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Agriculture & Land Use Forum exists to answer the question of how to produce enough food and fuel while also conserving the world’s forests.

Paul Spraycar
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October 18, 2011
12:34 PM
468 views

4 big ideas for global agriculture

by Paul Spraycar in Agriculture & Land Use Forum

In a much anticipated study published this month in Nature, Jonathan Foley and colleagues describe the environmental and human impacts of today's agricultural systems, and they identify four big ideas for solving these problems on a global scale.

1. Freeze the land footprint of agriculture:

"The food production benefits of tropical deforestation are often limited, especially compared to the environmental damages accrued... Agricultural production potential that is 'lost' by halting deforestation could be offset by reducing losses of productive farmland and improving yields on existing croplands."

2. Improve yields:

"The best places to improve crop yields may be on underperforming landscapes, where yields are currently below average... There are significant opportunities to increase yields across many parts of Africa, Latin America and Eastern Europe, where nutrient and water limitations seem to be strongest. Better deployment of existing crop varieties with improved management should be able to close many yield gaps, while continued improvements in crop genetics will probably increase potential yields into the future... If yields for these 16 [food and feed] crops were brough up to only 75% of their potential, global production would increase by 1.1. billion tonnes, a 28% increase... Closing yield gaps without environmental degradation will require new approaches, including reforming conventional agriculture and adopting lessons from organic systems and precision agriculture."

3. Increase the efficiency of agricultural inputs:

"Our analysis reveals 'hotspots' of low nutrient use efficiency and large volumes of excess nutrients... We also find that only 10% of the world's croplands account for 32% of the global nitrogen surplus and 40% of the phosphorus surplus. Targeted policy and management in these regions could improve the balance between yields and the environment. Such actions include reducing excessive fertilizer use, improving manure management, and capturing excess nutrients through recycling, wetland restoration and other practices."

4. Shift diets and reduce waste:

"We estimate the potential to increase food supplies by closing the 'diet gap': shifting 16 major crops to 100% human food could add over a billion tonnes to global food production (a 28% increase)... Of course, the current allocation of crops has many economic and social benefits, and this mixed use is not likely to change completely. But even small changes in diet (for example, shifting grain-fed beef consumption to poultry, pork or pasture-fed beef) and bioenergy policy (for example, not using food crops as biofuel feedstocks) could enhance food availability and reduce the environmental impacts of agriculture."

And in summary:

"Our analysis demonstrates that four core strategies can - in principle - meet future food production needs and environmental challenges if deployed simultaneously. Adding them together, they increase global food availability by 100-180%, meeting projected demands while lowering greenhouse gas emissions, biodiversity losses, water use and water pollution."

Foley, J., Ramankutty, N., Brauman, K., Cassidy, E., Gerber, J., Johnston, M., Mueller, N., O’Connell, C., Ray, D., West, P., Balzer, C., Bennett, E., Carpenter, S., Hill, J., Monfreda, C., Polasky, S., Rockström, J., Sheehan, J., Siebert, S., Tilman, D., & Zaks, D. (2011). Solutions for a cultivated planet Nature DOI: 10.1038/nature10452... Read more »

Foley, J., Ramankutty, N., Brauman, K., Cassidy, E., Gerber, J., Johnston, M., Mueller, N., O’Connell, C., Ray, D., West, P.... (2011) Solutions for a cultivated planet. Nature. DOI: 10.1038/nature10452

August 4, 2011
05:51 PM
835 views

Dietary change and bioenergy potential

by Paul Spraycar in Agriculture & Land Use Forum

We’ve now reviewed the impacts of dietary choice on greenhouse gas emissions and on the land area required for global agricultural production. Now we turn to dietary trends and the impact on potential bioenergy production.
A new paper in Biomass and Bioenergy assesses the sensitivity of biomass potential to changes in diets, as well as changes in agricultural yields, cropland expansion, and climate change. The study finds a strong influence of global food requirements, especially the feed required for livestock, on global bioenergy potential.
The researchers developed a biomass balance model to estimate the global supply and demand of agricultural biomass, for which bioenergy competes with food production. To model dietary changes, the researchers developed a “fair and frugal” food consumption scenario involving more equitable food distribution and less meat consumption. In this scenario, only 7-10 percent of global calorific energy would come from animal products (vs. 8-32 percent today).
The “fair and frugal” diet would have a substantial impact on bioenergy potential by increasing it by up to 54 percent. (This scenario also assumes relatively high rates of yield growth.) The study therefore confirms that bioenergy potential, because it competes with land and agricultural products used in livestock production, is highly sensitive to changes in diets.
Haberl, H., Erb, K., Krausmann, F., Bondeau, A., Lauk, C., Müller, C., Plutzar, C., & Steinberger, J. (2011). Global bioenergy potentials from agricultural land in 2050: Sensitivity to climate change, diets and yields Biomass and Bioenergy DOI: 10.1016/j.biombioe.2011.04.035... Read more »

Haberl, H., Erb, K., Krausmann, F., Bondeau, A., Lauk, C., Müller, C., Plutzar, C., & Steinberger, J. (2011) Global bioenergy potentials from agricultural land in 2050: Sensitivity to climate change, diets and yields. Biomass and Bioenergy. DOI: 10.1016/j.biombioe.2011.04.035

August 3, 2011
11:55 AM
755 views

Dietary choice and land use change

by Paul Spraycar in Agriculture & Land Use Forum

We’ve written before about the strong influence of dietary choice on greenhouse gas emissions. A recent study in Agricultural Systems took a look at the land use effects of different scenarios of meat consumption and livestock productivity. The study concludes that a “faster-yet-feasible” growth in livestock productivity, together with a substitution of pork and poultry for ruminant, reduces global agricultural land use about 20 percent, from 5.4 billion ha to 4.4 billion ha in 2030.
Yields of annual crops are usually considered when we talk about meeting the world’s growing demand for food, but this study looks at some hitherto less investigated options: “1) increasing the efficiency of the entire food chain from ‘field to fork’; 2) changing diets toward food commodities requiring less land; and 3) increasing the yields of pastures.”
The researchers use the physical ALBIO (Agricultural Land Use and Biomass) model to study the effects of food consumption trends, livestock and crop productivity, and efficiency in food industry and trade, among others. To model a change in meat consumption, the researchers substitute 20 percent of per capita beef consumption with the same amount of pork and poultry. One step further, the study also models a minor vegetarian transition in regions with high per capita meat consumption (> 70 kg per capita per year). The magnitude of the changes was constrained to keep the results realistic.
The result of the lower-beef scenario is that global agricultural land use in 2030 would fall from 5.4 billion ha to 4.4. billion ha, “mainly due to substantial decreases in permanent pasture area.”

