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1.
Factors controlling spatial distribution of soil acidification and Al forms in forest soils 总被引:3,自引:0,他引:3
Soil acidification and Al release in forest soils is controlled by a number of factors, like acid deposition, forest type, parent rock, altitude, etc. This paper studies the principal stand factors affecting spatial distribution of the content of KCl-extractable Al (Al(KCl), mainly exchangeable), Na4P2O7-extractable Al (Al(Na4P2O7), mainly organically bound), and other soil characteristics related to acidification in surface organic (O) and subsurface mineral (B) horizons in the Jizera Mountains region. Geostatistical methods were exploited. The highest Al(KCl) contents in the O horizons were related to high S and N content, low pH and low Ca and Mg content in soil. Liming decreased Al(KCl) contents in the O horizons. Al(Na4P2O7) in the O horizons was more abundant under spruce than under beech; in both horizons it was increased on the immission clear-cut areas populated by grass. Surface horizons are more sensitive to external influence (acid deposition, liming) and their spatial variation is stronger. In the mineral horizons, the effect of pedogenetic processes is more important. The effect of stand factors on Al behaviour is complex and often indirect, mediated for example by organic matter or soil reaction. It is difficult to clearly distinguish the effects of the particular factors. 相似文献
2.
Drábek O Borůvka L Pavlů L Nikodem A Pírková I Vacek O 《Journal of inorganic biochemistry》2007,101(9):1224-1233
Clear-cut areas formed after forest decline due to acid deposition, pest attacks, or wind-breaks in temperate mountainous regions are often populated by grass (mainly Calamagrostis villosa). This study focused on the changes of soil chemical characteristics under the grass cover replacing the forest, focusing mainly on aluminium (Al) speciation. Clear-cut area due to strong acid deposition in the Jizera Mountains (Northern Bohemia) was studied. The soils under grass cover exhibit higher pH values and lower exchangeable Al content compared to adjacent surviving forest. Mobile Al species under the grass have larger proportion of non-toxic organic complexes. The content of exchangeable base cations is slightly higher under the grass. The positive effect of grass on soil chemistry was enhanced by liming. The temporary grass cover can therefore improve soil chemical quality for following reforestation. However, the differences are generally limited to surface organic horizons. Similar results were found also on a bark-beetle clear-cut area in the Bohemian Forest (Southern Bohemia) with smaller acid deposition; nevertheless, most differences were not significant there. 相似文献
3.
Václav Tejnecký Ondřej Drábek Luboš Borůvka Antonín Nikodem Jan Kopáč Petra Vokurková Ondřej Šebek 《Biogeochemistry》2010,101(1-3):151-163
The Jizera Mountains area is affected by natural and anthropogenic acidification processes. The effect of acidification is reflected by presence of elevated amount of different Al forms in soil horizons. Changes of water extractable forms of Al (total $ {\text{Al}}_{{{\text{H}}_{2} {\text{O}}}} $ , species: Al(X)1+, Al(Y)2+ and Al3+) and other soil characteristics (e.g. DOC, pH) were investigated in forest soils from April to October 2008. Seasonal changes of Al forms were identified in organic F and H soil horizons. No significant effect of the soil type on Al forms was documented. Nevertheless, influence of vegetation cover (beech and spruce forest, clear-cut area) on Al(X)1+, Al(Y)2+ forms was proved. The results show that binding and mobility of Al forms are controlled mostly by pH and dissolved organic carbon (DOC). 相似文献
4.
