共查询到20条相似文献,搜索用时 15 毫秒
1.
Outi Priha Susan J. Grayston Risto Hiukka Taina Pennanen A. Smolander 《Biology and Fertility of Soils》2001,33(1):17-24
Microbial biomass C (Cmic), C mineralization rate, phospholipid fatty acid (PLFA) profiles and community level physiological profiles (CLPPs) using
Biolog were determined from the humus and mineral soil layers in adjacent stands of Scots pine (Pinus sylvestris L.), Norway spruce [Picea abies (L.) Karst.] and silver birch (Betula pendula Roth) at two forest sites of different fertility. In addition, the Fourier-transformed infrared (FTIR) spectra were run on
the samples for characterization of the organic matter. Cmic and C mineralization rate tended to be lowest under spruce and highest under birch, at the fertile site in all soil layers
and at the less fertile site in the humus layer. There were also differences in microbial community structure in soils under
different tree species. In the humus layer the PLFAs separated all tree species and in the mineral soil spruce was distinct
from pine and birch. CLPPs did not distinguish microbial communities from the different tree species. The FTIR spectra did
not separate the tree species, but clearly separated the two sites.
Received: 3 December 1999 相似文献
2.
《European Journal of Soil Biology》2008,44(1):1-9
The aim of this study was to explore the response of C and N transformations in the humus layer under silver birch (Betula pendula Roth) to compounds, especially condensed tannins, of different molecular weight extracted and fractioned from Norway spruce (Picea abies (L.) Karst) and Scots pine (Pinus sylvestris L.) needles. Lighter fractions containing tannin monomers and dimers as well as many other compounds, and heavier fractions consisting predominantly of polymerized condensed tannins, were added to samples taken from the humus layer of birch stand. The effects of the spruce and pine fractions were mostly similar, but some differences in magnitude were observed; our results indicated that lighter fractions of pine were easier for microbes to degrade and use than lighter fractions of spruce. Lighter fractions of both tree species increased soil respiration and decreased net N mineralization, while heavier fractions inhibited respiration and increased net N mineralization. Microbial biomass C was not clearly affected by any of the treatments, but with some of the pine fractions the amount of N in the microbial biomass was increased. Comparison of the effects of fractions in birch and in spruce and pine soils, which were studied earlier, showed no major differences between the effects of the fractions in birch and in their own soils, but gave some indication of adaptation. 相似文献
3.
Microbial biomass C and N, and activities related to C and N cycles, were compared in needle and leaf litter, and in the uppermost 10 cm of soil under the litter layer in Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies L.) and silver birch (Betula pendula L.) stands, planted on originally similar field afforestation sites 23–24 years ago. The ground vegetation was differentiated under different tree species, consisting of grasses and herbs under birch and pine, and mosses or no vegetation with a thick layer of needles under spruce. The C:N ratio of the soils was 13–21 and the soil pHCaCl 2 3.8–5.2. Both showed little variation under different tree species. Microbial biomass C and N, C mineralization, net ammonification, reduction) did not differ significantly in soil under different tree species either. Birch leaf litter had a higher pHCaCl 2 (5.9) than spruce and pine needle litter (pH 5.0 and 4.8, respectively). The C:N ratio of spruce needles was 30, and was considerably higher in pine needles (69) and birch leaves (54). Birch leaves tended to have the highest microbial biomass C and C mineralization. Spruce needles appeared to have the highest microbial biomass N and net formation of mineral N, whereas formation of mineral N in pine needles and birch leaves was negligible. Microbial biomass C and N were of the same order of magnitude in the soil and litter samples but C mineralization was tenfold higher in the litter samples. 相似文献
4.
