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1.
The lignite and pyrite containing spoil substrates of the Lusatian mining district are marked by very high acidity and salt
concentrations due to pyrite oxidation and by a very low content of pedogenic organic matter and nutrients. The effects of
fly ash application to neutralize the produced acid and of organic waste material application to improve the ecological soil
functions were studied considering the carbon and nitrogen cycling. Nineteen, 38 and 57 t ha−1 sewage sludge and 22, 44 and 66 t ha−1 compost were applied to ameliorated lignite and pyrite containing substrate. An automated soil microcosm system was used
to analyse the solid, gaseous and liquid phases. Almost 9% of total N applied with sewage sludge (620, 1240 and 1860 t N ha−1 applied) were lost over a period of 150 days mainly as NO3-N. The total N losses from compost treatments were three times lower (2.8–3.1% of applied Nt) and occurred in similar quantities
as NH4-N and NO3-N. Only sewage sludge treatments showed slightly increased N2O emissions at the beginning of the experiment. CO2 emissions determined the carbon losses of all treatments. The C losses amounted to 3.2–4.7% and 1.5–2.7% of Ct applied with sewage sludge and with compost, respectively.
This revised version was published online in June 2006 with corrections to the Cover Date.
This revised version was published online in June 2006 with corrections to the Cover Date.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
2.
On the basis of long-term field experiments, the impact is demonstrated of the periodic application of organic fertilizers
on the accumulation of organic matter and the development of the micro-pollutant content of reclaimed loess soils of the Rhineland
lignite mining area under agricultural use. The oldest of these experiments (‘Berrenrath Humus Accumulation Experiment’) was
begun in 1969. The results show that the regular input of organic matter (e.g. manure, waste compost, sewage sludge) favors
the accumulation of soil organic matter (SOM). However, the type of organic material applied seems to be less important to
the long-term accumulation process than the application rate. This is also true for composted and uncomposted manure, if the
decay of organic matter during the composting process is taken into account. Nevertheless, the application of similar amounts
of organic C in the form of manure resulted in a higher accumulation of SOM in a nitrogen-reduced farming system. Depending
on the treatment, accumulation rates were between 0.02 and 0.08% SOM per year with values decreasing with time. From these
results, it is estimated that reclaimed soils will take much longer to reach the former SOM level than was previously assumed.
However, it is important to determine which SOM level is adequate for different soil functions (e.g. production function,
filter and buffer function, transformation function), and whether the young SOM of reclaimed soils has the same properties
as older SOM in undisturbed topsoils. As was expected, long-term fertilization with sewage sludge and waste compost led to
an accumulation of some micro-pollutants in the topsoils treated. Nevertheless, the observed concentrations are quite low
compared to background levels in topsoils of rural regions in North Rhine-Westphalia.
This revised version was published online in June 2006 with corrections to the Cover Date.
This revised version was published online in June 2006 with corrections to the Cover Date.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
3.
Short-term mineralization of maize residues in soils as determined by carbon-13 natural abundance 总被引:2,自引:0,他引:2
Studies of soil organic matter equilibria must include estimates of C turnover. The objective of this study was to provide
data on how the natural 13C abundance method can be used to determine the flow of C from C4 residues and soil organic matter (C3-source) in a short-term incubation. Corn residue was added at a rate of 5.7 mg C g−1 soil to two soils, a clay and a sandy clay loam. During the course of a 35-day incubation in a CO2-free system, CO2-C and 13C natural abundance of the respired CO2 were measured. About 20% of the corn residue-C added was mineralized in both soils as determined from the CO2 respired and the 13C natural abundance of the respired CO2. Mineralization of the added residues was also calculated as the difference of the total amount of the respired CO2-C between the control and the corn residue-treated soils divided by the total amount of corn residue-C. Values were 35% for
the clay soil, and 30% for the sandy clay loam soil. The difference in values calculated from the 13 C natural abundance and the difference method was due to mineralization of the indigenous soil organic C resulting from the
addition of corn residues. Use of the natural 13C abundance method could determine the degree of ‘priming effect’ in soils amended with C4-C residues.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
4.
