Development of actinomycetes in brown semidesert soil under low water pressure

Under laboratory conditions, the spores of a xerotolerant Streptomyces odorifera strain germinated in brown semidesert soil even at extremely low soil water pressure (P = ?96.4 MPa, ?964 atm, a _w 0.50); the plantlets increased in length and formed mycelium, on which a new generation of spores was produced (a complete development cycle of the actinomycetes??from a spore to the formation of new spores??passed). The duration of the first cycles of the actinomycetes?? development varied from 13 days at P = ?27 atm to 57 days at P = ?964 atm and was directly proportional to the absolute value of the soil water pressure (P). In the first cycles of the actinomycetes?? development, the rate of increase of the concentration of the germinated spores and mycelium, as well as the logarithms of the mycelium-to-germinated spore concentration ratios, was inversely proportional to the logarithm of P. These relationships indicated that the energy state of the water determined its availability to soil biota and, hence, the activity of its physiological and biochemical processes.     

Fixation of radiocaesium in an acid brown forest soil

The OAh and Ah horizons of acid brown and podzolic forest soils are reported to fix more radiocaesium than the mineral B horizons beneath them. We determined the respective influence of organic matter and clay minerals on the magnitude of Cs⁺ retention in a strongly acid brown forest soil in Belgium. The soil contained mica throughout the profile. Vermiculite was identified in the OAh and Ah horizons, and hydroxy interlayered vermiculite (HIV) in the Bw horizon. The OAh and Ah clay fraction retained much more Cs⁺ than the Bw horizon. The extraction of Al interlayers by Na-citrate resulted in a marked increase in Cs⁺ fixation in the Bw clays as well as the collapse of the vermiculitic layers after K⁺ saturation. Organic matter had a strong but indirect effect on Cs⁺ fixation. In the Bw horizon, acid weathering of layer silicates releases free Al and produces HIV minerals in which Al polymers block the access of radiocaesium onto Cs⁺-specific sites. In OAh and Ah horizons, free Al is complexed by organic acids. Consequently, the interlayer specific sites remain accessible for Cs⁺ fixation.     

烟台棕壤土饱和导水率的初步研究

该文利用单环入渗的概化解,对不同土地利用方式下烟台棕壤土的饱和导水率进行了研究,同时分析了不同单环直径对求解饱和导水率产生的影响。研究结果表明：草地、裸地和道路的入渗速率、累积入渗量和饱和导水率呈现依次降低的变化趋势,利用直径为20、30和45 cm的入渗环得到的饱和导水率具有明显的差异性。根据求解的饱和导水率计算的累积入渗量非常接近实测值,整体相对误差很小,草地、裸地和道路,在5、7和40 m in后浮动在5%以内;在15、43和55 m in后变化幅度小于1%。20、30和45 cm入渗环累积入渗量计算值的相对误差初始阶段波动较大,随后逐渐趋于平稳。     

Volcanic ash additions control soil carbon accumulation in brown forest soils in Japan

Abstract

The objective of the present study was to clarify the influence of volcanic ash addition on soil carbon stocks and the carbon accumulation process in brown forest soils (BFS) in Japan. The degree of volcanic ash addition to the soil was estimated according to the acid ammonium oxalate extractable aluminum (Al_ox) and lithic fragment contents, and their vertical distribution patterns. The BFS was classified in order of increasing volcanic ash influence on the soil into the following types: high Al_ox content with no gravel (H-Al_ox-NGv), high Al_ox with a high gravel content (H-Al_ox-Gv), moderate Al_ox (M-Al_ox), and low Al_ox (L-Al_ox), and then analyzed for carbon content, carbon amount, carbon stock, Al_ox amount and pyrophosphate extractable aluminum (Al_py) amount. The correlation between the carbon and Al_py amounts and the relationship between the Al_py and Al_ox amounts in the BFS samples indicated that the amount of carbon is determined by Al—humus complex formation, which is defined by the active Al generated from additional volcanic ash in BFS soil samples of BFS. Therefore, soils with thicker horizons and greater amounts of Al_ox had higher carbon levels in deeper horizons. For this reason, soil carbon stocks at depths of 0–30 cm and 0–100 cm, and in the effective soil depth of BFS, were larger and followed the order H-Al_ox-NGv = H-Al_ox-Gv > M-Al_ox > L-Al_ox. Furthermore, successive accumulations of volcanic ash on the soil surface promoted soil carbon accumulation as a result of the development of the surface horizon in H-Al_ox-NGv BFS. Our results suggest that volcanic ash additions control the soil carbon accumulation of forest soil in Japan.     

