Forest Soil Ecology

Structural information on soil organic matter (SOM) at the molecular level can be obtained on diverse structural units that are amenable to degradation techniques. Chemolytic techniques in combination with colorimetric analyses or GC MS are used to determine amino acids (proteins), sugars (polysaccharides), lipids, or aromatic oxidation products from lignin or charred organic matter. Microbial markers (amino sugars, muramic acid) are analyzed after hydrolysis and gas chromatographic separation. Macromolecular structures can also be subjected to thermochemolytic degradation or pyrolysis and subsequent analysis of the fragments by GC MS. Alternative techniques for the examination of organic matter in heterogeneous macromolecular mixtures are non-destructive spectroscopic methods, such as nuclear magnetic resonance (NMR) spectroscopy. Although this technique can give good results concerning the gross chemical composition, speci®c compounds are hardly identi®ed. The combination of spectroscopic techniques with thermolytic and chemolytic methods will add substantially to the understanding of the nature of refractory soil organic matter. Physical fractionation prior to analysis provides a means to dierentiate between distinct SOM pools that can be further characterized by the methods described above. Studies on SOM structural characteristics have focused mainly on the A horizons of soils under agriculture and litter biodegradation in forest soils and need to be extended to a wider variety of soil types and the subsoil. #

and total counts) correlated negatively. The overall assessment of soil activity, the soil respiration, did not correlate with either. Significant correlations were found between the principal components of pH, CLPP, EAA, and culturable and total number of bacteria, while no correlations were found to soil respiration, loss on ignition and soil moisture content. The pH in the test system might make differences between bacterial communities more detectable. The functional characterization of the bacterial communities by the growth based CLPP correlated positively to the bacterial community function assayed by the EAA, which is independent of growth and, hence, more closely reflects the in situ activities.

Invasion of exotic forest pests and pathogens is a serious environmental problem for many forests throughout the world, and has been especially damaging to forests of eastern North America. We studied the impacts of an exotic pest/pathogen complex, the beech bark disease (BBD), in the Catskill Mountains of New York State, USA. In this region, BBD has caused a decline in the basal area of American beech (Fagus grandifolia Ehrh.) over the last 60 years and this decline has been accompanied by an increase in the basal area of sugar maple (Acer saccharum Marsh.). We studied the impacts of the BBD on carbon (C) and nitrogen (N) cycling using a series of stands that represented a sequence of disease impact and beech replacement by sugar maple. Our study showed that these longterm changes in tree species composition can lead to important changes in C and N cycling in the ecosystem, including an increase in litter decomposition, a decrease in soil C:N ratio, and an increase in extractable nitrate in the soil and nitrate in soil solution. Rates of potential net N mineralization and nitrification did not change across the BBD sequence, but the fraction of mineralized N that was nitrified increased significantly. Many of the observed changes in ecosystem function are larger in magnitude than those attributed to climate change or air pollution, suggesting that the impacts of invasive pests and pathogens on tree species composition could be one of the most important factors driving changes in C and N cycling in these forests in the coming decades.

Positive effects of legumes and actinorhizal plants on N-poor soils have been observed in many studies but few have been done at high latitudes, which was the location of our study. We measured N 2 fixation and several indices of soil N at a site near the Arctic Circle in northern Sweden. More than 20 years ago lupine (Lupinus nootkatensis Donn) and gray alder (Alnus incana L. Moench) were planted on this degraded forest site. We measured total soil N, net N mineralization and nitrification with a buried bag technique, and fluxes of NH + 4 and NO − 3 as collected on ion exchange membranes. We also estimated N 2 fixation activity of the N 2 -fixing plants by the natural abundance of 15 N of leaves with Betula pendula Roth. as reference species. Foliar nitrogen in the N 2 -fixing plants was almost totally derived from N 2 fixation. Plots containing N 2 -fixing species generally had significantly higher soil N and N availability than a control plot without N 2 -fixing plants. Taken together, all measurements indicated that N 2 -fixing plants can be used to effectively improve soil fertility at high latitudes in northern Sweden.

Status of organic carbon (C), total nitrogen (N), available potassium (K), calcium (Ca) and phosphorus (P) in three different depths (0−5 cm, 5−15 cm and 15−30 cm) on two hill slopes of 35% and 55% in orange orchard cultivated by the Mro tribe of Chittagong Hill Tracts (CHTs) were evaluated and compared with those in degraded bush forests, through digging three profiles in each land use. The content of all the five nutrients was found to be higher in the soil of orange orchard than in the soil of forest. But the variation was not consistent for both the slopes. The content varied depth wise also, having the highest value in surface soil in case of both the land uses on both the slopes. A mean available K content was significantly higher in orange orchard than in forest on 55% slope, while it was lower on 35% slope. Surface soil contained the nutrients of K and Ca with the amount of 0.2905-mg·g -1 soil and 3.025-mg·g -1 soil respectively in the orchard, while 0.1934-mg·g -1 soil and ...