Use of principal component analysis to assess factors controlling net N mineralization in deciduous and coniferous forest soils 总被引:3,自引:0,他引:3
Hilde Vervaet Bernard Massart Pascal Boeckx Oswald Van Cleemput Georges Hofman 《Biology and Fertility of Soils》2002,36(2):93-101
Net N mineralization was studied in three different forest sites (Belgium): a mixed deciduous forest with oak (Quercus robur L. and Quercus rubra L.) and birch (Betula pendula Roth) as dominant species, a deciduous stand of silver birch (Betula pendula) and a coniferous stand of Corsican pine (Pinus nigra ssp. Laricio). The organic (F + H) layer and mineral soil at different depths (0-10, 10-20 and 20-30 cm) were sampled at three locations in the mixed deciduous forest (GE, GF1, GF2), at one location in the silver birch stand (SB) and one in the Corsican pine stand (CP). All samples were incubated over 10 weeks under controlled temperature and moisture conditions. The net N mineralization rates in the organic and upper mineral layer (0-10 cm) were found to be significantly different from the other layers and accounted for 66-95% of the total mineralization over the first 30 cm. Net N mineralization rates in the organic layer ranged from 4.2 to 27.3 mg N m-2 day-1. Net N mineralization and nitrification rates were positively correlated. For the mineral soil, net N mineralization rates decreased with depth and the upper 10 cm showed significantly higher rates, ranging from 8.9 to 33.5 mg N m-2 day-1. The rates of the 10-20 cm and 20-30 cm sublayers were similar, ranging from 1.2 to 7.4 mg N m-2 day-1. The net N mineralization rates for the total mineral layer (0-30 cm) ranged from 17.4 mg N m-2 day-1 (SB) to 36.1 mg N m-2 day-1 (CP). Both from PCA and multiple regression analysis, we could conclude that net N mineralization rates were closely related to the initial mineral N content (Ninitial). Furthermore, significant correlations were observed between the net N mineralization rate, the total carbon (TC) and NH4+-N content for the mineral layers and between net N mineralization rate, total nitrogen (TN), hemicellulose content and C/N for the organic layers. 相似文献
5.
Microbial biomass C and N, and activities related to C and N cycles, were compared in needle and leaf litter, and in the uppermost 10 cm of soil under the litter layer in Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies L.) and silver birch (Betula pendula L.) stands, planted on originally similar field afforestation sites 23–24 years ago. The ground vegetation was differentiated under different tree species, consisting of grasses and herbs under birch and pine, and mosses or no vegetation with a thick layer of needles under spruce. The C:N ratio of the soils was 13–21 and the soil pHCaCl
2 3.8–5.2. Both showed little variation under different tree species. Microbial biomass C and N, C mineralization, net ammonification, reduction) did not differ significantly in soil under different tree species either. Birch leaf litter had a higher pHCaCl
2 (5.9) than spruce and pine needle litter (pH 5.0 and 4.8, respectively). The C:N ratio of spruce needles was 30, and was considerably higher in pine needles (69) and birch leaves (54). Birch leaves tended to have the highest microbial biomass C and C mineralization. Spruce needles appeared to have the highest microbial biomass N and net formation of mineral N, whereas formation of mineral N in pine needles and birch leaves was negligible. Microbial biomass C and N were of the same order of magnitude in the soil and litter samples but C mineralization was tenfold higher in the litter samples. 相似文献
6.
The chemical and microbial properties of afforested mine soils are likely to depend on the species composition of the introduced
vegetation. This study compared the chemical and microbial properties of organic horizons and the uppermost mineral layers
in mine soils under pure pine (Pinus sylvestris), birch (Betula pendula), larch (Larix decidua), alder (Alnus glutinosa), and mixed pine–alder and birch–alder forest stands. The studied properties included soil pH, content of organic C (Corg) and total N (Nt), microbial biomass (Cmic), basal respiration, nitrogen mineralization rate (Min-N), and the activities of dehydrogenase, acid phosphomonoesterase,
and urease. Near-infrared spectroscopy (NIR) was used to detect differences in the chemical composition of soil organic matter
under the studied forest stands. There were significant differences in Corg and Nt contents between stands in both O and mineral soil horizons and also in the chemical composition of the accumulated organic
matter, as indicated by NIR spectra differences. Alder was associated with the largest Corg and Nt accumulation but also with a significant decrease of pH in the mineral soil. Microbial biomass, respiration, the percentage
of Corg present as Cmic, Min-N, and dehydrogenase activity were the highest under the birch stand, indicating a positive effect of birch on soil
microflora. Admixture of alder to coniferous stand increased basal respiration, Min-N, and activities of dehydrogenase and
acid phosphomonoesterase as compared with the pure pine stand. In the O horizon, soil pH and Nt content had the most important effects on all microbial properties. In this horizon, the activities of urease and acid phosphomonoesterase
did not depend on microbial biomass. In the mineral layer, however, the amount of accumulated C and microbial biomass were
of primary importance for the enzyme activities. 相似文献
7.
