Agronomic evaluation of polymer-coated urea and urease and nitrification inhibitors for cotton production under drip-fertigation in a dry climate

Interest in the use of enhanced-efficiency nitrogen (N) fertilizers (EENFs) has increased in recent years due to their potential to increase crop yield and reduce environmental N loss. Drip-fertigation is widely used for crop production in arid regions to improve water and nutrient use efficiency whereas the effectiveness of EENFs with drip irrigation remains unclear. A field experiment was conducted in 2015 and 2016 to examine the effects of EENFs on yield, N use and quality of cotton (Gossypium hirsutum) grown under drip-fertigation in arid NW China. Treatments included an unfertilized control and application of 240 kg N ha^-1 by polymer-coated urea (ESN), urea alone, or urea plus urease (NBPT) and nitrification (DCD) inhibitors. ESN was all banded in the plant row at planting, whereas urea was applied with 20% N banded at planting and 80% N by six fertigation events over the growing season. Results showed there was generally no treatment effect on seed and lint yield, N concentration or allocations, N recovery efficiency and fiber quality index of cotton. A lack of treatment effect could be due to N supplied with drip-fertigation better synthesized with crop N needs and the relatively high soil native NO₃^- availability, which hindered the effect of polymer-coated urea and double inhibitors. These results highlight the challenge of the employment of EENFs products for drip-fertigation system in arid area. Further research is required to define the field conditions under which the agronomic efficiency of EENFs products may be achieved in accordance with weather conditions.

Presence of spring-thaw N2O emissions are not linked to functional gene abundance in a drip-fertigated cropped soil in arid northwestern China

Spring-thaw represents a significant source for nitrous oxide (N₂O) emissions from fertilized croplands in temperate regions. In this study, we present surface N₂O fluxes, soil-profile N₂O concentrations at 5, 15, 30 and 60 cm depths along with the abundance of nitrifiers and denitrifiers over the winter and spring-thaw periods in an arid, drip- fertigated cotton field, which had received spring application of 240 kg N ha^-1 as urea alone (Urea), polymer-coated urea (ESN), and urea plus urease and nitrification inhibitors. Nitrous oxide emissions from December to April were generally unaffected by fertilizer treatments with a cumulative average of 186 g N ha^-1, accounting for 39% of the annual N₂O emissions. Emission peaks occurred at spring-thaw and coincided with increasing soil-profile N₂O concentrations at all depths, suggesting the burst in N₂O fluxes was due to new N₂O production, rather than a physical release of N₂O trapped in the soil profiles over winter. The abundance of nitrifier and denitrifier genes changed over the winter and spring-thaw periods but was not affected by fertilizer treatments from the previous spring, suggesting the abundance of N₂O-producing microorganism was more controlled by environmental conditions than N sources applied in the previous spring. The daily N₂O flux rate from December to April was positively correlated with soil temperature, water-filled pore space, and denitrifying enzyme activity, but not with the gene copy number of AOA, AOB, narG, nirS, nirK and nosZ, indicating that variation in the abundance of these genes was not contributing to the N₂O emissions. These results suggest that N₂O emissions in spring-thaw are substantial for drip-fertigated croplands in the arid regions and should be considered in the annual budgets. The environmental factors such as soil temperature and moisture are likely more important than the copy-numbers of N₂O-producing functional genes in driving the variability in spring-thaw emissions.

Manure application increased denitrifying gene abundance in a drip-irrigated cotton field

