分类： 地球科学 >> 地理学 提交时间： 2021-04-30 合作期刊: 《干旱区科学》
摘要： Drought was a severe recurring phenomenon in Iraq over the past two decades due to climate change despite the fact that Iraq has been one of the most water-rich countries in the Middle East in the past. The Iraqi Kurdistan Region (IKR) is located in the north of Iraq, which has also suffered from extreme drought. In this study, the drought severity status in Sulaimaniyah Province, one of four provinces of the IKR, was investigated for the years from 1998 to 2017. Thus, Landsat time series dataset, including 40 images, were downloaded and used in this study. The Normalized Difference Vegetation Index (NDVI) and the Normalized Difference Water Index (NDWI) were utilized as spectral-based drought indices and the Standardized Precipitation Index (SPI) was employed as a meteorological-based drought index, to assess the drought severity and analyse the changes of vegetative cover and water bodies. The study area experienced precipitation deficiency and severe drought in 1999, 2000, 2008, 2009, and 2012. Study findings also revealed a drop in the vegetative cover by 33.3% in the year 2000. Furthermore, the most significant shrinkage in water bodies was observed in the Lake Darbandikhan (LDK), which lost 40.5% of its total surface area in 2009. The statistical analyses revealed that precipitation was significantly positively correlated with the SPI and the surface area of the LDK (correlation coefficients of 0.92 and 0.72, respectively). The relationship between SPI and NDVI-based vegetation cover was positive but not significant. Low precipitation did not always correspond to vegetative drought; the delay of the effect of precipitation on NDVI was one year.
分类： 地球科学 >> 地理学 提交时间： 2021-04-30 合作期刊: 《干旱区科学》
Tahani K BAIT SUWAILAM
Abdulrahim M AL-ISMAILI
Nasser A AL-AZRI
L H Janitha JEEWANTHA
Hemesiri KOTAGAMA
摘要： Seawater greenhouse (SWGH) is a technology established to overcome issues related to open field cultivation in arid areas, such as the high ambient temperature and the shortage of freshwater. It adopts the humidification-dehumidification concept where evaporated moisture from a saline water source is condensed to produce freshwater within the greenhouse body. Various condenser designs are adopted to increase freshwater production in order to meet the irrigation demand. The aim of this study was to experimentally investigate the practicality of using the packed-type direct contact condenser in the SWGH to produce more freshwater at low costs, simple design and high efficiency, and to explore the impact of the manipulating six operational variables (inlet air temperature of the humidifier, air mass flowrate of the humidifier, inlet water temperature of the humidifier, water mass flowrate of the humidifier, inlet water temperature of the dehumidifier and water mass flowrate of the dehumidifier) on freshwater condensation rate. For this purpose, a direct contact condenser was designed and manufactured. Sixty-four full factorial experiments were conducted to study the effect of the six operational variables. Each variable was operated at two levels (high and low flowrate), and each experiment lasted for 10 min and followed by a 30-min waiting time. Results showed that freshwater production varied between 0.257 and 2.590 L for every 10 min. When using Minitab statistical software to investigate the significant variables that contributed to the maximum freshwater production, it was found that the inlet air temperature of the humidifier had the greatest influence, followed by the inlet water temperature of the humidifier; the former had a negative impact while the latter had a positive impact on freshwater production. The response optimizer tool revealed that the optimal combination of variables contributed to maximize freshwater production when all variables were in the high mode and the inlet air temperature of the humidifier was in the low mode. The comparison between the old plastic condenser and the new proposed direct contact condenser showed that the latter can produce 75.9 times more freshwater at the same condenser volume.
