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Zhang F.,Xinjiang University | Tiyip T.,Xinjiang University | Feng Z.D.,Xinjiang University | Kung H..-T.,University of Memphis | And 6 more authors.
Land Degradation and Development | Year: 2015

The interaction between land use/cover change and landscape pattern is pivotal in research concerning global environmental change. This study uses three different Landsat images of 1989, 1998 and 2009 to study the land use/cover and landscape pattern changes in the middle reaches of the Tarim River basin. envi®, erdas®, ArcGIS® and fragstats® software were used to analyse the land use/cover changes. The objectives of study were to map and study the changes in land use/cover and landscape pattern, and propose some possible factors in making the land use/cover changes from 1989 to 2009. Seven different types of land use/cover are analysed, and the results are listed in tables. From 1989 to 1998, the percentage of farmland, slight-moderate saline land, heavy saline land and water areas have increased; woodland, desert and the undeveloped land have decreased. From 1998 to 2009, farmland, heavy saline land and the undeveloped land have increased; the other types of land use/cover have decreased. The gravity centre of each land use/cover types has shifted. The farthest shifting of the gravity centre was heavy saline land, which occurred between 1989 and 1998. The transformation and changes of land use/covers and landscape occurred more frequently from 1989 to 2009. Other types of land use and land cover changes to saline land have increased, which implied that a serious salinization took place in the Tarim Basin. The results from this study would show the adverse environmental changes (e.g. salinization and desertification) and they can be used for future sustainable management of land resources. © 2013 John Wiley & Sons, Ltd.

Gong L.,Xinjiang University | Gong L.,Key Laboratory of Oasis Ecology | Zhang H.,Xinjiang University | Zhang H.,Key Laboratory of Oasis Ecology | And 4 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2011

Cotton production plays an important role in the local economy of Xinjiang, China. According to traditional theory, long-term continuous cotton cropping will inevitably lead to unbalance in soil nutrients and diminish soil fertility. In 2008, soil samples, as 0 20 cm layers, were collected from native land (without cultivation, as a control) and five continuous cropping cotton fields, with different cultivation times (3, 8, 12, 20 and 30 years, respectively). Based on the analysis of seven physical and chemical properties: soil water content, bulk density, pH, organic matter, total N, available P, and available K, and five soil enzymatic activities: catalase, polyphenol oxidase, urease, invertase, and alkaline phosphatase, this study attempts to evaluate soil quality across continuous cropping cotton fields for different years in the Aler reclamation area of the upper reaches of the Tarim River. The soil quality assessment values (SQAV) were visualized using principal component analysis (PCA), and the soil quality grades were classified with a clustering diagram. The sustainable yield indexes (SYI) were calculated to verify the evaluated results. The results show that there are differences, in terms of the physical, chemical and enzymatic properties, between the continuous cropping cotton fields for the different years, and that continuous cropping of cotton has a significant influence on a number of soil properties. Soil quality initially increased, but then decreased gradually with continuous cropping. The soil quality in continuous cropping cotton fields at 8 and 12 years improved, but was degraded for 20 and 30 years. In the early stages, soil fertility increased through fertilization, irrigation and growth, and soil organic matter, nutrients and enzymatic activity subsequently rose, and soil quality improved. Cropped cotton fields at 3 years exhibited the lowest soil quality. Indicator values and the soil quality assessment values reached their maximum at 12 years. With continuous cotton cropping, soil quality gradually dropped in a monoculture pattern over a long period. Organic matter levels declined significantly, along with total N, polyphenol oxidase, invertase and alkaline phosphatase. Soil ecosystems undergo a series of degradation stages, and the soil texture was appeared to be transforming into brown desert soil. The soil quality assessment values decreased from 0.633 to 0.068 between 12 and 30 years. Different land use intensities and cropping patterns would significantly impact the soil quality, and extended cultivation for more than 10 years may also cause a decline in soil quality, to a varying degree, with unreasonable tillage practices. Soil quality values were consistent with sustainable yield indexes, but the latter lagged the former appreciably. Therefore, management practices need to consider increasing soil quality through irrigation, cotton- green manure usage, crop rotation and the combined application of organic and chemical fertilizers. This study could be beneficial for refining a sustainable agricultural development in the oasis. It is recommended that studies into the soil quality of arid lands be focused on defining a Minimum Data Set (MDS), with the aid of multivariate statistical techniques and an analysis of the relationships between different soil factors.

Yang F.,Xinjiang Institute of Ecology and Geography | Yang F.,University of Chinese Academy of Sciences | Yang F.,Research for Desert Grassland Ecosystem in Xinjiang | Wang X.,Xinjiang Institute of Ecology and Geography | And 4 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2012

