Arbuscular mycorrhizal fungi enhance soil carbon sequestration in the coalfields, northwest China
Arbuscular mycorrhizal fungi enhance soil carbon sequestration in the coalfields, northwest China
OPEN Carbon storage is affected by photosynthesis (Pn) and soil respiration (Rs), which have been studied extensively in natural and agricultural systems. However, the effects of Pn and Rs on carbon storages in the presence of arbuscular mycorrhizal fungi (AMF) in coalfields remain unclear. A field experiment was established in 2014 in Shendong coal mining subsidence area. The treatments comprised two inoculation levels (inoculated with or without 100 g AMF inoculums per seedlings) and four plant species [wild cherry (Prunus discadenia Koebne L.), cerasus humilis (Prunus dictyneura Diels L.), shiny leafYellow horn (Xanthoceras sorbifolium Bunge L.) and apricot (Armeniaca sibirica L.)]. AMF increased Pn of four species ranging from 15.3% to 33.1% and carbon storage, averaged by 17.2% compared to controls. Soil organic carbon (OC), easily extractable glomalin-relation soil protein (EE-GRSP), and total glomalinrelation soil protein (T-GRSP) were significantly increased by AMF treatment. The effect of AMF on the sensitivity of Rs depended on soil temperature. The results highlighted the exponential models to explain the responses of Rs to soil temperature, and for the first time quantified AMF caused carbon sequestration and Rs. Thus, to our knowledge, AMF is beneficial to ecosystems through facilitating carbon conservation in coalfield soils.
Carbon storage depends on the balance between carbon sequestration by plant Pn and carbon release to
atmosphere through Rs1,2. Therefore, if plant Pn or Rs is altered, carbon balance will be affected. Rs, especially seasonal
variations, are significantly affected by soil temperature and moisure3,4. However, the impact of soil microbes on
Rs or carbon storage remains unclear. So far, quantified contribution of soil microbes, especially AMF has not
been reported yet. AMF are obligate plant symbionts that associates with the roots of more than 80% vascular
land plants, which significantly enhance long-term success of mine site reclamation5. Studies showed that AMF
are helpful for building up a productive, healthy, and sustainable post-mine land ecosystem with vegetation cover.
The positive impact of AMF on reclaimed soil fertility and plant communities succession has been well
documented6?8. However, few studies focused on the effects of AMF on Rs in post-mine land. A recent study conducted
in Germany grassland communities reported that AMF stimulated Rs on pasture soil, leading to elevated CO2
level and temperature, with most carbon sequestered in belowground parts, making Rs an important component
of carbon balance9,10. Factors such as soil moisture, soil temperature, CO2 enrichment, and precipitation changes
were all affected Rs. However, relevant studies remain scare and the complexity of various interactions that affect
Rs (such as soil temperature vs moisture, soil temperature vs microbes, moisture vs microbes interactions) are still
Rs includes intergated CO2 flux of root respiration, mycorrhizal respiration (considered as part of autotrophic
respiration), and heterotrophic respiration, which are controlled by carbon supply and temperature9,10. Carbon
supply is an important Rs impact factor, which primarily depends on plant productivity and generally responds
positively to CO2 enrichment with the increased Pn11. Numerous studies confirmed that carbon storage depended
on plant Pn and Rs via AMF in greenhouse or field experiments7,9?11.
AMF usually form symbiotic associations with trees in diverse forests. The fungi rely on host plant to obtain
carbon supply and utilize 5?20% of the net photosynthate of the symbiotic system11. Global forest soil releases
24 Pg Carbon per year into atmosphere via CO2 efflux and generates CO2 from a widely variety of belowground
organisms, with AMF as the dominant carbon source12. AMF as an important carbon and soil CO2 efflux source
have been well studied under various temperature and moisture conditions12. A pulse-labeling experiment
showed that in temperate prairie, about 4?6% photoassimilates were facilitated via AMF10. Simultaneously, AMF
enhanced 16% soil CO2 efflux when Lolium pernne roots were colonized and 8% carbon supply was derived from
AMF in a barley field13. To date, no studies have been carried out on the contribution of AMF on carbon storage
in coal mining soil.
Respiratory quotient (Q10) is defined as the temperature sensitivity of Rs which is derived from substrate
availability, which is the respiration variation ratio when soil temperature rises 10 ?C. Q10 is largely affected by
a series of environmental factors, such as soil physicochemical properties and soil moisture, etc. However, few
studies have quantified the effects of AMF on apparent Q10 from different tree species. Thus, knowledge about the
function of AMF on Rs, Pn, and carbon storage is insufficient14.
