Table of Content

15 April 2023, Volume 40 Issue 4 Previous Issue    Next Issue

Weather and Climate

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Analysis of spatial and seasonal variations in climate warming and humidification in Northwest China ZHANG Hongli, HAN Fuqiang, ZHANG Liang, WANG Lixia, SUN Yuan, LI Fumin 2023, 40 (4):  517-531.  doi: 10.13866/j.azr.2023.04.01 Abstract ( 391 )   HTML ( 63 )   PDF (21971KB) ( 223 )   Further exploration of trends in climate warming and humidification in Northwest China can deepen our understanding of important scientific issues regarding the responses to global warming of arid and semi-arid regions of the Northern Hemisphere in mid-and high latitudes. Using statistical methods such as linear trend, Kriging interpolation, and non-parametric Mann-Kendall test for temperature and precipitation data from 127 stations in Northwest China from 1961 to 2021, we show the following: (1) In the last 60 years, Northwest China as a whole has undergone significant warming and humidification. The regional warming trend was relatively consistent [0.32 ℃·(10a)-1], while there was a clear regional imbalance of humidification, with the humidification in the west of Northwest China increasing earlier, more steadily, and more significantly than in the east. (Increases in the west were mainly distributed in Northwest Xinjiang, while those in the east were mainly in the Qinghai region). (2) There were pronounced interdecadal fluctuations of warming and humidification, and paradigm shifts in temperature and precipitation trends of Northwest China occurred in 1993 and 2010, respectively, after which the rates of warming and humidification were 0.08 ℃·(10a)-1 and 37.60 mm·(10a)-1 higher than beforehand. Warming and humidification were more prominent after these paradigm shifts, with the eastward expansion of warming and humidification being the main feature. (3) The seasonal imbalance of warming and humidification also showed that the warming was most significant in winter in western Northwest China, followed by that in summer; winter precipitation increased significantly in western Northwest China, while spring and summer precipitation increased significantly in eastern Northwest China. These results can provide a theoretical basis for formulating climate change countermeasures in Northwest China. Figures and Tables | References | Related Articles | Metrics

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The influence and prediction of SST predictors at different timescales on summer precipitation over the eastern part of Northwest China ZHANG Wen, MA Yang, WANG Dai, YANG Jianling, CUI Yang 2023, 40 (4):  532-542.  doi: 10.13866/j.azr.2023.04.02 Abstract ( 234 )   HTML ( 21 )   PDF (9387KB) ( 111 )   The dominant sea surface temperature anomaly (SSTa) modes of decadal and interannual variations in summer precipitation over the eastern part of Northwest China (ENC) were here analyzed by power spectrum and composite analyses. The summer precipitation averaged at 155 stations over the ENC, the monthly SSTa, and circulation reanalysis data from 1961 to 2020 were used. The SSTa predictors before and after the timescale decomposition were obtained to establish precipitation prediction models by using linear regression. The results showed that the summer precipitation over the ENC has not only an decadal period of about 30 years but also a 3-year interannual cycle. The Pacific Decadal Oscillation (IPO) has played a leading role in decadal variations in summer precipitation. The positive phase of IPO in the precedent spring is conducive to more precipitation; meanwhile, it is in the background of less precipitation. The tropical Indian Ocean, the tropical western Pacific, and the North Atlantic provide interannual SSTa signals. The negative (positive) phase of tropical Indian Ocean SSTa, the positive (negative) phase of the Atlantic tripole SSTa, and the cold (warm) SSTa in the tropical western Pacific Ocean in the precedent spring, corresponding to the high (low) pressure anomalies over Lake Balkhash in mid- to high latitudes, with northward (southward) and weak (strong) characteristics in the subtropical High over the Western Pacific, favor less (more) summer precipitation over the ENC. Moreover, taking the decadal and interannual variations of SSTa into account can potentially contribute to improving forecasting of summer precipitation over the ENC, with the annual average Ps and Pc scores during the independent test samples based on the scale decomposition model being 6% and 7% higher than those in the original model, respectively. Figures and Tables | References | Related Articles | Metrics