It is a necessity to have a successful method to separate, quantify and define the active and passive soil organic matter
pools for appropriate verification of models. In this study, the organic carbon content of long-term bare fallow soils was
used as an indicator of the size of the stable soil organic matter pool. Although soil texture and soil structure are widely
accepted as having an influence on the stable pool, most soil organic models neglect the relationship between soil structure
and carbon stabilization. Therefore, the aim of this presentation is to estimate the size of the stable carbon pool and to
relate it to soil texture and structure properties. It was calculated that over 50 yr, under bare fallow conditions, the relative
decrease in the amount of carbon (C) for the most stable pools ranged between 2 and 12%. In comparison, for the less stabilized
pools the relative decrease was calculated from 50 to 100%. This indicates that the organic carbon content of long-term bare
fallow soils should be very similar to the size of the most stable C pool. We also observed that the amounts of carbon associated
with primary particles <20 μm for numerous soils with contrasting carbon content, soil texture, and management practices showed
a lower and an upper limit. Both these limits and the carbon content of long-term bare fallow soils (which were assumed to
be similar to the size of the stable pool) were related to the content of primary particles <20 μm in the soil. To calculate
these relationships, an equation was used including one term to describe the influence of soil texture and another to describe
that of soil structure. The calculated regression for the bare fallow soils corresponded very well to the lower limit of carbon
content associated with primary particles <20 μm. The upper limit was estimated only by increasing the regression parameter
which is related to the amount of C per unit primary particles <20 μm. Considering the many published results of the influence
of soil texture and structure on carbon stabilization processes in soil, the stable pool may be defined as the capacity of
soils to sorb C. The upper limit of carbon content associated with primary particles <20 μm may be interpreted as the capacity
of soil to protect C.
This revised version was published online in June 2006 with corrections to the Cover Date.
This revised version was published online in June 2006 with corrections to the Cover Date.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
5.
Greenhouse experiments were conducted in order to determine for carboniferous and non-carboniferous mine spoil substrates
from the Lusatian lignite mining area (i) the suitable extraction method for plant available P, (ii) the soil capacity for
immobilisation of P and (iii) the impact of sewage sludge and compost on P availability. Ca-lactate extraction (DL) and NH4F-extraction (Bray) were both suited equally well for the determination of plant available P as they extracted similar amounts
of P on both spoils, they showed a close correlation with each other (R=0.97 2) and they showed a close relation with plant P uptake (R2=0.63 and R2=0.66, respectively). Phosphorus recovery from limed carboniferous mine spoil five days after mineral fertiliser application
was only 50%, and decreased to 30% after 54 days. As pH was increased from 3.0 to 5.0 the amount of P immobilised decreased
only by about 5%. Several pH dependent processes of P immobilisation and release could occur concurrently counteracting each
other. One process could be P sorption to newly formed hydroxy-Al-surfaces but P desorption could also take place as pH increases
by decreasing surface positive charge. Finally, due to high Ca concentrations in spoil solution formation of Ca-phosphates,
even at lower pH values, cannot be excluded as a possible mechanism of P immobilisation. As part of the P is bound in organic
matter, application of P with organic matter resulted in a lower P recovery compared to mineral P-fertiliser. However, the
amount of P recovered did not differ between carboniferous and non-carboniferous mine spoil, if P was applied in the form
of organic matter, indicating that the application of P with organic matter might be a measure to overcome P immobilisation
in carboniferous mine spoils.
This revised version was published online in June 2006 with corrections to the Cover Date.
This revised version was published online in June 2006 with corrections to the Cover Date.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
6.
Many mine spoils present at the surface of reclamation sites in the Lower Lusatian mining district are carboniferous substrates,
i.e. contain geogenic organic matter. Depending on its susceptibility to microbial degradation, geogenic organic matter might
influence the establishment of a carbon requiring microflora in mine spoils. As geogenic organic matter contains substantial
amounts of organic nitrogen it is also a potential source for plant available N. The objective of the present study was to
quantify C and N mineralisation and microbial biomass in geogenic organic matter present at reclamation sites in Lower Lusatia.
