Tanika Scherbinski edited Agro Forestry.tex  almost 10 years ago

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The main advantages of agroforestry over other measures is primarily found in its positive influence on farmers’ income security and through the provision of additional resources and its facilitating role in the growth of crops. Those both aspects add important security in a changing climate setting. Furthermore, agroforestry can even to some extent help mitigating climate change, thus allowing farmers to benefit in multiple ways with respect to food security \citep{Mbow_2014a}. A selection of feedback mechanisms under the application of agroforestry can be found in Figure \ref{feedback} and will be further discussed.   By planting trees and shrubs, farmers can directly benefit through the harvest of additional yield such as fruits or firewood. These contribute to the farmers’ own food supply and possibly provide added income if they are able sell these fruits and firewood on local markets. Following the agroforestry typology, this is an example for a multiple cropping systems with the provision of at least two outputs. The cultivation of trees along with their use as firewood provides further benefits such as a decrease in time that is needed to search for firewood and the prevention of deforestation by reforestation \citep{Mbow_2014a}. However, the availability of additional cheap firewood can have a negative feedback in that it contributes to emission of greenhouse gasses and contributes to domestic air pollution since stoves in homes are often low efficiency \citep{Kiplagat_2011}.   It is particularly the indirect effects of agroforestry that is are  likely to help farmers adapt to a changing climate. For instance, nitrogen-fixing trees bind nitrogen in the ground, and thereby fertilizing it. Since nitrogen is often a limiting factor for plant growth, this extra nitrogen in the ground will help crops to grow without the need for synthetic fertilizers \citep{Fleischer_2013}. Studies have already showed that using fertilizer tree species contributes to a larger maize yield than without the use of any fertilizer \citep{Lasco_2014}. Thus, agroforestry can be seen as a natural adaptation method to ensure soil conservation. Natural soil conservation by trees is also created through year-round surface cover. This stems from the fact that unlike most crops, trees will be on the land for multiple years. In comparison to conventional cultivation with large extents of surface litter and crop residue removal, resulting in soil erosion and increases in probability for water runoff, agroforestry ensures surface covering through trees and thus mitigating these effects \citep{Mbow_2014a}.   A second benefit provided by trees is the provision of shade for the surface below them that allows them to buffer against temperature extremes and therefore decreases evaporation \citep{Mbow_2014a}. This can contribute to a longer growing period for the crops, making them less likely to fail. Furthermore, shade will create a more comfortable working environment for the farmers with potentially positive socio-economic and health effects.