rka Dlouh Lubo Borvka Lenka Pavl Vclav Tejnecký Ondej Drbek 《Journal of inorganic biochemistry》2009,103(11):1459-1464
The aim of this paper is to describe the influence of spruce (Picea abies) afforestation on soil chemical properties, especially on soil acidity and aluminium (Al) mobilization and speciation in soil. For our study we used a unique set of three adjacent plots, including a meadow and two spruce forest stands of different age, in otherwise comparable conditions. The plots were located in the region of Giant Mountains, north-eastern Czech Republic. In general, pH values decreased and Al concentrations increased significantly after afforestation. Speciation of KCl-extractable and water-soluble Al in soil samples was done by means of HPLC/IC method. The concentrations of Al(X)1+ and Al(Y)2+ forms (in both extracts) are higher in humic and organically enriched (Bhs) horizons. The highest concentration of Al3+ in both extracts is in the B horizons of old forest.Generally, in all studied stands majority of Al in aqueous extract is in the Al(X)1+ form, which indicates that a large amount of mobile Al is bound in organic complexes. It suggests that actual toxicity is rather low. On the other hand, we have proved that majority of KCl-extractable Al exists in Al3+ form. Thus we can conclude that disturbance of existing equilibrium may cause massive release of highly toxic Al3+ from soil sorption complex to the soil solution, and consequently it can endanger the whole ecosystem. Moreover, continuous soil acidification accelerated by anthropogenic factors leading to Al mobilization represents a chemical time bomb. 相似文献
5.
Possible method of aluminium speciation in forest soils 总被引:4,自引:0,他引:4
Labile Al forms and species can be a threat in acid soils due to their potential toxicity to plants. However, there is no universally accepted extraction method. Several extraction reagents for Al release from soil have been tested. KCl (0.5 or 1 M) is recommended for extraction of exchangeable Al, while 0.5 or 0.3 M CuCl(2) is suggested for extraction of 'weakly organically bound Al'. Both 0.1 and 0.05 M Na(4)P(2)O(7) are shown to be suitable for the extraction of 'total organically bound Al'. These extractions are relatively simple, robust, and applicable to different soils and soil horizons. In the second part of the paper, detailed speciation of exchangeable soil Al by means of an HPLC instrument equipped with an ion column (IC) is presented. An experimental set-up is described and tested on a set of samples. Interpretation of the speciation results is proposed, based on the separation of Al ions and Al complexes according to their charge. Speciation is shown to be dependent mainly on soil pH and organic matter quality. A general scheme of Al fractionation and speciation in soil is proposed. 相似文献
6.
Acid atmospheric deposition can cause losses of metal nutrients from the organic layer of a soil. The size of these losses
depend on the sizes of the different pools in which the metals are present, as these pools differ in mobility. The metal pools
in an organic soil layer of a Douglas fir forest in the Netherlands subjected to acid deposition were determined by means
of extractions and percolations. Na was mainly dissolved and exchangeably adsorbed, K dissolved, exchangeably adsorbed and
present in the soil microbial biomass, Ca exchangeably adsorbed and present in organic precipitates, Mg exchangeably adsorbed
and present in the soil biomass, and Mn exchangeably adsorbed and present in inorganic precipitates. The main part of the
metals was exchangeably adsorbed. The adsorption affinity increased in the order Na < K < Mg < Mn ≈ Ca. The vertical distribution
of the metals in the organic layer showed that all metals were continuously lost from the organic layer. The differences between
the metals in retention and vertical distribution patterns were in agreement with their differences in deposition rate, pool
distribution, and exchange affinity. Since the metals were mainly exchangeably adsorbed, and the acidifying cations dominated
the atmospheric deposition, acid deposition and cation exchange must be processes that strongly affect the losses of metals
from this organic soil layer. R F Huettl Section editor 相似文献
7.
8.
Sulfur speciation and distribution in soils and aboveground biomass of a boreal coniferous forest 总被引:1,自引:1,他引:0
Major sulfur pools are quantified in soils and aboveground biomass of a coniferous boreal forest. Total ecosystem S averages
1395 kg·ha−1 of which 98% is found in the soil, with 89% being in the mineral horizons. Organic S dominates in soil, tree parts (trunks,
branches + foliage, roots) and litterfall, ranging from 77 to 99% of total S concentration. Carbon-bonded S, ester sulfate
and SO4-S in soil profiles range respectively from 51–68%, 29–37% and 1–14% of total S concentrations and account respectively for
57, 33 and 10% of total S on an areal basis. Adsorbed SO4 accounts for 82% of total SO4, and can be predicted from Al bound to organic matter, amorphous Al and pH (r2 = 0.81). There is a strong relationship between % carbon and carbon-bonded S in 4 of the 5 soil horizons studied which represent
over 95% of the total soil organic matter, whereas ester sulfate is related to % carbon in 3 soil horizons representing only
37% of the soil organic matter. An analysis of atmospheric S loading and S data for 10 forested sites in Europe and North
America suggests that the size of the organic S pool in forested systems is independent of atmospheric loading. 相似文献
9.