In order to understand the morphological interactions between Tamarix ramosissima nebkhas and Tamarix ramosissima thickets in the oasis-desert ecotones, 100 independent Tamarix ramosissima nebkhas were randomly selected under different sand supply conditions in the northwest oasis-desert ecotone of Cele at the southern rim of the Taklimakan Desert. According to the difference in vegetation coverage and land surface characteristics, we divided the 100 nebkhas into four categories under four sand supply conditions (i. e. fixed sandy land, semi-fixed sandy land, semi-shifting sandy land and shifting sandy land), corresponding to poor, less poor, rich and richer sand supply conditions respectively. In field, the morphological parameters including the nebkhas' length, width, height, windward slope length and leeward slope length of nebkhas, together with thickets' height, length, width, crown area and different kinds of branch number were investigated. The results indicated that: (1) Increasing sand supply led to the increase of Tamarix ramosissima thickets' length (P = 0. 03), width (P = 0. 041), crown area (P = 0. 032), branch number (P = 0. 003), new branch rate (P = 0·002), rate of basal new branch (P = 0. 000) and biomass (P = 0. 001), while the plant height (P = 0. 929) retained invariable. The average values of these parameters were respectively 6. 85 m, 7. 23 m, 42. 14 m2, 418. 0, 49. 3%, 45. 0% and 65. 8 kg in shifting sandy land, which were the largest among the four sandy lands. (2) Tamarix ramosissima nebkhas' height (P = 0. 000), length (P = 0. 000), width (P = 0. 007), underside area (P = 0. 001), volume (P = 0·001) would significantly increase with sand supply enrichment. In shifting sandy land, the above corresponding average values of nebkhas' parameters were respectively 1. 83 m, 14. 16 m, 7. 93 m, 76. 64 m2 and 86. 33 m3, which were larger than the other lands. The nebkhas figure would develop into a long and narrow with the leeward slope becoming longer than the windward slope and the outline of sand dune tail would also become clearer. At this area most of nebkhas were still at a growing stage. The nebkhas in semi-shifting sandy land had the largest growth space, which's height would be near 4 m. (3) There were good morphological relationships among morphological parameters of Tamarix ramosissima nebkhas, the nebkhas length and width showed a coordinated growth trend with a quadratic polynomial regression equation in shifting sandy land, while a linear relationship in other sandy lands. There was a quadratic polynomial relationship between nebkhas underside area and height, and nebkhas volume increased linearly with the enlargement of underside area. (4) The Tamarix ramosissima thickets and nebkhas also exists good morphological correlation, among which the crown area and nebkhas volume showed a significant liner relationship. The adaptability mechanisms of Tamarix ramosissima nebkhas might be the stimulative function of comparative deep sand-burial as a result of wind accumulate with high-intensity to the growth of Tamarix ramosissima nebkhas and the feedback effect between the thickets and nebkhas. The conclusions indicated that the Tamarix ramosissima nebkhas in this area are the product of land degradation, and the semi-shifting sandy land is in a swift degeneration process now.

Zeng F.,Xinjiang Institute of Ecology and Geography | Zeng F.,Research for Desert Grassland Ecosystem in Xinjiang | Lu Y.,Xinjiang Institute of Ecology and Geography | Lu Y.,Research for Desert Grassland Ecosystem in Xinjiang | And 11 more authors.
Arid Land Research and Management | Year: 2013

One-year-old seedlings of Tamarix ramosissima Ledeb. and Alhagi sparsifolia Shap., two dominant species in the southern rim of the Taklamakan Desert, were investigated. A root uprooting and trench profile method were used to study the characteristics of the biomass distribution and root architecture. The results showed that the biomass distribution of two species differed. T. ramosissima had more biomass in the shoots, whereas A. sparsifolia had more biomass in the roots. The root architecture of two species differed, the root distribution of T. ramosissima resembled a "herringbone" formation in vertical profile, whereas the roots of A. sparsifolia were distributed in the form of a web, with dichotomous architecture. © 2013 Copyright Taylor and Francis Group, LLC.

Gui D.,Xinjiang Institute of Ecology and Geography | Gui D.,Chinese Academy of Sciences | Gui D.,Research for Desert Grassland Ecosystem in Xinjiang | Lei J.,Xinjiang Institute of Ecology and Geography | And 11 more authors.
Geoderma | Year: 2010

Soil particle-size distribution (PSD) is one of the most fundamental physical attributes of soil due to its strong influence on other soil properties related to water movement, productivity, and soil erosion. Characterizing variation of PSD in soils is an important issue in environmental research. Using ordination methods to characterize particle size distributions (PSDs) on a small-scale is very limited. In this paper, we selected the Cele River Basin on the north slope of the Middle Kunlun Mountains as a study area and investigated vegetation and soil conditions from 1960 to 4070. m a.s.l. Soil particle-size distributions obtained by laser diffractometry were used as a source data matrix. The Canonical Correspondence Analysis (CCA) ordination was applied to analyse the variation characteristics of PSDs and the relationships between PSDs and environmental factors. Moreover, single fractal dimensions were calculated to support the interpretation of the ordination results. Our results indicate that a differentiation of 16 particle fractions can sufficiently characterize the PSDs in CCA biplots. Elevation has the greatest effect on PSDs: the soil fine fractions increase gradually with increasing elevation. In addition, soil pH, water and total salt content are significantly correlated with PSDs. CCA ordination biplots show that soil and vegetation patterns correspond with one another, indicating a tight link between soil PSDs and plant communities on a small scale in arid regions. The results of fractal dimensions analysis were rather similar to CCA ordination results, but they yielded less detailed information about PSDs. Our study shows that ordination methods can be beneficially used in research into PSDs and, combined with fractal measures, can provide comprehensive information about PSDs. © 2010.

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