Even though this transition from ruminant meat to pork and poultry is hypothetical, this trend already is taking place to some degree. Moreover, it’s a trend “that could be boosted by upcoming factors, including increasing prices of agricultural land and feedstuffs, and implementation of stricter environmental and climate policies.” However, the scenario in which there is “a partial substitution of vegetable food for meat cannot be motivated by referring to recent trends.”

Wirsenius, S., Azar, C., & Berndes, G. (2010). How much land is needed for global food production under scenarios of dietary changes and livestock productivity increases in 2030? Agricultural Systems, 103 (9), 621-638 DOI: 10.1016/j.agsy.2010.07.005... Read more »

Wirsenius, S., Azar, C., & Berndes, G. (2010) How much land is needed for global food production under scenarios of dietary changes and livestock productivity increases in 2030?. Agricultural Systems, 103(9), 621-638. DOI: 10.1016/j.agsy.2010.07.005

August 3, 2011
11:53 AM
658 views

Indicators for bioenergy

by Paul Spraycar in Agriculture & Land Use Forum

A team of researchers at Oak Ridge National Laboratory provide us this month in Ecological Indicators with a set of indicators that collectively represent how bioenergy systems may affect environmental sustainability. “This suite is intended as a basis or starting point for the selection of indicator suites for particular situations, which may require a subset or expansion of this proposed indicator suite.”
The study seeks to empirically measure environmental effects rather than rely on inferring such effects through assessment of management practices. “Ideally, a comparison between indicator values and baseline conditions should reveal the marginal environmental effects of a bioenergy system.”
The 19 proposed indicators cover six environmental categories:
Greenhouse gases: CO2 equivalent (kg CO2 / GJ)
Productivity: aboveground net primary productivity (g C/m2/yr)
Soil quality: total organic carbon (Mg/ha), total nitrogen (Mg/ha), extractable phosphorus (Mg/ha), bulk density (g/cm3)
Water quality and quantity: nitrate, phosphorus, suspended sediment and herbicide concentrations in streams(mg/L), peak storm flow (L/s), minimum base flow (L/s), consumptive water use (m3/ha/day)
Biodiversity: presence of taxa of special concern (presence), habitat area of taxa of special concern (ha)
Air quality: tropospheric ozone (ppb), carbon monoxide (ppm), total particulate matter (PM2.5 and PM10)
McBride, A., Dale, V., Baskaran, L., Downing, M., Eaton, L., Efroymson, R., Garten, C., Kline, K., Jager, H., Mulholland, P., Parish, E., Schweizer, P., & Storey, J. (2011). Indicators to support environmental sustainability of bioenergy systems Ecological Indicators, 11 (5), 1277-1289 DOI: 10.1016/j.ecolind.2011.01.010... Read more »

McBride, A., Dale, V., Baskaran, L., Downing, M., Eaton, L., Efroymson, R., Garten, C., Kline, K., Jager, H., Mulholland, P.... (2011) Indicators to support environmental sustainability of bioenergy systems. Ecological Indicators, 11(5), 1277-1289. DOI: 10.1016/j.ecolind.2011.01.010

August 1, 2011
03:26 PM
343 views

Future sources of biofuels in the U.S.: Residues from agriculture and forestry

by Paul Spraycar in Agriculture & Land Use Forum

Biomass & Bioenergy just published a review of biomass availability for ethanol production as that industry looks beyond corn for the biomass needed to meet the U.S.’s ambitious ethanol mandate. They estimate that agricultural and forestry residues could only provide 5 percent of current U.S. fuel demand, and even that number assumes all available residues are harvested and converted into biofuels.
The study first describes the two primary conversion technologies – bioconversion and thermochemical conversion – and then concludes that “the two technical platforms have the ability to deliver roughly equivalent fuel outputs based on energy content.”

Bioconversion: Lignin, one of the three polymers in agricultural and forestry residues, is “composed of a number of phenolic compounds that may act as an inhibitor to the hydrolysis and fermentation of sugars.” This requires additional steps beyond the much simpler process required with starch. The main step is hydrolysis, typically carried out by enzymes, which breaks down the cellulosic microfibril structure into its carbohydrate components.
Thermochemical conversion combines several processes to generate synthesis gases (H, CO, CO2, et al.) which can then be reacted over a catalyst to produce biofuels including methanol, ethanol and Fischer-Tropsch fuels.

The study describes a few important feedstock characteristics that influence production yields:

The relative difficulty of bioconversion is dependent upon the chemistry of each particular feedstock. Agricultural residues don’t vary much in their lignocellulosic constituents. For wood residues, interspecies variation in basic chemistry is much more significant.
The difficulty of bioconversion increases as one progresses from agricultural residues to hardwood and then to softwood residues.
Hardwood species (e.g., poplar) have more cellulose and less hemicelluloses than softwoods, which means that greater amounts of glucose are available with hardwoods.
Softwoods (e.g., black spruce) have a thicker and more rigid cell wall, composed of a more recalcitrant form of lignin. Thus, softwoods are the most challenging material for bioconversion.
Although bioconversion of agricultural residues has been show to be ‘easiest,’ sugar contents are lower in agricultural residues when compared to forest residues.
In their natural states, both wood and agricultural residues typically contain about 50 percent water (!).

