Cerrado biomass

Table 5.2 Live aerial biomass (dry weight) of the different components of the trees (girth > 5cm at 30 cm height) of a cerrado sensu stricto on a dark red latosol (Haplustox) at the Fazenda Agua Limpa in Brasilia.

A comparison of these data with those of an Amazonian forest shows that the aerial biomass of the trees of a cerrado sensu stricto in central Brazil may be only 8 to 22% of that of an Amazonian forest, and the basal area only 10 to 26% (Table 5.3). This difference in biomass reflects directly on the nutrient pools in the biomass. A comparison of the data reported by Klinge et al. (1995) for the aboveground biomass and nutrient stock in two inundation forests in the Ilha de Marchantaria with the data for a cerrado sensu stricto from central Brazil (Silva 1990) illustrates how nutritionally poor the cerrado is in quantitative terms. The proportions of stock of essential nutrients in the tree biomass of cerrado are 7 to 16% for P, 1.7 to 4.6% for K, 0.83 to 3.09% for Ca, and 3.5 to 7.4% for Mg. Thus Ca, K, and Mg seem to be much more deficient in the cerrados than P. We have no corresponding data for the stock of nutrients in the root biomass of trees for comparison among the two ecosystems. This comparison is only illustrative of two specific sites. Estimates of aboveground biomass for the Amazonian forests may vary... 

Mg ha i) in a cerrado sensu stricto. In the campo limpo, which is devoid of trees, the aerial biomass (5 5 Mg ha i) amounted to only 34% of the root biomass (16.3 Mg ha ) in the top 2 m of soil. This proportion was 31% in the campo sujo with its sparse distribution of trees and 47.9 to 53 3 in the cerrado sensu stricto. Thus the different cerrado vegetation types showed a higher root/shoot ratio than many tropical forests. 

Batmanian and Haridasan (1985) estimated the primary production of the herbaceous layer of a cerrado sensu stricto to be 3.27 Mg ha i yr using the peak biomass method, with the grasses contributing 68 to 78% of the live biomass of the herbaceous layer. Thus, the transfer of nutrients from soil or litter to live biomass should be of the order of 20 kg ha-i yx-t of N, 2 kg P, 20 kg K, 10 kg Ca, and 3 kg Mg. Even allowing for the higher estimates of primary production and live biomass of the herbaceous layer from other studies, these amounts are insignificant when... 

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-... 

Castro, E. A. 1995. Biomass, nutrient pools and response to fire in the Brazilian cerrado. Master s thesis. Oregon State University. Corvallis. 

Kauffman, J. B., D. L. Cummings, and D. E. Ward. 1994. Relationships of fire, biomass and nutrient dynamics along a vegetation gradient in the Brazilian cerrado. Journal of Ecology. 82 519-531. 

De Castro, E. A. and Kauffman, J. B. (1998). Ecosystem structure in the Brazilian Cerrado a vegetation gradient of aboveground biomass, root mass and consumption by fire. /. Trap. Ecol. 14, 263-283. 

Recent studies in Sao Paulo state (Toppa, 2004) have demonstrated a strong correlation between cerrado biomass, floristic composition and soil-water capacity (sand/clay proportion), the last of which was shown to be a more important factor than fertility, acidity or aluminium saturation of the soil. This is a revival of the ideas of more than a hundred years ago (Warming, 1892), when water availability was considered to be the main constraint to the occurrence of forest vegetation in the cerrado domain. 

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