分类： 地球科学 >> 地理学 提交时间： 2021-04-30 合作期刊: 《干旱区科学》
Abdulrahim M AL-ISMAILI
Moustafa A FADEL
Hemantha JAYASURIYA
L H Janitha JEEWANTHA
Adel AL-MAHDOURI
Talal AL-SHUKEILI
摘要： This study aimed to explore the potential of developing a novel cooling system combining a greenhouse and an earth-tube heat exchanger (ETHE). In this system, greenhouse air is circulated through the underneath soil mass to use the deep-soil cooling effect. This was achieved through the following steps. First, soil temperature profile inside and outside the cultivated greenhouse was monitored for almost one year to study the possibility of using deep-soil coldness for cooling the greenhouse air. Second, a prototype ETHE was built to practically investigate the potential reduction in air temperature as the air flows inside the deep earth pipes. Third, a prototype greenhouse was erected to study the ETHE concept. Results from the first experiment revealed that soil temperature at a soil depth of 2.5 m inside the greenhouse offers good conditions to bury the ETHE. The soil temperature at this soil depth was below the maximum temperature (32°C) that most greenhouse crops can withstand. Results from the prototype ETHE showed a slight reduction in air temperature as it passed through the pipes. From the prototype of the integrated greenhouse and ETHE system, reduction in air temperature was observed as the air passed through the ETHE pipes. At night, the air was heated up across the ETHE pipes, indicating that the ETHE was working as a heater. We concluded from this study that greenhouses in arid climates can be cooled using the ETHE concept which would save a large amount of water that would otherwise be consumed in the evaporative coolers. Further investigations are highly encouraged.
分类： 地球科学 >> 地理学 提交时间： 2021-04-30 合作期刊: 《干旱区科学》
摘要： High temperature and humidity can be controlled in greenhouses by using mechanical refrigeration cooling system such as air conditioner (AC) in warm and humid regions. This study aims to evaluate the techno-financial aspects of the AC-cooled greenhouse as compared to the evaporative cooled (EV-cooled) greenhouse in winter and summer seasons. Two quonset single-span prototype greenhouses were built in the Agriculture Experiment Station of Sultan Qaboos University, Oman, with dimensions of 6.0 m long and 3.0 m wide. The AC-cooled greenhouse was covered by a rockwool insulated polyethylene plastic sheet and light emitting diodes (LED) lights were used as a source of light, while the EV-cooled greenhouse was covered by a transparent polyethylene sheet and sunlight was used as light source. Three cultivars of high-value lettuce were grown for experimentation. To evaluate the technical efficiency of greenhouse performance, we conducted measures on land use efficiency (LUE), water use efficiency (WUE), gross water use efficiency (GWUE) and energy use efficiency (EUE). Financial analysis was conducted to compare the profitability of both greenhouses. The results showed that the LUE in winter were 10.10 and 14.50 kg/m2 for the AC- and EV-cooled greenhouses, respectively. However, the values reduced near to 6.80 kg/m2 in both greenhouses in summer. The WUE of the AC-cooled greenhouse was higher than that of the EV-cooled greenhouse by 3.8% in winter and 26.8% in summer. The GWUE was used to measure the total yield to the total greenhouse water consumption including irrigation and cooling water; it was higher in the AC-cooled greenhouse than in the EV-cooled greenhouse in both summer and winter seasons by almost 98.0%–99.4%. The EUE in the EV-cooled greenhouse was higher in both seasons. Financial analysis showed that in winter, gross return, net return and benefit-to-cost ratio were better in the EV-cooled greenhouse, while in summer, those were higher in the AC-cooled greenhouse. The values of internal rate of return in the AC- and EV-cooled greenhouses were 63.4% and 129.3%, respectively. In both greenhouses, lettuce investment was highly sensitive to changes in price, yield and energy cost. The financial performance of the AC-cooled greenhouse in summer was better than that of the EV-cooled greenhouse and the pattern was opposite in winter. Finally, more studies on the optimum LED light intensity for any particular crop have to be conducted over different growing seasons in order to enhance the yield quantity and quality of crop.