The aim of this study was to determine whether tree species consistently affects soil microbial activities related to C and N cycling and to compare these activities with the characteristics of soil dissolved organic matter (DOM). Samples were taken from the mor-type organic layer (Of+Oh) underlain by podzols of six 20–72-year-old tree-species experiments on different site types in different parts of Finland. Sampling plots were dominated by silver birch (Betula pendula Roth), Norway spruce (Picea abies (L.) Karst) or Scots pine (Pinus sylvestris L., only on four sites). Amounts of C and N in the microbial biomass and rates of C mineralization (CO2 production) and net N mineralization were determined, and water extracts were analysed for concentrations of DOC and DON and characterized according to molecular size by ultrafiltration and according to chemical composition using a resin fractionation technique. In all older stands, birch, compared to spruce or pine, increased soil pH, NH4-concentration and amounts of C and N in microbial biomass and decreased the C-to-N ratio and ratio of dissolved organic N (DON)-to-mineral N. Birch had similar effects also in part of the younger stands. Birch also increased the rates of both C and net N mineralization compared to spruce or pine but only on two sites. In all soils, net nitrification was low. The distribution of DOC into different fractions based on chemical composition and molecular size was rather similar in all soils. The most abundant chemical fraction was hydrophobic acids, and the most abundant molecular size fraction was 10–100 kDa. The C-to-N ratio varied but was lowest in hydrophilic bases and in the smallest molecular size class. Mineralization of C was highly and positively correlated with concentration of DOC (Pearson's correlation coefficient r = 0.9, P < 0.01). The results indicated close interactions between microbial processes and dissolved organic matter. 相似文献
8.
Volatile monoterpenes in soil atmosphere under birch and conifers: Effects on soil N transformations
The aim of this study was to examine the occurrence and concentrations of volatile organic compounds (VOCs), in particular, volatile monoterpenes, in soil atmosphere under silver birch (Betula pendula L.) and two conifers, Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.), and to determine the effects of the most relevant monoterpenes on transformations of soil N. The study site was a 70-year-old tree species experiment in Kivalo, northern Finland. VOCs were collected using two methods, passive air samplers and a chamber method. In soil atmosphere under spruce and especially under pine, the concentrations of monoterpenes were high, α- and β-pinene, Δ-3-carene and myrcene being the most abundant compounds, whereas concentrations of monoterpenes in soil atmosphere under birch were negligible. Samples of humus layer from the birch stand incubated in vitro and exposed to vapors from monoterpenes typical of coniferous forest soil showed decreased rates of net N mineralization but simultaneously increased rates of C mineralization. The response of soil microbial biomass C and N to different monoterpenes varied, but some monoterpenes considerably decreased soil microbial biomass. Altogether these results suggest that these compounds have negative effects on soil N transformations, but may serve as carbon and energy source for part of soil microbes. 相似文献
9.
Microbial enzyme activities in leaf litter, humus and mineral soil layers of European forests 总被引:2,自引:0,他引:2
The rationale of the study was to investigate microbial activity in different soil horizons in European forests. Hence, activities of chitinase and cellulase, microbial biomass carbon (Cmic) and basal respiration were measured in litter, fragmentation, humus and mineral soil layers collected several times from various beech and spruce forests. Sites were selected to form a gradient in N availability. Analyses were also performed on beech litter from a litterbag transplant experiment. Furthermore, microbiological parameters were measured in horizons of beech and spruce chronosequence sites with different stand age in order to investigate the influence of forest rotation, and hence changes in soil organic matter (SOM) dynamics, on microbial activity. Finally in horizons of one beech forest, the seasonal variation of selected microbiological parameters was measured more intensively. β-Glucosaminidase and cellobiohydrolase activities were measured using fluorogenic 4-methylumbelliferyl substrates to estimate chitinase and cellulase activities, respectively. On a spatial scale, chitinase and cellulase activities, Cmic determined by substrate induced respiration, and basal respiration ranged from 144 to 1924 and 6-177 nmol 4-MU g−1 org-C h−1, 8-48 mg C g−1 org-C and 11-149 μg CO2-C g−1 org-C h−1, respectively; in general values were significantly lower in layers of humus and mineral soil than of litter. Chitinase activity, Cmic and basal respiration from humus and mineral soil layers, together, correlated positively, while none correlated with cellulase activity. Similarly in the litter layer, no correlations were found between the microbiological parameters. On a seasonal scale, a time lag between a burst in basal respiration rate and activities of both enzymes were observed. In general, activities of cellulase and chitinase, Cmic and basal respiration, did not change with stand age, except in the humus layer in the spruce chronosequence, where Cmic decreased with stand age. In the litter layer, cellulase activity was significantly and positively related to the C:N ratio, while only a tendency for chitinase activity was shown, indicating that enzyme activities decreased with increasing N availability. In accordance, the enzyme activities and Cmic decreased significantly with increasing chronic N deposition in the humus layer, while basal respiration only tended to decrease with increasing N deposition. In contrast, enzyme activities in beech litter from litterbags after 2 years of incubation were generally higher at sites with higher N deposition. The results show different layer-specific responses of enzyme activities to changes in N availability, indicating different impacts of N availability on decomposition of SOM and stage of litter decomposition. 相似文献
10.
