Humus profiles of mountain-chestnut soils of a complex catena in Central Tuva

The paper analyzes humus profiles of mountain-chestnut soils of a complex catena situated within the Khemchik dry-steppe area of the Central Tuva Depression. The study has shown that humus profile characteristics are determined by both slope aspects and position in the catena. Humus profiles imprint all environmental changes of soil formation and functioning even if these changes are not expressed in soil morphology. The materials obtained during the study may serve as basis for long-term monitoring of slope soil behavior and for revealing local soil variability in changing environment.     

A comparative study of soil formation in primary stands of Scots pine (planted) and poplar (natural) on calcareous dune sands in the Netherlands

Initial soil formation under primary stands of Scots pine (planted) and European black poplar (natural) on calcareous dune sands was studied, paying particular attention to the humus forms and their spatial variability. The stands studied are both about 80 years old and are situated, at close distance, in the coastal dunes near Wassenaar (the Netherlands).Under Scots pine, soils with a mor-type humus form were observed, exhibiting slight podzolisation. Soil variability is rather slight and soil development is comparable to that under primary Scots pine stands on non-calcareous inland drift sands. Under poplar, mull-type humus forms occur which tend towards moder and exhibit a markedly stronger litter decomposition and bioturbation. In contrast to the soils under pine, soil variability is considerable. Results from chemical analyses of two representative soil profiles are in conformance with these trends.It is concluded that the observed trends in soil formation are in line with those described in the literature, and that a period of 80 years is sufficient for a strong vegetation related divergence in soil properties. Soil variability within the stands probably results from redistribution of litter by wind and/or gravity and will be rather site-dependent.     

Humus Form Development during Forest Restoration in Exclosures of the Tigray Highlands, Northern Ethiopia

Forest restoration in protected exclosures has become a common practice to fight land degradation in the highlands of northern Ethiopia. Insights into ecosystem processes governing restoration in these formerly degraded areas are gained through the study of humus forms and factors influencing humus formation during vegetation recovery. Humus forms of 135 sample plots located in different land use types were morphologically described. The subsequent classification into six humus form types was based on principal component analysis and cluster analysis. Where areas are closed for a longer time, humus profiles are commonly more developed and higher organic matter accumulation is noticed as well as increased nutrient stocks. The combined effects of seasonal drought conditions and low fresh litter quality account for an overall slow decomposition, which explains the high importance of litter input for organic matter accumulation. Based on a correlation analysis, vegetation cover, litter production, litter quality, soil nutrient content, soil moisture, and topography were identified as important factors influencing humus formation. It is inferred that humus formation leads to improvements in soil fertility and structure, microclimate development, and soil protection and therefore forms part of the restoration processes taking place in exclosures.     

Soil reproduction in steppe ecosystems of different ages

Features of the development of steppe chernozems were established based on the study of soils of different age groups at archaeological sites. Differences in the formation of phytomass and morphological maturity of the soil profile in the recovery of different age successions were shown. A regional model of the humus horizon steppe soil over time allowed us to estimate the time interval at which the processes of humus accumulation and morphological maturity of the soil profile are relatively at equilibrium, viz., 1700–1900 years.     

Effects of Pinus sylvestris root growth and mycorrhizosphere development on bacterial carbon source utilization and hydrocarbon oxidation in forest and petroleum-contaminated soils

