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06 June 2012, Volume 4 Issue 2 Previous Issue    Next Issue
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Research Articles
Periodical characteristics of baseflow in the source region of the Yangtze River
KaiZhu QIAN, Li WAN, XuSheng WANG, JingJing LV, SiHai LIANG
Journal of Arid Land. 2012, 4 (2): 113-122.   DOI: 10.3724/SP.J.1227.2012.00113
Abstract ( 3206 )     PDF (2218KB) ( 3119 )  
Baseflow, which represents the drainage of groundwater aquifers, is an essential component of runoff in hydrological basins. In the source region of the Yangtze River, the change of baseflow typically reflects the interactions between groundwater system and climatic factors in cold and arid areas. With modified Kalinen separation method, annual baseflow between 1957 and 2009 in this region was estimated and calculated. In comparison with the inner-annual variations of total streamflow, baseflow showed a weaker fluctuation. Before the 1980s, it was in a steady state; and after then, it demonstrated dramatic variations and large amplitudes. Based on the calculation results of baseflow, the real Morlet wavelet method was applied to reveal the periodical characteristics of baseflow as well as the precipitation and air temperature in the study area. It was found that annual baseflow has a 43-year trend as well as a 21-year period and a 7-year period. The 21-year period is most significant, with its wavelet coef-ficient having the largest fluctuation and amplitude. Summation of wavelet coefficients on these periods exhibits a similar change pattern with respect to that of annual baseflow. The summation curve takes a “W” shape, which means that the baseflow follows a four-stage sequence of descending–ascending–descending–ascending. As analyzed, the relationship among baseflow, precipitation and temperature is implied in the correlation between their normalized wavelet coefficients at different temporal scales. By the significant positive linear correlations both between precipitation and baseflow (correlation coefficient is 0.98) and between temperature and baseflow (correlation coefficient is 0.90) for the 43-year wavelet coefficients, it is suggested that the long-term increasing trends of precipitation and air temperature will lead to an increasing trend of baseflow. For wavelet coefficients of 21-year and 7-year periods, the positive linear correlation between precipitation and baseflow is significant. However, the correlation between air temperature and baseflow is not so evident, especially for the 21-year period. As a conclusion, correlation analysis with normalized wavelet coefficients showed that the change of annual baseflow was contributed mostly by the change of precipitation and secondly by the change of temperature.
Simulation of groundwater table dynamics based on Feflow in the Minqin Basin, China
Lan MA, XiaoMei WEI, AnMing BAO, ShiFei WANG
Journal of Arid Land. 2012, 4 (2): 123-131.   DOI: 10.3724/SP.J.1227.2012.00123
Abstract ( 3032 )     PDF (1192KB) ( 3664 )  
As groundwater table declination is an important factor resulting in degradation of eco-environment in the Minqin Basin, China, it is significant to investigate and understand the groundwater table dynamics in this area. According to the physical and geographical conditions of the Minqin Basin, a hydrogeological conceptual model and a mathematical model were established, and the mathematical model was figured out by using Finite Element subsurface Flow system (Feflow). Accurate hydrogeological parameters were acquired, and the spatio-temporal distribution dynamics of groundwater table for 1983–2001 were also simulated. The model performed well with a correlation coefficient of 0.977 and a mean error of 0.9768 m. The inflow and outflow of the groundwater system were predicted by time series analysis, and the groundwater table dynamics for 2011 were further acquired. Generally the groundwater table in the Minqin Basin would continue to decline. The groundwater table would decline during spring and summer irrigation, while it would rise during autumn-winter irrigation. The groundwater depression cones would expand with the increase of center depths. Therefore, regulatory measures should be taken to prevent the declination of groundwater table and improve the eco-environment of this area.
