The effects of N-addition on litter mixture effects depend on decomposition time: A case from mixed-litter decomposition in the Gurbantunggut Desert.

Changes in nitrogen (N) deposition and litter mixtures have been shown to influence ecosystem processes such as litter decomposition. However, the interactive effects of litter mixing and N-deposition on decomposition process in desert regions remain poorly identified. We assessed the simultaneous effects of both N addition and litter mixture on mass loss in a litterbag decomposition experiment using six native plants in single-species samples with diverse quality and 14-species combinations in the Gurbantunggut Desert under two N addition treatments (control and N addition). The N addition had no significant effect on decomposition rate of single-species litter (expect Haloxylon ammodendron), whereas litter mass loss and decomposition rate differed significantly among species, with variations positively correlated with initial phosphorus concentration and negatively correlated with initial lignin concentration. After 18 months, the average mass loss across litter mixtures did not overall differ from those predicted from single species either in control or N addition treatments, that is, mixing of different species had no non-additive effects on decomposition. The N addition, however, did modify the direction of mixture effects and interacted with incubation time. Added N transformed synergistic effects of litter mixtures to antagonistic effects on mass loss after 1 month of decomposition, while transforming neutral effects of litter mixture to synergistic effects after 6 months of decomposition. Our results demonstrated that initial chemical properties played an important role in litter decomposition, while no effects of litter mixture on decomposition process in this desert region. The N addition altered the litter mixture effects on mass loss with incubation time, implying that increased N deposition in the future may have profound effects on carbon turnover to a greater extent than previously thought in desert ecosystems.

Research Progress in Quality Grading Standardization of Seed and Seedling in Chinese Materia Medica / 中国中医药信息杂志

The quality standardization of seed and seedling is not only the basis of standardized production of Chinese materia medica, but also the important content of standardization of Chinese medicine. To grade quality of seed and seedling and establish grading standards are an important part of seed and seedling standardization of Chinese materia medica. This article reviewed the recent research progress in the quality grading of seed and seedling in different types of Chinese materia medica, in order to provide a reference for further research and development.

Element Geochemistry of Lake Sediments from L07-10 in the "Great Ear" Area of Lop Nur and Its Significance for Climate Variation Change with ICP-OES.

Spectral analysis techniques were applied to geochemical element analysis to provide additional environmental data about evolution of salt lakes and climate change. The elements composition of lake sediments from L07-10 in the "Great Ear" Area of Lop Nur was analyzedby using Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES )and from 14 C carbon dating by using the EN accelerator mass spectrometry (AMS).This paper estimated the climate change in this region since 16.34 ka BP. Results demonstrate that the geochemical characteristics of major elements at all sediment levels can indicate environmental change sensitivity, and element composition is more sensitive to climate change. Overall, climate succession since 16.34 ka BP had been: warm-wet, warm-dry, cold-wet and warm-dry. From 8.09~6.34 ka BP，the climate obviously heated up and was warmer and drier, which is consistent with global and regional climate change estimates from other studies. By about 2 ka BP, the climate becomes warmer and drier and the water carrying capacity of this lake was reduced.

[Study on relationship between alfalfa canopy spectral reflectance and leaf water content].

In the present study, alfalfa canopy reflectance was researched at alfalfa squaring period under different irrigation amount at the hutubi county grassland ecological station. Determining the spectral diagnostic model of alfalfa leaf moisture content was determined by spectrometry. The results showed that (1) The spectral reflectance of alfalfa canopy gradually decreases with the increase in the leaf water content in the near infrared. (2) The spectral inversion model of alfalfa leaf moisture content established by normalized reflectance spectra is superior to the original reflectance spectra, and the prediction model established in the 1,344-1,660 nm band has the lowest average relative error (7.8%). (3) In this study, the spectral diagnostic model of the leaf moisture content is: Y=0.962 - 7.560X1451 + 5.295X1473. The spectral prediction model of the alfalfa leaf moisture content can provide a basis for decision making for scientific irrigation of alfalfa.

[Comparative analysis of endogenous hormones between two species of Ammopiptanthus seedlings around germination and under Pb2+ stress].

The changes in three endogenous hormones, phytohormones gibberrelic acid (GA3), indoles-3-acid (IAA) and abscisic acid (ABA), were studied around germination and under tress of different density of Pb2+ between two species of Ammopiptanathus. It was found that (1) around germination, in Xinjiang Ammopiptanthus the rate IAA decreased 77.80%, and the rate of ABA decreased 98.90%; and in Mongolia Ammopiptanthus the rate of IAA decreased 75.80%, the rate of ABA decreased 66.20%, and the GA3 contents in both had no big change. (2) With the increase in Pb2+ concentration (20-1 500 mg x L(-1)), the IAA decreased significantly; and only under the high density (more than 1 000 mg x L(-1)) of Pb2+, the GA3 was affected by it; the ABA did not change regularly. So the three endogenous hormone levels of Mongolia Ammopiptanthus were higher than those of Xinjiang Ammopiptanthus. (3) the distributions of Pb2+ in Ammopiptanthus seedlings are the root > stems > leaves. (4) the stress of high concentration of Pb2+ damages irreversibly the leaf cells of Ammopiptanthus. This study can provide the basis of reference data for further research on the growth characteristics, resilience and the mechanism of specific broad-leaved evergreen shrubs-Ammopiptanthus in desertification area.

[Analysis of the microelements contents in melons and fruits of Xinjiang].

Through the atom absorption and emission spectrum analysis, it is detected 8 trace elements contents in eleven species of melons and fruits in Xinjiang. On comparative analysis with biological standard of China, it is found that the zinc quantity in apples is 66.75 mg x kg(-1), the strontium quantity in jujubes is 8.62 mg x kg(-1) and Chinese-date contains strontium 8.62 mg x kg(-1) in Hetian area; and that in the Kuerle area the pomegranate is potassium 687 mg x kg, in Hami Territory Chinese-date contains manganese, zinc, strontium, calcium, iron, potassium and nickel, all of them are more over the national biological standard. The contents of copper in eleven species of melons and fruits are lower than the biological standard of China The average contents of 8 kind microelement in the pomegranate of Kuerle, in the apples of Hetian, the Chinese-date of Hami are very high (respectively to be 91.82, 121.5 and 275.3 mg x kg(-1)), and in the watermelon of Wujiaqu, the pericarp (54.19 mg x kg(-1)) take place higher than in the pulp (48.69 mg x kg(-1)) by 1.11 times. The result can provides the conference for studies of melons and fruits foodstuff studies in Xinjiang.