Authority in Charge: Chinese Academy of Sciences
Sponsored by: Xinjiang Institute of Ecology and
                    Geography, Chinese Academy of Sciences;
                    Soil Science Society of China
Editor in Chief: Lei Jiaqiang
Started in: 1984, Bimonthly
CN: CN 65-1095/X
ISSN: ISSN 1001-4675
Domestic Postal Code: 58-37
Foreign Postal Code: BM4927
15 August 2023, Volume 40 Issue 8 Previous Issue   
Weather and Climate
Statistics and analysis of surface raindrop spectrum characteristics in Liupan Mountain area of Ningxia
MA Simin, SHU Zhiliang, CHANG Zhuolin, ZHOU Nan, LIU Shijun
2023, 40 (8):  1203-1214.  doi: 10.13866/j.azr.2023.08.01
Abstract ( 96 )   HTML ( 10 )   PDF (8878KB) ( 77 )  

The microphysical parameters, average characteristics of raindrop spectra, and gamma distribution parameters of three types of rainfall (stratiform, cumulonimbus, and stratocumulus) were analyzed using raindrop spectrum data from different stations of 58 rainfall processes in the Liupan Mountains from 2020 to 2021. The results are as follows: (1) The mean values for all microphysical parameters at each station were higher for cumulonimbus rainfall compared to stratocumulus and stratiform rainfall. In stratiform and stratocumulus rainfall, the mean diameter (Dave) and mode diameter (Dmode) were smaller at the top and bottom of the mountain and greater on the mountainside. Conversely, the maximum diameter (Dmax), mass-weighted mean diameter (Dmode), rain rate (R), radar reflectivity (Z), and liquid water content (Q) increased with elevation on the east and west slopes. (2) The contributions of small raindrops to rain rate (R) and number concentration (N) were higher in stratiform and stratocumulus rainfall than in cumulonimbus rainfall. However, the contributions of small and medium-sized raindrops to N and R, respectively, were higher in cumulonimbus rainfall than in stratiform and stratocumulus rainfall. (3) The N0, μ, and λ parameters of gamma distribution decreased with an increase in altitude. The slope of the μ-λ fitting curve was closely related to the type of rainfall. (4) Compared with the foot of the mountain sites, the peak site exhibited a decrease in raindrop number concentration (Nw) and an increase in mean scale (Dm). (5) The characteristic diameter and microphysical parameters varied under different circulation situations.

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Radial growth response of Picea schrenkiana to climate change in the middle section of the northern slope of the Tianshan Mountains
ZHOU Xiaodong, CHANG Shunli, WANG Guanzheng, ZHANG Yutao, YU Shulong, ZHANG Tongwen
2023, 40 (8):  1215-1228.  doi: 10.13866/j.azr.2023.08.02
Abstract ( 66 )   HTML ( 5 )   PDF (9651KB) ( 48 )  

Analyzing the response of tree radial growth to climate change is crucial for accurately predicting the dynamic changes in forests in the future. The temperate coniferous forest, dominated by Picea schrenkiana, is widely distributed in the mid-mountain zone on the northern slope of the Tianshan Mountains. In this study, core samples of high-altitude Picea schrenkiana were collected, and the response characteristics of Picea schrenkiana radial growth to climatic factors and drought events were explored using tree-ring analysis. The results showed the following: (1) From 1960 to 2020, the tree-ring width index of Picea schrenkiana showed a significant upward trend without any growth recession, indicating favorable growth conditions in recent years. (2) The tree-ring width of Picea schrenkiana was mainly positively correlated with temperature from June to August, precipitation in April, and scPDSI in all months except July. Sliding correlation analysis showed an unstable relationship between tree-ring width and climatic factors. After 1991, the positive response of spruce to climatic factors was further strengthened. (3) The percentage of radial growth change in Picea schrenkiana was less than -25% from 1879 to 1880, indicating a growth decline from 1879 to 1885. An increase in drought frequency and intensity resulted in a decrease in the resistance and resilience of Picea schrenkiana to drought events. When Picea schrenkiana was in a relatively sufficient water environment for a long time and suffered from sudden drought events, it exhibited a significant decline in resistance and was prone to growth decline. In summary, under the influence of climate change, warming is still expected to promote the radial growth of high-altitude Picea schrenkiana in the region in the near future. However, the increase in the frequency and intensity of drought events during the warming process will further reduce the resistance and resilience of Picea schrenkiana, posing an increased risk of growth decline. In the near future, Picea schrenkiana will face the challenge of balancing growth promotion due to warming and growth inhibition due to drought. Further observation and research are required to understand the ultimate impact. In the future, various methods should be implemented to closely monitor the growth dynamics of Picea schrenkiana.