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Comprehensive evaluation of atmospheric environmental parameters of short-duration rainstorm in Hedong region of Gansu Province based on fuzzy mathematics ZHAO Yujuan, LU Yaqi, ZHANG Hongfen, ZHANG Kexin, ZHOU Zhongwen, Liu Ying 2023, 40 (4):  543-551.  doi: 10.13866/j.azr.2023.04.03 Abstract ( 201 )   HTML ( 8 )   PDF (4242KB) ( 103 )   It is necessary to comprehensively evaluate the influence of various atmospheric environmental parameters on short-duration rainstorm forecasts in the Hedong region of Gansu Province in order to improve the short-duration rainstorm forecast equation and accuracy. Based on precipitation data from the flood season of 2013 to 2018 in the Hedong region of Gansu Province, using the percentile method, the threshold of short-duration rainstorms from June to August in Hedong was calculated. Ninety-two cases of short-duration rainstorms in the Hedong region of Gansu Province were selected based on the threshold of time-to-storm rain. Using ECMWF 0.25°×0.25° reanalysis data to analyze the atmospheric environmental parameters, it was found that the K index, relative humidity of 700 hPa, the atmospheric precipitable amount, and other parameters are good indicators of short-duration rainstorms in the Hedong region of Gansu Province. Based on the method of fuzzy mathematics, considering the significance and moderation, a comprehensive evaluation plan for 28 atmospheric environmental parameters was constructed, and the weights of atmospheric environmental parameters in different periods were obtained. The analysis shows that, when short-duration rainstorms occur in the flood season in the Hedong region of Gansu Province, the weights of atmospheric environmental parameters differ in different periods. When forecasting a short-duration rainstorm, the weight of atmospheric environmental parameters in the period in which it is located should be considered, and the parameters with the highest weight ranking should mainly be considered. Figures and Tables | References | Related Articles | Metrics

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Spatiotemporal variation characteristics of precipitation pH in Inner Mongolia from 1991 to 2021 HU Yanan, PEI Hao, JIANG Yanfeng, MIAO Bailing, JIA Chengzhen 2023, 40 (4):  552-562.  doi: 10.13866/j.azr.2023.04.04 Abstract ( 473 )   HTML ( 19 )   PDF (8186KB) ( 125 )   This study was established to understand the evolution of precipitation pH in Inner Mongolia since the 1990s, using the observation data of acid rain stations in Inner Mongolia, as well as meteorological elements and atmospheric pollutant concentration data, along with statistical analysis of the spatial and temporal distribution characteristics and factors influencing precipitation pH, and the frequencies of acid rain and alkali rain. The threshold of alkali rain refers to acid rain, which is defined as precipitation with pH >8.4. The conclusions are as follows: (1) Owing to the soil pH in Inner Mongolia mostly being alkaline and there being a strong buffering effect of wind sand, the proportion of alkaline precipitation is higher than that of acidic precipitation in most of Inner Mongolia, while the proportion of acidic precipitation is higher in Manzhouli in the northeast. The occurrence of acid rain and alkali rain accounted for 1.1% and 3.6%, respectively, having a low probability of occurrence. (2) The spatial distribution of the pH of precipitation shows the following order: central > western > eastern. The average annual precipitation pH range of the Inner Mongolia acid rain stations in the studied 15 years was 6.2 (Manzhouli) to 7.2 (Xilinhot), reflecting that this is not a highly acid rain-affected region. In the last 5 years, the frequency of acid rain and alkali rain has decreased in most areas, but the frequency of acid rain in Urad Middle Banner and alkali rain in Alxa Left Banner has increased significantly. (3) Low pH of precipitation mostly occurs from June to September in the summer flood season, and high pH mostly occurs from April to May in spring and January to February in winter, being closely related to vegetation coverage, precipitation, wind speed and direction, dust, and cold waves, among other factors. In addition, owing to the release of acidic gases such as SO2 and NOx from coal burning for heating during cold periods, the pH of precipitation is also low in winter and spring in Hohhot, Tongliao, and other regions with relatively high concentrations of air pollutants. Figures and Tables | References | Related Articles | Metrics