We also studied, whether these properties can be influenced by raising the originally low pH to near neutral conditions. In
laboratory incubation studies, the rates of CO2 evolution and net N mineralisation were determined in geogenic organic matter and carboniferous mine spoil with and without
addition of lime. At the same time, microbial biomass carbon was estimated. As a reference, soil organic matter originating
from the humus layer of a 60-year-old Pinus sylvestris stand was used. As indicated by the initial rates of C mineralisation,
geogenic carbon was microbially available but to a lower extent than soil organic carbon. During incubation, C mineralisation
remained constant or tended to increase with time, depending on the origin of the sample, while it decreased in soil organic
matter. Unlike in soil organic matter, in geogenic organic matter and carboniferous mine spoil, C mineralisation was not consistently
promoted by lime addition. Prior to incubation, microbial biomass in geogenic organic matter and carboniferous mine spoil
was about 10-fold lower than in soil organic matter and tended to increase with incubation time while it decreased in soil
organic matter. Similar to C mineralisation, microbial biomass in geogenic organic matter increased after liming, while it
declined in carboniferous mine spoil immediately after lime addition. Rates of net N mineralisation were very low in geogenic
organic matter and carboniferous mine spoil regardless of the length of incubation and could not be enhanced by raising the
pH. It was concluded, that in mine spoils where accumulation of soil organic matter has not yet occurred, geogenic organic
matter can be favourable for the establishment of a heterotrophic microflora. However, in the short term, geogenic matter
is no source for plant available N in mine spoils.
This revised version was published online in June 2006 with corrections to the Cover Date.
This revised version was published online in June 2006 with corrections to the Cover Date.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
7.
The individual-based combined forest model EFIMOD including the soil-sub model SOMM has been used for the simulation of Scots
pine stand growth and soil organic matter (SOM) accumulation on a humus-free bare mineral surface. The growth of Scots pine
plantation, with an initial density of 10 000 trees ha−1 and average tree biomass of 0.01 kg was simulated for 50 yr under Central European climatic conditions (i) with varying atmospheric
nitrogen inputs and (ii) different rates of initial application of raw undecomposed organic material or compost, on humus-free
parent material. The accumulation of typical raw humus was simulated in all cases. The accumulation was most intensive in
the simulation of high atmospheric nitrogen input. The humus pool in the mineral topsoil was small but achieved its maximum
value with compost application. SOM nitrogen accumulation was scant in all cases, except the compost applications with low
atmospheric nitrogen input. No statistically significant differences of SOM and stand parameters were found between variants
without organic matter and those with low input of organic manure. However, the maximum relative rate of SOM and nitrogen
accumulation was found in the scenario without organic manure, under slowly growing unstable Scots pine plantation.
This revised version was published online in June 2006 with corrections to the Cover Date.
This revised version was published online in June 2006 with corrections to the Cover Date.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
8.
Kenji Ono Syuntaro Hiradate Sayaka Morita Kenji Ohse Keizo Hirai 《Plant and Soil》2011,338(1-2):171-181
We quantitatively clarified the early humification processes on Japanese cedar and Hinoki cypress forest floors by using a litterbag experiment and the solid-state 13C CPMAS NMR technique. There was no significant effect on litter mass loss during early humification between both coniferous litters regardless of the shape of their needles. Carbon composition in both litters showed similar trends during early humification. A/O-A as a humification index was low, around 0.6, in both litters throughout the experiment period although 60% of litter mass was lost. Coniferous litter incubated for 3 years might not be well-humified and would be susceptible to physical fragmentation. Carbon mass loss rates in conifers were in the following order: O-alkyl > aliphatic > aromatic > carbonyl carbons, differing with hardwoods. Conifers had concomitantly higher and lower mass loss rates of aliphatic and aromatic carbons than hardwoods. Soil organic carbon (SOC) accumulated in topsoil for conifers had relatively high and low contents of aliphatic and aromatic carbons than that for hardwood. These compositional differences of SOC among forests could be caused by the high and low supply rates of aliphatic and aromatic carbons from litter to topsoil. Consequently, initial litter nature and humification processes can affect the compositional qualities of SOC accumulated in soil. 相似文献
9.
Impact of some ecological factors on the occurrence of poultry soil-inhabiting keratinophiles 总被引:1,自引:1,他引:0
Investigations were conducted to assess the ecological factors governing distribution and survival of keratinophilic fungi
in poultry farm soils. All the poultry farm soils were rich in humus and the keratinophilic fungi were generally found to
be proportional to the soil organic matter. These soils were nearly neutral to weakly alkaline and organically rich with a
high content of organic carbon, nitrogen, phosphorus, potassium, magnesium, calcium and iron.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
10.