Seasonal fluctuations in the methane fluxes in the soil-atmosphere system were determined for gray forest soils of Central Russia. Consumption of atmospheric methane was found to exceed methane emission in gray forest soils under forest and in the agrocenosis. The average annual rates of atmospheric methane consumption by the soil under forest and in the agrocenosis were 0.026 and 0.008 mg C-CH 4 /(m 2 h), respectively. The annual rate of atmospheric methane oxidation in the gray forest soils of Moscow oblast was estimated to be 0.68 kton. Seasonal fluctuations in the methane oxidation activity were due to changes in the hydrothermal conditions and in the reserves of readily decomposable organic matter and mineral nitrogen, as well as to changes in the activity of methane oxidizers.

With regard to the high mortality of silver fir (Abies alba Mill.) in Italy, pathological and climatic causes are considered crucial, while soil properties are usually neglected. Two of the largest Tuscan forests of this species, the one of Vallombrosa and the other of Mount Amiata, are seriously affected byHeter obasidion annosum, a fungus causing root rot. However, in spite of the same provenance of firs and intersterile group of the fungus, the tree death is different at the two sites. In one case, firs quickly died standing, while in the other they were uprooted after a slow course of the illness. A study was conducted on the two localities to perceive the role of soil properties in this connection. In the light of our results, pedological conditions are important, negatively affecting the plants either “directly” — limiting deep rooting and preventing the trees to achieve sufficient anchorage in the ground — and “indirectly” — favouring the spread and the virulence ofH. annosum. Mit Blick auf die hohe Sterblichkeit der Weiß-Tanne (Abies alba Mill.) in Italien werden pathologische und klimatische Gründe als entscheidend betrachtet, Bodeneigenschaften jedoch gewöhnlich vernachlässigt. Zwei der ausgedehntesten toskanischen Wälder dieser Gattung, der eine in Vallombrosa, der andere am Amiata-Berg, sind schwer vonHeterobasidion annosum betroffen, einem Pilz, der Wurzelfäulnis auslöst. Trotz derselben Herkunft der Tannen und der intersterilen Gruppe des verläuft der Baumtod an beiden Standorten verschieden. Im einen Fall starben die Tannen rasch und blieben stehen, während sie im anderen Fall nach langsamem Krankheitsverlauf entwurzelt wurden. An beiden Standorten wurde eine Studie durchgeführt, um in diesem Zusammenhang die Rolle der Bodenbeschaffenheit herauszufinden. In Anbetracht unserer Ergebnisse sind pädologische (pedological) Bedingungen wichtig und beeinträchtigen die Pflanzen sowohl „direkt“ — indem sie tiefe Verwurzelung einschränken und die Bäume am Erreichen ausreichender Bodenverankerung hindern — als auch „indirekt“ — indem sie Ausbreitung und Virulenz vonH. annosum begünstigen.

Plant growth depends upon the activity of numerous types of organisms within the environment. The recycling of nutrients in the forest floor involves the interaction of a vast diversity of bacteria, fungi, protozoa, and invertebrates. Arthropods are integral to the initial shredding of the litter, which exposes nutrients to microbial digestion. Hundreds of California species either feed directly upon decomposer microorganisms or prey upon microbivorous taxa. Microbivory enhances the succession of microbial taxa with different enzymatic capabilities for processing soil resources. The final step of recycling, the entry of soil nutrients back into a root, is largely the result of invertebrates feeding upon microbes which have immobilized nutrients within the rhizosphere. Forest management practices can significantly alter soil foodwebs, which may in turn have significant effects on long-term soil productivity. Because arthropods facilitate a number of different soil processes, assays of soil arthropod abundance and community composition may prove to be useful in developing an understanding of the effects of forest management on nutrient cycles in forest soils.