Land and Water Resources

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Spatial differentiation mechanism of land cover and related changes in water-carbon variables in Wuding River Basin LYU Jinxin, LIANG Kang, LIU Changming, ZHANG Yihui, LIU Lu 2023, 40 (4):  563-572.  doi: 10.13866/j.azr.2023.04.05 Abstract ( 254 )   HTML ( 8 )   PDF (10175KB) ( 76 )   The Wuding River Basin is the key area for the implementation of the grain for green program on the Loess Plateau. Exploring the spatial differentiation mechanism of land cover and the characteristics of variation of related water-carbon variables is essential for supporting water and soil resources conservation and planning, along with serving the construction of regional ecological civilization. Here we used the linear tendency method, Mann-Kendall trend test, Pettitt test, and geodetector to analyze the spatiotemporal characteristics and the factors driving the spatial differentiation of land cover in Wudinghe River Basin. In addition, from the perspective of land-water-carbon coupling, we analyzed the characteristics of variation of total primary productivity (GPP), actual evapotranspiration (ET), and water use efficiency (WUE). Three main results were as follows: (i) The total grassland, forest, and construction land increased significantly, while the cropland and barren land decreased significantly during 1990-2019. The area of forest and grassland increased mainly in the lower reaches of the basin and along Wuding River. (ii) Population density, precipitation, and temperature have a significant impact on the spatial pattern of land cover. On the whole, the influence of socioeconomic factors is greater than that of natural factors, but the influence of natural factors represented by precipitation and temperature is increasing. (iii) There is a good correlation between the variation of water-carbon variables and land cover change. Spatially, GPP, ET, and WUE are relatively high in the southeastern part of the basin where cropland, forest, and grassland are the main cover, while they are lower in the northwestern part of the basin where grassland and barren land are the main cover. In terms of time, GPP, ET, and WUE all showed increasing trends during 2001-2019. GPP and WUE increased significantly in most parts of the basin, while ET increased significantly mainly in its middle and lower reaches. In conclusion, under the implementation of the grain for green program and climate change, the forest and grass in Wudinghe River Basin have been restored and the ecology has been improved. Figures and Tables | References | Related Articles | Metrics

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Coupling relationship and spatiotemporal differentiation of the water-energy-food-ecology nexus in five Central Asian countries WU Yueting, GUO Lidan, JING Peiran, HUANG Feng, WANG Haoxuan 2023, 40 (4):  573-582.  doi: 10.13866/j.azr.2023.04.06 Abstract ( 325 )   HTML ( 15 )   PDF (4079KB) ( 198 )   To shed light on the complex transboundary water problems in Central Asia, a study on water-energy-food-ecology (WEFE) system coordination was conducted from the regional and national levels based on a system coupling perspective. First, the WEFE evaluation index system for coupling and coordination was constructed, and then the coupling coordination degree model was applied to quantitatively evaluate the level of coordinated development of WEFE and its spatial and temporal evolution in Central Asia. The results show that: (1) In the last 20 years, the coupling degree of WEFE in Central Asia basically maintained a high level, and the coupling coordination degree showed a slow growth trend but was barely coordination. (2) The development level of coupling coordination varied greatly among countries, and the coupling coordination level of Kazakhstan was the best, albeit in primary coordination. Tajikistan and Kyrgyzstan barely performed coordination, and Turkmenistan and Uzbekistan were on the brink of misalignment. (3) Comparing the development levels of multiple systems, it was found that there was a significant lag in the food system in Tajikistan and Kyrgyzstan, a lag in the water system in Turkmenistan, and a lag in the energy system in Kazakhstan and Uzbekistan, which failed to achieve a good match among systems and affected the regional coordinated development to a certain extent. The results can provide a basis for decision-making on the synergistic development of WEFE in Central Asia and transboundary river development cooperation among countries. Figures and Tables | References | Related Articles | Metrics