Individual trees are known to influence soil chemical properties, creating spatial patterns that vary with distance from the
stem. The influence of trees on soil chemical properties is commonly viewed as the agronomic basis for low-input agroforestry
and shifting cultivation practices, and as an important source of spatial heterogeneity in forest soils. Few studies, however,
have examined the persistence of the effects of trees on soil after the pathways responsible for the effects are removed.
Here, we present evidence from a Mexican dry forest indicating that stem-related patterns of soil nutrients do persist following
slash-and-burn removal of trees and two years of cropping. Pre-disturbance concentrations of resin extractable phosphorus
(P), bicarbonate extractable P, NaOH extractable P, total P, total nitrogen (N) and carbon (C), KCl extractable nitrate (NO3
-), and net N mineralization and nitrification rates were higher in stem than dripline soils under two canopy dominant species
of large-stemmed trees with contrasting morphologies and phenologies (Caesalpinia eriostachys Benth. and Forchhammeria pallida
Liebm.). These stem effects persisted through slash burning and a first growing season for labile inorganic and organic P,
NaOH inorganic P, and plant-available P, and through a second growing season for labile organic P, NaOH organic P, and plant-available
P. While stem effects for extractable NO3
-, net nitrification rates, total N and C disappeared after felling and slash burning, these stem effects returned after the
first growing season. These results support the view that tree-influenced patterns of soil nutrients do persist after tree
death, and that trees contribute to the long-term spatial heterogeneity of forest soils.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
11.
Soil respiration fluxes measured along a hydrological gradient in a Norway spruce stand in south Sweden (Skogaby) 总被引:7,自引:0,他引:7
Soil respiration fluxes were measured continuously in order to assess the degree to which they were influenced by spatial
and temporal variation in soil moisture. The synergistic effects of the variation in soil moisture with the one in soil temperature, soil organic matter and global
radiation on respiration fluxes were also analysed. The measurements were performed using an open chamber system along a hydrological
gradient in a Norway spruce forest in south Sweden (Skogaby) for 3 weeks in June 1995. The measured soil respiration fluxes
were quite stable and somewhat larger compared with those reported in literature. The experiment took place during the shoot
elongation period with intensive nutrient uptake, and it might be that soil respiration was dominated by mycorrhizal activity.
Variation in the moisture content of the litter layer accounted for most of the spatial variation in respiration fluxes.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
12.
To fulfill the purpose as a sink for trace elements, soils must not be overloaded with As and Cd. Therefore, it is necessary
to get knowledge of the sorption capacities of soils on a regional scale. The determination of these sorption capacities for
large areas is, however, impeded by the great expenditure of laboratory work involved. With data presented here retention
capacities for cadmium and arsenic from routinely determined soil parameters are estimated. In batch experiments the sorption
behaviour of 40 soils from the area of Freiberg/Saxony in Germany was examined. The obtained sorption isotherms from the laboratory
were fitted to the Freundlich equation (S = k*Cm). The two constants (k, m) of this equation were used for multiple linear regression to correlate the sorption capacity and
the soil parameters, namely clay content, pH value, total organic carbon, and dithionite extractable Fe contents. Due to long
lasting ore mining of Freiberg there exist high background levels in that area for the two surveyed elements As and Cd. Therefore,
this study offers two different mathematical procedures to take these contaminations into account. Thus the experimental data
were corrected before they were fitted to Freundlich and pedotransfer equations were determined. Using the transfer equation,
parameter k and m for cadmium sorption could be estimated with statistical certainties of 91% and 61% (adjusted R2), respectively, whereas the predictability for the arsenic sorption is not practicable because achieved R2 values are very low (17% and 7%).
This revised version was published online in June 2006 with corrections to the Cover Date.
This revised version was published online in June 2006 with corrections to the Cover Date.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
13.