The purpose of this study was to examine the effects of the resin volatile compounds of two coniferous tree species, Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) on C and N transformations in soil under silver birch (Betula pendula L.). Humus layers from two study sites were used, referred here as a N-poor soil (C:N ratio 30) and a N-rich soil (C:N ratio 19.5). In addition to these, N-poor soil added with arginine was used to ensure that the soil was not N-limited. Humus layers were subjected to resin treatments during a 28-day incubation period in the laboratory. The most abundant volatile compound in both resins was α-pinene; in spruce resin β-pinene was also abundant. Resins and pure α-pinene increased CO2-C production, i.e. C mineralization, in both soils. In contrast, net N mineralization was clearly decreased in both soils, and net nitrification was completely stopped. There was no consistent effect on soil microbial biomass C or N. Based on these results, we conclude that volatile resin compounds affect C and N transformations in soil, but the mechanism behind these effects is still unclear. 相似文献
11.
The aim of this study was to compare the effects of silver birch (Betula pendula Roth) and Norway spruce (Picea abies (L.) Karst.) on soil C and N transformations and on the characteristics of organic matter. Soil samples were taken from the humus layer of a replicated 35-year-old birch-spruce field experiment growing on Vaccinium myrtillus site type in middle-eastern Finland. The soil was a podzol and humus type mor. Soil pH was higher under birch (4.7) than under spruce (4.1). The C-to-N ratio was lower under birch (17) than under spruce (23). Per unit organic matter, microbial biomass C and N, net N mineralization and net nitrification were all higher in birch soil than in spruce soil. The rate of C mineralization (CO2 production) was, however, the same regardless of tree species. Water-extracts were analyzed for the concentrations of dissolved organic C (DOC) and N (DON) and characterized according to molecular size distribution by ultrafiltration and according to chemical composition using a resin fractionation technique. The concentration of DON, in particular, was higher in birch soil than in spruce soil. The distribution of DOC and DON into different fractions based on molecular size or chemical composition was rather similar in both soils. The concentration of total phenolics, expressed as tannic acid equivalents, was higher in the humus layer under birch than in the humus layer under spruce, because the birch humus layer contained significantly more low-molecular weight (about <0.5 kD) phenolics than the spruce humus layer did. The concentration of proanthocyanidins (condensed tannins) was higher in spruce soil than in birch soil. The concentrations of the five most abundant phenolic acids showed that ferulic and p-coumaric acids were more abundant in spruce soil. Birch soil tended to contain slightly more nonvolatile sesquiterpenes than the spruce soil. The concentration of diterpenes was similar in both soils; but birch soil contained significantly more triterpenes, mainly sterols, than spruce soil did. 相似文献
12.