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Downscaling analysis of SMAP soil moisture products in Gurbantunggut Desert XUE Zhixuan, ZHANG Li, WANG Xinjun, LI Yongkang, ZHANG Guanhong, LI Peiyao 2023, 40 (4):  583-593.  doi: 10.13866/j.azr.2023.04.07 Abstract ( 281 )   HTML ( 14 )   PDF (5303KB) ( 309 )   The low spatial resolution of SMAP products limits its applicability to sparsely vegetated arid regions and deserts with high surface heterogeneity. Considering the special environmental characteristics of sparsely vegetated desert areas in arid regions, traditional downscaling methods such as land surface temperature (LST), normalized difference vegetation index (NDVI), and digital elevation model (DEM) have been used, among others. Based on the scale factor, the enhanced modified soil-adjusted vegetation index (Enhanced Modified Soil-Adjusted Vegetation Index, EMSAVI) and the ratio sand brightness index (RSBI), which are more correlated with the desert surface soil moisture, were added to reflect the study area. For the downscaling factors of vegetation coverage and bare sand distribution, the random forest (RF) algorithm was used to build a soil moisture downscaling model in arid areas. The results showed the following: (1) Correlation analysis showed that EMSAVI (rdry = -0.37, rwet = -0.34) and RSBI (rdry = -0.42, rwet = -0.25) were good indicators of desert soil moisture, being superior to NDVI (rdry = -0.21, rwet = 0.08). (2) The importance of EMSAVI and NDVI was 18.7% and 13.2%, respectively, and EMSAVI contributed more to the construction of the downscaling model. (3) The results obtained from the soil moisture downscaling model in dry and wet season arid regions and R2 of the SMAP product reached 0.916 and 0.910, and the RMSE reached 0.0075 cm3·cm-3 and 0.0063 cm3·cm-3, respectively, which are lower than the RMSE of the traditional model of 0.0013 cm3·cm-3. (4) By calculating the difference (LBPC) of LBP (local binary patterns) to evaluate the spatial consistency, the result of the newly constructed downscaling model (0.0585) was better than that of traditional downscaling (0.0645). This research shows that introduction of the short-wave infrared band into the EMSAVI established by the vegetation index enables its better application to the study of soil moisture downscaling in sparsely vegetated desert areas in arid regions. Figures and Tables | References | Related Articles | Metrics

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Rainfall response of soil water content on a slope of Larix principis-rupprechtii plantation in the semi-arid Liupan Mountains SHI Jianzhou, LIU Xiande, TIAN Qing, YU Pengtao, WANG Yanhui 2023, 40 (4):  594-604.  doi: 10.13866/j.azr.2023.04.08 Abstract ( 253 )   HTML ( 17 )   PDF (6697KB) ( 92 )   In the semi-arid zone of the Liupan Mountains in Ningxia, soil water content is a key factor affecting the survival and growth of trees, and it is necessary to understand the differences in soil water content on different slope positions of forested slopes and their response to different rainfall amounts. For this purpose, a typical slope covered by Larix principis-rupprechtii plantations was selected in the small watershed of Diediegou in the Liupanshan Mountains. From May to October 2021, meteorological conditions (such as precipitation) and changes in soil water content on this slope were continuously monitored with automatic weather stations and soil moisture meters to analyze the differences in soil water content on the slopes and their response to the depth of individual rainfall events. The total precipitation depth during the monitoring period was 443.7 mm, which was close to the long-term annual average, but with severe drought in summer. The results showed the following: (1) The soil water content varied significantly within the growing season; the overall level first decreased and then increased, being the lowest in August (0.112 m3·m-3). (2) There were clear differences in soil water content among slope positions, generally in the order upper slope [(0.191 ± 0.044) m3·m-3] > middle slope [(0.158 ± 0.045) m3·m-3] > lower slope [(0.146 ± 0.034) m3·m-3]. This indicated that the main factor influencing the differences in soil water content along slope positions is the amount of evapotranspiration by forest/vegetation, rather than the redistribution of rainwater along the slope by slope runoff in this dry year. (3) To the same rainfall depth, the response of soil water content on the middle slope was the most sensitive, followed by that on the upper slope, and the lower slope was the least sensitive, owing to the integrated effects of soil porosity, water-holding capacity, and understory vegetation. (4) At the study site, rainfall was dominated by small rainfall events below 10 mm, with 7 mm representing the threshold for effective rainfall, above which the rainfall is likely to alleviate the soil dryness and recharge the soil moisture in the soil layer of 0-20 cm. The results of this study can aid understanding of the variation and spatial distribution of soil water content on forest slopes in semi-arid mountainous areas and help determine the water-carrying capacity of forest/vegetation and integrated Figures and Tables | References | Related Articles | Metrics