Schaaf W. Gast M. Wilden R. Scherzer J. Blechschmidt R. Hüttl R. F. 《Plant and Soil》1999,213(1-2):169-179
Lignite and pyrite contents in the dump materials of the Lusatian opencast mining district in East Germany result in high
acidification and salinization potentials. These extreme conditions require considerable amounts of alkaline materials like
ash or lime to enable recultivation and revegetation. Investigations at chronosequence sites on different mining substrates
show characteristic developments of the soil solution chemistry. Processes like weathering of primary and formation of secondary
mineral phases, acid production and buffering, and their impacts on both the solid and the liquid soil phase result in high
temporal and spatial dynamics especially in the initial phase of soil and ecosystem development. To study these processes
we continuously collected soil solutions from different soil depths at seven sites with two representative soil substrates.
All sites were afforested with pine and cover stand ages from 1 to 60 yr. The results show that actual pyrite oxidation occurs
at the youngest sites on lignite and pyrite containing substrates leading to extremely low pH values and high Fen+ and SO4
2- concentrations. The considerable acid production causes weathering of aluminium silicates resulting in high Aln+ concentrations. Ca2+ concentrations are unexpectedly high even at low pH showing no correlation to amelioration amounts or depths. Therefore it
seems most probable that these mining substrates contain geogenic Ca sources. The transport of dissolved weathering products
is limited due to low leaching rates enabling formation of secondary phases which control the actual composition of the soil
solution. Depth gradients of the soil solution composition at the chronosequence sites point to a gradual transport and leaching
of these secondary phases from the soil profiles. Soil solution composition and dynamics at lignite and pyrite free sites
show completely different patterns and have a higher potential for successful sustainable recultivation.
This revised version was published online in June 2006 with corrections to the Cover Date.
This revised version was published online in June 2006 with corrections to the Cover Date.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
14.
Carbon rhizodeposition and root respiration during eight development stages of Lolium perenne were studied on a loamy Gleyic
Cambisol by 14CO2 pulse labelling of shoots in a two compartment chamber under controlled laboratory conditions. Total 14CO2 efflux from the soil (root respiration, microbial respiration of exudates and dead roots) in the first 8 days after 14C pulse labelling decreased during plant development from 14 to 6.5% of the total 14C input. Root respiration accounted for was between 1.5 and 6.5% while microbial respiration of easily available rhizodeposits
and dead root remains were between 2 and 8% of the 14C input. Both respiration processes were found to decline during plant development, but only the decrease in root respiration
was significant. The average contribution of root respiration to total 14CO2 efflux from the soil was approximately 41%. Close correlation was found between cumulative 14CO2 efflux from the soil and the time when maximum 14CO2 efflux occurred (r=0.97). The average total of CO2 Defflux from the soil with Lolium perenne was approximately 21 μg C-CO2 d−1 g−1. It increased slightly during plant development. The contribution of plant roots to total CO2 efflux from the soil, calculated as the remainder from respiration of bare soil, was about 51%. The total 14C content after 8 days in the soil with roots ranged from 8.2 to 27.7% of assimilated carbon. This corresponds to an underground
carbon transfer by Lolium perenne of 6–10 g C m−2 at the beginning of the growth period and 50–65 g C m−2 towards the end of the growth period. The conventional root washing procedure was found to be inadequate for the determination
of total carbon input in the soil because 90% of the young fine roots can be lost.
This revised version was published online in June 2006 with corrections to the Cover Date.
This revised version was published online in June 2006 with corrections to the Cover Date.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
15.
Soil organic matter biochemistry and potential susceptibility to climatic change across the forest-tundra ecotone in the Fennoscandian mountains 总被引:5,自引:0,他引:5
SOFIE SJÖGERSTEN BENJAMIN L. TURNER† NATHALIE MAHIEU‡ LEO M. CONDRON§ PHILIP A. WOOKEY 《Global Change Biology》2003,9(5):759-772
We studied soil organic carbon (C) chemistry at the mountain birch forest‐tundra ecotone in three regions of the Fennoscandian mountain range with comparable vegetation cover but contrasting degrees of continentality and latitude. The aim of the study was to identify functional compound classes and their relationships to decomposition and spatial variation across the ecotone and latitudinal gradient. Solid‐state 13C nuclear magnetic resonance (CPMAS 13C NMR) was used to identify seven functional groups of soil organic C: alkyls, N‐alkyls, O‐alkyls, acetals, aromatics, phenolics and carboxyls. N‐alkyls, O‐alkyls and acetals are generally considered labile substrates for a large number of saprotrophic fungi and bacteria, whilst phenolics and aromatics are mainly decomposed by lignolytic organisms and contribute to the formation of soil organic matter together with aliphatic alkyls and carboxyls. All soils contained a similar proportional distribution of functional groups, although relatively high amounts of N‐alkyls, O‐alkyls and acetals were present in comparison to earlier published studies, suggesting that large amounts of soil C were potentially vulnerable to microbial degradation. Soil organic matter composition was different at the most southerly site (Dovrefjell, Norway), compared with the two more northerly sites (Abisko, Sweden, and Joatka, Norway), with higher concentrations of aromatics and phenolics, as well as pronounced differences in alkyl concentrations between forest and tundra soils. Clear differences between mountain birch forest and tundra heath soil was noted, with generally higher concentrations of labile carbon present in tundra soils. We conclude that, although mesic soils around the forest‐tundra ecotone in Fennoscandia are a potential source of C to the atmosphere in a changing environment, the response is likely to vary between comparable ecosystems in relation to latitude and continentality as well as soil properties especially soil nitrogen content and pH. 相似文献
16.
