Our work has shown that the hydrological and geomorphological impacts of traditional swidden cultivation in Montane Mainland Southeast Asia are virtually inconsequential, whereas the impacts associated with intensified replacement agricultural systems are often much more substantial. Negative perceptions toward swiddening in general by governments in the region beginning half a decade ago have largely been based on cases of forest conversion and land degradation associated with (a) intensified swidden systems, characterized by shortened fallow and extended cropping periods and/or (b) the widespread cultivation of opium for cash after the Second World War. Neither of these practices should be viewed as traditional, subsistence-based swiddening. Other types of intensive agriculture systems are now replacing swiddening throughout the region, including semi-permanent and permanent cash cropping, monoculture plantations, and greenhouse complexes. The negative impacts associated with these systems include changes in streamflow response, increased surface erosion, a higher probability of landslides, and the declination in stream water quality. Unlike the case for traditional swiddening, these impacts result because of several factors: (1) large portions of upland catchments are cultivated simultaneously; (2) accelerated hydraulic and tillage erosion occurs on plots that are cultivated repetitively with limited or no fallowing to allow recovery of key soil properties, including infiltration; (3) concentrated overland flow and erosion sources are often directly connected with the stream network; (4) root strength is reduced on permanently converted hillslopes; (5) surface and ground water extraction is frequently used for irrigation; and (6) and pesticides and herbicides are used. Furthermore, the commercial success of these systems relies on the existence of dense networks of roads, which are linear landscape features renowned for disrupting hydrological and geomorphological systems. A new conservation focus is needed to reduce the impacts of these intensified upland agricultural practices.
Intensified landuse, characterized by shortend fallow periods and extended periods of cultivation, has led to a degraded landscape in this location in northern Laos
Trends, drivers and impacts of changes in swidden cultivation : A global assessment
This meta-analysis of land-cover transformations of the past 10–15 years in tropical forest-agriculture frontiers world-wide shows that swidden agriculture decreases in landscapes with access to local, national and international markets that encourage cattle production and cash cropping, including biofuels. Conservation policies and practices also accelerate changes in swidden by restricting forest clearing and encouraging commercial agriculture. However, swidden remains important in many frontier areas where farmers have unequal or insecure access to investment and market opportunities, or where multifunctionality of land uses has been preserved as a strategy to adapt to current ecological, economic and political circumstances. In some areas swidden remains important simply because intensification is not a viable choice, for example when population densities and/or food market demands are low. The transformation of swidden landscapes into more intensive land uses has generally increased household incomes, but has also led to negative effects on the social and human capital of local communities to varying degrees. From an environmental perspective, the transition from swidden to other land uses often contributes to permanent deforestation, loss of biodiversity, increased weed pressure, declines in soil fertility, and accelerated soil erosion. Our prognosis is that, despite the global trend towards land use intensification, in many areas swidden will remain part of rural landscapes as the safety component of diversified systems,particularly in response to risks and uncertainties associated with more intensive land use systems.
Van Vliet, N, O Mertz, A Heineman, T. Langanke, U. Pascual, B Schmook, C. Adams, D. Schmidt-Vogt, P. Messerli, S Leisz, J-C, Castella, L Lrogensen, T Brich-Thomsen, C Hett, T Bech-Bruun, A Ickowitz, Kim Chi Vu, K. Yasuyuki, JM Fox, C Padoch, W, Dressler, AD Ziegler. 2012 Trends, drivers and impacts of changes in swidden agriculture on tropical forest frontiers: a global assessment. Global Environmental Change 22(2): 418-429
Recognizing Contemporary Roles of Swidden Agriculture in Southeast Asia
In this paper we argue that Swidden agriculture is still the most rational land use for farmers in forests in some instances, from both economic and environmental perspectives (Fox et al. 2009; Padoch & Pinedo-Vasquez 2010). Although conservation policies and market forces will likely continue pushing swidden farmers toward commercial agriculture, we think swiddening should be encouraged in areas where it contributes to the preservation of ecosystem services and cultural identity. Relevant to the current global change debate, we believe REDD+ policies should not preclude maintaining or rehabilitating traditional swidden systems with fallow periods that are sufficiently long to allow regeneration of mature secondary forests.
Ziegler, AD, JM Fox, EL Webb, C Padoch, S Leisz, RA Cramb, O Mertz, TT Bruun, Tran Duc Vien. 2011. Recognizing Contemporary Roles of Swidden Agriculture in Transforming Landscapes of Southeast Asia. Conservation Biology 25: 846-848.
Other publications (go to the Pub Hub)
Fox, FM, JB Vogler, OL Sen, TW Giambelluca, AD Ziegler. 2012. Simulating land-cover change in Montane Mainland Southeast Asia. Environmental Management 49(5): 968-979.
Ziegler, AD, JM Fox, J Xu. 2009. The rubber juggernaut. Science 324: 1024-1025.
Rerkasem, K, D Lawrence, C Padoch, D. Schmidt-Vogt, AD Ziegler. 2009. Consequences of swidden transitions for crop and fallow biodiversity. Human Ecology 37: 347-360.23.
Ziegler, AD, TB Bruun, M Guardiola-Claramonte, TW Giambelluca, D Lawrence, Nguyen Thanh Lam. 2009. Environmental Consequences of the Demise in Swidden Agriculture in SE Asia: Hydrology and Geomorphology. Human Ecology 37: 361-373. 24.
Bruun, TB, A De Neergaard, D Lawrence, AD Ziegler. 2009. Environmental Consequences of the Demise in Swidden Agriculture in SE Asia: Soil Nutrients and carbon stocks. Human Ecology 37: 375-388.
Ziegler AD (PI, NUS/UHM), RC Sidle (Kyoto), S Wood (BSU), XX Lu (NUS), A Snidvongs. 2009-2010. Sediment Dynamics in Tropical Streams Affected by Land-cover/Land-use & Climatic Change. Asia Pacific Network, grant no #ARCP2008-01CMY ($40,000): Thailand, Vietnam, China, India.
Ziegler AD (PI, UHM), RC Sidle (Kyoto), S Wood (BSU), XX Lu (NUS), A Snidvongs. 2007-2008. Sediment Dynamics in Tropical Streams Affected by Land-cover/Land-use & Climatic Change. Asia Pacific Network, grant no #ARCP2007-01CMY ($40,000): Thailand, Vietnam, China, India.
Ziegler AD (PI) (UHM), R.C. Sidle (Kyoto), S. Wood (BSU), X.X. Lu (Singapore), A. Snidvongs (Bangkok). 2006-2007. Sediment Dynamics in Tropical Streams Affected by Land-cover/Land-use & Climatic Change – Thailand Phase. Asia Pacific Network, grant no #ARCP2006-06NMY ($40,000): Thailand.
Fox JM (PI, E-W Center), TW Giambelluca (UHM), B Njissen (U Arizona), S Walsh (UNC), O Sen (Turkey), AD Ziegler (UHM). 2004-2007. Role of land-cover change in montane mainland Southeast Asia in altering regional hydrological processes under a changing climate. NASA (NNG04GH59G) ($900,000): SE Asia.