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Analysis of impact of human activities on runoff changes in Yue River Basin of the Qinling Mountains DUAN Yujia, HE Yi, ZHAO Jie, WU Qiong 2023, 40 (4):  605-614.  doi: 10.13866/j.azr.2023.04.09 Abstract ( 222 )   HTML ( 20 )   PDF (5821KB) ( 145 )   Climate change and human activities are the main driving forces of river runoff variation. Under the similar weather condition (SWC), human activities are the dominant factors for change of discharge in the basin that quantitative identification on the action mechanism of human activities on runoff change has great significance to further explore the change characteristics of runoff. This study was conducted in the Yue River basin of the Qinling Mountains. Combined with Land-Use and Land-Cover Change (LUCC) as well as Normalized Difference Vegetation Index (NDVI), human activities’ impacts on runoff is quantified by analyzing runoff changes in the Yue River basin with similar weather condition. The results show that: the average runoff value from 1960 to 2018 is 8.3×108 m3. The discharge shows a decreasing trend as a whole, and the change trend is not significant. Under the similar weather condition, this research obtains 6 paired-years. Among them, the annual runoff of 3 paired-years increased and that of 2 paired-years decreased. Taking the third paired-year (2000 and 2016) as an example to quantitatively distinguish the impact of climate change and human activities on runoff which reduced by 4.7×108 m3 in 2016 compared with 2000. In the third paired-year (2000 and 2016), 25751.4 hm2 of arable land was converted into forest land, and the forest land area increased by 24998.9 hm2. The NDVI change is mainly caused by human activities. The area increased by NDVI in 2016 was 242652.0 hm2 compared with that in 2000. The change trend of NDVI is opposite to that of runoff. This study can provide a theoretical basis for quantitative evaluation for human activities’ impact on river runoff changes within the Qinling Mountains. Figures and Tables | References | Related Articles | Metrics

Plant Ecology

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Distribution characteristics of carbon density in the arbor and soil layers of Qinghai spruce forest on the southern slope of Qilian Mountains with altitude QIU Xunxun, CAO Guangchao, ZHANG Jinhu, ZHANG Zhuo, LIU Menglin 2023, 40 (4):  615-622.  doi: 10.13866/j.azr.2023.04.10 Abstract ( 259 )   HTML ( 18 )   PDF (2648KB) ( 194 )   Forest biomass is the basis for studying forest primary productivity, and its carbon density is a crucial indicator for evaluating the structure and function of forest ecosystem. To study changes in the stand density of Qinghai spruce with altitude in Amidongsoe small watershed on the southern slope of Qilian Mountains, a biomass model was used to calculate the carbon density of arbor and soil layers along an altitude gradient of 2900-3200 m at different altitudes. The aim of this study was to gather basic data for estimating carbon storage in spruce forests in the Qilian Mountains and Qinghai Province. The results demonstrated that the average value of total biomass in the study area was 135.59 t·hm-2 and the total biomass decreased as the altitude increased. The average carbon density of tree layer was 70.51 t·hm-2, and the average organic carbon density of the 0-50 cm soil layer was 154.01 t·hm-2. As the altitude increased, the carbon density of the tree layer exhibited a decreasing trend, and the soil organic carbon density of the tree layer initially decreased and then increased. At different elevations, the carbon density of spruce forest ecosystem was 224.51 t·hm-2, with the carbon density of the tree and soil layers accounting for 30.5% and 69.5% of the total carbon density, respectively. The layers showed a decreasing trend as the altitude increased. Protecting forest soil is crucial for maintaining ecological balance, as the forest soil carbon pool represents a considerable proportion of the total carbon density. Figures and Tables | References | Related Articles | Metrics

