Spatiotemporal variation of land surface temperature and its driving factors in Xinjiang,China

Land surface temperature(LST) directly affects the energy balance of terrestrial surface systems and impacts regional resources, ecosystem evolution, and ecosystem structures. Xinjiang Uygur Autonomous Region is located at the arid Northwest China and is extremely sensitive to climate change. There is an urgent need to understand the distribution patterns of LST in this area and quantitatively measure the nature and intensity of the impacts of the major driving factors from a spatial perspective, as well as elucidate the formation mechanisms. In this study, we used the MOD11C3 LST product developed on the basis of Moderate Resolution Imaging Spectroradiometer(MODIS) to conduct regression analysis and determine the spatiotemporal variation and differentiation pattern of LST in Xinjiang from 2000 to 2020. We analyzed the driving mechanisms of spatial heterogeneity of LST in Xinjiang and the six geomorphic zones(the Altay Mountains, Junggar Basin, Tianshan Mountains, Tarim Basin, Turpan-Hami(Tuha) Basin, and Pakakuna Mountain Group) using geographical detector(Geodetector) and geographically weighted regression(GWR) models. The warming rate of LST in Xinjiang during the study period was 0.24℃/10a, and the spatial distribution pattern of LST had obvious topographic imprints, with 87.20% of the warming zone located in the Gobi desert and areas with frequent human activities, and the cooling zone mainly located in the mountainous areas. The seasonal LST in Xinjiang was at a cooling rate of 0.09℃/10a in autumn, and showed a warming trend in other seasons. Digital elevation model(DEM), latitude, wind speed, precipitation, normalized difference vegetation index(NDVI), and sunshine duration in the single-factor and interactive detections were the key factors driving the LST changes. The direction and intensity of each major driving factor on the spatial variations of LST in the study area were heterogeneous. The negative feedback effect of DEM on the spatial differentiation of LST was the strongest. Lower latitudes, lower vegetation coverage, lower levels of precipitation, and longer sunshine duration increased LST. Unused land was the main heat source landscape, water body was the most important heat sink landscape, grassland and forest land were the land use and land cover(LULC) types with the most prominent heat sink effect, and there were significant differences in different geomorphic zones due to the influences of their vegetation types, climatic conditions, soil types, and human activities. The findings will help to facilitate sustainable climate change management, analyze local climate and environmental patterns, and improve land management strategies in Xinjiang and other arid areas.

Effects of Microbial Fertilizers on Soil Improvement and Wheat Growth Characteristics in Saline-alkali Land

[Objectives]This study was conducted to further enrich the research on saline-alkali land improvement,and explore the effects of biological bacterial fertilizers containing Bacillus subtilis and Bacillus velezensis HM-3 in saline-alkali land improvement and crop growth promotion.[Methods]Wheat was planted in saline-alkali land in Huanghua City,Hebei Province,and a mixed application experiment was carried out using biological agents from Hemiao Biotechnology Co.,Ltd.[Results]Compared with the field of control check(CK),water-soluble salts and pH value in the experimental fields decreased,and living bacteria count in the soil increased.Meanwhile,the economic characters of wheat in the experimental fields showed excellent performance,with yields increasing by 39.09%and 27.49%compared with the CK.It could be seen that the application of biological bacterial fertilizers achieved obvious effects of improving saline-alkali soil and increasing wheat yield.[Conclusions]In this study,the effects of biological bacterial fertilizers on saline-alkali land and wheat growth characters were clarified,providing some technical support and theoretical guidance for wheat planting in Huanghua saline-alkali land.

Arbuscular Mycorrhizal Fungal Colonization at Different Succession Stages in Songnen Saline-Alkali Grassland

