Table of Content

20 July 2010, Volume 21 Issue 07

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Articles

Forest soil organic matter δ¹³C along a |altitudinal transect on northern slope of Changbai Mountains under effects of simulated warming.

2010, 21(07):  1621-1626. 

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The litters, bulk soils, and soil particle-size fractions were sampled from three typical natural forests, i.e., broadleaf Korean pine (Pinus koraiensis)mixed forest   (PB, altitude 740 m), spruce-fir (Picea asperata- Abies nephrolepis) forest (SF, altitude 1350 m), and  Erman’s birch (Betula ermanii) forest (EB, altitude 1996 m), on the northern slope of Changbai Mountains to analyze their organic matter δ¹³C values, and the intact soil cores (20 cm depth) from EB (high altitude) were relocated to PB and SF (low altitudes) for a year to study the responses of the δ¹³C values to simulated warming. It was shown that the litters had a significantly lower δ¹³C value than the soils, and the δ¹³C values of the litters and soils increased downward through the litter- and soil layers in all the three typical forest types. Soil particlesize fractions had an increased δ¹³C value with decreasing particle size fractions. The δ¹³C value of the litters was in the order of SF (-28.3‰)>PB (-29.0‰) >EB (-29.6‰), while that of the soils was in the order of EB (-25.5‰) >PB (-25.8‰) >SF (-26.2‰). Over one-year soil warming (an increment of 0.7 ℃-2.9 ℃), the δ¹³C values of  the bulk soils and soil particle-size fractions all presented a decreasing  trend, and the decrement of the δ¹³C value was larger in <2 μm (0.48‰) and 2-63 μm fractions (0.47‰) than in >63 μm fraction (0.33‰).  The results suggested that climate warming could have great effects on the older organic carbon associated with fine soil particle-size fractions.

Spatial heterogeneity of soil inorganic nitrogen in a broadleaved-Korean pine mixed forest in Changbai Mountains of Northeast China

2010, 21(07):  1627-1634. 

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Geostatistic methods were applied to study the spatial heterogeneity of top soil (0-10 cm) ammonium N and nitrate N in a broadleaved-Korean pine mixed forest of Changbai Mountains, Northeast China. The semi-variogram of soil ammonium N and nitrate N could be well fitted by spherical or Gaussian model. The spatial distribution of soil ammonium N and nitrate N all exhibited moderate autocorrelation, with the structural ratio being 0.70%-41.47% and 32.26%-52.66%, and theautocorrelation degree of soil ammonium N was smaller than that of soil nitrateN, with the variation distance being 8.87 and 9.76 m, respectively. Spatially, soil ammonium N and nitrate N were distributed in patches, and the spatial heterogeneity of soil ammonium N was higher than that of soil nitrate N. There was a significant negative correlation between soil nitrate N and soil moisture content, while soil ammonium N had less correlation with soil moisture.

Soil soluble organic nitrogen content in different forest stands in Wanmulin Nature Reserve.

2010, 21(07):  1635-1640. 

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An investigation was made on the soil soluble organic nitrogen (SON) in two natural forests Altingia gracilies (ALG) and Castanopsis carlesii  (CAC) and an adjacent 35-year-old Cunninghamia lanceolata (CUL) plantation in Wanmulin Nature Reserve in Jianou, Fujian Province. Among the three forest stands, ALG had a significantly higher content of soil SON, being 95.3, 78.3, and 72.5 mg·kg^-1in 0-5 cm, 5-10 cm, and 10-20 cm soil layers,respectively (P＜0.05), while CAC and CUL had lesser differences in their soil SON content, which was 74.5, 70.1, and 65.6 mg·kg^-1 in the three soil layers for CAC, and 78.6, 68.9, and 69.1 mg·kg^-1 in the three soil layers for CUL, respectively. The proportion of SON to total soluble nitrogen (TSN) in 0-20 cm soil layer was 79.17-80.78% for CAC, 68.64%-74.51% for CUL, and 59.97%-69.66% for ALG. With increasing soil depth, the proportion of soil SON to soil TSN and total nitrogen (TN) for the three forest stands all increased. Soil SON content had a significant positive correlation with soil organic carbon (r=0.982,P＜0.01), and also, had definite correlations with soil TSN, TN, NH₄⁺-N, and NO₃^--N. It also correlated with the factors such as forest type, topography, altitude, and tree age.

Soil respiration in subtropical forests and model simulation of its relationships with soil temperature and moisture content.

2010, 21(07):  1641-1648. 

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By using Li-6400-09 system, an in situ measurement on the soil respiration, soil temperature, and soil moisture content in three main forest types (evergreen broadleaved forest, Cunninghamia lanceolata plantation, and Phyllostachys pubescens forest) in subtropical area of China was conducted, with the relationships between soil respiration and soil temperature and moisture content simulated by several models. The C flux of soil respiration in P. pubescens forest, evergreen broadleaved forest, and C. lanceolata plantation was 12.84, 11.70, and 7.12 t C·hm^-2·a^-1,respectively, and the soil respiration in these three forest types had similar diurnal and seasonal variations, with the maximum value at 11:00-12:00 and the minimum value at 1:00-3:00, and the highest value in August and September while the lowest value in December and January.Van′t  Hoff equation and Lloyd & Taylor function had less difference in describing the relationships between soil respiration and soil temperature, while the soil respiration rate predicted by Lloyd & Taylor function was smaller than the observed value. Quadratic model and power function model could well simulate the relationship between soil respiration and soil moisture content. Soil moisture content positively or negatively affected soil respiration, but the effects only reached significant level in C. lanceolata plantation. Comparing with single-factor equation, two-factor equation (soil temperature and moisture content) could better describe the responses of soil respiration to changed soil temperature and moisture content. Multivariate analysis of covariance showed that after eliminating the effects of soil temperature and moisture content, forest type had significant effects on soil respiration (R²=0.541). Other factors, such as air temperature, air relative humidity, and photosynthetic radiation also affected soil respiration, and the effects of air temperature reached significant level.

