分类： 地球科学 >> 地理学 提交时间： 2022-01-30 合作期刊: 《干旱区科学》
摘要： Hyperspectral remote sensing technology is widely used to detect element contents because of its multiple bands, high resolution, and abundant information. Although researchers have paid considerable attention to selecting the optimal bandwidth for the hyperspectral inversion of metal element contents in rocks, the influence of bandwidth on the inversion accuracy are ignored. In this study, we collected 258 rock samples in and near the Kalatage polymetallic ore concentration area in the southwestern part of Hami City, Xinjiang Uygur Autonomous Region, China and measured the ground spectra of these samples. The original spectra were resampled with different bandwidths. A Partial Least Squares Regression (PLSR) model was used to invert Cu contents of rock samples and then the influence of different bandwidths on Cu content inversion accuracy was explored. According to the results, the PLSR model obtains the highest Cu content inversion accuracy at a bandwidth of 35 nm, with the model determination coefficient (R2) of 0.5907. The PLSR inversion accuracy is relatively unaffected by the bandwidth within 580 nm, but the accuracy decreases significantly at 85 nm bandwidth (R2=0.5473), and the accuracy gradually decreased at bandwidths beyond 85 nm. Hence, bandwidth has a certain impact on the inversion accuracy of Cu content in rocks using the PLSR model. This study provides an indicator argument and theoretical basis for the future design of hyperspectral sensors for rock geochemistry.
分类： 地球科学 >> 地理学 提交时间： 2022-01-30 合作期刊: 《干旱区科学》
SONG Yujia
LIU Xijun
XIAO Wenjiao
ZHANG Zhiguo
LIU Pengde
XIAO Yao
LI Rui
WANG Baohua
LIU Lei
HU Rongguo
摘要： The Central Tianshan Block is one of numerous microcontinental blocks within the Central Asian Orogenic Belt (CAOB) that overlies Precambrian basement rocks. Constraining the evolution of these ancient basement rocks is central to understanding the accretionary and collisional tectonics of the CAOB, and their place within the Rodinia supercontinent. However, to date, the timing and tectonic settings in which the basement rocks in the Central Tianshan Block formed are poorly constrained, with only sparse geochemical and geochronological data from granitic rocks within the northern segment of the block. Here, we present a systematic study combining UPb geochronology, whole-rock geochemistry, and the SrNd isotopic compositions of newly-identified granitic gneisses from the Bingdaban area of Central Tianshan Block. The analyzed samples yield a weighted mean Neoproterozoic 206Pb/238U ages of 975911 Ma. These weakly-peraluminous granitic rocks show a common geochemical I-type granite affinity. The granitic gneisses are calc-alkaline and enriched in large ion lithophile elements (LILEs) and light rare earth elements (LREEs), but they are depleted in high field strength elements (HFSEs); these characteristics are similar to those of typical subduction-related magmatism. All samples show initial (87Sr/86Sr)(t) ratios between 0.705136 and 0.706745. Values for ƐNd(t) in the granitic gneisses are in the range from 5.7 to 1.2, which correspond to Nd model ages of 2.01.7 Ga, indicating a role for Mesoproterozoic to Paleoproterozoic rocks in the generation of the granitic protoliths. The documented geochemical features indicate that the protoliths for the gneisses have a similar petrogenesis and magmatic source, which may reflect partial melting of thickened crust with the addition of small amounts of mantle-derived material. The Central Tianshan Block probably constitute part of an exterior orogen that developed along the margin of the Rodinian supercontinent during the Early Neoproterozoic and underwent a transition from subduction to syn-collision compression at 975911 Ma.