分类： 地球科学 >> 地理学 提交时间： 2021-04-30 合作期刊: 《干旱区科学》
摘要： Groundwater forms the main freshwater supply in arid and semi-arid areas, and contamination of this precious resource is complicated by the slow rate of recharge in these areas. Nitrate contamination of groundwater is a global water quality problem, as it entails threat to human health as well as aquatic ecosystems. Source identification of contamination is the cornerstone and a prerequisite for any effective management program of water quality. Stable isotope composition of the dissolved nitrate (δ15N-NO3– and δ18O-NO3–) has been applied to identify NO3– sources and the main transformation processes in the upper aquifer system (A1/2, A4, and B2/A7 aquifers) in the Wadi Shueib catchment area, Jordan. Moreover, the stable isotope compositions of the groundwater (δ2H-H2O and δ18O-H2O) in conjunction with the groundwater hydrochemistry were integrated to investigate the origin and evolution of the groundwater. Results revealed that groundwater in the study area is fresh and hard-very hard water, and mainly a Ca-Mg-Cl type. NO3– concentration was in the range of 7.0–74.0 mg/L with an average of 37.0 mg/L. Most of the samples showed concentration higher than the natural background concentration of NO3– (5.0–10.0 mg/L). The δ2H-H2O and δ18O-H2O values indicated that the groundwater is meteoric, and of Mediterranean origin, with a strong evaporation effect. The δ15N-NO3– values ranged between 6.0‰ and 11.3‰ with an average of 8.7‰, and the δ18O-NO3– values ranged between 1.6‰ and 5.9‰ with an average of 3.4‰. These values are in conformity with the stable isotope composition of nitrate derived the nitrification of wastewater/manure, and soil NH4. Nitrification and denitrification are the main transformation processes affecting nitrogen species. Statistical analysis revealed no significant differences in the δ2H-H2O and δ18O-H2O values, and δ15N-NO3– and δ18O-NO3– values for the three aquifers (A1/2, A4, and B2/A7), indicating that the groundwater of these aquifers has the same origin, and a common source of pollution.
分类： 地球科学 >> 地理学 提交时间： 2021-04-30 合作期刊: 《干旱区科学》
摘要： Snow cover is an important water source for vegetation growth in arid and semi-arid areas, and grassland phenology provides valuable information on the response of terrestrial ecosystems to climate change. The Mongolian Plateau features both abundant snow cover resources and typical grassland ecosystems. In recent years, with the intensification of global climate change, the snow cover on the Mongolian Plateau has changed correspondingly, with resulting effects on vegetation growth. In this study, using MOD10A1 snow cover data and MOD13A1 Normalized Difference Vegetation Index (NDVI) data combined with remote sensing (RS) and geographic information system (GIS) techniques, we analyzed the spatiotemporal changes in snow cover and grassland phenology on the Mongolian Plateau from 2001 to 2018. The correlation analysis and grey relation analysis were used to determine the influence of snow cover parameters (snow cover fraction (SCF), snow cover duration (SCD), snow cover onset date (SCOD), and snow cover end date (SCED)) on different types of grassland vegetation. The results showed wide snow cover areas, an early start time, a late end time, and a long duration of snow cover over the northern Mongolian Plateau. Additionally, a late start, an early end, and a short duration were observed for grassland phenology, but the southern area showed the opposite trend. The SCF decreased at an annual rate of 0.33%. The SCD was shortened at an annual rate of 0.57 d. The SCOD and SCED in more than half of the study area advanced at annual rates of 5.33 and 5.74 DOY (day of year), respectively. For grassland phenology, the start of the growing season (SOS) advanced at an annual rate of 0.03 DOY, the end of the growing season (EOS) was delayed at an annual rate of 0.14 DOY, and the length of the growing season (LOS) was prolonged at an annual rate of 0.17 d. The SCF, SCD, and SCED in the snow season were significantly positively correlated with the SOS and negatively correlated with the EOS and LOS. The SCOD was significantly negatively correlated with the SOS and positively correlated with the EOS and LOS. The SCD and SCF can directly affect the SOS of grassland vegetation, while the EOS and LOS were obviously influenced by the SCOD and SCED. This study provides a scientific basis for exploring the response trends of alpine vegetation to global climate change.
分类： 地球科学 >> 地理学 提交时间： 2021-04-30 合作期刊: 《干旱区科学》
摘要： Snow avalanches are a common natural hazard in many countries with seasonally snow-covered mountains. The avalanche hazard varies with snow avalanche type in different snow climate regions and at different times. The ability to understand the characteristics of avalanche activity and hazards of different snow avalanche types is a prerequisite for improving avalanche disaster management in the mid-altitude region of the Central Tianshan Mountains. In this study, we collected data related to avalanche, snowpack, and meteorology during four snow seasons (from 2015 to 2019), and analysed the characteristics and hazards of different types of avalanches. The snow climate of the mid-altitude region of the Central Tianshan Mountains was examined using a snow climate classification scheme, and the results showed that the mountain range has a continental snow climate. To quantify the hazards of different types of avalanches and describe their situation over time in the continental snow climate region, this study used the avalanche hazard degree to assess the hazards of four types of avalanches, i.e., full-depth dry snow avalanches, full-depth wet snow avalanches, surface-layer dry snow avalanches, and surface-layer wet snow avalanches. The results indicated that surface-layer dry snow avalanches were characterized by large sizes and high release frequencies, which made them having the highest avalanche hazard degree in the Central Tianshan Mountains with a continental snow climate. The overall avalanche hazard showed a single peak pattern over time during the snow season, and the greatest hazard occurred in the second half of February when the snowpack was deep and the temperature increased. This study can help the disaster and emergency management departments rationally arrange avalanche relief resources and develop avalanche prevention strategies.
