Forests and farms: understanding a shifting cultivation system in the Eastern Himalaya

Shifting cultivation, a mountain farming system involves a continuous cycle of forest clearing, cultivation and natural regeneration. Since it involves clear-felling, it is blamed for causing deforestation and for associated ecological damage. However, the practice affects forests at smaller spatial scales than commercial monoculture plantations that result in permanent conversion of large areas. The practice provides food security to remote farming communities and is also intricately interwoven with their culture. Disregarding this, government policies since the British colonial period till today have focussed on introducing settled cultivation and cash crop options, unmindful that local institutions have internally regulated the practice. Further, the shift to settled cultivation options entail economic and cultural costs, which I tried to understand through interviews with the Adi tribe in Arunachal Pradesh. Although settled cultivation was initiated in the sixties, about 90 % of the families practice shifting cultivation, observing 13 festivals associated with the annual agricultural calendar. The economic status of a household affected the ability to undertake settled cultivation, while labour availability was important for shifting cultivation. Often, these nuances are ignored in government policies and future interventions should be mindful of cultural and socio-economic factors that affect the community and not use a one-size-fits-all strategy.

I then focused on the regenerating forests that are integral to shifting cultivation landscapes. To understand forest recovery following cultivation, I sampled the vegetation in sites with 2, 12, 25 and 50 years of natural regeneration following cultivation and the adjoining uncut forest. Species richness recovery was rapid while composition recovery was relatively slow. Sites regenerating following recent cultivation comprised biotically-dispersed and pollinated trees with small propagules while uncut forest and older sites had abiotically-propagated species with taller trees and heavier wood. A trait-based analysis was useful to identify these patterns. To understand forest recovery processes, I undertook experiments to determine the effect of age of site, herbivory exclusion, shade and above-ground vegetation on seedling survival. The shifting cultivation landscape provided a natural experimental setup required to understand the factors important for seedling survival of species with different life histories. Seedlings of a mature forest, a pioneer and a mid-successional species were introduced in different-aged successional sites and an uncut forest site and monitored for up to two years. Herbivory affected the pioneer species significantly and clearing above-ground vegetation reduced the survival of the species, indicating facilitation by existing vegetation. The mature forest species had the highest survival in uncut forest with almost zero survival in the early successional site. These findings have implications for restoration: 1) introducing pioneer and mid-successional species instead of mature forest species may be initially more effective to ensure survival, and, 2) retaining pioneer species in clearings while introducing seedlings in large numbers or providing herbivory exclosures may result in higher survival of pioneer tree species. My doctoral research provided a better understanding of the dependence of a remote farming community on traditional shifting cultivation and new insights into forest recovery patterns and processes following cultivation.

About the speaker

Karthik's research interest lies in plant ecology: in understanding impacts of anthropogenic effects and climate change on vegetation. For his Masters’ and PhD research, he studied forest recovery following clear-felling for cultivation. He completed his Ph.D. from Nature Conservation Foundation (NCF) affiliated to Manipal University. He is also interested in the interactions between forest-dwelling human communities and nature and undertook sociological surveys in a remote site in North-east India. In addition to social and ecological research, he is also keen on working on conservation issues that affect forests and grasslands in India. In his free time, he loves to listen to and play music and also has a keen interest in writing articles about nature.