Notably, CO2 concentration indirectly influences Rs and carbon allocation from host species to fungus,
suggesting that root participates in carbon fixation15?17. Most colonized plants enhanced productivity or nutritional
status of the plant symbioses system when exposed to higher CO2 concentration18. In addition, mycorrhizal
hyphae assisted carbon re-distribution from aboveground parts to roots via utilizing the photosynthate and
provides multiple adherent agents such as extracellular polymer, and amino acid, etc than non-colonized plants19.
Briefly, AMF enhance soil carbon proportion in higher CO2 environment20?22. However, lacking a better
understanding of these responses in coal mining soil limited to prediction soil carbon storage when AMF existed in
Thus, the experiment planted wild cherry, cerasus humilis, shiny leaf Yellowh orn and apricot in coal mining
soil and half seedlings were inoculated with AMF inoculums. Based on the experimental results, two hypotheses
was proposed that: (i) plant species preferentially facilitate their photosynthetic ability and increase Rs rates,
leading to different carbon storage amount; and (ii) soil temperature rather than soil moisture is sensitive to Rs
due to the extreme drought. The future goal is to investigate the effect of AMF on carbon sequestration in coal
Pn and Rs temporal dynamics. Pn was significantly greater with AMF inoculation in all the four species
from July to September (Fig.?1). Specifically, AMF treatment increased Pn in wild cherry, cerasus humilis, shiny
leaf Yellowh orn, and apricot by 21.2%, 15.0%, 53.1%, and 7.4%, respectively. Meanwhile, Pn in all four tree species
increased from July to August and then strikingly decreased from August to September (Fig.?1).
In all tree species, Rs was significantly decreased from July to September, with slight decrease from July to
August and reduced sudden reduction of 21.3?26.9% in September (Fig.?2).
Cumulative carbon measures. Annual cumulative carbon in AMF treated wild cherry, cerasus humilis,
shiny leaf Yellowh orn, and apricot were about 1706, 1784, 2049 and 2065 g C.m?2.yr?1 (Fig.?3a?d). Compared to
the corresponding controls, the annual cumulative carbon levels in the four tree species were increased by 28.3%,
44.6%, 31.8% and 33.5%, respectively (Fig.?3a?d). In growing season, AMF increased the carbon storage by 29.4%,
45.7%, 32.4% and 34.4% (P < 0.0001) (Fig.?3a?d). AMF also significantly increased the annual cumulative Rs
carbon in the four tree species by 32.4%, 36.6%, 25.2% and 29.9%, when compared to the corresponding controls
(P < 0.0001) (Fig.?4a?d).
Soil temperature sensitivity to Rs. Rs was calculated using exponential function (Eq.?1), temperature
dynamic showed over 70% Rs variation in AMF treated groups and the correlation of Rs showed only 40%
variation in control groups (Table?1). Apparent Q10 and the coefficient b were decreased significantly in control
apricot and wild cherry (P < 0.05) (Table?1; Fig.?5a,d). However, AMF decreased previous two parameters
in cerasus humilis and shiny leaf Yellowh orn (Fig.?5b,c). Apparent Q10 responded differently to temperature
(the precipitation in 2014 was higher than 10 year?s average precipitation) in August from that in July or
Effects of AMF inoculation on carbon-linked parameters. In control of wild cherry, cerasus humilis,
shiny leaf yellowh orn, and apricot, the production of OC, EE-GRSP and T-GRSP almost did not change with
time (Table?2). In contrast, the production of soil OC, EE-GRSP and T-GRSP in AMF treated of four species
increased significantly over time (Table?2). After three months of treatment, the increment of OC, EE-GRSP and
T-GRSP in AMF treated groups were all significant (27?37%, 34?45% and 19?22%, respectively (Table?2). After
five months of AMF treatments, compared to the control, the levels of OC, EE-GRSP and T-GRSP in AMF treated
groups were remarkable enhanced by 52?61%, 55?70% and 36?44%, respectively (Table?2). Collectively, AMF
had a positively impacted on soil carbon-linked parameters over time in all of the four tree species (Table?2).
The present study firstly examined photosynthetic ability, Rs and carbon storage in respond to AMF inoculation
in the coalfields. Under AMF treatment, carbon storage was derived from belowground parts of the tree species.
