Responses of subshrub sagebrush rangeland in North-Western China to changes in livestock numbers and rainfall over 10 years (2004–2013)

Seriphidium transiliense, or subshrub sagebrush, is one of the most important forage resources for livestock in many arid lands, but such resources have been threatened by overgrazing for a long time. A 2013 vegetation survey of an original sagebrush rangeland (2400?ha) in the Tianshan Mountains revealed that nearly half of the area once under sagebrush has been replaced by annual species. This is due to the continual and rapid increase in livestock numbers over the past 30?years. Three smaller sites with different grazing scenarios: no grazing (Site N), a decline (Site 1), and an increase (Site 2) in livestock numbers, were selected to monitor recent changes (from 2004 to 2013) in vegetation biomass and the degree of dominance by sagebrush. Supplanting happened at Site 2 but little occurred at Site 1. There were significant differences between Site 2 and Site 1 in standing biomass in Spring and Summer, but no significant differences in Summer between Site 1 and Site N. The supplanting of sagebrush marks the completion of a dynamic process – in which rainfall plays a crucial role – of damage to sagebrush from heavy grazing in drought years and its rehabilitation by light grazing in some good years. Plant biomass loss was greatest when the land was first subjected to heavy grazing. Sagebrush tends to exist as a sole-dominant species rather than a companion species in sagebrush communities. This suggests that sagebrush continued to survive in pockets where grazing pressure had declined.     

Marine-Derived Chitosan Nanoparticles Improved the Intestinal Histo-Morphometrical Features in Association with the Health and Immune Response of Grey Mullet (Liza ramada)

Marine-derived substances are known for their beneficial influences on aquatic animals’ performances and are recommended to improve intestinal health, immunity, and anti-oxidative status. The present study investigates the role of chitosan nanoparticles on the intestinal histo-morphometrical features in association with the health and immune response of Grey Mullet (Liza ramada). Chitosan nanoparticles are included in the diets at 0, 0.5, 1, and 2 g/kg and introduced to fish in a successive feeding trial for eight weeks. The final body weight (FBW), weight gain (WG), and specific growth rate (SGR) parameters are significantly increased while feed conversion ratio (FCR) decreases by chitosan nanoparticles compared to the control (p < 0.05). The morphometric analysis of the intestines reveals a significant improvement in villus height, villus width, and the number of goblet cells in chitosan-treated groups in a dose-dependent manner. Additionally, there is a positive correlation between the thickness of the enterocyte brush border and the chitosan dose, referring to an increasing absorptive activity. Histologically, the intestinal wall of Grey Mullet consists of four layers; mucosa, sub-mucosa, tunica muscularis (muscular layers), and serosa. The histological examination of the L. ramada intestine shows a normal histo-morphology. The epithelial layer of intestinal mucosa is thrown into elongated finger-like projections, the intestinal villi. The values of hemoglobin, hematocrit, red blood cells (RBCs), total protein (TP), albumin, and globulin are significantly increased in fish fed 1, and 2 g/kg of chitosan nanoparticles compared to fish fed 0 and 0.5 g/kg (p < 0.05). The highest levels of TP and albumin are observed in fish fed 1 g/kg diet (p < 0.05). The lysozyme activity and phagocytic index are significantly enhanced by feeding chitosan nanoparticles at 0.5, 1, and 2 g/kg, whereas the phagocytic activity is improved in fish fed 1 and 2 g/kg (p < 0.05). The highest lysozyme activity and phagocytic index are observed in fish fed 1 g/kg. SOD is significantly activated by feeding chitosan nanoparticles at 1 g/kg. Simultaneously, glutathione peroxidase (GPx) and catalase (CAT) activities also are enhanced by feeding chitosan at 1 and 2 g/kg, compared to fish fed 0 and 0.5 g/kg (p < 0.05). The highest GPx and CAT activities are observed in fish fed 1 g/kg (p < 0.05). Conversely, the malondialdehyde (MDA) levels are decreased by feeding chitosan at 1 and 2 g/kg, with the lowest being in fish fed 1 g/kg (p < 0.05). To summarize, the results elucidate that L. ramada fed dietary chitosan nanoparticles have a marked growth rate, immune response, and anti-oxidative response. These improvements are attributed to the potential role of chitosan nanoparticles in enhancing intestinal histo-morphometry and intestinal health. These results soundly support the possibility of using chitosan nanoparticles at 1–2 g/kg as a feasible functional supplement for aquatic animals.     

