Distribution Characteristics of Soil Total Nitrogen in Low-efficiency Forest Land in the Northern Windy Desert Area of Jingbian County

[Objectives]The paper was to investigate the distribution characteristics of soil total nitrogen in low-efficiency forest land in the northern windy desert area of Jingbian County.[Methods]The distribution of soil total nitrogen in the 0-40 cm soil layer of 5 towns in the northern windy desert area of Jingbian County was studied through field sampling and laboratory detection.[Results]The average soil total nitrogen contents of Hongdunjie Town,Haizetan Town,Huanghaojie Town,Ningtiaoliang Town,Dongkeng Town and windy desert area in the 0-20 cm soil layer were 0.259,0.224,0.242,0.248,0.431 and 0.275 g/kg,respectively.The soil total nitrogen content in Dongkeng Town was higher than those in other towns,while there was little difference among other regions.The average total nitrogen contents in the 20-40 cm soil layer were 0.239,0.285,0.113,0.262,0.349 and 0.241 g/kg,respectively.The soil total nitrogen content in Huanghaojie Town was slightly lower than those in other towns,while that in Dongkeng town was higher.The variation coefficient of soil total nitrogen content in the survey area was greater than 30%,and there was great difference in spatial distribution.With the increase of soil depth,there was little change in soil total nitrogen content,namely the soil total nitrogen contents in 5 towns and windy desert area were not statistically different in the 0-40 cm soil layer.According to the nutrient grading standard of the second national soil survey,the soil total nitrogen content in the survey area was in the deficiency grade.[Conclusions]The research will provide a scientific guidance for the healthy and sustainable development of vegetation in arid regions.

Improving the CoLM in Taklimakan Desert Hinterland with Accurate Key Parameters and an Appropriate Parameterization Scheme

Improving and validating land surface models based on integrated observations in deserts is one of the challenges in land modeling. Particularly, key parameters and parameterization schemes in desert regions need to be evaluated in-situ to improve the models. In this study, we calibrated the land-surface key parameters and evaluated several formulations or schemes for thermal roughness length （z 0h ） in the common land model （CoLM）. Our parameter calibration and scheme evaluation were based on the observed data during a torrid summer （29 July to 11 September 2009） over the Taklimakan Desert hinterland. First, the importance of the key parameters in the experiment was evaluated based on their physics principles and the significance of these key parameters were further validated using sensitivity test. Second, difference schemes （or physics-based formulas） of z 0h were adopted to simulate the variations of energy-related variables （e.g., sensible heat flux and surface skin temperature） and the simulated variations were then compared with the observed data. Third, the z 0h scheme that performed best （i.e., Y07） was then selected to replace the defaulted one （i.e., Z98）; the revised scheme and the superiority of Y07 over Z98 was further demonstrated by comparing the simulated results with the observed data. Admittedly, the revised model did a relatively poor job of simulating the diurnal variations of surface soil heat flux, and nighttime soil temperature was also underestimated, calling for further improvement of the model for desert regions.

Precipitation Pulses and Soil CO_2 Emission in Desert Shrubland of Artemisia ordosica on the Ordos Plateau of Inner Mongolia,China

Precipitation is the major driver of ecosystem functions and processes in semiarid and arid regions. In such waterlimited ecosystems, pulsed water inputs directly control the belowground processes through a series of soil drying and rewetting cycles. To investigate the effects of sporadic addition of water on soil CO2 effux, an artificial precipitation event （3 mm） was applied to a desert shrub ecosystem in the Mu Us Sand Land of the Ordos Plateau in China. Soil respiration rate increased 2.8 4.1 times immediately after adding water in the field, and then it returned to background level within 48 h. During the experiment, soil CO2 production was between 2 047.0 and 7 383.0 mg m^-2. In the shrubland, soil respiration responses showed spatial variations, having stronger pulse effects beneath the shrubs than in the interplant spaces. The spatial variation of the soil respiration responses was closely related with the heterogeneity of soil substrate availability. Apart from precipitation, soil organic carbon and total nitrogen pool were also identified as determinants of soil CO2 loss in desert ecosystems.