Aluminum and iron chemistry in the O horizon changed by a shift in tree species composition 总被引:2,自引:0,他引:2
In the present study we characterized the buffering system including aluminum in the organic surface horizon (O) of field experiments with replicated plots of pure Norway spruce (Picea abies (L.) Karst) and replicated plots of spruce with a birch (Betula pendula Roth and B. pubescens Ehrh.) admixture. Our results show that a change in tree species composition may have a rather large, short-term (12 years) effect on the concentration of organically bound aluminum in the humus layer (H) of the O horizon. The pure spruce plots had a significantly higher concentration of exchangeable aluminum (Ale) and organically bound (pyrophosphate extractable) aluminum (AlP) in the H layer and a lower concentration of each base cation. Furthermore, our results confirm earlier findings that aluminum has base cation properties in acidic organic horizons. Thus, the change in tree species composition did not affect the pH in spite of a change in base saturation, because base cations were mainly compensated for by aluminum. The change in organically bound aluminum was accompanied by a similar change in organically bound pyrophosphate extractable iron (FeP). The observed differences between the mixed and pure spruce plots in the amounts of AlP and FeP in the H layer could not be explained by estimated differences in biocycling of Al and Fe either by above-ground litterfall or by root turnover. 相似文献
10.
11.
Nicole S. Nowinski Susan E. Trumbore Edward A. G. Schuur Michelle C. Mack Gaius R. Shaver 《Ecosystems》2008,11(1):16-25
Nutrient availability in the arctic is expected to increase in the next century due to accelerated decomposition associated
with warming and, to a lesser extent, increased nitrogen deposition. To explore how changes in nutrient availability affect
ecosystem carbon (C) cycling, we used radiocarbon to quantify changes in belowground C dynamics associated with long-term
fertilization of graminoid-dominated tussock tundra at Toolik Lake, Alaska. Since 1981, yearly fertilization with nitrogen
(N) and phosphorus (P) has resulted in a shift to shrub-dominated vegetation. These combined changes have altered the quantity
and quality of litter inputs, the vertical distribution and dynamics of fine roots, and the decomposition rate of soil organic
C. The loss of C from the deep organic and mineral soil has more than offset the C accumulation in the litter and upper organic
soil horizons. In the litter and upper organic horizons, radiocarbon measurements show that increased inputs resulted in overall
C accumulation, despite being offset by increased decomposition in some soil pools. To reconcile radiocarbon observations
in the deeper organic and mineral soil layers, where most of the ecosystem C loss occurred, both a decrease in input of new
root material and a dramatic increase of decomposition rates in centuries-old soil C pools were required. Therefore, with
future increases in nutrient availability, we may expect substantial losses of C which took centuries to accumulate. 相似文献
12.
Vertical distribution of biological and geochemical phosphorus subcycles in two southern Appalachian forest soils 总被引:8,自引:4,他引:4
We measured Al, Fe, and P fractions by horizon in two southern Appalachian forest soil profiles, and compared solution PO4
–1 removal in chloroform-sterilized and non-sterilized soils, to determine whether biological and geochemical P subcycles were vertically stratified in these soils. Because organic matter can inhibit Al and Fe oxide crystallization, we hypothesized that concentrations of non-crystalline (oxalate-extractable) Al (Al0) and Fe (Fe0), and concomitantly P sorption, would be greatest in near-surface mineral (A) horizons of these soils.Al0 and Fe0 reached maximum concentrations in forest floor and near-surface mineral horizons, declined significantly with depth in the mineral soil, and were highly correlated with P sorption capacity. Small pools of readily acid-soluble (AF-extractable) and readily-desorbable P suggested that PO4
3– was tightly bound to Al and Fe hydroxide surfaces. P sorption in CHCl3-sterilized mineral soils did not differ significantly from P sorption in non-sterilized soils, but CHCl3 sterilization reduced P sorption 40–80% in the forest floor. CHCl3 labile (microbial) P also reached maximum concentrations in forest floor and near-surface mineral horizons, comprising 31–35% of forest floor organic P. Combined with previous estimates of plant root distributions, data suggest that biological and geochemical P subcycles are not distinctly vertically stratified in these soils. Plant roots, soil microorganisms, and P sorbing minerals all reach maximum relative concentrations in near-surface mineral horizons, where they are likely to compete strongly for PO4
3– available in solution. 相似文献
13.
