Table of Content

15 May 2023, Volume 40 Issue 5 Previous Issue    Next Issue

Weather and Climate

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Study on the strong winter airborne dustfall mixed rain and snow events in Xinjiang, China in 2018 XUE Yibo, HUANG Shuangyan, ZHANG Xiaoxiao, LEI Jiaqiang, LI Shengyu 2023, 40 (5):  681-690.  doi: 10.13866/j.azr.2023.05.01 Abstract ( 239 )   HTML ( 28 )   PDF (11353KB) ( 148 )   An unusual winter synoptic process of mixed rain and snow with strong airborne dustfall occurred in Xinjiang, northwestern China from November 30 to December 3, 2018. Based on the meteorological records, environmental monitoring data, and continuous atmospheric dustfall observations, we analyzed the characteristics of the air pollutants during the synoptic process and studied their impact on the environment. The results showed that, during this anomalous synoptic process, >90% of the oasis cities in Xinjiang Province, China were affected by the atmospheric particulate pollution. The inhalable particulate matter comprised mostly coarse particles. This abnormal synoptic process caused the concentration of particulate matter to rapidly rise with PM10 (particulate matter with aerodynamic diameter ≤10 μm) concentration in Xinjiang reaching a maximum of 4745 μg·m-3. The occurrence of strong winds in the Xinjiang cities was highly positively correlated with the elevated PM10 concentration and air quality index. This synoptic process resulted in a total atmospheric dust deposition of approximately 0.9-1.52 million tons in the provincial capital city of Urumqi. The average airborne dustfall intensity in Urumqi was 85 g·m-2, exceeding the city’s annual average by 60%. This anomalous winter rain and snow mixed with eolian dust caused severe pollution of the atmosphere as well as intense atmospheric dustfall. Under the action of atmospheric circulation with jet streams, enormous amounts of particulates were transported to the oasis areas, seriously deteriorating the quality of the atmosphere in the urban environment. The Taklamakan Desert is the main pollution source for these strong winter dustfall events in Xinjiang, northwestern China. Figures and Tables | References | Related Articles | Metrics

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Comparison of the distribution and applicability of two typical atmospheric diffusion indices in Xinjiang ZHAO Keming, SUN Mingjing, LI Xia, SHI Junjie, AN Dawei, XU Tingting 2023, 40 (5):  691-702.  doi: 10.13866/j.azr.2023.05.02 Abstract ( 247 )   HTML ( 14 )   PDF (11303KB) ( 125 )   To quantitatively evaluate the effect of meteorological conditions on air pollution, data from 14 meteorological sounding stations and surface observation stations in Xinjiang were used to analyze the spatial and temporal distribution characteristics of atmospheric self-purification capacity index (ASI) and air stagnation index (ASITS) from 2010 to 2020. Results showed a negative correlation between ASI and ASITS. ASI was the largest in summer and the smallest in winter. It was generally greater in southern Xinjiang than in northern Xinjiang, whereas ASITS showed the opposite trend. This implied that the atmospheric diffusion conditions were better in southern Xinjiang than in northern Xinjiang, and a static and stable atmospheric circulation more easily formed in northern Xinjiang than in southern Xinjiang. The daily pollution data of air environment monitoring stations from 2015 to 2020 were used to determine the correlation between the air quality of Xinjiang in different seasons and the air quality of five heavily polluted stations and the two indexes. The two indexes highly correlated with the air pollution data of Urumqi station, and the static stability index was better, which can well indicate the degree of air pollution. However, no good correlation was found between the two indexes and the air pollution data of four stations in the southern Xinjiang basin. In the heavy pollution case in the spring of 2018, the PM10 concentration span was very large, so the two indexes showed a high dispersion on the scatter diagram, which is not applicable. In particular, in Hotan and Aksu, the two indexes showed a certain correlation with the pollutant concentration, and ASITS performed better. In Kashgar, ASI showed no correlation with air quality, and ASITS showed a weak correlation; the two indexes showed no correlation with the air quality of Korla, implying poor applicability. Further study on the distribution of indexes under different pollution levels in the capital city of Urumqi showed that the early warning indicators can be preliminarily condensed as follows: When pollutant emission is serious, and if ASI is distributed at 0-20 t·(d·km2)-1, it is susceptible to heavy weather pollution, and the range of ASITS is of little significance. Figures and Tables | References | Related Articles | Metrics