Arbuscular mycorrhizal(AM)fungi can form symbiosis with 90%of the vascular plants and play important roles in ecosystem.To realize the AM fungal colonization at different succession stages in saline-alkali land and screen AM fungi species with great functions,roots and soil samples were collected from the three succession stages of Songnen saline-alkali grassland.The soil properties and AM fungal colonization were measured,and the fungus distributed extensively in three stages was annotated by sequencing for AML1/AML2 target,subsequently,maize was selected as the host to verify its colonization.The results showed that the soil properties improved with the succession of saline-alkali grassland.The plants’communities of the three stages could be colonized by AM fungi,and the colonization rate of Leymus chinensis(the third stage)ranged from 66.67%to 100%,Puccinellia tenuiflora(the second stage)ranged from 50%to 80%,while the Suaeda glauca(the first stage)was only 35%–60%.Glomeraceae sp1 was identified as the dominant AM fungi species which occurred frequently in the succession of saline-alkali land with the isolation frequency,relative abundance,and importance value of 100%,18.1%,and 59.1%,respectively.The colonization rate of Glomeraceae sp1 in maize ranged from 80%to 87%and similar mycorrhizal characteristics were detected in the roots of P.tenuiflora,S.glauca,and L.chinensis,indicating that Glomeraceae sp1 colonized the samples in the field.The correlation matrix indicated that colonization rate,colonization intensity,and vesicle abundance were closely related to soil conditions most,and they were related significantly to all the soil properties except cellulase activity.Besides,redundancy analysis(RDA)showed that soil properties drove the changes of AM fungal colonization and sporulation.These results will provide theoretical support for realizing the relationship between AM fungal colonization and soil conditions,and also for the exploration of AM fungi species with great functions.

Spatiotemporal evolution and future simulation of land use/land cover in the Turpan-Hami Basin,China

The Turpan-Hami(Tuha)Basin in Xinjiang Uygur Autonomous Region of China,holds significant strategic importance as a key economic artery of the ancient Silk Road and the Belt and Road Initiative,necessitating a holistic understanding of the spatiotemporal evolution of land use/land cover(LULC)to foster sustainable planning that is tailored to the region's unique resource endowments.However,existing LULC classification methods demonstrate inadequate accuracy,hindering effective regional planning.In this study,we established a two-level LULC classification system(8 primary types and 22 secondary types)for the Tuha Basin.By employing Landsat 5/7/8 imagery at 5-a intervals,we developed the LULC dataset of the Tuha Basin from 1990 to 2020,conducted the accuracy assessment and spatiotemporal evolution analysis,and simulated the future LULC under various scenarios via the Markov-Future Land Use Simulation(Markov-FLUS)model.The results revealed that the average overall accuracy values of our LULC dataset were 0.917 and 0.864 for the primary types and secondary types,respectively.Compared with the seven mainstream LULC products(GlobeLand30,Global 30-meter Land Cover with Fine Classification System(GLC_FCS30),Finer Resolution Observation and Monitoring of Global Land Cover PLUS(FROM_GLC PLUS),ESA Global Land Cover(ESA_LC),Esri Land Cover(ESRI_LC),China Multi-Period Land Use Land Cover Change Remote Sensing Monitoring Dataset(CNLUCC),and China Annual Land Cover Dataset(CLCD))in 2020,our LULC data exhibited dramatically elevated overall accuracy and provided more precise delineations for land features,thereby yielding high-quality data backups for land resource analyses within the basin.In 2020,unused land(78.0%of the study area)and grassland(18.6%)were the dominant LULC types of the basin;although cropland and construction land constituted less than 1.0%of the total area,they played a vital role in arid land development and primarily situated within oases that form the urban cores of the cities of Turpan and Hami.Between 1990 and 2020,cropland and construction land exhibited a rapid expansion,and the total area of water body decreased yet resurging after 2015 due to an increase in areas of reservoir and pond.In future scenario simulations,significant increases in areas of construction land and cropland are anticipated under the business-as-usual scenario,whereas the wetland area will decrease,suggesting the need for ecological attention under this development pathway.In contrast,the economic development scenario underscores the fast-paced expansion of construction land,primarily from the conversion of unused land,highlighting the significant developmental potential of unused land with a slowing increase in cropland.Special attention should thus be directed toward ecological and cropland protection during development.This study provides data supports and policy recommendations for the sustainable development goals of Tuha Basin and other similar arid areas.

