Effects of spring fire and slope on the aboveground biomass, and organic C and N dynamics in a semi-arid grassland of northern China

The aboveground primary production is a major source of carbon(C) and nitrogen(N) pool and plays an important role in regulating the response of ecosystem and nutrient cycling to natural and anthropogenic disturbances. To explore the mechanisms underlying the effect of spring fire and topography on the aboveground biomass(AGB) and the soil C and N pool, we conducted a field experiment between April 2014 and August 2016 in a semi-arid grassland of northern China to examine the effects of slope and spring fire, and their potential interactions on the AGB and organic C and total N contents in different plant functional groups(C_3 grasses, C_4 grasses, forbs, Artemisia frigida plants, total grasses and total plants).The dynamics of AGB and the contents of organic C and N in the plants were examined in the burned and unburned plots on different slope positions(upper and lower). There were differences in the total AGB of all plants between the two slope positions. The AGB of grasses was higher on the lower slope than on the upper slope in July. On the lower slope, spring fire marginally or significantly increased the AGB of C_3 grasses, forbs, total grasses and total plants in June and August, but decreased the AGB of C_4 grasses and A.frigida plants from June to August. On the upper slope, however, spring fire significantly increased the AGB of forbs in June, the AGB of C_3 grasses and total grasses in July, and the AGB of forbs and C_4 grasses in August. Spring fire exhibited no significant effect on the total AGB of all plants on the lower and upper slopes in 2014 and 2015. In 2016, the total AGB in the burned plots showed a decreasing trend after fire burning compared with the unburned plots. The different plant functional groups had different responses to slope positions in terms of organic C and N contents in the plants. The lower and upper slopes differed with respect to the organic C and N contents of C_3 grasses, C_4 grasses, total grasses, forbs, A. frigida plants and total plants in different growing months. Slope position and spring fire significantly interacted to affect the AGB and organic C and N contents of C_4 grasses and A. frigida plants. We observed the AGB and organic C and N contents in the plants in a temporal synchronized pattern. Spring fire affected the functional AGB on different slope positions, likely by altering the organic C and N contents and, therefore,it is an important process for C and N cycling in the semi-arid natural grasslands. The findings of this study would facilitate the simulation of ecosystem C and N cycling in the semi-arid grasslands in northern China.

Strategic information perception methods and practices in the open source intelligence

Open source intelligence is one of the most important public data sources for strategic information analysis. One of the primary and core issues of strategic information research is information perception,so this paper mainly expounds the perception method for strategic information perception in the open source intelligence environment as well as the framework and basic process of information perception. This paper argues that in order to match the information perception result with the information depiction result,it conducts practical exploration for the results of information acquisition,perception,depiction and analysis. This paper introduces and develops a monitoring platform for information perception. The results show that the method proposed in this paper is feasible.

The Current Situation and Development Countermeasures of Creative Agriculture in Miyun

Creative agriculture,a new agricultural format formed by integrating agriculture,tourism and creative industries,is an important part of the urban modern agriculture. Proceeding from the functional position as an ecological conservation area,Miyun creative agriculture has obtained rapid growth,relying on its ecological resources,agricultural resources,tourist resources and leisure industry advantages. But there are still some problems. On the basis of analyzing the advantages and problems of creative agriculture in Miyun,the paper put forward the basic principles and thought pattern of developing creative agriculture in there. Besides,several countermeasures in terms of resources integration, scientific planning,exploring local cultural resources,developing theme products,constructing industrial chain,carrying out project design and creative planning,creating creative agricultural advantage brand are put forward.