Agricultural residues include corn stover and straw from other cereal crops (wheat, barley, oats, sorghum, rye, and rice). Annual production is estimated to be 103 million tons of dry material (with a range of 45-118 million tons). Including all these cereal crops extends the range of ethanol beyond the major corn-producing regions and into the “geographic band extending from Alberta and Saskatchewan south to Texas.” States with a large existing ethanol industry, including Iowa, Illinois and Nebraska, have a head start in utilizing these lignocellulosic feedstocks.
For forestry residues, the primary areas of production are in the western and southeast states. The potential annual production from forestry residues is estimated to be from 1.7 to 11.3 hm3 per year, representing between 0.2 and 1.6 percent of current U.S. fuel demand.
The buildout of the lignocellulosic-based industry likely will begin in areas that already have a well-established starch-based industry. It was noted that no thermochemical conversion plants have been built to utilize biomass as a feedstock, though these plants typically require a scale 10 times that of a typical ethanol plant.
Although the overall potential of lignocellulosic biofuels from residue feedstocks is limited – estimated to displace a maximum of 5 percent of current U.S. fuel demand – these feedstocks are the cheapest and most readily available, and may therefore provide a bridge toward the development of a large industry utilizing dedicated energy crops.
Mabee, W., McFarlane, P., & Saddler, J. (2011). Biomass availability for lignocellulosic ethanol production Biomass and Bioenergy DOI: 10.1016/j.biombioe.2011.06.026... Read more »

Mabee, W., McFarlane, P., & Saddler, J. (2011) Biomass availability for lignocellulosic ethanol production. Biomass and Bioenergy. DOI: 10.1016/j.biombioe.2011.06.026

July 21, 2011
02:26 PM
779 views

Beyond corn ethanol: biofuels in the U.S. from switchgrass and miscanthus

by Paul Spraycar in Agriculture & Land Use Forum

If the measure of a story’s importance is whether it makes it into the New York Times, then a new biofuels study in Frontiers in Ecology and the Environment deserves our attention.
The study looks at the impending transition of the U.S. biofuel industry from one based on corn to one using ‘second-generation’ feedstocks. Specifically, the study presents a hypothetical scenario in which all corn-based ethanol is replaced with switchgrass and miscanthus, two promising perennial cellulosic feedstocks. Since 30 percent of corn is currently used to produce ethanol, this study considers the conversion of 30 percent of corn agriculture (about 9 million hectares).
The results: planting cellulosic feedstocks would produce more ethanol, more grain for food, less nitrogen pollution, and fewer greenhouse gas emissions than is produced on the same cropland with corn today.
Even though there is no policy mandate to replace corn grain ethanol with cellulosic sources – the U.S. Renewable Fuel Standard mandates up to 15 billion gallons of corn grain ethanol – productivity (per unit of land area) could be improved with a switch to perennial cellulosic crops. This is the rationale for such a transition from corn to perennial grasses: it could minimize indirect land use change (iLUC) effects “by reducing the land footprint per gallon of ethanol.”
The greenhouse gas reductions are due to “a reduction of fertilizer use as well as increased C sequestration relative to corn,” though soil organic carbon (SOC) accumulation with perennial grasses “is substantially reduced with annual harvests.”
Reductions in nitrogen pollution are due to lower amounts of fertilizer applied to perennial crops. The total improvement could reduce nitrogen load to the Gulf of Mexico by about 12 percent.
In addition to these environmental benefits, a switch to miscanthus could also increase by 83 percent the amount of biomass harvested for bioenergy. This is equivalent to about 12 billion gallons of ethanol.
For background, switchgrass is a native grass that’s grown without fertilizers on Conservation Reserve Program lands. Miscanthus is a sterile hybrid of two grasses native to Asia, and can be high-yielding even without N applications.
Davis, S., Parton, W., Del Grosso, S., Keough, C., Marx, E., Adler, P., & DeLucia, E. (2011). Impact of second-generation biofuel agriculture on greenhouse-gas emissions in the corn-growing regions of the US Frontiers in Ecology and the Environment DOI: 10.1890/110003... Read more »

Davis, S., Parton, W., Del Grosso, S., Keough, C., Marx, E., Adler, P., & DeLucia, E. (2011) Impact of second-generation biofuel agriculture on greenhouse-gas emissions in the corn-growing regions of the US. Frontiers in Ecology and the Environment, 2147483647. DOI: 10.1890/110003

July 13, 2011
01:19 PM
842 views

Bioenergy feedstock choices and landscape dynamics

by Paul Spraycar in Agriculture & Land Use Forum

Though the media clamor for a simple answer to the question ‘Are biofuels a good idea?’, ultimately depends on many factors: choice of feedstock, land use practices, where biofuel cultivation is sited, the scale of overall biofuel production and its effect on global energy and commodity prices, and so on. In other words, it’s complicated.
A new paper from researchers at Oak Ridge National Laboratory, appearing in Ecological Applications in June 2011, explores the complex land management decisions and bioenergy production systems that affect biofuel sustainability. The researchers conclude that, despite all the existing research documented on Agriculture & Land Use Forum and elsewhere, additional quantitative and qualitative measures are needed to adequately assess bioenergy feedstock choices for renewable liquid fuels. What’s needed is a “holistic” approach that considers “the complete bioenergy system from the feedstock production to transport, conversion, production, and market delivery within larger landscape dynamics.”
The analysis focused on the potential of lignocellulosic feedstock options, given their numerous environmental benefits and energy replacement advantage over corn grain ethanol. These feedstocks include: municipal wastes; agricultural residues such as corn stover and sugarcane bagasse; dedicated energy crops such as perennial grasses and fast-growing tree species; and wood residues from logging and fuel treatment.

Socioeconomic effects: The researchers downplay the adverse effects of biofuel production on global food prices, based on the myriad factors (e.g., high overall energy prices, previously low prices that led to falling stocks, bad weather, and speculation) that led to the 2008 food price crisis. USDA research attributes less than 1 percent of food price increases to biofuel production. Moreover, “expanded corn and sugarcane productivity [resulting from more biofuel production] offers more flexibility to adjust to temporary shocks and thereby to provide more stable prices for producers and consumers alike.”
Implications of biofuel choices across scales: The authors note the need for a comprehensive view of biofuels’ impacts, and highlight hypoxia as an example of a regional impact resulting from local biofuel production and land use management. Indicators must capture these effects in addition to the on-site effects. Many studies have shown that tree crops and perennial grasses maintain or reduce sediment and nutrient runoff when compared with annual crops.
Indirect land use change: Greenhouse gas emissions are a significant determinant of bioenergy sustainability, but data and measurement systems are fraught with uncertainty. The authors focus in particular on research quantifying the greenhouse gas emissions from indirect land use change (iLUC) and, in general, they downplay the negative effects from iLUC, mainly due to the fact that “land-use changes and associated carbon emissions are much more complex than portrayed in the models used to infer indirect land-use effects… to date, there are no models that capture these influences.”
The paper concludes by emphasizing the complexity of the issues affecting biofuel sustainability and the need for “a systematic approach to understand the interactions between different implications and other forces affecting bioenergy production and land-use changes. Models need to include key processes affecting land-use and management choices and should be validated and tested against empirical data. Information needs to be collected on the causes and effects of land-use change, in general, and bioenergy feedstock choices, in particular. Much of the information needed is at watershed and regional scales, where data is often sparse but benefits of bioenergy options may be high. Furthermore, sustainable ways to address bioenergy needs will be place-based and depend on specific crop and management decisions as well as on the context (soils, past land-use practices, adjacent land uses, policy options and constraints, prevailing air and water quality, etc.).”
Dale, V. et al. (2011). Interactions among bioenergy feedstock choices, landscape dynamics, and land use Ecological Applications, 21 (4), 1039-1054... Read more »