分类： 地球科学 >> 地理学 提交时间： 2021-04-23 合作期刊: 《干旱区研究》
摘要： 基于新疆棉铃虫生物学特性和多年的种群动态趋势，并在收集棉花种植面积、产量、棉花市场价格及棉铃虫防治费用等相关数据的基础上，采用种群模拟模型（CLIMEX模型）并结合随机模拟方法（@RISK软件），评估不同场景下棉铃虫对新疆棉花产业造成的潜在经济损失。棉铃虫种群模拟表明：随着未来气候变化，新疆棉铃虫的周增长指数（GIw）会增加，棉铃虫越冬蛹羽化的日期明显提前，危害风险可能增加；2种模拟场景结果表明，抗虫棉能有效地降低棉铃虫造成的危害，减少单位面积防治成本。建议新疆相关部门未来可通过种植抗虫棉与害虫综合治理策略（IPM）的有机结合，来减少棉铃虫及次要害虫造成的损失。
分类： 地球科学 >> 地理学 提交时间： 2021-04-23 合作期刊: 《干旱区研究》
摘要： 为了阐明覆膜滴灌棉田地膜残留对棉花生长的影响，结合绿洲覆膜滴灌棉田残膜累积特点，设计对应覆膜年限为5 a、10 a、15 a、20 a、25 a、30 a共6个不同残膜累积梯度，利用桶栽试验，分析了不同覆膜年限棉田中残膜累积对棉花生长和产量的影响。结果表明：残膜对棉花地上部株高和叶面积影响显著，随残膜量的增加株高和叶面积逐渐降低，当覆膜滴灌20 a时各时期株高和叶面积均显著减小。覆膜滴灌20 a时残膜量的增加开始显著降低棉花地下部根系指标，与CK相比，覆膜滴灌20 a的根长密度降低8.2%，根表面积密度降低10%，根体积降低7.2%，根系直径降低19.4%。残膜量与棉花干物质积累量和产量呈显著负相关，覆膜滴灌20 a后相比于CK，地上部干物质量降低20.3%，根部干物质量降低38.4%；棉花产量相比新疆近5 a地区平均单位面积产量降低10.96%。残膜量的增加对棉花的正常生长影响显著，当覆膜滴灌年限达到15~20 a时，棉花的生长与根系指标和产量显著降低。研究结果可为新疆滴灌棉田可持续发展提供理论依据。
分类： 地球科学 >> 地理学 提交时间： 2021-04-23 合作期刊: 《干旱区研究》
摘要： 对2017年乌鲁木齐市的气象参数及大气污染物的浓度进行了统计分析，探究了大气污染物的浓度变化特征，运用轨迹聚类分析、潜在源贡献函数（PSCF）和浓度权重轨迹法（CWT）研究了乌鲁木齐市PM2.5的传输路径和潜在源区。结果表明：乌鲁木齐市大气超标污染物主要为PM2.5和PM10，除O3外各污染物的浓度均是采暖期高于非采暖期，温度低、风速小、相对湿度大、乌鲁木齐市三面环山、逆温天气是造成采暖期颗粒物污染严重的重要原因；PM2.5区域传输主要来自西北方向，在采暖期受来自尼勒克县、沙湾县、呼图壁县、阜康市的短距离传输气团影响很大；PM2.5潜在源区主要集中于阜康市、和静县、沙湾县、昌吉市、沙湾县、吉木萨尔县、玛纳斯县，乌鲁木齐市PM2.5浓度同时受外来污染物输入和本地污染源排放的影响。
分类： 地球科学 >> 地理学 提交时间： 2021-04-23 合作期刊: 《干旱区研究》
摘要： 针对高分六号WFV数据应用研究基础相对薄弱，准噶尔山楂遥感识别在算法、数据源等方面存在不足的问题，联合GF-6 WFV和ZY-3号影像数据提取多种分类特征，基于面向对象分割、特征选择、特征重要性评价与组合以及多分类器联合等方法对准噶尔山楂的遥感识别开展研究，提出优选特征辅助下的面向对象多分类器组合的准噶尔山楂识别算法。研究表明：（1）GF-6 WFV数据能够很好的对准噶尔山楂进行识别，特别是新增的红边波段对树种识别具有重要作用；（2）面向对象分割、特征选择和多特征组合都对准噶尔山楂识别的精度具有正向提升作用；（3）多分类器组合算法能够弥补单一分类器表征力差异造成的误差，显著提高识别精度和算法的稳定性。