Initial Exploration on Effect of Saline-alkali Land Rebuilding and Utilization by Fenlong Cultivation

In order to explore the effect of Fenlong cultivation in rebuilding and uti- lization of saline-alkali land, the Fenlong tillage machine and Fenlong technology were invented and put into tests in the saline-alkali land from 2015-2016 in Xinjiang Autonomous Region and Shaanxi province, respectively. The results showed that in Xinjiang, the total salt content in the heavy saline-alkali soil decreased by 31.31% after one season of cotton planting using Fenlong, while cotton yield increased by 48.80%, and the soil salinity level was fallen from ＂severe＂ to ＂moderate＂ level. In Shaanxi, the total salt content in decreased by 42.73% after planting summer corn summer corn the mild saline-alkali land using Fenlong cultivation, while the corn yield increased by 34.83%, and the soil salinity degree was changed from ＂mild de- salination＂ to ＂normal farmland＂. At last, the paper provided the mechanism and reasons for desalination in soil and yield increase by Fenlong cultivation.

Study on the Landscaping Technologies for Coastal Saline-Alkali Land in Tanghai County of Tangshan City

Tanghai County is one of the counties in Tangshan City with the highest saline-alkali degree, with 80% of its land being covered by saline-alkali soils. Through studying landscaping technologies for coastal saline-alkali land in Tanghai County, 3 dominant modes for landscaping engineering in such land were summarized as shallow underground pipe desalination technology, banding soil replacement technology and hole membrane soil replacement technology, which are different in application scope and also in cost (respectively 260, 210 and 170 yuan). 3 landscaping measures were also proposed, including promotion of suitable plant cultivation technologies, application of saline-alkali tolerant plants and biological improvement of soils. To explore economic and practical planting patterns for saline-alkali land, low-cost landscaping tests were conducted from the perspectives of improving landscaping engineering mode and optimizing landscaping measures, and the results showed that it was practical to apply low-cost landscaping patterns, and comprehensive ecological measures should be adopted to realize the sustained utilization of soil.

Dynamics of Saline-alkali Land and Its Ecological Regionalization in Western Songnen Plain, China

As the important reserve land resources for food production,saline-alkali land should play a significant role to ensure the national food security in the context of global food crisis. The western Songnen Plain is one of main distribution regions of saline-alkali land in China,with great potential in agricultural development. In this study,the extent,transformation,spatial distribution and temporal change of saline-alkali land in the western Songnen Plain during 1954–2005 were investigated by using remote sensing and GIS spatial analysis methods. Saline-alkali land change was detected from a temporal series of topographic maps in 1954,satellite images of Landsat MSS in 1976,Landsat TM/ETM in 1988,2000 and 2005 through artificial visual interpretation. The results indicated a significant expansion in saline-alkali land area and aggravation in salinization. The area of saline-alkali land had increased from 401.48×103 ha in 1954 to 1 097.45×103 ha in 2005. While the ratio of light,moderate and serious salinized land areas changed from 6.72︰2.92︰1.00 to 1.25︰1.06︰1.00 in the study period. Grassland,cropland,swampland and water body were the major land use and land cover types from which saline-alkali land transformed. And the secondary salinization occured mainly in Da′an City,Tongyu County,Changling County,Daqing City,Dorbod Mongolian Autonomous County and Zhaoyuan County. Finally,seven large ecoregions and 14 corresponding sub-ecoregions were delineated out based on spatio-temopral dynamic characteristics of saline-alkali land and geo-relational environmental attributes. According to the results,measures of amelioration and ways of development of saline-alkali land in the western Songnen Plain were put forward.

Analysis and assessment of land desertification in Xinjiang based on RS and GIS

The land desertification in Xinjiang was monitored and analyzed based on RS and GIS techniques. Satellite data interpretation was adopted to obtain the general situation of Xinjiang’s land desertification in assistance with the sampling method and on-the-spot investigations. Related monitoring and investigations showed that Xinjiang was facing with severe wide range land desertification, and its desertified area made up 77.08% of the total monitoring area. As for land types, the desertified farmland accounted for 1.92% of the total monitoring area, desertified woodland 4%, desertified grassland 45%, and unused land 49%. Accordingly, as for desertification degrees, non-desertified land occupied 22.92%, weak desertified land 5.69%, medium-degree desertified land 16.58%, severe desertified land 33.19% and super severe desertified land 21.61%. Finally, as for inducing factors, wind-eroded desertification made up 58.23%, water-eroded desertification 8.69%, salinization desertification 6.52% and frozen-melt eroded desertification 3.64%. Xinjiang’s land desertification tended to get worse and the harnessing mission remained hard.