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Spatiotemporal change and analysis of factors driving forest-grass vegetation coverage in Hetao Irrigation District based on geographical detector LI Xinlei, LI Ruiping, WANG Xiuqing, WANG Sinan, WANG Chengkun 2023, 40 (4):  623-635.  doi: 10.13866/j.azr.2023.04.11 Abstract ( 256 )   HTML ( 18 )   PDF (13324KB) ( 80 )   Based on the data on forest and grass vegetation coverage from 2000 to 2019, the spatiotemporal change of forest and grass vegetation in Hetao Irrigation District over 20 years was analyzed, and the influence of various factors driving forest and grass vegetation coverage was quantitatively analyzed using a geographical detector. The results showed the following: (1) The area of forest and grassland in Hetao Irrigation District showed a decreasing trend in the studied 20 years, with a decrease of 966.15 km2. The vegetation coverage level of forest and grassland showed an overall upward trend. The average annual vegetation coverage of forest and grassland was 28.3%. On the spatial scale, the vegetation coverage of forest and grassland in Hetao Irrigation District showed a spatial variation characteristic of decreasing from northeast to southwest. (2) In the studied 20 years, the centers of gravity of low forest and grass vegetation coverage and medium forest and grass vegetation coverage have mainly been located in the northeast of Yongji irrigation area and the southwest of Yichang irrigation area, respectively. The centers of gravity of forest and grass vegetation coverage at all levels show a decreasing trend from northeast to southwest, and all show a trend of migration to the southwest. The migration distance in each period was between 0.71 and 15.46 km. (3) Distance from water, groundwater depth, temperature, and precipitation are the dominant environmental factors affecting the forest and grass vegetation coverage in the region, with explanatory power of 0.427, 0.439, 0.318, and 0.368, respectively. The interaction between distance from water, groundwater depth, annual average precipitation, and other factors is generally higher, and the regional water content is the main driving force affecting the growth of forest and grassland in Hetao Irrigation District. Figures and Tables | References | Related Articles | Metrics

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Evaluation of the degree of degradation of Xinjiang Tianshan Bayinbuluk grassland in 35 years ZHAO Jian, DENG Chengjun, LI Wenli, ZHAO Jin, GONG Yanming, LI Kaihui 2023, 40 (4):  636-646.  doi: 10.13866/j.azr.2023.04.12 Abstract ( 389 )   HTML ( 17 )   PDF (2576KB) ( 283 )   Many studies on grassland ecosystem degradation have been performed using vegetation coverage or productivity indexes for evaluation. However, it is difficult to comprehensively evaluate different degrees of grassland degradation using a single evaluation index. Taking Bayinbuluk grassland in the Xinjiang Tianshan Mountains as a research object, a remote sensing method for evaluating grassland degradation based on standardized processing sub-index coupling was proposed. The grassland vegetation coverage, average grass layer height, and total grass yield were selected to determine the weight of the three indexes by principal component analysis. The Min-Max standardized method was introduced to construct the grassland degradation index (GDI). Finally, the degree of degradation of Bayinbuluk grassland in the Xinjiang Tianshan Mountains was determined through Landsat image inversion and reasonable classification of the rate of change of grassland degradation index from 1986 to 2021. The results showed that GDIg has the best correlation with NDVI. In 2021, the proportion of undegraded area of Bayinbuluk grassland relative to the total area was 60.51%. The degree of degradation of different grassland types showed clear differences. The spatial distribution showed a trend of basin to mountain degradation. The GDIrs model could be applied to other years through the radiation registration method. The degree of degradation of Bayinbuluk grassland significantly improved from 2000 to 2009 and slightly fluctuated from 2009 to 2021. The results of this research provide robust data support and a theoretical basis for guiding evaluation of the degree of degradation of Bayinbuluk grassland and protecting the grassland ecosystem. Figures and Tables | References | Related Articles | Metrics