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The impact of the North Atlantic sea surface temperature anomaly on precipitation anomaly in Ningxia from late spring to early summer and associated mechanisms YANG Jianling,ZHANG Suzhao,MA Junbin,WANG Dai,Huang Yin 2023, 40 (5):  703-714.  doi: 10.13866/j.azr.2023.05.03 Abstract ( 264 )   HTML ( 22 )   PDF (18395KB) ( 78 )   This study was conducted to reveal the impact and mechanism of the North Atlantic sea surface temperature anomaly (SSTA) associated with Ningxia precipitation and to improve the accuracy of precipitation prediction ability in Ningxia. Based on the monthly precipitation data of 20 meteorological stations in Ningxia, NCEP/NCAR atmospheric data, Hadley center sea surface temperature data, and utilizing empirical orthogonal decomposition, composite, and correlation methods, we studied the relationships and their decadal changes between the North Atlantic SSTA and Ningxia precipitation anomaly from late spring to early summer (April-June). It was found that the relationship had continuously increased since 1961 but nonsignificantly until the 1980s. Since then, the North Atlantic Ocean “triple type” (NAT) SSTA in early winter and spring has caused precipitation anomalies in Ningxia from April to June but it differs each month. Corresponding to the positive (negative) phase NAT, Ningxia precipitation is more (less) in April, less(more) in May, and less northerly and more southerly (more northerly and less southerly) in June. Furthermore, the mechanism is revealed of NAT affecting Ningxia precipitation anomaly by inducing an atmosphere anomaly wave train in the area from Europe to the Asia-Pacific. The positivephase NAT can induce a wave train with atmosphere circulation anomaly pattern of geopotential height “west lower and east higher” at 500 hPa around Ningxia in April, which is the typical atmosphere anomaly pattern of more precipitation in Ningxia in April. Additionally, at the low layer of 850 hPa, the southerly wind anomalies transform warmer and humid air into Ningxia, contributing to more precipitation. In May and June, with the transition from spring to summer, the abnormal wave train polar shifts. In May, Ningxia is affected by the positive abnormal height field at 500 hPa in Baikal Lake area to East Asia, and the abnormal wind field in the low level of 850 hPa divergence, with less precipitation. In June, the positive height anomaly center at 500 hPa in East Asia continues to develop northward from south to north to Baikal Lake area, and splits from the positive anomaly height in the east of China into two anomaly centers. At 500 hPa, Ningxia north and south areas are affected by the atmospheric circulation pattern of geopotential height anomaly being “north higher and south lower” and “west lower and east higher”, respectively. Meanwhile, at low level 850 hPa weak northerly and southerly anomaly wind prevails in the north and south area of Ningxia respectively, being with divergence and convergence. All of these atmosphere anomalies are conducive to less precipitation in the north and more in the south of Ningxia. For negative NAT phase, all the atmospheric circulation and precipipation anomalies are vice versa. Figures and Tables | References | Related Articles | Metrics

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Analysis on variation characteristics of continuous air pollution in Lanzhou ZHAO Zhenzhu, MA Minjin, KANG Guoqiang, CAO Yidan 2023, 40 (5):  715-725.  doi: 10.13866/j.azr.2023.05.04 Abstract ( 227 )   HTML ( 18 )   PDF (4719KB) ( 153 )   This study was initiated to explore the pollution status of Lanzhou City in recent years and provide a reference for its prevention and management. The daily air quality index and mass concentrations of PM2.5, PM10, SO2, NO2, O3 (8 h, the 8 h moving average of ozone), and CO from 2014 to 2021 were used to analyze the monthly, seasonal, and interannual variation characteristics of air pollution in the valley city of Lanzhou. The changes in air pollutants and the continuous characteristics of air pollution in Lanzhou were also analyzed. The results show that the number of short-term mild continuous and long-term moderate and severe continuous pollution processes peaked in winter, the number of short-term moderate and severe continuous pollution processes peaked in spring, no moderate and severe continuous pollution processes occurred in summer, and long-term mild continuous pollution processes occurred more often in fall and winter. Pollutants that play a major role in the process of continuous pollution differ because of different seasons, durations, and grades of continuous pollution. The main pollutant in the mild, moderate, and short-term severe continuous pollution processes in winter is PM2.5, and the main pollutants in the long-term severe continuous pollution process are PM2.5 and PM10. The main pollutant in the continuous pollution process in spring is PM10, the main pollutant in the mild continuous pollution process in summer is O3 (8 h), the main pollutant in the short-term mild continuous pollution process in fall is PM10, whereas the main pollutants in the long-term mild continuous pollution process are PM10, PM2.5, and NO2. Figures and Tables | References | Related Articles | Metrics