Research on the Influence of Land Use Changing on Non-point Source Pollution in Heihe River Basin

Based on the exploring of SWAT model suitability in Hei River Basin, this paper analyze quantitatively and compare non-point source pollution loads occurred under different land use scene. At last, the following conclusion can be attained： （1） Land use change exerts tremendous influence on non-point source pollution. Since forest land can save water and reduce soil loss, which decreases greatly the source of non-point source pollution; （2） Strengthening land management and promoting reasonable land use, especially the over 15 degree slope farmland, will be the effective measure to control non-point source pollution and protect the quality of water in the Hei River basin; （3） The best land use situation in Hei River basin should be like the following modes： complying with national water source protection policy, gradual evacuation of river basin population, returning all the sloping farmland which is above 15 degree to forest land, allowing the existence of few farming land below 15 slope degree on the premise that the drinking water quality standard is reached, no unused land, good vegetation covering situation. At then, total nitrogen load is 13.25 kg, total phosphate load is 3.29 kg, which means it will not contaminate

Comparative Study of Isolated Polysaccharides from Triploid Poplar Using Different Solvents and Chemicals

The conversion of lignocellulose to value-added products is normally focused on fuel production;however,large-scale biorefineries require a cost-effective pretreatment process that can effectively fractionate the three main constituents of lignocellulose for the production of chemicals,fuels,and materials.In this study,a hemicellulosic biopolymer from poplar was fractionated by a mild organosolv process and the effects of various chemicals(sodium hydroxide,triethylamine,and formic acid)and alcohols on the fractionation efficiency and structural variation of hemicellulose were examined.Comparative studies indicated that an acidic catalyst decreased the purity of hemicelluloses by partial degradation of cellulose,and the core of the hemicellulosic biomacromolecule could be released and dissolved under alkaline conditions with 5.8%~19.0%yields.In addition,the use of alcohol with longer alkyl chains facilitated the release of the hemicellulosic biomacromolecule by partially cleaving the ether bonds in the lignincarbohydrate complex(LCC);this is probably due to steric hindrance.The thermal degradation behavior showed that complete pyrolysis was easily achieved for the hemicellulosic polymer with minimal branches irrespective of its molecular weight.

Preparation of Adsorbent with Magnesium Sulfate and Straw Pulp Black Liquor and Its Phenol Adsorption Properties

A magnesia adsorbent was prepared from straw pulp black liquor and magnesium sulfate for the first time, and its adsorption of phenol from aqueous solution was examined. The characteristics of the adsorbent were tested through chemical analysis, surface analysis, X-ray diffraction and FT-IR spectroscopy. The effects of various factors, such as dose, adsorption time and adsorption temperature, on phenol adsorption behavior were studied. The results show that the adsorption processes can be fitted to the isotherm Langmuir model very well. It was found that the adsorption process was strongly influenced by temperature and the optimal temperature for phenol removal was 40 ℃. The optimum adsorption time was 10 min, and desorption would happen afterwards. Between the models of Langmuir and Freundlich, the adsorption process of phenol onto magnesia fitted the Langmuir equation better.

Method and application of knowledge organization system for S&T literature

In the big data environment, the construction of massive S&T literature data resources needs intelligent technical assistance. With a focus on comparing the domestic and foreign knowledge organization systems and their applications, this article analyzes and summarizes the gaps in related researches and applications at home and abroad. A knowledge organization system framework for S&T literature data resources is presented in the article. Starting from the basic element of knowledge organization system, it also proposes and designs terminology-based analysis methods and technologies for S&T literature. Based on this framework, it proposes ideas and develops corresponding software tool to carry out relevant experiments. It gives an overview of theories and technologies method for future research.

Creating Inclusive Global Value Chains under the BRI from the Perspective of Public Goods Supply and Demand

Supply and demand of public goods provide a brand-new theoretical framework for research on the creation of inclusive global value chains(GVCs)under the Belt and Road Initiative(BRI).The supply of international public goods is an important positive variable for creating global value chains under the BRI,in which China and other developing countries involved,as well as their small and medium-sized enterprises(SMEs),are microscopic entities.When the BRI’s supply of instrumental,institutional,and conceptual international public goods is in equilibrium with the demand of GVC entities for public goods,the BRI creates necessary conditions for the extension of GVCs.GVCs created under the BRI are of great value in promoting inclusiveness,fair income distribution,balanced regional development,and the restructuring of international economic governance.Under the current GVC system,some developed countries have been wary about the BRI and even developed misgivings and biases.Nevertheless,developed countries may play an active role in bridging gaps in the BRI’s development and complement their respective strengths with developing countries for win-win cooperation.