分类： 地球科学 >> 地理学 提交时间： 2022-01-30 合作期刊: 《干旱区科学》
摘要： Leaf wetness provides a wide range of benefits not only to leaves, but also to ecosystems and communities. It regulates canopy eco-hydrological processes and drives spatial differences in hydrological flux. In spite of these functions, little remains known about the spatial distribution of leaf wetness under different soil water conditions. Leaf wetness measurements at the top (180 cm), middle (135 cm), and bottom (85 cm) of the canopy positions of rainfed jujube (Ziziphus jujuba Mill.) in the Chinese loess hilly region were obtained along with meteorological and soil water conditions during the growing seasons in 2019 and 2020. Under soil water non-deficit condition, the frequency of occurrence of leaf wetness was 5.45% higher at the top than at the middle and bottom of the canopy positions. The frequency of occurrence of leaf wetness at the top, middle and bottom of the canopy positions was over 80% at 17:00‒18:00 (LST). However, the occurrence of leaf wetness at the top was earlier than those at the middle and bottom of the canopy positions. Correspondingly, leaf drying at the top was also latter than those at the middle and bottom of the canopy positions. Leaf wetness duration at the middle was similar to that at the bottom of the canopy position, but about 1.463.01 h less than that at the top. Under soil water deficit condition, the frequency of occurrence of leaf wetness (4.92%45.45%) followed the order of top>middle>bottom of the canopy position. As the onset of leaf wetness was delayed, the onset of wet leaf drying was advanced and the leaf wetness duration was shortened. Leaf wetness duration at the top was linearly related (R2>0.70) to those at the middle and bottom of the canopy positions under different soil water conditions. In conclusion, the hydrological processes at canopy surfaces of rainfed jujube depended on the position of leaves, thus adjusting canopy structure to redistribute hydrological process is a way to meet the water need of jujube.
分类： 地球科学 >> 地理学 提交时间： 2022-01-30 合作期刊: 《干旱区科学》
摘要： Groundwater plays a dominant role in the eco-environmental protection of arid and semi-arid regions. Understanding the sources and mechanisms of groundwater recharge, the interactions between groundwater and surface water and the hydrogeochemical evolution and transport processes of groundwater in the Longdong Loess Basin, Northwest China, is of importance for water resources management in this ecologically sensitive area. In this study, 71 groundwater samples (mainly distributed at the Dongzhi Tableland and along the Malian River) and 8 surface water samples from the Malian River were collected, and analysis of the aquifer system and hydrological conditions, together with hydrogeochemical and isotopic techniques were used to investigate groundwater sources, residence time and their associated recharge processes. Results show that the middle and lower reaches of the Malian River receive water mainly from groundwater discharge on both sides of valley, while the source of the Malian River mainly comes from local precipitation. Groundwater of the Dongzhi Tableland is of a HCO3CaNa type with low salinity. The reverse hydrogeochemical simulation suggests that the dissolution of carbonate minerals and cation exchange between Ca2+, Mg2+ and Na+ are the main water-rock interactions in the groundwater system of the Dongzhi Tableland. The 18O (from 11.70 to 8.52) and 2H (from 86.15 to 65.75) values of groundwater are lower than the annual weighted average value of precipitation but closer to summer-autumn precipitation and soil water in the unsaturated zone, suggesting that possible recharge comes from the summer-autumn monsoonal heavy precipitation in the recent past (220 a). The corrected 14C ages of groundwater range from 3,000 to 25,000 a old, indicating that groundwater was mainly from precipitation during the humid and cold Late Pleistocene and Holocene periods. Groundwater flows deeper from the groundwater table and from the center to the east, south and west of the Dongzhi Tableland with estimated migration rate of 1.291.43 m/a. The oldest groundwater in the Quaternary Loess Aquifer in the Dongzhi Tableland is approximately 32,000 a old with poor renewability. Based on the 18O temperature indicator of groundwater, we speculate that temperature of the Last Glacial Maximum in the Longdong Loess Basin was 2.4C6.0C colder than the present. The results could provide us the valuable information on groundwater recharge and evolution under thick loess layer, which would be significative for the scientific water resources management in semi-arid regions.
分类： 地球科学 >> 地理学 提交时间： 2022-01-30 合作期刊: 《干旱区科学》
摘要： Long-term monitoring of the ecological environment changes is helpful for the protection of the ecological environment. Based on the ecological environment of the Sahel region in Africa, we established a remote sensing ecological index (RSEI) model for this region by combining dryness, moisture, greenness, and desertification indicators. Using the Moderate-resolution Imaging Spectroradiometer (MODIS) data in Google Earth Engine (GEE) platform, this study analyzed the ecological environment quality of the Sahel region during the period of 20012020. We used liner regression and fluctuation analysis methods to study the trend and fluctuation of RSEI, and utilized the stepwise regression approach to analyze the contribution of each indicator to the RSEI. Further, the correlation analysis was used to analyze the correlation between RSEI and precipitation, and Hurst index was applied to evaluate the change trend of RSEI in the future. The results show that RSEI of the Sahel region exhibited spatial heterogeneity. Specifically, it exhibited a decrease in gradient from south to north of the Sahel region. Moreover, RSEI in parts of the Sahel region presented non-zonal features. Different land-cover types demonstrated different RSEI values and changing trends. We found that RSEI and precipitation were positively correlated, suggesting that precipitation is the controlling factor of RSEI. The areas where RSEI values presented an increasing trend were slightly less than the areas where RSEI values presented a decreasing trend. In the Sahel region, the areas with the ecological environment characterized by continuous deterioration and continuous improvement accounted for 44.02% and 28.29% of the total study area, respectively, and the areas in which the ecological environment was changing from improvement to deterioration and from deterioration to improvement accounted for 12.42% and 15.26% of the whole area, respectively. In the face of the current ecological environment and future change trends of RSEI in the Sahel region, the research results provide a reference for the construction of the ''Green Great Wall'' (GGW) ecological environment project in Africa.