Few studies have been done to evaluate the transfer of catabolic plasmids from an introduced donor strain to indigenous microbial populations as a means to remediate contaminated soils. In this work we determined the effect of the conjugative transfer of two 2,4-D degradative plasmids to indigenous soil bacterial populations on the rate of 2,4-D degradation in soil. We also assessed the influence of the presence of 2,4-D on the number of transconjugants formed. The two plasmids used, pEMT1k and pEMT3k, encode 2,4-D degradative genes (tfd) that differ in DNA sequence as well as gene organisation, and confer different growth rates to Ralstonia eutropha JMP228 when grown with 2,4-D as a sole carbon source. In an agricultural soil (Ardoyen) treated with 2,4-D (100 ppm) there were ca. 10(7) CFU of transconjugants per gram bearing pEMT1k as well as a high number of pEMT3k bearing transconjugants (ca 10(6) CFU/g). In this soil the formation of a high number of 2,4-D degrading transconjugan...

Carbon storage in aboveground tree biomass and soil organic matter (in depth of A layer development i.e., up to 20 cm) was studied in 22-32 year-old post-mining sites in the northwest of the Czech Republic. Four replicated sites afforested with different tree species (spruce, pine, larch, oak, lime or alder) were compared with sites left to natural regeneration which were dominated by aspen, birch and willow. No topsoil was applied at the sites; hence carbon accumulation resulted from in situ soil development on alkaline tertiary clays that were dumped on the heaps. In aboveground tree biomass, carbon storage ranged from 17.0 ± 5.9 (mean ± SEM) to 67.6 ± 5.9 t ha -1 and the rate of C accumulation increased from 0.60 ± 0.09 to 2.31 ± 0.23 t ha -1year -1 (natural regeneration \ pine \ spruce \ oak \ lime \ alder \ larch). Carbon storage in soil organic matter varied from 4.5 ± 3.7 to 38.0 ± 7.1 t ha -1 and the rate of C accumulation in soil organic matter increased from 0.15 ± 0.05 to 1.28 ± 0.34 t ha -1 year -1 at sites in the order: natural regeneration \ spruce \ pine, oak \ larch \ alder \ lime. Carbon storage in the soil was positively correlated with aboveground tree biomass. Soil carbon was equivalent to 98.1% of the carbon found in aboveground tree biomass at lime dominated sites, but only 21.8% at sites with natural regeneration. No significant correlation was found between C storage in soil and aboveground litter input. Total soil carbon storage was correlated positively and significantly with earthworm density, and occurrence of earthworm cast in topsoil, which indicated that bioturbation could play an important role in soil carbon storage. Hence, not only restoring of wood production, but also restoring of soil community is critical for C storage in soil and whole ecosystem.

The long-term storage of soil organic matter (SOM) in forest soils is still poorly understood. In this study, particle size fractionation in combination with accelerator mass spectroscopy (AMS) and solid state 13 C nuclear magnetic resonance (NMR) spectroscopy was applied to investigate organic carbon (OC) stabilisation in Cambisol and Luvisol profiles under spruce (Picea abies) and beech (Fagus sylvatica L.) forests. In most samples, OC was preferentially associated with o2 mm fractions. Throughout soil profiles the contribution of OC in the clay fraction to the total OC increased from 27%-53% in A horizons to 44-86% in E, B and EB horizons. The 200-2000 mm fractions from all sites and all depths showed a percentage of modern C (pmC)4100. They were enriched in 14 C owing to high inputs of recent material from leaves and roots. Clearly less active material was associated with o2 and 2-20 mm fractions. This demonstrated that the particle size fractionation procedure applied to our study was capable to isolate a young OC fraction in all samples. The pmC values were strongly decreasing with depth but the decrease was much more pronounced in the fine fractions. The o2 and 2-20 mm fractions of B, E and EB horizons revealed radiocarbon ages between 512 and 4745 years before present which indicated that the SOM in those horizons was little affected by the recent vegetation. The major components of labile and stable SOM pools in topsoils and subsoils were always O/N-alkyl C (28-53%) and alkyl C (14-48%) compounds. NMR spectra of bulk soils and particle size fractions indicated that high alkyl C and O/N-alkyl C proportions throughout the soil profile are typical of Cambisols and Luvisols which were not subjected to regular burning. A relation between radiocarbon age and chemical composition throughout soil profiles was not observed. This suggests that the long-term stabilisation of SOM is mainly controlled by the existence of various mechanisms of protection offered by the soil matrix and soil minerals but not by the chemical structure of SOM itself. r