Previous studies have found that root carbon inputs to the soil can stimulate the mineralization of existing soil carbon (C)
pools. It is still uncertain, however, whether this “primed” C is derived from elevated rates of soil organic matter (SOM)
decomposition, greater C release from microbial pools, or both. The goal of this research was to determine how the activities
of the microbial exoenzymes that control SOM decomposition are affected by root C inputs. This was done by manipulating rhizodeposition
with tree girdling in a coniferous subalpine forest in the Rocky Mountains of Colorado, USA, and following changes in the
activities of nine exoenzymes involved in decomposition, as well as soil dissolved organic C, dissolved organic and inorganic
nitrogen (N), and microbial biomass C and N. We found that rhizodeposition is high in the spring, when the soils are still
snow-covered, and that there are large ephemeral populations of microorganisms dependent upon this C. Microbial N acquisition
from peptide degradation increased with increases in microbial biomass when rhizodeposition was highest. However, our data
indicate that the breakdown of cellulose, lignin, chitin, and organic phosphorus are not affected by springtime increases
in soil microbial biomass associated with increases in rhizodeposition. We conclude that the priming of soil C mineralization
by rhizodeposition is due to growth of the microbial biomass and an increase in the breakdown of N-rich proteins, but not
due to increases in the degradation of plant litter constituents such as cellulose and lignin. 相似文献
14.
The effects of three S deposition scenarios — 50% reduction, no change, and 100% increase — on the cycles of N, P, S, K, Ca, and Mg in a mixed deciduous forest at Coweeta, North Carolina, were simulated using the Nutrient Cycling model (NuCM). The purpose of this exercise was to compare NuCM's output to observed soil and streamwater chemical changes and to explore NuCM's response to varying S deposition scenarios. Ecosystem S content and SO4
2– leaching were controlled almost entirely by soil SO4
2– adsorption in the simulations, which was in turn governed by the nature of the Langmuir isotherm set in the model. Both the simulations and the 20-year trends in streamwater SO4
2– concentration suggest that the ecosystem is slowly becoming S saturated. The streamwater data suggest S saturation is occurring at a slower rate than indicated by the simulations, perhaps because of underestimation of organic S retention in the model. Both the simulations and field data indicated substantial declines in exchangeable bases in A and BA soil horizons, primarily due to vegetation uptake. The correspondence of model output with field data in this case was a result of after-the-fact calibration (i.e. setting weathering rates to very low values) rather than prediction, however. Model output suggests that soil exchangeable cation pools change rapidly, undergoing annual cycles and multi-decade fluctuations.Varying S deposition had very little effect upon simulated vegetation growth, nutrient uptake, or N cycling. Varying S deposition strongly affected simulated Ca2+. Mg2+, K+, and P leaching but caused little change in soil exchangeable pools of Ca2+ K+, or P because soil exchangeable pools were large relative to fluxes. Soil exchangeable Mg2+ pools were reduced by high rates of S deposition but remained well above levels sufficient for tree growth. Although the total soil pools of exchangeable Ca2+ and K+ were only slightly affected by S deposition, there was a redistribution of Ca2+ and K+ from upper to lower horizons with increasing S deposition, causing increased base saturation in the deepest (BC) horizon. The 100% increased S deposition scenario caused increasing peaks in simulated Al3+ concentrations in A horizons after 25 years as a result of large seasonal pulses of SO4
2– and lowered base saturation. Simulated soil solution Al3+ concentrations remained well below toxicity thresholds for selected tree species at the site. 相似文献
15.