分类： 地球科学 >> 地理学 提交时间： 2021-04-23 合作期刊: 《干旱区研究》
摘要： 雪岭云杉林是新疆天山北坡山地森林中广泛分布的优势种，探讨林分密度对天山雪岭云杉林器官生物量分配格局和树高-胸径异速生长的影响，对于阐明雪岭云杉林生物量在不同环境中的适应具有重要意义。通过分析在不同林分密度（≤300株·hm-2、300～450株·hm-2、450～600株·hm-2、＞600株·hm-2）下雪岭云杉林（Picea schren⁃kiana）的生长特性，研究林分密度对雪岭云杉林器官生物量分配格局及树高-胸径异速生长的影响。结果表明，随着林分密度增加，雪岭云杉林各器官平均生物量均降低；树干和树根生物量占比增加，树枝生物量占比减少，树叶和树皮生物量占比变化不显著；雪岭云杉林树高和胸径均随林分密度的增加而降低。此外，雪岭云杉林树高（H）和胸径（D）间具有显著的异速生长关系，其中树高-胸径（H-D）的最优异速生长方程为：y = 2.312 × x0.900（R2=0.761，P<0.01）；随着林分密度增加，雪岭云杉林lgH-lgD 呈现出复杂非线性异速生长关系，该关系的显著性受林分密度变化呈现逐渐降低的趋势，这表明林分密度通过雪岭云杉林对生长资源的竞争影响各器官的生长发育。研究结果可为雪岭云杉林的可持续经营与管理提供理论依据和数据支撑。
分类： 地球科学 >> 地理学 提交时间： 2021-04-23 合作期刊: 《干旱区研究》
摘要： 基于1982—2015年GIMMS NDVI3g.v1数据，结合站点气象数据，采用趋势分析、变异系数、Hurst指数及偏相关分析等方法，探讨了科尔沁沙地植被覆盖的时空特征、气候响应及未来趋势。结果表明：（1）科尔沁沙地34 a植被覆盖呈缓慢增加趋势，每10 a增速为0.23%。植被覆盖变化整体上可分为“三升”（1982—1999年、2000—2004年、2008—2012年）和“三降”（1999—2000年、2004—2007年、2012—2015年）的趋势，其中最大值出现在1999年，最小值出现在2009年。（2）科尔沁沙地植被覆盖格局呈“南北高，中间低”的分布特征。以“西拉木伦河—新开河”为界线，北部地区植被变化趋势以退化为主，南部地区以改善为主。（3）科尔沁沙地变异系数西高东低，地域性差异明显。低波动变化区域主要分布在北部海拔较高地区（占5.52%），其植被类型主要为针阔混交林。（4）科尔沁沙地植被变化的同向特征强于反向特征，持续退化和持续改善区域分别占61.48%和37.03%。降水是影响研究区植被变化的主要因素。
分类： 地球科学 >> 地理学 提交时间： 2021-04-23 合作期刊: 《干旱区研究》
摘要： 为了实现基于单独光学遥感数据对科尔沁沙丘草甸相间地区土地利用与覆被(LULC)类型的识别，选用2018年64景Sentinel-2影像，结合影像分割技术，利用植被物候信息和生境特征，建立了基于群落水平的LULC决策树识别规则，总体分类精度为0.91，Kappa系数为0.89。分类结果显示：研究区旱地分布面积最大，占33.79%，灌木群落次之，占25.03%，高多样性半灌木群落和乔木林相近，分别为14.54%和10%，低多样性半灌木群落、草甸地和流动沙地分别占5%左右，剩余类型的总占比小于5%。该方法不仅可以准确反映研究区覆被类型的空间分布情况，还能给出不同覆被类型的生长发育状况，可为该区域物质循环研究提供基础数据，同时为该区域历史LULC识别提供阈值参考。
分类： 地球科学 >> 地理学 提交时间： 2021-04-23 合作期刊: 《干旱区研究》