The leaf litter is the major source of soil organic matter in natural and many plantation crop ecosystems. Quantity and quality
of organic matter in a soil ecosystem is of utmost importance in regulating the soil health. Hence assessment of quality of
organic matter input, viz., litter is important and is attempted in this study. The leaf litter of rubber (Hevea brasiliensis), pueraria (Pueraria phaseoloides), mucuna (Mucuna bracteata), teak (Tectona grandis) and forest (mixed species) were analyzed using solid state 13C nuclear magnetic resonance (NMR) to study the relative abundance of different carbon compounds present. The spectra revealed
that litter of all species studied contain relatively larger amounts of polysaccharides compared to other C containing compounds.
Also it could be observed that the alkyl-C to O-alkyl-C ratio of rubber litter was much higher compared to that of others.
Aromatics and carbonyl compounds were also present in all litter species. The resource quality based on alkyl-C to O-alkyl-C
ratio of the litter samples studied can be arranged in the order pueraria > teak > mucuna > forest > rubber. The respiration
rate, substrate induced respiration rate and biomass-C (Cmic) of the litter samples were estimated. It could be observed that litter associated microbial activity decreased as alkyl-C
to O-alkyl-C ratio increased. Resource quality derived from the NMR spectra and the litter biological properties were complementary.
Soil samples (0–15 cm) from the five soil ecosystems (rubber, pueraria, mucuna, teak and forest) were analyzed for respiration
rate, substrate induced respiration rate, Cmic, total-C and total-N. The forest soil had higher respiration rate, total-C and total-N compared to cultivated soil systems.
Pueraria, mucuna and teak soils were comparable for their biological properties while rubber soil recorded comparatively lower
microbial activity. 相似文献
17.
Anthropogenic N deposition increases soil organic matter accumulation without altering its biochemical composition 总被引:1,自引:0,他引:1
Donald R. Zak Zachary B. Freedman Rima A. Upchurch Markus Steffens Ingrid Kögel‐Knabner 《Global Change Biology》2017,23(2):933-944
Accumulating evidence indicates that future rates of atmospheric N deposition have the potential to increase soil C storage by reducing the decay of plant litter and soil organic matter (SOM). Although the microbial mechanism underlying this response is not well understood, a decline in decay could alter the amount, as well as biochemical composition of SOM. Here, we used size‐density fractionation and solid‐state 13C‐NMR spectroscopy to explore the extent to which declines in microbial decay in a long‐term (ca. 20 yrs.) N deposition experiment have altered the biochemical composition of forest floor, bulk mineral soil, as well as free and occluded particulate organic matter. Significant amounts of organic matter have accumulated in occluded particulate organic matter (~20%; oPOM); however, experimental N deposition had not altered the abundance of carboxyl, aryl, alkyl, or O/N‐alkyl C in forest floor, bulk mineral soil, or any soil fraction. These observations suggest that biochemically equivalent organic matter has accumulated in oPOM at a greater rate under experimental N deposition, relative to the ambient treatment. Although we do not understand the process by which experimental N deposition has fostered the occlusion of organic matter by mineral soil particles, our results highlight the importance of interactions among the products of microbial decay and the chemical and physical properties of silt and clay particles that occlude organic matter from microbial attack. Because oPOM can reside in soils for decades to centuries, organic matter accumulating under future rates of anthropogenic N deposition could remain in soil for long periods of time. If temperate forest soils in the Northern Hemisphere respond like those in our experiment, then unabated deposition of anthropogenic N from the atmosphere has the potential to foster greater soil C storage, especially in fine‐texture forest soils. 相似文献
18.
