Soil-litter system

Forest systems also act as sources of CO2 when controlled or uncontrolled burning and decay of litter occur. In addition, release of ethylene occurs during the flowering of various species. One additional form of emission to the atmosphere is the release of pollen grains. Pollen is essential to the reproductive cycle of most forest systems but becomes a human health hazard for individuals susceptible to hay fever. The contribution of sulfur from forests in the form of dimethyl sulfide is considered to be about 10-25% of the total amount released by soils and vegetation (12). 

Input rates of organic C into the soil system are hard to quantify, particularly for natural ecosystems and to a lesser extent for agricultural ecosystems. Whereas quantity and quality of carbon inputs via litter fall and plant residues after harvest might be directly measurable, inputs via roots and rhizodeposition are more difficult to assess. 

The use of farrowing crates is prohibited for organic producers, and so are routine teeth cutting and the automatic use of iron injections. However, a protective rail, farrowing box or nest is recommended, and teeth cutting for individual piglets or a litter when necessary to prevent injury to the sow is permitted, and so are iron injections for anaemia in the case of iron-deficient soils or chronic anaemia in free range systems. 

Several recent studies investigated the bioavailability of DOM and total hydrolyzable neutral sugars and amino acids in lake (Weiss and Simon, 1999), creek (Volk et al., 1997 Gremm and Kaplan, 1998), and marine (Amon et al., 2001) waters. The DOM in the lake and marine environments was predominantly derived from plankton, whereas the DOM in the creek was predominantly derived from soils and decaying plant litter. Although limited in number, these systems represent a diverse array of aquatic environments. Each of these studies determined the percentages of DOC that were... 

Isotopic Tools Tracers. Carbon has three stable or long-lived isotopes 98.9% of earth s C is 12C, -1.1% is 13C (a stable isotope), and about one in a trillion (1 in 1012) carbon atoms is 14C. By enriching or depleting the ratios of the rare isotopes in plants, plant litter, or other organic material put in soil, it is possible to follow the pulse of altered isotopic ratios (and the carbon compounds they were associated with) as they move through the system. 

The terrestrial environment has been much studied as a decomposition environment for materials of little forensic value, such as leaf litter or dead roots. These provide the basic methods and framework for studying and understanding decomposition of materials in soils. It is only in recent years that this has been applied to forensic taphonomy, in which studies have been conducted with mammalian tissues and cadavers. The burial environment is a complex and dynamic system of interdependent chemical, physical, and biological processes. These processes influence, and are influenced by, the inclusion of a body and its subsequent decay. Though this book deals with what is known in this context, much still remains to be discovered, understood, and applied to forensic science. 

Biomass development (Jordan 1985) and regeneration capacity (Uhl 1987) are not always clearly associated with differences in soil fertility, but they are certainly related to rates and patterns of nutrient cycling (Vitousek and Sanford 1986, Medina and Cuevas 1989, Tiessen et al. 1994b). On poor soils, nutrients may cycle without substantial losses from the system (Baillie 1989, Burnham 1989). In such dystrophic systems, organic matter and particularly the forest litter mat may play an essential role in conserving nutrients for sustaining forest produaion (Stark and Jordan 1978). 

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). 

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