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Land and Water Resources
Comparative study on water area changes and influencing factors in the Guanting and Miyun reservoirs
MA Zhengang,LI Lili,ZHANG Jungui
2023, 40 (8):  1229-1239.  doi: 10.13866/j.azr.2023.08.03
Abstract ( 158 )   HTML ( 5 )   PDF (5090KB) ( 42 )  

This study focuses on the Guanting and Miyun reservoirs in the capital water conservation functional area to evaluate water area changes and analyze the impact of precipitation, vegetation coverage, and human water consumption since 1980. The study used long-term remote sensing images from 1980 to 2022 to extract the water area of each reservoir and calculate vegetation coverage. Pearson correlation analysis was used to explore the correlation between the three impact factors. We found that the water area of both reservoirs continuously increased, with historical highs since 2013, indicating significant water conservation achievements since the 18th National Congress of the Communist Party of China. In the past 40 years, the water area change process of the two reservoirs has significantly synchronized, with five different periods, including rising, high level maintenance, falling, ground feature maintenance, and recovery periods. There was no correlation between annual precipitation and reservoir area in the Zhangjiakou section upstream of the reservoir and also no correlation between precipitation and reservoir area in June and July during the same period. The vegetation coverage in the Zhangjiakou section upstream of the Guanting reservoir had an overall upward trend, with 2000 being a variation point. The vegetation coverage of the Zhangjiakou section upstream of the Miyun reservoir continues to stabilize at a level of 0.7. Correlation analysis shows that there is no correlation between vegetation coverage and reservoir water area. The artificial water consumption in the Zhangjiakou section of the Yongding River Basin decreased by 20 million m3 per year since 2000, showing a significant negative correlation with the water area of the Guanting reservoir and effectively increasing the inflow volume of the reservoir since 2019. The centralized water conveyance and water diversion from the Yellow River have had a significant impact on the water area of the Guanting reservoir and on ecological water replenishment along the river. Future research is needed to comprehensively evaluate the water conservation effectiveness of Zhangjiakou in terms of surface runoff into the reservoir, groundwater recovery, and ecological water replenishment.

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Application and comparison of two channel flood routing methods in Xinjiang mountainous areas
WANG Xiang, LYU Haishen, ZHU Yonghua, GUO Chenyu
2023, 40 (8):  1240-1247.  doi: 10.13866/j.azr.2023.08.04
Abstract ( 38 )   HTML ( 1 )   PDF (4820KB) ( 37 )  

We applied the two built-in channel routing methods of the WRF-Hydro model (i.e., the diffusive wave and the Muskingum-Cunge methods) to the upstream area of the Shimen Hydrological Station in the Hutubi River Basin and used GFS precipitation data for model input. The difference between the simulated and measured runoff was compared and analyzed using daily flow observations from 2015 to 2019 and annual average flow data from 1978-1983 and 2008-2019 at the Shimen Hydrological Station. We also discussed the simulation effect of the flood evolution method based on the WRF-Hydro model in the Xinjiang inland arid mountainous area. The results show that the simulation effect of the diffusive wave method is generally better than that of the Muskingum-Cunge method. This paper analyzes some characteristics of the two river routing models of WRF-Hydro to simulate floods. The diffusive wave method had better simulation results, but took longer, whereas the Muskingum-Cunge method had less ideal simulation results, but went faster.