Effects of irrigation on precipitation in the arid regions of Xinjiang, China
Yong ZHAO, YongJie FANG, CaiXia CUI, AnNing HUANG
Journal of Arid Land. 2012, 4 (2): 132-139.   DOI: 10.3724/SP.J.1227.2012.00132
Abstract ( 3034 )     PDF (3708KB) ( 3158 )  
Soil moisture is an important parameter for the interaction between soil and atmosphere. It is the second important factor that influences climate change, next to sea surface temperature (SST). Most previous studies focused on the monsoon regions in East China, and only a few laid emphases on arid environments. In Xinjiang, which is located in Northwest China, the climate is typically arid and semi-arid. During the past 20 years, the precipitation in Xinjiang has shown a significant increasing trend, and it is closely related to oasis irrigation. This paper aims at discussing whether abnormal soil moisture in spring can be the signal to forecast summer precipitation. The effects of abnormal soil moisture due to farm irrigation in spring in arid environments on regional climate are investigated by using a regional climate model (RegCM3). The results indicate that positive soil moisture anomaly in irrigated cropland surface in May led to an increase in precipitation in spring as well as across the whole summer. The impact could last for about four months. The effects of soil moisture on the surface air temperature showed a time-lagging trend. The summer air temperature declined by a maximum amplitude of 0.8ºC. The increased soil moisture could enhance evaporation and ascending motion in the low troposphere, which brought in more precipitation. The soil moisture affected regional weather and climate mainly by altering the surface sensible and latent heat fluxes.
Differences in response of desert plants of different ecotypes to climate warming: a case study in Minqin, Northwest China
ZhaoFeng CHANG, ShuJuan ZHU, FuGui HAN, ShengNian ZHONG
Journal of Arid Land. 2012, 4 (2): 140-150.   DOI: 10.3724/SP.J.1227.2012.00140
Abstract ( 3274 )     PDF (719KB) ( 2637 )  
 Globally climates are warming. How do desert plants of different ecotypes respond to the climate change? This paper studied the differing responses to climate warming shown by desert plants of different ecotypes through analyzing the phenology and meteorological data of 22 desert plant species growing in Minqin Desert Botanical Garden in Northwest China during the period 1974–2009. The results indicate: (1) The temperature in the study area has risen quickly since 1974, and plants’ growing periods became longer. The spring phenology of mesophytes advanced, and the autumn phenology of xerophytes was delayed; (2) The starting dates of spring phenophase of mesophytes and xerophytes differed significantly and both showed an advancing trend; (3) The spring phenology of mesophytes advanced by more days than that of xerophytes, whereas the autumn phenology of mesophytes was delayed by less days than that of the xerophytes; and (4) Mesophytes are more sensitive than xerophytes to rising temperature in spring and falling temperature in autumn. These findings are of value in plant management and regional introduction of different species.
Effect of spatial scale and topography on spatial heterogeneity of soil seed banks under grazing disturbance in a sandy grassland of Horqin Sand Land, Northern China
XiaoAn ZUO, ShaoKun WANG, XueYong ZHAO, WenJin LI, Johannes KNOPS, Amy KOCHSIEK
Journal of Arid Land. 2012, 4 (2): 151-160.   DOI: 10.3724/SP.J.1227.2012.00151
Abstract ( 3300 )     PDF (2808KB) ( 2909 )  
Soil seed banks play an important role in the distribution and composition of plant communities in semiarid grassland ecosystems. However, information on how spatial scale influences the spatial heterogeneity of soil seed banks in a grassland under grazing disturbance is still lacking. Based on field sampling and greenhouse germination, we measured the species composition and seed density of soil seed banks at different spatial scales (30 m×30 m, 30 m×60 m and 30 m×90 m) along a topographical gradient in a sandy grassland in Horqin Sand Land, Northern China. By applying geostatistical methods, we examined how spatial scale and topography affected the spatial distribution of soil seed banks in the study area. Our results showed that the total number of species in soil seed banks, as well as the number of dominant annuals, increased with the increase of spatial scales. Seed density in soil seed banks decreased with the increase of spatial scales due to an increase in the slopes and relative heights of the sampling points. Geostatistical analysis showed that the relative structural variance (C/(C0+C)) of seed density and species richness were over 65% for all spatial scales, indicating that these variables had an obvious spatial autocorrelation and the spatial structured variance accounted for the largest proportion of the total sample variance. Spatial autocorrelation of seed density in soil seed banks increased with the increase of measured scales, while that of species richness showed a reverse trend. These results suggest that the total number of species in soil seed banks is spatial scale dependent and lower topography may accommodate more seeds. Spatial distribution of seed density in soil seed banks is also scale dependent due to topographic variation. Grassland management, therefore, needs to consider local grazing disturbance regime, spatial scale and topography.