Hypericum perforatum is used as a folk remedy for the treatment of various neurological disorders. In this study, antioxidant activity of flower-bearing branches of H. perforatum was investigated employing various in vitro assay systems. IC 50 for DPPH radical-scavenging activity was 96.0 ± 3.7 ȝg ml -1 . Extract showed potent nitric oxide scavenging activity between 6.25 and 100 ȝg ml -1 . Percentage of inhibition was increased with increasing concentrations of the extract. IC 50 was 21.1±1.8 ȝg ml -1 . Extract showed good reducing power that was comparable with vitamin C (p> 0.05). Extract showed very weak Fe 2+ chelating ability. Percentage of inhibition was 41% at 200 ȝg ml -1 in scavenging of H 2 O 2 . This plant was a good source of phenols and contains very high amount of total phenolics. Total phenol compounds, as determined by the Folin Ciocalteu method, was 505.7 ± 18 mg GAE and the total flavonoid content, by AlCl 3 method was 23.8 ± 1.6 mg QE. Antioxidant activity may be attributed, at least in part, to the presence of high amount of phenols and flavonoids in the extract. Potent nitric oxide scavenging activity may explain reported anti-inflammatory and CNS activities of this plant. These activities may be partially mediated by NO pathway.

The upper part of the Moselle river basin, northeastern France, shows contrasting lithology and topography: granitic formations upstream in the Vosges mountains and carbonate platform downstream on the Lorraine plateau. We measured concentration and isotopic composition of dissolved SO 4 in the Moselle river and its main tributaries in order to identify the sources of sulfate. Rainwater, lichens, S-fertilizers and natural gypsum were also analyzed as potential sulfate sources. Along the Moselle river, dissolved SO 4 concentrations and S-O isotopes display relationships which suggest two major sources of sulfates: 1) a low concentration and low delta values (δ 34 S of 6-9‰ and δ 18 O of 6-9‰) component upstream and 2) a high concentration and high delta values (δ 34 S of up to 17‰ and δ 18 O of up to 13‰). These are likely 1) atmospheric S input with some retention time in forest soils as carbon-bonded sulfur and 2) sulfates from the dissolution of evaporites from the Muschelkalk and Keuper formations of the Lorraine plateau.

Forest conversion to coffee-based agroforestry leads to sudden disappearance of the litter layer and a decrease in the rate of litter fall, reducing food for ecosystem engineers such as earthworms. With time, however, a new litter layer is created potentially returning to forest-like conditions at the soil surface. This research quantified litter thickness, earthworm populations and soil macroporosity in response to land use change in the Sumberjaya benchmark area (West Lampung, Indonesia) by comparing: (a) remnant forest (control); (b) multistrata shaded coffee with fruit and timber trees, as well as nitrogen-fixing shade trees; (c) shaded coffee (nitrogen-fixing shade trees, but less than five tree species per plot); and (d) sun coffee ('monoculture') with coffee forming more than 80% of total stem basal area. Plots were selected with tree ages of 7-10 years in three slope classes: (a) flat (0-108); (b) medium (10-308); and (c) steep (>308). The mean standing necromass was 6.1, 4.5, 3.8 and 3.0 Mg ha À1 for forest, multistrata, shade coffee and sun coffee, respectively, without significant influences of slope. Fine, partly decomposed litter was 33-40% of total necromass, coarse leaf litter 14-16%, and twigs and branches comprised the remaining 43-52%. Soil organic carbon content (C org ) was highest in the forest. The largest annual litter input was found in the remnant forest (14 Mg ha À1 year À1 ), followed by multistrata, shaded and monoculture coffee systems, i.e., 9.8, 6.6 and 4.0 Mg ha À1 year À1 , respectively. The population density of earthworms in the forest was 50% lower than in multistrata coffee gardens (150 individuals m À2 ), but its biomass (31 g m À2 ) was twice that in the multistrata coffee gardens. The lowest population density of earthworms was found in the shade coffee system (150 individuals m À2 ) with a biomass of 7 g m À2 . A simple model suggests that the standing litter in the various land use systems is consistent with measured litter inputs and decay rates, but that the soil organic matter (SOM) content and macroporosity of the shade and multistrata systems are less than predicted. The recovery of a surface litter layer in sun coffee systems can provide protection from erosion with time, but will not be sufficient to restore macroporosity at the level of forest soils, leading to hydrologic alterations that favor overland flow. #

