Über Sorption und Wirkung von Blei auf die biologische Aktivität terrestrischer Humusformen

Lead sorption and effect of lead pollution on biological activity of different types of humus forms Effects of Pb(NO₃)₂ on biological activity (e. g. respiration and enzyme activity) of mull, moder and mor soils were investigated under controlled laboratory conditions. Lead sorption capacity of investigated humus forms decreased in the order mull > moder > mor. Soil respiration was inhibited after addition of 10 mg Pb/g soil at lead concentrations > 1 μg Pb/ml of soil solutions of the mor and moder profiles. Highly significant positive regression coefficients were obtained for decreases in soil respiration and decreases in dehydrogenase-, phosphatase- and arylsulfatase activities of O-horizons. It is assumed that minor enzymatic acitivities after lead addition result from its effect on enzyme producing organisms. After additions of 200 mg Pb/g soil biological activities of investigated humus layers were also affected by a marked increase of acidity of soil solutions. This ?secondary”? effect was also obtained using Ca(NO₃)₂ in pollution experiments.     

Selenitadsorption an Waldhumusformen

Adsorption of selenite on different types of forest humus In the present investigation the adsorption of selenite selenium on L-, O-, and A-horizons of the humus forms mull, moder, and mor was studied. Selenite adsorption decreased in the order mull > moder > mor. The organic layers adsorbed nearly the same amount of selenium as the underlying A-horizons. Among the L- and O-layers selenadsorption increased with increasing pH. Amounts of organic carbon, “free” oxides did not influence the adsorption capacity. The Freundlich equation was valid to describe selenite adsorption of all layers under investigation. Additionally the Langmuir equation fitted the adsorption curves of the mull soil and the moder L-horizon. Adsorption experiments using perfusion apparatuses showed microorganismus to incorporate high amounts of selenite under natural conditions.     

Fluoride-induced changes in chemical properties and microbial activity of mull,moder and mor soils

Summary Fluoride-induced changes of chemical properties and microbial activities in humus soils were investigated in 12-week lysimeter experiments. The mull soil showed the highest F-adsorption capacity, in which 94% of the fluoride added was retained after addition of 4.5 mg F/cm² as NaF. The moder and mor soils only adsorbed 52% and 41%, respectively. F-additions induced leaching of organic matter, Fe, Al and P and increases in soil pH in the moder and mor. In contrast no Al, Fe and P was leached from the mull and only minor amounts of organic matter dissolved after a single application of 4.5 mg F/cm². Treatments with NaF up to 3700 mg F/kg did not significantly reduce respiration in any of the humus forms. Dehydrogenase, alkaline phosphatase and arylsulfatase activities as well as nitrification were inhibited at much lower F-additions in the moder and mor soils. A significant decrease in ammonification was observed in the moder. In contrast, microbial processes in the mull soil were not inhibited. This is due to its high adsorption capacity and the relatively low toxicity of F-ions. According to computations using GEOCHEM, the F-ion was the most abundant species in mull lysimeter leachates. Leachates of moder and mor soils contained mainly AIF-complexes (90%–99%). The lack of any effects from NaF treatment on soil respiration is attributed to the observed positive effects, e.g. dissolution of organic matter, desorption of P and increases in soil pH.     

Structural relationships among vegetation,soil fauna and humus form in a subalpine forest ecosystem: a Hierarchical Multiple Factor Analysis (HMFA)