Quantitative Assessment of Impacts of Regional Climate and Human Activities on Saline-alkali Land Changes:A Case Study of Qian'an County,Jilin Province

Interdecadal and interannuat variations of saline-alkali land area in Qian＇an County, Jilin Province, China were comprehensively analyzed in this paper by means of satellite remote sensing interpretation, field flux observations and regional climate diagnosis. The results show that on the interannual scale, the impact of climate factors accounts for 71.6% of the total variation of the saline-alkali land area, and that of human activities accounts for 28.4%. Therefore the impact of climate factors is obviously greater than that of human activities. On the interdecadal scale, the impact of climate factors on the increase of the saline-alkali land area accounts for 43.2%, and that of human activities accounts for 56.8%. The impact of human activities on the variation of saline-alkali land area is very clear on the interdecadal scale, and the negative impact of human activities on the environment should not be negligible. Besides, changes in the area of heavy saline-alkali land have some indication for development of saline-alkali land in Qian＇an County.

Saline-alkali land in the Yellow River Delta: amelioration zonation based on GIS

Soil salinization is one of the major land degradation types and has greatly influenced sustainable agricultural development. Zonation of saline-alkali land is the precondition for effective amelioration. The present situation of saline-alkali land is monitored by remote sensing image processing. Causes for land salinization are analyzed, especially the two key factors, ground water depth and its mineralization degree, are analyzed by using long-term observation data. Previously, zonation of saline-alkali soil was made descriptively and artificially. Based on the present situation of saline-alkali land, ground water depth and ground water mineralization degree, the zonation of saline-alkali land for amelioration in the Yellow River Delta was completed quantitatively. Four different types of saline-alkali land amelioration zones are delineated, namely, easy ameliorated zone, relatively difficult ameliorated zone, difficult ameliorated zone and unfavorable ameliorated zone. Countermeasures for ameliorating saline-alkali soils are put forward according to ecological conditions of different saline-alkali land zones.

Significant changes in arbuscular mycorrhizal community and soil physicochemical properties during the saline-alkali grassland vegetation succession

Arbuscular mycorrhizal(AM)fungi are widely distributed in various habitats,and the community composition varies in response to the changing environmental conditions.To explore the response of community composition to the succession of saline-alkali land,soil samples were collected from three succession stages of Songnen saline-alkali grassland.Subsequently,the soil characteristics were determined and the AM fungi in soil samples were analyzed by high-throughput sequencing.Then,the response relationship between community composition and soil characteristics was studied by Canonical correlation and Pearson analyses.The soil properties improved with the succession of saline-alkali grassland.There was no significant difference in alpha diversity between the first and second succession stage(Suaeda glauca and Puccinellia tenuiflora,respectively),and the microbial community had a dense association network at the third stage(Leymus chinensis);in addition,each succession stage had significantly enriched amplicon sequence variants(ASVs)and functional pathways.All the soil properties except cellulase activity had significant effects on community composition.Furthermore,the pH,organic carbon,organic matter,and sucrase activity significantly correlated with alpha diversity indices.These results provide a theoretical basis for realizing the significant changes in AM fungal community and soil properties during the saline-alkali grassland vegetation succession.

A GIS-based Tupu Analysis of Dynamics of Saline-alkali Land in Western Jilin Province

Based on Tupu theory, this paper studied the dynamic changes, conversion modes, expansion intensity and landscape attributes of the saline-alkali lands in Changling County, Zhenlai County and Da'an City of the western Jilin Province in 1980-2000 with the help of GIS. The results show that the saline-alkali land rather sharply increased in Da'an during 1995-2000; the main conversion processes in the three counties were from grassland to saline-alkali land and from saline-alkali land to grassland; and the typical shapes, spatial expansion speed and mode, and landscape attributes of the saline-alkali land were different in the three counties, which were closely related to local topography, predominant wind orientation, water resources distribution, etc. The corresponding spatial expansion mode was marginality in Changling, random in Zhenlai and more kernels in Da'an, respectively. Landscape attributes also responded to the spatial-temporal dynamic changes of the saline-alkali land and the landscape indices of Da'an fluctuated greatly. The frame of this research may provide fundamental reference for landscape analysis and give some suggestions for regional sustainable development.