Microbial weathering of a brown forest soil: Influence of partial sterilization

Distilled water or nutrient medium with no addition (no sterilization), with thymol added (partial sterilization) or with Na merthiolate added (total sterilization) were semi-continuously perfused through 65 g soil columns. Amounts of Fe, Al, Mg solubilized throughout a 6 week period were respectively 15.2, 27.2, 21.0 mg (non-sterile columns); 55.7. 49.3, 45.7 mg (partially sterile columns): 0.4. 2.6, 11.0 mg (totally sterile columns). Partial sterilization also promoted microbial solubilization of Si. Mn. Ca and increased the weathering indices of Al and Fe. Partial sterilization decreased the total number of microorganisms and reduced the number of species. Fungi were eliminated (except for some yeasts). Moreover the metabolism of the resistant species was changed by this treatment. Thymol increased the yield of compounds such as oxalic acid. known to be active complexing agents.Ecological implications of the stimulation of microbial weathering through partial sterilization are discussed.     

Effects of incubation on forms of phosphorus added to an acid brown forest soil in Czechoslovakia

The effects of farmyard manure (FYM) and concentrated superphosphate (CSP) on the proportions of different fractions of inorganic P with the passage of time were studied through incubation of samples of an acid (pH 4.8, KCl) brown forest soil of Czechoslovakia.The application of FYM and CSP, either singly or in combination, resulted in appreciable increases in different forms of P over the controls. The amounts of P added to soil through FYM and CSP were recovered mainly in the (NH₄)₂SO₄-, CH₃COOH-, NH₄F- and NaOH-soluble fractions, whereas recovery in the H₂SO₄-soluble fraction was very small. The highest recovery of added P was in the (NH₄)₂SO₄-soluble fraction. The different fractions of P in the untreated as well as the incubated samples ranked in the order of NaOH-soluble P > (NH₄)₂SO₄-soluble P > NH₄F-soluble P > H₂SO₄-soluble P > CH₃COOH-soluble P, except after 15 and 45 days of incubation when CH₃COOH-soluble P was higher than the H₂SO₄-soluble fraction in samples that had received CSP and FYM+CSP. With prolongation of incubation time there was a decrease in (NH₄)₂SO₄-, CH₃COOH- and NH₄F-soluble P and a continuous increase in NaOH-soluble P, irrespective of treatments. The H₂SO₄-soluble P changed little during incubation. The use of FYM alone or with CSP resulted in a slower rate of decrease in the forms of P extracted with (NH₄)₂SO₄. Moreover, in the control the decrease in (NH₄)₂SO₄-, CH₃COOH- and NH₄F-soluble P and the consequent increase in the NaOH-soluble fraction were more pronounced after 90 and 180 days of incubation.     

Influence of repeated prescribed burning on the soil fungal community in an eastern Australian wet sclerophyll forest

A long-term prescribed burning experiment, incorporating replicated plots that receive burning biennially (2 yr burn) or quadrennially (4 yr burn) and unburned controls, has been maintained in a wet sclerophyll forest at Peachester, Queensland, Australia since 1972. In 2003 we extracted DNA from soil collected from the experimental plots and investigated the influence of the burning on the soil fungal community by comparing denaturing gradient gel electrophoresis (DGGE) profiles of PCR-amplified partial rDNA internal transcribed spacer regions (ITS1). Canonical analysis of principal coordinates (CAP) of the DGGE profiles of the upper 10 cm of the soil profile grouped the data strongly according to treatment, indicating that both burning regimes significantly altered fungal community structure compared to the unburned controls. In contrast, no obvious trend was observed for soil from a depth of 10-20 cm of the profile. Sequencing of selected DGGE bands found no obvious patterns of presence/absence of taxonomic groups between the treatments. Analysis of soil nitrogen and carbon by mass spectrometry indicated that total soil C and N, along with both gross and net N mineralisation, were significantly lower in 2 yr plots compared to control and 4 yr plots.     

