Current Issue

07 June 2011, Volume 3 Issue 2 Previous Issue    Next Issue
For Selected: View Abstracts Toggle Thumbnails
Research Articles
Limitations on the recruitment of the rare sand shrubby legume Eremosparton songoricum (Fabaceae) in Gurbantunggut Desert, China
DaoYuan ZHANG, HuiLiang LIU, Xiang SHI, JianCheng WANG, YongKuan ZHANG
Journal of Arid Land. 2011, 3 (2): 75-84.   DOI: 10.3724/SP.J.1227.2011.00075
Abstract ( 2355 )     PDF (313KB) ( 2537 )  
Eremosparton songoricum, a rare and endemic sand dune plant, appears to be experiencing recruitment failure. The structure of five populations from the Gurbantunggut Desert, China, was investigated for recruitment patterns, and two of them were examined for flowering, pollination and seed germination limits on regeneration. The results showed that total 150 seedlings only occurred on line transects in riverside Dure population, but they all died half a month later; no seedlings occurred in other four hinterland desert populations indicating recruitment was a failure at all populations although flowers were plentiful. Reproductive success depends on pollinators. Nectar is ‘reward’ for pollinators, with 0.06 μL–0.12 μL and 0.15 μL–0.35 μL per flower in Dure and Kabu populations, respectively, in continuously two secreting days. Spontaneous self pollination is rare with nearly zero fruit production. Geitonogamous self pollination is predominant with 14.47% fruit set. Seed mass in the riverside Dure population was significantly greater than that in other hinterland desert populations. Consequently, the Dure population exhibited a significantly higher germination rate (about 90%) than those in other populations (about 30%). Results suggested that recruitment failure of E. songoricum is not due to flower shortage, pollination limitation, or poor seed germination but environmental pressure and/or human disturbance.
Spatial distribution of vegetation and the influencing factors in Qaidam Basin based on NDVI
WenBin ZHU, AiFeng LV, ShaoFeng JIA
Journal of Arid Land. 2011, 3 (2): 85-93.   DOI: 10.3724/SP.J.1227.2011.00085
Abstract ( 5999 )     PDF (377KB) ( 6166 )  
The spatial distribution of vegetation in Qaidam Basin was analyzed using GIMMS (Global Inventory Modeling and Mapping Studies) / NDVI (Normalized Difference Vegetation Index) data set from January 1982 to December 2006. Based on the data of precipitation, terrain, stream systems, land use and the map of vegetation distribution in Qaidam Basin, we studied the factors influencing the spatial distribution of vegetation. The results showed that the vegetation was generally low in Qaidam Basin and there was a clear semi-ring structure from southeast to northwest. In some areas, the existence of rivers, lakes and spring belts turned this semi-ring structure into a non-continuous state and formed distinct bright spots and continuous linear features. There were four main factors that affected the spatial distribution of vegetation coverage in Qaidam Basin, i.e., precipitation, hydrological conditions, altitude and human activities. Precipitation and altitude have a correlation and determine the basic pattern of vegetation distribution in Qaidam Basin. The impacts of hydrological conditions and human activities were mainly embodied in partial areas, and often broke the pattern of vegetation distribution dominated by precipitation and altitude.
Response of vegetation to temperature and precipitation in Xinjiang during the period of 1998-2009
XiaoMing CAO, Xi CHEN, AnMing BAO, Quan WANG
Journal of Arid Land. 2011, 3 (2): 94-103.   DOI: 10.3724/SP.J.1227.2011.00094
Abstract ( 2967 )     PDF (988KB) ( 2772 )  
In this paper, 10-day spatio-temporal response of vegetation to the change of temperature and precipitation in spring, summer, autumn and whole year during the period of 1998―2009 was analyzed based on the data of SPOT VEGETATION-NDVI and 10-day average temperature or precipitation from 54 meteorological stations in Xinjiang. The results show that the response of 10-day NDVI to temperature was more significant than that to precipitation, and the maximal response of vegetation to temperature and precipitation lagged for two 10-day periods. Seasonally, the effect of temperature and precipitation on vegetation NDVI was most marked in autumn, then in spring, and it was not significant in summer. The response of vegetation to 10-day change of meteorological factors was positive with a long affecting duration in spring, and it had a relatively short affecting duration in autumn and summer. Spatially, the 10-day maximal response of NDVI to temperature in northern Xinjiang was higher than that in southern Xinjiang. The correlation between the 10-day NDVI in whole year and the temperature in the 0-8th 10-day period was significantly higher than that between the annual NDVI and the annual temperature at all meteorological stations; the interannual change of NDVI was accordant well with the change of annual precipitation. However, the effect of precipitation within a year on NDVI was not strong. The results indicated that interannual change of temperature was not the dominant factor affecting the change of vegetation NDVI in Xinjiang, but the decrease of annual precipitation was the main factor resulting in the fluctuation of vegetation coverage. Ten-day average temperature was an important factor to promote vegetation growth in Xinjiang within a year, but the effect of precipitation on vegetation growth within a year was not strong.