Effects of nutrient additions on ecosystem carbon cycle in a Puerto Rican tropical wet forest 总被引:3,自引:0,他引:3
Wet tropical forests play a critical role in global ecosystem carbon (C) cycle, but C allocation and the response of different C pools to nutrient addition in these forests remain poorly understood. We measured soil organic carbon (SOC), litterfall, root biomass, microbial biomass and soil physical and chemical properties in a wet tropical forest from May 1996 to July 1997 following a 7‐year continuous fertilization. We found that although there was no significant difference in total SOC in the top 0–10 cm of the soils between the fertilization plots (5.42±0.18 kg m?2) and the control plots (5.27±0.22 kg m?2), the proportion of the heavy‐fraction organic C in the total SOC was significantly higher in the fertilized plots (59%) than in the control plots (46%) (P<0.05). The annual decomposition rate of fertilized leaf litter was 13% higher than that of the control leaf litter. We also found that fertilization significantly increased microbial biomass (fungi+bacteria) with 952±48 mg kg?1soil in the fertilized plots and 755±37 mg kg?1soil in the control plots. Our results suggest that fertilization in tropical forests may enhance long‐term C sequestration in the soils of tropical wet forests. 相似文献
19.
We investigated the effect of leaf litter on below ground carbon export and soil carbon formation in order to understand how litter diversity affects carbon cycling in forest ecosystems. 13C labeled and unlabeled leaf litter of beech (Fagus sylvatica) and ash (Fraxinus excelsior), characterized by low and high decomposability, were used in a litter exchange experiment in the Hainich National Park (Thuringia, Germany). Litter was added in pure and mixed treatments with either beech or ash labeled with 13C. We collected soil water in 5 cm mineral soil depth below each treatment biweekly and determined dissolved organic carbon (DOC), δ13C values and anion contents. In addition, we measured carbon concentrations and δ13C values in the organic and mineral soil (collected in 1 cm increments) up to 5 cm soil depth at the end of the experiment. Litter-derived C contributes less than 1% to dissolved organic matter (DOM) collected in 5 cm mineral soil depth. Better decomposable ash litter released significantly more (0.50±0.17%) litter carbon than beech litter (0.17±0.07%). All soil layers held in total around 30% of litter-derived carbon, indicating the large retention potential of litter-derived C in the top soil. Interestingly, in mixed (ash and beech litter) treatments we did not find a higher contribution of better decomposable ash-derived carbon in DOM, O horizon or mineral soil. This suggest that the known selective decomposition of better decomposable litter by soil fauna has no or only minor effects on the release and formation of litter-derived DOM and soil organic matter. Overall our experiment showed that 1) litter-derived carbon is of low importance for dissolved organic carbon release and 2) litter of higher decomposability is faster decomposed, but litter diversity does not influence the carbon flow. 相似文献
20.
Spatial heterogeneity of soil respiration and related properties at the plant scale 总被引:17,自引:1,他引:16
Stoyan Helmut De-Polli Helvecio Böhm Sven Robertson G. Philip Paul Eldor A. 《Plant and Soil》2000,222(1-2):203-214
Geostatistical techniques were used to quantify the scale and degree of soil heterogeneity in 2 m2 plots around 9-year-old poplar trees and within a wheat field. Samples were taken during two years, on an unaligned grid,
for analysis of soil respiration, C and N content, available P, gravimetric moisture, pH, nitrification potential, and root
biomass. Kriged maps of soil respiration, moisture, and C content showed strong spatial structure associated with poplar trees
but not with wheat rows. All soil properties showed higher autocorrelation in June than in April. Isopleth patchiness for
all variates was less in June. This was associated with lower respiration rates due to lower litter decomposition. From the
degree and scale of heterogeneity seen in this study, we conclude that the main causes of soil heterogeneity at this scale
(2 m2) are likely to be found at micro scales controlled in part by plant root and plant residue patterns. These must be understood
in the evaluation of ecosystem processes.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献