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Effects of flood overflow on soil organic carbon and active components of Populus euphratica forest in the middle reaches of the Tarim River
MA Jilong, SHI Junhui, WANG Xinying, Aliya BAIDOURELA, LIU Maoxiu, Aijier ABULA
2023, 40 (8):  1248-1257.  doi: 10.13866/j.azr.2023.08.05
Abstract ( 38 )   HTML ( 2 )   PDF (2473KB) ( 28 )  

The ecological water transport of the Tarim River increases flood intensity on both sides of the basin, which has an important effect on the carbon cycle of the riparian Populus euphratica forest ecosystems. We studied the P. euphratica forest in the middle reaches of the Tarim River and the content changes of organic carbon and measured and analyzed the active components of the riparian P. euphratica forest at four different stages (1 m before (W1); 4 days after (W2); 17 days after (W3); and after (W4)). We found that the soil organic carbon (SOC) content was higher before and after overflow. The effect of flood overflow on the SOC content in the 0-20 cm soil layer was more significant than that of the 20-100 cm soil layer. During the same stage, the SOC content decreased with soil layer depth. The dissolved organic carbon (DOC) and microbial biomass carbon (MBC) in the 0-10 cm and 40-100 cm soil layers were significantly increased on the 4th day of the overflow compared to before the overflow. The contents decreased gradually with the extension of the overflow time. The differences between each stage were significant (P < 0.05). The DOC/SOC and MBC/SOC in the same soil layer differed significantly as time since the overflow extended (P < 0.05). The extracted organic carbon (EOC) content in the 0-10 cm soil layer before the overflow was higher than after the overflow. The EOC content in other soil layers during the overflow period was higher than before or after the overflow. The EOC/SOC in the 0-10 cm and 20-60 cm soil layers were significantly different at each overflow stage (P < 0.05). There was a significantly positive correlation between SOC and DOC content from before the overflow to day 17 of the overflow (r > 0.69, n = 15) and a significantly positive correlation between EOC and DOC content after discharge (r = 0.54, n = 15). There was a significant correlation between SOC and DOC content before the overflow and at various stages after the overflow. Based on the above analysis, the flooding process in the middle reaches of the Tarim River had a significant effect on the distribution of SOC and the active components of the riparian poplar forest, with differences found in the sensitive soil layers of each component. SOC was most significant in the 0-20 cm soil layer. DOC and MBC were most significant in the 0-10 cm soil layer and the 40-100 cm soil layer, respectively, and EOC was most significant in the 20-60 cm soil layer. Thus, the observed change regularity has the dual characteristics of forest and wetland.

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Prediction of soil salt content based on the random forest algorithm
LI Xiaoyu, JIA Keli, WEI Huimin, CHEN Ruihua, WANG Yijing
2023, 40 (8):  1258-1267.  doi: 10.13866/j.azr.2023.08.06
Abstract ( 44 )   HTML ( 2 )   PDF (14866KB) ( 53 )  

Soil salinization caused by natural and anthropogenic factors is an environmental hazard that is especially important in arid and semi-arid regions of the world. The accumulation of salts in soil is a major threat to crop production and global agriculture. Therefore, the rapid and precise detection of salt-affected lands is highly critical for sustaining soil productivity. This paper aims to analyze the performance of the random forest algorithm in mapping soil salinity in the Yinchuan Plain using Landsat-8 OLI, Sentinel-2A satellite images, and ground-based soil salt content (SSC) measurements with the aid of the Google Earth Engine (GEE) platform. We estimated SSC by establishing the relationship between spectral index characteristics and ground-measured soil salt content. The results show that GEE can provide reliable data support for soil salinity prediction. The random forest model established with Sentinel-2A as the data source performed better (R2 = 0.789, RMSE = 1.487) than and can therefore be used for the estimation of soil salinity using high-resolution remote sensing, which can provide theoretical support for large-scale soil salinity monitoring.