Land and Water Resources

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Variation of runoff and sediment in the headwaters of the Yangtze River from 1980 to 2020 YAO Chunyan, LIU Honghu, LIU Jing 2023, 40 (5):  726-736.  doi: 10.13866/j.azr.2023.05.05 Abstract ( 234 )   HTML ( 14 )   PDF (21824KB) ( 106 )   The changes in soil loss, runoff, and sediment load in the headwaters of the Yangtze River and their correlation were studied based on the data of daily precipitation at 12 stations, and annual runoff and sediment at Zhimenda station in the headwaters of this river from 1980 to 2020. (1) The annual soil erosion modulus in the source area showed a significantly increasing trend (P<0.05), and the average annual soil erosion modulus was 4.71 t·hm-2·a-1. The erosion intensity and higher grades of erosion were mainly distributed in the southeast of the headwaters of the Yangtze River. (2) The runoff increased significantly (P<0.05), however, there was an abrupt change in 2004 when the suspended sediment concentrate and sediment load showed no significant change. (3) Precipitation had a significant positive effect on runoff and soil loss at 70% and 52.9%, respectively. Both runoff and soil loss showed direct positive effects on the sediment load. Precipitation, runoff, and soil loss explained 72.5% of the variation in sediment load. During this period, changes in precipitation had significant effects on soil loss and sediment in the headwaters of the Yangtze River. The results can provide a scientific basis for the research and evaluation of the effects of implementing ecological engineering in the headwaters of the Yangtze River. Figures and Tables | References | Related Articles | Metrics

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Effects of typical ecological projects of desertification combating on soil physical properties in Ulan Buh Desert GAO Junliang, LUO Fengmin, LIU Hongxin, QIAO Jingran, YU Meng, XU Yaxin 2023, 40 (5):  737-746.  doi: 10.13866/j.azr.2023.05.06 Abstract ( 140 )   HTML ( 9 )   PDF (13111KB) ( 69 )   To probe into the effects of typical ecological projects on improving soil moisture and other physical properties like water retention in Ulan Buh Desert, the desertification combating projects included straw checkerboard barrier and two native tree species (Haloxylon ammodendron and Hedysarum scoparium), and the shifting sandy land as the research object. The soil mechanical composition, moisture content, bulk density, porosity, water holding capacity, and water storage capacity of different soil layers at a depth of 0-100 cm were analyzed based on field sampling and lab analysis methods. The results showed that the ecological projects have a certain effect on the improvement of soil water physical properties and water retention of the aeolian sandy soil. (1) Compared to the control, the implementation of ecological projects promoted the apparent refinement of the grain size composition of the surface soil, showing decreased bulk density, increased soil porosity, and significantly increased soil water holding capacity and water storage capacity. (2) After the implementation of the typical ecological projects, the soil water retention was significantly improved, and the desertification land management effect was good. The results can provide basic data for the effective evaluation of regional desertification combating, and provide a scientific basis and theoretical reference for the type of selection of regional desertification combating ecological projects. Figures and Tables | References | Related Articles | Metrics