基于耦合协调度的大理河流域径流和输沙关系分析

深入研究流域水沙关系变化是解决黄河流域高质量发展关键问题的重要科学途径之一。自20世纪50年代以来,黄河中游地区实施了大规模的水土保持工程,径流和输沙显著减少,水沙关系发生变化。该研究利用Mann-Kendall趋势检验法分析了1960—2015年来大理河流域的径流输沙变化趋势,并构建基于耦合协调度理论和Pettitt检验方法的径流输沙关系变异诊断方法,识别大理河流域径流和输沙关系的突变点,并通过Copula方法进行验证。结果表明:1)大理河流域径流输沙在月尺度和年尺度呈现显著的下降趋势;2)大理河流域径流和输沙关系在1996年发生显著突变;3)径流输沙关系发生突变后,径流和输沙均明显减少,输沙的减少幅度比径流的减少幅度高29.19个百分点,径流对输沙贡献程度下降幅度为5.10%,单位径流的输沙能力降低;4)淤地坝建设和植被恢复是造成大理河流域水沙变化的主要因素,修建淤地坝和恢复植被对减少泥沙具有积极作用。研究成果可以为进一步深化理解大理河流域水沙关系变化以及水土流失治理提供依据。     

天津市产业碳排放的影响因素及贡献

[目的] 综合考虑“水—土—能—碳”相互关系，研究产业碳排放的影响因素及贡献，为天津市减排决策制定提供一定依据。[方法] 对天津市产业碳排放进行测算，将水土资源因素引入Kaya恒等式，运用LMDI模型计算产业碳排放各影响因素的贡献。[结果] 2004—2018年天津市各产业碳排放均呈现上升趋势；整体来看，水资源经济产出、人口数量促进天津市各产业碳排放，且前者为主要促进因素，水土资源因素抑制各产业碳排放，碳排放强度促进农业碳排放，而抑制其他产业碳排放，人均用地面积抑制农业碳排放，而促进其他产业碳排放；水土资源因素对各产业碳排放影响的变化与水土资源匹配度变化有较好的一致性，单位用地面积用水量越多，其对碳排放的促进作用越大。[结论] 为实现节能减排，应发展节水产业，优化城市水土资源开发利用，发挥水土资源因素对碳排放的抑制作用。     

黑土区田块尺度下地形影响作物长势机理分析

为揭示作物长势及水肥运移的空间分异规律,探究田块尺度内作物长势与地形变化的关系,以东北典型黑土区东兴农机合作社为研究区,沿南北垄向提取高精度数字高程模型(Digital elevation model,DEM)与归一化植被指数(Normalized differential vegetation index,NDVI)信息,构建地形指标,分析NDVI的空间变异性。结果表明,坡型凸凹程度越明显,NDVI的空间变异性越大;同类坡型中阴坡NDVI的空间变异性与坡型凸凹程度呈负相关;坡度在±0.03范围内,作物长势好,空间变异性低;以坡度绝对值高于0.04的坡度均值与其对应直线距离所占整条直线的比值作为自变量,构建多元逐步回归模型,进行回归分析,可以解释大豆NDVI决定系数为0.965 2、高粱NDVI决定系数为0.888 3的空间变异性。不同地理空间的地形与成土母质差异显著,通过分析研究区内地形对作物长势的影响规律,可为田块尺度地形的分析提供借鉴,有助于指导农户合理地进行水肥分配。     

重庆市主要农产品供给能力分析

根据《重庆统计年鉴》数据,选取粮食、蔬菜、油料、猪肉和水产品等5个指标,利用相关农业、经济社会统计数据和盈余度计算方法,对重庆市主要农产品供给能力进行分析。结果表明:2003~2012年,重庆市粮食、蔬菜和猪肉产品的供给能力处于稳定的状态,水产品的供给能力有一定程度的下降,油料产品缺口不断扩大;5大功能区之间的盈余情况在结构和空间布局上都存在较大差异。为保障农产品供给,需要继续加大力度支持农业生产。     