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Effects of different farmland shelterbelts on soil water and nutrient storage in the Hetao Irrigation District
JI Mingxin, FENG Tianjiao, XIAO Huijie, XIN Zhiming, LI Junran, WANG Dong
2023, 40 (8):  1268-1279.  doi: 10.13866/j.azr.2023.08.07
Abstract ( 42 )   HTML ( 4 )   PDF (11944KB) ( 37 )  

As an effective agricultural management method for improving ecological and environmental benefits, the farmland shelterbelt system is crucial in improving soil physical and chemical properties, the ecological environment, and crop yield. This study clarifies the effects of this system on ecosystem functions and provides a guide for the ecological restoration of fragile ecosystems. In the Hetao Irrigation District, three typical farmland shelterbelts (four-, five-, and eight-line patterns) were selected to measure soil properties at a 0-100 cm depth and vegetation properties of shelterbelts and farmland at different distances (0.3 H, 0.7 H, 1 H, 2 H, 3 H, and 4 H) from the shelterbelts during the growing seasons from 2019 to 2021. Soil moisture storage (SMS) and soil nutrient storage [soil carbon storage (SCS), soil nitrogen storage (SNS), and soil phosphorus storage (SPS)] were measured. The results showed that (1) the soil bulk density and clay content of different shelterbelts differed significantly in the horizontal direction, while the soil properties differed significantly in the vertical direction. (2) The shelterbelts had enhanced water retention and nutrient supply functions, and the soil water and nutrient reserves of the four-line pattern were higher than those of the five- and eight-line patterns (SMS = 237.44 mm; SCS = 544.93 g·m-2; SNS = 953.72 g·m-2; SPS = 859.04 g·m-2). (3) The average tree height and DBH of the four-row shelterbelt were 30.06 m and 0.41 m, respectively. Additionally, the four-row shelterbelt had the maximum crop yield of 15.75 t·hm-2. (4) Redundancy analysis showed that a close relationship existed between environmental factors and ecosystem functions in the different shelterbelts, soil characteristics were closely related to soil water and nutrient reserves, and vegetation attributes were negatively correlated with SNS and SPS. In conclusion, the four-line pattern demonstrated the strongest capacity for water and nutrient supply. The results of this study provide a sufficient theoretical basis for shelterbelt construction and ecological restoration in ecologically fragile areas.

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Plant Ecology
New records of Amaranthus in Xinjiang
WANG Chao, MA Zhancang, PAN Chengnan, WU Xingyue, SONG Wendan, YAN Ping
2023, 40 (8):  1280-1288.  doi: 10.13866/j.azr.2023.08.08
Abstract ( 29 )   HTML ( 1 )   PDF (12756KB) ( 22 )  

We found four new records of Amaranthus exotic weeds in Altay, Ili, Changji, Tacheng, and Hami during a field survey of weeds in northern and eastern Xinjiang. We recorded three species and one variety, respectively, of Amaranthus hybridus L., Amaranthus powelli S. Watson, Amaranthus viridis L., and Amaranthus retroflexus L. var. delilei (Richter & Loret) Thell that have not yet been found in this region. There are small populations of A. hybridus L. in Xinyuan, Yili, Urumqi, and Hami. A. viridis L. is only found in multiple populations in the Wusu Chepaizi reclamation area. A. retroflexus L. var. delilei (Richter & Loret) Thell. is only distributed in a small portion of Shihezi City. A. powellii S. Watson is only found in Balikun County, Hami City. The discovery of these newly recorded plants is of great significance to the study of the flora and species diversity of Amaranthus in Xinjiang, and also provides an important basis and new data for the study of their geographical distribution and of the spread and effective detection of invasive weeds. Specimens from the recorded species are kept in the Herbarium of Shihezi University.