Rehabilitation and Sustainable Use Pattern of Rocky-desertified Land in Southwest China’s Poverty-stricken Karst Mountainous Areas——A Case Study in Benggu Township, Xichou County, Yunnan, China

The rocky desert in a karst area directly causes the lack of soil, water and forest, hence leading to the poverty there. In 1990, the villagers from the Muzhe Village in Benggu Township, Xichou County, Yunnan declared a war against rocky desert in an attempt to ask the fields for more yields. They invented a distinctive land rehabilitation and sustainable use pattern called “transforming heavenand earth” that had been practiced in Southwest China’s karst areas. The key mechanism of the pattern was to develop terraced fields with well conserved soil, water and fertility by exploding rocks in the fields, building stone walls, gathering more soil, and improving soil quality and productivity for the fields in combination with building of irrigation facilities and roads, as well as with forestation and agriculture structure adjustment. The purpose of the pattern was to alleviate poverty in the karst areas by improving soil productivity and promoting agriculturaldevelopment. A typical area was studied with the help of Participatory Rural Appraisal (PRA) and the pattern was carried out there for fifteen years, have produced excellent ecological benefits and good economic benefits. Its application in the area approved that it was a sustainable land use pattern for rocky desert areas.

Estimation of the Land Surface Emissivity in the Hinterland of Taklimakan Desert

An accurate accounting of land surface emissivity(ε) is important both for the retrieval of surface temperatures and the calculation of the longwave surface energy budgets.Since ε is one of the important parameterizations in land surface models(LSMs),accurate accounting also improves the accuracy of surface temperatures and sensible heat fluxes simulated by LSMs.In order to obtain an accurate emissivity,this paper focuses on estimating ε from data collected in the hinterland of Taklimakan Desert by two different methods.In the first method,ε was derived from the surface broadband emissivity in the 8–14 μm thermal infrared atmospheric window,which was determined from spectral radiances observed by field measurements using a portable Fourier transform infrared spectrometer,the mean ε being 0.9051.The second method compared the observed and calculated heat fluxes under nearneutral atmospheric stability and estimated ε indirectly by minimizing the root-mean-square difference between them.The result of the second method found a mean value of 0.9042,which is consistent with the result by the first method.Although the two methods recover ε from different field experiments and data,the difference of meanvalues is 0.0009.The first method is superior to the indirect method,and is also more convenient.

Fodder Halophytes for Saline Lands of Kyzylkum Desert

The article is devoted to the economic and biological characteristics of promising desert semi-shrub halophytes (Kochia prostrate, Salsola orientalis, Ceratoides ewersmaniana, Halothamhus subaphyllus, Camphorosma lessingii) to improve saline lands of the Kyzylkum desert.

LAND EVALUATION AND RATIONAL STRUCTURE OF LAND-USE IN DESERT STEPPE AREA IN NINGXIA HUI AUTONOMOUS REGION

Located in the middle and north part of Ningxia Hui Autonomous Region, the desertsteppe area includes the whole of Shizuishan, Huinong, Pingluo, Taole, Helan, Yingchuan,Yongning, Lingwu, Qingtongxia, Wuzhong, Zhongning, and Zhongwei counties and thenorth part of Yanchi, Tongxin counties. This region has an area of 32020 km^2. The popula-

Study on the Land Reclamation of Oilfield of Gurbantunggut Desert in Junggar Basin

The exploration and development of oilfield results in damages to land resources. Along with the further development of petroleum in the Gurbantunggut Desert, the fragile ecological environment and land resource was suffering much more damage. Vegetation degradation and desertification become more prominent. In response to the damage to the fragile ecological environment and oilfield in the Gurbantunggut Desert, limit condition method was used to evaluate the suitability of land reclamation suitability. Results suggested that the main restraining factors for land reclamation were soil condition and water resources. Based on the effect and shortage of oilfield in the Gurbantunggut Desert Oilfield, the reclamation of oilfield in the Gurbantunggut desert was discussed.

