Subjects: Geosciences >> Geography submitted time 2024-07-04 Cooperative journals: 《干旱区研究》
Abstract： Severe freezing injury has a significant impact on the growth and development of walnuts (Juglans regia), even leading to plant death in some cases. This study employed the sample method to examine the freezing injury to J. regia in the Wild Walnut Nature Reserve located in the West Tianshan valley in Xinjiang. The distribution characteristics of freezing injury among J. regia were analyzed, and the influence of tree height, crown width, and slope position on the extent of freezing injury was investigated. The results indicated that (1) the total freezing injury rate of J. regia was 87.1%. Among these, the proportion of plants with grade 2 freezing injury was the largest (43.4% ), followed by grade 1 (22.5% ), grade 3 (17.5% ), and grade 4 (3.7% ). (2) the proportion of freezing injury in J. regia plants was the largest in the middle of slope (46.5%), followed by the bottom (35.9%), and the top (4.7%); the proportion of uninjured plants was the maximum at the top of slope (7.4%), followed by the bottom (3.3%), and the middle (2.2%). (3) the proportion of freezing injured plants in the six height classes (H) was most prominent in H1 (43.4% ), followed by H4 (19.5% ), H6 (17.0% ), H5 (15.7% ), H3 (4.3% ), and H2 (0.1%). (4) the proportion of freezing injured plants in the six crown width classes (CW) was most extensive in CW1 (43.4%), followed by CW4 (22.1%), CW3 (20.3%), CW5 (9.5%), CW2 (2.9%), and CW6 (1.8%). (5) the proportion of freezing injured plants in different H and CW classes at the same slope position differed significantly (P<0.05). Plants with grade 1 and 2 freezing injuries were mainly restricted to the middle and bottom of the slope, and those with grade 3 and 4 injuries to the middle. (6) freezing injury in plants was markedly correlated with diameter at breast height (P<0.05) and extremely negatively correlated with CW (P<0.01). Most J. regia plants in the Reserve suffered from freezing injury, and the proportions of freezing injury grades varied conspicuously among the different slope positions，and different H and CW classes. The results of this study provide a scientific reference for the management of the Wild Walnut Nature Reserve and the prevention of freezing injury in J. regia.
Subjects: Geosciences >> Geography submitted time 2023-12-16 Cooperative journals: 《干旱区研究》
Abstract： To reveal the survival strategy of plants in semi- arid coal mining subsidence areas faced with soil erosion stress, 2-3-year-old Artemisia ordosica plants were used as the test materials and in- situ root structure destruction tests were carried out at four levels: severe stress (P1), moderate stress (P2), mild stress (P3), and control (CK). The changes in growth indices, photosynthetic characteristics, and physiological traits of A. ordosica were measured. The results showed that soil erosion stress significantly inhibited the growth rate of A. ordosica, and that the greater the degree of simulated damage, the more significant the growth inhibition. After severe stress, the growth rates of plant height, crown width, branch length, and branch diameter of A. ordosica decreased by an average of 36.91%, 43.90%, 69.76%, and 66.76 %, respectively, compared to control plants. Soil erosion stress also conferred a significant negative