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New records of mosses of Leskeaceae to Xinjiang
Gulistan ANWAR, Turgun NURDIN, Dilhumar ABDUKERIM, Mamtimin SULAYMAN
2023, 40 (8):  1289-1293.  doi: 10.13866/j.azr.2023.08.09
Abstract ( 29 )   HTML ( 1 )   PDF (9804KB) ( 12 )  

Based on the investigation and identification of bryophytes collected from Zhaosu County, West Tianshan Mountain, Xinjiang, one genus and two species of Leskeaceae new to Xinjiang are reported. They are Orthoamblystegium Dixon & Sakurai, Orthoamblystegium spurio-subtile (Broth. & Paris) Kanda & Nog. and Leskea scabrinervis Broth. & Paris. In this paper, the morphological characteristics, habitat and distribution were recorded for these two species. The microscopic structure photos of these two species were also provided.

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Syndynamic and diversity of species during gangue treatment in Shuanglong ditch
WANG Lide, SONG Dacheng, LI Guangyu, ZHAO Heran, ZHENG Kewen
2023, 40 (8):  1294-1303.  doi: 10.13866/j.azr.2023.08.10
Abstract ( 39 )   HTML ( 1 )   PDF (1270KB) ( 24 )  

In order to explore the succession and species diversity of plant communities in the process of gangue treatment, the text used the time-space substitution method to select the different years (2, 5, and 10 a) of gangue treatment in Shuanglong ditch, Tianzhu Tibetan Autonomous County, Gansu Province, and the untreated gangue as the contrast (CK) sample plots. The vegetation was surveyed, and the succession characteristics and species diversity of plant communities were analyzed. The results show that: (1) during the process of Shuanglong ditch gangue treatment, we identified 55 species of plants belonging to 40 genera and 24 families in 4 sample plots. Among these taxa, 15 families were single families, single genus, and single species. There were 28 species of Asteraceae, Poaceae, and Rosaceae, which accounted for 12.5% of the total number of families and 50.91% of the total species. Most of the species belonged to a few families, and most plant species belonged to a single family and a single genus. (2) During the years of gangue treatment, the dominant species of the community gradually changed from annual or perennial herbs to perennial herbs and shrubs. The number of plant species in the CK was 11, and after 5 years of gangue treatment, we identified 28 species, which decreased to 18 species after 10 years of gangue treatment. Finally, Elymus nutans, Poa pratensis, and Hippophae rhamnoides become the dominant species in the sample plot; and these three plants comprised 48.107. (3) With increasing gangue treatment time, the number of species, Shannon diversity index, and Margalef richness index gradually increased from CK to 5 years after gangue treatment, reaching maximum values of 28, 3.506, and 2.877 respectively. The Pielou evenness index changed little, although we observed a trend of “falling-rising-falling.” In contrast, the Simpson dominance index showed a trend of “rising-falling-rising,” reaching the maximum value of 0.359 after 10 years of gangue treatment. (4) The length of time of gangue treatment greatly impacted the quantitative characteristics of the plant population. Plant height significantly increased from CK, 2-10 a (P < 0.05). Coverage significantly increased from CK to 5 a and 10 a of treatment (P < 0.05). The number of plants increased significantly from CK to 10 a of treatment (P < 0.05). Overall, the results indicate that years of gangue treatment greatly impacted vegetation succession and species diversity in the Shuanglong ditch of the eastern section of Qilian Mountains; and the plant community has gradually become single and stable.

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Population structure and dynamic analysis of natural Juniperus rigida in a loess hilly area
SONG Jiajia, LI Gangtie, GUO Jingjie, GU Zhonghou, LIU Kun, LI Zhilong, KANG Xia
2023, 40 (8):  1304-1311.  doi: 10.13866/j.azr.2023.08.11
Abstract ( 37 )   HTML ( 0 )   PDF (1316KB) ( 18 )  

