Biomass Savanna

Tropical forests and savannas are the primary source of C emissions that originate from biomass burning (73, 75). However, temperate forests are also sources of atmospheric carbon. Harmon et al. (77) reported that conversion of primary temperate forests to younger, second-growth forests lead to increases in atmospheric CO2 levels, due to losses in long-term carbon storage within these forests. They ascertained that timber exploitation of 5 million hectares of primaiy forests in the Pacific Northwest of North America during the past century has resulted in the addition of 1,500 Tg of C to the atmosphere. 

Andreae MO, Adas E, Cachier H, Gofer WR III, Harris GW, Helas G, Kopp-mann R, Lacaux JR Ward DE, Trace gas and aerosol emissions from savanna fires, in Levine JS (ed.). Biomass Burning and Global Change, Vol. 1, MIT Press, Gambridge, MA, pp. 278-295, 1996. 

Figure 6.1. Ecosystem area and soil carbon content to 3-m depth. Lower Panel Global areal extent of major ecosystems, transformed by land use in yellow, untransformed in purple. Data from Hassan et al. (2005) except for Mediterranean-climate ecosystems transformation impact is from Myers et al. (2000) and ocean surface area is from Hassan et al. (2005). Upper Panel Total C stores in plant biomass, soil, yedoma/permafrost. D, deserts G S(tr), tropical grasslands and savannas G(te), temperate grasslands ME, Mediterranean ecosystems F(tr), tropical forests F(te), temperate forests F(b), boreal forests T, tundra FW, freshwater lakes and wetlands C, croplands O, oceans. Data are from Sabine et al. (2004), except C content of yedoma permafrost and permafrost (hght blue columns, left and right, respectively Zimov et al., 2006), and ocean organic C content (dissolved plus particulate organic Denman et al., 2007). This figure considers soil C to 3-m depth (Jobbagy and Jackson, 2000). Approximate carbon content of the atmosphere is indicated by the dotted lines for last glacial maximum (LGM), pre-industrial (P-IND) and current (about 2000). Reprinted from Fischlin et al. (2007) in IPCC (2007). See color insert.

Echalar, F., A. Gaudichet, H. Cachier, and P. Artaxo. 1995. Aerosol emissions by tropical forest and savanna biomass burning characteristic trace elements and fluxes. Geophysical Research Letters 22 3039-3042. 

Kauffman et al. (1994) estimated the fuel loads along a vegetation gradient from campo limpo to cerrado sensu stricto near Brasilia. In the cerrado only 27% of the fuel load of 10 Mg ha" was comprised of graminoids the remainder was deadwood and leaf litter. They estimated the nutrient pools in combustible components in the cerrado sensu stricto to be 54.7 kg ha" N, 13.8 kg ha K, 3-5 kg ha P, and 30.5 kg ha" Ca. They concluded that the total biomass of the herbaceous layer of the cerrados was similar to that of other savanna ecosystems. The authors concluded that any loss of N due to fire was negligible compared to the N pool in the soil. Biological N fixation and precipitation inputs would compensate for such losses. Similarly, precipitation inputs would compensate for the loss of P, K and Ca (Schiavini 1983, Coutinho 1979, Pivello-... 

Pg C. Savanna has a total average biomass of 28.4 t/ha and represents 86.3% of the area occupied by nonforest vegetation, with a carbon stock of 0.9 Pg. 

An increment is assumed in aboveground biomass of 3 t/ha of grass for open savanna (Kauffman et al. 1994). 

Sp and Sg were estimated, respectively, from values of aboveground biomass of "campo sujo and "campo limpo" found by Kauffman et al. (1994), for a region of closed savanna near Brasilia. Value for Sp was extrapolated for Tp type. Biomass of roots was estimated assuming the value of 1.6 for the root/stem ratio adopted by Schroeder and Winjum (1995) for vegetation in the savanna/grassland class. 

Liu X. D., Van Espen P., Adams F., Cafmeyer J., and Maenhaut W. (2000) Biomass burning in southern Africa individual particle characterization of atmospheric aerosols and savanna fire samples. J. Atmos. Chem. 36, 135-155. 

The locations of biomass burning are varied and include tropical savannas (Figure 1), tropical, temperate and boreal forests (Figure 2) and... 

Figure 1 A savanna fire with its characteristic long fire front as it traverses across the savanna in South Africa. The low-intensity fire consumes grass and shruhs and consumes on an annual and global basis more total biomass than any other kind of fire (see Table 3) (photograph by J. S. Levine, NASA).

Singh, J. S., Raghubanshi, A, S Singh, R, S and Srivastava, S. C. (1989). Microbial biomass acts as a source of plant nutrients in dry tropical forest and savanna. Nature 338, 499-500. 

McCulley, R. (1998). Soil respiration and microbial biomass in a savanna parkland landscape spatio-temporal variation and environmental controls. M.S. thesis, Texas A M University, College Station, Texas. 

Cijsman, A.J., Oberson, A., Friesen, D.K., Sanz, j.l. and Thomas, R.J. (1997) Nutrient cycling through microbial biomass under rice-pasture rotations replacing native savanna. Soil Biology and Biochemistry 29, 1 433-1 441. 

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