Effects of simulated nitrogen deposition on soil respiration in a Neosinocalamus affinis plantation in Rainy Area of West China

2010, 21(07):  1649-1655. 

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From December 2007 to November 2008, an in situ experiment was conducted to study the effects of simulated nitrogen deposition on the soil respiration in a Neosinocalamus affinis plantation in Rainy Area of West China. Four treatments were installed, i.e., 0 (CK), 50, 150, and 300 kg N·hm^-2·a^-1, and soil respiration rate was measured by infrared gas analyzer. In the test plantation, soil respiration rate had a distinct seasonal fluctuation, with the highest (3.36±0.20 μmol·m^-2·s^-1) by the end of July and the lowest by the end of February (0.33±0.07 μmol·m^-2·s^-1). There was a significant exponential relationship (P<0.001) between soil respiration rate and soil temperature, and the temperature at 10 cm soil depth explained 91.6% of the seasonal change of soil respiration. However, less relationship was observed between soil respiration rate and soil moisture content (R²=0.0758). From June to November 2008, the contribution of root respiration to total soil respiration ranged from 46% to 59%. The annual release amount of CO₂ in treatments 50, 150, and 300 kg·hm^-2·a^-1 was 23.6%, 46.7%, and 50.5% lower than that in CK (2.17×10⁴ kg ·hm^-2), and the Q₁₀ value of soil respiration rate in treatments 0, 50, 150, and 300 kg·hm^-2·a^-1 was 3.72, 3.51, 2.95, and 2.71, respectively.

Simulation of carbon cycle in Qianyanzhou artificial masson pine forest ecosystem and sensitivity analysis of model parameters.

2010, 21(07):  1656-1666. 

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By using modified carbon-water cycle model EPPML (ecosystem productivity process model for landscape), the carbon absorption and respiration in Qianyanzhou artificial masson pine forest ecosystem in 2003 and 2004 were simulated, and the sensitivity of the model parameters was analyzed. The results showed that EPPML could effectively simulate the carbon cycle process of this ecosystem. The simulated annual values and the seasonal variations of gross primary productivity (GPP), net ecosystem productivity (NEP), and ecosystem respiration (R_e) not only fitted well with the measured data, but also reflected the major impacts of extreme weather on carbon flows. The artificial masson pine forest ecosystem in Qianyanzhou was a strong carbon sink in both 2003 and 2004. Due to the coupling of high temperature and severe drought in the growth season in 2003, the carbon absorption in 2003 was lower than that in 2004. The annual NEP in 2003 and 2004 was 481.8 and 516.6 g C·m^-2·a^-1, respectively. The key climatic factors giving important impacts on the seasonal variations of carbon cycle were solar radiation during early growth season, drought during peak growth season, and precipitation during post-peak growth season. Autotrophic respiration (R_a) and net primary productivity (NPP) had the similar seasonal variations. Soil heterotrophic respiration (R_h) was mainly affected by soil temperature at yearly scale, and by soil water content at monthly scale. During wet growth season, the higher the soil water content, the lower the R_h was; during dry growth season, the higher the precipitation during the earlier two months, the higher the R_h was. The maximum RuBP carboxylation rate at 25 ℃ (V_m25), specific leaf area (SLA), maximum leaf nitrogen content (LN_m), average leaf nitrogen content (LN), and conversion coefficient of biomass to carbon (C/B) had the greatest influence on annual NEP. Different carbon cycle process could have different responses to sensitive parameters. For example, the increase of V_m25and LN could effectively promote carbon absorption and respiration, the decrease of LN/LN_m could decrease the carbon absorption and respiration, and, the increase of SLA and C/B could promote carbon absorption but inhibit soil respiration. However, the most sensitive parameters derived from annual carbon fluxes were not completely the same as those derived from growth season or non-growth season carbon fluxes.

Spatial heterogeneity of soil nutrients in Karst area’s Mulun National Nature Reserve.

2010, 21(07):  1667-1673. 

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Soil samples were collected from the depression (200 m×100 m) in Karst area’s Mulun National Nature Reserve by grid sampling method (20 m×20 m), with the spatial heterogeneity of soil nutrients analyzed by the methods of classic statistics and geo-statistics. The soil pH showed small variation, while the soil nutrients showed moderate variation, being in the order of available phosphorus (AP) > available potassium (AK) > available nitrogen (AN) > organic matter (OM) > total potassium (TK) > total phosphorus (TP) > total nitrogen (TN). Spherical model fitted best for soil pH, exponential model fitted best for soil TK and AK, and Gaussian model fitted best for other variables. The variation range of soil pH and AK was smaller, being 58.1 m and 41.1 m, respectively, that of soil OM, TN, TP, AN, and AP was from 100 m to 150 m, and that of soil TK was the largest (463.5 m). Soil TK and TN showed moderate spatial autocorrelation, while other soil nutrients showed strong spatial autocorrelation. Soil pH and AK presented fragmented patch distribution, showing high heterogeneity, while soil OM, TP, and TK changed gently, high in the middle and low in two sides. The spatial patterns of soil AN and AP were similar, i.e., increased with landform slope.Soil TN had a distribution pattern of low in the middle and high in two sides. Vegetation, topography, and high heterogeneity of micro-habitat were the main factors caused the differences of the spatial distribution patterns of soil nutrients in the Reserve.

Dynamics of biomass- and nutrient accumulation in a Chinese-fir plantation.

2010, 21(07):  1674-1680. 