Application of inorganic nitrogen (N) fertilizer and manure can increase nitrous oxide (N₂O) emissions. We tested the hypothesis that increased N₂O flux from soils amended with manure reflects a change in bacterial community structure and, specifically, an increase in the number of denitrifiers. To test this hypothesis, a field experiment was conducted in a drip-irrigated cotton field in an arid region of northwestern China. Treatments included plots that were not amended (Control), and plots amended with urea (Urea), animal manure (Manure) and a 50/50 mix of urea and manure (U+M). Manure was broadcast-incorporated into the soil before seeding while urea was split-applied with drip irrigation (fertigation) over the growing season. The addition treatments did not, as assessed by nextgen sequencing of PCR-amplicons generated from rRNA genes in soil, affect the alpha diversity of bacterial communities but did change the beta diversity. Compared to the Control, the addition of manure (U+M and Manure) significantly increased the abundance of genes associated with nitrate reduction (narG) and denitrfication (nirK and nosZ). Manure addition (U+M and Manure) did not affect the nitrifying enzyme activity (NEA) of soil but resulted in 39–59 times greater denitrifying enzyme activity (DEA). In contrast, urea application had no impact on the abundances of nitrifier and denitrifier genes, DEA and NEA; likely due to a limitation of C availability. DEA was highly correlated (r = 0.70–0.84, P < 0.01) with the abundance of genes narG, nirK and nosZ. An increase in the abundance of these functional genes was further correlated with soil NO₃⁻, dissolved organic carbon, total C, and total N concentrations, and soil C:N ratio. These results demonstrated a positive relationship between the abundances of denitrifying functional genes (narG, nirK and nosZ) and denitrification potential, suggesting that manure application increased N₂O emission by increasing denitrification and the population of bacteria that mediated that process.

Role of surgical setting and patients-related factors in predicting the occurrence of postoperative pulmonary complications after abdominal surgery

OBJECTIVE

The aim of this retrospective study was to evaluate the role of surgical setting (urgent vs. elective) and approach (open vs. laparoscopic) in affecting postoperative pulmonary complications (PPCs) prevalence in patients undergoing abdominal surgery.

PATIENTS AND METHODS

After local Ethical Committee approval, 409 patients who had undergone abdominal surgery between January and December 2014 were included in the final analysis. PPCs were defined as the development of one of the following new findings: respiratory failure, pulmonary infection, aspiration pneumonia, pleural effusion, pneumothorax, atelectasis on chest X-ray, bronchospasm or un-planned urgent re-intubation.

RESULTS

PPCs prevalence was greater in urgent (33%) vs. elective setting (7%) (χ2 with Yates correction: 44; p=0.0001) and in open (6%) vs. laparoscopic approach (1.9%) (χ2 with Yates correction: 12; p=0.0006). PPCs occurrence was positively correlated with in-hospital mortality (Biserial Correlation r=0.37; p=0.0001). Logistic regression showed that urgent setting (p=0.000), Ariscat (Assess Respiratory Risk in Surgical Patients in Catalonia) score (p=0.004), and age (p=0.01) were predictors of PPCs. A cut-off of 23 for Ariscat score was also identified as determining factor for PPCs occurrence with 94% sensitivity and 29% specificity.

CONCLUSIONS

Patients undergoing abdominal surgery in an urgent setting were exposed to a higher risk of PPCs compared to patients scheduled for elective procedures. Ariscat score fitted with PPCs prevalence and older patients were exposed to a higher risk of PPCs. Prospective studies are needed to confirm these results.

Groundwater Depth Affects Phosphorus But Not Carbon and Nitrogen Concentrations of a Desert Phreatophyte in Northwest China

Ecological stoichiometry is an important aspect in the analysis of the changes in ecological system composition, structure, and function and understanding of plant adaptation in habitats. Leaf carbon (C), nitrogen (N), and phosphorus (P) concentrations in desert phreatophytes can be affected by different depths of groundwater through its effect on the adsorption and utilization of nutrient and plant biomass. We examined the biomass, soil organic C, available (mineral) N, and available P, and leaf C, N, and P concentrations of Alhagi sparsifolia grown at varying groundwater depths of 2.5, 4.5, and 11.0 m in 2015 and 2016 growing seasons in a desert-oasis ecotone in northwest China. The biomass of A. sparsifolia and the C, N, and P concentrations in soil and A. sparsifolia showed different responses to various groundwater depths. The leaf P concentration of A. sparsifolia was lower at 4.5 m than at 2.5 and 11.0 m likely because of a biomass dilution effect. By contrast, leaf C and N concentrations were generally unaffected by groundwater depth, thereby confirming that C and N accumulations in A. sparsifolia were predominantly determined by C fixation through the photosynthesis and biological fixation of atmospheric N2, respectively. Soil C, N, and P concentrations at 4.5 m were significantly lower than those at 11.0 m. Leaf P concentration was significantly and positively correlated with soil N concentration at all of the groundwater depths. The C:N and C:P mass ratios of A. sparsifolia at 4.5 m were higher than those at the other groundwater depths, suggesting a defensive life history strategy. Conversely, A. sparsifolia likely adopted a competitive strategy at 2.5 and 11.0 m as indicated by the low C:N and C:P mass ratios. To our knowledge, this study is the first to elucidate the variation in the C, N, and P stoichiometry of a desert phreatophyte at different groundwater depths in an arid ecosystem.