Dale, V. et al. (2011) Interactions among bioenergy feedstock choices, landscape dynamics, and land use. Ecological Applications, 21(4), 1039-1054. info:/

July 11, 2011
07:20 PM
683 views

Biofuels and indirect land use change: from hunch to causal connection

by Paul Spraycar in Agriculture & Land Use Forum

In the realm of biofuels and indirect land use change, policy-makers face a dilemma: how to account for a consequence of biomass cultivation that is almost certainly a problem but is very hard to measure. That consequence is indirect land use change, when land biomass production displaces agriculture and other land uses to other places. If those alternative uses shift to land with high carbon stocks, the effect is large greenhouse gas emissions that may wipe out any GHG benefits the biomass production promised in the first place.
As Erik Gawel and Grit Ludwig write in Land Use Policy, the iLUC accounting methodologies are in their infancy. The issues that impede improvements center around the difficulty of causal attribution of land use change to bioenergy production. Attributing particular land use changes to a particular bioenergy system requires numerous assumptions at multiple spatial and temporal scales. Even when such attribution would be possible, policy-makers must then decide how to regulate such development. Given that iLUC transcends political boundaries, such policies must account for international trade considerations, including trade partners with weak governance systems.
Current approaches for governing bioenergy and iLUC
Impact-related approach: treats indirect land use change as direct effects, making observation and regulation more practical.
Product assignment approach: attempts to internalize iLUC effects into certain bioenergy products. This may be modeled directly or denoted by an iLUC factor or ‘adder’ that assigns a certain level of GHG emissions to all land uses.
General governance approach: assumes that the two are impractical and adopts a more generalized sector-wide policy focus. This includes the option to ‘lower pressure’ by “dimininishing the demand for biomass as agricultural or silvicultural product. Mechanisms are the reduction of targets and quota, feed-in tariffs and user obligations for biofuels for certain or for all production pathways or bioenergy.”
Policy recommendations
These approaches vary in terms of their environmental performance and political feasibility. Based on an analysis of each approach, the authors conclude that “there is no predominant method that performs well, is also practicable, available and finds general societal consensus.” The approaches each have their own failings, from complexity to lack of transparency to lack of global applicability.
Even so, the authors identify the ‘lowering pressure’ approach is the most practical, available and effective option. This implies that policy-makers would “diminish bioenergy targets and choose bioenergy pathways with minor land use conflicts in order to lower the pressure on land use change processes in bioenergy-producing regions worldwide.”
Gawel, E., & Ludwig, G. (2011). The iLUC dilemma: How to deal with indirect land use changes when governing energy crops? Land Use Policy, 28 (4), 846-856 DOI: 10.1016/j.landusepol.2011.03.003... Read more »

Gawel, E., & Ludwig, G. (2011) The iLUC dilemma: How to deal with indirect land use changes when governing energy crops?. Land Use Policy, 28(4), 846-856. DOI: 10.1016/j.landusepol.2011.03.003

July 8, 2011
11:50 AM
835 views

Bioenergy is complicated

by Paul Spraycar in Agriculture & Land Use Forum

Policies that raise carbon prices carry the risk that resulting increases in bioenergy production will displace food production, thereby increasing food prices and generating an additional economic incentive to clear forests.
In an opinion appearing in WIREs Climate Change, Christian Azar weighs some of the risks and concludes that ‘well-performing bioenergy systems’ might be just fine from an environmental and social perspective, but the scale of the potential production does raise some real concerns.
The potential of biomass-based energy is very large, replacing 10 to 20 percent of global energy demand in 2050. Azar emphasizes his conservative back-of-the-envelope calculation of the potential of dedicated bioenergy crops – 500 million hectares providing about 10 percent of 2050 energy demand – over more ‘extreme’ estimates which are many times higher in some cases.
In addition, bioenergy is attractive because it can be an inexpensive way to reduce emissions, and these emissions can even be negative when combined with carbon capture and storage (CCS) technology. Indeed, in a separate study, Azar and others estimated that the cost of reducing global greenhouse gas emissions ‘would drop by more than half, if biomass energy with CCS were included.’
However, some existing bioenergy production systems are thought to be of dubious environmental benefit, and are likely to have been a contributing factor to recent increases in global food prices. The main risks center around the amount of land required to dramatically increase production of biomass-based energy: “For bioenergy from plantations to play an important role in global energy systems, huge areas of land are required,” and there’s a very real risk that this magnitude of land use change will adversely affect forests and other valuable ecosystems.
The author notes that 500 million hectares of dedicated bioenergy crops are needed, which “corresponds to half the size of the United States or one third of the global land currently under cultivation. Achieving such an objective by the year 2060 would require that the area used for bioenergy crops expand by some 10 million hectares every near during the next half century.”
The positive or negative impacts of bioenergy production depend a lot on local circumstances, and policy decisions will determine to a great extent the ultimate effect on climate change and local farming communities. In addition to international climate treaties and certification schemes, the author notes the technical potential of intensified production systems and of dietary changes. Regarding intensification, Azar references recent research by Wirsenius and Burney describing significant historical and future benefits, in the billions of hectares of saved cropland, resulting from agricultural intensification.
Although consumption taxes on high-carbon meat production would be practically and politically difficult, the author also notes that “in the long run it will be intellectually difficult to defend a policy that taxes greenhouse gas emissions from cars and power stations, but not from agricultural production.”
Azar, C. (2011). Biomass for energy: a dream come true… or a nightmare? Wiley Interdisciplinary Reviews: Climate Change, 2 (3), 309-323 DOI: 10.1002/wcc.109... Read more »

Azar, C. (2011) Biomass for energy: a dream come true… or a nightmare?. Wiley Interdisciplinary Reviews: Climate Change, 2(3), 309-323. DOI: 10.1002/wcc.109