分类： 地球科学 >> 地理学 提交时间： 2022-01-30 合作期刊: 《干旱区科学》
摘要： As an important natural resource, forest land plays a key role in the maintenance of ecological security. However, variations of forest land in the agropastoral ecotone of northern China (AENC) have attracted little attention. Taking the AENC as an example and based on remote-sensing images from 2000, 2010 to 2020, we explored the spatiotemporal variation of forest land and its driving factors using the land-use transfer matrix, spatial autocorrelation analysis and spatial error model. The results showed that from 2000 to 2020, the total area of forest land in the AENC increased from 75,547.52 to 77,359.96 km2 and the changes were dominated by the transformations among forest land, grassland and cropland, which occurred mainly in areas with the elevation of 5002000 m and slope of 1525. There was obvious spatial agglomeration of forest land in the AENC from 2000 to 2020, with hot spots of forest land gathered in the southern marginal areas of the Yanshan Mountains and the low mountainous and hilly areas of the Loess Plateau. The sub-hot spots around hot spots moved southward, the sub-cold spots spread to the surrounding areas and the cold spots disappeared. The spatiotemporal variation of forest land resulted from the interactions of natural environment, socioeconomic and policy factors from 2000 to 2020. The variables of average annual precipitation, slope, terrain relief, ecological conversion program and afforestation policy for barren mountains affected the spatial pattern of forest land positively, while those of annual average temperature, slope and road network density influenced it negatively.
分类： 地球科学 >> 地理学 提交时间： 2022-01-26 合作期刊: 《干旱区研究》