Which is the Easiest and Safest Technique for Central venous Access? A Retrospective Survey of more than 5,400 Cases

There is an ongoing debate on the technique for central venous catheterization associated with the lowest complication rate and the highest success rate. In an attempt to better define the easiest and safest venous approach, we have reviewed our 7-year experience with 5479 central venous percutaneous punctures (by Seldinger's technique) for the insertion of short-term (n=2109), medium/long-term (n=2627) catheters, as well as double-lumen, large-bore catheters for hemodialysis and/or hemapheresis (n=743). We have analyzed the incidence of the most frequent insertion-related complications by comparing seven different venous approaches: jugular vein, low lateral approach; jugular vein, high lateral approach; jugular vein, low axial approach; subclavian vein, infraclavicular approach; subclavian vein, supraclavicular approach; external jugular vein; femoral vein.

The results of our retrospective study suggest that the ‘low lateral’ approach to the internal jugular vein, as described by Jernigan and modified according to our protocol, appears to be the easiest and safest technique for percutaneous insertion of central venous access, being characterized by the lowest incidence of accidental arterial puncture (1.2%) and malposition (0.8%), no pneumothorax, and an extremely low rate of repeated attempts (i.e. more than two punctures before successful cannulation) (3.3%). We advocate the ‘low lateral’ approach to the internal jugular vein as first-choice technique for venipuncture in both adults and children, for both short-term and long-term central venous percutaneous cannulation.

Comparison of cholecystectomy and percutaneous cholecystostomy in acute cholecystitis: results of a retrospective study

OBJECTIVE

To retrospectively compare the clinical outcomes of percutaneous cholecystostomy (PC) and cholecystectomy in patients with acute cholecystitis admitted to an urban University Hospital.

PATIENTS AND METHODS

We studied 646 patients with acute cholecystitis. Ninety patients had placement of a PC at their index hospitalization, and 556 underwent cholecystectomy. Of the 90 patients with PC, 13 underwent subsequent elective cholecystectomy.

RESULTS

Overall, in-hospital mortality and postoperative complications were significantly higher in patients who received PC than in those who underwent cholecystectomy. In the ASA score 1-2 group, patients with PC were significantly older and had a longer postoperative stay while their mortality and morbidity were similar to patients who underwent cholecystectomy. In patients with ASA score of 3, PC and cholecystectomy did not differ significantly for demographic variables and clinical outcomes such as hospital stay, in-hospital mortality, postoperative complications and distribution of complications according to the classification of Clavien-Dildo. In mild, moderate, and severe cholecystitis, patients who underwent PC were significantly older than those who received cholecystectomy. In general, in mild, moderate and severe cholecystitis, the clinical outcomes did not differ significantly between patients who received PC and cholecystectomy. Morbidity was higher in patients with mild cholecystitis who underwent PC. Of the 77 patients dismissed from the hospital with drainage, 12 (15.6%) developed biliary complications and 5 needed substitutions of the drainage itself.

CONCLUSIONS

PC does not offer advantages compared to cholecystectomy in the treatment of acute cholecystitis. Its routine use is therefore questioned. There is need of an adequate, randomized study that compares PC and cholecystectomy in high-risk patients with moderate-severe cholecystitis.