June 18, 2011
02:09 PM
883 views

Sizing up the world’s major biofuel crops

by Paul Spraycar in Agriculture & Land Use Forum

With demand for biofuels expected to soar in the coming decades, it’s worth asking whether the environmental benefits of biofuels are really all they’re cracked up to be.
Varied production systems, climates and growing conditions make apples to apples comparisons difficult, but a recent paper, published in Biomass & Bioenergy in January 2010, attempts to answer the question of which biofuel crops are environmentally sustainable.
The analysis considers only commonly used (‘important’) crops already in production. For bioethanol production, the list of crops included maize (U.S.), wheat (Northwest Europe), sugar beet (Northwest Europe), cassava (Thailand), sweet sorghum (China), and sugarcane (Brazil). For biodiesel, they analyzed winter oilseed rape (Northwest Europe), soybean (U.S.), and oil palm (Malaysia).
Researchers developed a method to score each biofuel’s performance in nine different areas: energy yield, energy ratio (to account for soybeans’ high energy yield but low nitrogen inputs), greenhouse gas emissions, soil erosion, soil-borne diseases, nitrogen use efficiency, pesticide usage, and water usage. The factors are weighted equally in the calculation of a single score for each crop. Below are the results for greenhouse gas emissions:

And the winners are: Oil palm (southeast Asia), sugarcane (Brazil), and sweet sorghum (China). The high scores are explained primarily by their “high net energy yields per hectare… which result in good nitrogen use efficiency, pesticide use efficiency and water productivity.”
Coming out in the middle were sugar beet (Northwest Europe), cassava (Thailand), rapeseed (Northwest Europe), and soybean (U.S.). Maize (U.S.) and wheat (Northwest Europe) performed worst in nearly all indicators, including the main goal of these biofuels: “reduction of fossil energy use and GHG emissions.”
The authors suggest that because the tropical crops are so productive, “it may be more sustainable and economically sound for countries in the North to import biofuels from, e.g. Brazil or South East Asia.”
A big caveat, of course, is that this analysis does not include indirect land use change (iLUC), which often can be the difference between a good (GHG-reducing) and a bad (GHG-increasing) biofuel. Indeed, iLUC is a huge concern for two of the ‘winning’ biofuels (oil palm and sugarcane), given their links to deforestation in southeast Asia and Brazil, respectively. The study also did not economic and social sustainability, or the impacts on biodiversity.
Another caveat, according to the researchers, is that “estimates of energy consumption and GHG emissions generally varied widely for all crops, demonstrating that there is still little consensus among authors in this respect.”
de Vries, S., van de Ven, G., van Ittersum, M., & Giller, K. (2010). Resource use efficiency and environmental performance of nine major biofuel crops, processed by first-generation conversion techniques Biomass and Bioenergy, 34 (5), 588-601 DOI: 10.1016/j.biombioe.2010.01.001... Read more »

de Vries, S., van de Ven, G., van Ittersum, M., & Giller, K. (2010) Resource use efficiency and environmental performance of nine major biofuel crops, processed by first-generation conversion techniques. Biomass and Bioenergy, 34(5), 588-601. DOI: 10.1016/j.biombioe.2010.01.001

May 4, 2011
04:54 PM
738 views

Top research priorities: agriculture and land use

by Paul Spraycar in Agriculture & Land Use Forum

This month’s BioScience includes a list of the top 40 opportunities for science to inform U.S. conservation and management policy. In this article, co-written by 7 lead authors who interviewed several dozen experts, “questions or issues were not identified primarily by researchers but by scientifically oriented individuals responsible for development and implementation of policy and funding of research.”
Several of these (U.S.-focused) research questions are relevant to this site’s (global) exploration of agriculture and land use:

How do different strategies for growing and harvesting biomass or biofuel affect ecosystems and associated social and economic systems?
How do different strategies for managing forests, grasslands, and agricultural systems affect carbon storage, ecosystem resilience, and other desired benefits?
What are the relative ecological effects of increasing the intensity versus spatial extent of agricultural and timber production?
What are the potential effects on ecosystems of developing new sources of renewable and nonrenewable energy?
How do demographic and cultural shifts in the human population of the United States shape conservation values, attitudes, and behaviors?
How do shifts in agricultural subsidies, commodity prices, and markets affect the location and rate of conversion of natural ecosystems to agricultural uses?
How does the configuration of land cover and land use affect the response of ecosystems to climate change?
How will changes in land use and climate affect the severity of infrequent, spatially extensive disturbance events?

Fleishman, E., Blockstein, D., Hall, J., Mascia, M., Rudd, M., Scott, J., Sutherland, W., Bartuska, A., Brown, A., Christen, C., Clement, J., DellaSala, D., Duke, C., Eaton, M., Fiske, S., Gosnell, H., Haney, J., Hutchins, M., Klein, M., Marqusee, J., Noon, B., Nordgren, J., Orbuch, P., Powell, J., Quarles, S., Saterson, K., Savitt, C., Stein, B., Webster, M., & Vedder, A. (2011). Top 40 Priorities for Science to Inform US Conservation and Management Policy BioScience, 61 (4), 290-300 DOI: 10.1525/bio.2011.61.4.9... Read more »

Fleishman, E., Blockstein, D., Hall, J., Mascia, M., Rudd, M., Scott, J., Sutherland, W., Bartuska, A., Brown, A., Christen, C.... (2011) Top 40 Priorities for Science to Inform US Conservation and Management Policy. BioScience, 61(4), 290-300. DOI: 10.1525/bio.2011.61.4.9

April 25, 2011
04:36 PM
834 views

Dietary choice a key driver of greenhouse gas emissions

by Paul Spraycar in Agriculture & Land Use Forum

A lot is made of the growth in the world’s population – to 9 billion humans by 2050 – and the need for increased food production to meet higher demand. But a study in Global Environmental Change, published in February 2010, shows that diet may be an even more important factor in determining the scale and scope of food production requirements.
To address the wide range of estimates for future agricultural production, the study’s authors used a spatially explicit model (Model of Agricultural Production and its Impact on the Environment – MAgPIE) to derive land use patterns based on economic and biophysical conditions.
In the baseline scenario, in which the share of animal products in human diets does not change (but per capita calorie intake does increase), agricultural emissions increase 64 percent (to 8690 Mt CO2-e).
The ‘increased meat scenario’ increases GHGs by 76 percent relative to the baseline. This scenario assumes that food energy demand and the share of livestock products in total caloric intake increase with GDP:

The ‘decreased meat scenario’ reduces GHGs by 51 percent relative to the baseline. In other words, the majority of the baseline increase in agricultural emissions would be offset by a shift to less meat-intensive diets. In this scenario, the assumption is that demand for meat products could somehow be reduced 25 percent per decade. Reduced emissions from meat production (enteric fermentation, manure management) are partially offset by small increases in N2O soil emissions from (increased) food cropping methane emissions from rice production.
Importantly, technological mitigation – including N application efficiency, manure management, water management in rice cultivation – results in fewer emission reductions than changes in food consumption. In other words, managing emissions from livestock production can reduce emissions, but not enough to offset the emissions caused by a shift to more meat-intensive diets. Thus, “technological mitigation options are not as effective as changes in food consumption.”
The authors also note, however, that efforts to reduce meat consumption for the purpose of reducing agricultural GHG emissions also need to account for the importance of livestock food products as a source of livelihoods as well as protein, especially in places where both economic opportunities and protein are scarce.
Popp, A., Lotze-Campen, H., & Bodirsky, B. (2010). Food consumption, diet shifts and associated non-CO2 greenhouse gases from agricultural production Global Environmental Change, 20 (3), 451-462 DOI: 10.1016/j.gloenvcha.2010.02.001... Read more »

Popp, A., Lotze-Campen, H., & Bodirsky, B. (2010) Food consumption, diet shifts and associated non-CO2 greenhouse gases from agricultural production. Global Environmental Change, 20(3), 451-462. DOI: 10.1016/j.gloenvcha.2010.02.001

April 20, 2011
01:15 PM
1,053 views

Agricultural intensification and deforestation: case study from West Africa

by Paul Spraycar in Agriculture & Land Use Forum

CIFOR reports on its recently published study, co-authored by the International Institute for Tropical Agriculture (IITA) and appearing in Environmental Management, about the benefits of intensified agriculture in West Africa.
The study highlights extensive smallholder agriculture as the "principal driver" of deforestation of the Guinean rainforest, of which only 18% of its original extent remains. Had more intensive agricultural practices been used by cocoa, cassava and palm oil smallholders from 1988 to 2007, 21,000 square kilometers of agricultural expansion (31% of the total expansion) could have been avoided. Thus, efforts to reduce deforestation, including REDD, might be well-advised to address agricultural practices and the their implications for land use change. From CIFOR's blog post:

"Researchers at IITA found that increasing fertilizer use on cocoa-timber farms would have spared roughly 2 million hectares of tropical forest from being cleared or severely degraded. On average, farmers are using less than 4kg of total nutrients per hectare in the region...
REDD funds could be used to incentivise and promote agricultural intensification efforts that would lead to higher rural incomes, greater food security, and avoided emissions through the achievement of higher agricultural yields...
The value of avoided carbon emissions are conservatively estimated at $565 per hectare for achieving the envisaged doubling of yields...
Says Gockowski, "There is a risk that REDD+ interventions will only be implemented within the forestry sector, while extensive low-input agriculture - the fundamental driver of deforestation in West aAfrica and the root cause of most rural poverty - gets neglected. This would be a mistake in tackling global carbon emissions in West Africa."

Gockowski, J., & Sonwa, D. (2010). Cocoa Intensification Scenarios and Their Predicted Impact on CO2 Emissions, Biodiversity Conservation, and Rural Livelihoods in the Guinea Rain Forest of West Africa Environmental Management DOI: 10.1007/s00267-010-9602-3... Read more »

Gockowski, J., & Sonwa, D. (2010) Cocoa Intensification Scenarios and Their Predicted Impact on CO2 Emissions, Biodiversity Conservation, and Rural Livelihoods in the Guinea Rain Forest of West Africa. Environmental Management. DOI: 10.1007/s00267-010-9602-3

April 6, 2011
02:23 PM
821 views

How to increase forest cover and food production at the same time

by Paul Spraycar in Agriculture & Land Use Forum

Countries that have successfully managed a land use transition – simultaneously increasing forest cover and food production – highlight the importance of economic globalization in the availability (or scarcity) of land in the future.
A study published in PNAS documents the policies and innovations that aided these transitions.
Land use zoning and agricultural intensification – two main strategies normally used by countries to manage their land use – may be less effective, according to the authors, in the face of “the acceleration of economic globalization in tandem with a looming scarcity of productive land globally.”
Increasingly, the forces of globalization separate food production from consumption. From 1961 to 2001, cross-border trade in food commodities increased fivefold, and trade in raw wood products increased sevenfold.
Despite all the downsides, global trade also has the potential to increase global land use efficiency through the comparative advantages of regional specialization. Depending on how efficient and orderly this allocation of land uses occurs, “the current land reserve could be exhausted by as early as in the late 2020s and at the latest by 2050.”
The authors highlight the experience of a handful of ‘forest transition’ countries – China, Costa Rica, El Salvador and Vietnam – where forests expanded but did not encroach on agricultural land (agricultural production also expanded). Instead, the forest expansion took place on degraded lands. In these countries, “the apparent tradeoff between forest and agriculture can be minimized through spatial management and the use of degraded or low competition lands.”
In the future, innovations are likely needed to avoid the global land shortage that might occur in the more pessimistic projections:

Technological breakthroughs: genetically modified crops or second generation biofuels
Investments in restoration of degraded lands
Adoption of more vegetarian diets in rich countries
Strict land use planning to preserve prime agricultural land
New industrial processes to produce synthetic food, feed and fibers

“Absent such innovations, humanity could inadvertently cross a threshold where annual increments in global food production beyond yield increases would lead to an accelerating conversion of natural forests, with detrimental environmental impacts, and to cropland expansion on unsuitable lands, therefore requiring large capital investments, intensive use of water and fertilizers, and a much larger area for any increment in production.”