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Based on the over 30 years observation data in Huitong National Research Station of Forest Ecosystem under Chinese Academy of Sciences and related literatures, this paper analyzed the dynamics of the biomass-and nutrient accumulation and allocation in a Chinese-fir (Cunninghamia lanceolata) plantation, and the effects of rotation length and harvest intensity on the nutrient input/output. The results showed that stand age was the main factor affecting the biomass- and nutrient accumulation and allocation, and different organs had significant differences in their biomass- and nutrient storage. Stand age and different organs explained 37.1% and 40.3 % of the variations of biomass-and nutrient storage, respectively. With the increase of stand age, the proportions of biomass and nutrients allocated to stem increased, while those allocated to foliage decreased. The accumulation rates of biomass and nutrients peaked at the age of 17 and 13, respectively, indicating that the nutrients reached their maximum accumulation rate ahead of the biomass. The nutrient requirement per unit dry biomass production decreased rapidly from the stand age 3 to 20 and reached a steady state after then, suggesting that the nutrient use efficiency increased with stand age. The analysis of different harvest scenarios showed that to prolong rotation length and to lower utilization intensity could reduce nutrient output. For example, if the rotation length was prolonged from 28 years to 56 years and only stem was harvested, the harvested biomass would be decreased by 31.57%, and the output of N, P, K, Ca, and Mg would be decreased by 42.02%, 58.93%, 27.70%, 31.07%, and 45.26%, respectively.

Simulation of timber-harvesting area in Xiao Xing’anling Mountains under climate change.

2010, 21(07):  1681-1688. 

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By using the spatially explicit forest landscape model (LANDIS 6.0 PRO), the percentages of timber-harvesting area in Xiao Xing’anling Mountains under current harvesting scenario and under 11 harvesting scenarios with alternating harvesting intensities (alternating time was 10, 20 and 30 years, respectively) in 2000-2400 under climate change were simulated. Alternating harvesting intensity could increase the harvesting area. Comparing with current harvesting scenario, the simulated scenarios could increase the harvesting area by 3%-5% at shortterm (10-30 years), 2.5%-7% at medium term (40-60 years), and 3.5%-8% at long term (70-100 years). On the whole, the current total harvesting area was still high. Alternating harvesting-intensity could increase the harvesting area within a definite term, but the effect  would be  unsustainable. To have a sustainable development of forestry in the study area, it is necessary to reduce the harvesting intensity and change the forest management policy.

Effects of groundwater level on chlorophyll fluorescence characteristics of Tamarix hispida in lower reaches of Tarim River.

2010, 21(07):  1689-1696. 

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Based on the monitoring data of groundwater level at the typical sections in lower reaches of Tarim River, three survey plots nearby the ecological monitoring wells with groundwater depths > 6 m were selected to investigate the chlorophyll fluorescence characteristics of Tamarix hispida and its photosynthetic activity of PSII under effects of different groundwater depths. With increasing groundwater depth, the chlorophyll fluorescence parameters such as actual photochemical efficiency of PSⅡ in the light (Φ_PSII), electron transport rate (ETR), and photochemistry quenching (q_P) of T. hispida decreased, while the non-photochemistry quenching (q_N, NPQ) and the yield for dissipation by down-regulation (Y_NPQ) increased remarkably, and the maximal photochemical efficiency of PSII (F_v/F_m) maintained an optimum value. All the results suggested that the PSII photosynthetic activity of T. hispida under drought stress declined with increasing groundwater depth, and the greater excess energy could result in more risk of photo-inhibition. However, the good adaptability and drought tolerance of T. hispida could make its PSII not seriously damaged, though the drought stress actually existed.

Responses of Cotinus coggygria var. cinerea  photosynthesis to soil drought stress.

2010, 21(07):  1697-1701. 

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By using a portable photosynthetic system (CIRAS-2), this paper studied the photosynthetic characters of 3-year-old Cotinus coggygria var. cinerea under effects of different soil water regime (enough supply, light stress, medium stress, and heavy stress) and light intensity. Soil water regime had significant effects on the photosynthetic parameters of C. coggygria. With increasing drought stress, the net photosynthetic rate, transpiration rate, and apparent yield all declined apparently, while the light compensation point increased. The highest water use efficiency was found under light water stress (soil relative water content being about 60%-65%). C. coggygria had higher net photosynthetic rate and higher water use efficiency under a wide range of high light intensity (photosynthetically active radiation being 1000-1800 μmol·m^-2·s^-1), but had lower efficiency of light absorbance and conversion, i.e., lower apparent quantum yield, under low light intensity, which was declined more significantly when the soil water stress was intensified.

Allelopathic effects of Artemisia frigida on three Poaceae plants seed germination and seedling growth.

2010, 21(07):  1702-1708. 

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Aqueous extracts of Artemisia frigida leaf and stem and soils beneath A. frigida  were used to test their allelopathic effects on the seed germination and seedling growth of three Poaceae plants (Leymus chinensis, Stipa krylovii, and Cleistogenes squarrosa) on Leymus chinensis grassland. The aqueousextracts of A. frigida leaf and stem decreased the seed germination index of testplants and prolonged their seed germination time, and inhibited the shoot growth of the three plants and the root growth of S. krylovii. The aqueous extracts at concentration ≥0.075 g·ml^-1 presented a strong inhibition on the root growth of L. chinensis, while those at concentration ≤0.05 g·ml^-1 had less effects. For the root growth of C. squarrosa, the aqueous extracts showed a “low-promotion and high-inhibition effect”. Under the effectsof A. frigida soil, the seedling growth of test plants was inhibited. The sensitivity of test plants to the allelopathic effects of A. frigida was in the order of S. krylovii＞L. chinense＞C. squarrosa, with a higher sensitivity of root growth than shoot growth.

Effects of wildernesstraining -Ailuropoda melanoleuca’s feeding and artificial harvesting on population structure of Fargesia robustaclone.

2010, 21(07):  1709-1717. 