Meanwhile, the temporal variability strongly responded to Rs and annual cumulative carbon with exponential
Pn and Rs responses to AMF inoculation. AMF inoculation incurred a series changes in Pn, Rs and
carbon storage via close symbiosis with host plants, leading to enhanced carbon production and improved nutrition
status against the detrimental effects14,23?27. Meanwhile, AMF accelerated the organic matter (OM) decomposition
rates28 and provided some raw materials, which elevated CO2 concentration in micro circumstance29,30 and
facilitated soil carbon turnover in the agro-or grassland via CO2 stimulation effects31. In the moist forest, abundant
and diverse AMF (e.g. tropical forests) species created a transient carbon sink via N transferring to reduce carbon
lost. This implied that AMF promotes carbon production and storage via increasing Pn, which ameliorated the
negative effect caused by unfavorable environment32. Recently, strong evidences showed that the colonized plants
have higher Pn and ribulose-1,5-bisphosphate carboxylase/oxygenase activity than non-colonized plants, which
compensated greater photosynthate33,34. Carbon was produced directly from Pn, and AMF perhaps supported the
higher metabolism of plants and greater productivity of carbon in the harsh environment35?39. Furthermore, soil
temperature decreasing inhibited substrate movement, lowing microbal activity, which decreased plant Pn and
belowground carbon allocation. Temperature also reduced Pn and the belowground coupling, which potentially
affected the substrate availability and carbon cycling40. The results demonstrated that AMF can increase Pn of the
plant, thus increasing carbon allocation.
Carbon partitioning responses to AMF inocluation. Due to its ability to enhance carbon allocation,
AMF has been used in agricultural field and grasslands, but information about carbon storage is omitted in
mining soil. Carbon accumulation tended to be higher with AMF inoculation in this study in the growing season.
AMF sequestered greater carbon via enhanced Pn and photosynthate production, which was transferred from
aboveground to roots or microbes. AMF counteracted carbon loss of respiration, due to increase productivity
and nutrient acquisition, especially carbon sequestration35,41. In the non-growing seasons, AMF perferentially
allocated photosynthate from tree branchs to belowground parts, increasing the EE-GRSP and T-GRSP of
carbon stocks14,38. Estimately, AMF utilized a large proporation (about 20%) of photosynthates19,42?45, leading to
more carbon retention via symbiosis46?50. Consequently, AMF inoculation resulted in remarkable greater carbon
Nonlinear response to Rs. AMF affected carbon storage and partition, which has been discussed in the
previous study51. However, no data have shown whether interactions between species and temperature affect AMF
facilitated carbon sequestration52. As literatures indicated, carbon productivity of the plants was greater with
AMF, due to higher availability of nutrients from the soil environments53. The beneficial effect of AMF in carbon
sequsteration was considered a result of improved availability of nutrients and altered carbon allocation caused
by AMF54?55. The exponential models successfully illustrated the changes of Rs in response to soil temperature
variation and captured monthly dynamics of all tree species used in the exepriment.
Hysteresis between Rs and soil temperature exists in various ecosystems and vegetations56?57. In general,
the decoupling of Rs in response to soil temperature is attributed to confound effect, such as precipitation or
physiological drought caused hysteresis, which leads to decreased AMF activity and subsequently lower CO2
production57. Over all, the Rs-temperature relationship was affected by Pn, litterfall, and soil microbe activities58?61.