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Extraction of desert vegetation information based on five vegetation indices LIANG Boming, LIU Xin, HAO Yuanyuan, CHU Bin, TANG Zhuangsheng 2023, 40 (4):  647-654.  doi: 10.13866/j.azr.2023.04.13 Abstract ( 319 )   HTML ( 29 )   PDF (3331KB) ( 216 )   The aboveground biomass of vegetation in desert areas serves as a crucial indicator for monitoring land desertification and extracting desert vegetation information using remote sensing techniques. In this study, the Minqin County of Gansu Province was selected as the experimental area and Sentinel-2 images were used as the data source. We constructed estimation models (unitary linear, exponential, logarithmic, and binomial models) for the planted index and the aboveground biomass of vegetation, which were measured by us. These models include five vegetation indices: ratio vegetation index (RVI), normalized difference vegetation index (NDVI), difference vegetation index (DVI), soil-adjusted vegetation index (SAVI), and optimized soil-adjusted vegetation index (OSAVI). The aboveground biomass in the study area was estimated using the selected optimal model. The results demonstrated that SAVI had the highest correlation with the aboveground biomass (r = 0.79) compared with RVI, NDVI, DVI, and OSAVI. The binomial model based on SAVI was the best model (R2 = 0.76) for the aboveground biomass estimation in the study area, with higher accuracy (R2 = 0.73, RMSE = 0.12). In the Minqin County, the relatively dense areas of vegetation were mainly distributed in the four major irrigation districts (Hongyashan, Huanhe, Changning, and Nanhu), the surrounding area of Qingtu Lake, and the northwest region of Hongshagang Town, whereas the vegetation in other regions was relatively sparse. The proportions of nonvegetation area <[0.005 kg·(100m2)-1], low vegetation area [0.005-0.2 kg·(100m2)-1], medium vegetation area [0.2-0.5 kg·(100m2)-1], and high vegetation area [>0.5 kg·(100m2)-1] were 66%, 21%, 5%, and 8%, respectively. Figures and Tables | References | Related Articles | Metrics

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Preparation and optimization of leaf protoplasts of Salsola laricifolia XI Yuxin, ZHANG Yuhui, WEN Zhibin 2023, 40 (4):  655-662.  doi: 10.13866/j.azr.2023.04.14 Abstract ( 232 )   HTML ( 3 )   PDF (4020KB) ( 129 )   The release of high-quality protoplasts from plant tissues is a prerequisite for the establishment of other technical systems such as protein subcellular localization, transient expression analysis, and protein-protein interactions. To quickly explore the special functional genes of the C3-C4 intermediate plant Salsola laricifolia, it is essential to establish a simple and efficient method for preparing leaf protoplasts. In this study, the euphylla of axenic tissue culture seedlings of S. laricifolia was used as material to analyze the effects of different concentration ratios of cellulase and isolated enzymes and osmotic pressure on protoplast isolation. The results showed that the true leaves of sterile tissue culture seedlings with a seedling age of 25 days were used for enzymatic hydrolysis in enzymatic hydrolysis solution of 2% cellulase + 0.5% isolated enzyme R-10 + 0.6 mol·L-1 mannitol at 25 °C for 2 h, and W5 The solution was purified at a speed of 800 rpm·min-1, the yield of protoplasts could reach 1.21 × 106, and the viability was 85%. Using the obtained protoplast of S. laricifolia as a receptor, the pBI121-SaNADP-ME4-GFP plasmid vector was successfully transformed by the PEG transformation method, and it was detected that SaNADP-ME4 was located in the chloroplast. In this study, an efficient system for preparing protoplasts from the leaves of S. laricifolia was established, which lays the foundation for mining the special gene functions of this species. Figures and Tables | References | Related Articles | Metrics