Lambin, E., & Meyfroidt, P. (2011). Inaugural Article: Global land use change, economic globalization, and the looming land scarcity Proceedings of the National Academy of Sciences, 108 (9), 3465-3472 DOI: 10.1073/pnas.1100480108... Read more »

Lambin, E., & Meyfroidt, P. (2011) Inaugural Article: Global land use change, economic globalization, and the looming land scarcity. Proceedings of the National Academy of Sciences, 108(9), 3465-3472. DOI: 10.1073/pnas.1100480108

April 3, 2011
06:03 PM
872 views

A conservative estimate of bioenergy potential (which may still be too high)

by Paul Spraycar in Agriculture & Land Use Forum

How much bioenergy can be produced without displacing food production and the world’s forests? The qualified answer is 15 to 25% of the world’s energy demand in 2050, according to a study just published in GCB Bioenergy.
This figure is on the lower end of recent studies of the world’s bioenergy potential, which tend not to consider water scarcity and other constraints. Ineed, this conservative estimate may still be high considering the land use change (double the rate of global cropland expansion) and irrigation (double today’s freshwater use for irrigation) that would be required to produce this much bioenergy.
Bioenergy production is considered an important part of efforts to meet the ‘2 degree’ target for climate change mitigation. As well, if done correctly, producing bioenergy could be an economic development tool in rural areas (in both developed and developing countries). However, large expansions of biomass cultivation could contribute to the loss of forests and biodiversity. Moreover, the carbon debt created by cutting down forests could take up to 100 years to be compensated by greenhouse gas savings from biofuels.
This study seeks to improve on past estimates of global bioenergy potential by introducing environmental and agricultural constraints. The study “follows strictly a food first paradigm,” in which “land currently used for food and fiber production will not be available for food and fiber production.” The study accounts for biodiversity by excluding a certain share of natural areas from biomass cultivation in order to conserve hotspots of biodiversity and valuable wilderness areas.
They used a model of plant growth to determine what crop yields could be achieved under different climate, soil and management conditions (note that this is probably more accurate than simply extrapolating from isolated field trials). Biomass sources (feedstocks) include residues from agriculture and forestry, organic wastes, surplus forestry, and energy crops. While dedicated energy crops – in this study, these included trees (poplars, willows) and grasses (miscanthus, switchgrass) – are usually considered the most controversial from an environmental impact standpoint, removing agriculture and forestry residues also can disrupt soil quality, crop productivity, and the health of forest ecosystems.
To achieve these levels of production by 2050, it would require an average of 10-30 million hectares of new plantations each year. This rate is about double the rate of agricultural expansion in the last 50 years. This high rate of expansion may be unrealistic, given the infrastructural and institutional constraints.
BERINGER, T., LUCHT, W., & SCHAPHOFF, S. (2011). Bioenergy production potential of global biomass plantations under environmental and agricultural constraints GCB Bioenergy DOI: 10.1111/j.1757-1707.2010.01088.x... Read more »

BERINGER, T., LUCHT, W., & SCHAPHOFF, S. (2011) Bioenergy production potential of global biomass plantations under environmental and agricultural constraints. GCB Bioenergy. DOI: 10.1111/j.1757-1707.2010.01088.x

March 23, 2011
03:44 PM
847 views

Bioenergy: how much can the world produce by 2050?

by Paul Spraycar in Agriculture & Land Use Forum

Estimates of the world's technical potential to produce bioenergy vary widely – by a factor of almost 50.
What explains such a wide range? That’s the subject of a recent analysis that appeared in Current Opinions in Environmental Sustainability in November 2010.
The authors reviewed recent literature to understand the different assumptions that affect these estimates:

Future yields of food and energy crops: yield expectations vary widely (by a factor of 9). One study argues forcefully that yield assumptions have been over-estimated by more than 100%.
Feed conversion efficiencies in the livestock system.
Land suitability and availability: projected areas for bioenergy crops range from 0.4% to 28% of the world’s ice-free landmass.

To resolve these issues, the authors recommend the following:

Pay attention to the studies that “consider critical social (e.g., food production) and environmental (e.g., biodiversity conservation) goals,” which will exclude many areas from biomass cultivation, while also considering more than just abandoned farmland, which “neglects the possibility that other land could become available through intensification or land conversion.”
Look for consensus (when different analytical approaches reach the same result): In identifying three studies that all point to a global bioenergy potential near the midpoint of the wide range of estimates, the authors point to this as informative because the studies “are based on completely different, complementary methods and yet still arrived at largely similar results that are plausible…”

The authors sum up the global bionergy potential this way:

Dedicated energy crops (midpoint of middle-of-the-road estimates: 81 EJ per year
Crop residues, animal manures, municipal solid wastes: 100 EJ per year
Forestry residues (arithmetic mean of estimates): 27 EJ per year
Total: 208 EJ per year (range of uncertainty 160-270 EJ per year)

These calculations represent current knowledge on future bioenergy potential, but the list of remaining uncertainties is long: “the availability and suitability of land for energy crops, the development and potential of yield increases, future area demand for food, conservation and other purposes, trade-offs with other environmental goals (e.g., biodiversity), water availability and climate impacts.”
Haberl, H., Beringer, T., Bhattacharya, S., Erb, K., & Hoogwijk, M. (2010). The global technical potential of bio-energy in 2050 considering sustainability constraints Current Opinion in Environmental Sustainability, 2 (5-6), 394-403 DOI: 10.1016/j.cosust.2010.10.007... Read more »

Haberl, H., Beringer, T., Bhattacharya, S., Erb, K., & Hoogwijk, M. (2010) The global technical potential of bio-energy in 2050 considering sustainability constraints. Current Opinion in Environmental Sustainability, 2(5-6), 394-403. DOI: 10.1016/j.cosust.2010.10.007

March 22, 2011
06:40 PM
876 views

Farmland’s impact on tropical forests in the 1980s and 1990s

by Paul Spraycar in Agriculture & Land Use Forum

Recent news about deforestation in the Amazon has been pretty positive: Deforestation has stabilized since the turn of the century, and Brazil, it seems, is on track to meet its stated goals for reducing deforestation and associated greenhouse gas emissions.
Still, the long-term story is one of significant deforestation, primarily to make room for agriculture. Whether agricultural and biofuels expansion dramatically affects the carbon and biodiversity of the world’s forests will largely depend on how much of this cultivation can successfully be focused on other land types: shrubland, grassland, degraded agricultural land, plantations, and so on.
In the 20th century, it appears we weren’t successful. A 2010 paper in PNAS concludes that the majority of new agricultural land in the 1980s and 1990s intact and disturbed tropical forests.

The numbers are big:

During the 1980s and 1990s, total agricultural land in developing countries increased by 629 million hectares (about the size of Alaska and Texas combined). Developed countries lost 335 million hectares of agricultural land during the same period.
At the turn of the century, Brazil had 13 million hectares of soybeans. Now soybeans cover more than 21 million hectares in the country.
Indonesia’s oil palm production nearly tripled during the last 20 years: from 2 million hectares to 5 million hectares in 2008.
Some estimate that up to 10 billion new hectares of agricultural lands will be needed by 2050.