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Characteristics of soil nutrient accumulation after 38 years of the Jilantai Salt Lake protection system WEI Yajuan, LIU Meiying, XIE Yunhu, LI Xing 2023, 40 (5):  747-755.  doi: 10.13866/j.azr.2023.05.07 Abstract ( 156 )   HTML ( 6 )   PDF (7006KB) ( 47 )   This study was established to evaluate the influence of the Jilantai Salt Lake protection system on soil nutrient accumulation. This is a comparative study of soil nutrient accumulation in different protection system types under the salt lake protection system (zones for fixing shifting sand, fencing dunes for grass recovery, preventing wind and stopping sand, and a forest for protecting the salt lake) using the method of representative investigation and laboratory analysis. The goal was to provide a theoretical basis for the management of shelter forest in Jilantai Salt Lake. Our results showed the following: (1) The increases in soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), available nitrogen (AN), and available phosphorus (AP) contents were in the range of 0.45-1.92 g·kg-1, 0.03-0.58 g·kg-1, 0.15-0.43 g·kg-1, 1.33-13.31 mg·kg-1, and 0.12-12.94 mg·kg-1, respectively. Soil depth, protection system type, and their interaction had significant positive effects on the increase in the soil SOC, TN, TP, and AP contents. (2) Establishment of the salt lake protection system had a significant effect on soil nutrients at a depth of approximately 0-100 cm, and the soil depth, protection system type, and their interaction had a significant impact on soil TP relative interaction intense (RIITP), AN relative interaction intense (RIIAN), AP relative interaction intense (RIIAP), and total RII. (3) Nutrient restoration index showed that soil nutrients improved to different degrees in different protection system types of the salt lake protection system, and their nutrient restoration indexes of zones for fixing shifting sand, fencing dunes for grass recovery, preventing wind and stopping sand and a forest for protecting the salt lake were 7.83%, 37.72%, 185.12%, and 252.36%, respectively. This study showed that, in the 38 years since its establishment, the salt lake protection system could effectively promote soil nutrient accumulation and accelerate soil nutrient restoration in the salt lake area, benefitting the ecological restoration and reconstruction around Jilantai Salt Lake. Figures and Tables | References | Related Articles | Metrics

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Dynamic changes in soil moisture and its response to rainfall in Pinus sylvestris var. mongolica plantation in Horqin Sandy Land JIJI Jiamen, CHENG Yiben, CHEN Linglong, WAN Pengxiang, ZHANG Yihui, YANG Wenbin, BAI Xuying, WANG Tao 2023, 40 (5):  756-766.  doi: 10.13866/j.azr.2023.05.08 Abstract ( 233 )   HTML ( 17 )   PDF (6364KB) ( 134 )   After ecological restoration in Horqin Sandy Land, the soil moisture dynamics of the forest and its response to rainfall affect whether Pinus sylvestris var. mongolica(PSM) can be continuously used for the ecological restoration in the same type of area. To study the characteristics of soil moisture dynamics after vegetation restoration on the southern edge of Horqin Sandy Land, this study used the methods of in situ observation and numerical simulation and corrected the HYDRUS-1D model based on the measured data of soil moisture to explore its relationship with rainfall. We obtained the following results: (1) The regional moisture distribution was changed by the PSM plantation, deep soil recharge at 2.0 m in bare sand accounted for 44.16% of the annual rainfall, whereas deep soil recharge at 2.0 m in PSM land accounted for only 0.7% of the annual rainfall. (2) Soil moisture below a depth of 0.4 m had no response to light rain, but the response depth of soil moisture to moderate rain could reach 1.0 m. The response depth to heavy rain and rainstorm involved the entire observation profile. With increasing soil depth, a decreasing trend was observed in the variation in moisture fluctuation. (3) There was a strong correlation between rainfall and volumetric soil water content at shallow depth, and the cumulative rainfall at weekly and semi-monthly intervals was significantly correlated with the volumetric soil water content of each layer(P<0.05). Rainfall >50 mm can ensure the supply of soil moisture within 2.0 m. (4) The determination coefficient of the model was between 0.61 and 0.85, and the root mean square error ranged from 0.0061 to 0.0096 cm -3·cm -3. The accuracy of the deep layer simulation was higher than that of the shallow layer. These results have important implications for rain-fed vegetation afforestation in the Horqin Sandy Land. Figures and Tables | References | Related Articles | Metrics

