|"You've arrived during the burning season," Bolivian-American agroecologist Daniel Robison told us. "Ten days ago, the sky was full of smoke."
We were in his Jeep, having just arrived in the Amazonian town of Rurrenabaque (or Rurre for short) from La Paz, on our way to our hotel. "What do you think about slash and burn agriculture?" I asked him.
Daniel did something he does a lot, which always confuses me. He did nothing. His face was frozen for a moment, and he said nothing. Was my question stupid? Why? Is slash and burn so obviously horrible (or so obviously wonderful) that I shouldn't have to ask?
Finally he responded. "You'll hear a lot about that from me," he said. He had a presentation he was eager to show our group on that very subject. In retrospect, I don't think he was trying to make me feel stupid. He was probably trying to come up with a simple answer to a question that doesn't have one.
Daniel grew up in Bolivia and then went to college in the U.S. and in the U.K. He's focused on tropical agroecology since graduate school, and today he and his wife own a farm in Rurrenabaque. They are both consultants, mostly focusing on long term planning for sustainable land use in and around Bolivia's protected areas. He called his presentation "Where the Andes Meets the Amazon," explaining it as follows:
This is Rurre. It's the absolute last range of the Andes and if we look in that direction, you don't hit any more hills until the Brazilian border and basically the height difference between the top of the mountain here and the town is less than the height difference between the town and the mouth of the Amazon, which is about 4000 miles away.
Daniel went on to give an agroecological definition of farming:
At its most basic level, agriculture is the complex process of turning the energy of the sun into the energy (plus nutrients) needed by 6.39 billion humans to live, move, think, work, play.
Energy enters ecosystems from the sun by means of photosynthesis, and matter-energy passes through ecosystems in food chains, whereby organisms consume other organisms and are in turn consumed through respiration, waste excretion, and other processes.
When you accept that... then you see that there are possible ecological limits to ecosystem productivities. In other words, every ecosystem that produces food, to a certain extent, is an agroecosystem, and there are limits... The ecosystem has natural limits, when a population or combination of populations reaches the limits imposed by the ecosystem, its numbers must stabilize, or failing that will decline from disease, strife, starvation, low reproduction and so on.
The abiotic limits [are] light, heat, air, water, and nutrients.
At this point he applied this to the Amazon, saying that there's no limit of air, heat, or water in the Amazon. There's a competition for nutrients and light.
In this ecosystem, you never have cold. The temperature never limits crop growth in this environment. Now there are times when water is limiting, but generally speaking, the main limits in this kind of environment are first nutrients, and if you have plenty of nutrients, then it's competition for light. And we're gonna see that in agroforestry systems.
Now, a basic ecological premise: the closer an ecosystem mimics the natural vegetation, the more sustainable it can be. In other words, if your natural vegetation is a savanna, then the closer your farming system mimics the natural functions of a savanna, the more possibility it has of being sustainable. If you're in a forested area, the more your system mimics a forest then the more likely it is to be sustainable. There are obviously exceptions to it but it's a kind of a basic premise of agroecology.
Now, possible social limits to productivity... knowledge... here in the Amazon, if you look at deforestation... basically if you take any country in the Amazon basin... all of the countries are right at about 15 percent deforestation of their Amazon parts... All of them are between 15 and 20 percent. There's much higher percent in terms of lumber being taken out, but in terms of the forest cover being removed, it's about at 15 percent.
On the farm, I work with people who are Tacana Indians. And what I see is that they are about 60 years old, and what they know about the ecosystem is about 10 times what their children know. The children have gone to school. They've got a high school diploma. But what they know about the ecosystem is a fraction of what their parents know. And the knowledge about the Amazon is gonna die out in my lifetime... most of it. The forest is gonna be there a lot longer than the knowledge, the basic knowledge about it from indigenous people.
Daniel also listed some other social limits to productivity: markets, health (of the farmer), and access to land and/or water.
Then he turned his talk to the Amazon. The two main land uses he spoke of are slash and burn agriculture, also known as shifting cultivation, and cattle ranching.
History of the Region
The human presence in the area we were visiting began at least 3000 years ago. Daniel broke down the basic historical periods in the area as follows: Pre-Hispanic (before 1535), Colonial (1535-1825), and the Republic, beginning in 1825. Gold seekers showed up first during the Colonial period, then left. Catholic missionaries showed up in 1620. Daniel believes that the area was populated in the pre-Hispanic period, but then the diseases that the Spanish brought killed off much of the population, making it seem largely uninhabited. Due to disease, the population stayed low until the middle of the 20th century, when Daniel's parents came to Bolivia as missionaries.
During the Colonial period, the Catholic missions would bring in groups of Indians to teach them about Jesus, and as a result, there was a mixing of indigenous languages. Tacana, the language of the indigenous community we would visit the next day, came into existence after 1535, as a mixture of other, older indigenous languages.