《Soil biology & biochemistry》1986,18(1):45-51
Samples of strongly acid forest litter and humus from beneath Sitka spruce, heather, Scots pine and larch from two sites in north-east Scotland were incubated aerobically at 20°C in the laboratory. At the Glen Tanar site, spruce litter and larch humus showed significant nitrification and ammonification whereas spruce humus and Scots pine humus produced only NH4+-N. Heather humus showed no net mineralization. At the Fetteresso site, application of fertilizer N, P and K to Sitka spruce up to 3 yr previously, significantly stimulated the production of NO3−-N in both litter and humus.Amendment of the samples with organic N as peptone caused significant increases in NO3−-N production in those samples that already showed nitrification. The increases in NO3−-N generally represented a low proportion of the added peptone-N. Amendment with NH4+-N as (NH4)2SO4 either had no effect or significantly reduced NO3−-N production (in larch humus). The results suggest the occurrence of heterotrophic nitrification in some of these forest samples.Net immobilization of NH4+-N was typically greater in NH4+-N amended than in peptone amended samples, except for heather humus which showed complete immobilization of both N sources.Total mineral N produced at the end of the aerobic incubation was correlated (P < 0.01) with NH4+-N produced during a 30-day anaerobic incubation at 30°C. Net NO3−-N production was greater in litter than in the corresponding humus samples and was correlated (P < 0.001) with initial organic N soluble in 1 m KCl. 相似文献
13.
A. C. Campos J. B. Etchevers K. L. Oleschko C. M. Hidalgo 《Land Degradation \u0026amp; Development》2014,25(6):581-593
A study was conducted to examine the responses of microbial activity and nitrogen (N) transformations along an altitudinal gradient. The gradient was divided into three parts. Three areas were sampled: upper part (UP): coniferous forest, corn field, and abandoned corn field; middle part (MP): tropical cloud forest, grassland, and corn field (COL); and lower part (LP): tropical deciduous forest and sugarcane. The results showed that soil microbial biomass carbon (C) and basal respiration were significantly higher in MP and UP than in LP, whereas the microbial quotient (Cmic/Corg) was higher in LP and MP than in UP. The metabolic quotient (qCO2) was similar among gradient parts evaluated. Net N mineralization, ammonification, and nitrification rates were higher in UP than MP and LP. We found that in UP, the forest conversion to cropland resulted in no significant differences in microbial activity and N transformation rates between land uses. In MP, microbial biomass C, ammonification, and net N mineralization rates decreased significantly with conversion to cropland, but Cmic/Corg and nitrification were higher in COL. Basal respiration and qCO2 were significantly lower in COL when compared with other land uses. In LP, lower microbial biomass C, Cmic/Corg, and nitrification rates but higher ammonification and net N mineralization rates were observed in tropical deciduous forest than in sugarcane. No significant differences in basal respiration and qCO2 were found between uses of LP. Clearly, then, soil organic C is not equally accessible to the microbial community along the gradient studied. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
14.
To evaluate the validity of different indices in estimating soil readily mineralizable N, soil microbial biomass (Nmic), soil active N (SAN), soluble organic N (SON), net N mineralization rate (NNR) and gross N mineralization rate (GNR) in mineral soils (0-10 cm) from six forest stands located in central Germany were determined and compared with two sampling times: April and November. Additionally, soil density fractionation was conducted for incubated soils (with addition of ^15NH4-N and glucose, 40 days) to observe the sink of added ^15N in different soil fractions. The study showed that Nmic and NNR in most stands differed significantly (P 〈 0.05) between the two sampling times, but not GNR, SAN and SON. In November, no close relationships were found between GNR and other N indices, or between Nrnic, SON, and SAN and forest type. However, in April, GNR was significantly correlated (P 〈 0.05) with Nmic, SAN, and NNR along with Nmlc under beech being significantly higher (P 〈 0.05) than under conifers. Furthermore, density fractionation revealed that the light fraction (LF, 0.063-2 mm, 〉 1.7 gcm^-3) was not correlated with the other N indices. In contrast, results from the incubation study proved that more 15N was incorporated into the heavy fraction (HF 〈 0.063 ram, 〉 1.7 g cm^-3) than into LF, indicaing that more labile N existed in HF than in LF. These findings suggested that attention should be paid to the differences existing in N status between agricultural and forest soils. 相似文献
15.