effect on the photosynthesis of A. ordosica, and the greater the degree of damage, the stronger the negative effect. After severe stress, the net photosynthetic rate, stomatal conductance, intercellular carbon dioxide concentration, transpiration rate, and chlorophyll content of A. ordosica decreased by 39.86%, 59.26%, 7.82%, 51.55%, and 12.33%, respectively, compared to control plants. After 70 days of erosion stress, the activities of superoside dismutase (SOD), peroxidase (POD), and oxidoreductase (CAT) in A. ordosica initially increased and later decreased, and tended to be stable when compared with the control. The malondialdehyde (MDA) content fluctuated within a certain range. Redundancy analysis showed that the level of SOD activity had the most significant effect on the photosynthetic characteristics of A. ordosica. Comprehensive analysis showed that the root fracture of A. ordosica caused by soil erosion in coal mining subsidence areas will reduce its growth rate and inhibit photosynthesis. However, A. ordosica can maintain its growth by regulating the activity of its antioxidase systems and can therefore be considered to be an ecological restoration plant species due to its excellent resistance and adaptability in erosive areas
Subjects: Geosciences >> Geography submitted time 2021-02-13 Cooperative journals: 《干旱区地理》
Abstract： 区域建设用地开发强度是揭示土地利用效率、社会经济发展水平与国土空间开发状态的 重要指标，对其变化进行监测与管治是优化国土空间开发格局，实现区域可持续发展的重要手 段。构建建设用地开发强度量化模型，以陕西省为例，计算 2000—2015 年县域建设用地开发强度 指数，利用空间自相关分析方法揭示其空间格局和演化特征，并采用最小二乘法（OLS）和地理加权 回归（GWR）模型识别建设用地开发强度格局演化的影响因素。结果表明：（1）2000—2015 年陕西 省建设用地开发强度总体呈现增长态势，内部空间分异显著，高强度区集中在榆林、延安、西安、安 康等地，低强度区集中在咸阳、宝鸡、铜川、商洛、渭南、汉中等地。（2）陕西省建设用地开发强度呈 现出明显的空间集聚状态，热点区稳定分布在西安市辖区及周边区县，冷点区分布在延安南部、咸 阳、铜川、渭南和汉中等部分区域；县域建设用地开发强度逐步提升的同时，区域开发不平衡现象 日益突显。（3）固定资产投资、居民消费水平、财政投入力度、耕地资源和地形条件是影响陕西省建 设用地开发强度空间分异的主要因素，但在不同县域其影响程度大小具有显著差异，且个别因素 的影响具有不稳定性。
Subjects: Geosciences >> Geography submitted time 2020-12-17 Cooperative journals: 《干旱区研究》
Abstract：为研究不同辐射强度对里海盐爪爪不同组织中内生微生物群落的影响，利用Biolog-Eco微平板法结合土壤的理化性质，对新疆不同辐射强度污染区的里海盐爪爪地上部分和根部内生微生物群落代谢活性、碳源利用类型、多样性、主成分和环境因子间的差异进行了分析。结果表明：（1）各处理间代谢活性随培养时间的延长而提高，植物不同组织内生菌群落代谢活性存在明显差异。（2）地上部分样品中的主要菌群为利用碳水化合物类、氨基酸类的微生物；根部样品中的主要菌群为利用碳水化合物类、氨基酸类、羧酸类和多聚物类的微生物。（3）不同辐射强度污染区植物样品及植物不同部位的内生菌群落结构也存在显著差异。尤其在根部样品中，中度辐射污染区的代谢活性和多样性指数显著低于其他污染区。（4）土壤全氮、有机质、速效钾和氯根与微生物群落多样性显著相关，但辐射强度与里海盐爪爪内生菌群落多样性之间没有显著的相关性。本研究揭示了不同辐射强度对植物内生微生物生长代谢、碳源利用及群落多样性的影响，为辐射污染区微生物资源的开发和利用提供了科学依据。
Subjects: Geosciences >> Space Physics submitted time 2017-01-22
Abstract： Wind and temperature data detected by the first meteorological rocket of the Meridian Space Weather Monitoring Project was used tostudy quasi-monochromatic inertia gravity waves over Hainan rocket launch site(19.5°N,109°E).The GW extracted from the stratosphere (troposphere)revealed by rocketsonde is upward(downward) GW,both propagate against the background wind.The intrinsic period, vertical wavelength ，horizontal wavelength ，vertical group velocity ,and horizontal group velocity of Stratospheric(Tropospheric)GWare 20.1 h(22.4 h),9.5 km(4 km), 2900 km(753 km) ,0.0887（0.0298）m/s,and12.7（3.65）m/srespectively. There is a significant difference between and because of the background wind. The ratio and is 305:1(188:1) and 143:1(122:1) for the stratospheric(tropospheric) GW, the former is about 1.62(1.17) times of the latter.
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