The content of labile, especially water extractable organic carbon (WEOC) is a sensible indicator of soil organic matter quality. The main objectives of this study were: i) to investigate the proile changes of cold and hot water extractable organic carbon in forest and arable soils; ii) to evaluate the correlation between these labile fractions of soil organic matter and total organic carbon content. The experiments were carried out on a Gleyic Albeluvisol (ABg) in the upper part of Dniester basin, Western Ukraine. The soil samples were taken from 50-cm depth soil
proile with 5-cm step. Total organic carbon (TOC), cold water extractable organic carbon (CWEOC) and hot-water extractable organic carbon (HWEOC) contents in soil were determined as well as pH (H2O) and electrical conductivity of soil:water suspensions. The results of this study showed that in 0–50 cm layer of arable soil TOC content decreased by 32%, CWEOC – by 23% and HWEOC – by 74% compared to forest soil that conirmed a
high informative role of HWEOC fraction. The proile changes of WEOC percentage were analysed. They also show that HWEOC is much more informative indicator of soil organic matter quality than CWEOC. The most prominent changes of soil chemical properties, TOC, CWEOC and HWEOC contents in response to deforestation
were observed in the top 5-cm soil layer. We suggested this thin soil layer to be deined as soil stress-sensitive zone.
Key  words:  dissolved  organic  carbon,  labile  fraction,  soil  organic  matter,  total  organic  carbon,  water-soluble organic matter.

The toxicities of two heavy metals, copper (Cu2+) and chromium (Cr6+), to barley (Hordeum vulgare L.) were evaluated using two types of substrates: artificial and natural forest soils. Phytotoxicity was assessed using a standardized toxicity test. Endpoints included plant emergence and shoot and root growth. Shoot and root concentrations of Cu and Cr were also measured. Data indicated that the root biomass was the most sensitive endpoint. The results showed that toxicity of Cr to root growth (IC50=6.6 μg/g in artificial soil; IC50=61.8 μg/g in forest soil) was higher than that of Cu (IC50=13.7 μg/g in artificial soil; IC50>322 μg/g in forest soil). Data also indicated that the toxicity of Cu and Cr was significantly decreased in the spiked forest soil, suggesting lower metal bioavailability to barley in the natural soil. Analysis of tissue concentrations in barley showed that Cu and Cr were mainly accumulated in the roots. Toxicity was correlated with Cr residues in shoots (⩽11.2 μg Cr/g and ⩽5.3 μg Cr/g for artificial and natural soils, respectively) and roots (⩽161 μg Cr/g and ⩽51.7 μg Cr/g for artificial and natural soils, respectively) and Cu residues in roots (⩽61.8 μg Cu/g and ⩽91.3 μg Cu/g for artificial and natural soils, respectively). Cu concentration in shoot tissues was ⩽61.8 μg Cu/g. Since it may overestimate toxicity, effect and risk assessment using spiked soils, particularly in artificial soil, must be used with diligence.

Exotic pests and pathogens can cause extensive mortality of native species resulting in cascading effects within an ecosystem. As ecosystems lose species to exotic enemies, ecosystem function may be disrupted if the ecological roles are not filled by the remaining species. To illustrate this concept, this paper examines the impacts of an exotic fungus (Discula dectructiva) on flowering dogwood (Cornus florida), historically a common understory tree species in eastern U.S. hardwood forests. Recent studies indicate that dogwood plays an important role in the health and ecological integrity of forest ecosystems throughout the eastern U.S. by increasing the availability of calcium in the biota-rich surface horizons of forest soils. However, Discula destructiva causes a disease, dogwood anthracnose, which can rapidly kill dogwood trees. This paper also illustrates how past fire has increased dogwood density and improved tree health in areas infected with anthracnose, suggesting that prescribed fire may offer a tool for land managers to maintain dogwood as a component in eastern U.S. hardwood forests by shifting the ''ideal'' disturbance regime of this previously fire-intolerant species.

The HEN value (=extractable part of microbial biomass N after fumigation) of the fumigation-extraction method was assessed using the C-to-N ratio of the organic matter which was rendered extractable by CHCln fumigation. The data for this calibration approach was obtained from 51 arable and 23 grassland soils. The second calibration approach was to compare the relationship between N rendered extractable by CHCl, fumigation and the C-to-N ratio measured in the flush of the fumigation--incubation method by recalculating data obtained from the literature. On the basis of these two approaches, we recommend using a /CEN value of 0.54 as originally proposed by Brookes et al. (Soil Biology & Biochemistry 17, 837-842, 1985).