This study focused on the natural Juniperus rigida population in the loess hilly region of Inner Mongolia. The structure and dynamic changes of the population were analyzed using a static life table, survival function, dynamic quantitative analysis, and time series model. The results showed that the population mainly comprised many individual seedlings, followed by medium and less mature trees. Combined with the dynamic change index Vpi > 0, the population was a growth type. The survival curve was verified using the curve model and tended to Deevey-II, indicating that the mortality rate of each age class was stable. Considering the external interference, the dynamic index tended to 0, and the population growth is not obvious under the interference condition. In the survival function analysis, the population showed a strong survival trend in the early stage, followed by a gradual decline in the middle stage. During the 2-to-8-year period, the number of seedlings decreased while middle-aged and adult trees increased. The seedling stage is crucial to the regeneration and development of the population. Therefore, implementing scientific protection measures for seedlings to promote population regeneration is recommended. Research on the internal mechanisms of the Juniperus rigida population can enrich vegetation construction in arid areas, provide a reference for population management, and provide a theoretical basis for vegetation protection and restoration in the loess hilly area.

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Effect of environmental factors on the transpiration water consumption of various artificial arbor stands
LI Jiannan, SHI Haibin, MIAO Qingfeng, SHAN Dan, RONG Hao, WEN Yaqin
2023, 40 (8):  1312-1321.  doi: 10.13866/j.azr.2023.08.12
Abstract ( 34 )   HTML ( 0 )   PDF (3933KB) ( 16 )  

This study aims to explore the transpiration response of different artificial arbor stands to environmental factors in arid areas and provide a theoretical basis for selecting transplanted artificial vegetation and maintaining the ecological environment in mining areas. In this study, the EMS81 Sap flow meter stemflow monitoring system and Watch Dog soil moisture sensor were used to monitor trunk sap flow in artificial Populus tomentosa and Pinus tabulaeformis stands in the Shengli East No. 2 mining area of Xilinhot, as well as the soil moisture near their respective roots. Meteorological data from the local national meteorological station were incorporated to analyze the variations in transpiration between the Populus tomentosa and Pinus tabulaeformis stands. Stepwise regression modeling was employed to assess the transpiration of Populus alba and Pinus tabulaeformis stands across different months and various environmental factors. During the first ten days of May, Populus tomentosa and Pinus tabulaeformis exhibited similar change trends in daily transpiration. However, for the remaining period, Populus tomentosa exhibited a more intense change in daily transpiration than Pinus tabulaeformis. During the periods with no significant changes in soil moisture, the soil moisture content near the roots of Pinus tabulaeformis at depths of 30 cm, 50 cm, 70 cm, and 90 cm was significantly higher than that near the roots of Populus alba at the same depths. The maximum transpiration value of poplar stands and the corresponding soil water changes at different root depths were correlated in May, July, and September, while those of Chinese pine stands were correlated in June and August. The number of entry factors and the contribution rate of stepwise regression models varied across different time intervals. Under natural conditions, the changes in transpiration of Populus tomentosa and Pinus tabulaeformis stands in arid areas differ significantly between months and are affected to varying degrees by changes in soil moisture. Moreover, the soil water holding capacity of Pinus tabulaeformis roots was better than that of Populus tomentosa roots during periods of minimal or insignificant changes in soil water. Monthly stepwise regression provides an improved fit for stand transpiration.

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Ecology and Environment
Analysis of the spatiotemporal variation characteristics and driving factors of grassland vegetation cover in Ningxia based on geographical detectors
WEN Miaoxia, HE Xuegao, LIU Huan, ZHANG Jing, LUO Chen, JIA Fengming, WANG Yigui, HU Yunyun
2023, 40 (8):  1322-1332.  doi: 10.13866/j.azr.2023.08.13
Abstract ( 59 )   HTML ( 4 )   PDF (9532KB) ( 36 )  

