Search results for "humus"
showing 10 items of 117 documents
Short-term effects of wood ants (Formica aquilonia Yarr.) on soil animal community structure
1999
Abstract Wood ants are known to affect the structure of invertebrate communities in tree canopies but it is not clear whether wood ants can affect the structure of soil animal communities. To isolate the direct effects of wood ants on soil fauna, I manipulated wood ant density in a 6-week mesocosm experiment by placing mesocosms (O 14 cm, height 13.5 cm) permeable to ants either on or outside the ant trails. The mesocosms contained litter, humus, and a diverse soil fauna typical of coniferous forest. I controlled earthworm species composition and biomasses by inoculating 470 mg fresh mass of epigeic lumbricid Dendrobaena octaedra (Sav.) or Dendrodrilus rubidus (Sav.) to the mesocosms. A 15-…
Soil decomposer animal community in heavy-metal contaminated coniferous forest with and without liming
2002
Abstract Responses of decomposer animals to heavy-metal contamination were studied near a Cu–Ni smelter in Finland. Samples were taken 0.5, 2 and 8 km from the smelter. In addition, plots fertilised with lime were sampled. Decomposer community in coniferous forest soil appeared to be quite resistant to heavy-metals. Only in the vicinity (0.5 km) of the smelter, were numbers of soil animals clearly decreased and their community structure strongly altered as compared to the control site (8 km). At the 2-km site, the community structure was only slightly changed. Most of the collembolan species were still found at the 0.5-km site. High metal sorption capacity of the humus, and heterogeneous di…
Regulation of decomposer community structure and decomposition processes in herbicide stressed humus soil
1997
Abstract Regulation of soil decomposer community structure and ecosystem processes, such as nutrient cycling, under herbicide stress was studied in a microcosm experiment. For the experiment, coniferous forest soil was defaunated and put into the microcosms. In the microcosms two different food webs including microbes, nematodes, tardigrades and oribatid mites, either with or without predatory mesostigmatid mites, were reconstructed. Half of the microcosms were stressed with a herbicide (active ingredient was terbuthylazine). During the 57 weeks incubation community structure of decomposers and nitrogen mineralisation were studied at five destructive samplings and two water irrigations. Soi…
Monitoring seasonal changes in microbial populations of spruce forest soil of the Northern Temperate Zone
2012
Soil microbial populations in the Northern Temperate Zone have been poorly studied in comparison with extreme environments. The aim of the work was to study the seasonal changes in the microbial populations of spruce forest soil of the Northern Temperate Zone using classical methods of microbiology and molecular biology. Upper horizons in two Picea abies stands on sod- podzolic and illuvial humus podzol soil were analysed. Sampling was done monthly over a period of twelve months (May 2009-April 2010). Microbial communities in both experimental plots showed different responses to the analysed environmental factors. In the sod-podzolic soil only the fungal DNA amount was significantly higher …
Interactions between enchytraeid (Cognettia sphagnetorum), microarthropod and nematode populations in forest soil at different moistures
1998
Abstract Very little is known about the effects of microclimatic conditions on interactions within soil faunal communities. The aim of the experiment was to examine how the different functional components of the faunal community in coniferous forest soil affect each other at different moisture levels. Forest humus was defaunated by heating, adjusted to three water contents, distributed into glass jars and reinoculated with microflora and microfauna. Sets of 10 jars were inoculated with (1) Cognettia sphagnetorum, (2) Cognettia with Folsomia candida (Collembola), (3) Cognettia with a mixed community of microarthropods, (4) Folsomia alone, (5) mixed microarthropods alone, and (6) Cognettia wi…
Concentrations of monosaccharides in humic substances in the early stages of humification.
2001
Deteriorated liquid packaging board (LPB) and biowaste compost are matrices, mainly consisting of cellulose, in the early stages of humification. Degradative studies on these matrices allow an examination of the role of carbohydrates in the synthesis of humic substances. Samples of different age were collected and divided by extraction into hot water extract (HWE), bitumen, humic acid (HA), fulvic acid (FA) and humin or residual fibre fractions. The following monosaccharides were identified in these fractions: L-arabinose, D-ribose, D-xylose, L-fucose, D-mannose, D-fructose, D-galactose, D-glucose, L-rhamnose and xylitol. The main component in all fractions was glucose. The concentrations o…
Alfalfa crops amended with MSW compost can compensate the effect of salty water irrigation depending on the soil texture
2018
The availability of water resources of marginal quality such as drainage water or high-saltcontaining groundwater is turning into an important issue in Tunisia and other countrieswith scarce water resources. A pot experiment was carried out to evaluate plant produc-tion, nutrient content and heavy metal bioaccumulation in agricultural soils amended withMSW compost and irrigated with salty water, by using two different soil textures (clay andsandy). Salt water supply decreased plant dry yield in both soils. Salt stress had signifi-cantly reduction in plant biomass in sandy soil compared to those in clay soil (biomass ofdry weight is significantly higher in clay soil than those in sandy soil …
Distribution of soil animals in patchily contaminated soil
1996
Abstract Distribution of soil animals with respect to patchy chemical contamination was studied in microcosms containing reconstituted coniferous forest floor. Soil materials were defaunated and soil organisms were reinoculated into a mesh basket in the centre of each microcosm. Part of the humus layer was contaminated with three concentrations of sodiumpentachlorophenate (0, 50 or 500 mg PCP kg −1 of dry humus) and put into mesh baskets (two per concentration) around the central patch. No differences in dispersion ability from the reinoculated patch were found between microarthropod species. PCP decreased microbial biomass in the humus. Numbers of collembolans were significantly lower in t…
Sensitivity of soil processes in northern forest soils: are management practices a threat?
2000
Abstract There is evidence that forest management practices influence soil-decomposer communities. It is also established that changes in the trophic structure and composition of these communities can induce changes in soil-nutrient dynamics, thereby affecting plant growth. Whether forest productivity is affected by management-induced changes in, e.g. soil faunal structure, is, however, yet to be shown. The aim of this study was (1) to determine the resolution of the ecological hierarchy (e.g. species, functional groups, trophic levels) at which a change in soil fauna would alter biotically-controlled processes in soils, and (2) to examine the sensitivity of soil fauna of the boreal forest …
Habitat patchiness affects decomposition and faunal diversity: a microcosm experiment on forest floor.
1998
Environmental heterogeneity has been intensively studied, but little is known about relationships between habitat patchiness and soil processes. The aim of this study was to investigate (1) the impact of patchiness of the litter layer on the decomposer community and litter decomposition rate, and (2) whether the impact of soil fauna on the rates of processes differs in relation to patchiness. An experiment was carried out in microcosms with coniferous forest humus and four kinds of litter with different C:N ratios or stages of decomposition, either separately (i.e. in patches) or mixed with each other. Microarthropod species diversity was better maintained in the patchy systems. In the abse…