However, the detailed mechanisms remain unclear. In this study, due to the existence of hystersis, Rs in
control groups was higher than AMF inoculation groups under a given temperature, which was in agreement with
the previous hypothesis62. Most likely, AMF plants accumulated more fresh litter in a given temperature than
non-colonized plants. Q10 was often used to represent the temperature measurement depth in greenhouse or
field exprimental models14,63. In this work, apparent Q10 increased in AMF treated groups, indicating that AMF
increases the sensitivity of Rs to soil temperature. Apparent Q10 value was lower in summer than in cooler season,
which might be because of higher substrate availability and severe soil moisture limitation in summer. In
consistent with the previous publication14, the experiment data showed that Rs strongly depends on soil temperature in
Previous studies have used exponential model but ingored the function of AMF64. The results suggested that
AMF plays a key role in Rs and carbon stocks. AMF and soil temperature in combination modulate apparent Q10
This study provided new insights into the impacts of AMF on Rs, and carbon storage in coalfields. AMF enhances
carbon sequestration and the sensitivity of Rs to temperature. Higher AMF infection rate significantly enhances
Rs and Pn, the positive AMF function is through promoting plant growth, especially increasing leaf area,
chlorophyll content, and the Q10 value. These results clearly demonstrated that AMF infection increased organic matter
and glomalin which may be associated with the enhancement of carbon storage in soil. The model of Rs to soil
temperature should be reassessed to take into account of the interaction between the soil volumetric moisture
and mycorrhizal fungus. Thus, further study will focus on long-term AMF effect on carbon stock in a tree species
Materials and Methods
Study site and experimental set-up. This experiment was conducted at the ecological reclaimed region,
which located in Daliuta town (39?18?N, 110?4?E), Shenmu County, Yulin City, Shaanxi Province, Northwest
China at 1,200 m height above sea level. This site was a typical junction area of Shanxi, Shaanxi and Inner
Mongolia of three Provinces and the south margin of Mu us desert in the loess plateau transition zone. About 70%
precipitation falls from June to September, the 10-year (200
) average total precipitation and the potential
evaporation were about 150 mm and 2000 mm according to Shenmu Meteorological Station near the experiment
site. The experimental location had a typical characteristic of continental climate, with annual average
temperature about 8?C. The cumulative temperature above 0?C and 10 ?C were 3,550 ?C and 3,210 ?C, respectively; the
frost-free period is 150 days and total solar radiation is 6,000 MJ m?2 year?1. The local soil was classified as
Aeolian sandy (FAO/UNESCO, 1988) which contained 75% sand, 22% silt, and 3% clay. The topsoil
physicochemical properties were: soil OM 4.5 g kg?1, total N 0.21 g kg?1, Olsen P 5.3 mg kg?1, exchangeable K 37.8 mg
kg?1 and pH value (1:2.5 soil: distilled water) 7.9.
All experiments were carried out in three replicates. The sub-plots of four tree species, wild cherry (Prunus
discadenia Koebne L.), cerasus humilis (Prunus dictyneura Diels L.), shiny leaf Yellow horn (Xanthoceras
sorbifolium Bunge L.), and apricot (Armeniaca sibirica L.) were used in the experiments. Each species was divided into
two groups: AMF group and control group. AMF group received the inoculation of AMF at 100 g inoculums/
seedling, while the control group did not contain any AMF inoculums.
The four seedlings were obtained from the forest bureau of Shenmu County, Yulin City, Shaanxi Province and
Northwest China. Each seedling was transplanted into the plot at temperatures ranging from about 10?15 ?C in
. The AMF colonization rate of wild cherry, cerasus humilis, shiny leaf Yellow
horn, and apricot were 4.8%, 6.3%, 5.4%, and 7.2% before transplanting and 78.1%, 80.2%, 76.4%, and 81.7% at
the end of monitoring stage. Two months after transplantation, over 90% of the seedlings were colonized with
Each plot had an area of 20 ? 12 m2, which consisted of 6 rows, with 10 seedlings per row at 2 m row spacing.
100 g AMF was inoculated in root of AMF plants at seedling transplantation. Funneliformis mosseae BGCXJ01
inoculums (Supplied by Beijing Academy of Agriculture and Forestry Sciences) were propagated on Trifolium
repens (clover) for 12 weeks. 100 g inoculums included spores (10?20 spores/g), colonized root fragments (40 root
fragments per gram inoculums, 85% root colonization), and external mycelium65.
Rs determination. Rs was measured from July to September in individual plot with three replicates. Each
measurement event was made in the middle of individual month (about 15th) using an Automated Soil Gas Flux
System (Li-8100A, Li-cor Inc., Lincoln, Nebraska, USA) coupled with the small PVC chamber (20 cm ? 10 cm).
The instrument was permanently installed between two rows with identical distance. In each plot, measurements
of Rs were taken inside three replicate PVC chambers with 20 cm in diameter and 10 cm in height, inserted to a
depth of 2?3 cm in soil, capturing respirations. The CO2 efflux from this collar mainly derived from soil organic
matter decomposition, and root and microbial respiration. Meanwhile, soil temperature and volumetric moisture
at the top of 5 cm was measured with the corresponding probes. Specifically, Rs was always measured between
8:00 and 12:00 in the morning in the sunny day without wind66.