Assessing the potential for forest effects due to soil acidification in Maryland

Calculations with the PROFILE model indicates that present acid deposition will lead to soil solution BC/Al molar ratios in the forest soils of Maryland far below the limits used for calculation of critical loads in Europe. Weathering rates and molar soil solution BC/Al ratios were calculated using measured mineralogy and texture. It has been assumed that the laboratory experiments on tree seedling response to soil solution Al concentration is applicable to field conditions as applied in the PROFILE model and that the observed connection between growth and needle loss for Sweden is also valid for North America. The assumptions were utilized to estimate the potential for forest damage due to soil acidification in Maryland. The results for Maryland was used to speculate over the possibilities for adverse effects due to soil acidity in Northeastern United States. A preliminary comparison with Maryland and European results, suggests that the threat of soil acidification to forest health in the Northeastern United States may have been underestimated.     

Consequences of forest conversion to pasture and fallow on soil microbial biomass and activity in the eastern Amazon

The main change in soil use in Amazonia is, after slash and burn deforestation followed by annual crops, the establishment of pastures. This conversion of forest to pasture induces changes in the carbon cycle, modifies soil organic matter content and quality and affects biological activity responsible for numerous biochemical and biological processes essential to ecosystem functioning. The aim of this study was to assess changes in microbial biomass and activity in fallow and pasture soils after forest clearing. The study was performed in smallholder settlements of eastern Brazilian Amazonia. Soil samples from depths of 0–2, 2–5 and 5–10 cm were gathered in native forest, fallow land 8–10 yr old and pastures with ages of 1–2, 5–7 and 10–12 yr. Once fallow began, soil microbial biomass and its activity showed little change. In contrast, conversion to pasture modified soil microbial functioning significantly. Microbial biomass and its basal respiration decreased markedly after pasture establishment and continued to decrease with pasture age. The increase in metabolic quotient in the first years of pasture indicated a disturbance in soil functioning. Our study confirms that microbial biomass is a sensitive indicator of soil disturbance caused by land‐use change.     

改变碳输入对南亚热带海岸沙地典型天然次生林土壤呼吸的影响

土壤呼吸是陆地生态系统碳循环的一个重要过程,开展环境因子和改变碳输入对土壤呼吸影响的研究具有重要意义.2015年3月-2016年2月,在南亚热带海岸沙地典型天然次生林中设置去除根系、去除凋落物、加倍凋落物和对照4种处理,采用LI-8100连续观测改变碳输入对土壤呼吸的影响.结果表明:改变碳输入没有显著影响l0cm土壤温度和湿度(P＞0.05);不同处理土壤呼吸速率存在明显的季节变化,表现为夏高冬低,最大值出现在5月或者6月,最小值出现在11月或12月;土壤呼吸速率的年均值为加倍凋落物＞对照＞去除根系＞去除凋落物,不同改变碳输入方式均降低了土壤呼吸的Q10值;矿质土壤呼吸、凋落物呼吸和根系呼吸对土壤总呼吸的贡献分别为41.24％、43.29％和15.45％;不同处理土壤呼吸速率分别与土壤温度和湿度呈显著的指数和线性正相关(P＜0.05),双因子模型能解释土壤呼吸变异的45％ ～ 69％;改变碳输入影响土壤可溶性有机碳和微生物生物量碳,不同处理土壤呼吸速率与可溶性有机碳和微生物生物量碳呈正相关.因此,改变碳输入引起土壤易变碳的变化进而影响土壤呼吸.     

