Organic matter litter decomposition

The spread and growth of Typha in the impacted zone may be directly linked to the increased supply of bioavailable nutrients liberated through an enhanced decomposition of P-enriched litter and organic matter. 

Figure 14.10. Principal component analysis of Py-FI mass spectra of (a) cold and (b) hot water extracts from the sequence of organic litter layers Oi-Oe-Oa in a beech stand (Fagus sylvat-ica) obtained before (-pre) and after (-post) aerobic incubation. The arrows indicate changes due to progressive decomposition top-down in the litter profile. Reprinted from Landgraf, D., Leinweber, P, and Makeschin, F. (2006). Cold and hot water extractable organic matter as indicators of litter decomposition in forest soils. Journal of Plant Nutrition and Soil Science 169,76-82, with permission of Wiley-VCH.

Landgraf, D., Leinweber, R, and Makeschin, F. (2006). Cold and hot water extractable organic matter as indicators of litter decomposition in forest soils. J. Plant Nutr. Soil Sci. 169, 76-82. 

Figure 3.1 Decomposition and carbon turnover in soil A conceptual diagram summarizing the main elements of the initial Rothamsted carbon model (Jen-kinson 1971). To this we have added other small, but potentially functionally important, compartments the volatile organic carbon and the dissolved organic carbon derived during both decomposition of litter and exudation from plants. An inert organic matter pool is added as this appears in later versions of the Rothamsted model.

Production of roots on top of the mineral soil has been explained as a consequence of the low nutrient availability in Amazon forests (Herrera et al. 1978, Cuevas and Medina 1983, Medina and Cuevas 1989). Vertical root distribution results from differential nutrient availability in the soil profile (Berish 1982, Berish and Ewel 1988). Shallow rooted systems may be a result of litter and soil organic matter production and decomposition rates in systems where nutrient input from litter exceeds that of nutrient release by soil weathering, as is the case of Ca, Mg, and P in terra firme forests (Medina and Cuevas 1989). In the Middle Caqueta region of Colombia, for example, Ca and Mg concentrations in the L and F layers are between 15 and 20 times higher than in the mineral soil (Duivenvoorden and Lips 1995). 

It should be noted that reactions (1) and (2) represent the sum of many intermediate reactions. These include the photosynthetic fixation of CO2 as biomass, the secretion of organic and carbonic acids by roots and associated microflora, the decomposition of litter and soil organic matter to form soil CO2, the reaction of CO2 with water to form carbonic acid, the reaction of organic and carbonic acids with calcium and magnesium silicates, and the formation of dissolved calcium, magnesium, and bicarbonate in soil and groundwater. 

The quantity of litter input provides the second critical link between NPP and decomposition because NPP governs the quantity of organic matter inputs to decomposers. When biomes are compared at steady state, heterotrophic respiration (i.e., the carbon released by processing of dead plant material by decomposer organisms and animals) is approximately equal to NPP. In other words, net ecosystem production (NEP), the rate of net carbon sequestration, is approximately zero at steady state, regardless of climate or ecosystem type. This indicates that the quantity and quality of organic matter inputs to soils, as determined by... 

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