Relations of mineral-soil C and N to climate and texture: regional differences within the conterminous USA 总被引:4,自引:0,他引:4
Soil is a prominent component of terrestrial C and N budgets. Soil C and N pools are influenced by, and may reciprocally influence,
many environmental factors. Our objective was to determine the quantitative relations of surface mineral-soil organic C, N,
and C/N ratios to climate and soil texture across seven ecological regions that make up the conterminous USA. Up to 608 soil
profiles per region and their corresponding climates were evaluated with regression analysis. The organic C pool (kg C m−2) in the upper 20 cm of mineral soil was positively related to mean annual precipitation, evapotranspiration and clay content
in all regions. It was negatively related to a temperature/precipitation index in all regions and negatively related to mean
annual temperature, except in the northwest temperate forest region. Soil C/N ratios were negatively related to clay or silt
content in all regions. These relations are consistent with concepts of moisture and temperature controls on detrital production,
differential effects of temperature on detrital production and decomposition, and stabilization of organic matter by clay
and silt. Differences in quantitative relations among regions may be related to vegetation-composition effects on soil organic
matter processes, clay mineralogy, and faunal mixing of surface organic horizons with mineral soil. Regional differences also
occurred in the importance of climate vs. soil texture in explaining the variability in soil C. The regional differences indicate
the importance of using region-specific, rather than generalized, equations for projecting long-term soil responses to climate
change and for conducting ecosystem-model calibration or validation. 相似文献
16.
Michelle L. McCrackin Tamara K. Harms Nancy B. Grimm Sharon J. Hall Jason P. Kaye 《Biogeochemistry》2008,87(2):143-155
Terrestrial desert ecosystems are strongly structured by the distribution of plants, which concentrate resources and create
islands of fertility relative to interplant spaces. Atmospheric nitrogen (N) deposition resulting from urbanization has the
potential to change those spatial patterns via resource inputs, resulting in more homogeneous soil resource availability.
We sampled soils at 12 desert remnant sites around Phoenix, Arizona along a model-predicted gradient in N deposition to determine
the degree to which deposition has altered spatial patterns in soil resource availability and microbial activity. Soil microbial
biomass and abundance were not influenced by atmospheric N deposition. Instead, plant islands remained strong organizers of
soil microbial processes. These islands of fertility exhibited elevated pools of resources, microbial abundance, and activity
relative to interspaces. In both plant islands and interspaces, soil moisture and soil N concentrations predicted microbial
biomass and abundance. Following experimental wetting, carbon dioxide (CO2) flux from soil of interspaces was positively correlated with N deposition, whereas in plant islands, soil CO2 flux was positively correlated with soil moisture content and soil organic matter. Soil CO2 flux in both patch types showed rapid and short-lived responses to precipitation, demonstrating the brief time scales during
which soil biota may process deposited materials. Although we observed patterns consistent with N limitation of microbes in
interspaces, we conclude that atmospheric N deposition likely accumulates in soils because microbes are primarily limited
by water and secondarily by carbon or nitrogen. Soil microbial uptake of atmospherically deposited N likely occurs only during
sparse and infrequent rainfall. 相似文献
17.
The wetland Argialbolls pedon was chosen to investigate the effects of pedogenic processes and anthropogenic activities on the vertical distribution of lead and mercury concentration and to assess the potential use of soil as an archive of atmospheric Pb and Hg pollution. The soil was sampled from 5 cm from the surface to a depth of 90 cm at two locations in the Sanjiang Plain in northeastern China. The soil was analyzed for pH, soil organic matter (SOM), Fe, Mn, and Al. The results indicate that the SOM concentration gradually decreased with depth, while Fe and Mn were reductively leached from the upper horizons and accumulated significantly in the lower argillic horizons. Atmospheric Pb and Hg deposition and their redistribution during the pedogenic process led to a unique vertical distribution in the wetland Argialbolls. Overall, Pb was leached from the upper horizons and then accumulated in the lower argillic horizons. However, the Hg concentration decreased with depth, following the SOM distribution. The Pb concentration was significantly correlated to the Fe and Mn concentrations in the Argialbolls profiles, while the Hg concentration was significantly correlated with SOM. Post-depositional mobility along the wetland Argialbolls profile is higher for Pb and low for Hg. Therefore, the Argialbolls profile does not provide an accurate reconstruction of atmospheric Pb deposition, but might provide an accurate reconstruction of net atmospheric Hg deposition. 相似文献
18.