This study aims to examine the spatiotemporal variation characteristics of grassland vegetation cover at the regional scale and analyze its driving factors. The findings will provide a scientific reference and decision-making basis for the scientific formulation of protection and restoration models, treatment measures, and the sustainable management of the grassland ecosystem in Ningxia, which are crucial for maintaining the balance of the regional grassland ecosystem and promoting ecological protection and high-quality development in the Yellow River Basin. In this study, the NDVI time series dataset of SPOT/VEGETATION (2000-2019) was used as the data source. The annual mean method, Theil-Sen Median trend analysis, and Mann-Kendall test were employed to study the spatiotemporal distribution and variation characteristics of grassland vegetation cover in Ningxia. Furthermore, the Hurst index method was used to analyze the sustainability characteristics and future development trends of grassland vegetation cover. Simultaneously, the influence of 13 factors, such as average precipitation, altitude, and gross domestic product, on the spatiotemporal distribution was quantified based on the geographical detectors approach. The results show that from 2000 to 2019, the average annual NDVI of vegetation in Ningxia grassland showed a fluctuating growth trend, with a growth rate of 0.005 per year. The regional fluctuation was quite different, with extremely high and high vegetation cover areas concentrated in the Liupan Mountains and the irrigation area along the Yellow River. Overall, the NDVI change showed a low to medium fluctuation trend, and the regional fluctuation was quite different. The vegetation cover condition improved significantly over the 20-year period, with a small degradation area and a favorable overall change trend. However, 59.341% of the grasslands are projected to face potential risks of continuous degradation or transformation from improvement to degradation in the future. The most sensitive environmental factor influencing grassland vegetation distribution response was precipitation, and climate and soil had the strongest interaction explanatory power overall. The relationship between the factors affecting the distribution and variation characteristics of grassland vegetation primarily manifested as mutual reinforcement or nonlinear enhancement, with no independent relationship between the factors. This study provides a scientific reference and decision-making basis for the sustainable management of the grassland ecosystem in Ningxia.

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Effects of human activities on carbon storage in the Irtysh River Basin
ZHANG Xiaomin, ZHANG Dongmei, ZHANG Wei
2023, 40 (8):  1333-1345.  doi: 10.13866/j.azr.2023.08.14
Abstract ( 44 )   HTML ( 1 )   PDF (9464KB) ( 39 )  

Carbon sequestration is among the main functions of terrestrial ecosystem services, and the carbon sequestration capacity of terrestrial ecosystems directly affects global carbon emissions and climate change processes. Human activities directly influence land use and cover change, consequently affecting the carbon sequestration function of ecosystems. The terrestrial ecosystem services in dry and cold regions are more vulnerable and significantly impacted by human activities. Therefore, utilizing land use data from the Irtysh River Basin in the Altai Mountains from 2000 to 2020, the InVEST model was used to estimate and analyze the spatial distribution of carbon stocks in the basin during different periods. Subsequently, the influence of human activities on the spatial distribution of carbon stocks was discussed. The results show the following: (1) The main land use types in the basin are woodland, grassland, and unused land, and the land use pattern changed significantly from 2000 to 2020. Cultivated land, urban and rural land, industrial and mining land, and residential land expanded continuously, increasing by 2619.35 km2 and 186.68 km2, respectively. Grassland and water areas initially decreased and then expanded, increasing by 4725.13 km2 and 33.47 km2, respectively. Meanwhile, forest land and unused land decreased continuously by 2328.88 km2 and 5237.76 km2, respectively. (2) During this period, the spatial distribution pattern of carbon stocks in the basin was similar and showed a zonal distribution. High-value areas were distributed in high-altitude regions where grassland and woodland were clustered, while low-value areas were distributed in low-altitude regions where unused land was clustered. In 2000, 2005, 2010, 2015, 2020 the total carbon storage in the basin was 641.60 Tg, 645.78 Tg, 646.83 Tg, 650.28 Tg, and 665.91 Tg, respectively, with an annual growth rate of 0.95%, showing an upward trend. (3) The areas in the basin where carbon storage decreased or increased showed a spot-like distribution. Furthermore, carbon storage reduction mainly occurred through the conversion of grassland to unused land and cultivated land, with an average annual reduction of 58.81 Tg. The increase in carbon storage primarily resulted from the conversion of unused land into cultivated land and grassland, with an average annual increase of 64.82 Tg. From 2000 to 2020, the net sequestration of carbon storage exceeded the net release, indicating an increasing carbon sequestration capacity in the Irtysh River Basin. Overall, the reclamation of land and grass due to human activities is the main reason for the increase in carbon storage in the basin. However, it is necessary to coordinate the development and utilization of water and soil resources, as this will guarantee not only an increased carbon sink but also the preservation of the carrying capacity of water and soil resources, ultimately achieving sustainable economic development in the Irtysh River Basin. The results of this study will help to promote the carbon cycle of the basin and the carbon sequestration capacity of the ecosystem, as well as provide a scientific basis for the establishment and management of the basin carbon pool.