Organic carbon levels of 542 soil samples from temperate lowland forest were determined by the original and modified Walkley-Black (WB) dichromate methods and total organic carbon (TOC) analysis. The performance and the lower and upper quantification limits of the WB method were assessed. Variable recovery rates were related to laboratory and field conditions and to the sample composition. The percentage carbon recovered by the original WB method was found to be systematically lower than commonly accepted, and the correction factor was estimated at 1.58 instead of 1.30-1.35. However, a good linear relationship with TOC enabled acceptable prediction of soil organic carbon which was most precise when using the original WB method. Texture class and pedogenetic horizon showed significant differences in recovery. Depending on the modifications of the WB method, recoveries varied significantly between laboratories, explaining up to 29% of the total variation of the topsoil carbon assessment of a site. Low recovery from samples was partly attributed to charcoal and resistant elementary carbon particles. No interference was found to be caused by iron or manganese compounds. In order to use WB carbon data of forest soils, laboratory-and method-specific determination of the recovery rate using a total analyser is strongly recommended. The original WB method was unable to predict reliably forest soil carbon contents higher than 8% TOC.

Agroforestry, the purposeful growing of trees and crops in interacting combinations, began to attain prominence in the late 1970s, when the international scientific community embraced its potentials in the tropics and recognized it as a practice in search of science. During the 1990s, the relevance of agroforestry for solving problems related to deterioration of family farms, increased soil erosion, surface and ground water pollution, and decreased biodiversity was recognized in the industrialized nations too. Thus, agroforestry is now receiving increasing attention as a sustainable land-management option the world over because of its ecological, economic, and social attributes. Consequently, the knowledge-base of agroforestry is being expanded at a rapid rate as illustrated by the increasing number and quality of scientific publications of various forms on different aspects of agroforestry.

Problem soils are those which owing to land or soil characteristics cannot be economically used for cultivation of crops without adopting proper management strategies. More than 50 per cent of 143 m ha-1 (net cultivated area) falls in the category of problems soils. More than 90 per cent of the land in the north eastern states alone is affected by soil acidity of varying degrees which have restricted the crop choice in more than 70 per cent of gross cropped area in this region to cereals particularly the rice. The amelioration of 25 million hectares promises additional 25 million tones of food grains. Besides, the fertilizer use as well its efficiency is also poor due to unfavorable pH conditions. The soil degradation due to salinity and alkalinity problems had affected significant chunk of fertile tracts, covering an area of about 67.27 lac hectares. The emphasis should therefore be given to solve these soil problems by adopting different management strategies like addition of different amendments, choice of crop, irrigation and drainage management for increasing the production as well as productivity on sustainable basis.

Physically-and biochemically-distinct fractions of soil organic matter (SOM) can be separated by density to yield: (i) low-density plant detritus fraction easily separable from soil minerals (f-LF), (ii) low-density materials strongly associated with minerals (m-LF), and (iii) high-density fraction (HF) rich in microbiallyprocessed organic matter strongly associated with minerals. The factors controlling the pool size and chemistry in these fractions, especially those in m-LF, are unclear. We examined the influence of climate and parent material on SOM in these fractions using two sets of forest soils (0-10 cm mineral horizon) developed from contrasting parent materials (metasedimentary vs. ultrabasic igneous rock) along an altitudinal gradient in Mt. Kinabalu, Borneo. From 700 m to upper altitudes (1700, 2700 m), where mean annual temperature decreases from 24 to 12°C with roughly constant rainfall, surface soil C stocks on both parent materials increased from 2.6-2.8 to 5.4-7.5 kg m − 2 with progressively greater proportions in m-LF and, to less extent, fresher plant detritus fractions. In HF, C and N concentrations increased with altitude though their stocks were roughly constant due to progressively lower bulk density. Labile C assessed by laboratory incubation of bulk soils correlated better with C concentrations in the two LF pools than in HF, especially at the lowest altitude where most SOM is strongly associated with minerals as HF. These results suggest that LF pools are more labile and more sensitive to altitude-induced, climate differences as compared to the HF pool that is protected by the mineral matrix. The C:N ratios of HF on metasedimentary rock increased with altitude (11 to 17) while those on ultrabasic rock remained essentially constant (14-15), implying interactive influence of altitude and parent material on stoichiometry. Unusually high C:N and alkyl-C in m-LF were found in mid-altitude soils, suggesting selective preservation of inherently recalcitrant materials in addition to, or instead of, mineral coating or aggregate occlusion of partially-degraded LF by microbial metabolites.