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From 2003 to 2007, the methods of plot sampling and positioning observation were adopted to investigate the population density, basal diameter, and plant height of Umbrella bamboo (Fargesia robusta) clone in the Wolong Natural Reserve of China. In the meantime, the effects of wildernesstraining Ailuropoda melanoleuca’s feeding and artificial harvesting on the population regeneration of the clone were studied, and the responses of the population structure (age-, size-, and height-class distribution) to different management modes (A. melanoleuca’s feeding, artificial harvesting, control) were approached with the scale- and shape-parameters of Weibull distribution function. The results showed that under the same F. robusta clone population density and the same environmental conditions (P>0.05), A. melanoleuca’s feeding and artificial harvesting promoted the clone regeneration. After 3 years natural restoration, the population density of the clone tended to be equal to the control, and came to a steady state (P>0.05). The curves of size- and height-class distribution as well as the scale-and shape-parameters had no significant differences between A. melanoleuca’s feeding plot and control plot. The curves of size- and height-class distribution in artificial harvesting plot were in converse “J” shape, and the values of the scale- and shape-parameters were significantly lower than those in the other two plots (P<0.05). The young and adult bamboos in artificial harvesting plot were far poor in shoot quality, and A. melanoleuca rejected to feed with them.

Effects of shading on the nitrogen redistribution in wheat plant and the wheat grain quality.

2010, 21(07):  1718-1724. 

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aking winter wheat (Triticum aestivum L.) cultivars Yangmai 158 (shading- tolerant) and Yangmai 11 (shading-sensitive) as test materials, this paper
 studied the effects of shading at the stages from jointing to maturity on the plant N redistribution, grain yield, and grainand dough quality of the cultivars. The treatments were nonshading, 22% shading, and 33% shading. Under shading, the grain yield and its protein content of Yangmai 158 and Yangmai 11 decreased by 4.1%-9.9% and 3.0%-8.3%, and 15.3%-25.8% and 10.4%-14.1%, respectively, compared with nonshading. With the increase of shading intensity, the grain N content was increasingly dependent on the N accumulated after anthesis. Shading decreased the redistribution of N stored pre-anthesis in the vegetative organs to the grain, but increased the redistribution efficiency of N accumulated pre-anthesis (RENP) in leaves while decreased the RENP in sheathes and stems, and in hulls and rachises. Therefore, the mean RENP in the vegetative organs was not essentially altered by shading. The grain protein content increased significantly under shading, which could be related to the “condense effect”, i.e., the decrement of grain protein content was much less than that of grain yield. In addition, shading had less effects on the contents of grain albumin and globulin but increased the contents of grain gliadin and glutinin significantly, and accordingly, the grain wet gluten content, dough development time, and dough stability time increased, while the dough softening degree decreased.

Relationships between rice empty grain rate and low temperature at booting stage in Heilongjiang Province.

2010, 21(07):  1725-1730. 

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Six major rice varieties (Longdao 3, Kendao 12, Kongyu 131, Longdao 7, Longjing 16, and Songjing 6) in Heilongjiang Province were treated with low temperature 15 ℃, 17 ℃, and 19 ℃for 2, 4, 6 and 8 days at booting stage, and the relationships between their empty grain rate per panicle and low temperature at booting stage were analyzed by using linear interpolation and linear regression methods. In the province, the critical temperature of sterile-type cool injury was 17 ℃ for sensitive varieties, and 16 ℃ for resistant varieties. The most sensitive period of rice to low temperature was 14-18 days before heading. At 15 ℃ for 8 days, the empty grain rate of Songjing 6 and Kendao 12 increased significantly, while that of Kongyu 131 increased less, suggesting that the cold tolerance of Songjing 6 and Kendao 12 was relatively weak, while Kongyu 131 was insensitive to low temperature. There was a significant correlation between the accumulated cool temperature and the empty grain rate of Kendao 12, Longjing 16, and Kongyu 131 (P<0.01). With the increase of accumulated cool temperature, the rice empty grain rate increased significantly, but the increment varied with rice variety.

Effects of water deficit at seedling stage on maize root development and anatomical structure.

2010, 21(07):  1731-1736. 

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A pot experiment was conducted to study the effects of water deficit at seedling stage on the root development and anatomical structure of maize. Four
treatments were installed, i.e., 75%-85% of  field capacity (control), 65%-75% of  field capacity (light deficit), 55%-65% of  field capacity (moderate deficit), and 45%-55% of  field capacity (heavy deficit). Drought stress inhibited the plant growth. With increasing drought stress, the root length, diameter, and total biomass reduced, while the root vigor, root/shoot ratio, and root apex polysaccharide content increased. Under moderate water deficit, the branch root hair length, root hair density, and total length of root hair reached to the maximum. Anatomical observation showed that the decrease of root diameter was mainly due to the decrease of root central cylinder area and of root vessel diameter. No significant difference was observed in the root vessel number among the treatments, but the root vessel wall became irregular under water deficit. The increase of root apex polysaccharide content mainly occurred in the epidermal cells and pileorhiza cells. In epidermis cells, the polysaccharide was mainly in dissociation, while in pileorhiza cells, polysaccharide was mainly as starch grains. In sum, under water deficit, maize root could alter its vessel structure, increase the polysaccharide content in epidermal cells and pileorhiza cells, and expand the total surface area of root hair to enhance the water-absorbing ability of hair root, and to strengthen the drought resistance of maize. However, with the increase of water deficit, root hair didn’t have unrestrictive growth, while in adverse, its growth was inhibited or damaged under severe drought.

Effects of planting density on the grain yield and source-sink characteristics of summer maize.

2010, 21(07):  1737-1743. 

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Taking high-yielding summer maize cultivars Zhengdan 958 (ZD 958) and Denghai 661 (DH 661) as test materials, this paper studied the effects of different planting density (22500, 45000, 67500, 90000, and 112500 plant·hm^-2) on the grain yield and source-sink characteristics of the cultivars in four regions, i.e., Shandong Agricultural University, Wenkou, Yanzhou, and Laizhou. At the planting density 112500 plant·hm^-2, the grain yield and the biomass of the cultivars were the highest, being 19132 and 36965 kg·hm^-2, respectively. Comparing with those at the planting densities 22500 and 67500 plant·hm^-2, the grain yield at the planting density 112500 plant·hm^-2 was increased by 72% and 48%, and the biomass was increased by 152% and 112%, respectively. With the increase of planting density, the leaf area index (LAI) increased significantly, while the leaf area per plant (LA), the maximum number of filaments, the grains per ear, and the 1000grain weight all decreased. The harvest index and the grain-leaf ratio decreased with increasing planting density, but no significant change was observed when the planting density was higher than 67500 plant·hm^-2, suggesting that at higher planting densities, summer maize could improve their grain yield via increasing population sink.