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Response of plant community distribution in the pre-montane desert grassland on the southern slope of Tianshan Mountain to environmental factors: A case study in Baicheng County
LU Yuanbo, YAN Cheng, SONG Chunwu, LI Yajuan, LAI Zhaoyun
2023, 40 (8):  1346-1357.  doi: 10.13866/j.azr.2023.08.15
Abstract ( 42 )   HTML ( 5 )   PDF (4822KB) ( 49 )  

To investigate the response of plant community distribution to topography and soil factors in the pre-mountain desert grassland of Baicheng County on the southern piedmont of Tianshan Mountain, we selected a typical area for investigation. We used the dominance method and canonical correspondence analysis (CCA) to study the relationship between plant community distribution and topography and soil factors in the mountain desert grassland. We observed differences in the species diversity of shrub and herb layers between survey sample sites. Specifically, the Shannon-Wiener index, Pielou index, and Simpson index on the eastern slope showed more shrubs than herbs; while on the western and northern slopes, these indexes showed more herbs than shrubs. The results of CCA show that topographic factors influenced plant community diversity in the order of slope orientation > slope gradient > slope position; and soil factors influenced plant community diversity in the order of soil moisture in the 30-100 cm soil layer > total soil porosity (STP) > soil moisture in the 0-30 cm soil layer (SMC-1). Topography and soil factors had certain screening effects on the formation of plant communities. Soil moisture in the 30-100 cm soil layer and slope orientation were the key factors affecting the distribution of plant communities in the pre-mountain desert grassland of Baicheng County on the southern piedmont of Tianshan Mountain.

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Study on bacterial community structure and influencing factors in the northern margin of the Shanshan Kumtag Desert
LI Juan, LIU Yang, LIU Guangxiu, CHENG Liang, GUO Qingyun, ZHANG Wei, ZHANG Gaosen
2023, 40 (8):  1358-1368.  doi: 10.13866/j.azr.2023.08.16
Abstract ( 35 )   HTML ( 2 )   PDF (7853KB) ( 23 )  

The Shanshan Kumtag Desert, which is connected to the city, contains rich and unique microbial resources. To explore the microbial community structure and its relationship with environmental factors in the Shanshan Kumtag Desert, surface (0-5 cm) and deep (45-50 cm) layer sand samples were collected from four points along the northern margin of the desert. Subsequently, the collected samples were analyzed to determine the water content (WC), pH, total carbon (TC), total nitrogen (TN), total organic carbon (TOC), and electrical conductivity. High-throughput sequencing technology was used to analyze the bacterial community structure of the sand samples, and Spearman correlation was used to analyze the correlation between environmental factors and the bacterial community structure. The results showed that the collected sand samples were alkaline, and the dominant bacterial phyla were Actinobacteria, Firmicutes, Proteobacteria, and Bacteroidetes. Among these, the dominant genera were unclassified_f__Micrococcaceae, Bacillus, Sphingomonas, Escherichia-Shigella, and Microbacterium. Significant differences in the bacterial community structure were observed among the different points along the northern margin of the Shanshan Kumtag Desert (P < 0.05). However, no significant difference in species diversity was observed between the surface and deep layer samples. Furthermore, WC, TC, TN, and pH significantly affected the bacterial community structure in the surface samples (P < 0.05), while TOC significantly affected the bacterial community structure in the deep samples (P < 0.05). This study provides a theoretical basis for exploring microbial resources in the Shanshan Kumtag Desert and similar habitats.

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