The aim of the present work was to provide a synopsis of the scientific literature concerning the effects of different tree species on soil and to quantify the effect of common European temperate forest species on soil fertility. The scientific literature dealing with the tree species effect on soil has been reviewed. The composition of forest overstory has an impact on the chemical, physical and biological characteristics of soil. This impact was highest in the topsoil. Different tree species had significantly different effects on water balance and microclimate. The physical characteristics of soils also were modified depending on the overstory species, probably through modifications of the soil fauna. The rates of organic matter mineralization and nitrification seem to be dependent on tree species. A coniferous species, Picea abies, had negative input-output budgets for some nutrients, such as Ca and Mg. This species promoted a higher soil acidification and a decrease in pH. Thus, it should not be planted in very poor soils in areas affected by acidic atmospheric depositions. Nevertheless, the effect of the canopy species on soil fertility was rarely significant enough to promote forest decline. The impact of a tree species on soil fertility varied depending on the type of bedrock, climate and forest management.

Soil fungi were isolated from different soil types of Jalgaon district. Out of them two forest soils, Pal and Manudevi forests were selected for the studies. Total 53 and 52 species belonging to 21 and 24 genera of fungi were isolated from these soils respectively. Deuteromycotina members were dominant. Aspergillus was the dominant genus from both these soils. Each forest soil has unique mycoflora. Some of the species showed remarkable seasonal distribution from these soils. Maximum number of fungi were isolated from Pal forest soils during winter season, while maximum species were isolated from Manudevi forest soils during rainy season.

A phosphate-solubilizing bacterial strain NII-0909 isolated from the Western ghat forest soil in India was identified as Micrococcus sp on the basis of phenotypic characteristics, carbon source utilization pattern, fatty acid methyl esters analysis, and 16S rRNA gene sequence. The strain exhibited the plant growthpromoting attributes of phosphate solubilization, auxin production, 1-aminocyclopropane-1-carboxylate deaminase activity, and siderophore production. It was able to solubilize (122.4 mg of Ca 3 PO 4 ml À1 ), and produce IAA (109 mg ml À1 ) at 30 C. P-solubilizing activity of the strain NII-0909 was associated with the release of organic acids and a drop in the pH of the NBRIP medium. HPLC analysis detected two organic acids in the course of P-solubilization. A significant increase in the growth of cow pea was recorded for inoculations under controlled conditions. Scanning electron microscopic study revealed the root colonization of strain on cow pea seedlings. These results demonstrate that isolates NII-0909 has the promising PGPR attributes to be develop as a biofertilizer to enhance soil fertility and promote the plant growth.

A study was conducted to evaluate the status of soil nutrients under E. grandis plantation in comparison with that in its adjacent submontane rain forest. Twenty sequare plots, with an area of 20 m×20 m for each, were established in both of E.grandis plantation and its adjacent sub-montane rain forest, independently. Soil samples were collected from each square plot, at five points (at the four corners and at the center) of each plot. The collected soil samples were mixed to make a composite and representative sample for each plot, independently. The analyses were done in a soil laboratory following appropriate methods. The analysis result indicated that there were no significance differences between E. grandis plantation and its adjacent sub-montane rain forest in the level of major soil nutrients (total N, available P, exchangeable K, Ca and Mg), pH and total carbon of soils (p < 0.05). There were significance differences between two sites of forest soils in percentage of clay particles, and exchangeable Na content. E. grandis plantation was found improving soil nutrients and total carbon as compared with that of its adjacent submontane rain forest.

Understanding native communities is a crucial step for the management of biological nitrogen fixation, since they may be either a source of efficient strains or a limiting factor when efficient strains need to be introduced. This work aimed to evaluate the density, diversity and efficiency of Leguminosae nodulating bacterial (LNB) communities and their component strains in soils under various land use systems (LUSs): pristine forest, agriculture, pasture, agroforestry, young secondary forest, and old secondary forest,. The LNB communities were trapped from these soils by using the promiscuous host siratro under controlled conditions. We also studied their relationships with physical and chemical attributes of the soil. Agroforestry and agriculture soil samples induced the highest number of nodules in siratro, while forest soil samples induced the lowest number of nodules. No relationship was found between LNB and Leguminosae species diversity in the LUSs. The soil chemical variables that were most related to differences in nodule number and shoot dry matter weight of plants inoculated with soil suspensions of the LUSs were, respectively: Ca 2+ , Mg 2+ , base saturation, exchangeable bases and Cu 2+ ; and pH, cation exchange capacity, B, Cu 2+ and clay. Although, LNB communities from all LUSs were efficient under controlled and similar conditions, they were found to be composed of strains with variable efficiency: inefficient, efficient, highly efficient and superior efficiency. Efficient strains occurred at the highest frequency in all LUSs. The isolated strains presented similar and new sequences that were phylogenetically related to well known LNB genera in α-and β-Proteobacteria. Unusual genera in these branches, as well as in other branches, which are probably endophytic bacteria, were also isolated from nodules. These data support siratro as a useful trap species to study the LNB biodiversity of diverse ecosystems in tropical soils. The fact that the highest diversity and nodulation were seen in managed systems such as agriculture and agroforestry suggests a high resilience of LNB communities to changes in land use after deforestation in a region where large forest areas are still preserved and can be a source of propagules.