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Vulnerability assessment and spatiotemporal distribution of agricultural drought in Northwest China LI Feifei, ZHOU Xia, ZHOU Yuxi 2023, 40 (4):  663-669.  doi: 10.13866/j.azr.2023.04.15 Abstract ( 313 )   HTML ( 30 )   PDF (2441KB) ( 310 )   Northwest China is an important agro-pastoral interleaved region, with a fragile ecology and agricultural production that is extremely sensitive to climate change. Studying the spatiotemporal distribution of agricultural drought vulnerability is key to effectively coping with drought. Based on the IPCC vulnerability assessment framework, considering the impact of evapotranspiration on soil water content, a multi-timescale drought index was incorporated into the index system, and the entropy weight method was used to measure the vulnerability of agriculture to drought; the spatiotemporal distribution of agricultural drought vulnerability and the evolution of cold and hot spot areas were also analyzed. The results show that the vulnerability of agriculture to drought in the northwest region showed a downward trend from 2010 to 2020, with the largest decline in 2010 to 2015, but the regional equilibrium was weakened and there was a “polar” phenomenon. The cold and hot spots of drought vulnerability in the northwest region changed significantly. In 2010, the hot spots were concentrated in the southwest of Xinjiang, and the cold spots were distributed in the north of Xinjiang and Ningxia. In 2020, the hot spot area shifted to the south of Gansu and Qinghai, and showed an outward radiation phenomenon, while the cold spot area was mainly concentrated in northern Xinjiang. Figures and Tables | References | Related Articles | Metrics

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Analysis of the microbial diversity of the surface snow from Glacier No. 1 at the headwaters of Urumqi River, Tianshan Mountains ZHANG Lijuan, DU Han, YUN Fengze, MA Yinghui, ZHANG Xinqiang, Awaguli TUERSUN, MA Zhenghai 2023, 40 (4):  670-680.  doi: 10.13866/j.azr.2023.04.16 Abstract ( 270 )   HTML ( 13 )   PDF (14234KB) ( 74 )   To examine the characteristics of microbial communities in the surface snow samples from the Glacier No. 1 at the headwaters of Urumqi River, Tianshan Mountains (henceforth referred to as “Urumqi Glacier No. 1”) and their relationship with climate and environment, surface snow samples were collected at an altitude of 3549 m in the spring (April, TSX1), and 3770 m (TSX2) and 3800 m (TSX3) in the summer (June) in the region in 2021. The V3-V4 region of 16S rDNA of bacteria, the V4-V5 region of 16S rDNA of archaea, and the ITS2 region of fungi were amplified by polymerase chain reaction (PCR). The products were then subjected to high-throughput sequencing, after which the microbial diversity was analyzed. The results showed that the microbial diversity of the surface snow samples from the Urumqi Glacier No. 1 differed in spring and summer, with the bacterial diversity being higher in spring and lower in summer, while the fungal diversity showed the opposite pattern. Proteobacteria (58.13%-89.10%) and Bacteroidetes (4.24%-40.74%) were the dominant bacteria at the phylum level, while Flavobacterium (2.32%-33.64%) and Polaromonas (0.01%-24.72%) were the dominant bacteria at the genus level. Thaumarchaeota (38.10%-97.55%) was the dominant archaea in the three samples, followed by Nanoarchaeaeota (0%-61.90%) and Euryarchaeota (0%-2.82%). Ascomycota (7.06%-88.43%) and Monoblepharidomycota (36.21%-40.78%) were the dominant fungi at the phylum level, and Aspergillus (0.16%-81.04%) and Rhodotorula (0.02%-8.05%) were the dominant fungi at the genus level. Network interaction analysis showed that the microbial network interaction was dominated by the positive correlation connection (97.3%), and the negative correlation connection accounted for 2.7%, and the interactive relationship tended to be cooperative. In summary, the surface snow microbiota of the Urumqi Glacier No.1 was highly diverse, and the seasonal variation in the microbial community reflects the response of microorganisms to atmospheric circulation in different seasons. Figures and Tables | References | Related Articles | Metrics