As global agricultural demand grows, it will be increasingly important where and how food is produced. It’s almost certain that cropland and pasture must expand, but what types of ecosystems they displace will greatly influence the environmental consequences. This study shows that, in the 1980s and 1990s at least, we were not successful in steering development away from forests.
Gibbs, H., Ruesch, A., Achard, F., Clayton, M., Holmgren, P., Ramankutty, N., & Foley, J. (2010). Tropical forests were the primary sources of new agricultural land in the 1980s and 1990s Proceedings of the National Academy of Sciences, 107 (38), 16732-16737 DOI: 10.1073/pnas.0910275107... Read more »

Gibbs, H., Ruesch, A., Achard, F., Clayton, M., Holmgren, P., Ramankutty, N., & Foley, J. (2010) Tropical forests were the primary sources of new agricultural land in the 1980s and 1990s. Proceedings of the National Academy of Sciences, 107(38), 16732-16737. DOI: 10.1073/pnas.0910275107

March 20, 2011
06:23 PM
750 views

Food production causes less deforestation over time

by Paul Spraycar in Agriculture & Land Use Forum

The complex but unmistakable connections between deforestation and agriculture in the tropics is the subject of Arild Angelsen’s contribution to the recent PNAS special issue on food production and climate mitigation in tropical landscapes.
Angelsen examines local policies to discourage extensive agriculture and increase forest protection and management, and how those policies affect forest conversion and, ultimately, global deforestation rates. He concludes that policy-makers must reconcile the local impacts of agricultural intensification at the frontier – which tend to increase forest encroachment – with the regional and global benefits of yield growth, as stipulated by the global food equation. The ‘spatial delinking’ of forests and intensive food production areas will serve to reduce the direct pressure of food production on forest conversion.
To lower agricultural rent, Angelsen suggests policies to promote intensive agriculture, including subsidies that increase the rent of intensive systems. It’s important that these policies serve to increase labor demand and pull that labor out of extensive systems in the area. Otherwise, if these policies lead to mechanization, labor will be freed up for additional extensive cultivation.
In terms of agricultural development in frontier areas, the paper notes that win-win opportunities may only occur where intensive and extensive systems already exist in the same area; in those cases, promoting intensification can lead to less extensive forest-clearing.
Efforts to increase forest rent face a number of obstacles, but may promote forest cover stabilization and re-growth. Whereas in the past forest transition countries have increased the extractive forest rent (e.g., through forest scarcity), in the future protective forest rent, such as through REDD and other markets for public goods, could be the main driver in forest protection.
The paper suggests that, at higher scales, the trade-off between food production and forest conservation is limited: “… Only a small share (<10%) of the agricultural output increase [3.3% per year from 1985-2004] has come from deforestation”

“At the national level, higher volumes of agricultural trade have delinked domestic and local consumption from production and deforestation. Moreover, high rates of deforestation for several decades have made forested areas recede, frequently into relatively inaccessible areas. The issues of forest conservation and agricultural production are becoming increasingly spatially delinked.”

Agricultural intensification efforts, therefore, should “target low-forest areas, or crops and production systems that are unsuitable at the agricultural frontier.”
Angelsen, A. (2010). Climate Mitigation and Food Production in Tropical Landscapes Special Feature: Policies for reduced deforestation and their impact on agricultural production Proceedings of the National Academy of Sciences, 107 (46), 19639-19644 DOI: 10.1073/pnas.0912014107... Read more »

Angelsen, A. (2010) Climate Mitigation and Food Production in Tropical Landscapes Special Feature: Policies for reduced deforestation and their impact on agricultural production. Proceedings of the National Academy of Sciences, 107(46), 19639-19644. DOI: 10.1073/pnas.0912014107

March 20, 2011
06:23 PM
419 views

Agriculture's role in deforestation declines as time goes on

by Paul Spraycar in Agriculture & Land Use Forum

The complex but unmistakable connections between deforestation and agriculture in the tropics is the subject of Arild Angelsen’s contribution to the recent PNAS special issue on food production and climate mitigation in tropical landscapes.
Angelsen examines local policies to discourage extensive agriculture and increase forest protection and management, and how those policies affect forest conversion and, ultimately, global deforestation rates. He concludes that policy-makers must reconcile the local impacts of agricultural intensification at the frontier – which tend to increase forest encroachment – with the regional and global benefits of yield growth, as stipulated by the global food equation. The ‘spatial delinking’ of forests and intensive food production areas will serve to reduce the direct pressure of food production on forest conversion.
To lower agricultural rent, Angelsen suggests policies to promote intensive agriculture, including subsidies that increase the rent of intensive systems. It’s important that these policies serve to increase labor demand and pull that labor out of extensive systems in the area. Otherwise, if these policies lead to mechanization, labor will be freed up for additional extensive cultivation.
In terms of agricultural development in frontier areas, the paper notes that win-win opportunities may only occur where intensive and extensive systems already exist in the same area; in those cases, promoting intensification can lead to less extensive forest-clearing.
Efforts to increase forest rent face a number of obstacles, but may promote forest cover stabilization and re-growth. Whereas in the past forest transition countries have increased the extractive forest rent (e.g., through forest scarcity), in the future protective forest rent, such as through REDD and other markets for public goods, could be the main driver in forest protection.
The paper suggests that, at higher scales, the trade-off between food production and forest conservation is limited: “… Only a small share (<10%) of the agricultural output increase [3.3% per year from 1985-2004] has come from deforestation.”

“At the national level, higher volumes of agricultural trade have delinked domestic and local consumption from production and deforestation. Moreover, high rates of deforestation for several decades have made forested areas recede, frequently into relatively inaccessible areas. The issues of forest conservation and agricultural production are becoming increasingly spatially delinked.”

Agricultural intensification efforts, therefore, should “target low-forest areas, or crops and production systems that are unsuitable at the agricultural frontier.”
Angelsen, A. (2010). Climate Mitigation and Food Production in Tropical Landscapes Special Feature: Policies for reduced deforestation and their impact on agricultural production Proceedings of the National Academy of Sciences, 107 (46), 19639-19644 DOI: 10.1073/pnas.0912014107... Read more »

Angelsen, A. (2010) Climate Mitigation and Food Production in Tropical Landscapes Special Feature: Policies for reduced deforestation and their impact on agricultural production. Proceedings of the National Academy of Sciences, 107(46), 19639-19644. DOI: 10.1073/pnas.0912014107

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