科研之友
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摘要
An experimental slash-and-burn (SABC) site and a site included in the cycle of SABC in 19th century were used as a reference to describe a signature of this cultivation method in sandy soils. Documented slash-and-burn layers were compared to pyrogenic layers from other sites and time periods in attempt to differentiate between results of slash-and-burn cultivation and wild fires. The swidden layers in sandy soils appeared as 5 to 10-cm thick, dark-coloured "humus" layers with a characteristic scalloped lower boundary, formed by numerous constructions of fossorial insects, predominantly sweat bees. The dark coloration originates from high concentrations of charcoal fragments with a median length of 4 to 5 mm, pebbly shape and silt coating, uniformly distributed within the swidden layers. A low proportion of bark and presence of foliage (buds and needles) in charcoal assemblages are characteristic for SABC layers. The phytolith content of SABC layers varied from tens to hundreds of thousands per gram of soil, with up to 50% of phytoliths being charred. The SABC layers contained dendritic and/or panicoid phytoliths and cereal glumes and paleas indicative of in situ cultivation of crops. The palynological signature of swiddens is a pollen spectrum of forest ecosystem with a proportion of fire-dependant taxa, such as Onagraceae pollen and Marshantia spores.
- 出版日期2019-5-20