System Variable Analysis on Development Stages of Urban Agriculture in Large Cities

China's urban agricultural development takes on stage evolution,and functional structure,customer structure,industrial organization,innovation activity,spatial form and industrial value of each stage has significant difference. Using the system variable analysis method,this paper established the urban agricultural development system including six types of functional variables. On the basis of summarizing stage characteristics,it analyzed reasons for stage characteristics focusing on four key variables,i. e. cost,efficiency,connection,and risk. Finally,it came up with recommendations for promoting China's urban agricultural development with the aid of stage development rules.

Solvability and thermal response of cellulose with different crystal configurations

Cellulose is a biodegradable and renewable natural material that it is naturally resistant to breaking and modification. Moreover, the crystalline structure of cellulose is a major factor restricting its industrial utilization. In this study, cellulose polymorphs were prepared from natural cellulose, and their solvability and thermal response were investigated. Using liquid- and solid-state NMR signals, the distinct types and dissolving states of cellulose polymorphs were identified. The thermal behavior of the polymorphic forms of cellulose-d was also evaluated, and cellulose Ⅱ exhibited the poorest thermal stability and a unique exothermic reaction.

Spirematospermum wetzleri (Heer) Chandler (Zingiberaceae) from the Miocene of Weichang, Hebei Province, North China and the phytogeographic history of the genus

Spirematospermum is a well-known extinct zingiberalean taxon, characterized by trilocular capsules containing many distinctive, spirally striate and arillate seeds. It is frequently found and studied in European Neogene carpological floras, but is scarcely represented in East Asia floras. In this work we recognize a new fossil record of Spirematospermum wetzleri（Heer） Chandler based on the capsules and seeds from the Miocene of Weichang, Hebei Province, North China. These fossils represent the first record of the species in the Miocene of China. Fossil data indicate that Spirematospermum probably originated in the Late Cretaceous of North America or Central Europe.The genus still existed in the Paleocene of North America, but became extinct after that time. However, the genus successively survived in Europe from the Eocene to Pliocene, and flourished luxuriantly during the Oligocene to Miocene. As there was Turgai Strait between Europe and Asia during the Eocene, the genus did not spread to Central Asia and West Siberia until the strait closed in the late Eocene/early Oligocene, and further expanded eastwardly to eastern Siberia, Russia, northern China and central Japan during the Miocene, but became extinct in Asia after the Miocene. The genus contracted its distribution to Europe in the Pliocene, and afterwards it became extinct in the world.

Pliocene taxodiaceous fossil wood from southwestern Ukraine and its palaeoenvironmental implications

Mineralized wood collected from Late Pliocene strata near Gorbki village in the Transcarpathian region of Beregovo Kholmogor’e in southwestern Ukraine was anatomically studied and identified.The wood possesses distinctive anatomical features and has distinct growth rings with an abrupt transition from early-to late-wood.Wood consists of tracheids with 1-3 seriate,dominating bi-seriate,opposite pits on the radial walls and taxodioid crossfield pitting,indentures present.Rays are uni-seriate and 1 to 73 cells high.Ray parenchyma horizontal walls thin and smooth.Axial parenchyma distributed in early-and late-wood and is solitary and diffuse,with end walls nearly smooth or slightly nodular.The combination of features observed in the wood indicates it belongs to the conifer family Taxodiaceae and is most similar to modern Sequoia and assigned to the fossil genus Sequoioxylon.Comparison with species of Sequoioxylon show it is most similar to Sequoioxylon burejense,but ray tracheids were not found in our specimens.We describe the specimens here as Sequoioxylon cf.s.burejense noting this similarity.Extant Sequoia is distributed in the northern California coastal forest eco-region of northern California and southern Oregon in the United States where they usually grow in a unique environment with heavy seasonal precipitation(2500 mm annually),cool coastal air and fog drip.This study supplies magafossil evidence of Sequoioxylon as an element of the Late Pliocene forest community in Ukraine and indicates a climate with heavy seasonal precipitation and fog drip.