Desertification: A Walk Through West Africa
Air Date: Week of September 18, 1998
Each year, the world loses more grasslands, croplands and even forests to encroaching deserts. Desertification threatens one-third of the earth's land area, and a billion people in the world's poorer, arid regions. Patrick Gonzalez had a first- hand look at desertification during a five year stay in West Africa. Currently he works for the U.S. Agency for International Development (US AID). Mr. Gonzalez was the first researcher to document a large-scale decline in species richness and tree densities in the West African Sahel in Senegal. To conduct his research he spent a year hiking more than 1,200 miles through west Africa. Steve Curwood talks with Patrick Gonzalez about his long walk.
CURWOOD: It's Living on Earth. I'm Steve Curwood. Each year, the world loses more grasslands, croplands, and even forests to encroaching deserts. Desertification threatens one third of the Earth's land area and threatens a billion people in the world's poorer arid regions. Patrick Gonzalez had a first-hand look at desertification during a 5-year stay in West Africa. Currently, he works for the US Agency for International Development. Mr. Gonzalez was the first researcher to document a large-scale decline in tree diversity and density in the West African Sahel. To conduct his research, he spent a year hiking more than 1,200 miles through Senegal.
GONZALEZ: It's the equivalent of the distance from San Francisco to Dodge City, Kansas. But hiking a long way and looking at the landscape and speaking with local people can tell you a lot about the environmental change.
CURWOOD: So what did your research show? How bad is desertification there in Senegal?
GONZALEZ: My results showed that species richness has declined by one third in the past half of a century. Analysis of aerial photos showed that densities of trees have fallen by one quarter since 1954. Generally, arid Sahel species have moved in from the north as moister species have retracted to the south. The zones have shifted a total of 25 kilometers in just 50 years.
CURWOOD: And with this loss of species, is there a real loss in quality of life?
GONZALEZ: Every species has its own particular uses. Women, for example, depend on 2 particular shrub species for firewood, and these have declined dramatically. There are few fallback species. Twenty-five traditional medicine species have declined dramatically. Eight species that have provided fruits and leaves and gum in times of drought have almost disappeared, so that if a grave famine hit the area in its current condition, the land may not be able to provide the emergency foods that helped people survive in past episodes.
CURWOOD: I'm wondering, what's gone wrong with our aid efforts there? Because we've known about the problems in Senegal, in the Sahel, in West Africa. There have been these series of droughts. The West has poured money in. What's happened?
GONZALEZ: In this area alone, in the past 2 decades, aid agencies have spent $200 million on 47 different projects. Now, the general model has been to use potentially fast-growing species and to raise big nurseries and to plant massive plantations. Unfortunately, these species are fast-growing in their place of origin, in Australia or Latin America, but they're not really adapted to the harsh conditions of the Sahel--so that in my evacuation of the results of all these projects, I found survival rates of less than 18%, and found that they had spent $25 to $50 per surviving tree.
CURWOOD: So they would have been better off doing what, then?
GONZALEZ: Farmers traditionally protect seedlings in their fields. The most valuable seedlings. They prune them, straighten them, raise them to maturity in a practice called "natural regeneration." Natural regeneration requires no special inputs, and it promotes the propagation of well-known, multiple-use species.
CURWOOD: Local species.
GONZALEZ: Local species.
CURWOOD: These plantation plants don't survive in the harsh conditions. Just how harsh is it? How hot does it get there in the Sahel?
GONZALEZ: The sun gets so hot that it'll bleach the back of your shirt white in just a few months. In the village of Injoba Nombatar, where I lived for 2 years, the highest temperature I recorded was 51 Celsius, which is 128 Fahrenheit. That's Death Valley temperatures.
CURWOOD: So, what's the link between desertification and global climate change, do you think?
GONZALEZ: The mechanism is complicated, but the bottom line is that desertification and global warming are locked in a positive feedback cycle. The worse global warming gets, the worse desertification gets. The worse desertification gets, the more vegetation dies, releases carbon dioxide, and exacerbates global warming.
CURWOOD: Now, what does it mean for the people of Senegal and the land's carrying capacity?
GONZALEZ: My research showed that the current population density is 3 times the capacity of the land to sustainably support people.
CURWOOD: Three times the capacity?
GONZALEZ: Three times. The carrying capacity that I calculated was 13 people per square kilometer, but the actual density was 45 people per square kilometer. Now, to give you an idea of what that means, the United States population density is 28 people per square kilometer. So, the population density there is twice that in the United States, so things are starting to get fairly crowded.
CURWOOD: Briefly, what seems to be the impact of that kind of population stress on the land?
GONZALEZ: People are cutting into their capital. The vegetative cover produces a certain amount of usable material every year. That's renewable; it's like the interest of a bank account. If you just take the interest and leave the capital there, then things are fine, things are sustainable. But people are starting to cut into their capital. They're cutting large trees, so that the next year they can't go to that same tree and cut one or two branches that would have re-sprouted. They're also uprooting root crowns of shrubs, so that they cannot go back in the next year and collect firewood from those root crowns.
CURWOOD: Now, you've been working for the US AID. Let's say the phone rings and it is the Minister of the Environment for Senegal. Calls you up, says, "Mr., Dr. Gonzalez, I've read your paper. I want you to solve the problems of desertification in Senegal." What would you tell him?
GONZALEZ: The key is the natural regeneration of local species, not the plantation of exotics. So, I would recommend to him that the government place all of its efforts on the natural regeneration of the vegetation that's already there, and in a broader sense to value local knowledge, and local resources.
CURWOOD: I want to thank you for taking this time with us today.
GONZALEZ: Thank you.
CURWOOD: Patrick Gonzalez is currently an American Association for the Advancement of Science Fellow with the US Agency for International Development in Washington.
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