Plant Ecology

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Effects of rare and endangered Ammopiptanthus mongolicus and associated species on soil characteristics in western Ordos WU Huimin, DANG Xiaohong, ZHAI Bo, WEI Yajuan, LI Xiaole 2023, 40 (5):  767-776.  doi: 10.13866/j.azr.2023.05.09 Abstract ( 169 )   HTML ( 8 )   PDF (6146KB) ( 116 )   This study was conducted to explore the influence of desert shrubs and their associated species on soil particle size and nutrient spatial heterogeneity under shrubs. The mixed community of Ammopiptanthus mongolicus and Sarcozygium xanthoxylon and a single plant of A. mongolicus in the Western Ordos National Nature Reserve were selected as the research samples. The surrounding bare sandy land without vegetation cover was used as control. The soil particle size characteristics, nutrient accumulation changes, and the relationship between nutrients and particle size composition under different shrub distribution types were analyzed. The results were as follows: (1) Compared with the mixed community of A. mongolicus-S. xanthoxylon, the volume percentages of soil clay, silt, and fine sand of the single A. mongolicus increased by 0.8%, 0.8%, and 0.71%, respectively. As the types of shrubs decrease, soil particle size became smaller in turn, sorting deteriorated, the fractal dimension became smaller, the soil particle distribution gradually became asymmetric, and the particle composition was concentrated at fine particles. (2) The contents of soil organic matter and alkali-hydrolyzable nitrogen increased by 1.85 g·kg-1 and 8.18 g·kg-1, respectively, with the increase in shrub species. The accumulation of organic matter and available phosphorus by a single A. mongolicus was stronger than that by A. mongolicus-S. xanthoxylon; however, the accumulation of alkali-hydrolyzable nitrogen was slightly poor than that of A. mongolicus-S. xanthoxylon. (3) A. mongolicus-S. xanthoxylon available soil phosphorus content was significantly positively correlated with fine sand content (P<0.05), and A. mongolicus available soil nitrogen and potassium were significantly positively correlated with coarse sand (P<0.05). A. mongolicus-S. xanthoxylon can effectively promote soil granulation and significantly improve soil nutrients. However, the presence of the associated species S. xanthoxylon reduced the enrichment of organic matter and available phosphorus by A. mongolicus. Figures and Tables | References | Related Articles | Metrics

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Asociation characteristics of Amygdalus pedunculata and the environmental factors driving them in Otindag Sandy Land CHEN Jiawei, CHU Jianmin, GAN Honghao, XU Lei, GONG Shuai, LIU Hao, WANG Yingxin, YANG Hongxiao, XU Xiaoqing, QI Danhui 2023, 40 (5):  777-784.  doi: 10.13866/j.azr.2023.05.10 Abstract ( 161 )   HTML ( 5 )   PDF (5655KB) ( 121 )   The stability of plant associations plays a vital role in the plant succession and safety of regional ecosystems. The biome of Amygdalus pedunculata is undergoing severe degradation because of climate change and human activities. Investigation of the characteristics of A. pedunculata associations and the factors affecting them can provide a scientific basis for restoring and managing the degradation of its biome. We conducted a study in Otindag Sandy Land to analyze the characteristics of the four typical A. pedunculata associations based on the surveyed data in 35 quadrats. Canonical correspondence analysis was used to detect the driving factors of the association distribution pattern in this region, and the relationship between species characteristics and environmental variables in each A. pedunculata association. Based on the differences in site conditions, the A. pedunculata community can be divided into four associations: Ⅰ, Amygdalus pedunculata-Allium mongolicum; Ⅱ, Amygdalus pedunculata-Stipa sareptana var. krylovii-Artemisia frigida; Ⅲ, Amygdalus pedunculata-Eragrostis pilosa; and Ⅳ, Ulmus pumila-Amygdalus pedunculata-Corispermum mongolicum. In general, temperature and elevation were the main environmental factors regulating the distribution of A. pedunculata associations with contribution rates of 13.2% and 11.4%, respectively. Soil organic matter (10-20 cm and 20-30 cm) was the determinant affecting the structure of the A. pedunculata associations. Associations I and II are influenced by elevation, growing season temperature, and 0-10 cm soil organic matter; association III is more sensitive to climatic and soil factors; and association IV is regulated by elevation. Figures and Tables | References | Related Articles | Metrics