A cladistic scenario of Southern Pacific biogeographical history based on Nothofagus dispersal and vicariance analysis
Journal of Arid Land. 2011, 3 (2): 104-113.   DOI: 10.3724/SP.J.1227.2011.00104
Abstract ( 2563 )     PDF (253KB) ( 2315 )  
Nothofagus is regarded as a key group for interpreting Southern Pacific biogeographical history. Based on a molecular phylogenetic tree, a quantitative dispersal-vicariance analysis (DIVA) of the genus is presented. The results indicate that the ancestral area of Nothofagus is a broad realm almost including the total extant distribution pattern of the genus rather than a so-named center of origin. Integrated with the paleogeography, the time of origin and subsequent diversification is inferred to have started in the Late Cretaceous. Most vicariance and dispersal events should be contained in that period. Vicariance events versus dispersal events play a dominant rule in speciation. The dispersal events are hypothesized to happen from the Late Cretaceous to Eocene in terms of the geological history. Rich fossils are collected in the Eocene. South America, comprising three subgenera of Nothofagus, should be considered as a diversification region, in which the distribution of the species of subgenus Fuscospora and subgenus Nothofagus are explained by dispersal events during the Late Cretaceous-Late Eocene.
The formation age and evolution of Kumtagh Desert
JinNian TANG, ZhiZhu SU, Feng DING, ShuJuan ZHU, YouHao E, XinWei ZHAI, ZhiYu YI, HuJun LIU, JinChun ZHANG, FaMing LI
Journal of Arid Land. 2011, 3 (2): 114-122.   DOI: 10.3724/SP.J.1227.2011.00114
Abstract ( 2664 )     PDF (713KB) ( 2822 )  
The ancient aeolian sand has been regarded as an indicator for the formation and evolution of a desert in the past. Kumtagh Desert is located at the northern fringe of Qinghai-Tibet Plateau. The first integrated scientific investigation to the desert was carried out during the period of 2004-2006. Kumtagh Desert is an ideal natural model for studying the formation and evolution of the desert because the Quaternary strata containing ancient aeolian sands are widely distributed. The integrated field investigation and studies on sedimentary, chronology and palynology of typical profiles named Suosuo gully, Xiaoquan gully and gravel body with ancient aeolian sand layers showed that Kumtagh Desert was probably formed as early as 2,097.7±314.7 ka BP. During the period of 386.9±58.0 ka BP to 285.9±42.9 ka BP, the desert largely expanded and formed its modern distribution pattern. The desert was originally developed in the southwest, subsequently, expanded to the north and northeast. The sedimentary facies of Suosuo gully profile revealed that the desert experienced at least 19 cycles of advance and inverse processes of desertification with an average period of 110 ka in the Quaternary. The neotectonic movements played an important role in the formation, development and geomorphology of the desert. On one hand, the movements caused the formation of intermontane fault basin, which was further developed towards the closed drought basin, and caused the formation of natural environment. On the other hand, under the control of surrounding faults, the unique broom-shaped desert landscape was formed, and the gullies and sand ridges in this region experienced an abrupt directional change from north by west to north by east at the location of 39°45′-39°55′N. The unique landscape of gravel body that occurred widely in the northern desert was formed after 285.9±42.9 ka BP. The results in this paper provide the scientific basis for studying the formation age and evolutionary process under the dry climate and environment in the northwestern China, and the uplifting of Qinghai-Tibet Plateau as well as its responses to the global climate changes.
Evaluation of oasis stability in the lower reaches of the Tarim River
Chao LENG, YaNing CHEN, XinGong LI, YanXia SUN
Journal of Arid Land. 2011, 3 (2): 123-131.   DOI: 10.3724/SP.J.1227.2011.00123
Abstract ( 2798 )     PDF (374KB) ( 2861 )  
Oasis stability in the lower reaches of the Tarim River was assessed at the landscape scale (including changes in landscape pattern and land use in the oasis) and at the regional scale (including the cold-island effect and NDVI of the oasis) based on the methods of landscape ecology, GIS and Remote Sensing (RS). Thematic Mapping (TM) remote sensing images from 1990, 2000 and 2009 were employed along with the related meteorological and hydrological data pertaining to the reclamation area of the oasis in the lower reaches of the Tarim River. The results indicated that landscape heterogeneity and oasis complexity increased between 1990 and 2000. The comprehensive index of the degree of land use, the average index of the cold-island effect, NDVI value and oasis stability all decreased. However, the change trends in the indices referred to above were opposite between 2000 and 2009, and oasis stability was enhanced to some extent.