摘要： 全球气候变暖导致干旱趋势加重，对西北干旱半干旱区农牧业生产造成严重威胁。考虑到陕西省神木市具有典型的黄土高原地貌特征，以及降水对复杂地貌背景区干旱的决定性作用，本研究应用高精度的GPM（GlobalPrecipitation Measurement）降水数据，建立土壤干旱遥感监测模型，开展能够揭示土壤相对湿度的应用分析研究。结果表明：结合GPM降水数据建立的综合植被、温度和降水的土壤干旱遥感监测模型，能准确的揭示神木市土壤表层10 cm相对湿度，模型中温度和降水的权重较高，体现出温度和降水对区域干旱的主导作用；神木市作物生长季旱情整体处于轻旱强度，平均发生频率为64.44%，且中旱>轻旱>重旱>特旱，干旱强度和发生频率均呈现出西北高东南低的空间分异特征；4—10月干旱强度整体由轻旱发展至重旱，最后干旱消失。季节上，神木市春旱现象严重，且以中旱发生频率最高。2001—2019年神木市旱情呈略微减轻趋势，但红碱淖湿地因年均气温和年蒸发量明显上升，干旱情况加剧。
分类： 地球科学 >> 地理学 提交时间： 2021-04-23 合作期刊: 《干旱区研究》
摘要： 为探究新疆伊犁河谷西北部地下水化学特征及成因，运用数理统计以及Piper三线图、Gibbs图、离子比图等方法，对2018年伊犁河谷西北部地下水取样监测数据进行分析。结果表明：（1）研究区地下水属于总硬度偏高的弱碱性水，地下水化学组分含量整体变异性不大，主要阳离子为Ca2+,主要阴离子为HCO3-。（2）地下水水化学类型以HCO3-Ca、HCO3·SO4-Ca、HCO3·SO4-Ca·Mg、HCO3·SO4-Ca·Na和HCO3-Ca·Mg型为主。（3）研究区地下水化学组分主要受岩石溶滤作用控制，蒸发-浓缩作用及阳离子交换作用对地下水化学组分有一定的贡献，个别地下水水样点可能受到人为活动的影响。（4）地下水中的Na+、Cl-和SO42-主要来自岩盐、石膏等蒸发岩的溶解，Ca2+和Mg2+主要来自方解石、白云石和石膏等矿物溶解。
分类： 地球科学 >> 地理学 提交时间： 2021-04-23 合作期刊: 《干旱区研究》
摘要： 河川径流演变特征对流域水资源管理及开发利用具有重要的意义。基于和田河源流乌鲁瓦提站和同古孜洛克站1957—2018年62 a长时间径流实测数据，采用线性趋势、Mann-Kendall趋势检验和重标极差分析法，从年代际、年际、季节及月份4个时间尺度分析了和田河源流区径流演变特征。结果表明：乌鲁瓦提站和同古孜洛克站的径流年代际变化特征一致，均经历了“平水年-偏丰水年”；乌鲁瓦提站和同古孜洛克站年径流量均呈现不显著增加趋势，径流序列的突变点均为2009年，年径流均在一定时间内持续增加；乌鲁瓦提站夏秋季径流量变化对年径流量影响最大，同古孜洛克站夏季径流量对年径流影响最大；径流量年内分配不均匀，主要集中在5—9月，占比在86.11%～90.86%，呈“冬枯夏洪”。
分类： 地球科学 >> 地理学 提交时间： 2021-04-23 合作期刊: 《干旱区研究》
摘要： 为了探究荒漠草原优势植物对水分和养分输入的响应特征和适应规律，通过设置2个水分水平（自然降雨、水分添加）和3个养分水平（无养分添加、N添加、NPK添加），共6个处理，研究水分与养分添加对荒漠草原优势植物沙生针茅（Stipa glareosa）生长、生理及其敏感性的影响。双因素方差分析结果表明：水分主效应、养分主效应及水分和养分的交互作用对沙生针茅的生长生理特性具有显著影响（P<0.05）。水分添加显著增加了沙生针茅的叶片鲜重、干重、株高和相对电导率，降低了SOD酶活性；养分添加增加沙生针茅的叶面积，N添加增加了丙二醛含量，NPK添加降低了叶绿素a/b（Ca/Cb）和SOD酶活性；水分和养分的交互作用对叶面积、叶片厚度、叶绿素a（Ca）、脯氨酸、蛋白质含量和SOD酶活性具有显著影响。敏感性分析表明，叶面积和Ca含量对同时添加水分和NPK处理较为敏感，而Ca/Cb对水分添加处理更为敏感。综上所述，沙生针茅可以通过改变特定的生长生理特性适应水分和养分的变化，这对于揭示荒漠草原植物对全球变化的响应机制具有重要意义。
