"...I have proposed that, through a chronology of changes from the 1980s to the present day, declining yields per unit of land and labour are among the basic features of contemporary Batak swidden practices. This trend has reinforced public misconceptions about those practices. Furthermore, I have attempted to show that Batak farming knowledge is complex and articulated, contradicting the general view that their agricultural practices are unsophisticated and technologically backward. On the contrary, farming innovations and experimentation continue to take place, often as a way of countering changes confronting the Batak. Clearly, a complex set of events and circumstances, rather than Batak farming ?ignorance?, has contributed to detrimental changes in Batak farming practices, such that the environmental sustainability of these practices can no longer be taken for granted. These events include demographic pressure, loss of important ecological food zones, a drop in seasonal movements, competition over resources, indebtedness and government restrictions on forest use. Undoubtedly, top-down technical approaches to stabilizing shifting cultivation, imposition of imported participatory logic and various forms of external interference have played a major role in the breakdown of Batak social-support systems and mobility patterns..."