Subjects: Biology >> Botany submitted time 2022-12-20 Cooperative journals: 《干旱区研究》
Abstract：
One of the important measures to control sand disasters in western desert areas is sand fixation by plants. As a typical desert plant, Alhagi camelorum has important application value. Based on the flow field in the spring, 30 cm of dry Alhagi camelorum was the object of research in this paper. To analyze the characteristics of wind speed and sand deposition, a numerical simulation was used via the fluent and field tests. The results were as follows: (1) the wind-sand flow can be roughly divided into the areas of blocked deceleration, lifting acceleration, turbulent deceleration, and recovery when going through the plant. A weak vortex forms behind the plant, and the height of the recirculation region is related to the distance from the plant. However, they are less than 0.14 m. (2) When the wind speed is 6 m∙s - 1 , plants at a height of 30 cm mainly affect the horizontal wind speed below a height of 0.6 m. The horizontal wind speed at a certain distance behind the plant no longer presents a strict logarithmic distribution with height, but there are two minima, and the acceleration increases rapidly in the height range of 0.3-0.6 m. (3) The windproof efficiency of plants decreases with the increase of wind speed, and this phenomenon becomes more and more obvious the height increases. When the wind speed increases from 6 to 10 m∙s - 1 , the windproof efficiency at a height of 0.3 m within a distance of 5.3 m behind the plant decreases from 40% to 16.56%. (4) The sand accumulation near the plant is different due to the different wind speed. When the wind speed of the incoming flow is low, sand accumulation is mainly concentrated near the front of the plant and within the range between plants. As wind speed increases, sand accumulation moves backward.
Subjects: Biology >> Botany submitted time 2022-12-20 Cooperative journals: 《干旱区研究》
Abstract：
The purpose of this study was to explore the wind erosion evaluation accuracy of the Wind Erosion Prediction System (WEPS). Wind erosion monitoring was carried out on the surface of four different harvest modes in the Ulan Buh Desert Cyperus esculentus planting area in Inner Mongolia, China as follows: full harvest, retain four harvest six, retain six harvest six, and retain intercrop (Cyperus esculentus and Haloxylon ammodendron). Wind erosion monitoring was carried out on the model surface, and the wind erosion prediction results of the WEPS model were verified using the wind erosion data, which was measured twice. The research results showed that compared with full harvesting, the three stubble modes effectively reduced the effect of wind erosion on the surface of the planting area. The intercropping stubble had the strongest wind- proof and sandfixing ability among them, and the six remaining six harvested was the weakest. The surface wind-proof and sandfixing ability was the weakest. With the increased number of remaining stubble, the structural characteristics of wind- sand flow gradually changed from a tortuous shape to the shape of“1”. This can provide a basis for the promotion of planting Cyperus esculentus in northern sandy areas to balance ecological and economic benefits. With the increased height, the sediment load of full harvest, with four remaining six harvested and six remaining six harvested, showed an exponential decreasing trend. The intercropping stubble sediment load showed a logarithmic decrease with the increase of height. The fitting degree decreased gradually, and the distribution law of sediment transport with height changed to a logarithmic direction. There was a certain difference between the WEPS prediction and the measured results. The maximum model value was 10.16 times the measured value, and the minimum was 0.58 times the measured value. The model prediction quality was uncertain, and the prediction effect was poor on the surface with high vegetation coverage. However, there was reasonable consistency as the unit-width sediment load predicted by the model increased as a power function with the increase of the measured value. Overall, the model is feasible in small-scale areas to predict the variation trend of wind erosion with different surface characteristics. However, in the quantitative prediction of wind erosion, the prediction value is less stable. It is necessary to strengthen the research on the model in multi-climate, multi-type surface vegetation coverage, multi-sequence prediction, and other factors related to wind erosion to establish a database that adjusts the model parameters and formulas according to the actual wind erosion environment to improve the universality of WEPS in the future.
Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Soil Science submitted time 2022-08-09 Cooperative journals: 《干旱区地理》
Abstract：为探究黄土高原丘陵区不同植物群落的土壤粒径分布特征。选取草地、山杏纯林、油松纯林和油松山杏混交林0~200 cm土壤为研究对象，采用激光衍射技术测定土壤样品粒度组成，计算土壤粒度参数与分形维数，绘制粒度频率曲线。结果表明：（1）研究区土壤属粉壤土，粉粒含量约占总体的56.58%~71.67%，砂粒约占21.37%~38.71%，黏粒约占3.55%~6.96%。（2）各植物群落内土壤粒度组成随土层深度增加分布较为均一，粒径分布整体分选性均较差，呈极正偏度，峰态尖窄，粒度频率曲线为双峰型，曲线波峰一致。不同植物群落土壤粒径分布差异主要集中在土壤表层0~20 cm（P<0.05）。（3）草地、山杏纯林、油松纯林和油松山杏混交林0~200 cm土壤平均分形维数分别为2.63、2.60、2.61、2.58。分形维数与黏粒含量具有极显著正相关关系（P<0.05），其中，草地土壤分形维数与黏粒的相关性最强。总体来看，黄土高原丘陵区草地土壤粒径分布特征显著优于人工林，本研究结果可为黄土高原的生态重建工作提供理论依据。
Subjects: Geosciences >> Geography submitted time 2021-08-11 Cooperative journals: 《干旱区研究》
Abstract：为了阐明不同土地利用方式对土壤理化性质和生态化学计量特征的影响，以晋西黄土区典型人工混交林地、刺槐纯林地、经济林地、农田、荒草地为研究对象，测定了0~10 cm、10~20 cm、20~30 cm、30~40 cm、40~50 cm、50~60 cm土层的容重、孔隙度以及有机质（TC）、全氮（TN）、全磷（TP）含量，分析土地利用方式与土壤理化性质及生态化学计量特征的关系，以期为土地资源的合理利用与生态服务功能提供依据。结果表明：（1）人工混交林地、刺槐纯林地、经济林地的容重（1.17 g·cm-3、1.19 g·cm-3、1.20 g·cm-3）显著小于农田（1.31 g·cm-3）和荒草地（1.38 g·cm-3），刺槐纯林地TC和TN含量最大（9.94 g·kg-1、0.88 g·kg-1），农田最小（7.26 g·kg-1、0.63 g·kg-1），TP无差异（P>0.05）。随着土层深度的增加，容重逐渐增大，孔隙度逐渐减小，TC和TN逐渐减小，TP保持相对稳定。（2）人工混交林地、刺槐纯林地、经济林地的C:P（25.69、20.51、19.41）和N:P（2.23、1.82、1.58）大于农田（18.57、1.62），C:P和N:P随土层深度的增加而减小，C:N保持稳定。（3）C:N与总孔隙度正相关（P<0.05），C:P和N:P与土壤容重极显著负相关（P<0.01），与总孔隙度、非毛管孔隙度、TC、TN、C:N显著正相关（P<0.05）。通过各土地利用方式的土壤理化性质比较，林地的土壤养分状况显著高于农田，尤其以人工混交林地效果最佳，退耕还林有助于提高土壤质量。因此，在退耕还林还草过程中应多注意树种之间的搭配，而避免大面积营造单一林种。
Subjects: Environmental Sciences, Resource Sciences >> Basic Disciplines of Environmental Science and Technology submitted time 2020-06-21 Cooperative journals: 《干旱区研究》
Abstract：为了研究乌海市沿黄河两岸沙丘风沙流结构差异与冰面风沙特征，开展以黄河西岸-黄河冰面-黄河东岸为路径的风沙观测实验，通过对比分析黄河两岸沙丘风沙流结构、沙尘粒度特征，为黄河沙尘防控问题提供理论依据。研究表明： 两岸沙丘总输沙率均随着高度增加而减小，东岸输沙率垂直拟合优度较西岸差，风沙流比西岸更容易达到非饱和状态。 黄河冰面裂缝滞留沙尘粒径大于0.19 mm，较小颗粒则输移到东岸，东岸沙丘受矿采区粉尘影响，极细砂粒（0.05~0.1 mm）含量增加，极细砂平均含量东岸<西岸，沙尘平均粒径东岸<西岸。 沿黄河两岸沙丘与冰面沙尘的粒度参数峰度均为宽峰态，沙物质来源相似。
Subjects: Environmental Sciences, Resource Sciences >> Basic Disciplines of Environmental Science and Technology submitted time 2020-04-26 Cooperative journals: 《干旱区研究》