Stoichiometry in aboveground and fine roots of Seriphidium korovinii in desert grassland in response to artificial nitrogen addition

Nitrogen (N) input by atmospheric deposition and human activity enhances the availability of N in various ecosystems, which may further affect N and phosphorus (P) cycling and use by plants. However, the internal use of N, P, and N:P stoichiometry by plants in response to N supply, particularly for grass species in a desert steppe ecosystem, remains unclear. In this work, a field experiment was conducted at an infertile area in a desert steppe to investigate the effects of N fertilizer addition rates on the stoichiometry of N and P in a dominant grass species, Seriphidium korovinii. Results showed that for both aboveground and fine roots of S. korovinii, N inputs exponentially increased the N concentration and N:P ratios while P concentrations decreased. Meanwhile, the relationships between N and P concentrations for both aboveground and fine roots were significantly negative. Furthermore, while the N concentrations in the plants were relatively low, P concentrations were higher than the global means, resulting in a relatively low N:P ratio. These results suggest that the stoichiometric characteristics of N were different from that of P for this desert plant species. Results also show that the intraspecific variations in the main element traits (N, P, and N:P ratios) were consistent at the whole-plant level. Our results also suggest that N should be part of any short-term fertilization plan that is part of a management strategy designed to restore degraded desert grassland. These findings highlight that nutrient addition by atmospheric N deposition and human activity can have significant effects on the internal use of N and P by plants. Therefore, establishing a nutrient-conservation strategy for desert grasslands is important.

Negative pressure wound therapy (NPWT) in duodenal breakdown fistulas: negative pressure fistula therapy (NPFT)?

OBJECTIVE

To describe for the first time in literature the specific methodology of use of negative pressure wound therapy (NPWT) for duodenal fistula through clinical cases. The constant increase of use of NPWT for complex surgical situations imposes tailored previously undescribed solutions for the technique.

PATIENTS AND METHODS

Herein, three cases of high output duodenal fistula successfully treated with Negative Pressure Wound Therapy (NPWT) are reported. The technical details for the application of NPWT to these fistulas are discussed and described.

RESULTS

All three patients recovered without the necessity of further surgical operations.

CONCLUSIONS

When using NPWT, management of high-output duodenal fistulas must rely on some degree of customization of the aspiration systems. The aim of the procedure is to put under depression the duodenal hole and surrounding tissues "all in one" and not to separate the complex wound in sectors as usually indicated. We suggest calling this technique Negative Pressure Fistula Therapy.

Linear and nonlinear characteristics of the runoff response to regional climate factors in the Qira River basin, Xinjiang, Northwest China

The inland river watersheds of arid Northwest China represent an example of how, in recent times, climatic warming has increased the complexity of Earth’s hydrological processes. In the present study, the linear and nonlinear characteristics of the runoff response to temperature and precipitation were investigated in the Qira River basin, located on the northern slope of the Kunlun Mountains. The results showed that average temperature on annual and seasonal scales has displayed a significantly increasing trend, but this has not been reflected in accumulated precipitation and runoff. Using path analysis, a positive link between precipitation and runoff was found both annually and in the summer season. Conversely, it was found that the impact of temperature on runoff has been negative since the 1960s, attributable to higher evaporation and infiltration in the Qira River basin. Over the past 50 years, abrupt changes in annual temperature, precipitation and runoff occurred in 1997, 1987 and 1995, respectively. Combined with analysis using the correlation dimension method, it was found that the temperature, precipitation and runoff, both annually and seasonally, possessed chaotic dynamic characteristics, implying that complex hydro-climatic processes must be introduced into other variables within models to describe the dynamics. In addition, as determined via rescaled range analysis, a consistent annual and seasonal decreasing trend in runoff under increasing temperature and precipitation conditions in the future should be taken into account. This work may provide a theoretical perspective that can be applied to the proper use and management of oasis water resources in the lower reaches of river basins like that of the Qira River.

Quiet PROPELLER MRI techniques match the quality of conventional PROPELLER brain imaging techniques

BACKGROUND AND PURPOSE

Switching of magnetic field gradients is the primary source of acoustic noise in MR imaging. Sound pressure levels can run as high as 120 dB, capable of producing physical discomfort and at least temporary hearing loss, mandating hearing protection. New technology has made quieter techniques feasible, which range from as low as 80 dB to nearly silent. The purpose of this study was to evaluate the image quality of new commercially available quiet T2 and quiet FLAIR fast spin-echo PROPELLER acquisitions in comparison with equivalent conventional PROPELLER techniques in current day-to-day practice in imaging of the brain.

