Small-scale, eco-friendly farms key to preserving tropical biodiversity

Terraced rice paddies, northern Vietnam. Photo: © Tran Thi Hoa / World Bank The ongoing conflict between protecting biodiversity on the one-hand and feeding the world through agriculture on the other, presents perhaps the biggest challenge for conservation.

This tension has caused some to champion agricultural intensification as a way to protect tropical forests. According to the logic behind this approach, intensified farming increases the amount of food we can produce from a given amount of land, which in turn will free up areas that we can restore and protect for biodiversity.

This logic has been used to argue for large-scale, industrial agriculture over small-scale, eco-friendly farming to best support tropical conservation.

However, a new article in the Proceedings of the National Academy of Sciences, presents a compelling counterargument that demonstrates the misconceptions that underlie this logic.

Instead, scientists Ivette Perfecto and John Vandermeer propose an alternative model for conservation in the tropics based on a matrix of small-scale, ecologically friendly farms producing food while providing habitat that complements protected areas. 

A false premise of the agricultural intensification model is that it assumes that increased productivity will lead to an abandonment of inefficient farms in the tropics, migration from rural to urban areas, and the return of farms to forests.

While there is historical precedence for this occuring in North America and Europe, there is not certainty it will occur in tropical areas. In fact, numerous studies from the Tropics show either "no effect or increased deforestation with either agricultural intensification or rural population decline."

The scientists also shoot down a commonly assumed misconception that large-scale industrial agricultural is able to grow more food per acre than alternative approaches.

Perfecto and Vandermeer point to a meta-analysis of 300 studies comparing the yields of organic versus conventional farming methods, which generally found no difference between the two approaches.

Some proponents of agricultural intensification likely confuse the productivity of land use with the profitability of operations. Large-scale, industrial agriculture may be more profitable because it can grow more food with less labor and other inputs.

However the scientists point out that small agriculture may be able to utilize more nuanced farming techniques based on the micro conditions of the property - a level of precision that might not be worth the effort for large-scale operations.

This idea is supported by a study across 15 countries, which found that output per unit area decreased with farm size.

Furthermore, the authors argue that from a conservation perspective, a matrix of small-scale farms across the landscape with ecologically-friendly practices and integrated habitat features will lead to better outcomes for biodiversity than individual large protected areas within a biological wasteland.

The scientists cement their idea within a new theoretical framework, which they term the Matrix Quality Model and present as an alternative to the Agricultural Intensification concept.

Their model is rooted in the idea that persistence of species depends on maintaining metapopulations within a matrix of habitat patches across the landscape.

The authors write, "A new rurality based on the matrix quality approach is more likely to lead to situations in which biodiversity is conserved at the same time that more food is available to those who need it the most."

--by Rob Goldstein

Perfecto, I., & Vandermeer, J. (2010). The agroecological matrix as alternative to the land-sparing/agriculture intensification model Proceedings of the National Academy of Sciences, 107 (13), 5786-5791 DOI: 10.1073/pnas.0905455107