摘要： 频繁的旱灾对甘肃省经济、农业生产造成严重危害，因此利用先进方法建立准确可靠的农业干旱监测模型对该省防旱减灾十分重要。本文基于随机森林（RF）、BP神经网络和支持向量机（SVM）3种机器学习方法，利用甘肃省20022019 年410 月多源遥感数据得到的植被状态指数（VCI）、温度状态指数（TCI）、植被供水指数（VSWI）、降水状态指数（PCI）以及DEM、土壤有效含水量（AWC）和气候类型作为自变量，气象站点以3个月时间尺度的标准化降水蒸发指数（SPEI_3）为因变量，构建3种不同的农业干旱监测模型，分析比较出适用于监测甘肃省农业干旱的最佳模型，同时进一步探究了机器学习方法构建的模型在不同环境下的适用性。结果表明：构建的3种机器学习模型中，随机森林模型的R2平均值高（0.86）且误差小（RMSE为0.40，MAE为0.31），农业干旱的监测效果要优于BP神经网络和支持向量机模型；干燥和湿润两种环境下分别构建的3种机器学习模型在湿润环境中监测能力表现均更优异（R2>0.82），而随机森林模型在两种环境中监测干旱的表现比其他两种模型强。研究结果为甘肃省的农业干旱监测与评估提供了新的科学方法，对农业干旱研究具有重要意义。
分类： 地球科学 >> 地理学 提交时间： 2022-01-26 合作期刊: 《干旱区研究》
摘要： 为探究保护性耕作对陇中黄土高原旱作麦田蓄水保墒效果和产量形成的影响。在连续5 a田间试验的基础上，分析了陇中黄土高原旱作麦田从2019年8月至2020年8月一个耕作周期内，不同耕作措施（传统耕作T、秸秆覆盖TS，免耕NT和免耕秸秆覆盖NTS）对麦田休闲期蓄墒率、水分利用效率、春小麦干物质积累与转运、产量及农艺性状的影响。结果表明：（1）与处理T相比，NTS处理提高了耕层土壤容重和含水量，提高了旱作麦田播种和收获期土壤蓄水量，使水分利用效率提高了48.18%、休闲期蓄墒率提高了5.70%；（2）NTS处理显著提高了春小麦叶面积指数、延缓了叶片的衰老，相比于TS和NT处理，NTS处理下花后干物质积累量分别提高了67.38%和32.14%，花后干物质贡献率分别提高了12.47%和6.61%；（3）NTS处理优化了产量构成因素、显著提高了春小麦产量，使产量达到了3243.30 kg∙hm-2，比传统耕作（T）产量提高了49.32%；NTS处理改善了春小麦群体结构，显著提高了春小麦根系干重、株高和生物量，降低了根冠比，相关性分析表明水分利用效率、叶面积指数、根系干重的提高是促进小麦增产的重要原因。在本试验条件下，免耕秸秆覆盖是实现陇中黄土高原旱作麦田蓄水保墒及节水增产的最优耕作措施、值得在该地区推广应用。
分类： 地球科学 >> 地理学 提交时间： 2022-01-26 合作期刊: 《干旱区研究》
摘要： 农村饮水安全工程是实现全面小康的重大民生工程。研究基于统计数据、实地走访和调查问卷，运用熵权法和模糊数学法，对甘肃省农村饮水安全工程运行管理现状进行评价。旨在建立较全面系统且合理长效的评价体系，同时分析目前饮水安全工程运行管理中存在的问题。结果表明：（1）甘肃省农村饮水安全工程运行管理状况良好，但是省内地区间差异较大，表现为河西5市的评价结果较好，南部各县（市、区）的评价结果相对较差。（2）对评价等级为一般的地区，需要针对政策落实、管理条例更新执行、提升公众维护意识、水管员队伍建设以及供水管道的智能化建设方面进一步优化部署。经过多年的实践探索，甘肃省形成了集中供水工程和分散供水工程并举的特色饮水安全工程建设模式。本研究以期为农村饮水安全工程建设提供切实可行的对策建议，同时也为今后甘肃省乃至全国其他地区的农村饮水安全建设提供技术支撑与科学依据。
分类： 地球科学 >> 地理学 提交时间： 2022-01-26 合作期刊: 《干旱区研究》
摘要： 半干旱地区矿区的土地利用格局在采矿干扰下发生着巨大变化，以全国八大煤炭生产基地之一的山西省大同矿区为研究对象，分析19852015年土地利用类型的时空变化以及影响土地利用变化的驱动因子，构建RF（Random Forest，RF）-FLUS（Future Land Use Simulation，FLUS）模型模拟预测半干旱区矿区未来土地利用变化，结果表明：（1）19852015年，矿区的林地、耕地和水域面积减少，草地和建设用地面积增加。（2）林地、草地分布受气候及距离水系和设施点的距离影响较大；耕地分布受气候、高程及距水域、居民点的距离影响较大；水域分布最重要的影响因子是降水；建设用地分布主要受生产能力和距设施点的距离影响较大。（3）FLUS模型和RF-FLUS模型拟合精度均较高，但RF-FLUS模型比FLUS模型精度更高，更接近实际土地格局变化结果。（4）根据RF-FLUS模型对矿区2025年土地利用变化预测表明，矿区内林地、草地和耕地均呈下降趋势，下降速率变化不大；水域保持不变，建设用地与其他类型（裸地和未利用地）保持稳定上升的趋势。本研究为探究矿区土地格局复杂动态演变机制、探索小尺度土地资源优化路径、促进区域生态健康发展提供有利的科学依据。