Allometric response of perennial Pennisetum centrasiaticum Tzvel to nutrient and water limitation in the Horqin Sand Land of China
Wei MAO, TongHui ZHANG, YuLin LI, XueYong ZHAO, YingXin HUANG
Journal of Arid Land. 2012, 4 (2): 161-170.   DOI: 10.3724/SP.J.1227.2012.00161
Abstract ( 3363 )     PDF (732KB) ( 2447 )  
Optimal partitioning theory (OPT) suggests that plants should allocate relatively more biomass to the organs that acquire the most limited resources. The assumption of this theory is that plants trade off the biomass allocation between leaves, stems and roots. However, variations in biomass allocation among plant parts can also occur as a plant grows in size. As an alternative approach, allometric biomass partitioning theory (APT) asserts that plants should trade off their biomass between roots, stems and leaves. This approach can minimize bias when comparing biomass allocation patterns by accounting for plant size in the analysis. We analyzed the biomass allocation strategy of perennial Pennisetum centrasiaticum Tzvel in the Horqin Sand Land of northern China by treating samples with different availabilities of soil nutrients and water, adding snow in winter and water in summer. We hypothesized that P. centrasiaticum alters its pattern of biomass allocation strategy in response to different levels of soil water content and soil nitrogen content. We used standardized major axis (SMA) to analyze the allometric relationship (slope) and intercept between biomass traits (root, stem, leaf and total biomass) of nitrogen/water treatments. Taking plant size into consideration, no allometric relationships between different organs were significantly affected by differing soil water and soil nitrogen levels, while the biomass allocation strategy of P. centrasiaticum was affected by soil water levels, but not by soil nitrogen levels. The plasticity of roots, leaves and root/shoot ratios was ‘true’ in response to fluctuations in soil water content, but the plasticity of stems was consistent for trade-offs between the effects of water and plant size. Plants allocated relatively more biomass to roots and less to leaves when snow was added in winter. A similar trend was observed when water was added in summer. The plasticity of roots, stems and leaves was a function of plant size, and remained unchanged in response to different soil nitrogen levels.
Study of variegated and white flower petals of Capparis spinosa expanded at dusk in arid landscapes
Journal of Arid Land. 2012, 4 (2): 171-179.   DOI: 10.3724/SP.J.1227.2012.00171
Abstract ( 2939 )     PDF (692KB) ( 2560 )  
 In this study, we provide the first evidence of two pairs of petals of the rapidly expanded and short-lived nocturnal flowers of Capparis spinosa L. (caper) during the prolonged drought period in Eastern Mediterranean region. The corolla of the winter-deciduous, perennial C. spinosa consists of two pairs of petals: a pair of white dis-tinct petals and a pair of connate variegated petals with green basal parts. The results indicated the presence of substantially different amounts of chlorophyll in the two pairs of petals, while their carbohydrates’ content is comparable with that of the green sepals. High resolution imaging of petal surfaces of short-lived flowers of C. spinosa, obtained by using scanning electron microscopy, revealed stomata on the adaxial epidermis on both the white and the green parts of the variegated petals; while dense hairs were found on the surface of the abaxial green parts of the variegated petals. Adaxial, epidermal cells of the variegated petals, viewed using atomic force microscopy, possess a submicron, cuticular microfolding that differs between the white and the green parts of the petals. It appears that microridges on the adaxial, white parts of petals of C. spinosa compensate for an increase in cell surface area of the short lived petals, while the roughness of the green parts of petals was found to be higher than that of the white parts. Thus, the micromorphology of surfaces of epidermal cells is expected to affect optical properties and wettability of the floral tissues. These findings may be particularly important for understanding the performance of the short-lived petals of C. spinosa, which are exposed to dryland environments.