Warming effect of desert and its impact on oasis heat resources and agricultural productivity in arid land,China

This paper provides a positive view of the desert, in terms of the warming effect of deserts on oases and the impact of heat re- sources and agricultural production. We use data from experimental sites in the Manas River Basin in China to characterize these relationships. We note that the warming effect of the desert was found to be significant but gradually reduced with in- creased distance of the oasis from the desert. The range of wanning effect is about 100 km, and the improvement in tempera- ture is about 1.8 ℃. Due to this warming effect, the desert serves as the second heat source for the oasis, which represents one important aspect of the ecologic value of the desert. Our results also show the warming effect has a strong spatial impact on agricultural productivity. Crop productivity fell by about 49 kg/ha with every 10 km increase in distance away from the desert. Our results imply that crop suitability must correspond to the warming effect of the desert. More efficient use of heat resources can contribute towards achieving potential productivity.

Driving Force Analysis of Land Cover Change in Ulan Buh Desert Based on Markov Chain

The Ulan Buh Desert has a fragile natural environment, which is in the western part of Inner Mongolia arid climate zone and the farming and animal husbandry ecotone. In order to explore the driving force mechanism of the Land Cover Change, the paper constructed the natural-human driving force model by the Markov Chain based on Landsat MSS 1973, 1977 remote sensing image data, analyzed the naturalhuman driving force contribution rate to the Land Cover Change in Ulan Buh Desert. The results showed that in 1989-2013 the main driving force of the Ulan Buh Desert Land Cover Change is the natural factors, average contribution rate is 89.46%, then is the human driving force, the rate is 10.54%. The natural-human driving force contribution rate for every land cover type is different, in natural part, the minimum rate is saline-alkali land for 45.20%, while the maximum is sandy land(90.63%). The human driving force rate of forest land, grassland and water was negative, it shows that human factors slows down or hinder the growth of this kind of land cover. Because of the humanistic attribute, the natural effect of the cultivated land and construction land was abandoned, the rates of human driving are significantly different: the change of human driving force is 24.94%, while the change of construction land is 62.9%.

Do aeolian deposits and sand encroachment intensity shape patterns of vegetation diversity and plant functional traits in desert pavements?

The effects of sand encroachment on composition,diversity,and functional patterns of vegetation in drylands are rarely studied,and yet addressing these aspects is important to deepen our understanding of the biodiversity conservation.This study aimed to investigate the effect of sand encroachment on plant functional biodiversity of desert pavements(gravel deserts)in the Sahara Desert of Algeria.Plants were sampled and analyzed in three desert pavements with different levels of sand encroachment(LSE)and quantity of aeolian deposits(low,LLSE;medium,MLSE;and high,HLSE).Within the sample-plot area(100 m^(2)),density of every plant species was identified and total vegetation cover was determined.Plant taxonomic and functional diversity were analyzed and compared between LSE.Result showed that 19 plant species in desert pavements were classified into 18 genera and 13 families.Asteraceae and Poaceae were the most important families.The species Anabasis articulata(Forssk)Moq.characterized LLSE desert pavements with 11 species,whereas Thymelaea microphylla Coss.&Durieu ex Meisn.and Calobota saharae(C&D)Boatwr.&van Wyk were dominant species of desert pavements with MLSE(14 species)and HLSE(10 species),respectively.The highest values of species richness and biodiversity were recorded in desert pavements with MLSE,while low values of these ecological parameters were obtained in desert pavements with HLSE.Desert pavements with LLSE were characterized with the highest values of species abundances.Plant communities were dominated by chamaephytes,anemochorous,arido-active,and competitive stress-tolerant plants.The increase in LSE along the gradient from LLSE to HLSE induced significant changes in plant community variables including decreases in plant density,plant rarity,lifeform composition,morphological type,and aridity adaptation.Desert pavements with HLSE favor the degradation of vegetation and trigger biodiversity erosion.

Remote sensing monitoring of the recent rapid increase in cultivation activities and its effects on desertification in the Mu Us Desert, China