Structural-functional specificity of the complexes of psychrotolerant soil actinomycetes

The active growth and development of psychrotolerant actinomycetes take place in peat and podzolic soils of the tundra and taiga at temperatures below 10°C. The population density of psychrotolerant mycelial prokaryotes in these soils reaches thousands and tens of thousands of CFU/g of soil, and the length of their mycelium is up to 380 m/g of soil. The application of fluorescent in situ hybridization (the FISH method) demonstrated that the metabolically active psychrotolerant representatives of the phylogenetic group of Actinobacteria comprise up to 30% of the total number of bacteria in prokaryotic microbial communities of oligotrophic peat bog and podzolic soils. The portion of metabolically active mycelial actinobacteria exceeds the portion of unicellular actinobacteria. Psychrotolerant streptomycetes isolated from peat bog soils possess pectinolytic, amylolytic, and antagonistic activities at low temperatures (5°C).     

Consistent effects of eastern subterranean termites (Reticulitermes flavipes) on properties of a temperate forest soil

Termites inhabit a large portion of land covered by temperate forests. Climate warming and urbanization will likely extend their range and increase their densities in these ecosystems but, compared to their tropical counterparts, little is known about their effects on soil properties and processes. If temperate termites have the strong ecosystem engineering effects of tropical termites, then knowledge of their ecology and impacts will be vital for predicting how temperate systems respond to environmental change. We investigated how feeding and tunneling by the eastern subterranean termite, Reticulitermes flavipes, affected wood decomposition and soil properties under decaying wood. Twelve laboratory microcosms filled with mineral soil and with wood blocks of four common temperate tree species, received R. flavipes soldiers and workers at field densities, with an additional five termite-free microcosms serving as controls. After 25 weeks, the effects of termites on wood mass loss, and on carbon and nitrogen dynamics, differed across tree species, yet their effects on soil properties were consistent regardless of wood type. Microbially-available carbon in soil was 20% higher with termites and soil moisture content 20% lower. Soil pH was more acid with termites and their effects on soil microbial biomass were positive but non-significant. These soil responses were consistent regardless of the wood species, suggesting that termite effects on soil are dictated largely by their activity within the soil matrix and not by their feeding rate on specific wood substrates. These results are among the first to quantify the effects of temperate forest termite activity on soil properties, demonstrating the potential for these termites to shape biogeochemical cycling and plant communities through their alteration of the soil environment.     

Adapting ecotoxicological tests based on earthworm behavior to assess the potential effectiveness of forest soil liming

Two laboratory experiments were carried out to determine the potential effects of lime application on the behavior of earthworms inoculated in an acidified forest soil from Vosges Mountains. Several field soils were studied: (i) a non-limed soil that had received decades of atmospheric acid depositions $({\text{pH}}_{{\text{H}}_2\text{O}}=3.9)$, (ii) an in situ limed soil that had been limed 6 years before at 2.5 t ha^?1 $({\text{pH}}_{{\text{H}}_2\text{O}}=4.2)$ and (iii) in vitro limed soils composed of non-limed soil mixed with several lime amounts in the laboratory corresponding to field rates of 1, 2.5, 5, 10 and 20 t ha^?1. Firstly, we adapted the earthworm avoidance test (ISO, 2006) by using Eisenia fetida as the model organism and Lumbricus castaneus, a local species, to determine earthworm preference between non-limed and limed soils. Secondly, a cast production (CP) study was performed according to Capowiez et al. (2009) with Lumbricus terrestris, in seven different treatments (non-limed soil, in situ limed and five in vitro limed soils with pH from 5 to 6.3). Both species avoided the non-limed soil in favour of in situ and in vitro limed soils for both species. Results of the CP bioassay showed that the bioturbation behavior of L. terrestris significantly increased with the increase of soil pH, following a dose–response curve. However, in the long term (>6 years), the application of lime was insufficient to significantly improve soil conditions for enhancing earthworm activity. In conclusion, we may recommend this kind of earthworm laboratory tests with field soils to assess any changes in soil quality over time due to liming application.     

