The effect of land-use change
Land use has transformed a large proportion of the land surface, not only converting natural landscapes for human use, but also changing management practices on human-dominated lands. Human actions are responsible for changing the world’s landscapes in clearing tropical forests, practicing subsistence agriculture, intensifying farmland production, and expanding urban centers. (1) Probably the biggest problem following land-use change is greenhouse gas (GHG) emissions, which will change the global climate.
Global anthropogenic GHG emissions have grown since pre-industrial times, with an increase of 70% between 1970 and 2004. Agriculture is the second primary source of emission GHG, after energy production,. (Figure.1) The production of crops and animal products today releases roughly 13% of global greenhouse gas emissions, or about 6.5 gigatons (Gt) of carbon dioxide equivalent (CO2e) per year, without counting land-use change. Even assuming some increases in the carbon efficiency of agriculture, emissions could plausibly grow to 9.5 Gt of CO2e by 2050. When combined with continuing emissions from land-use change, global agriculture related emissions could reach 15 Gt by 2050. (2) To reach this target: sustainable crop production, agriculture must greatly reduce its greenhouse gas emissions — even while boosting production.
Additionally, land-use is of critical importance for biodiversity. (3) Deforestation or modification of natural habitat can have devastating consequences for dependant biodiversity (4).
Food VS Biofuels
Today, environmental impacts associated with the use of fossil fuels, rising fuel prices, as well as potential limitations in supply and concerns about regional and national security are driving the development and use of biomass for bioenergy, biofuels and bioproducts. (5) Incentives exist, including energy and agricultural policies, in several countries to promote further progress in the use of biofuels (e.g. US, EU, Brazil, China and India). (6) One should note that biofuel additives to gasoline were pursued as a means to reduce air pollution. Some food crops like maize (corn), sugarcane or vegetable oil can be used either as food, or to make biofuels. For example, since 2006, a portion of land that was formerly used to grow other crops in the United States now is used to grow corn for biofuels, and a larger share of corn is destined to bio-ethanol production, reaching 25% in 2007. (7)
The expansion of ethanol fuel demand has pushed up prices for primary agricultural products, and as a consequence has made arable land more valuable in the state of Parana in Brazil, displacing areas planted with other now less profitable crops. These findings can be seen in Figure 2, which show the increase in areas planted with sugarcane between 1995 and 2005 and the rise in the value of land in the same period. This represents a shift in land use away from food production and poses a global dilemma, namely the need to feed humanity versus the greater monetary returns to farmers through the incorporation of lands for agro-energy.
Sustainable food production is needed to solve issues around food security, ecosystem health and the rising GHG emissions. More than 800 million people today remain “food insecure,” which means they are periodically hungry. Between 1962 and 2006, the ongoing expansion of cropland was the primary source of ecosystem degradation and biodiversity loss. (8)
There are some options for alleviating the troubles we meet by cultivating food and other crops. When it comes to biofuel crops, we should consider the environmental and social criteria as well as sustainability criteria. Energy balance and soil health are the top two of sustainability criteria. Planting and harvesting existing cropland more frequently, either by reducing fallow or by increasing double cropping, could in theory boost production without requiring new land. Carbon sequestration strategies, which increase soil carbon, can be an important part of a strategy to boost long-term crop production in some areas, and boosting productivity will often in turn help to increase soil carbon.
The land use change is ongoing
Although modern agriculture has successfully improved food production, it has caused extensive environmental damage. For example, increasing chemical fertilizer use for crops has led to the degradation of water quality in many regions. (10) In addition, almost 40% global croplands may suffer some degree reducing soil fertility. In addition, food crops are under pressure from biofuel crops that compete for arable land (11). Thus, more scientific research is needed on second and third generation biofuel feedstocks (advanced biofuels feedstocks) to avoid competition with food production. In short, modern agricultural land-use practices may be trading short-term increases in food production for long-term losses in ecosystem services.
1. Sala, O.E., Chapin, F.S., Armesto, J.J., et al. (2000). Biodiversity – global biodiversity scenarios for the year 2100. Science 287, 1770–1774.
2. World Resources Report: 2013-2014. Editorial: World Resources Institute. ISBN: 978-1-56973-817-7.
3. Bierregaard, R.; Claude G., T. E. Lovejoy, and R. Mesquita (eds.) (2001). Lessons from Amazonia: The Ecology and Conservation of a Fragmented Forest.
4. J. Schmidt, V. Gass, E. Schmid. (2011). Land use changes, greenhouse gas emissions and fossil fuel substitution of biofuels compared to bioelectricity production for electric cars in Austria. Biomass and Bioenergy 35: 4060-4074.
5. Junginger M, Bolkesjø T, Bradley D, et al. (2008). Developments in international bioenergy trade. Biomass and Bioenerg; 32(8):7 17–29.
6. P.Havlık, U. A. Schneider, E. Schmid, et al. (2011). Global land-use implications of first and second generation biofuel targets. Energy Policy 39: 5690–5702.
7. N. Shauk and A. Kumar (2014). Energy crops for biofuel and food security. Journal of Pharmaceutical and Science Innovation, 3(6): 507-515.
8. R. Rathmann, A. Szklo, R. Schaeffer (2010). Land use competition for production of food and liquid biofuels: An analysis of the arguments in the current debate. Renewable Energy 35: 14–22.
9. Watanabe M, Gomes J, Dewes H (2007). Sugarcane-induced changes in the land use in the Parana State, Brazil. In: VI international Pensa conference. Ribeirao Preto: USP.
10. S. Savci (2012). An Agricultural Pollutant: Chemical Fertilizer. International Journal of Environmental Science and Development, 3: 77-80.
11. C. L. Lauber, M. S. Strickland, M. A. Bradford, N. Fierer (2008). The influence of soil properties on the structure of bacterial and fungal communities across land-use types. Soil Biology & Biochemistry 40: 2407–2415.
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