Aboveground vegetation, four belowground fauna groups and humus composition have been analyzed in order to investigate the links between autotrophic and heterotrophic communities in a Norway-spruce mountain forest in Tours-en-Savoie (France). The aboveground plant community was recorded in small patches corresponding to contrasting microhabitats. Animal communities and humus layers were sampled within the same patches. The relationships between humus profile, faunistic and floristic compositional gradients were investigated by Multiple Factor Analysis (MFA) and, for the first time in ecology, a Hierarchical Multiple Factor Analysis (HMFA) was used to interpret differences among humus layers. The analysis revealed a pattern with three main groups of microhabitats. The thorough study of separate humus layers could explain this result. The interplay of plant–animal–soil interactions is likely to drive the ecosystem toward three alternative states supporting humus traditional classification between mull–mor–moder. HMFA revealed the importance of depth to explain this contrast among humus forms, using humus layers as diagnostic tools in both inert and living components. HMFA also showed contrast between unexploited and exploited parts of the forest, but the study of soil and vegetation indicate that this contrast does not only hold in forest management but also in geomorphology. RV-coefficients among the six groups of variables showed significant fauna–fauna relationships in almost all humus layers except Actinedida. Plant–soil interactions are not as strong as expected and are even weaker when the soil in question is deep. In addition, HMFA failed to show direct interactions between plant and soil fauna but, paradoxically, HMFA does suggest that indirect plant–fauna interactions are at the focus of the ecosystem strategy that leads to the differentiation of ecological niches within the forest mosaic.     

A mathematical model of energy budgets of forest humus of the mull,moder and mor types in Poland

A mathematical solution is proposed of the long-discussed problem of accumulation and decomposition of forest humus, and a generalized form of a dynamic mathematical model of energy budgets of a forest humus layer with any number of subhorizons differing in degree of decomposition is presented. Methods of taking measurements of the relevant parameters for the model are also indicated.The model in question has been applied in analysing the results of detailed studies of energy budgets of forest-floor layers in examples of three climax forest ecosystems with three different types of forest humus (mull, moder, mor).     

Polycyclic Aromatic Hydrocarbons Content in Contaminated Forest Soils with Different Humus Types

The aim of the study was to determine polycyclic aromatic hydrocarbon (PAH) content in different forest humus types. The investigation was carried out in Chrzanów Forest District in southern Poland. Twenty research plots with different humus types (mor and mull) were selected. The samples for analysis were taken after litter horizons removing from a depth of 0–10 cm (from the Of- and Oh-horizon total or A-horizon). pH, organic carbon and total nitrogen content, base cations, acidity, and heavy metal content were determined. In the natural moisture state, the activity of dehydrogenase was determined. The study included the determination of PAH content. The conducted research confirms strong contamination of study soil by PAHs and heavy metals. Our experiment provided evidence that different forest humus types accumulate different PAH amounts. The highest content of PAHs and heavy metals was recorded in mor humus type. The content of PAHs in forest humus horizon depends on the content and quality of soil organic matter. Weaker degradation of hydrocarbons is associated with lower biological activity of soils. The mull humus type showed lower content of PAHs and at the same time the highest biological activity confirmed by high dehydrogenase activity.     

Humus forms in terrestrial ecosystems: a framework to biodiversity

Humus forms are the seat of most biological transformations taking place in terrestrial ecosystems, being at the interface between plants, animals and microbes. The diversity of terrestrial humus forms (mor, moder and mull) can be attributed to the existence of different patterns (strategies) for the capture and use of resources by ecosystems, in ascending order of biodiversity and bioavailability. Arguments are found in the parallel development of humus forms and terrestrial ecosystems, in exclusion mechanisms between organisms living in different humus forms, and in palaeontological studies. The diversification of terrestrial life forms in the course of Earth history, concomitant with an improvement in resource availability due to the development of sedimentary layers at the surface of continents, may explain the successive appearance of more active humus forms enabling the co-existence of an increasing number of organisms. Contradictory reports about the relationships between biodiversity and stability of ecosystems can be explained by the existence of different belowground pathways making ecosystems more stable.     

Sorption und Wirkung von Arsen auf die mikrobielle Aktivität von Waldhumusformen

Arsenate adsorption and effects of arsenate pollution on microbial activity of different types of humus soils Perfusion experiments using Na₂HAsO₄ were carried out in order to investigate adsorption and effects of arsenate on microbial activity of L-, O-, and A-horizons of a mull, a moder, and a mor soil. Arsenic adsorption of mineral A-horizons was positively influenced by their contents of amorphous Al- and Fe-oxides. It is assumed that arsenic was mainly precipitated as Al-, Mn- or Ca-arsenate in the organic layers during the perfusion experiments. The Freundlich equation was valid to describe As-adsorption of all layers under investigation. Microorganisms seemed to be very tolerant to arsenate pollution. Soil respiration and enzyme activities were reduced when liquid concentrations exceeded 8 μg As/ml. Extremely high As-additions (up to 10 mg As/g) did not reduce microbial processes to a greater degree than lower ones of 0,5 mg As/g.     