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Numerical simulation of the influence of typical shrub types on wind-sand flow field YAN Qing, LI Juyan, YIN Zhongdong, LIU Jinmiao, LIU Hongcai 2023, 40 (5):  785-797.  doi: 10.13866/j.azr.2023.05.11 Abstract ( 185 )   HTML ( 6 )   PDF (10014KB) ( 59 )   The purpose of this study was to provide a theoretical basis for the rational selection of different vegetation types for wind and sand control in arid and semiarid areas. Fluent software was used to numerically simulate the flow field around three types of typical strains (altar-shaped, shuttle-shaped, and broom-shaped) of scrub to analyze the influence of different plant forms on wind and sand flow and verify the results using existing wind tunnel tests. Results showed that (1) The flow field around the three types of plants can be divided into five zones, and three eddies exist behind the plants. Due to the intensity of the eddies, during the initial phase of sand accumulation, shuttle-shaped and broom-shaped plants accumulated sand primarily at 6-7 H after the plant, whereas altar-shaped plants accumulated sand at 3 H. (2) Affected by the height layer of the maximum profile area of the plant, the minimum wind speed at 1 H after the three types of plant shrubs appeared at heights of 0.3, 0.4 m, and 0.8 m, and the optimal protection range of height was 0.2-0.4 m, 0.3-0.6 m, and 0.8-1 m, respectively. The aerodynamic roughness of the three plant types decreased gradually, and the roughness of the altar-shaped plants was significantly higher than that of the other two plant types. (3) All three types of strains could effectively reduce wind speed in the range of -2-10 H. The wind protection benefits in the near-surface area after the strains are altar-shaped > shuttle-shaped > broom-shaped the wind protection benefits in the mid-altitude area all decrease with increasing plant distance. (4) At T = 10 s, the total duration of sand accumulation around the three plants was 8.5 H, 6 H, and 4.5 H, respectively, and wind erosion existed to different degrees at 5-5.5 m and 4.5-6 m from the entrance for Haloxylon ammodendron and Calligonum mongolicum, respectively. Compared with other plants, Nitraria tangutorum exerted a better sand-blocking effect. Hence, it is recommended to combine N. tangutorum with H. ammodendron and C. mongolicum in the construction of wind and sand fixation projects, so that the sand-blocking property of N. tangutorum can be effectuated, and the better wind-blocking effect of H. ammodendron and C. mongolicum can be utilized at medium and high altitudes. Figures and Tables | References | Related Articles | Metrics

Ecology and Environment

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Analysis of the spatiotemporal conversion between ecological land and production land in the farming-pastoral ecotone and the forces driving it: A case study in the Bashang region of Zhangjiakou QIN Yanjie, WU Aibin, ZHAO Yanxia, TANG Shoupu, LIU Xin, SHEN Huitao, ZHANG Shenghai 2023, 40 (5):  798-807.  doi: 10.13866/j.azr.2023.05.12 Abstract ( 210 )   HTML ( 12 )   PDF (3941KB) ( 102 )   In farming-pastoral ecotone, coordinated development between ecological land and production land is of great significance. A land use transfer matrix was constructed in the Bashang region. We used the geographic concentration method and the geographic detector model to detect the spatiotemporal change, transformation characteristics, and its driving force between ecological land and production land. The results showed the following: (1) From 2000 to 2020, the ecological land area increased by 5.41%, although the trend appearedto decrease; meanwhile, the production land area decreased by 6.89%, although the trend appeared to increase. (2) The conversion between ecological land and production land occurred frequently. The area converted from production land to ecological land was 21.23×104 hm2, and the conversion amount decreased. These conversions were mainly distributed in regions with rich natural conditions (abundant rainfall, low altitude, and gentle slope). The area converted from ecological land to production land was 12.47×104 hm2, and the conversion amount increased. These conversions were mainly distributed in regions with poor natural conditions (low rainfall, high altitude, and steep slope). (3) In the single factors, soil organic matter, per capita cultivated land area, and slope arewere the main factors influencing the conversion from production land to ecological land. In the interaction factors, the interaction between soil organic matter and per capita cultivated land area was the most influential factor. The conversion from production land to ecological land usually occurred in the regions with low soil organic matter content, large per capita cultivated area, slope of 6°-15°, and annual average rainfall of <400 mm. Slope, annual average rainfall, and per capita cultivated land area were the main factors influencing the conversion from ecological land to production land. The interaction between slope and geomorphic agents was the most influential factor. The conversion from ecological land to production land usually occurred in the regions with a slope of 2°-6°, annual average rainfall of >400 mm, and small per capita cultivated land area. Attention should be drawn to the conversion between ecological land and productive land in the study area over the coming years. Figures and Tables | References | Related Articles | Metrics