MATERIALS AND METHODS

Thirty-four consecutive patients were prospectively scanned with quiet T2 and quiet T2 FLAIR PROPELLER, in addition to spatial resolution-matched conventional T2 and T2 FLAIR PROPELLER imaging sequences on a clinical 1.5T MR imaging scanner. Measurement of sound pressure levels and qualitative evaluation of relative image quality was performed.

RESULTS

Quiet T2 and quiet T2 FLAIR were comparable in image quality with conventional acquisitions, with sound levels of approximately 75 dB, a reduction in average sound pressure levels of up to 28.5 dB, with no significant trade-offs aside from longer scan times.

CONCLUSIONS

Quiet FSE provides equivalent image quality at comfortable sound pressure levels at the cost of slightly longer scan times. The significant reduction in potentially injurious noise is particularly important in vulnerable populations such as children, the elderly, and the debilitated. Quiet techniques should be considered in these special situations for routine use in clinical practice.

Vacuum Assisted Closure (VAC) therapyTM as a swiss knife multi-tool for enteric fistula closure: tips and tricks: a pilot study

OBJECTIVE

Enterocutaneous fistulas (ECFs) are an uncommon surgical problem, but they are characterized by a difficult management. Vacuum-assisted closure (VAC) therapy is a method utilized for chronic and traumatic wound healing. At first, VAC therapy had been contraindicated in the treatment of intestinal fistulas, but as time went by, VAC therapy revealed itself to be a "Swiss knife multi-tool". This paper presents some clinical cases of enterocutaneous (ECF) and enteroatmospheric fistulas (EAF) treated with VAC therapy™.

MATERIALS AND METHODS

The history of 8 patients treated for complex fistulas was revised. Four of them presented with enterocutaneous and four with enteroatmospheric fistulas. All were treated with VAC therapy with variations elaborated to help in accelerated closure of intestinal wall lesions.

RESULTS

Four out of four ECFs closed spontaneously. In the EAF group, in three cases the fistula turned slowly into an entero-cutaneous fistula, and in one out of four it closed spontaneously. The mean length of VAC therapy™ was 35.5 days and that of spontaneous closure was 36.4 days.

CONCLUSIONS

The results of our study encourage the use of VAC therapy™ for the treatment of enterocutaneous fistulas. VAC therapy™ use has a double therapeutic value: (1) it promotes the healing of the skin and allows also the management of EAFs; (2) in selected cases, those in which it is possible to create a deep fistula tract ("well") it is possible to assist to a complete healing with closure of the ECFs.

Observational study on preoperative surgical field disinfection: povidone-iodine and chlorhexidine-alcohol

BACKGROUND AND OBJECTIVES

Surgical site infection (SSI) rate is reported to range around 16%. Preoperative skin disinfection is keystone for SSI reduction. Chlorhexidine-alcohol has been reported to be more effective than Povidone-iodine (PVI). However, in many countries established habits and the inferior costs of PVI restrain the employment of chlorhexidine disinfection kits (ChloraPrep®) for the preparation of the surgical field.

MATERIALS AND METHODS

The costs of surgical field preparation in clean-contaminated surgery utilizing PVI (Betadine) and chlorhexidine alcohol and the evaluation of surgeon compliance and satisfaction, were studied by a observational study on 50 surgical operations in which surgical field was prepared with PVI checking established guidelines, and on 50 surgical operations in which chlorhexidine-alcohol (ChloraPrep) was employed. The use of auxiliary material was tabulated as well as the timing of the phases of disinfection and the surgeon's opinions.