The recent ecological improvement in the Mu Us Desert of China, largely attributed to large-scale afforestation projects, has created new opportunities for cultivation activities. However, the subsequent rapid increase in reclamation on desertification land and its impact on desertification have raised concerns. In this study, we first extracted data on cultivated land and desertification land in 1975,1990, 2000, 2005, 2010, 2015, and 2020 through the human-computer interaction visual interpretation method. By overlaying the cultivated land dynamics and desertification land, we subsequently explored the effect of cultivation activities on desertification in the Mu Us Desert during the six periods from 1975 to 2020(1975–1990, 1990–2000, 2000–2005, 2005–2010, 2010–2015, and 2015–2020). The results showed that cultivated land in the Mu Us Desert showed a fluctuating and increasing trend from 3769.26 km~2 in 1975 to 4865.73 km~2 in 2020, with 2010 as the turning point for the recent rapid increase. The main contributors included the large and regular patches distributed in Yuyang District and Shenmu of Shaanxi Province, and relatively smaller patches concentrated in Inner Mongolia Autonomous Region. The increased cultivated land from the reclamation on desertification land was dominated by moderate and severe desertification lands, and the decreased cultivated land that was transferred into desertification land as abandoned cultivated land was dominated by slight and moderate desertification lands. The effect of cultivation activities on desertification reversal(average area proportion of 10.61% for reversed desertification land) was greater than that of the development of desertification(average area proportion of 5.82% for developed desertification land). Nevertheless, compared to reversed desertification land,both the significant increase of developed desertification land during the periods of 2000–2005 and 2005–2010 and the insignificant decrease during the periods of 2005–2010, 2010–2015, and 2015–2020 implied a potential remobilization risk. Therefore, this study provides a significant theoretical reference for the formulation of ecological restoration projects and regional macroeconomic development policies by considering the influence of cultivation activities, to ensure the overall environmental stability and sustainability in desertification land where reclamation and abandonment activities have taken place.

塔克拉玛干沙漠腹地晴天与沙尘暴天气大气边界层对比分析

根据2017、2019年7月塔克拉玛干沙漠腹地GPS探空和地面观测数据,利用位温廓线法等方法,对比分析了沙漠腹地夏季晴天和沙尘暴天气大气边界层结构变化特征。结果表明:晴天和沙尘暴天气大气边界层结构特征显著不同。晴天大气边界层各气象要素垂直分布较为均一,白天对流边界层深厚,高度接近5 km,夜间稳定边界层一般在500 m左右。沙尘暴天气边界层内位温和比湿垂直变化较小,风速较大,可达24.0 m/s,其白天对流边界层在1.5 km左右,夜间稳定边界层在1 km左右。晴天辐射强烈,地表升温迅速,湍流旺盛,是形成晴天深厚对流边界层的主要因素。大尺度天气系统冷平流的动力条件,以及云和沙尘减弱了到达地表的辐射强度是形成沙尘暴天气独特的大气边界层结构的主要因素。

石羊河下游几种典型荒漠植物盐碱地造林适应性研究

为提高石羊河下游盐碱地植被恢复与利用能力,选择梭梭、白刺、柽柳、霸王、泡泡刺、铃铛刺、红砂、黑果枸杞、沙木蓼、塔落木羊柴10种典型荒漠植物为研究对象,在盐碱地采取锯沫+作物碎小秸秆混合物物理覆盖和阻隔法,康地宝、小分子肽氨基酸化学土壤改良剂浇灌法等措施造林,观察几种典型荒漠植物在盐碱地的造林效果。结果表明:1)未处理(对照CK)土壤造林红砂成活率(83.33%)最高,依次顺序为梭梭>铃铛刺>白刺、泡泡刺>黑果枸杞>霸王>沙木蓼>柽柳>塔落木羊柴;栽植穴表层覆盖和底层铺设20 cm锯沫+作物碎小秸秆混合物两个处理各树种成活率保存率存在差异性,相对其他处理成活率和保存率更好,梭梭、白刺、红砂、黑果枸杞、沙木蓼、铃铛刺、泡泡刺7个树种成活率均≥71.43%,柽柳、霸王、塔落木羊柴3个树种成活率在58.33%~23.81%;2)经过3年生长,梭梭、白刺、红砂、黑果枸杞、铃铛刺、泡泡刺6个树种保存率均≥75.47%,相对较高,而柽柳、沙木蓼、塔落木羊柴保存率低,均≤33.30%;3)用康地宝15000倍液、小分子肽氨基酸10000倍液两种盐碱地改良剂单施处理,不同树种成活率和保存率差异性显著,梭梭、白刺、黑果枸杞、泡泡刺成活率均≥61.90%,保存率均≥61.90%,相对较好,两处理对同一树种成活率和保存率差异较大,化学改良剂处理土壤要根据树种,采取相应使用剂量配比;4)5个处理中梭梭、柽柳、铃铛刺、沙木蓼、泡泡刺新梢最大生长量均≥27.26 cm,白刺、黑果枸杞、霸王、塔落木羊柴、红砂新梢最大生长量均≤22.43 cm。综上所述,梭梭、铃铛刺、泡泡刺相对适合做为盐碱地造林的主栽树种,白刺、红砂、黑果枸杞、霸王宜作配置树种;柽柳、沙木蓼、塔落木羊柴在目前雨养条件下,特别是灌溉补水和土壤盐分淋洗的措施不够,不宜在盐碱地造林。

