نتایج جستجو برای: c 2007 influence of shrubs on soil chemical properties in alxa desert steppe
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methodology non-native participants in this study were sixty ba students majoring in english literature and teaching english as a foreign language at khayyam university of mashhad. they were senior students, between 21 to 24 years old, who had studied english for at least three and a half years and had passed several courses including grammar, reading, conversation, and writing. this was assum...
Soil microbial biomass and enzyme activities have an important influence on nutrient cycling. The temporal variation in soil microbial biomass C, N, and enzyme activities during the growing season were determined under three different alpine grasslands in Northern Tibet. The results showed that soil microbial biomass C, and N contents and enzyme activities of the alpine meadow (AM) and the alpi...
Precipitation change has significantly influenced annual net primary productivity (ANPP) at either annual or seasonal scales in desert steppes in arid and semi-arid regions. In order to reveal the process of precipitation driving ANPP at different time scales, responses of different ANPP levels to the inter-annual and intra-annual precipitation fluctuations were analyzed. ANPP was reversed by b...
Taking the mine dump in nonferrous metal as research object desert steppe Inner Mongolia, according to artificial remodeling of landforms and characteristics water soil erosion, vegetation restoration model tests on dumping site were carried out. The ecological effects four measures storage analyzed which including shrubs, shrubgrass, grass natural vegetation. results showed that compared with ...
In arid and semi-arid grassland, many models hypothesize that desertification leads to the replacement of grassland by shrubland vegetation; however, the theoretical interpretations are open to debate. Therefore, a field study was conducted in the Guinan desertified grassland of the Qinghai-Tibet plateau, North-west China, to test the hypotheses on a regional scale. We used four field sites to ...
to evaluate the effects of fertilizing and deficit irrigation regimes on some chemical properties of soil and plant, an experiment was conducted during 2007 and 2008 growing seasons. experimental design was a split plot based on a randomized complete block design with four replications. the treatments consisted of three deficit irrigation regimes (main plots) and six soil fertilizing systems (s...
The annual cycles of soil moisture and NO2 have been analysed across the climate zones of West Africa using two satellite data sets (OMI on AURA and ASCAT on MetOp-A). Exploring the sources and sinks for NO2 it is clear that the densely populated urban cities including Lagos and Abuja had the highest mean NO2 concentrations (>1.8 × 10 15 molecules cm -2 ) indicative of the anthropogenic urban e...
in this project, 4,4?-methylenebis(3-chloro-2,6-diethyl trimellitimidobenzene) as a diacid, was prepared by the reaction of trimellitic anhydride (tma) with 4,4?-methylenebis(3-chloro-2,6-diethylaniline) (mcdea). the novel poly(amide-imide) (pai) was synthesized from the reaction of 4,4?-methylenebis(3-chloro-2,6-diethyl trimellitimidobenzene) as a diacid with mcdea under green condition using ...
in this thesis, phosphorus ylides [phbppy], [no2bppy] and [brbppy] have been synthesized through the formation of phosphonium salt and dihydrogenation, followed by the reaction of pd(oac)2 and the orthopalladated dinuclear complexes [pd(?-cl)(phbppy)]2, [pd(?-cl)(no2bppy)]2 and [pd(?-cl)(brbppy)]2 have been produced. the reaction of dinuclear complexes and bidentate ligands [l = bipy (2,2-bipyr...
Knowledge of the distribution patterns of soil organic carbon (SOC) and factors that influence these patterns is crucial for understanding the carbon cycle. The objectives of this study were to determine the spatial distribution pattern of soil organic carbon density (SOCD) and the controlling factors in arid desert grasslands of northwest China. The above- and belowground biomass and SOCD in 2...
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