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Spatial and temporal patterns of ecological resilience under alternative stable states in the desert of the north Fukang region Xu Yuzhe, Lin Tao, Li Jun 2023, 40 (5):  808-817.  doi: 10.13866/j.azr.2023.05.13 Abstract ( 202 )   HTML ( 5 )   PDF (13705KB) ( 84 )   The ecological resilience of desert ecosystems under alternative stable states reflects the ecosystem’s ability to recover from environmental disturbances, which has important theoretical implications for understanding the desert ecosystem processes. Recent research has focused on some intensively studied ecosystems such as lakes and forests, whereas studies related to the ecological resilience of desert ecosystems have hardly considered alternative stable states as well as the temporal changes in resilience. In this study, based on the MODIS global vegetation index from January 2001 to December 2020, we used Breaks for Additive Season and Trend and state-space modeling to determine the temporal-spatial pattern of ecological resilience under alternative stable states quantified by the exit times for a transect extending from the southern edge to the hinterland of Gurbantunggut Desert in north Fukang. Moreover, mechanisms underlying the temporal-spatial pattern of ecological resilience were explored. The results of this study indicated the following: (1) Resilience+ and Resilience- showed a decreasing trend within the study period but with significant differences between the southern edge and the hinterland of the desert. (2) Ecological resilience also showed a lagged response to precipitation changes. (3) Differences in the seasonal patterns of precipitation could weaken the correlation between precipitation and ecological resilience. In summary, the spatial distribution of ecological resilience is generally controlled by the precipitation patterns, but the spatial heterogeneity of vegetation due to site conditions increases the complexity of the spatial distribution of ecological resilience, with the relationship between ecological resilience and precipitation resulting from the combined effects of the composition of vegetation, adaptation of plants to changes in precipitation, and the seasonal pattern of precipitation. Our study is important for understanding the mechanisms that desert ecosystems utilize to maintain functional stability as well as in desert conservation and ecological restoration. Figures and Tables | References | Related Articles | Metrics

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Temporal and Spatial changes and the driving factors of vegetation NPP in Shiyang River Basin REN Liwen, WANG Xingtao, LIU Mingchun, WANG Dawei 2023, 40 (5):  818-828.  doi: 10.13866/j.azr.2023.05.14 Abstract ( 193 )   HTML ( 17 )   PDF (12250KB) ( 105 )   We estimated the vegetation NPP using the CASA model (Carnegie-Ames-Stanford Approach) in the Shiyang River Basin from 2000 to 2020 and analyzed the temporal and spatial variations, stability, and the future change trends of NPP. The influencing factors were also studied from three aspects, namely climate factors, topographic factors, and human activities. The results showed the following: (1) The average vegetation NPP in Shiyang River from 2000 to 2020 was 291.01 g C·m-2·a-1 and the increase was insignificant. The spatial distribution of vegetation NPP was generally high in the south and low in the north. (2) The proportion of the area of vegetation NPP increased by 86.4% since 2000. The proportions which were extremely significant increased significantly increased were 6.7% and 10.1%, respectively. (3) The proportion of the area where the change in vegetation NPP was moderately above a fluctuation degree [coefficient of variation (Cv)≥0.25] was 50.4%. (4) The future change trend indicated that the ability for vegetation NPP to continuously improve was weak, and the proportion of the area where the vegetation NPP had increased but could be reversed in the future was 57.1%. (5) The vegetation NPP was positively correlated with temperature and precipitation, but it was more sensitive to temperature. With increasing elevation and slope, the vegetation NPP first increased and then decreased. Artificial afforestation and returning farmland to forest and grassland significantly improved the vegetation NPP in recent years. Figures and Tables | References | Related Articles | Metrics