The Salt Reduction and Yield Increase Effects of Smashing Ridging Transforming Saline-alkali Land and Its Development Prospects

Using smashing ridging tillage machine and smashing ridging technology invented by the authors, transformation test of saline-alkali land by smashing ridging was conducted respectively in Xinjiang and Shaanxi during 2015 -2016. The results showed, in severe saline-alkali soil of Xin-jiang ,after growing cotton by smashing ridging, total salt in soil decreased by 31.31 %, cotton production increased by 48.80%, and salinity level declined from severe to moderate; in mild saline-alkali soil of Shaanxi, after growing summer corn by smashing ridging, total salt in soil decreased by 42.37%, corn yield increased by 34.83%, salinity degree changed from mild desalination to normal farmland ; in Ningxia, Inner Mongolia 7 Gansu ,Jilin, Henan, Hebei, and so on, smashing ridging tillage practice in different types of saline-alkali land was conducted ; according to the salt reduction and yield increase effects of saline-alkali land after smashing ridging, the development prospect of smashing ridging technique in improvement and application of saline-alkali land was proposed.

Characteristics of land use conversion in soda saline-alkali soil region of central Northeast China

Since the 1970s,the soda saline-alkali soil region,which is located in the semiarid-arid region of the central Northeast China,has experienced drastic climate variability.Meanwhile,human activities and socio-economic development have led to an increase in water consumption.These factors have brought out considerable land use change and a lot of soil salinize-alkalization.The land use types were obtained from remote sensing images interpretation based on Landsat MSS in 1970s,TM,ETM in 1990s and 2010s.The characteristics of land use conversion and its response to climate change and influence of human activities were explored in the study area during 1970-2010.The results include:(1)The land use types had changed significantly,especially farmland and grassland,with annual growth rates of 0.31% and 0.35%,respectively.In terms of the saline-alkali land,the area increased greatly during 1970-1990,and its increase was mainly from grassland.There was a decrease from 1990 to 2010,and the loss of saline-alkali was replaced by farmland and grassland.(2)Climate change in the study area is obvious,showing a trend of decreasing precipitation and increasing temperature.The change of saline-alkali land area is closely related to the precipitation,with R2=0.78,passed a passing the 0.01 significance test.(3)The correlation of land use degree index and human activity index with saline-alkali land was not obvious,and the changes in these indices only reflected the land use patterns.Under sufficient rainfall,the saline-alkali land was developed into farmland by humans,which caused the decrease of the saline-alkali land.Therefore,climate change is the main driving force of land salinization in the study area.

Effects of Soil Improver on Wheat in Saline-Alkali Lands in the Yellow River Delta

Field experiment carried out to test the effects of soil improver on wheat yield and soil physical-chemical properties. The results indicated that soil improver could optimize soil aggregates structure, decrease soil bulk density, soil pH and soil salt content, increase soil organic matter and 1 000-grain weight, thereby enhancing wheat yield. With the increase of soil improver application amount, soil physical-chemical properties became better and wheat yield increased. However, there was no significant difference in the treatments with the application amounts of 3%, 4% and 5%. In addition, the treatment of reducing nitrogen showed no superiority in soil physical-chemical properties and wheat yield, indicating that sufficient nitrogen was essential for the growth of wheat.

Research on Overall Planning and Implementation Evaluation of Land Use of Xinjiang Production and Construction Corps Agriculture-seven Division

Based on methods for evaluating the overall planning and implementation of land use of domestic scholars, a comprehensive and highly-operable index system and evaluating method for land use planning multi-type implementation has been established through selecting multi-type evaluating indicators and applied to the last-round overall planning of land use in Xinjiang Production and Construction Corps Agriculture-seven Division. The obtained comprehensive score was 86.40, indicating that land use overall planning has been excellently coordinated with land, society, economy as well as ecology and has exerted outstanding effect with the rank as "good". The evaluation results are in accordance with actual conditions, which displays that the established multi-type implementation evaluating system of land use overall planning is reasonable with scientific evaluating methods and can be the reference for evaluation of land use overall planning in other regiments and companies of Xinjiang Production and Construction Corps.