Molecular phylogeny of tribe Atraphaxideae (Polygonaceae) evidenced from five cpDNA genes
YanXia SUN, MingLi ZHANG
Journal of Arid Land. 2012, 4 (2): 180-190.   DOI: 10.3724/SP.J.1227.2012.00180
Abstract ( 3470 )     PDF (175KB) ( 3766 )  
Traditionally, Atraphaxis, Calligonum, Pteropyrum and Parapteropyrum are included in the tribe Atraphxideae. Recently, sequence data has revealed that this tribe is not monophyletic. The structure of the tribe was examined by adding more taxa and sequences to clarify the congruence between morphology and molecular phylogeny, the systematic placements of four genera in Polygonaceae, as well as the infra-generic relationships of Atraphaxis and Calligonum within Atraphaxideae. Five chloroplast genes, atpB-rbcL, psbA-trnH, trnL–trnF, psbK-psbI, and rbcL of Atraphaxis, Calligonum, Pteropyrum, and Parapteropyrum were sequenced. The non-monophyly of Atraphaxideae was confirmed. Atraphaxis and Calligonum, respectively, formed a monophyletic group that was well supported. Calligonum is closely related to Pteropyrum; Atraphaxis is sister to Polygonum s. str.; and Parapteropyrum is allied with Fagopyrum. Although the morphology suggested the four genera should form a tribe, the molecular data indicated Atraphaxideae was not one monophyletic group. The clades identified within Atraphaxis corresponded well with the current sectional classification based on morphological features. As for Calligonum, Medusa was identified as a non-monophyletic section
Winter habitat use of snow leopards in Tomur National Nature Reserve of Xinjiang, Northwest China
Feng XU, Ming MA, WeiKang YANG, David BLANK, YiQun WU, Thomas MCCARTHY, Bariusha MUNKHTSOG
Journal of Arid Land. 2012, 4 (2): 191-195.   DOI: 10.3724/SP.J.1227.2012.00191
Abstract ( 3517 )     PDF (395KB) ( 2827 )  
Snow leopards are one of the least known large cats, the population of which has dramatically de-creased. Their habitat loss was considered the main reason for the decline during the last decade, but their habitat preferences are still not well known. In this paper, we studied the winter habitat preferences of snow leopards in the Tomur National Nature Reserve (TNNR) in Northwest China during 2004–2005. We used sign surveys and transects to study the winter habitat selection of snow leopards. The results indicated that snow leopards showed a preference for habitat variabilities in slope aspect, vegetation cover, dominant topographical features, landform ruggedness and grazing status. We found that prey availability and dominant topographical features were the most important factors that determined the winter habitat selection of snow leopards. Our results supported the idea that the habitat preferences of snow leopards are a tradeoff between suitable habitat features and avoidance of potential human interactions.
Transdisciplinary research for supporting the integration of ecosystem services into land and water management in the Tarim River Basin, Xinjiang, China
Tuck-Fatt SIEW, Petra DoLL
Journal of Arid Land. 2012, 4 (2): 196-210.   DOI: 10.3724/SP.J.1227.2012.00196
Abstract ( 4136 )     PDF (230KB) ( 3404 )  
There is a growing need for both science and practice domains to collaboratively and systematically seek knowledge-based strategies for sustainable development. In recent years, transdisciplinary research has emerged as a new approach that enables joint problem solving among scientists and stakeholders in various fields. In this paper, we aim to introduce transdisciplinary research for supporting the integration of the concept of ecosystem services into land and water management in the Tarim River Basin, Xinjiang, Northwest China. While a large number of ecosystem service studies have helped to raise the awareness for the value of nature in China, a number of challenges remain, including an improved understanding of the relationships between ecosystem structure, functions and services, and the interaction of the various ecosystem services. A meaningful valuation of ecosystem services also requires the consideration of their strong spatial heterogeneity. In addition, ways to introduce the concept of ecosystem services into decision-making in China need to be explored. Thus, successful integration of the concept of ecosystem services into actual land and water management requires a broad knowledge base that only a number of scientific disciplines and stakeholders can provide jointly, via a transdisciplinary research process. We regard transdisciplinary research as a recursive process to support adaptive management that includes joint knowledge generation and integration among scientists and stakeholders. System, target, and transformation knowledge are generated and integrated during the process of (1) problem (re)definition, (2) problem analysis and strategy development, and (3) evaluation of the impact of the derived strategy. Methods to support transdisciplinary research comprise participatory modelling (actor-based modelling and Bayesian Networks modelling) and partici-patory scenario development. Actor-based modelling is a semi-quantitative method that is based on the analysis of problem perspectives of individual stakeholders as depicted in perception graphs. With Bayesian Networks, complex problem fields are modelled probabilistically in a simplified manner, using both quantitative data and qualitative expert judgments. These participatory methods serve to integrate diverse scientific and stakeholder knowledge and to support the generation of actually implementable management strategies for sustainable development. For the purpose of integrating ecosystem services in land and water management in the Tarim River Basin through trans-disciplinary research, collaboration among scientists and institutional stakeholders from different sectors including water, agriculture, forestry, and nature conservation is required. The challenge is to adapt methods of transdisciplinary research to socio-cultural conditions in China, particularly regarding ways of communication and decision-making.