A field study was conducted during the summer of 1995 to gain abetter understanding of the causes of nitrate (NO3-N)leaching and ongoing changes in soil nitrogen (N) availabilityin high-elevation (1524–2000 m) spruce (Picea rubens) andfir (Abies fraseri) forests of the Great Smoky MountainsNational Park, Tennessee and North Carolina, U.S.A. Indicatorsof soil N availability (total soil N concentrations,extractable NH4-N, extractable NO3-N, and C/N ratios)were measured in Oa and A horizons at 33 study plots. Dynamicmeasures included potential net soil N mineralization determinedin 12-week aerobic laboratory incubations at 22 °C.Potential net nitrification in the A horizon was correlated (r =+0.83, P < 0.001) with total soil N concentrations. Mostmeasures of soil N availability did not exhibit significanttrends with elevation, but there were topographic differences.Potential net soil N mineralization and net nitrification in theA horizon were higher in coves than on ridges. Relative amountsof particulate and organomineral soil organic matter influencedpotential net N mineralization and nitrification in the Ahorizon. Calculations indicate that soil N availability andNO3-N leaching in high-elevation spruce and fir forests ofthe Great Smoky Mountains National Park will increase inresponse to regional warming. 相似文献
16.
Tannins are polyphenolic compounds that may influence litter decomposition, humus formation, nutrient (especially N) cycling and ultimately, plant nutrition and growth. The aim of this study was to determine the response of C and N transformations in soil to tannins of different molecular weight from Norway spruce (Picea abies (L.) Karst) and Scots pine (Pinus sylvestris L.) needles, tannic acid and cellulose. Arginine was added to test whether the soil microbial community was limited by the amount of N, and arginine+tannin treatments were used to test whether the effects of tannins could be counteracted by adding N. Soil and needle samples were taken from adjacent 70-year-old Scots pine and Norway spruce stands located in Kivalo, northern Finland. Tannins were extracted from needles and fractioned based on molecular weight; the fractions were then characterized by LC-MS and GC-MS. Light fractions contained tannin monomers and dimers as well as many other compounds, whereas heavy fractions consisted predominantly of polymerized condensed tannins. Spruce needles contained more procyanidin than prodelphinidin units, while in pine needles prodelphinidin units seemed to be dominant. The fractions were added to soil samples, pine fractions to pine soil and spruce fractions to spruce soil, and incubated at 14 °C for 6 weeks. CO2 evolution was followed throughout the experiment, and the rates of net mineralization of N and net nitrification, concentration of dissolved organic N (DON) and amounts of microbial biomass C and N were measured at the end of the experiment. The main effects of the fractions were similar in both soils. Light fractions strongly enhanced respiration and decreased net N mineralization, indicating higher immobilization of N in the microbial biomass. On the contrary, heavy fractions reduced respiration and slightly increased net N mineralization, suggesting toxic or protein-precipitating effects. The effects of tannic acid and cellulose resembled those of light fractions. DON concentrations generally decreased during incubation and were lower with heavy fractions than with light fractions. No clear differences were detected between the effects of light and heavy fractions on microbial biomass C and N. Treatments that included addition of arginine generally showed trends similar to treatments without it, although some differences between light and heavy fractions became more obvious with arginine than without it. Overall, light fractions seemed to act as a labile source of C for microbes, while heavy fractions were inhibitors. 相似文献
17.
The relationships of soil microbial biomass C (Cmic) or N (Nmic) with mean annual precipitation and temperature were studied along a climatic transect in the Mongolian steppe. Soil organic C (Corg) and total N (Nt), respiration rate, Cmic and Nmic at depths of 0–5 and 5–10 cm decreased with increasing aridity. The contents of Corg and Nt in the 0- to 5-cm soil layers decreased linearly with precipitation reduction along the transect. Cmic and Nmic changes with precipitation were not linear, with higher changes between 330 and 128 mm mean annual precipitation. Cmic/Corg and Nmic/Nt increased with increasing aridity. The metabolic quotient qCO2 of 0- to 5-cm soil layers was low between 330 and 273 mm precipitation. The relationship between the qCO2 of the 0- to 5-cm soil layers and the mean annual precipitation was well fitted with a quadratic function y =0.0006x2 –0.40x +86.0, where y is the qCO2 (µmol CO2-C mmol–1 Cmic) and x is the mean annual precipitation (mm). Corg, Nt, Cmic, Nmic and respiration rate decreased exponentially with increasing mean annual temperature in both the 0- to 5- and 5- to 10-cm soil layers, and change rate was lower when the mean annual temperature was higher than 2.6°C. The close relationships of the mean annual precipitation or temperature with soil Corg, Nt, Cmic, Nmic, Cmic/Corg and qCO2 indicate that each parameter can be calculated by determining the other parameters in this specific climatic range. 相似文献
18.