清末筹议放垦蒙地及在察哈尔地区的放垦实践

庚子之役后,为了应对统治危机,清廷接受岑春煊的建议解除蒙禁,并派贻谷推行垦务。察哈尔地区属内属蒙古,清廷对该地区的王公牧厂、私垦地进行大规模的放垦和清理,取得显著效果。在近代内忧外患的形势下,清末的垦务活动促进了中国内地与蒙疆地区的一体化,推动中华民族形成嵌入式互动的发展格局,增强了中华各民族之间的凝聚力,使得维护国家统一的内在力量愈发深厚持久。

新疆北部城市碳排放时空分异与碳平衡分区

研究城市土地利用碳排放时空格局与碳平衡分区,对实现碳减排和“双碳”目标至关重要。以新疆北部46个县市为研究区,利用土地利用与能源数据,通过碳排放系数法计算2000—2020年土地利用碳排放,分析碳排放量时空演变情况,对各县市进行碳平衡分区。结果表明:(1)碳排放量呈总体上升趋势,2016—2020年呈现指数型上升的趋势,碳吸收量缓慢下降,碳排放强度先下降后上升,碳排放量远大于碳吸收量。(2)碳排放主要来源于建设用地,天山北坡城市为主要碳排放城市,碳吸收主要来源于草地与林地,伊犁河谷地区、阿尔泰山南部等地城市为主要碳吸收城市。(3)碳排放空间相关性逐渐减弱,热点区集中分布在克拉玛依市附近,冷点区集中分布在伊犁州与阿勒泰地区。(4)依据经济承载力系数、生态承载力系数以及碳排放量划分为碳汇功能区、碳汇优化区、低碳经济区、碳源优化区和高碳控制区五个碳平衡分区。

塔里木河流域土地利用及人类活动强度的时空演化特征研究

[研究目的]人类活动引起的土地利用/覆被变化是全球环境变化的重要组成部分,旱区土地利用对区域水文和生态的影响尤为显著,探究土地利用变化及其对人类活动的响应对西北干旱内陆生态与资源环境可持续发展具有重要意义。[研究方法]基于1980-2018年间共5期遥感影像,结合土地利用动态度、土地利用转移矩阵和人类活动强度指数分析塔里木河流域各水资源分区土地利用变化特征。[研究结果]近40年中,塔里木河流域耕地、建设用地和林地面积分别增加1.58×10^(4)km^(2)、1.2×10^(3) km^(2)和347 km^(2),而草地、未利用地和水域面积分别减少1.33×10^(4)km^(2)、0.32×10^(4)km^(2)和815 km^(2)。各水资源分区中塔里木河干流土地利用类型变化最大,其次为渭干河、阿克苏河和喀什噶尔河流域。自2000年以来,塔里木河流域建设用地当量面积和人类活动强度增加相对较快,特别是2000-2010年间呈显著增长趋势。[结论]塔里木河流域各水资源分区的人类活动强度呈显著的空间差异性。社会经济发展和政策的导向性作用是塔里木河流域土地利用变化和人类活动强度的主要影响因素。

新疆叶尔羌河流域景观生态风险评价及预测

景观生态风险评价是衡量一定范围内生态系统安全的重要手段。以叶尔羌河流域为研究区,综合Markov-PLUS模型与景观生态风险评价指数,分析并预测土地利用与景观生态风险的演变特征及未来多情景下的变化趋势,划分风险重点管理区域。结果表明:(1)2005—2020年叶尔羌河流域耕地、水体与建设用地增加,林地、草地与未利用地减少。2035年Ⅰ情景下土地利用遵循历史发展模式变化。相较于Ⅰ情景,Ⅱ情景下耕地增加,其他地类减少;Ⅲ情景下林地、草地与水体增加,耕地、建设用地与未利用地减少。(2)2005—2035年叶尔羌河流域景观生态风险整体呈上升趋势,空间分布呈“西南部低、东北部高”的特征。风险恶化区主要聚集在海拔较低的冲积平原,风险保持区主要分布在海拔较高的山地与冰川。(3)较Ⅰ情景与Ⅱ情景而言,Ⅲ情景景观生态风险指数均值较小,是未来流域实现生态保护和经济发展双赢的最优情景。(4)叶尔羌河流域东北部冲积平原为稳定高风险区,冲积平原边缘与西部山地为风险易变区,南部山地与冰川为风险增加滞后区。研究结果可为当地景观生态安全格局优化与生态风险防范或降低提供参考。