The cumulative Rs values were calculated by the method of Bremer et al.67. Additionally, diel respiration (every
2 hours over 24-hour cycles) was periodically measured in all plots and individual collars. All of the
measurements were made in four seasons from 2014 to 2015 due to time constraints. The diel measurements were used
to calculate the annual growing season (July to September) cumulative Rs. Briefly, respiration measured during
the daytime was assumed to be the daily maximum soil CO2 efflux. Diel measurements were used to calculate the
daily minimum efflux as a percentage of maximum efflux. The daily maximum and minimum efflux were used to
calculate the average daily efflux. The cumulative flux as the product of average daily flux and the number of days
was estimated between each measurement.
Pn determination. Plants assimilated CO2 via Pn. To quantify photosynthetic performance of plant species,
the measurement was with two AMF inoculation levels using a portable open system infrared gas analyzer for
net CO2 assimilation rate of leaves in individual treatment (Li-6400, Li-cor Inc., Lincoln, Nebraska, USA). The
experiment was performed from July to September in 2014, including three candidate trees within individual
plot. Each measurement event was carried out at 08:00 to 18:00 in sunny day every 2 h, with three fully expanded
healthy sun-exposed leaves of each species. Leaves were carefully positioned in the leaf chamber when they were
exposed to the 1000 ?mol m?2 s?1 saturating quantum flux level. Parameters including the instantaneous Pn,
transpiration rate (Tr), stomatal conductance (Gs), intercellular CO2 concentration (Ci), photosynthetically active
radiation (PAR), atmosphere CO2 concentration (Ca), atmosphere temperature (Ta), leaf temperature (Tleaf), and
relative air humidity (RH) were tested.
Diurnal Pn amount was the area which surrounded by the curves of net photosynthetic rate > 0 and the time
transverse in the diurnal curves variations of species Pn. According to the principle, the diurnal net hotosynthetic
amount was calculated as follows:
where P was the diurnal total net assimilation amount (mmol.m?2.d?1), pi and pi+1 (?mol.m?2.s?1) was the
instantaneous photosynthetic rate of the beginning and next measuring point, respectively; ti and ti+1 was the time
duration of the beginning and next measuring point; n was the numbers of determination times; one hour equaled to
3600 seconds; 1 mmol equaled to 1000 ?mol.
Generally, the 20% diurnal assimilation photosynthates production was consumed by dark respiration, and
converted the assimilation into the CO2 diurnal sequestration as follows:
WCO2 = P ? (1 ? 0.2) ? 44/1000
where 44 was CO2 mole mass;WCO2 was CO2 sequestration mass in the per unit leaf area (g.m?2.d?1).
According to the Pn reaction equation CO2 + 4H2O ? CH2O + 3H2O + O2, which the formula can be calculate
the daily CO2 absorption in the per unit land area of per plant as follow:
QCO2 = Y ? WCO2
QCO2 was the daily CO2 sequestration in the per unit land area of per plant species (g.m?2.d?1).
The average CO2 uptake per day of individual plants as follow:
QCO2 = Y ? paverage ? (1 ? 0.2) ? 44/1000
Paverage = (PJul + PAug + PSep)/3
where QCO2 was the daily average CO2 sequestration of each plant (g.d?1); Paverage was the daily assimilation in the
per unit land area (mmol.m?2.d?1); Y was the total leaf area of each plant (m?2).
Soil OC, EE-GRSP and T-GRSP fractions. Soil samples were collected from 0?20 cm of the profile using
an auger (35 mm diameter) in each corresponding monitoring stage in 2014. Three cores were collected from
individual plot and combined to give one composite sample per plot of each tree species. The composite soil
samples were arid-dried and sieved through a 2 mm mesh and placed in plastic bags for chemical analysis.
A simple method for routine determination of soil OC by a modified Mebius procedure was described. It
involved a digestion of the soil sample with an acidified dichromate (K2Cr2O7-H2SO4) solution for 30 minutes
in a Pyrex digestion tube in (a) 40 tube block digester preheated to 170 ?C and (b) estimation of the un-reacted
dichromate by titration of the cooled digest with an acidified solution of ferrous ammonium sulfate using the
N-phenylanthranilic acid as an indicator.