The hypothesis that Pinus sylvestris L. root and mycorrhizosphere development positively influences bacterial community-linked carbon source utilization, and drives a concomitant reduction in mineral oil levels in a petroleum hydrocarbon- (PHC-) contaminated soil was confirmed in a forest ecosystem-based phytoremediation simulation. Seedlings were grown for 9 months in large petri dish microcosms containing either forest humus or humus amended with cores of PHC-contaminated soil. Except for increased root biomass in the humus/PHC treatment, there were no other significant treatment-related differences in plant growth and needle C and N status. Total cell and culturable bacterial (CFU) densities significantly increased in both rhizospheres and mycorrhizospheres that actively developed in the humus and PHC-contaminated soil. Mycorrhizospheres (mycorrhizas and extramatrical mycelium) supported the highest numbers of bacteria. Multivariate analyses of bacterial community carbon source utilization profiles (Biolog GN microplate) from different rhizosphere, mycorrhizosphere, and bulk soil compartments, involving principal component and correspondence analysis, highlighted three main niche-related groupings. The respective clusters identified contained bacterial communities from (i) unplanted bulk soils, (ii) planted bulk PHC and rhizospheres in PHC-contaminated soils, and (iii) planted bulk humus and rhizosphere/mycorrhizosphere-influenced humus, and mycorrhizosphere-influenced PHC contaminated soil. Correspondence analysis allowed further identification of amino acid preferences and increased carboxylic/organic acid preferences in rhizosphere and mycorrhizosphere compartments. Decreased levels of mineral oil (non-polar hydrocarbons) were detected in the PHC-contaminated soil colonized by pine roots and mycorrhizal fungi. These data further support our view that mycorrhizosphere development and function plays a central role in controlling associated bacterial communities and their degradative activities in lignin-rich forest humus and PHC-contaminated soils.     

Diversity of soil mesofauna in northern taiga biogeocenosises of the Kamennaya River basin (Karelia)

The population of soil mesofauna in the basin of the small river subzone of the northern taiga (Karelia) has been investigated. It was shown that indexes of the number and mass of soil mesofauna in the landscape-ecological row of biogeocenosises are maximal in floodplain soils. The taxonomic composition and structure of domination of the soil mesofauna population depends on the location of biogeocenosis in the landscape: earthworms are dominants in riverine floodplain biogeocenosises, and larvae of elaterids and spiders prevail in the places outside of floodplains. The abundance of saprophytic invertebrates in floodplain biogeocenosises results in formation of humus of the mull type. A group of animals with mixed type of nutrition dominates in the places outside of floodplain soils that are related with humus of the moder-mor type. The population of rove beetles (Staphylinidae) allows the division of biogeocenosises into two groups according to their position in the landscape.     

Maintenance and Impacts of an Inoculated mer/luc-Tagged Pseudomonas fluorescens on Microbial Communities in Birch Rhizospheres Developed on Humus and Peat

Antagonistic bacteria represent promising biocontrol agents for improving forest production in seedling nurseries or forest soils. The fate of an introduced mer/luc-tagged antagonistic Pseudomonas fluorescens 31K3 was monitored in the rhizosphere of silver birch (Betula pendula) seedlings grown in microcosms containing forest humus or nursery peat. The inoculated strain (10(8) cfu g(-1) soil) was unable to establish in significant numbers in either soil type and turned nonculturable in humus. Detection in both soils was possible only via luminescence of enrichment cultures 80 days post-inoculation. Despite low P. fluorescens survival, inoculation had a positive effect on seedling growth. Limited impact of inoculation on the indigenous microbial communities was identified following analyses of respiration and denitrification potential, community-level physiological profiles and molecular fingerprinting of fungi and eubacteria, and Pseudomonas community structures. The minor changes observed in the indigenous microbial communities, including mycorrhiza development, were not consistent between humus and peat growth substrates. It was concluded that the rhizosphere-related microbial communities developed in both of these highly organic soil systems are highly buffered against introduction of foreign bacteria.     

土壤保肥-供肥机理及其调节Ⅱ.棕壤型菜园土的腐殖质结合形态及其肥力学意义

采自辽宁省不同地区的１５对棕壤型菜园土肥、瘦地及其各粒级微团聚体的有机质储量和腐殖质结合形态的研究表明,肥地及其各粒级微团聚体的有机质和各结合形态腐殖质的含量与松结态腐殖质占有机质总量的比例均比瘦地及其各相应粒级微团聚体的高,稳结态腐殖质的比例较小,紧结态腐殖质的比例肥瘦地大体相当．无论肥地或瘦地,小粒级微团聚体的有机质和各结合形态腐殖质的含量及松、稳结态腐殖质占有机质总量的比例均较大粒级的高,而紧结态腐殖质则相反,表明大、小粒级微团聚体具有不同的肥力学意义     

