Environmental Consequences of the Demise in Swidden Cultivation in Southeast Asia: Carbon Storage and Soil Quality

Abstract

The effects of swidden cultivation on carbon storage and soil quality are outlined and compared to the effects of the intensified production systems that swidden systems of Southeast Asia transform into. Time-averaged aboveground carbon stocks decline by about 90% if the long fallow periods of traditional swidden cultivation are reduced to 4 years and by about 60% if swidden cultivation is converted to oil palm plantations. Stocks of soil organic carbon (SOC) in tree plantations are 0-40% lower than stocks in swidden cultivation, with the largest losses found in mechanically established oil palm plantations. Impacts of tree plantations on soil quality are to a large extent determined by management. Conversion of swiddening to continuous annual cropping systems brings about substantial losses of time-averaged aboveground carbon stocks, reductions of SOC stocks and generally leads to declining soil quality. Knowledge of carbon storage in belowground biomass of tree based systems of the tropics is sparse but failure to include this pool in carbon inventories may significantly underestimate the total biomass of the systems. Moreover, studies that consider the ecological reasons behind farmers' land use decisions as well as spatial variability in biogeophysical and edaphological parameters are needed to evaluate the effects of the ongoing land use transitions in Southeast Asia.

Carbon Sequestration Potential and Edaphic Properties Along the Plantation Age of Rubber in Tripura, Northeastern India

“…The carbon content in soil did not vary significantly (ANOVA, F 3, 16 = 1.87; p = 0.18). This result is contrary to the other findings as a decrease in carbon is resulted from an intensified rubber plantation in Southeast Asia 41 . According to Chadwick (1998) 42 , the major source of organic residues in plantations comes from the decomposition of leaf litter that has accumulated on the surface of the soil.…”

Consequences of Swidden Transitions for Crop and Fallow Biodiversity in Southeast Asia

“…Swidden fallows play a crucial role in maintaining the sustainability of swidden systems in various ways: by restoring fertility of the soil-vegetation system and facilitating weed control (Nye and Greenland 1960), by providing a wealth of plant and wildlife products for subsistence and sale (Anderson 1993), and by providing ecosystem services such as regulating water flow, protection against erosion (Ziegler et al 2009b), maintaining long-term carbon stocks (Bruun et al 2009), and habitat for wild plants and animals on a larger landscape scale. Depending on management practices, especially the length of the fallow period, fallow vegetation develops through a sequence of successional stages, the early stages being characteristically dominated by herbaceous plants, the later stages being increasingly dominated by woody growth ranging from secondary scrub to secondary forest (SchmidtVogt 2001).…”

Simulating Stakeholder-Based Land-Use Change Scenarios and Their Implication on Above-Ground Carbon and Environmental Management in Northern Thailand

“…In the case of this study, soil carbon stocks were not considered because especially in tropical environments, maximum carbon sequestration can be often achieved by focusing more on aboveground carbon than on soil organic carbon due to smaller pool sizes and short mean residence times [7,8]:…”