Chena and the Elephants

Chena or slash-and-burn agriculture is generally considered a practice detrimental to the environment and a cause of habitat degradation. However, our studies in Sri Lanka have demonstrated that traditional chena agriculture actually creates optimal habitat for elephants. Slash-and-burn is a system of agriculture that is widespread around the world and usually is 'shifting' in nature.

What happens is that a farmer will cut and clear an area of forest, and set fire to it just before the onset of rains. Then with the rains, the ground is cultivated with crops of cereals and vegetables. The harvest is completed soon after the rainy season.

The rest of the year through the dry season, the land is left fallow. Again at the beginning of the wet season, it is cleared of the vegetation that has sprung up and cultivated. After about five years of this cultivation, the land becomes unproductive and a new patch is cleared. This is the reason why chena cultivation is 'shifting' in nature.

During the period that the chenas are cultivated, the left over vegetation from the harvest provides a good source of food for elephants who flock in great numbers to consume it, as soon as the people leave. Then through the dry season, hardy natural plants keep growing in the chena fields, providing fodder for elephants. Therefore, even during the period chenas are cultivated, such areas provide dry season food for elephantsOnce the chenas are abandoned due to decreased productivity, natural plants take over. Although the nutrients in the soil are insufficient to provide a good harvest for farmers, they are still more than sufficient for the natural 'pioneer' vegetation, which springs up with a vengeance. In just a couple of years such fields have vegetation a couple of meters tall and growing profusely. Elephants love this as it provides them with a concentrated source of food.

With time through a process known as 'succession' different species of plants take over and the chena fields become secondary forests. Consequently traditional chenas create ideal habitat for elephants.

Due to the rapidly increasing human population, changes in the aspirations and outlook of people, and pressure from groups that consider chena as a undesirable practice, there is a strong movement to convert chena to permanent cultivation.

However, most chena lands are unarable and can only be cultivated with rain water. Therefore, only one season of crops per year is possible, and such areas cannot support families throughout the year. In addition, the practice of chena has developed over thousands of years as a form of 'shifting' cultivation because of the low nutrient value of the soil. Converting chena lands to permanent cultivation requires the adoption of practices such as mechanical tilling of soil and use of fertilizer. Consequently, the farmer has to bear a high cost of cultivation and needs to cultivate even larger areas to recoup his investment. Because the agriculture still is rain dependant, failure of rainfall results in financial ruin of farmers.

Such permanent agriculture also prevents the growth of natural vegetation in the fields, slowly converting them to bare land, and eliminates their use by elephants and other wildlife.

Therefore, conversion of traditional chena lands to permanent agriculture fields is of doubtful benefit to the people and is detrimental to elephants.

Literature
Fernando P, Wickramanayake E, Weerakoon D, Jayasinghe LKA, Gunawardene M & Janaka HK (2005) Perceptions and patterns in human-elephant conflict in old and new settlements in Sri Lanka: insights for mitigation and management. Biodiversity and Conservation 14:2465-2481.

Collaborators
Department of Wildlife Conservation, Sri Lanka
www.dwc.gov.lk