16S rRNA gene analyses of bacterial community structures in the soils of evergreen broad-leaved forests in south-west China

Bacterial community structure was studied in humus and mineral soils of evergreen broad-leaved forests in Ailaoshan and Xishuangbanna, representing subtropical and tropical ecosystems, respectively, in south-west China using sequence analysis and terminal restriction fragment length polymorphism (T-RFLP) analysis of 16S rRNA genes. Clone sequences affiliated to Acidobacteria were retrieved as the predominant bacterial phylum in both forest soils, followed by those affiliated to members of the Proteobacteria, Planctomycete and Verrucomicrobia. Despite higher floristic richness at the Xishuangbanna forest than at the Ailaoshan forest, soil at Xishuangbanna harbored a distinctly high relative abundance of Acidobacteria-affiliated sequences (80% of the total clones), which led to a lower overall bacterial diversity than at Ailaoshan. Bacterial communities in humus and mineral soils of the two forests appeared to be well differentiated, based on 16S rRNA gene phylogeny, and correlations were found between the bacterial T-RFLP community patterns and the organic carbon and nutrient contents of the soil samples. The data reveal that Acidobacteria dominate soil bacterial communities in the evergreen broad-leaved forests studied here and suggest that bacterial diversity may be influenced by soil carbon and nutrient levels, but is not related to floristic richness along the climatic gradient from subtropical to tropical forests in south-west China.     

Ectomycorrhizal development on Scots pine (Pinus sylvestris L.) seedlings in different soils

In the present study ectomycorrhizal development of Laccaria bicolor, Rhizopogon luteolus and Suillus bovinus associated with Scots pine (Pinus sylvestris) seedings was studied as affected by primary stand humus, secondary stand humus, podsolic sandy soil or peat in perspex growth chambers. After 9 weeks, ectomycorrhizal development with S. bovinus was significantly greater in peat and primary stand humus than in secondary stand humus or podsolic sandy soil. Ectomycorrhizal development with R. luteolus in secondary stand humus was higher than in primary stand humus. Degree of ectomycorrhizal development of L. bicolor, R. lutuelus and S. bovinus on Scots pine was related to potassium concentration, organic matter content and pH of the soils suggesting that chemical composition of the soils affects ectomycorrhizal development.     

黄土高原典型区域土壤腐殖酸组分剖面分布特征

黄土高原作为典型的气候敏感带和生态环境脆弱区,诸多因素影响着这个区域的土壤有机碳及其组分的分布特征。本文以黄土高原典型区域土壤剖面 0—200 cm土样为对象,分析了土壤腐殖酸、胡敏酸（HA）和富里酸（FA）含量随地理位置及土层深度的分布特征,并进一步探讨了土壤腐殖酸、HA和FA与全氮含量及土壤颗粒组成的关系。结果表明,黄土高原主要类型土壤腐殖酸、HA和FA含量均较低,且存在明显地理位置和土层分异性：从南到北同层次土壤腐殖酸、HA和FA含量均显著降低,同一区域随土层深度增加各组分含量均表现为在 0—40 cm土层明显下降, 40—120 cm土层稍有下降,120 cm土层以下基本稳定;土壤腐殖酸占有机碳比例变化范围为26.6%—54.7%,相对较小,且在整个剖面变化幅度不大,从南向北土壤腐殖酸占有机碳比例有增加趋势;土垫旱耕人为土在 0—40 cm、 40—120 cm和 120—200 cm土层中HA占腐殖酸比例分别为39.8%、49.0%和53.5%,HA/FA分别为0.66、0.96和1.15,黄土正常新成土在以上土层中HA占腐殖酸比例分别为26.3%、33.9%和42.3%,HA/FA分别为0.36、0.51和0.73,干润砂质新成土在以上土层中HA占腐殖酸比例分别为13.4%、37.1%和45.2%,HA/FA分别为0.16、0.59和0.82,说明黄土高原南北主要类型土壤腐殖酸品质总体较差,均属富里酸型土壤,且从南到北腐殖酸品质逐渐下降;土壤腐殖酸、HA和FA均与全氮含量呈极显著线性相关（P<0.01）,土壤有机碳、腐殖酸及HA含量与粘粒及砂粒百分含量亦呈高度线性相关（P<0.01）。     