Vergleichende mikromorphometrische untersuchungen der humusprofile in zwei buchenbeständen

An attempt was made to describe the morphology of humus profiles not only qualitatively but, with stereological methods, also quantitatively, using two examples. The two profiles were situated in a pair of beech forests very close to one another (old stand, BE1, and a thicket by natural regeneration, BE2); aspect and mineral soil were the same.On polished blocks, eleven morphographic features were quantitatively estimated under a stereomicroscope according to seven stereologic methods. Five methods use eyepiece graticules and two methods a semi-automatic image analyzer. The observed features were: number of leaf layers; organic fine material in F- and H-horizons; distinctness of transition from humus cover into mineral soil material; number of horizontal fissu res; leaf residues in Ah-horizon; rootlength density; root volume density, enchytraeid droppings; voids > 20 μm; smooth lobular void boundaries (as traces of earthworm activity); medium sand, coarse sand and stones. The measurements demonstrated that the qualitative differences between the two profile images could be expressed quantitatively to a large extent.The quantitative differences could be interpreted ecologically: low numbers of leaf layers in the old stand, which result from blowing away of the litter, cause frequent desiccation of the soil surface. Thereby the activity of soil animals which mix the organic material into the mineral soil is impeded, and a thin humus cover develops, overlying a dense, fissured mineral soil. The high number of leaf layers in the thicket results from blowing in of litter and of increased litter production at this place. Below the leaf layers, the soil remains moist so that mixing activity of large earthworm species is possible; there are also favourable conditions for voles, which loosen the uppermost part of the soil. On the whole there is a cyclic change of humus forms (between mull and mull-like moder), the primary cause of which is just the change in the tree stand.     

Variation of four phosphorus properties in woodland soils

Variation in total, organic and available-P contents and phosphatase activity of P-deficient soils of some English Lake District woodlands of differing vegetative composition were examined in relation to individual woodlands, two depths in the soil profile, mull, moder and mor humus types, and different times of the year. Depth in the soil profile was a more important source of variation in the P properties than different woodlands. Soils in individual woodlands differed in their degree of variability in the four P properties. Available P contents and phosphatase activities were more variable than total and organic P contents. Available-P and organic-P contents and phosphatase activity showed seasonal variation. Seasonal variation in available-P was almost as great as differences in available-P between woodlands. Total and organic-P contents showed similar patterns of variation with respect to individual woodlands, humus type and soil depth. Differences in degree of variation within woodlands and differences in degree and pattern of variation of the four P-properties may need to be taken into account in soil sampling programmes of studies comparing soils under differing vegetation regimes.Different interpretations of the variation in the soil-P properties were obtained by expressing the data respectively in terms of soil weight (g^?1 soil) or soil volume (cm^?1 soil), due to marked variation in bulk-densities of the woodland soils. It is suggested that where soils vary in bulk-density, soil data should be expressed in terms of soil volume.The P-deficiency of the woodland soils is probably associated with the relatively low total P content per unit volume of soil and the high proportion of it which is organically bound.     

Changes in humus properties and collembolan communities following the replanting of beech forests with spruce

Differences of collembolan communities within the organo-mineral A layer were studied in relation to physico-chemical changes in humus at nine sites of beech forests (Fagus sylvatica L.) and first generation spruce stands (Picea abies (L.) Karst.), planted on former beech forest 30 years ago (Central Pyrenees, France). Changes in humus form were caused by the spruce plantation and occurred mainly within the fermentation horizon where acidifying litter accumulation increased the horizon depth. The recent replacement of beech by spruce induced a shift from mull towards moder humus forms, which is explained by the decreasing organic matter turnover rate. A significant decrease in the three exchangeable cations and pH under spruce was also observed. Collembolan species diversity within the A horizon was significantly lower under spruce at this early stage of the silvogenetic cycle. Differences between species composition of Collembola between the two forest stands is related to changes in environmental conditions (e.g. nutrient availability, soil porosity, soil moisture). This study shows how forest management practices are susceptible to modify biological activity within the A horizon under exotic conifer plantations.     