0.25 g composite sample was extracted with 2 ml of extractant. EE-GRSP was extracted with 20 mM citrate
solution; pH 7.0 at 121 ?C for 30 min. T-GRSP was extracted with 50 mM citrate solution, pH 8.0 at 121 ?C. 90 min
was required for one soil sample and six additional sequential extractions. For the sequential extractions, the
supernatant was removed by centrifugation at 10,000 ? g for 5 min, 2 ml of 50 mm citrate, pH 8.0 was added to the
residue, and samples were autoclaved for 60 min. Extraction of a sample continued until the supernatant showed
no red-brown color typical of glomalin. Extracts from each replicate were pooled and then analyzed.
Citrate extractants were added to soil samples and disrupted by a brief (3 min) autoclave cycle. When
necessary, the extractant was adjusted with HCl solution until the pH stabilized at 7.0 for 20 mM citrate or 8.0 for
50 mM citrate solution. Samples were then subjected to 121 ?C for 90 min to extract T-GRSP or 30 min to extract
After extraction cycles completed, samples were centrifuged to remove soil particles (10,000 ? g for 5 min),
and protein in the supernatant was determined by the Bradford dye-binding assay with bovine serum albumin
as standard. Concentration of glomalin was extrapolated to mg/g of soil particles by correcting the dry weight of
coarse fragments >0.25 mm included in the weight of aggregates and the volume of extractant.
Data analysis. To assess the four plant species with and without AMF inoculation treatments to long-term
exposure and potentially elucidate the role of AMF in previous response, the relationship of Rs and Pn, Rs and soil
temperature, and carbon storage and AMF inoculation of the key issues have been a focus of this study.
The experiment was at two AMF inoculation levels with four plant species. To determine main effects of AMF
inoculation on soil temperature and Rs variables, mixed model restricted maximum likelihood estimation with
repeated measures was used (PROC MIXED; version 8.0; SAS Institute Inc., Cary, NC, USA, 2003). Turkey?s HSD
multiple comparison was used to identify the differences between two AMF inoculation levels.
An exponential model was used to calculate soil temperature sensitivity on Rs68,69.
Rs = aebT
where Rs is soil CO2 efflux (?mol m?2 s?1), T is soil temperature (?C) at 0?5 cm depth, a is the basal Rs, b is
temperature sensitivity of CO2 efflux. The respiratory quotient (Q10) was calculated as Q10 = e10b.
Regression coefficients, correlations, figures and curves were obtained by the Sigma-Plot software package
(version 11.0, San Jose, California, USA). Analysis was performed to reveal the differences of two AMF
inoculation levels with the relevant parameters; differences in means were revealed by LSD (P < 0.05) with SAS
software package. To determine the effect of AMF on photosynthetic parameters, the data set was divided into two
parts; the results were insensitive to variation in species groupings as the sample size was not unduly restricted.
Differences in slopes were determined by a dummy variable representing the interaction between independent
variable (AMF inoculation level) and plant species in the regression analyses.
Cumulative carbon calculations. To assess the effect of soil volumetric moisture on carbon
accumulation, the cumulative carbon (Cumulative-C) was fitted using a combined exponential and quadratic function as
?Cumulative?C = (aebT) [2.12(?v ? min ?v) (max ?v ? ?v)c ]
where ?v is the volumetric moisture content (the minimum soil volumetric water content of our data set was 3.1%
and the maximum was 37.6%, respectively) and c is the coefficient for soil moisture.
The study was supported by the National Science Foundation of China (51574253) and the Fund for 863 Programs
(2013AA102904) of the Ministry of the Science and Technology, PR China and the Bilateral Corporation on the
Prospectus of the Open Research Project (SKLCRSM16KFA01) between Kazakhstan and PR China.
Z.-G.W. initialized the study; Conceived and designed the experiments: Z.-G.W and Y.-L.B. performed the
experiments: Z.-G.W., B.J., Y.Z., W.-W.L., H.L., Z.-G.W. and Y.-L.B. performed the data analysis; Z.-G.W. and
Y.-L.B. drafted the manuscript; contributed reagents/materials/analysis tools: Z.-G.W., Y.-L.B., B.J., Y.Z., S.-P.P.,
W.-W.L. and H.L.
Competing financial interests: The authors declare no competing financial interests.
How to cite this article: Wang, Z.-G. et al. Arbuscular mycorrhizal fungi enhance soil carbon sequestration in
the coalfields, northwest China. Sci. Rep. 6, 34336; doi: 10.1038/srep34336 (2016).
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license, visit http://creativecommons.org/licenses/by/4.0/
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