Türk, la pulsación y el legato: la búsqueda de una base lógica

Es una traducción de: Türk, touch and slurring: finding a rationale, en Early Musie, Vol. XVII núm. 1 (Febrero 1989, pp. 55-59).Luis Carlos Gago (traductor)

No depth-dependence of fine root litter decomposition in temperate beech forest soils

Aims Subsoil organic carbon (OC) tends to be older and is presumed to be more stable than topsoil OC, but the reasons for this are not yet resolved. One hypothesis is that decomposition rates decrease with increasing soil depth. We tested whether decomposition rates of beech fine root litter varied with depth for a range of soils using a litterbag experiment in German beech forest plots. Methods In three study regions (Schorfheide-Chorin, Hainich-Dün and Schwäbische-Alb), we buried 432 litterbags containing 0.5 g of standardized beech root material (fine roots with a similar chemical composition collected from 2 year old Fagus sylvatica L. saplings, root diameter<2mm) at three different soil depths (5, 20 and 35 cm). The decomposition rates as well as the changes in the carbon (C) and nitrogen (N) concentrations of the decomposing fine root litter were determined at a 6 months interval during a 2 years field experiment. Results The amount of root litter remaining after 2 years of field incubation differed between the study regions (76 ± 2 % in Schorfheide-Chorin, 85 ± 2 % in Schwäbische-Alb, and 88±2 % in Hainich-Dün) but did not vary with soil depth. Conclusions Our results indicate that the initial fine root decomposition rates are more influenced by regional scale differences in environmental conditions including climate and soil parent material, than by changes in microbial activities with soil depth. Moreover, they suggest that a similar potential to decompose new resources in the form of root litter exists in both surface and deep soils

A versatile method for the reliable determination of polysaccharides (inulin, polyfructans, starch) as non-structural carbohydrates (NSC), in plant samples

Apart from ordinary carbohydrates and sugar alcohols, polysaccharides, such as inulin, polyfructans and starch, are important plant components the composition of which may markedly vary with season, light availability and status of plant growth. Carbohydrate distribution also reflects changes of photosynthetic activity and abiotic stress phenomena, such as drought. In addition to plant physiology, the exact identification and reliable quantification of both polysaccharides and carbohydrates in plant material is of growing importance for the calculation of more sophisticated carbon balances of numerous biogeochemical processes. In this article, a method for the exact determination of polysaccharides of both the starch- and fructan-type is presented. The polysaccharides are split into their monomers by acidic hydrolysis. Whereas hydrolysis of polysaccharides of the fructan-type is carried out under relatively mild conditions using 1% HCl, much harsher conditions are needed for hydrolysis of starch where 30% HClO4 is applied. The hydrolysates are properly diluted and analyzed by high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) for the monomers which are fructose and glucose in case of polyfructans and glucose in case of starch. A highlight of the method is its versatility: the analytical conditions used for the analysis of the polysaccharide hydrolysates are the same as for the carbohydrates and sugar alcohols. Moreover, our method has recently been successfully extended to the quantification of hydroxyethyl starch (HES) in blood plasma