Biodiversity and invasibility: Distribution patterns of invasive plant species in the Himalayas,Nepal

Invasive plant species are exerting a serious threat to biological diversity in many regions of the world. To understand plant invasions this study aims to test which of the two plant invasiveness hypotheses; ‘low native diversity' vs. ‘high native diversity', is supported by the regional distribution patterns of invasive plant species in the Himalayas,Nepal. This study is based on data retrieved from published literatures and herbarium specimens. The relationship between invasive plant species distribution patterns and that of native plant species is elucidated by scatter plots, as well as by generalized linear models. The native plant species and invasive plant species have similar distribution patterns and the maximum number of invasive plant species is found in the same altitudinal range where the highest richness for native tree species is found. There is a clear trend of higher invasive plant richness in regions where native tree species richness is relatively high.Consequently, the native plant richness is highest in the central phytogeographic region, followed by the eastern and the western regions, respectively. The invasive plant species also follows a similar trend.Additionally, the invasive plant species richness was positively correlated with anthropogenic factors such as human population density and the number of visiting tourists. This study supports the hypothesis that ‘high native diversity' supports or facilitates invasive plant species. Further, it indicates that nativeand invasive plant species may require similar natural conditions, but that the invasive plant species seem more dependent and influenced by anthropogenic disturbance factors.     

Fresh snow chemistry from high mountain regions in central himalayas

Investigations of atmospheric composition in the Himalayas has been limited in both temporal and spatial scales, mainly due to difficult logistics. Ideal sites for monitoring atmospheric composition and its evolution should be free from local pollution and representative of the remote troposphere (HUEBERT et al., 1980). As the Himalayas are far removed from highly industrialized regions they provide suitable locations to monitor the chemistry of the remote troposphere and to study the evolu…     

THE SAND WEDGE AND MIRABILITE OFTHE LAST ICE AGE AND THEIR PALEOCLIMATICSIGNIFICANCE IN HEXI CORRIDOR

Sand wedge is formed under the conditions of coldclimate, and is an important basis for reconstructingpaleoenvironment (LI et al., 1990; WANG, 1991 ). Ithas been reported constantly over the last 20 years inthe Qinghai-Xizang (Tibet) Plateau (GUO, 1979; CUl,1983; XU et al., 1984; LIANG et al.,, 1984; PAN etal., 199 ) and North China (YANG et al., 1983; DONGet al., 1985) and Northeast China (GUO et al.,1981 ). We also found fossil sand wedge groups formedin the end of the Late P…     

AN OVERVIEW ON THE URBAN-RURAL INTERACTION IN THE PAST 50 YEARS IN CHINA

１ＩＮＴＲＯＤＵＣＴＩＯＮＢｙｄｅｆｉｎｉｔｉｏｎｕｒｂａｎｉｚａｔｉｏｎｉｓｔｈｅｐｒｏｃｅｓｓｏｆｒｕｒａｌａｒｅａｓｃｈａｎｇｉｎｇｉｎｔｏｕｒｂａｎａｒｅａｓｉｎｎａｔｕｒｅｆｏｒａｓｏｃｉ-ｅｔｙｉｔｉｓａｎａｔｕｒａｌｌｙｈｉｓｔｏｒｉｃａｌｐｒｏｃｅｓｓｏｆｔｈｅｔｒａｎｓｉｔｉｏｎｆｒｏｍａｔｒａｄｉｔｉｏｎａｌｒｕｒａｌｏｒａｇｒｉｃｕｌｔｕｒａｌｓｏｃｉｅｔｙｔｏａｍｏｄｅｒｎｉｚｅｄｕｒｂａｎｓｏｃｉｅｔｙＧＡＯ１９９１．Ｉｎｂｒｉｅｆｉｔｒｅｐｒｅｓｅｎｔｓａ…     

THE URBAN FUNCTION OF SUZHOU ON BASIS OF THE SHANGHAI-SUZHOU RELATIONSHIP

１ＩＮＴＲＯＤＵＣＴＩＯＮＷｉｔｈｔｈｅａｃｃｅｌｅｒａｔｉｏｎｏｆｔｈｅｅｃｏｎｏｍｉｃｇｌｏｂａｌｉｚａ-ｔｉｏｎｔｈｅｇｒａｄｕａｌｓｈａｐｉｎｇｏｆｔｈｅｎｅｗｉｎｔｅｒｎａｔｉｏｎａｌｄｉｖｉ-ｓｉｏｎｏｆｌａｂｏｒａｎｄｔｈｅｄｅｖｅｌｏｐｍｅｎｔｏｆｔｈｅｔｒａｎｓｎａｔｉｏｎａｌｃｏｒｐｏｒａｔｉｏｎｓｔｈｅｗｏｒｌｄｕｒｂａｎｓｙｓｔｅｍｓｈａｖｅｂｅｇｕｎａｎｅｗｒｏｕｎｄｏｆｉｎｔｅｇｒａｔｉｏｎ．Ｏｎｏｎｅｈａｎｄｔｈｅｃｉｔｉｅｓａｌｌｏｖｅｒｔｈｅｇｌｏｂｅａｒｅ…     

PRECIPITATION OF CALCIUM CARBONATE FROM SEAWATER

Slight perturbations of the oceanic DOC by addition of oxalic acid, tryptophan, and sodium humate did not affect the magnesium content of spontaneously precipitated Mg-calcites. However, the copresence of spontaneously precipitated aragonite and of Mg-calcite as a function of the initial degree of supersaturation was changed by the dissolved organic matter. Times of nucleation for carbonates was affected by organic matter at low organic concentrations because of coating and at high concentrations due to complexation.     

