By: Maggilyn Cardenas
Savannas found in West Africa have been converted to croplands and are one of the most vulnerable regions to climate change. The deterioration of soil fertility and the decrease in crop yields seen in this area has been a threat to food security and human livelihoods. The annual population growth in Ghana from 2000 to 2008 was 2.81%, while the annual food increase rate was 1.26%. Therefore, the availability of water and nutrients is thought to be critical. This not only affects West Africa but the whole world, given that Savannas are globally important ecosystems vial to human economies, cover one-fifth of the earth's land surface and support a large proportion of human livestock and wild herbivore mass. Because of climate change, the changes in the distribution and dominance of different species and constraints from soil nutrient availability could change the savanna for the better. Soil nitrogen is thought to have decreased. If this limitation to land productivity resulting from the insufficient supply of nitrogen is spread, it will become a critical constraint on global terrestrial responses to climate warming. Therefore, a modest rate of fertilizer application, around 30 kg N ha-1 year-1, could lead to sustainable and productive cropping systems. The food security and agricultural sustainability in the savanna will have to depend on N fertilization rates.
Reference
Tan, Z., Tieszen, L. L., Liu, Shuguang, L., Tachie-Obeng, E. 2009. Modeling to evaluate the response of savanna-derived
cropland to warming–drying stress
and nitrogen fertilizers. Climatic Change. 100:703-715.

Considering the tragic events of this year on forests, more than ever it should be taken into account the methods that could be practiced on other regions to conserve land and resources for cropping.
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