Responses of soil structure to seasonal freezing-thawing in a typical black soil cultivated region.

2010, 21(07):  1744-1750. 

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Taking the soil in a typical black soil cultivated region as test object, this paper analyzed its aggregate size distribution, wedge resistance, bulk density, porosity, saturation degree, and generalized structure index after a seasonal freezing-thawing cycle, and evaluated the effects of the freezing-thawing cycle on the soil structural characters. The seasonal freezing-thawing cycle aggravated the disruption of air-dried aggregates, but strengthened the aggregation of water-stable aggregates and lowered their destruction rate. After the freezing-thawing cycle, soil wedge resistance decreased by 15.45%, and soil bulk density remained relatively constant from 1.10 to 1.11 g·cm^-3. The volume percent of soil solid phase increased, and soil total porosity and capillary porosity decreased to different degree. Soil saturation degree was improved by 13.06%, which in turn decreased the soil potential storage capacity. Seasonal freezing-thawing cycle improved the soil structure and soil arability and increased the erosion resistance of soil aggregates, but decreased the soil erosion resistance and increased the risk of the water erosion of black soil.

Diversity of bacterial community in rhizosphere soils under effects of continuously planting burley tobacco.

2010, 21(07):  1751-1758. 

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By using T-RFLP approach, this paper studied the dynamic changes of bacterial community in the rhizosphere soils under continuously planting burley tobacco for 1, 2 and 4 years. With the increasing  of continuous planting years, the Shannon index and Margalef index of bacterial community in the rhizosphere soils decreased after an initial increase. After 4-year continuous planting, the diversity of the bacterial community decreased significantly, and the community structure became simple. The similarity coefficient of the bacterial community in the rhizosphere soils of continuously planting burley tobacco for 1 and 2 years and of the control was decreased with increasing year of continuous planting. Actinobacteria were predominant in the soils under 1 and 2 years continuous planting and in the control, but decreased in the soil continuously planted with burley tobacco for 4 years, in which, Bacilli of Firmicute was the dominant. It was suggested that continuously planting burley tobacco could result in the decrease of beneficial microbes such as Sphingomonas and Streptomyces while increase the species of pathogenic bacteria such as  Bacillus cereus  in rhizosphere soil, which in return, could lead to the imbalance of bacterial community and deteriorate the micro-ecological conditions in rhizosphere soil.

Effects of selective microbial inhibitors on the microbial transformation of phosphorous in aggregates of highly weathered red soil with rice straw amendment.

2010, 21(07):  1759-1765. 

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In order to further understand the mechanisms of microbial immobilization of phosphorous (P) in highly weathered red soil with organic amendment, an incubation test was conducted to investigate the roles of microbial functional groups in the transformation of P in 0.2-2 mm soil aggregates. Throughout the 90-day incubation period, amendment with rice straw induced a substantial increase in the amounts of microbial biomass C and P, Olsen-P, and organic P in the aggregates. Comparing with rice straw amendment alone, the amendment with rice straw plus fungal inhibitor actidione decreased the amount of microbial biomass C in the aggregates by 10.5%-31.8% in the first 30 days. Such a decrement was significantly larger than that (6.8%-11.6%) in the treatment amended with rice straw plus bacterial inhibitors tetracycline and streptomycin sulphate (P<0.01). After the first 30 days, the microbial biomass Cremained constant. In the first 20 days, the amount of microbial biomass P in the aggregates was 10.0%-28.8% higher in the treatment amended with bacterial inhibitors than in the treatment amended with fungal inhibitor (P<0.01). All the results suggested that that both the fungal and the bacterial groups were involved in the microbial immobilization of P in the soil aggregates, and the fungal group played a relativelylarger role.

Effects of long-term fertilization on soil enzyme activities and soil physicochemical properties of facility vegetable field.

2010, 21(07):  1766-1771. 

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An investigation was made on a long-term fertilization facility vegetable field at Shenyang Agricultural University to study the effects of long-term fertilization on the soil enzyme activities and soil physicochemical properties. Long term application of organic manure combined with or without nitrogen fertilizer increased the contents of soil organic matter, N, P, and K, and improved the soil physical properties and soil invertase, urease, and neutral phosphatase activities. However, longterm application of nitrogen fertilizer alone decreased  soil pH and soil enzymes activities. Significant positive correlations were observed between soil invertase activity and soil organic matter and total P, between soil urease activity and soil organic matter, alkali-hydrolyzable N, total and available P, and available K, and between soil neutral phosphatase activity and soil organic matter, total P, and available K, but less correlation was found between soil dehydrogenase activity and soil nutrients.

Variations of soil fertility level in red soil region under long-term fertilization.

2010, 21(07):  1772-1778. 

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Based on the long-term (1982-2007) field experiment of “anthropogenic mellowing of raw soil” at the Qiyang red soil experimental station under Chinese Academy of Agricultural Sciences, and by using numerical theory, this paper studied the variations of the fertility level of granite red soil, quaternary red soil, and purple sandy shale soil under six fertilization patterns. The fertilization patterns included non-fertilization (CK), straw-returning without fertilizers (CKR), chemical fertilization (NPK), NPK plus straw-return (NPKR), rice straw application (M), and M plus straw-return (MR). The soil integrated fertility index (IFI) was significantly positively correlated with relative crop yield, and could better indicate soil fertility level. The IFI values of the three soils all were in the order of NPK, NPKR > M, MR > CK, CKR, with the highest value in treatment NPKR (0.77, 0.71, and 0.71 for granite red soil, quaternary red soil, and purple sandy shale soil, respectively). Comparing with that in the treatments of no straw-return, the IFI value in the treatments of straw return was increased by 6.72%-18.83%. A turning point of the IFI for all the three soils was observed at about 7 years of anthropogenic mellowing, and the annual increasing rate of the IFI was in the sequence of purple sandy shale soil (0.016 a^-1) > quaternary red clay soil (0.011 a^-1) > granite red soil (0.006 a^-1). It was suggested that a combined application of organic and chemical fertilizers and/or straw return could be an effective and fast measure to enhance the soil fertility level in red soil region.