分类： 地球科学 >> 地理学 提交时间： 2022-01-26 合作期刊: 《干旱区研究》
摘要： 湿地景观格局能够反映湿地类型的面积变化和空间分布特征，其时空演变有助于理解干扰因子与湿地生态过程之间的作用关系。选择疏勒河中游的库塘湿地、永久性河流湿地和内陆盐沼等5种湿地类型，采用景观格局分析法和主成分分析方法，研究了湿地类型面积、景观指数时空演变及其影响因素。结果表明：（1）19872017年疏勒河中游湿地总面积减少了477.24 km2，其中库塘湿地、永久性河流湿地和内陆盐沼面积分别减少了50.99%、53.28%和35.78%，草本沼泽和沼泽化草甸面积增加了175.26%和21.89%。（2）各湿地在景观水平和类型水平上，斑块密度和景观形状指数呈现波动增大趋势，湿地景观斑块趋向破碎化和零散分布。（3）2017年人口、耕地较1987年分别增加了1.2倍和1.5倍，社会经济发展主要指标对湿地面积变化的解释度为68.89%，气候因子对其的解释度为22.09%。过去30 a人口增长、耕地扩张和水利工程建设导致了疏勒河中游湿地面积减少和景观破碎化。
分类： 地球科学 >> 地理学 提交时间： 2022-01-26 合作期刊: 《干旱区研究》
摘要： 生态脆弱性评价是了解区域生态状况的重要途径，科学评估生态脆弱性等级及变化对区域生态保护与建设，实现区域可持续发展具有重要意义。研究利用SRP模型构建新疆生态脆弱性评价指标体系，结合空间主成分分析方法构建生态脆弱性指数评价模型，分析新疆生态脆弱性时空演变特征。结果表明：（1）20002018年，新疆生态敏感性整体为中度敏感，呈现东南高西北低，主要受景观破碎度和土壤侵蚀程度影响；生态恢复力受植被覆盖度影响较大，整体呈西北高、东南低，变化幅度小，恢复力较弱；生态压力大致呈南、北部的山区和中部绿洲区、山区高、东南低，主要影响因子是人均GDP、农业依赖度和人口密度。（2）20002018年新疆生态脆弱性整体处于中度脆弱到重度脆弱。南、北部植被覆盖度低的地区生态脆弱等级较高，中部高海拔林草丰富地区生态脆弱性等级相对较低；20002018年新疆生态脆弱性综合指数呈现先增长后降低趋势。（3）生态脆弱性主要驱动力方面，人为活动因子的农业依赖度、人口密度、土地垦殖率，自然环境因子的生境质量指数、景观破碎度、景观恢复力指数和年均降水量7个指标是新疆20002018年生态脆弱性变化的主要单因子；生境质量指数、景观恢复力指数、景观破碎度指数、植被覆盖率的变化与区域人类活动的相互作用是促使新疆生态脆弱性的主要驱动力。
分类： 地球科学 >> 地理学 提交时间： 2022-01-26 合作期刊: 《干旱区研究》
摘要： 气候变化及景观格局与生态系统的结构、功能及动态变化密切相关。祁连山生态系统(QLME)是中国重要的生态功能区，基于多元数据，运用遥感及GIS技术，结合InVEST 及GeoSOS-FLUS模型，探索CSET与方法，实现对QLME碳储存的估算。定量估算及分析表明：（1）不同景观类型背景下QLME碳储存具有明显的时空差异性，QLME碳储存最高为草地及林地景观，其次为裸地，而耕地、湿地、建设用地以及农村居民点景观的碳储存较小。19852018年间，QLME碳储存变化总体呈增长趋势，增加了4805.95104 t，年增长率为38.43%。（2）草地景观碳储存占研究区50%以上，其碳储存呈先增后减趋势，林地景观碳储存占总碳储存的11.31%~36.16%，变化幅度较大。（3）基于未来RCP4.5及RCP8.5气候变化情景，QLME碳储存趋于增加，2050年平均碳储存量为3813.38 tkm-2，较2018年增长了8.69%。该研究对于进一步认识碳循环规律及其生态系统稳定性具有重要意义。
分类： 地球科学 >> 地理学 提交时间： 2022-01-26 合作期刊: 《干旱区研究》
