Slash burning

Figure 2. The carbon dynamics of a primary forest prior to and following deforestation and slash burning. Arrows represent the relative magnitude of C flux. In the primary forest (represented by the large box at the top of the figure), the C pool is in a dynamic equilibrium with inputs approximately equalling exports. With deforestation and fire, the balance is altered with exports far exceeding imports.

Figure 7. Another temperate coniferous forest site of the Pacific Northwest, USA following clearcutting and slash burning. Severe levels of deforestation result in large quantities of nutrient losses through wood export, biomass burning and accelerated erosion and leaching losses. (Photograph is by courtesy of Dian L. Cummings. ...

Note that the chemical dimensions do not yield such robust "markers", or tracers, as the isotopic dimensions. For a given combustion source, for example, one is apt to find chemical--but not isotopic—fractionation varying significantly with time, particle size, particle history (differential volatilization or reaction), etc. The ratio K/Fe, for example, was quite different in the fine and coarse fractions from a slash burn (1.5 vs. 0.3) [33] and Pb/Br, which has been popular as an automobile exhaust tracer, varies with the "age" of urban particles [22]. 

Thus, consistent results are obtained about one-fourth of the fine particle mass, or 80 percent of the carbon is accounted for by vegetative-(slash) burn carbon. (The corresponding mass density of fine particles in downtown Portland from slash burning is 21 pg/m3 [33].) The only other major source of carbon is seen to be auto exhaust. 

Isotopic and chemical patterns are given for an ambient sample (downtown Portland) and four sources of carbonaceous particles. The source C contributions (Ct) are expressed as percent of total aerosol mass, and the subscripts refer to Vegetation (slash burning), Road dust, Oil (residual and distillate), and Auto exhaust. Units for the ordinate are also percent of total aerosol mass, except for, 4C which is expressed as dpm/g-aerosol. Abscissa points for each pattern are ordered as l4C, C, Si, Ni, and Pb. 

Core, J. E., Terraglio, F. P., Field and Slash Burning Particulate Characterization The Search for Unique Natural... 

Vicinity slash burn site, Oregon (g/ha) 0-2 cm depth Preburn ... 

Sullivan, T.J. and M.C. Mix. 1985. Persistence and fate of polynuclear aromatic hydrocarbons deposited on slash burn sites in the Cascade Mountains and coast range of Oregon. Arch. Environ. Contam. Toxicol. 14 187-192. 

Lyons, C.E. Tombach, I. Eldred, R.A. Terraglio, F.P. Core, J.E. "Relating Particulate Matter Sources and Impacts in the Willamette Valley During Field and Slash Burning" presented at 72nd Annual Air Pollution Control Association Meeting,... 

Sandberg, D. V., S. G. Pickford, and E. F. Darley (1975). Emissions from slash burning and the influence of flame retardant chemicals. J. Air Pollut. Control Assoc. 25, 278-281. 

Romanya, j., Khanna, P.K. and Raison, R.J. (1994) Effects of slash burning on soil phosphorus fractions and sorption and desorption of phosphorus. Forest Ecology and Management 65, 89-1 03. 

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