Swidden agriculture in transition and its roles in tropical forest loss and plantations expansion

Abstract

Tropical forest and swidden agriculture are declining, while commercial plantation is continuously expanding. However, little is known about the mechanisms, processes and trends of the tropical forest-swidden-plantation (FSP) nexus. Global ongoing initiatives including the UN-REDD Programme, not only have repeatedly emphasized the significance of conserving forests, reforestation and afforestation, but re-pushed swidden agriculture to the forefront of a long-standing international debate of climate changes and biodiversity. Many facets limit our understanding of swidden agriculture. The lack of geographic and demographic data and their dynamics across the tropics undoubtedly further aggravate this situation since the first appeal of eradication of shifting cultivation by the FAO. Although recent studies have enriched significantly our knowledge of forest loss and plantation expansion, previous research has proceeded separately and has yet to be integrated under the umbrella of sustainable swidden agriculture. Efforts are needed to investigate the dynamics of the FSP nexus for sake of a synergetic goal of climate mitigation and poverty alleviation.

Agricultural expansion and forest retreat in Mainland Southeast Asia since the late 1980s

“…MSEA, as a hotspot of forest conversion and agrarian transformation, has experienced the highest rates of FL among the TAFF in past decades (Estoque et al, 2019;Kim et al, 2015). Also, the increasing number of fire occurrences in MSEA indicates that more vegetation burning events and upland slash-and-burn farming are happening, posing further threats to forests (Li et al, 2021;Xiao et al, 2022;Zeng, Gower, & Wood, 2018). To understand the role and contribution of cropland expansion (CE) and PE to drive FL, over three decades of RLCMS land-cover products were used to retrospectively examine the magnitudes and processes of agricultural advance and forest retreat in MSEA.…”

“…We thus believed that incorporating the accurate portrayal of TAFF's agricultural advance and forest retreat into regional and global climate models should be an immediate priority (Zeng, Estes, et al, 2018). Notably, markets and infrastructure development, population growth and migration, and national or regional policies, as well as geoeconomic cooperation and telecoupling as the potential drivers of agricultural expansion and forest retreat in plantation boom in the TAFF (Li et al, 2021;Rudel, 2009;van Vliet et al, 2012). Our study, however, does not present a full and In view of the research status and importance of the "advance and retreat" of agriculture-forest in their frontiers, it is necessary to strengthen the research on measures to maintain forested areas and their integrity.…”

“…There are differences in deforestation ways and land conversion patterns across continents, such as pasture establishment and crop intensification in the Brazilian Amazon (Garrett et al, 2018), small-scale agricultural expansion in the Congo Basin (Tyukavina et al, 2018), cropland and commercialized plantations expansion in Southeast Asia (Xiao et al, 2021;Zeng, Estes, et al, 2018), and woody encroachment in the forest-savanna transitional area of Africa (Brandt et al, 2018;Mitchard et al, 2011); therefore, previous research has greatly enriched our knowledge of FL and agricultural expansion or intensification (Feng et al, 2021;Margono et al, 2014;Stibig et al, 2014;Zhai et al, 2022). Understanding of the advance and retreat of agricultural forests in the TAFF is, however, still poor because the dynamics (including magnitudes and processes) are complex and regionally diverse, let alone the longitudinal and horizontal mechanisms and drivers (Li et al, 2021;Stibig et al, 2014). Most importantly, detailed spatial information on long-term agricultural expansion and forest retreat in TAFF is still lacking.…”

“…Mainland Southeast Asia (MSEA), as the main part of the Indo-Burma Biodiversity Hotspot, has the third largest tropical forests globally but has experienced the highest deforestation rates since the 1990s (Dong et al, 2012;Estoque et al, 2019;Kim et al, 2015). Earlier studies have shown that swidden agriculture, commercialized plantations, legal or illegal logging, fire, and mining lead to iterant forest conversion (or loss), transition, and regrowth or degradation to varying degrees (Curtis et al, 2018;Li et al, 2021). For example, the extent of traditional swidden agriculture increased from the 1980s to 2000s and decreased in the 2010s, with about 5.23 million hectares in MSEA (P. Li, Feng, Xiao, Boudmyxay, et al, 2018); however, the implementation of eradication or restrictive policies for swidden agriculture within the MSEA's five countries in recent decades delayed the process of agricultural advance and forest retreat (Li et al, 2018;van Vliet et al, 2012;Zeng et al, 2021); moreover, illegal-logging contributes to the retreat of natural forests and then provides space for agricultural expansion or intensification (Baccini et al, 2017;Davis et al, 2015;Wilcove et al, 2013).…”

“…Issues like coarse resolution (e.g., 250 m or 0.25 ) of the stratified sampling and the focus on FL or tree-based crops boom may, however, limit the understanding of the temporal process and detailed heterogeneity of the advances and retreats (Hurni et al, 2017;Hurni & Fox, 2018;Zeng, Estes, et al, 2018). More importantly, the roles of agricultural expansion and intensification in FL are usually overlooked or mixed up (Li et al, 2021;Tropek et al, 2014). For example, orchards and/or certain plantations are classified as forests (Tropek et al, 2014), and FL was considered as completely cleared in the pixel (Zeng, Gower, et al, 2018).…”