阴山北麓农牧交错区不同弃耕演替时期土壤质量评价

本研究采用空间代替时间的方法,以天然草地作为对照,分析了内蒙古阴山北麓农牧交错带两种不同类型的草原(荒漠草原和典型草原)中的农田及3个不同恢复年限(5年、15年和20年)弃耕地的土壤理化性质,并采用主成分分析法对土壤质量进行综合评价。研究发现,弃耕后,土壤含水率、饱和导水率、毛管孔隙度、非毛管孔隙度、土壤有机碳、全磷、有效磷含量增加;土壤容重、硝态氮、铵态氮、全氮含量逐渐降低;土壤最大持水率指标在荒漠草原呈上升趋势,在典型草原下降;毛管持水率、田间持水率无显著变化(P>0.05);弃耕后,荒漠草原土壤pH降低,典型草原pH升高。基于统计分析的土壤质量得分表明,影响荒漠草原土壤质量的主要因素为土壤有机碳、非毛管孔隙度、容重、全氮,其土壤质量综合得分高低依次为天然草地>弃耕5年>弃耕20年>弃耕15年>农田,影响典型草原土壤质量的主要因子是pH、容重、饱和导水率、有机碳,其综合得分高低依次为天然草地>弃耕15年>弃耕20年>弃耕5年>农田。荒漠草原样地中,农田、弃耕地的土壤质量得分均低于平均水平,典型草原样地中弃耕15、弃耕20年、天然草地的土壤质量得分高于平均水平。由此可知,自发恢复有利于弃耕地的恢复。本研究结果表明,弃耕20年足以使典型草原弃耕地恢复至天然草地状态,但荒漠草原土壤尚未达到其最高土壤质量,需要使用更长的时间进行恢复,且针对荒漠草原与典型草原区需要制定不同的弃耕地土壤质量恢复策略。

荒漠绿洲区土壤生态化学计量特征及驱动因素

通过研究塔里木盆地东北缘绿洲区耕地、园地、林地和裸地中土壤养分元素含量特征,分析了荒漠绿洲区不同土地利用方式对土壤生态化学计量特征的影响,以期为脆弱生态系统土壤质量和功能评价提供参考依据.结果表明:①研究区土壤中TN、SOC含量处于缺乏状态,TP含量处于正常水平,TK含量较为丰富;pH值呈现“西北高、东南低”的分布格局,与其他元素的空间分布格局表现出一定的负相关关系.②TC、SOC、TP、TN含量在耕地中最高,裸地中最低,不同土地利用方式中TK含量差异性不显著.TC、SOC、TN、TP“表聚效应”明显,随土层深度的增加含量减少;pH值随土层深度的增加而增加;TK含量在不同深度变化不明显.③4种土地利用方式中,w(C):w(N)大小依次为裸地>园地>林地>耕地,w(C):w(P)大小依次为园地>林地>裸地>耕地,w(N):w(P)大小依次为园地>耕地>裸地>林地.不同土壤深度上,w(C):w(N)随土层深度的增加而增加,w(N):w(P)随土层深度的增加而减少,w(C):w(P)无明显变化规律.④生态化学计量特征累计方差解释量为91.66%,其中TN对土壤生态化学计量特征的重要性最高,解释量为53.5%.综上,通过提高氮磷复合肥的施用及引种固氮植物等方式,可缓解干旱绿洲区土壤养分元素缺乏的现象.