华北落叶松人工林蒸腾特征及其与土壤水势的关系

 利用野外定位观测技术,于2008年5—10月在宁夏六盘山叠叠沟小流域对华北落叶松林整个生长季土壤水势的变化规律进行研究。结果显示:1)降雨量是影响土壤水势变化的主要因素,土壤水势在不同深度变化趋势基本一致,但变化幅度有较大差异,020、2040、4060cm土层的土壤水势梯度在6—9月份最大,8月份水势梯度最低;2)华北落叶松5—10月各月的耗水速率排序为6月>5月>7月>8月>9月>10月,耗水量分别占生长季的20.3%、25.4%、20.1%、18.6%、15.1%、10.7%,耗水月主要分布在6月;3)在华北落叶松生长季前期土壤水分短缺,生长后期水分充足,2个不同土壤水分条件的树干液流速率表现明显差异,充足条件下蒸腾耗水明显高于短缺条件,且水分亏缺时期20cm和60 cm土壤水势与树干液流变化相关性极显著。研究表明土壤水分亏缺与否是华北落叶松蒸腾耗水差异的主要原因,生长季中前期土壤水分对华北落叶松生长至关重要。     

Influence of forest disturbance on CO2, CH4 and N2O fluxes from larch forest soil in the permafrost taiga region of eastern Siberia

Abstract

To evaluate the effect of increasing forest disturbances on greenhouse gas budgets in a taiga forest in eastern Siberia, CO₂, CH₄ and N₂O fluxes from the soils were measured during the growing season in intact, burnt and clear-felled larch forests (4–5 years after the disturbance). Soil temperature and moisture were higher at the two disturbed sites than at the forest site. A 64–72% decrease in the Q ₁₀ value of soil CO₂ flux from the disturbed sites compared with the forest site (5.92) suggested a reduction in root respiration and a dominance of organic matter decomposition at the disturbed sites. However, the cumulative CO₂ emissions (May–August) were not significantly different among the sites (2.81–2.90 Mg C ha^?1 per 3 months). This might be because decreased larch root respiration was compensated for by increased organic matter decomposition resulting from an increase in the temperature and root respiration of invading vegetation at the disturbed sites. The CH₄ uptake (kg C ha^?1 per 4 months [May–September]) at the burnt site was significantly higher (–0.15) than the uptake at the forest (–0.045) and clear-felled sites (0.0027). Although there were no significant differences among the sites, N₂O emission (kg N ha^?1 per 4 months) was slightly lower at the burnt site (0.013) and higher at the clear-felled site (0.068) than at the forest site (0.038). This different influence of burning and tree felling on CH₄ and N₂O fluxes might result from changes in the physical and chemical properties of the soil with respect to forest fire.     

Effects of decreasing water potential on gross ammonification and nitrification in an acid coniferous forest soil

Changes in the soil water regime, predicted as a consequence of global climate change, might influence the N cycle in temperate forest soils. We investigated the effect of decreasing soil water potentials on gross ammonification and nitrification in different soil horizons of a Norway spruce forest and tested the hypotheses that i) gross rates are more sensitive to desiccation in the Oa and EA horizon as compared to the uppermost Oi/Oe horizon and ii) that gross nitrification is more sensitive than gross ammonification. Soil samples were adjusted by air drying to water potentials from about field capacity to around −1.0 MPa, a range that is often observed under field conditions at our site. Gross rates were measured using the ¹⁵N pool dilution technique. To ensure that the addition of solute label to dry soils and the local rewetting does not affect the results by re-mineralization or preferential consumption of ¹⁵N, we compared different extraction and incubation times.T₀ times ranging from 10 to 300 min and incubation times of 48 h and 72 h did not influence the rates of gross ammonification and nitrification. Even small changes of water potential decreased gross ammonification and nitrification in the O horizon. In the EA horizon, gross nitrification was below detection limit and the response of the generally low rates of gross ammonification to decreasing water potentials was minor. In the Oi/Oe horizon gross ammonification and nitrification decreased from 37.5 to 18.3 mg N kg⁻¹ soil d⁻¹ and from 15.4 to 5.6 mg N kg⁻¹ soil d⁻¹ when the water potential decreased from field capacity to −0.8 MPa. In the Oa horizon gross ammonification decreased from 7.4 to 4.0 mg N kg⁻¹ soil d⁻¹ when the water potential reached −0.6 MPa. At such water potential nitrification almost ceased, while in the Oi/Oe horizon nitrification continued at a rather high level. Hence, only in the Oa horizon nitrification was more sensitive to desiccation than ammonification. Extended drought periods that might result from climate change will cause a reduction in gross N turnover rates in forest soils even at moderate levels of soil desiccation.     