Pyrocatechol violet and thiocyanate methods used in the water analysis for spectrophotometric determination of aluminum (Al) and iron (Fe), respectively, were modified for the determination of these elements in different types of commonly used extracts of soils and sediments. The extracts were digested with nitric and perchloric acid in an Al-heating block as for the total phosphorus (P) analysis and aliquots of the digests were analyzed for Al and Fe. Comparison of the spectrophotometric methods with inductively coupled plasma method was demonstrated using (I) oxalate, citrate-dithionite, and pyrophosphate extracts of 25 samples of acid forest soils, and (ii) water, sodium hydroxide, dithionitebicarbonate, and hydrochloric acid extracts of eight fresh water sediments.

Land use-changes and forest/soil degradation affect emissions of green house gases (GHGs) rather strongly, thereby causing global warming. These processes have led to a deep concern among the policy makers, scientists and public alike. For analysing causes and impacts of this complex problem, modelling has become increasingly more important, as evidenced by a plethora of models developed particularly during the last decade. This study reviews and synthesises the available models relating to landuse changes, forest/soil degradation and C sequestration in developing countries in general and the Hindu Kush Himalayan (HKH) region in particular. The major findings of these models in terms of factors affecting land-use changes especially, deforestation or agricultural expansion, are agricultural and timber prices, wage rates, risks in agriculture, population density in the rural areas, access to forestland, and titling security in frontier areas, and some of the government policies of economic reforms in the developing world. These findings, however, are space and time specific, and hence suggest for different policy options. A number of modelling techniques have been used in the past, such as, conceptual, analytical, empirical regression, and programming/simulation models. Both static and dynamic models have been used at different scales from household to global levels. Most studies in the HKH region are based on qualitative/descriptive methods using conceptual modelling techniques. Integrated models for analysing C sequestration dynamics as a function of land-use changes and forest/soil degradation in a holistic approach are emerging. Based on the review and synthesis of different techniques, a conceptual modelling framework is presented. This consists of a dynamic bio-economic modelling framework capable of capturing both socio-economic behaviour and bio-physical processes combined with geographical information systems/remote sensing techniques. Such modelling efforts have the potential of assisting policy makers and planners to identify and implement sustainable agriculture and forestry practices, leading to mitigation of CO 2 emissions in developing countries in general and the HKH region in particular. D

The degree of mixing of organic matter with minerals in organic and hemi-organic horizons of forest soils largely differs between humus types. As clay minerals might control the mobility of radiocesium in these forest floor horizons, plant contamination could greatly vary with the kind of humus. We measured the mobility of radiocesium in the upper O, OAh and Ah horizons of three acid forest soils with three distinct humus types: eumoder, dysmoder and fibrimor. We used two different approaches: a physico-chemical test quantifying the radiocesium interception potential (RIP) and a biological assay simulating an experimental rhizosphere. The results show that the Cs 137 horizon-to-plant transfer is directly governed by RIP, and thus by frayed edge sites born by weathered micaceous minerals. The inverse relationship between RIP and organic matter content indicates that in the three sites investigated the mixing of organic residues with Cs-fixing minerals is a key process in Cs mobility. These Cs-fixing clay 137 minerals indeed decrease in the sequence eumoder)dysmoder)fibrimor because they are more diluted in forest floor with less bioturbation. Our results suggest that humus type might be an important parameter in classifying forest soils with respect to their ability to transfer radiocesium to the above standing vegetation. ᮊ

Acidic deposition leads to the acidification of waters and accelerated leaching and depletion of soil base cations. The Bear Brook Watershed in Maine has used whole-watershed chemical manipulations to study the effects of elevated N and S on forest ecosystem function on a decadal time scale. The objectives of this study were to define the chemical and physical characteristics of soils in both the reference and treated watersheds after 17 years of treatment and assess evidence of change in soil chemistry by comparing soil studies in 1998 and 2006. Results from 1998 confirmed depletion of soil base cation pools and decreased pH due to elevated N and S within the treated watershed. However, between 1998 and