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Construction of ecological security patterns in the Kaidu-Kongque River Basin based on the supply and demand of ecosystem services YAN Yujiang, LI Jiangui, LI Junli, Jiang Teng 2023, 40 (5):  829-839.  doi: 10.13866/j.azr.2023.05.15 Abstract ( 195 )   HTML ( 9 )   PDF (8765KB) ( 98 )   The construction of an ecological security pattern in arid zones is conducive to promoting a dynamic balance between the supply and demand of regional ecosystem services. This study involves the Kaidu-Kongque River Basin in an arid zone and uses the InVEST model, the RWEQ model, and the Getis-Ord Gi* model to analyze the ecological supply sources, degree of land use, GDP per km2, population density, and the nighttime light index. This approach was used to analyze the ecological demand sources and determine the ecological corridors between supply and demand sources based on the minimum cumulative resistance model so as to construct an ecological security pattern of the study area. The results of the study are as follows: (1) There are 14 ecological supply source areas in the Kaidu-Kongque River Basin, accounting for 21.46% of the study area, and a total of 9 patches of key ecological demand source areas, accounting for 4.63% of the total area of the basin; 126 ecological corridors, including a total of 17 important corridors with a total length of 654.68 km; 65 ecological nodes, including 24 key ecological nodes. (2) The spatial mismatch between supply and demand of ecosystem services in Kaidu-Kongque River Basin is obvious, and the high supply area and high demand area show obvious characteristics with urban boundary as the dividing line. (3) Combining the natural geographic characteristics and the mobility of landscape ecosystem services in the study area, the resistance surface model is used to construct “two cores, two zones, three horizons, four verticals, and multiple nodes” of the Kaidu-Kongque River Basin. In conclusion, the ecological security pattern of the Kaidu-Kongque River Basin can provide a scientific reference for protecting regional ecosystem service functions and formulating sustainable development policies. Figures and Tables | References | Related Articles | Metrics

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Survey of species diversity of darkling beetles in the Minqin temperate desert steppe TA Fuyuan, ZHANG Hongyang, GOU Wenshan, MA Weixin, HU Guixin 2023, 40 (5):  840-848.  doi: 10.13866/j.azr.2023.05.16 Abstract ( 192 )   HTML ( 7 )   PDF (3540KB) ( 127 )   To clarify the diversity and temporal dynamics of darkling beetles in Minqin temperate desert grassland, this study systematically investigated the communities of different subtypes of darkling beetles in gravelly, sandy, and saline desert grasslands in Minqin County, Gansu Province, from April to October 2021 using the pitfall trapping method. In this survey, 8492 individuals of 10 species in 8 genera were captured. The dominant species in the desert steppe in general were Microdera elegans and Sternoplax setosa setosa, which accounted for 26.57% and 25.07%, respectively, of the total individuals, whereas Eumylada potanini was an endemic species in gravelly desert grassland. The number of darkling beetles of their respective species in the three subtypes of desert grasslands peaked in July and dropped to the lowest level in October. The community abundance and Shannon-Wiener diversity index of the darkling beetles were significantly higher than those in saline desert grassland (P<0.05), and the community richness of darkling beetles was significantly higher than that of sandy desert grassland (P<0.05). The diversity of the darkling beetles was closely correlated with environmental factors: The community abundance index was significantly negatively correlated with the height of the vegetation community, soil water content, and vegetation cover (P<0.05). The abundance index of the darkling beetles was significantly positively correlated with the plant Shannon-Wiener diversity index and plant richness (P<0.05). The vegetation composition of the desert grassland is simple; therefore, the community composition of the darkling beetles is also simple. The plant diversity index and plant richness are higher in gravelly desert grasslands than in saline desert grasslands and sandy desert grasslands, so the darkling beetles are the most abundant in gravelly desert grasslands. Figures and Tables | References | Related Articles | Metrics