摘要： 盐生植物灌溉周期合理制定是对提高干旱区水资源利用效率的关键因素。以食叶草（Rumex hanus by.）细根（d1 mm）为研究对象，采用干旱-复水方法，测定复水后不同时间食叶草细根总根长、根尖数、平均根直径，研究根系增长率、死亡量、根寿命和周转率的变化特征，为制定最佳灌溉周期提供参考依据。结果表明：根长和根尖数在复水后7 d增长幅度最大，10~15 d增长幅度减弱。细根增长率（RER）在复水后第4 d达到最大，第10 d出现显著下降（P），在不同土层（0~20 cm和20~40 cm）和根系直径（0~0.5 mm和0.5~1.0 mm）之间均有极显著差异（P）。细根净生产量（NRP）与RER二者均呈现先增长后降低的规律。复水后15 d，0~20 cm土层和20~40 cm土层的细根存活率分别为3.6%和16.9%，0.5~1.0 mm直径的细根存活率高于0~0.5 mm细根。研究表明复水后细根中位寿命在8.09~13.83 d，20~40 cm土层细根寿命显著高于0~20 cm土层（P）。食叶草细根通过增加20~40 cm土层中0.5~1.0 mm细根应对和适应干旱及复水，从而达到生存目的。综合考虑食叶草生长和农业水资源供给情况，在夏季盐碱地食叶草最佳灌溉周期为10 d。
分类： 地球科学 >> 地理学 提交时间： 2022-01-26 合作期刊: 《干旱区研究》
摘要： 为解决沙冬青（Ammopiptanthus mongolicus）主根长、毛细根少，育苗生根困难、移栽成活率低的林业技术难题，该研究对不同发育程度沙冬青幼苗进行不同强度断根与不同浓度激素处理（IBA）添加，促根培养后测定并分析不同组合处理对沙冬青幼苗根系形态、根系质量及幼苗生长的影响，以探究沙冬青促根成活关键措施，为沙冬青育苗及造林技术提供基础依据。结果表明：（1）断根可促进沙冬青多主根的发生，以及侧根、根总量、幼苗地上地下部分生物量、根冠比、根系活力和根系阳离子交换量（CEC）的增加。其中，幼苗根长达1.5~2.0 cm时断根尖0.5 cm（F2）处理显著促进侧根数、根尖数、分支数、苗木质量指数和根系活力的增加，且根系活力达到断根处理的峰值（较对照显著提高137.70%）；根系CEC在根长达4.5~6.0 cm时断根长1/2（T3）处理时最佳。（2）断根后激素的促根及幼苗生长作用进一步提高。其中，根长1.5~2.0 cm时断根尖0.5 cm+0.075 mgL-1 IBA/0.125 mgL-1 IBA（即P3、P4）处理后根系形态指标（除平均根长外）、根系CEC显著大幅增加；P4处理后幼苗鲜重、根干重、根冠比、苗木质量指数和根系活力最高。P3处理下根中可溶性糖、NSC含量较对照显著增加26.04%和29.07%，根可溶性蛋白含量在P4处理下达到峰值（13.27 mgg-1）。适当断根与IBA添加可通过改变根系形态和提高根系活力一定程度上促进沙冬青根系吸收和养分存储，进而提高根系质量和幼苗生长潜力。
分类： 地球科学 >> 地理学 提交时间： 2022-01-26 合作期刊: 《干旱区研究》
摘要： 对天然分布在巴丹吉林沙漠南缘2种沙地生境（盐渍沙地、普通沙地）芦苇（Phragmites australis）分株种群的构件特征、种群年龄结构、动态特征及种群空间分布格局进行调查，研究表明：（1）盐渍沙地土壤含水量和含盐量都显著大于普通沙地，普通沙地芦苇的株高、生物量以及各构件的生物量整体上都高于盐渍沙地的芦苇，土壤含水量和含盐量是该地区芦苇形态特征差异的重要驱动因素。（2）不同生境样地因土壤条件及种间竞争程度的差异，芦苇种群呈现出不同的年龄结构以及数量动态变化，普通沙地芦苇种群趋向于衰退型，盐渍沙地芦苇种群表现为增长型。（3）普通沙地中芦苇种群空间分布格局在0~4 m尺度上表现为聚集分布，在大于4 m的尺度上表现为随机分布；盐渍沙地的函数值基本都在2条包迹线之间，在0~10 m的尺度内均为随机分布。
分类： 地球科学 >> 地理学 提交时间： 2022-01-26 合作期刊: 《干旱区研究》
摘要： 新疆野苹果（Malus sieversii）是全世界栽培苹果的祖先之一，也是我国重要的战略性植物种质资源，但目前其种群退化严重，对新疆野苹果进行保育需要了解其对氮添加的响应。对不同水平氮添加处理的新疆野苹果幼苗小枝的枝叶大小性状进行单因素方差分析以及异速生长分析，以探明新疆野苹果对氮添加处理的响应，为种群恢复提供理论基础。结果表明：（1）中氮处理对小枝茎的伸长有显著促进作用，且显著降低了野苹果叶面积比率以及叶茎质量比；高氮处理显著降低了野苹果的出叶强度。（2）氮添加对新疆野苹果枝叶之间的增速以及分配格局的影响不是体现在生物量上，而是体现在枝叶形态上，枝长-总叶面积和枝长-叶片数量性状对低中氮处理曲线的增速显著性增长。低、中氮处理组更偏向生长更多叶面积较小而轻的叶片，而高氮处理下的变化趋势不同于低、中氮处理。（3）适当添加氮肥可改善枝叶生长状况和枝叶功能性状相互关系，建议在开展野苹果幼苗原生境移植过程中，考虑生境之间的养分差异并进行针对性氮肥添加。
