Soil Carbon stocks

Guo, L. B., and Gifford, R. M. (2002). Soil carbon stocks and land use change A meta analysis. Global Change Biology 8(4), 345-360. 

Moraes, J. L., C.C. Cerri, J. M. Melillo, D. Kicklighter, C. Neill, D.L. Skole, and P. A. Steudler. 1995. Soil carbon stocks of the Brazilian Amazon basin. Soil Science America Journal 59 244-247. 

At present, LCA is able to emphasise the avoidable environmental burdens of materials which are potentially replaceable via composting, while benefits from carbon sequestration and the resulting variations in soil carbon stocks are still an open methodological issue, on which a full scientific consensus has not yet been achieved. 

The obtained results allow us to advance with the basic assumption the north sector, subject to anthropogenic influence, it showed a carbon stock 23% lower than the south sector, which had less accessibility and a better state of conservation (Table 4). These differences were statistically significant (H = 11.20, p < 0.001) only for the AGB stratum, but not for the other strata studied nor for the total carbon stock. Under similar conditions of climate, soil, geomorphology, altitude, and latitude, the human influence could explain these differences, as the AGB stratum is the easiest to appropriate by humans [10,17,19, 21]. The AGB make the largest contribution in both sectors to the carbon stock (53, 55%), followed by SOC (28-31%) and finally BGB (8-10%) depending on the sector analyzed (Figure 3). 

Figure 5. Carbon footprint of different types of food products at retail. Average values estimated to be representative for food products sold on the Swedish market. Error bars show ranges of values found in the literature. Emissions from land use change and carbon stock changes in soils are not included [47]...

Leifeld J, Kogel-Knabner I (2005) Soil organic matter fractions as early indicators for carbon stock changes under different land-use Geoderma 124 143-155... 

Figure 2.1. Diagram of factors controlling the main inputs and outputs of soil carbon, superimposed over a global map of soil organic carbon stocks. DOC, POC, and DIC stand for dissolved organic C, particulate organic C, and dissolved inorganic C, respectively. The background soil organic carbon (SOC) map (Miller Projection 1 100,000,000). See color insert. Reprinted from Davidson, E. A., and Janssens, I. A. (2006). Temperature sensitivity of soil carbon decomposition and feedbacks to climate change. Nature 440,165-173, with permission from Macmillan.

Empirical Estimates of Global Carbon Stocks in Soils 221... 

Fauna also influence soil carbon cycling. Bioturbation mixes and aerates soil, physically breaks down litter, creates flow paths for water in soil, and can reduce surface litter stocks and enhance erosion (Bohlen et al., 2004). For example, along a gradient of European earthworm (Lumbricus terrestris) colonization in a deciduous forest of northern Michigan, earthworms are associated with a decrease in litter-layer thickness, apparently mixing some forest floor organic matter into the mineral soil. Thus, fauna can create spatial patterns in SOM stocks. 

Plant productivity is determined by factors such as plant species composition, moisture, soil fertility, growing season length, and solar radiation—many of which are affected by human activities. All else equal, increases in primary productivity and production of plant tissues will lead to increases in soil C stock, while decreases will lead to decreases in soil C stock. The rate of change in soil C stock is determined by the difference between C inputs and outputs, as well as the turnover times of the soil C, which are often not known. Here we review briefly how some environmental factors are expected to alter productivity and explore how the effects on stock depend on the number of soil carbon pools and their turnover times. 

Davidson, E. A., and Lefebvre, P. A. (1993). Estimating regional carbon stocks and spatially covarying edaphic factors using soil maps at three scales. Biogeochemistry (Dordrecht) 22(2), 107-131. 

Neill, C., B. Fry, J. M. Melillo, P. A, Steudler, J. F. Moraes, and C. C. Cerri. 1996. "Forest and pasture-derived carbon contributions to carbon stocks and microbial respiration of tropical pasture soils." Oecologia 107 113-119. 

Carbon stocks did not exceed 22 kg Cm for the 0-100 cm layer, and for the three major soil types the variation was less, ranging from 8.5 to 10.5 kg Cm 2. These estimates were similar to others for tropical soils based on less extensive regional data (Brown and Lugo 1982, Post et al. 1982), and to global averages for tropical Oxisols, Ultisols, and Alfisols (Kimble et al. 1990, Batjes 1996). 

Moraes et al. (1995) neglerted the volume of the soil fraction superior to 2 mm. Using a soil dataset made up with soil profile descriptions in Rondonia (Occidental Brazilian Amazon) we calculated that considering the > 2 mm fraction would decrease carbon stocks (at Im... 

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