Influence of moisture on the vital activity of actinomycetes in a cultivated low-moor peat soil

It was found that the actinomycetal complex of a cultivated low-moor peat soil is characterized by a high population density and diversity of actinomycetes; representatives of eleven genera were isolated from this soil: Streptomyces, Micromonospora, Actinomadura, Saccharopolyspora, Microbispora, Microtetraspora, Streptosporangium, Nocardioides, Saccharomonospora, Kibdelosporangium, and Thermomonospora. Some genera were isolated from the soil under all the studied levels of soil moisture. The so-called rare (rarely occurring) genera (Saccharomonospora, Kibdelosporangium, and Thermomonospora) were isolated upon the low level of soil moisture, which ensured an absence of competition from the more abundant actinomycetes. Spores of all the studied actinomycetes could germinate under the low moisture level (a _w = 0.67). The level of moisture a _w = 0.98 was found to be optimal for the development of the actinomycetes. The complete cycle of the development of all the actinomycetes up to spore formation occurring was only observed under the high moisture level (a _w = 0.98).     

Effect of heptachlor on numbers of bacteria,actinomycetes and fungi in soil

Growth of many soil microorganisms was inhibited on culture media containing heptachlor. At a concentration of 25 mg/l., heptachlor killed 63 per cent of the bacteria transferred from soil dilution plates. Heptachlor, at 100 mg/1. in agar media used for isolating microorganisms from soil, prevented the development of 89 per cent of the bacteria, 81 per cent of the actinomycetes, and 50 per cent of the fungi that appeared on isolation plates without heptachlor. After heptachlor was added to soil, fungal populations declined and bacterial populations increased. Numbers of bacteria were related to amount of heptachlor added; higher concentrations of heptachlor in soil resulted in larger populations. A selective increase in numbers of fungi which would grow on media containing heptachlor at 100 mg/l. occurred in soils amended with heptachlor in amounts ordinarily used in field practices, but a similar increase of heptachlor-resistant bacteria occurred only in soils amended with higher amounts of heptachlor.     

Influence of sea salts on the soil metabolism

Abstract

Microbial metabolism in reduction process of waterlogged paddy soils has been studied by Takai, Koyama, and Kamura (1, 2, 3, 4, 5, 6), Koyama (7, 8, 9, 10, 11, 12), and others. The results indicated that microbial metabolism in waterlogged soils takes place according to the following steps: (1) In the early stage of the incubation period, dissolved O₂, is consumed and the redox potential drops rapidly. (2) NO₂? and NO₂? are reduced to N₂. (3) Mn⁴⁺ is reduced to Mn²⁺. (4) Fe³⁺ is reduced to Fe²⁺. (5) SO₄ ²? is reduced to S^2?. (6) H₂ and CH₄ are produced. Takai and Chiang (13) reported that NH₄₊ and PO₄ ³⁺ in waterlogged paddy soils increase with the incubation period. Chiang and Takai (14) indicated that carbohydrates in the soil solutions almost remain constant throughout the incubation period, however, organic acids change similarly to those reported previously (5, 6).