Allelopathy of grape root aqueous extracts.

2010, 21(07):  1779-1784. 

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Taking the tissue-cultured seedlings of grape cultivar Red Globe as test objects, this paper examined the effects of their root aqueous extracts on seedling’s growth, with the allelochemicals identified by LC-MS. The results showed that 0.02 g·ml^-1(air-dried root mass in aqueous extracts volume; the same below), 0.1 g·ml^-1, and 0.2 g·ml^-1 of the aqueous extracts inhibited the growth of the seedlings significantly, and the inhibition effect increased with increasing concentration of the extracts. The identified allelochemicals of the extracts included ρ-hydroxybenzoic acid, salicylic acid, phenylpropionic acid, and coumaric acid. Pot experiment showed that different concentration (0.1, 1， and 10 mmol·L^-1) salicylic acid and phenylpropionic acid inhibited the seedling’s growth remarkably. With the increasing concentration of the two acids, the plant height, stem diameter, shoot- and root fresh mass, leaf net photosynthetic rate and starch content, and root activity of the seedlings decreased, while the leaf soluble sugar and MDA contents increased. No obvious change pattern was observed in leaf protein content.

Runoff and sediment processes and anti-erosion effects of grass-covered earth road in loess hilly region.

2010, 21(07):  1785-1791. 

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A laboratory simulation test with slope-adjustable steel tank and artificial rainfall was conducted to study the runoff and sediment processes of uncovered and Poa pratensis L.- planted earth roads, and the anti-erosion effects of P. pratensis-  planted earth road. At the same rainfall intensity and slope, the runoff coefficient of  P. pratensis- planted earth road was larger than that of uncovered earth road. For the two kinds of earth roads, their runoff coefficients all increased with increasing rainfall intensity and slope. At the same slope but different rainfall intensity, the runoff coefficient had a logarithmic relationship with rainfall duration, and a quadratic relationship with slope or rainfall intensity. Soil erosion rate increased with increasing rainfall intensity or slope, and was smaller on the P. pratensis-  planted earth road at the same rainfall intensity. The average anti-erosion efficacy of P. pratensis-  planted earth road was 47.22% at different rainfall intensity, and was 26.24% at different slope. Because of its higher roughness and higher road surface resistance coefficient, P. pratensis  planted earth road had a lower sediment yield and a decreased sediment transport.

Evaluation of forest ecosystem services value in Liaoning Province.

2010, 21(07):  1792-1798. 

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Based on the long-term located observation of forest ecosystem, and by using the 2006 forest resources inventory data of Liaoning Province and the forest industry standard of the People’s Republic of China（LY/T 1721-2008, specification for assessment of forest ecosystem services in China), an evaluation was made on the material quantity and services value of main forest ecosystems in fourteen cities of Liaoning Province. In this province, the forest ecosystem services value supplied by water storage, soil conservation, C fixation, O₂ release, nutrients accumulation, environment purification, biodiversity conservation, and forest recreation in 2006 was 2591.72×10⁸ yuan, which was 8.54 times of the forestry production value and 28.02% in the GDP of the province. The services value of water storage, biodiversity conservation, C fixation, and O₂ release occupied 79.09% of the total, being the main forest ecosystem services in the province. Economic forest and shrub had smaller per unit services value but larger area, and hence, their ecosystem services value should not be ignored. Abies fargesii forest, Phellodendron amurense forest, Juglans mandshurica forest, and Fraxinus mandshurica forest were the representative zonal vegetations in Liaoning Province, which had high value in biodiversity conservation. Under the effects of climate and other factors, the forest area and forest quality in west Liaoning were lower than those in east -Liaoning.

Multi-scale spatial heterogeneity of urban wetland water quality in east suburb of Nanjing City.

2010, 21(07):  1799-1804. 

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An investigation was made on the water quality and plant community in 17 urban wetlands in east suburb of Nanjing City, and the spatial heterogeneity of the water quality was analyzed at ecosystem scale, catchment scale, and functional landscape scale. Wetland type and the characteristics of plant community were the main factors affecting the water quality at ecosystem scale. Primitive wetland had the best water quality, followed by reconstructed wetland, and secondary wetland. The higher plant coverage the wetland had, the better the water quality was. Land use type was the main factor affecting the water quality at catchment scale. Constructive land had greater effects on water nutrients content, while woodland mainly affected water dissolved oxygen. Human activity was the main factor affecting the water quality at functional landscape scale, and the effects differed with different water quality indices.

Ecological sensitivity of Shanghai City based on GIS spatial analysis.

2010, 21(07):  1805-1812. 

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In this paper, five sensitivity factors affecting the eco-environment of Shanghai City, i.e., rivers and lakes, historical relics and forest parks, geological disasters, soil pollution, and land use, were selected, and their weights were determined by analytic hierarchy process. Combining with GIS spatial analysis technique, the sensitivities of these factors were classified into four grades, i.e., highly sensitive, moderately sensitive, low sensitive, and insensitive, and the spatial distribution of the ecological sensitivity of Shanghai City was figured out. There existed a significant spatial differentiation in the ecological sensitivity of the City, and the insensitive, low sensitive, moderately sensitive, and highly sensitive areas occupied 37.07%, 5.94%, 38.16%, and 18.83%, respectively. Some suggestions on the City’s zoning protection and construction were proposed. This study could provide scientific references for the City’s environmental protection and economic development.

Tourism function zoning of Jinyintan Grassland Scenic Area in Qinghai Province based on ecological sensitivity analysis.

2010, 21(07):  1813-1819. 