RESULTS

The use of auxiliary material (gloves, gauzes, paper towels, surgical instruments, small swabs for umbilical cleaning) is associated with the type of disinfectant, with major use of auxiliary materials recorded in PVI disinfection. PVI disinfection does not follow stringent guidelines, in particular waiting for the disinfectant to dry. PVI guidelines are more demanding than those relative to ChloraPrep. The time necessary for the preparation of the field is significantly longer for PVI. Auxiliary material and guideline compliance must be taken into account when calculating costs; the former are direct costs (even though marginal) and the latter can determine major infective risk.

CONCLUSIONS

Chlorhexidine in kits is easier and faster to use than PVI, requires less auxiliary material and has been shown previously to reduce SSI in clean contaminated surgery.

Characteristics of the clonal propagation of Alhagi sparsifolia Shap. (Fabaceae) under different groundwater depths in Xinjiang, China

Clonal reproduction of plants commonly occurs in arid areas because seedling establishment is rare in such severe environments. The features of clonal architecture differ not only among plant species but also within the same species growing in different environments. The characteristics of clonal propagation of Alhagi sparsifolia Shap. (Fabaceae), growing on the margins of Cele Oasis on the southern rim of the Taklamakan Desert, were investigated in September 2010. The study was conducted on three sites with different groundwater depths (2.5, 4.5, and 11.0 m). The results showed that the root suckering depth and the ability to expand and the biomass of coarse lateral roots of A. sparsifolia significantly increased when the groundwater depth increased. Moreover, the vegetative regeneration capacity of A. sparsifolia significantly declined with increasing groundwater depth, and the canopy cover at the site with a groundwater depth of 2.5 m was significantly greater than at the other two sites. There was no difference in aboveground biomass at the three sites. In such hyper-arid environments with a scarcity of soil nutrients, it was demonstrated that groundwater depth plays an important role in the clonal growth and propagation traits of A. sparsifolia. Increases in the groundwater depth as a result of over-use of oasis water for irrigation could lead to reduced populations of this important species in the interfaces between oases and the surrounding desert.

An economic evaluation of Clostridium difficile infection management in an Italian hospital environment

BACKGROUND AND OBJECTIVES

Clostridium difficile infection (CDI) accounts for the majority of nosocomial cases of diarrhea, and with recent upsurge of multidrug-resistant strains, morbidity and mortality have increased. Data on clinical impact of CDI come mostly from Anglo-Saxon countries, while in Italy only two studies address the issue and no economic data exist on costs of CDI in the in hospital setting. A retrospective cross-sectional study with pharmacoeconomic analysis was performed on the CDI series of the Policlinico Gemelli of Rome, a major 1400 bed Hospital.

PATIENTS AND METHODS

The clinical charts of 133 patients in a 26 month period were reviewed. All costs of the involved resources were calculated and statistical analysis was carried out with means and standard deviations, and categorical variables as number and percentages.

RESULTS

The results show the significant sanitary costs of CDI in an Italian hospital setting. The cost analysis of the various elements (exams, imaging studies, therapies, etc.) shows that none independently influences the high cost burden of CDI, but that it is the simple length of hospital stay that represents the most important factor.

CONCLUSIONS

Prevention of CDI is the most cost-effective approach. The major break-through in cost reduction of CDI would be a therapeutical intervention or procedure that shortens hospital length of stay.

The new retained foreign body! Case report and review of the literature on retained foreign bodies in laparoscopic bariatric surgery

The advent of laparoscopic surgery has created a set of peculiar morbidities. As the laparoscopic devices, also the type of retained foreign bodies has changed. We present a case of unusual, apparently isolated and recurrent lung abscess, pleural effusion and poorly evident subphrenic abscess after laparoscopic gastric bypass, due to a retained Endo-Catch bag. A 27-year-old obese female underwent an uneventful laparoscopic Roux-en-Y gastric bypass. After surgery she developed a left basal lung abscess, that resolved in two weeks with heavy antibiotic therapy, while radiological abdominal imaging was apparently normal. Patient was discharged on p.o. day 30. After two months, she presented with fever and dyspnoea and no gastrointestinal complaints. Chest and abdominal computer tomography showed a left recurrent abscess with effusion but this time a 3 cm subphrenic mass with metallic clips inside was demonstrated on CT scan. Patient was treated with an explorative laparoscopy that identified an Endo-Catch bag with the jejunal blind loop inside. Postoperative left lung abscess can be a warning of a suphrenic surgical complication. Laparoscopic surgery requires even more attention to retained foreign bodies due to the reduced visibility of the surgical field. The recommendation to enforce recording of laparoscopic maneuvers is mandatory.