黄淮海旱作区土壤压实度空间分布特征及其影响因素

为探究旱作区农田不同层次土壤压实度特征,基于2017年采集的255个土壤样品,运用Mann-Kendall突变检验法、地统计学和冗余分析等方法,探究黄淮海旱作区耕作层和压实层空间分布特征,分析不同层次的土壤压实度的空间变异特性及影响因素,并提出了最佳土壤压实度范围。研究结果表明:旱作区耕作层和压实层厚度均呈现由北向南递增的趋势,耕作层最大厚度可达22.50 cm,最低仅有10.21 cm;压实层厚度最大可达17.50 cm,最小值也达到7.50 cm。从不同层次来看,耕作层和压实层的压实度具有空间分布一致性,耕作层压实度高值区主要分布在河南省东部、安徽北部及河北北部地区,最大值可达87.68%以上,低值区则主要集中在山东西北部以及河北南部地区。和压实层压实度相比,耕作层压实度是影响粮食产量的主要因素,且在70%～80%时获得较高产量。分析表明,土壤压实度受到年降水量、平均气温、土壤自然属性等环境因子和机械耕作等人为因素综合作用的影响。研究结果可为黄淮海农田土壤压实情况的改善及管理措施的科学制定提供理论支撑。     

天气衍生品的运作机制与精算定价

天气衍生品是为了规避天气风险给天气敏感行业带来收入的不稳定性而兴起的创新型风险管理工具，其实质是通过衍生合约对天气风险进行分割、重组和交易的证券化产品。不同于传统金融衍生品，天气衍生品的价值取决于温度、湿度或降雨量等天气指数。本文在分析天气衍生品市场发展的基础上，重点探讨了最常见的天气期货和天气期权的运作机制及其精算定价。     

祁连山南麓高寒灌丛GPP变化特征及对生长季积温的响应

全球气候变化背景下气温逐渐升高,将会对陆地生态系统碳循环产生重要影响。研究利用2003?2016年的涡度相关系统观测资料,研究了祁连山南麓高寒灌丛生长季(5月?9月)总初级生产力(gross primary productivity,GPP)在不同时间尺度上对生长季有效积温(growing season degree days,GDD)的响应,对于研究气候变暖对高寒生态系统碳循环的影响有重要意义。结果表明:高寒灌丛生态系统在生长季的月GPP、GDD都表现为先增大后减小的单峰变化趋势,都在7月或8月达到峰值,在5月达到最小值。在整个生长季尺度上,GPP与GDD具有较高变异性,但整体上表现为逐渐增加的趋势(P<0.05)。2003?2016年整个生长季GPP与GDD的均值分别为507.11 g·m^?2和975.93℃。在月尺度和生长季尺度上,GPP与GDD都呈显著正相关关系(P<0.05)。但是,通过比较生长季每个月GPP与GDD的关系发现,5、9月的GPP与GDD没有显著相关性(P>0.05),而在7月相关性最为显著(P<0.01)。整体上看,高寒灌丛生态系统植被的总初级生产力与热量条件表现为正相关关系,由此说明在全球气候变暖的背景下,青藏高原高寒灌丛生态系统植被的光合生产能力将会提高。     

甘肃陇西黄芩灰霉病病原菌分离鉴定及田间药剂防治

为探明黄芩(Scutellaria baicalensis Georgi)茎基部和根部灰霉病的病原菌,本文于2019—2021年春季对甘肃陇西县采集的黄芩病样进行病原菌的分离培养,运用形态学和内转录间隔区(Internal transcribed spacer, ITS)、甘油醛-3-磷酸脱氢酶(Glyceraldehyde-3-phosphate dehydrogenase,G3PDH)、热激蛋白60(Heat shock protein 60,HSP60)和RNA聚合酶亚基II(The second largest subunit of the nuclear RNA polymerase enzyme II,RPB2)多基因方法鉴定,采用菌丝生长抑制法进行药剂室内毒力测定和田间药剂防治试验。结果表明：引起黄芩灰霉病的病原菌为灰葡萄孢(Botrytis cinerea),春季发病时表现为地上部分枯死不发芽,靠近地表的根表面呈暗绿色水渍状,随后地下根木质部变软呈黄褐色腐烂,病健交界明显;室内毒力测定表明,97%咯菌腈对灰葡萄孢菌的抑菌作用最强,EC₅₀为0.01...