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.dwlc.lk |