Influence of agricultural soil management on humus composition and dynamics: Classical and modern analytical techniques

In-source pyrolysis-field ionization mass spectrometry (Py-FIMS), in combination with complementary elemental, wet-chemical, biochemical, and microbiological data, has been used to characterize humus composition and dynamics in soil samples from several field plots that have been cultivated in long-term experiments under different management conditions. Thermograms and Py-FI mass spectra of whole-soil samples from field plots that under very different management show significant differences in humus composition, which may be due to varying stages of decomposition of plant residues and humus genesis. The intensity of soil management significantly affects high-molecular-weight subunits such as dimeric lignin0, arylalkyl-, and aliphatic constituents, even though humus quantity is similar for plots under more practically oriented management, such as crop rotation. The differences in molecular humus subunits of soil samples from different plots, in combination with complementary data, demonstrated that less parent (i.e. primary) material is incorporated in the humus matrix under intense soil management conditions. Samples from different field plots can thus be objectively differentiated on the basis of humus properties using multivariate statistical techniques such as principal component and cluster analyses. This statistical discrimination, using Py-FI mass spectra of the samples, corresponds well with microbial biomasses but is somewhat inconsistent with elemental data and results of chemical degradation procedures. The microflora populations in soils under intense management are limited by low availability and/or quality of carbon substrates. The resulting restricted internal nitrogen cycle causes those soils to have a reduced capacity to immobilize N, leading to relative enrichment of heterocyclic nitrogen compounds that are resistant to mineralization.     

The ecology of keratinophilic fungi at different depths of soil.

The influence of depth and humus content of soil, on the presence of keratinophilic fungi in 4 layers (1-10 cm, 11-25 cm, 26-40 cm, 41-55 cm) of carbonate meadow, chernozem carbonate meadow and carbonate alluvial soils was studied. Different keratinophilic fungi were found not only in individual soils but also in different layers of the same soil. The greatest number and quantity occurred in soil with highest humus content. These fungi were present in greatest amount in the superficial layers (1-10 cm and 11-25 cm) of all soils investigated.     

半干旱黄土丘陵区纯林土壤腐殖质异化特征及与其他性质的关系

纯林长期生长或多代连栽必然会导致土壤腐殖质含量和构成发生异化,探究这种异化特征及其与土壤其他性质的关系可以为纯林管理或混交改造提供科学依据。通过对半干旱黄土丘陵区南泥湾林场8种典型纯林土壤腐殖质及其他性质进行系统检测,结果表明:(1)侧柏林土壤腐殖质含量最高(34.61 g/kg),腐殖化程度和稳定性一般;白榆和白桦林土壤的腐殖质含量中等(19.69—23.58 g/kg)、腐殖化程度和稳定性最佳;茶条槭和小叶杨林土壤的腐殖质含量(20.59—22.53 g/kg)和构成均为中等水平;油松、沙棘和刺槐林土壤的腐殖质质量较低(11.77—13.81 g/kg),且腐殖化程度较低,稳定性相对最差;(2)与胡敏酸含量存在显著相互促进作用(P0.05)的土壤性质为CEC、N、微生物量和蛋白酶活性(相关系数0.769—0.926,下同),存在显著相互抑制作用的为有效Cu(-0.793);与富啡酸存在显著相互促进作用的为N、CEC、微生物量、蔗糖酶和磷酸酶活性(0.836—0.955),存在显著相互抑制作用的为有效Cu(-0.822);与胡敏素存在显著相互促进作用的为N、CEC、微生物量、磷酸酶活性和有效Zn(0.766—0.951),存在显著相互抑制作用的为脱氢酶活性(-0.784)。(3)腐殖质构成与其他性质的相关性均不显著(P0.05),其中相对有利于提高胡敏酸/腐殖酸含量之比的土壤性质为蛋白酶、蔗糖酶和过氧化氢酶活性,而不利的是脱氢酶活性;相对有利于提高胡敏酸/富啡酸含量之比的为速效K、CEC和脲酶活性,而不利的是脱氢酶活性。(4)总体而言土壤腐殖质含量较之腐殖质构成与其他性质之间具有更大的相关性;向土壤增施N肥可以促进腐殖质的形成,增加K肥则有利于腐殖质构成的改善,而通过混交改造或增加林下植被是促进纯林土壤腐殖质化过程和解决土壤退化的根本措施。     