Abstract：本文以晋西黄土丘陵沟壑区不同退耕年限（11 a、17 a、22 a、26 a）的油松林为对象，测定不同土层深度（0~60 cm）的土壤养分因子，采用冗余分析（RDA）、回归分析研究了林下草本植物多样性和土壤养分的变化及相互关系。结果表明：① 不同退耕年限油松人工林下共出现8种植物，隶属于6科，8属；随着退耕年限的增加，草本层的物种多样性指数(Margalef、Patrick指数)、丰富度指数(Simpson、Shannon指数)、均匀度指数(Pielou指数)均有所减小，林下草本以万年蒿(Artemisia gmelinii)出现频率最大，其重要值为27； ② 0~60 cm土层的平均土壤有机质和全氮随退耕年限的增加有增加的趋势，具有表聚效应，土壤氨氮、pH、全磷随退耕年限的增加而减小，速效钾随着退耕年限的增加呈先减小后增加的趋势，速效磷变化与速效钾相反；有机质、全氮、pH、速效钾随着土层深度增加而减小；③ 冗余分析表明，林下草本多样性除了受土壤养分影响外，还受其他环境因素影响，土壤养分因子仅能解释41.42%的草本多样性变化；油松人工林下草本层的丰富度指数、多样性指数以及均匀度指数与有机质、全氮均呈负相关，与pH、氨氮、全磷均为正相关；④ 回归分析表明，Patrick指数与有机质、pH、氨氮呈显著乘幂关系(R2为0.743、0.708，P＜0.01)，Margalef指数与有机质、全氮呈线性关系(R2为0.651、0.719)；Shannon指数与pH、氨氮均为线性关系(R2为0.539、0.790)；Simpson指数与有机质为线性关系(R2为0.672)；Pilou指数与有机质、pH、全氮均表现为指数关系(R2为0.631、0.515、0.550)。可以看出土壤养分在一定程度上对草本多样性指数有一定的影响。
Subjects: Environmental Sciences, Resource Sciences >> Basic Disciplines of Environmental Science and Technology submitted time 2020-04-26 Cooperative journals: 《干旱区研究》
Abstract：利用柴达木盆地8个气象站1960—2014年气温和降水的日值数据，分析该区域极端气候的时空变化趋势、周期特征及极端降水对南亚季风和西风环流变化的响应。结果表明：1960—2014年柴达木盆地极端温度总体表现出显著的变暖趋势，变化幅度在空间上表现为由西向东逐渐降低；极端降水频率、降水量和降水强度均有所增加，但中西部地区变化速率远小于东部，仅连续无雨日数通过了显著性检验。平均温差、霜冻日数、冷夜日数的周期特征较弱，结冰日数和生长季日数的显著周期都有变长的趋势，而最低气温的显著周期有变短趋势；极端降水指标均有显著的周期特征，其中连续无雨日数和最大5日降水量的显著周期有变短趋势。同时，南亚季风环流与各极端降水指标间相关振荡的凝聚性很强，具有较强的关联性；而西风环流只与普通日降水强度存在着较强的共振关系。研究结果可为柴达木盆地可持续发展和生态环境保护提供理论与实践参考。
Subjects: Environmental Sciences, Resource Sciences >> Basic Disciplines of Environmental Science and Technology submitted time 2018-06-28 Cooperative journals: 《干旱区研究》
Abstract： 保水剂与其他肥料混施，可以在不同程度上改善土壤的水分和养分条件，促进植物生长。通过将聚丙烯酸钾盐型保水剂与微生物菌剂混合对油松、紫花苜蓿进行盆栽试验，通过对低、中、高（油松：10、20、30 g株-1；紫花苜蓿：20、30、40 gm-2）保水剂和低、中、高（油松：5、10、20 g株-1；紫花苜蓿：15、30、45 gm-2）微生物菌剂混施，分析土壤水分和土壤中速效氮、磷、钾含量变化，及其对土壤水分、养分和植物生长的影响。结果表明：不同处理不同程度地提高了土壤速效氮、磷、钾含量以及土壤含水量。高浓度保水剂和高浓度微生物菌剂混施对一年生油松土壤速效氮促进最显著，低浓度保水剂和中浓度微生物菌剂混施对土壤速效磷、速效钾促进最显著，分别较对照组提高12%、35%和36%；紫花苜蓿高浓度保水剂和高浓度微生物菌剂混施对土壤速效氮、速效磷促进最显著，低浓度保水剂和中浓度微生物菌剂混施对土壤速效钾促进最显著，分别较对照组提高35%、27%和40%。中浓度保水剂和中浓度菌剂混施处理下土壤保水效果最优，而对油松和紫花苜蓿生长的影响达到最佳的分别为低浓度保水剂与低浓度菌剂混施和低浓度保水剂与中浓度菌剂混施。
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