Effect of growth phase on the fatty acid compositions of four species of marine diatoms

The fatty acid compositions of four species of marine diatoms (Chaetoceros gracilis MACC/B13, Cylindrotheca fusiformis MACC/B211, Phaeodactylum tricornutum MACC/B221 and Nitzschia closterium MACC/B222), cultivated at 22 ℃±1 ℃ with the salinity of 28 in f/2 medium and harvested in the exponential growth phase, the early stationary phase and the late stationary phase, were determined. The results showed that growth phase has significant effect on most fatty acid contents in the four species of marine diatoms. The proportions of 16:0 and 16: 1n-7 fatty acids increased while those of 16 :3n-4 and eicosapentaenoic acid (EPA) decreased with increasing culture age in all species studied. The subtotal of saturated fatty acids (SFA) increased with the increasing culture age in all species with the exception of B13. The subtotal of monounsaturated fatty acids (MUFA) increased while that of polyunsaturated fatty acids (PUFA) decreased with culture age in the four species of marine diatoms. MUFA reached their lowest value in the exponential growth phase, whereas PUFA reached their highest value in the same phase.     

Current and thermohaline characteristics of the Arabian Sea during January 1998

Based on a ship survey during January 1998, the characteristics of the flow, the thermohaline properties and the volume transport of the Arabian Sea are discussed. A strong westward flow exists between 10.5?N and 11?N, part of which turns to the south as the Somali current near the coast at about 10?N and the rest turns north. At the passage between the African continent and the So- cotra Island, the northern branch separates into two flows: the left one enters the passage and the right one flows eastward along the southern slope of the island. Off the island the flow separates once more, most of it meandering northeast and a small fraction flow- ing southeast. Volume transport calculation suggests that the tidal transport is one or two orders of magnitude smaller than the total transport in this region and it becomes more important near the coast. The average velocity of the flow in the upper layer (0-150 m) is about 20 cm s-1, with a maximum of 53 cm s-1 appearing east of the Socotra Island, and the subsurface layer (200-800 m) has an aver- age velocity of 8.6 cm s-1; the velocity becomes smaller at greater depths. The depth of the seasonal thermocline is about 100 m, above which there is a layer with well mixed temperature and dissolved oxygen. High-salinity and oxygen-rich water appears near the surface of the northern Arabian Sea; a salinity maximum and oxygen minimum at 100 m depth along 8?N testifies the subduction of surface water from the northern Arabian Sea. Waters from the Red Sea and the Persian Gulf also influence the salinity of the area.     

CLOBAL CHARM OF THE CHANGJIANG RIVER DELTA

1SPLENDOROFHISTORICALCULTURE InChina,theChangjiang(Yangtze)RiverDelta①gen-erallymeansanadvancedproductivityandculture,whichaffectsdeeplynotonlythewholeChinabutal-sotheAsian-Pacificregion,evenEuropeandAfrica. 1.1CradlefortheCommunicationandPropagationofCivilization ThedevelopmentcourseoftheChangjiangRiverDelta'scultureisdevious,buttheNeolithicHemuduCultureexcavatedinYuyaoCityofZhejiangProvinceindicatestheadvancedpaddyriceculture;MajiabangCulture5000aB.P.andEastBridgeRuin…     

Detection of a new interstellar molecular ion, H2COH+ (protonated formaldehyde)

A new interstellar molecular ion, H2COH+ (protonated formaldehyde), has been detected toward Sgr B2, Orion KL, W51, and possibly in NGC 7538 and DR21(OH). Six transitions were detected in Sgr B2(M). The 1(1,0)-1(0,1) transition was detected in all sources listed above. Searches were also made toward the cold, dark clouds TMC-1 and L134N, Orion (3N, 1E), and a red giant, IRC + 10216, without success. The excitation temperatures of H2COH+ are calculated to be 60-110 K, and the column densities are on the order of 10(12)-10(14) cm-2 in Sgr B2, Orion KL, and W51. The fractional abundance of H2COH+ is on the order of 10(-11) to 10-(9), and the ratio of H2COH+ to H2CO is in the range 0.001-0.5 in these objects. The values in Orion KL seem to be consistent with the "early time" values of recent model calculations by Lee, Bettens, & Herbst, but they appear to be higher than the model values in Sgr B2 and W51 even if we take the large uncertainties of column densities of H2CO into account. We suggest production routes starting from CH3OH may play an important role in the formation of H2COH+.