内蒙半干旱低山区不同纯林土壤腐殖质分异特征及其与其他生物化学性质的关系

纯林土壤腐殖质含量及其构成是否会因枯落叶组成的单一性和单优群落环境的特殊性而发生分异变化是关系到森林可持续经营的关键问题.本文以内蒙半干旱低山区的6种典型纯林为研究对象,研究了不同树种纯林土壤腐殖质分异特征及其与其他生物化学性质的关系.结果表明：云杉和白桦林地土壤的腐殖质含量、缩合程度和稳定性均较高,其次为小叶杨和落叶松林地,再次为白榆林地,而油松林地土壤的腐殖质含量和缩合程度均最低、稳定性最差.土壤微生物生物量和磷酸酶活性与腐殖质各组分的积累及其稳定性存在相互促进作用;过氧化氢酶和脱氢酶活性则与土壤腐殖质存在相互抑制作用,且脱氢酶活性的提高可能破坏腐殖质的稳定性.速效N含量与腐殖质积累及其稳定性呈正相关,而全量Cu、Fe、Zn含量与腐殖质呈负相关,全Cu、Fe的增加可能会破坏腐殖质的稳定性.纯林环境及其枯落叶性质的特殊性是造成腐殖质分异的重要原因,混交改造或增加林下植被是改善土壤腐殖质构成的根本措施.     

Differentiating chernozemic soil organic matter by acriflavine adsorption

Summary 1. Acriflavine adsorption capacities of humic substances are not easy to interpret since factors such as acid pretreatment, strength of extractant, and time and temperature of extraction all affect the data. It is thus difficult to establish with this technique whether qualitative differences exist between organic matter formed under different plant associations. 2. Acriflavine sorption capacity of the acid-precipitable humus extracted may be a measure of the efficiency of humus carbon extraction as related to the organo-mineral complexes in the soil since it correlates negatively with the clay content of the samples. 3. Acriflavine adsorption values of the acid-precipitable humus of the aeolian soils are likely to represent true or total sorption capacities of this fraction in these soils, because the clay content of these soils is low and thus extraction of those sites responsible for the acriflavine sorption reaction will be more complete.     

Original humus forms in a semi-deciduous tropical forest in Guadeloupe

Humus profiles underneath the canopy of dominant tree species in two secondary semi-evergreen forest sites in Grande-Terre (Guadeloupe) were analysed with a micromorphological method. In the vertisol of a tree plantation, the humus formed was rather similar under all tree species being an eumull and essentially due to the activity of the endoanecic earthworm Polypheretima elongata. In a natural secondary forest located on a steep slope and associated with a rendzina soil (without endoanecic earthworms), the humus forms were described at lower, mid- and upper slope. In this forest, two particular humus forms were observed. At the middle slope, underneath the canopy of Pisonia subcordata L. that produces nitrogen-rich litter, a calcareous amphimull, characterised by an OH horizon made of millipede faecal pellets, was formed. In the upper slope, underneath the canopy of Bursera simaruba (L.) Sarg. that produces a litter rich in resins and aromatic compounds that are poorly consumed by soil animals, a dysmull with a thick root mat (OFRh horizon) developed. Other humus forms were intermediate. The formation of these humus forms is discussed.     