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Based on the statistical data of natural ecology and social economy in Jinyintan Grassland Scenic Area in Qinghai Province in 2008, an evaluation index system for the ecological sensitivity of this area was established from the aspects of protected area rank, vegetation type, slope, and land use type. The ecological sensitivity of the sub-areas with higher tourism value and ecological function in the area was evaluated, and the tourism function zoning of these sub-areas was made by the technology of GIS and according to the analysis of eco-environmental characteristics and ecological sensitivity of each sensitive sub-area. It was suggested that the Jinyintan Grassland Scenic Area could be divided into three ecological sensitivity sub-areas (high, moderate, and low), three tourism functional sub-areas (restricted development ecotourism, moderate development ecotourism, and mass tourism), and six tourism functional sub-areas (wetland protection, primitive ecological sightseeing, agriculture and pasture tourism, grassland tourism, town tourism, and rural tourism).

Effects of soil components on zinc sorption-desorption by microaggregates in a paddy soil in Mingshan River watershed.

2010, 21(07):  1820-1828. 

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By using simulation-incubation test and selective dissolution method, this paper studied the effects of soil components on the zinc sorption-desorption by the microaggregates from a typical paddy soil in Mingshan River watershed. The Zn²⁺ sorption capacity of bulk soil and microaggregates was significantly correlated with the contents of soil organic matter, free oxide iron, amorphous oxide iron, and cation exchange capacity. Whether or not the soil components were removed, the Zn²⁺ sorption by the bulk soil and microaggregates fitted well to the Freundlich isotherm model, and the Zn²⁺ sorption capacity was in the order of <0.002 mm microaggregates >0.25-2 mm microaggregates > bulk soil >0.002-0.053 mm microaggregates >0.053-0.25 mm microaggregates. After the removal of the soil components, the Zn²⁺ sorption capacity by bulk soil and microaggregates decreased, and the decrement was in the order of <0.002 mm microaggregates > bulk soil  >0.053-0.25 mm microaggregates, compared with that before the removal of the soil components. After the removal of organic matter, the decrement of the Zn²⁺ adsorption capacity of <0.002 mm microaggregates, 0.053-0.25 mm microaggregates, and bulk soil was 39.56%±1.97%, 26.68%±4.21%, and 36.39%±2.31%; after the removal of free oxide iron, the decrement was 30.41%±1.91%, 20.14%±3.33%, and 28.73%±1.22%; and after the removal of amorphous oxide iron, the decrement was 22.12%±1.27%, 12.43%±2.11%, and 20.15%±2.62%, respectively. The decrement of Zn²⁺sorption by bulk soil and microaggregates after the removal of the soil components was in the order of removal of organic matter > removal of free oxide iron > removal of amorphous oxide iron, and the difference among the treatments was significant. After the removal of the soil components, the non-specific adsorption of Zn²⁺ by bulk soil and microaggregates increased significantly, which increased the Zn²⁺mobility in soil, while the specific adsorption decreased, resulting in the decrease of the buffering and retention capability of the bulk soil and microaggregates to Zn²⁺.

Effects of sulfur on microbial activity and community structure in a lead-polluted paddy soil.

2010, 21(07):  1829-1834. 

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A pot experiment was conducted to study the microbial activity and community structure in a lead-polluted paddy soil under effects of amendment with
different concentration sodium thiosulfate. The amendment of the sulfur-containing substrate increased the soil oxidation-reduction potential and respiration rate, promoted the growth of soil sulfur-oxidizing bacteria, and induced some changes in soil microbial community structure. The clone sequencing indicated that the specific bands of soil microbes in sodium thiosulfate treatments had very high similarity to Bateroidetes, Thiobacillus, β-proteobacteria, and Acidobacteria. Significant changes were observed in the contents of soil carbonate- and Fe/Mn oxide- bound Pb after the amendment of sodium thiosulfate.

Heavy metals content and pollution risk assessment of cropland soils around a pesticide industrial park.

2010, 21(07):  1835-1843. 

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By the method of concentric circle distribution method, a total of 183 topsoil samples were collected from 30km² area around a pesticide industrial park in south Jiangsu Province, with the content and pollution index of soil Cd, Cr, Cu, Ni, Pb, Zn, Hg and As analyzed. The average contents of Hg, Cu, Cd,and Pb in the top soils were higher than those of the natural background values, and the contents of Hg and Cu were the highest. Taking the national standard II as the assessment criterion, the average pollution index values of Cd, Cr, Cu, Ni, Pb, Zn, and As in the top soils were all below 1, while those of the Hg and Cu were 1.59 and 1.05, respectively. In the southeast and northwest to the pesticide industrial park, soil heavy metals contamination was more serious, and, with the increasing distance to the park, the contents of soil Cd, Ni, Pb, Cr, As, Hg, Zn, and Cu increased first and then decreased to a stable level. The comprehensive pollution index of test metals indicated that the areas 200-1000 meter around the industrial park were of high risk in soil heavy metals contamination, while the areas 1000 meter beyond were safety. By using geostatistics and GIS, it was found that the pollution index of the eight heavy metals had significant spatial variability. Based on the principal component analysis and correlation analysis, it was speculated that the Zn, Ni, Cr, Pb, and As were mainly from soil parent materials, while the Hg, Cu, and Cd were mainly related to human activities.

Community structure of phytoplankton and its relationships with environmental factors in drinking water source of Jinshu Bay, Taihu Lake.

2010, 21(07):  1844-1850. 

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By using canonical correspondence analysis (CCA), this paper studied the community structure of phytoplankton and its relationships with environmental factors in the drinking water source of Jinshu Bay, Taihu Lake. A total of 7 phylum and 58 genera were identified, and the phytoplankton community was dominated by Cyanophyta, Bacillariophyta, and Chlorophyta. The quantity of phytoplankton was slightly higher in summer (250×10⁴ ind·L^-1) than in spring (238×10⁴ ind·L^-1), but the community structure differed obviously between the two seasons. In spring, Cyanophyta was the dominant phylum, and Anabaena was the dominant genus; in summer, Chlorophyta was the dominant phylum, with no domin ant genus but abundant quantity of Merismopedia and Scenedesmus. Besides temperature, the main environmental factors affecting the distribution of phytoplankton in spring were ammonium-nitrogen, total phosphorus, total nitrogen, and phosphate, while those in summer were total nitrogen, ammonium-nitrogen, phosphate, suspended solids, macrophytes, total phosphorus, and transparency.