Spectral reflectance properties of major objects in desert oasis: a case study of the Weigan-Kuqa river delta oasis in Xinjiang, China

Aiming at the remote sensing application has been increasingly relying on ground object spectral characteristics. In order to further research the spectral reflectance characteristics in arid area, this study was performed in the typical delta oasis of Weigan and Kuqa rivers located north of Tarim Basin. Data were collected from geo-targets at multiple sites in various field conditions. The spectra data were collected for different soil types including saline-alkaline soil, silt sandy soil, cotton field, and others; vegetations of Alhagi sparsifolia, Phragmites australis, Tamarix, Halostachys caspica, etc., and water bodies. Next, the data were processed to remove high-frequency noise, and the spectral curves were smoothed with the moving average method. The derivative spectrum was generated after eliminating environmental background noise so that to distinguish the original overlap spectra. After continuum removal of the undesirable absorbance, the spectrum curves were able to highlight features for both optical absorbance and reflectance. The spectrum information of each ground object is essential for fully utilizing the multispectrum data generated by remote sensing, which will need a representative spectral library. In this study using ENVI 4.5 software, a preliminary spectral library of surface features was constructed using the data surveyed in the study area. This library can support remote sensing activities such as feature investigation, vegetation classification, and environmental monitoring in the delta oasis region. Future plan will focus on sharing and standardizing the criteria of professional spectral library and to expand and promote the utilization of the spectral databases.

Effects of cutting and burning on regeneration of Alhagi sparsifolia Shap. on the southern fringe of the Taklamakan Desert, North-west China

Indigenous vegetation such as Alhagi sparsifolia Shap. (Fabaceae) has been severely damaged in recent years because of the growing population and increasing land use on the southern margin of the Taklamakan Desert. Alhagi sparsifolia plays an important role in supporting the fragile ecosystem in the oasis foreland as it has multiple ecological and economic functions. Cele Oasis, located on the southern rim of the Taklamakan Desert, was used to investigate the impact of human disturbance on regeneration of A. sparsifolia in the oasis–desert ecotone. Observations of A. sparsifolia in response to cutting and burning were conducted in 2010 and 2011. The results showed that burning in spring significantly decreased height and biomass in comparison to cutting in the fall. Moreover, biomass was decreased by spring burning more than by spring cutting. Burning in spring is no advantage for the growth and survival of A. sparsifolia. Cutting in fall appears to be a useful treatment for increasing the production from and survival of A. sparsifolia that could facilitate the sustainable development of the Cele Oasis.

Distribution pattern of plant species diversity in the mountainous region of Ili River Valley, Xinjiang

In this paper, detrended canonical correspondence analysis was performed to analyze the relationships between diversity indices and environmental gradients, generalized additive model was employed to modal the response curves of diversity indices to the elevation, based on data from field investigation in the mountainous region of the Ili River Valley and a survey of 94 sample plots. Two hundred fifty-nine plant species were recorded in the 94 sample plots investigated, up to 235 species all appeared in the herb layer, and the species of woody plants were very limited. The communities with a complicated vertical structure presented higher values of indices. The distribution pattern of plant species diversity on the northern slope was affected by such factors as elevation, slope aspect, slope gradient, total nitrogen, total potassium, soil water content, organic matter, and that on the southern slope was mainly affected by such factors as slope gradient, elevation, available phosphorus, and soil water content. On the northern slope, Patrick index and Shannon-Wiener index of the plant communities presented a bimodality pattern along altitude; Simpson index and Pielou index showed a partially unimodal pattern. On the southern slope all the distribution pattern of species diversity indices showed two peaks, though Patrick index's bimodality pattern was not an obvious one. These altitudinal patterns were formed by the synthetic action of a variety of environmental factors with elevation playing an important role.