamans and Nicobars) provide incomparable protection against tidal waves and other disasters--here's a report from the BBC. (And this benefit is in addition to the economic benefits [fish] brought by intact mangroves to local communities.)

From the Asian tsunami to Katrina, the message should be obvious: where they still exist, we must protect our coastal ecosystems; where they do not (as in much of our Gulf coast) we must reconstruct them.

The message is not obvious because we don't have a quantitative measure of the benefits and the costs, including foregone opportunities, of maintaining and reconstructing all coastal ecosystems. One can advocate the preservation or reconstruction of coastal ecosystems - all of them, and regardless of costs - only by assuming that they have effectively infinite benefits.

If protection against disasters has infinite value we should not stop at maintaining and reconstructing coastal ecosystems. We should invest enormous (just a little less of infinite) resources in designing and erecting protections that are even more effective than natural ecosystems.

Actually, protection against disasters has, like everything else, finite value. Moreover, at the margin this value is effectively zero.

Barriers and poverty

In a comment to a recent post biodiversivist asks for examples of how poor countries would benefit from eliminating barriers to trade. Barriers separating peaceful people are always harmful. The free exchange of goods, services and ideas enriches people.

The best examples of poor countries getting rich thanks to trade are... the rich countries.

Statistical mechanics

Chris Anderson says that Wikipedia, Google, the blogosphere, markets and biological evolution are systems that "operate on the alien logic of probabilistic statistics, which sacrifices perfection at the microscale for optimization at the macroscale."

[N]obody's in charge; the intelligence is simply emergent. These probabilistic systems aren't perfect, but they are statistically optimized to excel over time and large numbers. They're designed to scale, and to improve with size. And a little slop at the microscale is the price of such efficiency at the macroscale.

But how can that be right when it feels so wrong?

His answer is that it is conterintuitive. He speculates that our "mammalian brains" have difficulty coping with it. Muck and Mystery suggests that the problem is not in our evolved brain but in our culture.

Habitat area and species extinction

Larger areas harbor more species. For some groups of species and types of habitats species-area curves are so well documented that they allow us to predict the number of species in an unstudied area only by knowing its size.

Species-area curves also allow us to guess how many species disappear from a given region when human activities reduce the size of suitable habitat.

For example, using this method E. O. Wilson estimated that 50% of tropical rainforest species will disappear with each 90% loss of forest area.

But…

First,

If most populations were originally globally rare but locally abundant, then depending on how the fragmentation process proceeds, many populations would remain abundant if local patches were protected. If enough of these patches were protected, then global species richness would not decline as much as predicted.

This is from a study by Brian Wilsey, Leanne Martin and Wayne Polley published in the current issue of Conservation Biology. They studied the effect of habitat heterogeneity on species richness in a set of prairie fragments in Iowa, where humans have converted 99.9% of the original prairie area to other uses. They found that there are more native plant species (491) than models of uniformly distributed species predict (27–207). "Even tiny remnants continued to support a large number of native species."

Second, species-area curves tell us nothing about the time dimension. Some populations may dwindle to extinction for a long time. Aveliina Helm, Ilkka Hanski and Meelis Pärtel found that the current number of habitat specialist plant species in 35 calcareous grasslands (alvars) in Estonia reflected not the current sizes of their habitats but those of 70 years ago, before 70% of alvar area disappeared due to changes in land use (published in the current issue of Ecology Letters).

We estimated the magnitude of extinction debt at around 40% in individual alvars, corresponding to predicted loss of around 20 vascular plant species per alvar in the future. With current landscape structure, many of these species will be lost from the entire region, although this will be an even slower process than extinction from individual alvars.

If the causes of habitat destruction cease and the ecosystem returns to its original condition populations may recover before going extinct.

Agricultural protectionism in rich and poor countries

From The New York Times (found via Marginal Revolution):

Two World Bank economists, Kym Anderson and Will Martin, concluded that if the world were to dismantle its agricultural protections, most of the benefits for developing countries would come from the reduction of their own systems of farm support. "Liberalization in the rich countries is a good thing, but in my opinion a small thing," said William Masters, a professor of resource economics at Purdue University and an expert on agriculture in Africa. "Poor countries' own barriers are the biggest constraint to their own development."

Global warming of the planet

Found in Algodeque.

Public lands

This is from a news item in Nature:

The problem, says Alfredo Quarto, director of the Mangrove Action Project, Port Angeles, Washington, is that "mangrove areas are remote, usually public lands, available to lease by corrupt officials". Poor fishers and farmers rarely have any land rights and cannot prevent mangroves being cleared for shrimp ponds. "The people who enforce the laws don't live in these areas and can be convinced by someone with money to turn their backs on the destruction," Quarto says. When the farms collapse, due to disease or contamination, a wealthy owner can move on to another stretch of virgin coast, leaving a useless waste site behind.