Cyanidadsorption an Sesquioxiden,Tonmineralen und Huminstoffen

Cyanide adsorption on sesquioxides, clay-minerals and humic substances The adsorption of cyanide (KCN) on sesquioxides, clay minerals, and humic substances at different pH-values was studied. Moreover we looked for the CN-adsorption on L-layers of the humus forms mull, moder and mor. Cyanide was only adsorbed by humic acid. The amount of CN adsorbed increased with increasing pH of the reaction solution. IR-spectroscopic investigations of CN treated humic acids revealed that the cyanide was adsorbed at low pH (<7) as HCN-molecules by formation of hydrogen bonds with COOH-, COH-, OH- and NH₂-groups of the humic acid. At pH > 7 the cyanide was mainly adsorbed as CN^? by charge transfer with acceptor-molecules such as chinones. The cyanide adsorption of L-layers of humus forms decreased in the order mor > mull > moder. It is surmised that the HCN-molecules were not only adsorbed by humic acids in these layers but also by oxidation products of lignin, pectin, protein, cellulose, and carbon-hydrates of fulvic acids. Solutions of K₂HPO₄ did not desorb cyanides from humic acids to any great extent.     

Effects of sodium selenite on microbial activity of mull,moder and mor soils

Summary Effects of Na₂SeO₃ on microbial activity of mull, moder and mor soils were investigated with perfusion experiments under controlled laboratory conditions. Treatments with Se at 50 mg/kg reduced carbon dioxide production and dehydrogenase activity in the mor and moder soils. Se at 250 (Ah) to 1000 (L) mg/kg had to be added to the mull soil in order to affect both parameters. In contrast to the effect on respiration and dehydrogenase activity, N mineralization, especially ammonification, was stimulated by the addition of Se. This is probably due to secondary effects such as dissolution of organic matter and P desorption. The relative inhibition of arylsulfatase activity was closely correlated with a decrease in soil respiration. It was conduded that the reduction of arylsulfatase activity in Se-treated soils was the result of a reduction in enzyme synthesis.     

Humus forms and metal pollution in soil

Smelters in northern France are a serious source of soil pollution by heavy metals. We have studied a poplar plantation downwind of an active zinc smelter. Three humus profiles were sampled at increasing distance from the smelter, and the thickness of topsoil horizons was measured along a transect. We analysed the vertical distribution of humus components and plant debris to assess the impact of heavy metal pollution on the humus forms and on soil faunal activity. We compared horizons within a profile, humus profiles between them, and traced the recent history of the site. Near the smelter, poplar trees are stunted or dead and the humus form is a mor, with a well‐developed holorganic OM horizon. Here faunal activity is inhibited, so there is little faecal deposition and humification of plant litter. At the distant site poplar grows well and faunal activity is intense, so there are skeletonized leaves and many organo–mineral earthworm and millipede faecal pellets. The humus form is a mull, with a well‐developed hemorganic A horizon. The passage from mor to mull along the transect was abrupt, mor turning to mull at 250 m from the smelter, though there was a progressive decrease in heavy metal deposition. This indicates that there was a threshold (estimated to be 20 000 mg Zn kg^?1) in the resilience of the soil foodweb.     

