The uncertainties of the development of swidden agriculture and its dynamics
Many facets limit our understanding of swidden agriculture. The lack of geographic and demographic data and information on their corresponding dynamics across the tropical regions undoubtedly further aggravate the uncertainties surrounding above questions(Heinimann et al., 2017; Mertz & Padoch et al., 2009; Padoch et al., 2007). Ever since the first appeal of the eradication of shifting cultivation by the FAO in the late 1950s(FAO Staff, 1957), in situ anthropological, ethno-ecological and/or ethno-biological studies dominated for a long time(Brush, 1975). The launch of Landsat satellites in the 1970s offers the feasibility and marks the beginning of periodically observing this ancient farming system(Conant & Cary, 1977). However, research progress in the algorithms for mapping swiddening or shifting cultivation is not prominent, if not retarded or stagnant(Li, Feng, Jiang, Liao, & Zhang, 2014). So far, the only thematic map of global shifting cultivation, largely speculative and conspicuously old-fashioned, was firstly reported in 1980(Hurtt et al., 2011), although a few new attempts have emerged recently at regional scale, e.g. montane mainland Southeast Asia(Li, Feng, Xiao, Boudmyxay, & Liu, 2018; Li & Feng, 2016). In addition, the annually-changing and spatially-random dynamics of swidden agriculture mean that it is seldom included in existing classification maps of land cover and land use(Padoch et al., 2007), plus prevailing governmental eradication policies. The report of shifting cultivation maps in South and South East Asia, China, Africa, and South America based on the SPOT-VGT based Global Land Cover 2000 (1km) can be consider an early attempt via remote sensing at large scale(Silva, Carreiras, Rosa, & Pereira, 2011). However, the question about the accuracy of the 1km-resolution regional maps always persists as tropical swidden agriculture belongs to small-scale farming systems with small-sized plots (about 0.01km2)(Li et al., 2014). Even worse, longitudinal dynamics of the evolution or transformation at a coarse resolution increases greater uncertainty. Unsurprisingly, few studies have been involved the spatiotemporal dynamics(Li et al., 2018). Lately, the contributions of shifting agriculture and other four factors to global deforestation were quantitatively for the first time(Curtis, Slay, Harris, Tyukavina, & Hansen, 2018). However, the fact that shifting cultivation is still practiced in many extra-tropics regions including Europe, North America, Australia, North China and many other countries is problematic and unconvincing. Since shifting cultivation is one of the main causes of tropical active fires(Cochrane, 2003; Li, Xiao, Feng, Li, & Zhang, 2020) and shifting cultivators are typically poor ethnic minorities in remote uplands with limited accessibility(Mertz & Leisz et al., 2009), the estimation of greenhouse gas emissions and achievement of the SDGs will be impacted without accurate figures and maps for the land coverage of swidden agriculture.
Shifting agriculture as well as commodity production, forestry and wildfire are the leading drivers of global forest loss(Curtis et al., 2018). Among them, the first two were preeminent in tropical regions particularly in the past two decades, which are always accompanied by frequent fire occurrence or biomass burning especially during the dry season. Anthropogenic fires not only occur in tropical upland and lowland agriculture, but also in tropical agriculture-forest frontiers (TAFF)(Li et al., 2020). In the uplands, vegetation fires are generally related to traditional practice of slash and burn(Cochrane, 2003), which acts as a key part of swidden agriculture. In the past, the words of “slash and burn” meant primitive and backward, or the stumbling block of national economic development. By the same token, the overgeneralization of describing swidden system as old as the hills could make us bet on the wrong horse(Pham Thu, Moeliono, Wong, Brockhaus, & Dung, 2020). Conversely, this becomes more necessary as increasing evidence are connected with social and ecological outcomes of this farming system(Downey, Gerkey, & Scaggs, 2020; Ziegler et al., 2012). The positive effects of swidden agriculture are gaining ample and convincing evidence in the aspects of carbon fixation, biodiversity maintenance, livelihoods risk and cultural identity(Dressler et al., 2020). Then, why should we still stick to the one-sided views of swidden systems?