The effects of soil horizons and faunal excrement on bacterial distribution in an upland grassland soil 总被引:1,自引:0,他引:1
The density and spatial location of bacteria were investigated within different horizons of an upland grassland soil before and after a liming treatment to increase the numbers of large soil fauna. Bacterial cells were located by image analysis of stained thin sections and densities calculated from these data. Excrement from macro- and meso-fauna was identified using micromorphology and the densities of bacteria on specific areas of excrement measured by image analysis. There were significant differences among horizons in the density of bacterial cells, with the minimum density found in the horizon with least evidence of earthworm activity, but no difference in density between the organic H and organo-mineral Ah horizons. Soil improvement by liming significantly increased bacterial densities in all three horizons, with the greatest increase found in the horizon with the smallest density before liming. There were no differences in bacterial density between areas dominated by excrement from earthworms and excrement from enchytraeids, although densities in both areas were significantly increased by liming. Variability in bacterial density at spatial scales of less than 1 mm was linked to the occurrence of excrement. Bacterial densities within areas of both types of excrement were significantly greater than those in the surrounding soil. However, the frequency distribution of the ratios of density in excrement to that in the soil was bimodal, with a majority of occurrences having a ratio near 1 and only some 20-30% having a much larger ratio. These variations can probably be explained by variations in the age of the excrement and its suitability as a substrate. 相似文献
19.
鼎湖山土壤有机质δ13C时空分异机制 总被引:5,自引:2,他引:3
根据鼎湖山若干海拔部位土壤剖面薄层取样样品有机质含量、14C测年及δ13C结果,研究土壤有机质δ13C时空分异机制.结果表明,不同海拔土壤剖面有机质δ13C深度特征受控于剖面发育进程,与有机质组成及其分解过程密切相关.植被枯落物成为表土层有机质以及表土层被埋藏后的有机质更新过程,均存在碳同位素分馏效应,有机质δ13C显著增大.相对于地表植被枯落物δ13C,表土层有机质δ13C增幅取决于表土有机质更新速率.表土有机质δ13C与植被枯落物δ13C均随海拔升高而增大,说明植被构成随海拔升高呈规律性变化.这与鼎湖山植被的垂直分布一致.不同海拔土壤剖面有机质δ13C深度特征类似,有机质含量深度特征一致,有机质14C表观年龄自上向下增加.这是剖面发育过程中有机质不断更新的结果.土壤剖面有机质δ13C最大值深度与14C弹穿透深度的成因和大小不同,均反映地貌与地表植被对有机碳同位素深度分布的控制. 相似文献
20.
Aaron B. Shiels Christine A. West Laura Weiss Paul D. Klawinski Lawrence R. Walker 《Plant Ecology》2008,195(2):165-178
Tropical storms are the principal cause of landslides in montane rainforests, such as the Luquillo Experimental Forest (LEF)
of Puerto Rico. A storm in 2003 caused 30 new landslides in the LEF that we used to examine prior hypotheses that slope stability
and organically enriched soils are prerequisites for plant colonization. We measured slope stability and litterfall 8–13 months
following landslide formation. At 13 months we also measured microtopography, soil characteristics (organic matter, particle
size, total nitrogen, and water-holding capacity), elevation, distance to forest edge, and canopy cover. When all landslides
were analyzed together, plant biomass and cover at 13 months were not correlated with slope stability or organic matter, but
instead with soil nitrogen, clay content, water-holding capacity, and elevation. When landslides were analyzed after separating
by soil type, the distance from the forest edge and slope stability combined with soil factors (excluding organic matter)
predicted initial plant colonization on volcaniclastic landslides, whereas on diorite landslides none of the measured characteristics
affected initial plant colonization. The life forms of the colonizing plants reflected these differences in landslide soils,
as trees, shrubs, and vines colonized high clay, high nitrogen, and low elevation volcaniclastic soils, whereas herbs were
the dominant colonists on high sand, low nitrogen, and high elevation diorite soils. Therefore, the predictability of the
initial stage of plant succession on LEF landslides is primarily determined by soil characteristics that are related to soil
type. 相似文献