Humus layer

Kogel, I. (1986). Estimation and decomposition pattern of the lignin component in forest humus layers. Soil Biology and Biochemistry 18 589-594. 

Kogel, I. and Bochter, R. (1985). Characterization of lignin in forest humus layers by high-performance liquid chromatography of cupric oxide oxidation products. Soil Biology and Biochemistry 17 637-640. 

In soils of non-agricultural ecosystems, above ground biomass (foliar uptake) and metal cycling is considered important (see Figure 8), due to large impact on the metal distribution in the humus layer and mineral soil profile. Especially in soils of Forest ecosystems, it may affect the accumulation in the humus layer, which is considered a very relevant compartment regarding the calculation of a critical load. In these soils, however, a steady-state element cycle is assumed, which implies that mineralization, Minj, equals litterfall, Mjf. 

Much of the Hgt pool was found in the upper part of the soil, which is rich in organic matter. This pattern is likely due to an elevated atmospheric deposition of Hgt over the extended period and immobilization of mercury by organic functional groups and accumulation of organic matter as part of the soil-forming process. The retention of mercury in the mor humus layer was almost complete due to the very strong association between Hgt and humic substances. 

Disturbance may influence the allelochemlcal environment in various ways. Living biomass is reduced, and fire reduces or eliminates litter and humus layers as well. Hence we should expect the total production of allelochemlcals to be lowered following disturbance. As succession proceeds and total biomass and litter layers rebuild. 

Kormos excavated in the shelter in 1914. Below the humus layer there was (1) a yellowish cave clay with limestone rubble ( Upper layer ) and (2) beneath it, reddish-brown clay ( lower layer ), from which, together with Lambrecht, he identified the... 

Nilsson and Wallander (2003) incubated soil cores in the field to estimate the influence of nitrogen fertilization on ectomycorrhizal biomass in a Norway spruce forest in southern Sweden. Ectomycorrhizal biomass in the humus layer declined from 800 kg ha to 300 kg ha after adding 100 kg N ha yr for 10 years. These estimates of ectomycorrhizal biomass in soils of Swedish forests are much larger than the amounts present in similar forests as... 

Regional distribution of selenium and arsenic in humus layers of Norwegian forest soils. Geoderma , 20, 3-14 (1978). 

The distribution of fine roots in the various soil horizons can be used as a good indicator of root health. Root development is considered as very poor in soil layers containing 1 to 2 fine roots per dm. 5 to 10 fine roots per dm or 10 to 20 fine roots per dm are regarded as a mean or strong root development respectively. Dying root tips, for example at the border between humus layer and mineral soil hint at toxic soil conditions in the lower horizon (see Fig. 4). 

Ol — Litter layer Op — Fermentation layer — Humus layer... 

Border line between humus layer and mineral soil = 0 om. 

Describe the role of soil organic matter in biogeochemical processes. Why can the upper humus layer be considered as biogeochemical barrier ... 

Humus layer Clark Humus layer Clark Humus layer Clark... 

Dahl, E., Gjems, O., and Kjelland-Lund, J. Jr. (1967). On the vegetation of Norwegian conifer forest in relation to the chemical properties of the humus layer. Medd. Norsk Skogsforsoksv. 85, 501 - 531. 

I N-contents, f Mineralization, f N-tiirnover, NPP, N surplus, I Mycorrhiza, f /1 Humus layer... 

Kogel-Knaber, 1., Hempfling, R., and Schulten, H.-R., Decomposition in forest humus layers studied by CPMAS C NMR, pyrolysis-field ionization-MS and CuO oxidation, Sci. Total Environ., 62, 111-113, 1987. 

Tab. 4.1 Carbon and nitrogen content in the humus layer and mineral soil of a gneiss-podzol-brownearth (Spodic-Dystric Cambisol) under a mixed spruce-beech-stand in the Tharandt Forest. Humus type raw humus-like moder. (After Fiedler et al. 1994.)...

Fig. 4.1 Nitrogen in the humus layer and mineral soil above different parent rocks in the Eastern Ore Mountains. After Klinger (1995).

Clarholm, M. (1 993) Microbial biomass-P, labile-P, and acid-phosphatase-activity in the humus layer of a spruce forest, after repeated additions of fertilizers. Biology and Fertility of Soils 16, 287-292. 

In Finland, for example, where typical podzols are predominant, the forest soils have a humus layer of varying thickness with even larger amounts found in the upper portion of the mineral soil. Viro (1963) states that over 95% of the tree roots are found in the humus layer and the upper foot of mineral soil. In south Finland the humus layer of the... 

Organic mater is a source (short-term and long-term storage) of nutrients for plants and soil microbes. Organic matter often has a negative charge associated with the humus layer that attracts cations (which can be used as nutrients), metals, and pesticides. 

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