Impact of climate factors on runoff in the Kaidu River watershed: path analysis of 50-year data
XueMei LI, LanHai LI, LingPeng GUO, FeiYun ZHANG, Suwannee ADSAVAKULCHAI, Ming SHANG
Journal of Arid Land. 2011, 3 (2): 132-140.   DOI: 10.3724/SP.J.1227.2011.00132
Abstract ( 3719 )     PDF (398KB) ( 3111 )  
Runoff formation is a complex meteorological-hydrological process impacted by many factors, especially in the inland river basin. Based on the data of daily mean air temperature, precipitation and runoff during the period of 1958-2007 in the Kaidu River watershed, this paper analyzed the changes in air temperature, precipitation and runoff and revealed the direct and indirect impacts of daily air temperature and precipitation on daily runoff by path analysis. The results showed that mean temperature time series of the annual, summer and autumn had a significant fluctuant increase during the last 50 years (P?
GSPAC water movement in extremely dry area
HongShou LI, WanFu WANG, GuoBin ZHANG, ZhengMo ZHANG, XiaoWei WANG
Journal of Arid Land. 2011, 3 (2): 141-149.   DOI: 10.3724/SP.J.1227.2011.00149
Abstract ( 2619 )     PDF (405KB) ( 2315 )  
Under an extremely arid condition, a PVC greenhouse was built on the top of Mogao Grottoes in gobi area. The results of 235-day constant extraction of condensed water on the greenhouse film and soil water content showed that 2.1 g/(m2×d) groundwater moved up and exported into the soil, and a phreatic water evaporation existed in the extreme dry area where the groundwater is buried deeper than 200 m. After a prolonged export, the soil water content in the greenhouse was not lower but obviously higher than the original control ones. According to the monitored parameters including relative humidity and absolute humidity of soil, and temperature outside and inside the greenhouse, it was found that there is the available condition and mechanism for the upward movement of groundwater, and also it can be sure that the exported water was not from the soil and atmosphere outside the greenhouse. Phreatic water, an important source for soil water, interacts with atmosphere moisture via soil respiration. Soil salinity also has important effects on soil water movement and spatial-temporal heterogeneity. The extremely dry climate, terrestrial heat and change of upper soil temperature are the fundamental driving forces of water transportation and phreatic water evaporation in the Groundwater-Soil-Plant-Atmosphere Continuum (GSPAC) system.
Impact of aridization on soil cover transformation of the Aral Sea and the modern Syr-Darya Delta
Journal of Arid Land. 2011, 3 (2): 150-154.   DOI: 10.3724/SP.J.1227.2011.00150
Abstract ( 2201 )     PDF (183KB) ( 2605 )  
The effects of human activities on the soil cover transformation in the eastern part of Kazakhstan were investigated during the period of 1956-2008. The results of the research for different soil types in Priaralye indicated that there was 643.3×103 hm2 solonchaks, accounting for 38.5 % of the total area (1670.5×103 hm2) in 2008. Vast areas are occupied with dried lakeshore soil (311.1× 103?hm2), sandy soils (147.6×103 hm2) and grey-brown desert soils and solonetzes (146.7×103 hm2). In 2001 the area of solonchak was 755×103 hm2 and decreased to 643.3×103 hm2 in 2008, which due to the shrinkage of the Aral Sea, the areas of marsh and lakeshore solonchaks decreased with the increase of dried bottom of the Aral Sea. The level of soil cover transformation in the modern delta of the Syr-Darya River can be seen from the comparison of the results obtained from the different years in the study area. The area of solonchaks increased by 10×103 hm2 and the area of alluvial-meadow salinizied soils increased by 17.9×103 hm2 during the period of 1956–1969. It means that many non-salinizied soils were transformed into salinizied ones. Striking changes occurred in the structure of soil cover as a result of aridization. So, the researches in1969 significantly determined the areas of hydromorphic soils subjected to desertification (it was not fixed on the map before 1956). Later, these soils were transformed into takyr-like soils. The area of takyr-like soils increased almost by 3 times for 34 years (from 1956 to 1990). The long-term soil researches on soil cover transformation in Priaralye have shown that the tendencies of negative processes (salinization and deflation) are being kept and lead to further soil and eco-environment degradation in the region.