Annual population dynamics and production ecology of Testacea (Protozoa,Rhizopoda) in an aspen woodland soil

The population studies of Testacea in an aspen woodland soil revealed 28 taxa of living Testacea, 14 of which were considered constant. The 14 species, while comprising 98 and 96% of the mean annual density and total annual production numbers respectively, accounted for only 80% of the mean annual biomass and 86% of the total annual production biomass. All 14 species had a peak in abundance in autumn, immediately or soon after leaf litter fall. While most species maintained small, active and reproducing populations over the winter period, some maintained higher than normal densities, had seasonal peaks in abundance and biomass, or higher than normal rates of production and turnover. All species had an increase in reproduction and usually in abundance also during the late winter-early spring period before spring thaw. The annual mean weekly density and biomass and the annual production totals tor numbers and biomass were highest in the H layer and lowest in the L. The F layer produced the highest numbers of generations per year and the highest annual mean weekly biomass turnover rate for most of the species. The majority of the periods of high intrinsic rate of natural increase, biomass production and turnover occurred during or after an increase, a decrease or a stabilization in soil moisture content. Mean annual biomass and total annual production were estimated as 0.72 and 206 g wet weight m^?2 respectively. The aspen woodland soil Testacea (in a mor humus) had a much higher production and number of generations per year than Testacea from mull and moder humus forms.Total annual ingestion, respiration losses and egestion losses for testate amoebae in an aspen woodland soil were calculated as 1377, 344 and 826 g wet weight of biomass m^?2, respectively. The annual secondary production of Testacea was about 250–300 times the standing crop of Testacea in all the soil layers. The dry weight of carbon respired per year by the Testacea was estimated as 16.2 g m^?2, which amounted to about 6% of the total carbon input.     

Auswirkungen einer Temperaturerhöhung in einem Freilandexperiment auf den Stickstoffaustrag aus Bodensäulen mit verschiedenartiger Humusform

Effects of a temperature increase in a field experiment on the nitrogen release from soil cores with different humus forms Global warming could have far-reaching consequences for the properties of soils. From the available knowledge it is postulated that an increase in temperature (all other climatic conditions unchanged) will decrease the nitrogen contents until a new equilibrium is reached. To test this hypothesis we established in the ‘Tegernsee Alps’ a field experiment. In spruce-dominated montane forests 60 undisturbed soil cores (= monoliths) were carefully digged out at 1250 and 1320 m asl and reestablished at 3 elevations (1250 m and 1010 m and at 740 m asl) corresponding to a warming of around 1 and 2°C. At each slope position we investigated a Dystric Cambisol with raw humus (RH) and another one with moder (MO). Each of these 6 trial-variants therefore was represented by 10 monoliths. From August 1992 to December 1995 seepage water was sampled by suction cups every 2 or 4 weeks and analyzed for the concentrations of important bioelements including aluminum, pH and electrical conductivity. After translocation to warmer climates additional nitrogen was released from both soil forms mainly as nitrate. The cambisol with the more active humus form moder reacted stronger than the one with raw humus (additional output > 40 vs. 34 kg ha^?1 a^?1; +2°C). In both soil forms the N release was accelerated in summer, in RH by 55 to 92 and in MO by 37 to 86 ppm. The Cambisol with moder showed higher nitrate leaching also in winter and thus was superior with regard to the total annual N output. In all cases Al was the most important associated cation to NO₃^? with 75% (RH) and 54% (MO) of the cation equivalent sum respectively. The experiment thus confirms a substantial increase of nitrification even by a temperature increase of only 1 and 2°C, which in permeable, well aerated soils should lead to increased nitrate leaching under conditions where no vegetation is interfering.     

The heterogeneity of humus profiles and earthworm communities in a virgin beech forest