The qanats of Xinjiang: historical development, characteristics and modern implications for environmental protection
WenJun HU, JieBin ZHANG, YongQiang LIU
Journal of Arid Land. 2012, 4 (2): 211-220.   DOI: 10.3724/SP.J.1227.2012.00211
Abstract ( 3658 )     PDF (343KB) ( 5452 )  
In China, qanats (kan’erjing/karez) exist only in Xinjiang Uygur autonomous region, being one form of traditional irrigation technology that made great contributions to oasis civilizations. There are different opinions on the origin and date of the qanats in Xinjiang due to a lack of adequate evidences. And uncontrolled over-exploitation of groundwater by pumping wells, as well as the expansion of surface water interventions nowadays, has caused serious impacts on not only the qanats, but also local ecological environments. There exist long-time arguments on whether the qanats should be restored or preserved. This study aimed to examine the historical development, geological conditions and characteristics, and modern implications of the qanats for oasis environmental protection, and to discuss the initiatives taken by local governments. The whole Xinjiang Uygur autonomous region was included as the study area, with a specific focus on Turpan prefecture. The materials and data were obtained from literature review and governmental documentation. Based on a systematic examination of three prevailing theories on the origination of Xinjiang’s qanats, it is suggested modern archaeological techniques could be good solutions to explore the origination in addition to historical records used normally. Although qanats fail to fully meet today’s enormous water demands, their rich historical, cultural, ecological and environmental implications in arid areas should not be underestimated. As a cultural heritage and ecologically-friendly engineering creation, qanat systems shall be kept in good condition and function by a valuable number. Recent initiatives to protect and restore target qanat systems in Xinjiang could provide positive examples for the practices in other regions of the world where the protection and restoration of qanats or similar technologies are desired.
Interactions between water-land resources and oasis urban development at the northern slopes of the Tianshan Mountains, Xinjiang, China
Jun LEI, Wen DONG, Yu YANG, Jie LU, Thomas STERR
Journal of Arid Land. 2012, 4 (2): 221-229.   DOI: 10.3724/SP.J.1227.2012.00221
Abstract ( 3397 )     PDF (390KB) ( 2628 )  
Urban development in arid and semi-arid regions is largely constrained by fragile physical environ-ments. The characteristics of an urban settlement are different from those in other regions of China. This paper analyses the coupling characteristics and spatio-temporal variations for oasis urban development and water-land resources at the northern slopes of the Tianshan Mountains by principal component analysis and a coupling degree model. The result shows that the degree and change in regional use of water and land resources are different among the studied cities/counties during their development. The built-up areas of these cities/counties have changed little with increasing populations and urbanization levels, which well reflects that the urban development in arid and semi-arid regions is limited by oasis areas. Per capita amount of water supplied, however, presented a trend of slowed growth with increasing levels of urbanization. Water consumption gradually increased with urban development and the improvement of people's living standards, accompanied by enhanced water use efficiency. The level of urbanization can be assessed through the coupling degree between oasis urban development and the use of water and land resources. A high coupling degree represents a high level of comprehensive urban development and use of water-land resources. Alternatively, a low coupling degree denotes a low level of urban development and water-land resource use.