高分一号与Landsat-8影像在荒漠绿洲过渡带应用对比

针对国产高分一号卫星(GF-1)成像质量是否可以满足区域生态环境监测需求的问题,开展了宽幅多光谱相机(wide field view,WFV)在荒漠绿洲过渡带的成像质量评估研究。从辐射质量、纹理、地类识别精度和归一化植被指数等方面构建评估指标,定量分析了GF-1 WFV和Landsat-8OLI在荒漠绿洲过渡带的成像质量差异。结果表明:GF-1 WFV影像虽然具有较高的空间分辨率,但在辐射质量、地类识别效果、纹理信息及植被指数等方面与Landsat-8OLI相比有一定差距;GF-1 WFV影像的信噪比优势明显,对噪声的抑制效果较好;通过与纹理信息的波段组合,可以有效提高GF-1WFV影像的地物识别效果,缩小与Landsat-8OLI在分类精度上的差距;鉴于明显的光谱范围差异,二者归一化植被指数数据在协同应用的过程中宜分地物类型转换,在西北荒漠绿洲过渡带的国土资源调查、城市规划、农情监测等方面可发挥积极作用。

面向沙戈荒区域新能源消纳的电力系统日前低碳调度策略

针对在沙漠、戈壁、荒漠区域的新能源机组面临消纳和经济性差等问题,提出一种面向沙戈荒区域新能源消纳的电力系统日前低碳调度策略。考虑系统结构的复杂性,采用模型分层的优化方案。上层模型以需求响应(DR)调用成本最小和优化负荷与风光预测总值协方差最大为目标,旨在优化用电负荷曲线,释放电网新能源消纳潜力;下层模型通过协调风电机组、光伏机组、储能电站、火电机组以及上层模型得到的优化负荷,同时将阶梯型的碳交易成本引入到目标函数中,建立多目标“源网储荷”协同低碳调度模型,旨在提高系统运行的经济性,降低系统的碳排放量,提高新能源的消纳能力。最后基于改进的IEEE 30节点系统进行仿真测试,结果验证了模型的有效性。

1987—2022年库布齐沙漠沙化土地时空动态及趋势预测

研究选取1987—2022年遥感影像,基于3S技术,采用NDVI像元二分法模型统计沙化土地时空动态变化;利用地理探测器对影响沙化土地空间变化的影响因子进行定量分析;最后选取PLUS模型预测了2032年沙化土地分布格局。结果显示:①35 a间库布齐沙漠植被覆盖整体呈增长趋势,由13.59%增长到30.43%;自西向东呈现流动沙地到固定沙地的明显划分,北部沿黄段植被居多。②流动沙地面积减少50%;半固定沙地面积增长10%,主要来自流动沙地治理;固定沙地增长89.80%,其中2017年涨幅最大为2.3%。③沙化耕地35 a间由13.98%增长至17.56%,平均每5 a增长约1%~2%;沙化耕地面积增加的30.83%来源于半固定沙地,6.49%来源于流动沙地;沙化耕地弃耕或蚕食导致草地面积增加18.97%。④社会经济因素是库布齐沙漠土地利用变化的主导因子,未来库布齐沙漠将向半固定沙地,固定沙地增加,林地、草地、耕地等资源型用地面积增加的方向发展。研究区沙化土地减少植被覆盖增加,可为后续沿黄段沙漠治理与沙漠工程实施提供借鉴和数据参考。

电-氢-碳耦合促进新能源基地开发模式研究

实现全球“碳中和”,核心是推动能源绿色低碳转型,重要举措是推动新能源大规模基地化开发和高效消纳。针对偏远、水电不足地区新能源基地开发面临的低碳调节手段不足、电网配置和消纳能力有限、“风光火”开发模式降碳难等问题与挑战,提出了基于电-氢-碳协同的新能源基地发展思路和开发模式,将氢基产业发展与新能源开发消纳、煤电灵活低碳转型深度融合,同时结合绿氢、绿氨、绿色甲醇等氢基产品制取工艺的技术发展和调节能力提升,量化分析绿电与绿色氢/氨/甲醇在终端消费市场的竞争力及经济效益,研判不同时期新能源基地开发与氢基产业协同发展的适用模式及应用时序,展望新能源基地电-氢-碳协同开发模式在中国三北地区以及北非等海外地区的应用前景。