Ecological and site historical aspects of N dynamics and current N status in temperate forests

Ecological developments during Holocene age and high atmospheric depositions since industrialization have changed the N dynamics of temperate forest ecosystems. A number of different parameters are used to indicate whether the forests are N‐saturated or not, most common among them is the occurrence of nitrates in the seepage water below the rooting zone. The use of different definitions to describe N saturation implies that the N status of ecosystems is not always appropriately assessed. Data on N dynamics from 53 different German forests were used to classify various development states of forest ecosystems according to the forest ecosystem theory proposed by Ulrich for which N balances of input – (output plus plant N increment) were used. Those systems where N output equals N input minus plant N increment are described as (quasi‐) Steady State Type. Those forests where N output does not equal N input minus plant N increment as in a ‘transient state.’ Forests of the transient state may lose nitrogen from the soil (Degradation Type) or gain nitrogen [e.g., from atmospheric depositions (Accumulation Type)]. Forest ecosystems may occur in four different N states: (a) (quasi‐) Steady State Type with mull type humus, (b) Degradation Type with mull type humus, (c) Accumulation Type with moder type humus, and (d) (quasi‐) Steady State Type with moder type humus. Forests with the (quasi‐) steady state with mull type humus in the forest floor (n= 8) have high‐soil pH values, high N retention by plant increment, high N contents in the mineral soils, and have not undergone large changes in the N status. Forests of the Degradation Type lose nitrogen from the mineral soil (currently degradation is occurring on one site). Most forests that have moder or mor type humus and low‐soil pH values, and low N contents in the mineral soil have gone through the transient state of organic matter loss in the mineral soils. They accumulate organic matter in the forest floor (accumulation phase, currently 21 sites are accumulating 6–21 kg N ha^?1 yr^?1) or have reached a new (quasi‐) steady state with moder/mor type humus (n= 15). N retention in the accumulation phase has significantly increased in soil with N deposition (r²= 0.38), soil acidity (considering thickness of the forest floor as indices of soil acidity, r²= 0.43) and acid deposition (sulfate deposition, r²= 0.39). Retention of N (4–20 kg N ha^?1 yr^?1) by trees decreased and of soils increased with a decrease in the availability of base cations indicating the important role of trees for N retention in less acid soils and those of soils in more acid soils. Ecosystem theory could be successfully applied on the current data to understand the dynamics of N in temperate forest ecosystems.     

Changes in organic phosphorus composition in boreal forest humus soils: the role of iron and aluminium

Organic phosphorus (P) is an important component of boreal forest humus soils, and its concentration has been found to be closely related to the concentration of iron (Fe) and aluminium (Al). We used solution and solid state ³¹P NMR spectroscopy on humus soils to characterize organic P along two groundwater recharge and discharge gradients in Fennoscandian boreal forest, which are also P sorption gradients due to differences in aluminium (Al) and iron (Fe) concentration in the humus. The composition of organic P changed sharply along the gradients. Phosphate diesters and their degradation products, as well as polyphosphates, were proportionally more abundant in low Al and Fe sites, whereas phosphate monoesters such as myo-, scyllo- and unknown inositol phosphates dominated in high Al and Fe soils. The concentration of inositol phosphates, but not that of diesters, was positively related to Al and Fe concentration in the humus soil. Overall, in high Al and Fe sites the composition of organic P seemed to be closely associated with stabilization processes, whereas in low Al and Fe sites it more closely reflected inputs of organic P, given the dominance of diesters which are generally assumed to constitute the bulk of organic P inputs to the soil. These gradients encompass the broad variation in soil properties detected in the wider Fennoscandian boreal forest landscape, as such our findings provide insight into the factors controlling P biogeochemistry in the region but should be of relevance to boreal forests elsewhere.     

Humus status of different soils affected by pollution with fluorides from aluminum production in the Baikal region

The effect of pollution by fluorides from aluminum production on the humus status in different types of arable soils was studied in field experiments. They included modeling of a high pollution level by addition of NaF prevailing in industrial air emissions. The negative effect of fluorides on the humus status, related to an increase in the mobility of humic substances, was more pronounced in gray forest soil than in sod-meadow soil. This depended on the soil physicochemical properties determining the buffer capacity toward NaF and the content of water-soluble fluorides.