分类： 地球科学 >> 地理学 提交时间： 2021-04-23 合作期刊: 《干旱区研究》
摘要： 为研究凋落物在极端干旱区的分解规律，利用凋落物分解袋法，以塔克拉玛干沙漠南缘策勒绿洲地区优势物种花花柴（Karelinia caspia）和胡杨（Populus euphratica）叶凋落物为研究对象，模拟自然状态，分别在3种生境下：土壤表层0 cm、土壤埋深2 cm、悬挂1 m进行凋落物分解试验，探究不同分解位置下的凋落物质量分解和碳（C）、氮（N）元素含量释放特征。结果表明：不同植物的质量损失率在不同分解位置处理下均存在显著差异，土壤表层0 cm处理下凋落物质量损失显著高于悬挂1 m和土壤埋深2 cm。至凋落物分解试验结束，花花柴质量损失率依次为：土壤表层0 cm（19.91%）>悬挂1 m（15.99%）>土壤埋深2 cm（12.35%）。胡杨质量损失率依次为：土壤表层0cm（24.15%）>悬挂1 m（13.44%）>土壤埋深2 cm（8.72%）。在整个分解过程中，两种植物叶凋落物N含量呈富集现象，C含量呈释放状态。在不同分解位置下，N元素富集量和C元素量损失差异显著，土壤表层和土壤埋深2 cm凋落物N元素富集量均小于悬挂1 m凋落物，C元素损失量均大于悬挂1 m凋落物。Olson指数衰减模型对凋落物质量残留率进行拟合，两种植物的分解常数k 值大小排序均为：土壤表层0 cm>悬挂1 m>土壤埋深2 cm。凋落叶质量残留率多因素方差分析表明在不同分解时间和不同分解位置对凋落物质量残留率影响显著（P<0.01）。在极端干旱区，掩埋条件不是驱动凋落物分解的主要因素，影响凋落物分解的因素主要是光降解。
分类： 地球科学 >> 地理学 提交时间： 2021-04-23 合作期刊: 《干旱区研究》
摘要： 植物对干旱的适应能力不仅包括干旱胁迫期间的抗旱能力，也包括复水之后的恢复能力，因此，开展干旱复水条件下植物幼苗生长及根系形态特征变化规律的研究，对揭示植物抗旱生理机制具有重要意义。通过盆栽控水进行干旱胁迫和复水处理，测定了干旱-复水条件下红砂幼苗基径、株高、生物量以及根系形态指标，分析了其生长、生物量分配及根系形态特征对干旱-复水的响应。结果表明：（1）与适宜水分相比，干旱胁迫下红砂幼苗基径和株高相对增量以及地上、地下和总生物量显著减小（P<0.01），各干旱胁迫下红砂幼苗基径相对增量随时间增加呈现减小的变化趋势；复水后中度和重度胁迫处理下红砂幼苗基径和株高相对增量较大，表明红砂幼苗在较严重的干旱胁迫下复水时，其地上部分恢复生长更快；（2）与适宜水分相比，干旱胁迫下红砂幼苗比根长显著增加（P<0.01），表明红砂幼苗可通过根系伸长生长以适应干旱胁迫；复水后重度干旱胁迫处理下红砂幼苗总根长、根表面积和总根体积减小，而红砂幼苗根系直径显著增加（P<0.01），表明红砂幼苗在重度胁迫处理下根系恢复力减弱。综上所述，干旱胁迫期间红砂幼苗通过加快基径和根系的生长储存更多物质来应对胁迫环境，从而表现出较强的抵抗力；复水后红砂幼苗通过加快地上部分生长和根系直径与比根长的增大来恢复生长，有助于提高其较强的恢复能力。
点击量
点击量
下载量
评论