I. Yu. Kudrevatykh K. V. Ivashchenko N. D. Ananyeva E. A. Ivanishcheva 《Eurasian Soil Science》2018,51(2):153-162
Twenty plots (20 m2 each) were selected in coniferous and mixed forests of the industrial Vologda district and the Vytegra district without developed industries in Vologda region. In March, snow cores corresponding to the snow cover depth were taken on these plots. In August, soil samples from the 0- to 20-cm layer of litter-free soddy-podzolic soil (Albic Retisol (Ochric)) were taken on the same plots in August. The content of mineral nitrogen (Nmin), including its ammonium (NH+4) and nitrate (NO-3) forms, was determined in the snow (meltwater) and soil. The contents of total organic carbon, total nitrogen, and elements (Al, Ca); pH; particle size distribution; and microbiological parameters―carbon of microbial biomass (Cmic) and microbial respiration (MR)―were determined in the soil. The ratio MR/Cmic = qCO2 (specific respiration of microbial biomass, or soil microbial metabolic quotient) was calculated. The content of Nmic in meltwater of two districts was 1.7 mg/L on the average (1.5 and 0.3 mg/L for the NH+4 and NO–3 forms, respectively). The annual atmospheric deposition was 0.6–8.9 kg Nmin/ha, the value of which in the Vologda district was higher than in the Vytegra district by 40%. Reliable correlations were found between atmospheric NH+4 depositions and Cmic (–0.45), between NH+4 and qCO2 (0.56), between atmospheric NO-3 depositions and the soil NO-3 (–0.45), and between NO-3 and qCO2 (–0.58). The content of atmospheric Nmin depositions correlated with the ratios C/N (–0.46) and Al/Ca (–0.52) in the soil. In forests with the high input of atmospheric nitrogen (>2.0 kg NH+4/(ha yr) and >6.4 kg Nmin/(ha yr)), a tendency of decreasing Cmic, C/N, and Al/Ca, as well as increasing qCO2, was revealed, which could be indicative of deterioration in the functioning of microbial community and the chemical properties of the soil. 相似文献
19.
Successional changes in microbial biomass,respiration and nutrient status during litter decomposition in an aspen and pine forest 总被引:5,自引:0,他引:5
Microbial biomass, microbial respiration, metabolic quotient (qCO2), Cmic/Corg ratio and nutrient status of the microflora was investigated in different layers of an aspen (Populus tremuloides Michx.) and pine forest (Pinus contorta Loud.) in southwest Alberta, Canada. Changes in these parameters with soil depth were assumed to reflect successional changes in aging litter materials. The microbial nutrient status was investigated by analysing the respiratory response of glucose and nutrient (N and P) supplemented microorganisms. A strong decline in qCO2 with soil depth indicated a more efficient C use by microorganisms in later stages of decay in both forests. Cmic/Corg ratio also declined in the aspen forest with soil depth but in the pine forest it was at a maximum in the mineral soil layer. Microbial nutrient status in aspen leaf litter and pine needle litter indicated N limitation or high N demand, but changes in microbial nutrient status with soil depth differed strongly between both forests. In the aspen forest N deficiency appeared to decline in later stages of decay whereas P deficiency increased. In contrast, in the pine forest microbial growth was restricted mainly by N availability in each of the layers. Analysis of the respiratory response of CNP-supplemented microorganisms indicated that growth ability of microorganisms is related to the fungal-bacterial ratio. 相似文献
20.
The correlation of soil temperature and moisture with inorganic N concentrations and net mineralization beneath major species types in mature boreal and northern hardwood forests was examined over a two year period. Soils beneath species types where the canopy was dominated byBetula papyrifera, Picea glauca, Alnus rugosa or, in northern hardwoods,Acer saccharum were studied. Net NO3 ? mineralization varied by species type and net total inorganic nitrogen (N) mineralization varied by month and the interaction of species type with month. Soil NO3 ? concentration and NO3 ? mineralization were correlated for spruce, and inversely correlated for alder and maple. Soil NH4 + concentration and NH4 + mineralization were inversely correlated for alder and maple. In laboratory temperature and moisture treatments of birch, spruce and maple soils, NH4 + and total inorganic N-mineralization increased with temperature. The response to moisture was most evident for NO3 ? mineralization in maple soils. 相似文献