Mapping of shifting cultivation reveals gross overestimation of forest cover and underestimation of agriculture cover in Northeast India

Background

Studying shifting cultivation landscapes is fundamentally impeded by the difficulty in mapping and distinguishing shifting cultivation, settled farms and forests. There are foundational challenges in defining shifting cultivation and its constituent land-covers, distinguishing them from other land-uses during satellite image analysis, conceptualizing a suitable mapping framework and identifying consequent methodological specifications. Questions have already been raised about the veracity of official statistics of existing land-uses in the Northeast Indian region. Forest estimates are in doubt too. The objective in the paper is therefore two-fold: 1) to present a rigorous methodological framework and mapping protocol combined with extensive fieldwork and use them to undertake a two-season satellite image analysis to map the forest-agriculture frontier of West Garo Hills district, Meghalaya, Northeast India, and 2)to examine if results of the mapping correspond with official estimates of shifting cultivation and forests.

Findings

Empirically, shifting cultivation is the most extensive land-use in West Garo Hills district, followed by tree plantations and old-growth forest confined to only a few locations (mapping accuracy of ~80%). The extent of commercial tree-plantation crops is positively correlated with shortened fallow periods (high intensity of land-use), i.e., plantation expansion on hills occurs at the cost of land allocated for shifting cultivation leading to intensification (and possibly lowered production). The findings of the paper are in sharp contrast to other estimates, including from the official Forest Survey of India (FSI), The Wastelands Atlas of India and state government statistics, all of which showcase the West Garo Hills landscape as primarily forested (79% forest cover according to FSI) with only small fractions under shifting cultivation. The authors demonstrate that this is a consequence of the lack of clear definitions and poor understanding of what constitutes shifting cultivation and forest.

Implications

The main implications of the results are three-fold: 1) Conceptually, ecologists/physical geographers/social scientists/policy-experts involved in land-use mapping need to be attentive to the socially constructed nature of land categories. There is the need to choose socially relevant categories during mapping and not those ones for which there is an implicit preference or others that are easily separable using image analysis. 2) Methodologically, lack of field-level understanding of shifting cultivation, its farm management and agricultural dynamics, as well as other agriculture and forest hamper clarity in definitions of land-uses such as shifting cultivation/forest/plantations etc., their mapping and accuracy of estimates of these land-uses that are relevant for both environmental decision making and ensuring people's livelihoods. 3) From a policy perspective, the paper calls for an attentive revision of India’s official land-use mapping protocols and have wider significance for remote sensing-based mapping in other shifting cultivation landscapes.


Details of original research article:

Kurien A J, Lele S, Nagendra H. Farms or Forests? Understanding and Mapping Shifting Cultivation Using the Case Study of West Garo Hills, India. LAND. 2019;8:133 https://www.mdpi.com/2073-445X/8/9/133.

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