分类： 地球科学 >> 地理学 提交时间： 2022-01-26 合作期刊: 《干旱区研究》
摘要： 荒漠一年生植物生长速度快、繁殖力强，具有重要的饲用、药用和生态价值。通过文献资料与标本采集信息的考证和野外调查，明确了新疆荒漠一年生植物的物种数量、分布特征及资源类型。结果表明：新疆荒漠一年生植物共有236种，隶属于20科109属，其中藜科为优势科，猪毛菜属为优势属。科可划分为4个分布区类型，以世界广布科为主，占总科数的65%；属可划分为9个分布区类型、8个变型，以温带分布属为主，占总属数的77.98%。在主要荒漠类型中，沙质、砾质和盐质荒漠中一年生植物分别有126种、96种和51种，分别占总种数的53.38%、40.67%和21.61%。在这些物种中，具有饲用和药用价值的资源分别有51种和55种，其中藜科和菊科植物占优势；具有重要生态价值的冬季一年生植物有64种，主要集中在十字花科、禾本科、菊科和紫草科。
分类： 地球科学 >> 地理学 提交时间： 2022-01-26 合作期刊: 《干旱区研究》
摘要： 覆膜是干旱区农田提高作物产量的有效途径，在农业生产中被广泛应用，探究不同作物体系下，土壤温室气体排放对覆膜的响应，对于农田温室气体减排具有重要意义。采用小区试验，对玉米和棉花小区内的覆膜与未覆膜土壤（MM、MN、CM、CN）的温室气体排放量进行原位观测。结果表明：（1）覆膜显著增加了土壤温度与含水量（P）。覆膜处理（MM、CM）土壤CH4排放次数大于未覆膜处理（MN、CN），2种体系中CH4排放通量最高出现在MM与CM处理，分别为63.47 gm-2h-1和16.67 gm-2h-1。（2）N2O最高排放通量分别为MM（616.70 gm-2h-1）与CN处理（244.92 gm-2h-1）。（3）玉米和棉花小区土壤CO2排放通量最大值分别出现在7月（505.93 gm-2h-1）和6月（848.32 gm-2h-1），之后均呈下降趋势。（4）土壤含水量对MM与CM处理的CH4、N2O和CO2排放均产生了显著影响（P）。（5）土壤温度对MM处理CH4排放具有显著影响，MM与CM处理的N2O排放与土壤温度显著正相关，各处理CO2排放均与土壤温度呈显著相关关系（P）。作物种类与地膜覆盖对CO2排放产生了交互作用。（6）MM与MN处理土壤的增温潜势（GWP）显著高于CM与CN处理，增加量为61.83%~74.63%。农田土壤温室气体排放受覆膜和作物的综合影响，膜下土壤温室气体排放对水热因子的响应强于未覆膜土壤。
分类： 地球科学 >> 地理学 提交时间： 2022-01-26 合作期刊: 《干旱区研究》
摘要： 水分是湿地土壤氮矿化过程的主要调控因子，对于湿地土壤中氮素循环过程具有重要作用。以甘南尕海湿地为研究对象，设置4个退化程度（未退化UD、轻度退化LD、中度退化MD和重度退化HD）和4个田间持水量（20% FC、40% FC、60% FC和80% FC），通过室内49 d的好气培养，测定各处理条件下湿地土壤在0~10 cm土层的土壤氮矿化特征。结果表明：（1）在各水分条件下，随着培养时间的延长，4种退化程度土壤氨化速率、硝化速率和净氮矿化速率均呈先增大后减小的趋势。（2）土壤净氮矿化量均值随水分的增加先增大后减小，60% FC条件下，各退化程度土壤净氮矿化量均值变化范围为34.91~44.94 mgkg-1，较20% FC、40% FC和80% FC分别高出22.31~30.29mgkg-1、10.91~19.84 mgkg-1、8.57~19.50 mgkg-1。（3）土壤净氮矿化量均值和净氮矿化速率均值均随湿地退化程度的增加而减小。适宜水分有利于土壤氮矿化，而水分过高不利于土壤氮矿化；同时，湿地退化降低了土壤氮矿化。
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