Isolation, identification, and degrading effect of a pyrene-degrading strain SE12.

2010, 21(07):  1851-1858. 

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Using pyrene as the sole carbon and energy source, and by the method of plate sublimation, a strain SE12 was isolated from a contaminated soil near Woniushan Coking Plant in Xuzhou, China. According to the morphological, biochemical, and 16S rDNA analyses, this strain was identified as Mycobacterium sp., with 98% of homology to the rapid-growth nonpathogenic strain M. austroafricanum ATCC 33464. The optimum pH and temperature for the degradation of pyrene by SE12 were pH 9 and 30 ℃. When the soil samples were added with 100 and 200 mg·kg^-1 of pyrene and inoculated with 10⁷ CFU·g^-1of SE12, the degradation rates of pyrene reached to 97% and 99%, respectively after 28 days incubation at 30 ℃. By using primer-pairs nidAF/nidAR and nidBF/nidBR for amplification of ring-hydroxylating dioxygenase genes, it was shown that SE12 had the fragments of encoded large and small subunits of dioxygenase genes. Sequence analysis showed that these fragments were highly homologous to the known dioxygenase genes from pyrene-degrading Mycobacteria sp.

Historical range of variability in forest ecosystem management: Applications and prospects.

2010, 21(07):  1859-1866. 

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Historical range of variability (HRV) characterizes the fluctuations of ecosystem structure and processes under natural disturbances, and is helpful in understanding the causes and consequences of ecosystem change, providing the researchers and managers a reference to evaluate the present status of ecosystems and guiding managers to develop effective management strategies to ultimately drive ecosystems to a sustainable state. In recent years, HRV has played an increasingly important role in forest ecosystem management, and has been successfully used in indicating the causes of ecosystem change, conservation of biological diversity and endangered species, and restoration of ecosystem function, etc. This paper outlined the concept of HRV, and discussed the applications, limitations (lack of data, environmental change, and human impacts, etc.), and challenges of applying HRV in forest ecosystem management. Strengthening data mining, focusing on the changes of natural environment and human society, and increasing the public’s recognition of HRV would benefit the improvement of the application efficacy of HRV in forest ecosystem management, and make the forest ecosystem ultimately achieve a sustainable state.

Effects of climate change on forest soil organic carbon storage: A review.

2010, 21(07):  1867-1874. 

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Forest soil organic carbon is an important component of global carbon cycle, and the changes of its accumulation and decomposition directly affect terrestrial ecosystem carbon storage and global carbon balance. Climate change would affect the photosynthesis of forest vegetation and the decomposition and transformation of forest soil organic carbon, and further, affect the storage and dynamics of organic carbon in forest soils. Temperature, precipitation, atmospheric CO₂ concentration, and other climatic factors all have important influences on the forest soil organic carbon storage. Understanding the effects of climate change on this storage is helpful to the scientific management of forest carbon sink, and to the feasible options for climate change mitigation. This paper summarized the research progress  about the distribution of organic carbon storage in forest soils, and the effects of elevated temperature, precipitation change, and elevated atmospheric CO₂ concentration on this storage, with the further research subjects discussed.

Heavy metal-transport proteins in plants: A review.

2010, 21(07):  1875-1882. 

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The heavy metals in soil not only damage plant growth, but also threaten the health of human beings and animals through food chain. Heavy metaltransport proteins play crucial roles in the heavy metals uptake and tolerance of plants. Plant heavy metal-transport proteins can be classified as metal-uptake proteins and metal-efflux proteins. The metal-uptake proteins can transport essential heavy metals into cytoplasm, and also, transport toxic heavy metals into cytoplasm due to the absence of essential heavy metals or the competition among ions. The metal-efflux proteins are a group of detoxification proteins, which can efflux excess and toxic heavy metals from cytoplasm, or move these metals into vacuole. In recent years, the associations between elevated steady-state transcript levels of heavy metal-transporter genes and metal accumulation in plants have been revealed, and many heavy metal-transport proteins have been cloned and identified. In this paper, the metal affinity, tissue-specific gene expression, and cellular location of representative heavy metal-transport proteins were reviewed.

Arsenic speciation in edible plants: A review.

2010, 21(07):  1883-1891. 

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Arsenic (As) is a ubiquitous chemical element in environment, and the increasingly serious As pollution is highly concerned all over the world. China
has been considered as one of the countries and regions with serious As pollution in the world by the World Health Organization (WHO). Recent studies indicated that food is one of the major contributors of As in human diets. Edible plants are essential in the diet structure in human life, which often contain high level of As. However, the total As in food can not exactly reflect the toxicity of As, while As speciation closely relates to the As bio-toxicity. Inorganic arsenic is verified as the carcinogen based on human epidemiological data. This paper reviewed the As species in edible plants, their bio-toxicity, and analytical methods.

Application of ³¹P nuclear magnetic resonance technology in the study of phosphorus fractions and their translocation and transformation in sediments: A review.

2010, 21(07):  1892-1898. 

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Phosphorus (P) release from sediments is one of the most important causes of lake eutrophication, while the activity of P is determined by P chemical
form. Due to its advantages in improving our knowledge about the P fractions in environmental samples, the ³¹P nuclear magnetic resonance (³¹P NMR) technology has received extensive attention. This paper summarized the current studies on the characterization, translocation, and transformation of P fractions in sediments by using this technology, and described the technical principles, classification, analytical procedures, and specific application fields of this technology. At present, the researches of sediment P by using ³¹P NMR technology were focused on the characterization of different P forms, the effects of microbes on the P translocation and transformation, and the quantitative analysis of different P fractions. The studies on the P-extracting agents and extraction methods were the hot topics as well. The potential issues and research trends about the application of ³¹P NMR technology in environmental samples were also discussed.