Bolivia became a Republic in 1825, and that's when the economic booms began. "The history of the Amazon as a whole," said Daniel, "is a history of economic booms." He describes them as follows:
Basically, all of the population of an area becomes dedicated to an activity that is lucrative. And that activity continues either until the resource is wiped out or the price drops, for one reason or another.
Prior to 1880, quinine was Bolivia's #2 product (after silver). It comes from the bark of a South American tree. Daniel described how the quinine boom worked: A rich person in a town like La Paz would form a relationship with maybe two or three store owners in Rurrenabaque. The store owners in Rurrenabaque would own whatever was needed to go gather quinine. They'd in turn make a deal with poor indigenous people, promising to advance them supplies to gather quinine, in return for a promise to sell the quinine to them. Of course, they would also set the prices for the supplies they had advanced the Indians as well as the quinine they purchased. And they made darn sure that the Indians were constantly in debt.
This system stayed in place, no matter which boom took over. The quinine boom ended when the price of rubber rose, making it more attractive than quinine. British rubber plantations in Malaysia ended the rubber boom in 1917. Malaysia was off-limits to the Allies during World War II, so they turned back to Bolivia for rubber and quinine. The U.S. military came to Rurrenabaque then, collecting rubber and trying to keep it away from the Germans. Daniel's list of booms is below.
- Quinine: 1825-1880
- Rubber: 1880-1917
- Mini booms of gold, lumber, and feather: 1917-1940
- Rubber and quinine: 1940-1945
- Mini booms of gold and lumber: 1946-1964
- Quinine: 1964-1970
- Skins and live animals: 1966-1980
- Drug trade: 1978-1982
- Gold: 1982-1987
- Colonization and lumber: 1987-1998
- Tourism: 1999-
Slash and Burn Agriculture
During the booms, there was a minor segment of the population working on haciendas, producing food and alcohol. Also, Daniel added, going way back in history, the main ways to produce food here were fishing, hunting, and slash and burn agriculture. Daniel defined slash and burn, saying:
At its simplest level, it is a system where forest is cut and burned, crops are planted and then the land is allowed to return to forest.
After showing some pictures of examples of slash and burn - and what the burned area looks like ten years later when the forest has reclaimed it - he continued:
Now if you have a lot of land available, it's a really interesting, and they've been able to show repeatedly that where this system is properly practiced, overall biodiversity is actually higher because when you do this, you force succession. [emphasis mine]
Succession the natural sequence of species in an ecosystem once it is disturbed. First a few species come in and they create the right conditions for the next species that can survive there, and then those species move in, creating the right conditions for the next set of species, and so on and so forth, until you get to a climax state.
If you leave a forest and let it go climax, it goes climax and stays climax until there's a disturbance. And so here you are forcing succession.
Then someone asked what he meant by "properly practiced." He answered:
Properly practiced means that you do this - you burn it - you walk away, and within ten or fifteen years, this forest has reaccumulated all of the carbon that you burned off or was lost through respiration or through decomposition. So you didn't have a net carbon loss from this system.
He then told us why someone might NOT practice this properly. It's more or less a question of having enough land. Once population pressures build up and farmers don't have enough land to leave long enough fallow periods, they start leaving their land fallow for shorter and shorter periods. That is when slash and burn does not work.
Daniel described an experiment he did where he examined soils and then compared the yields between them from slash and burn agriculture. He expected that the good soils would have better yields, but instead he found that the yields were about the same. The reason? The farmers leave the good soils fallow for shorter periods of time. They know where the good soils are, and how long they need to leave an area fallow in order to get a decent yield.
Another way to screw up slash and burn is to lose control of your fire and burn areas you didn't meant to burn. That happens. A lot. Daniel estimates that 70 percent of the burning happens via carelessness, and only 30 percent is on purpose.
Then there's the issue of burning pastures. Daniel says most of the smoke and smog in the air comes from burning pastures. Forests burn hot and clean, he says, but pastures do not. And most of the cattle ranchers in the Amazon burn their pastures. (Most of the Amazon that is cleared is used for cattle ranching.)
And then there are the idiots who burn their forest just to claim their rights to the land. The official state policy is that you cannot own land and not use it, a policy intended to prevent people from owning tons of land they don't use while other people are landless and hungry. So some people burn their forests for no reason, just to make sure they don't lose their land.
Daniel's farm, which we visited a few days later, is an experiment in how to practice responsible agriculture and forest management in the Amazon. For now, the long story short is that slash and burn agriculture can be a very good thing, but often the reality on the ground in the Amazon is not so good. There's also a human question - which I have not addressed here. It's one thing to want to save the rainforest (as we all do) but asking a poor, historically oppressed population to take an economic hit in order to do that isn't necessarily fair. So how do you stay fair to the people who live in the Amazon and protect the rainforest at the same time?