ShiftingCultivation
as an Agroecosystem:

being a subsistence system, the essential inputs from:

1)the natural environment.
2)the simple agricultural traditions of the shifting cultivators.

economic factors an political influence as secondary inputs.

on the output side, crop yields account for the largest share.

depending on the kindness of nature as the shifting cultivatiors have marely limited skill and resources in cushioning the effects of a harsh physical environment.

however, as an open system, the agroecosystem of shifting cultivation is liable to be affected by external forces.

in the traditional shifting subsistence system, given the present natural environment, skills and resources of the people, there will be no tendency for any change to occur.

external impact, say the introduction of an exotic resource in the form of steel axes, cause adjustment to the system.