Thirty sites, encompassing a range of soil and vegetation conditions in the biological reserve of La Tillaie (Fontainebleau Forest, France) were investigated in April 1992. Beech (Fagus sylvatica L.) was the dominant tree species, with several developmental phases forming the forest patchwork. Sessile oak [Quercus petraea (Mattus.) Liebl.] was present but only as old relictual individuals. Gaps in the canopy cover were abundant, mostly caused by wind storms 2 years previously. The next most recent storm was 25 years before, resulting in distinct patches of full-grown trees. Humus profiles were classified and compared with the distribution of earthworm communities, canopy cover, and soil types. Geomorphology was responsible for the main part of the observed variation. Absence of lime in the substrate and direct contact with a sandstone stratum near the ground surface was associated with the absence of earthworms and the appearance of an OH horizon (moder humus). Elsewhere, earthworms were present and humus profiles did not display any OH horizon (mull or mull-like moder humus), but species composition was variable and strongly influenced by the thickness of the superficial sand deposit overlying limestone. On a thick (1 m or more) sandy substrate earthworm communities were dominated by epigeic species together with the anecic Lumbricus terrestris L. The species richness was higher on a shallower sandy substrate (50 cm) where lime was more accessible to tree roots and burrowing animals. The influence of the forest cycle of beech was visible in the latter case (covering most of the area), with an increase in the thickness of the OL and OF horizons and a decrease in endogeic earthworm populations during the phase of intense growth of beech. This fall in burrowing activity was apparent in gaps created by wind storms and fungal diseases within mature stands as early as 2 years after the fall of the trees.     

Litter decomposition and humification in acidic forest soils studied by chemical degradation,IR and NMR spectroscopy and pyrolysis field ionization mass spectrometry

Two forest soils (Typic Dystrochrept, Entic Haplorthod) with mor and moder were investigated by chemical degradation, IR and CPMAS ¹³C NMR spectroscopy and pyrolysis (Py) field ionization (FI) mass spectrometry (MS). Chemical analyses show that during litter decomposition, humification, and podzolisation, cellulose and lignin structures decrease considerably, whereas no distinct changes were found for the hemicellulose and protein fractions. These results are consistent with current hypotheses on the conversion of plant residues to stable humic substances, but the sum of chemically identified organic soil components of the litter layers only accounts for 40–50% of total organic carbon. The amounts of different carbon types were estimated by the integration of CPMAS ¹³C NMR spectra. For the L layers this calculation assigns 56–58% as O-alkyl-C, 20–22% as alkyl-C, 14–16% as aryl-C, and 6–8% as carboxyl-C. With increasing soil depth O-alkyl-C (with polysaccharides as main source) decrease to 31–42%, aliphatic C increases to 36–43%, and aryl- and carboxyl-C show no distinct changes. The hypothesis of an increasing aromaticity during humification in soils therefore is questionable. Data from Py-FIMS confirm and extend the results' of chemical methods as well as IR and ¹³C NMR spectroscopy. In particular, the Fi mass spectra of the generated pyrolysates show that the increase in polymethylene carbon during the biodegradation and humification of beech and spruce litter is partly due to an increase of saturated fatty acids. This means, Py-FIMS is able to describe the structure of wet-chemically unaccounted, individual humus constituents and thus improves the knowledge about the genesis of humic substances.     

庐山山地垂直自然带土壤腐殖质与土壤动物分布特征

沿庐山垂直自然带谱对常绿阔叶林（低海拔,L）、落叶常绿混交林（中海拔,M）和落叶阔叶林（高海拔,H）地面腐殖质及大中型土壤动物分布情况进行调查分析,使用调查数据探究了该垂直自然带土壤腐殖质与土壤动物分布特征。调查分析的腐殖质指标有剖面各发生层厚度、O-A过渡层厚度以及A层土壤团粒大小和有机质、总碳量、全磷、全氮、全碳含量和pH值等,土壤动物指标有类群数、个体密度和多样性指数。结果表明,L、M、H自然带地面腐殖质分别以细腐殖质（Mull）、半腐殖质（Moder）和粗腐殖质（Mor）为主;调查共获得隶属于3门8纲24目的大中型土壤动物2636头,其平均密度为2245.23 ind m?2,优势类群前气门亚目、甲螨亚目、弹尾目动物个体数分别占总个体数的38.87 %、25.36 %和13.37 %。皮尔逊相关性分析和典范对应分析（CCA）结果表明,土壤动物个体密度与A层土壤养分含量、类群数与O层厚度关系密切,而多样性指数既与A层土壤pH值、也与A层土壤养分含量及O-A过渡层厚度密切相关。土壤动物分布总体特点是优势类群在不同腐殖质组型土层广泛分布,而常见类群和稀有类群则分别与腐殖质组型中的OH层厚度、OL层厚度关系密切。