Farming in tropical rainforest can preserve biodiversity, ecological service and bring incomes

For the first time a large, truly multidisciplinary team of scientists has studied the complex tradeoffs between incomes for poor farmers in the tropics, biodiversity loss and the way ecosystems cope with deforestation. The results are interesting in the context of biofuel production in the tropics. They show that while conversion of tropical forest for agriculture results in significant declines in biodiversity and carbon storage, farming cash crops such as cacao under the partial shade of high canopy trees can provide a way to balance economic gain with environmental considerations.

The team consisted of a dozen scientists from mainly German universities, in particular the Georg-August-Universität Göttingen, the University of Hohenheim and the University of Bayreuth. Other researchers were from the Bogor Agricultural University and the Tadulako University, both in Indonesia, and from the Catholic University of Leuven, Belgium. Results are published in the current issue of the Proceedings of the National Academy of Sciences.

Losses of biodiversity and ecosystem functioning due to rainforest destruction and agricultural intensification are prime concerns for science and society alike. Potentially, ecosystems show nonlinear responses to land-use intensification that would open management options with limited ecological losses but satisfying economic gains. However, multidisciplinary studies to quantify ecological losses and socioeconomic tradeoffs under different management options are rare. The group of scientists from the social sciences (cultural anthropology, sociology and economics) and plant biologists therefor joined forces to evaluate opposing land use strategies and their socioeconomic outcomes in a focused case-study.

Their object of research was the cacao agroforestry system as it is commonly found in Sulawesi, Indonesia. Field studies were conducted at the margins of Lore Lindu National Park (LLNP) in Central Sulawesi. Sulawesi, an island east of Borneo and northeast of Bali and Java, has high levels of endemic biodiversity which is increasingly threatened by deforestation.

The researchers used data on species richness of nine plant and animal taxa, six related ecosystem functions, and on socioeconomic drivers of agroforestry expansion. Interestingly, they also took into account rarely considered cultural factors, such as culturally driven expectations about risk and wealth that go far beyond rational economics or the analysis of pure market forces. These cultural factors played a big role in the expansion of cacao cultivation by 230% in the last two decades.

The results of the study indicate the following:
biomass :: bioenergy :: biofuels :: energy :: sustainability :: ecosystem :: deforestation :: biodiversity :: agroforestry ::

• Transformation from near-primary forest to agroforestry had little effect on overall species richness, but reduced plant biomass and carbon storage by approximately 75% and species richness of forest-using species by approximately 60%.
• In contrast, increased land use intensity in cacao agroforestry, coupled with a reduction in shade tree cover from 80% to 40%, caused only minor quantitative changes in biodiversity and maintained high levels of ecosystem functioning while doubling farmers' net income.
• Unshaded systems further increased income by approximately 40%, implying that current economic incentives and cultural preferences for new intensification practices put shaded systems at risk.

"We found that a soft intensification of agroforestry that decreases canopy cover by shade trees from 80% to 40%, will double the farmers' income while leaving biodiversity and ecosystem services on a similar level," Dr. Teja Tscharntke, a co-author of the paper and a professor of agroecology at University of Goettingen. "This is an example of a win-win or small loss-big gain situation that we need more to identify sustainable conservation strategies."

The researchers say that while the environmental payoffs of shade-grown cacao are evident, economic incentives are needed to encourage this style of farming. They note that premium "shade-grown" coffee could serve as a model to generate higher income for farmer using agroforestry techniques. Steffan-Dewenter and colleagues add that education and awareness campaigns could further the cause.

"Encouragement of cultural preferences for shaded cacao agroforestry systems and education of local farmers about unappreciated ecosystem services provided by shaded systems could further promote the implementation of certification schemes," the authors write. "Such market-based incentives will crucially determine whether shaded agroforestry systems remain important refugia for tropical biodiversity and sources of essential ecosystem services."

"These findings are the result of fruitful collaboration among ecological and socioeconomic groups and among Indonesian and German researchers," added Tscharntke. "The key was to identify the drivers and effects of land use. From this we were able to develop concepts of sustainable land use."

The scientists conclude that low-shade agroforestry provides the best available compromise between economic forces and ecological needs. Certification schemes for shade-grown crops may provide a market-based mechanism to slow down current intensification trends.


Biofuels and agroforestry
The results are particularly useful for sustainable biofuel projects that rely on agroforestry, instead of on monocultures and/or deforestation. Several research efforts are underway to study the feasibility of making fuels out of non-plantation forestry products - such as oil seeds harvested in pristine rainforests. For an example of these efforts we refer to a pilot project in Brazil based on utilising wild babassu nuts.

According to the researchers of this project, there is a large potential for energy production from the shells of these nuts (up to 260 MW of biomass energy for poor forest communities). Babaçu is a palm tree native to Brazil, widely grown there and provides an important industrial and economical resource because of the oil extracted from the kernels.

The oil is similar to coconut oil and is gradually conquering that market. Since the trees are not grown in plantations, but are used as they stand in the wild (in the Amazon), its nuts are harvested manually by some of Brazil's poorest communities. They are often left with huge waste-streams of shells after they have removed the oil-rich kernels (which is done manually as well). Unicamp's Faculty of Mechanical Engineering studied the potential for using this waste in efficient co-generation plants, and sees a great opportunity in it for rural electrification. Each year, some 2.9 million tons of babassu shell are wasted (earlier post, scroll down).

Similar projects are underway in Cameroon (involving oil-rich Karité nuts) and Gabon, whereas in China, perennial crops like Jatropha curcas are studied for their reforestation capacity as well as their potential to act as shade-crops for legumes in intercropping systems. In such systems (not a typical agroforestry system since it involves new forests), the jatropha trees would function as carbon sinks, their seeds would provide biodiesel feedstocks, and the shade would protect legume cultures. The idea is to create integrated systems that can be managed by smallholders (earlier post).

More information:
Ingolf Steffan-Dewentera, et al, "Tradeoffs between income, biodiversity, and ecosystem functioning during tropical rainforest conversion and agroforestry intensification" [*abstract], PNAS, March 20, 2007 | vol. 104 | no. 12 | 4973-4978.
Mongabay, Farming in the rainforest can preserve biodiversity, ecological services, May 5, 2007.