Assessment of early survival and growth of planted Scots pine(Pinus sylvestris) seedlings under extreme continental climate conditions of northern Mongolia

Environmental factors play vital roles in successful plantation and cultivation of tree seedlings.This study focuses on problems associated with reforestation under extreme continental climatic conditions.The objectives were to assess relative seedling performance(survival and growth)with respect to plantation age,and to analyze the influence of specific climatic factors during the early stages of Scots pine(Pinus sylvestris L.)plantations.The study was carried out in reforested areas of the Tujyin Nars region of northern Mongolia on six Scots pine plantations ranging from 5 to 10 years.In each of the six plantations,five 900 m^2 permanent sample plots were established and survival rates and growth performance measured annually over 7 years.Results show high variation in survival among the plantations(p<0.001,F=29.7).Seedling survival in the first year corresponded directly to the number of dry days in May.However,survival rate appeared to stabilize after the second year.The insignificant variation of height categories throughout the observation period indicated low competition among individuals.Two linear mixed-effect models show that height and radial growth were best explained by relative air humidity,which we consider to be a reliable indicator of site-specific water availability.Insufficient amounts and uneven distribution of rainfall pose a major threat during the first year of plantation establishment.Humidity and water availability are decisive factors for a successful seedling plantation.This highlights the impact of drought on forest plantations in northern Mongolia and the importance of developing climate resilient reforestation strategies.     

布氏田鼠栖息地特征的研究

依据2008-2010年在中蒙2国的实地调查,研究了布氏田鼠(Lasiopodomys brandtii)对栖息地的选择特点,以期为该鼠的综合防治提供依据。选择316个样点,记录每个样点的布氏田鼠密度,并随机调查5～10个1m×1m的样方,记录海拔、植被盖度、植被高度、枯草盖度、植被优势种、郁闭指数和退化级别。利用相关性分析及因子分析选取布氏田鼠栖息地选择影响较大的因子。结果表明:布氏田鼠密度与植被盖度、枯草盖度、退化等级及郁闭指数相关;冷蒿(Artemisia frigida)、羊草(Leymus chinensis)和多根葱(Allium polyrhizum)3种植物多度、枯草盖度、植被盖度、草场退化程度和植被郁闭指数5个因子对该鼠选择栖息地影响显著,即布氏田鼠倾向于选择以冷蒿、羊草、多根葱为优势种,放牧利用程度高、植被低矮的退化草场。     

基于机器学习识别中微量元素与我国七大片区产地稻米镉、砷的富集规律

本研究在全国大尺度空间范围内,基于机器学习识别稻米镉（Cd）、砷（As）富集的重要影响因素,探究了中微量元素对稻米Cd、As超标的贡献率并构造了生物有效性模型。首先,通过决策树算法构造中微量元素判别Cd、As超标的预测模型,其预测精度分别为95.55%、97.55%,表明中微量元素是识别稻米Cd、As超标的重要指标;其次,利用随机森林算法筛选影响稻米Cd、As富集的主控因子,不同区域的主控因子表现出明显差异,其单一因子主要驱动的Cd富集在不同区域的差异表现为：华东片区pH的贡献占主导、华南片区的交换性钙（Ca）和东北片区的土壤有机质（SOM）分别占主要贡献,而有效铁（Fe）对As富集表现出特异性的区域贡献（如华东、华南和西南片区）;最后,将各区域确定的主控因子引入构建土壤-稻米生物有效性模型,其中,Cd、As的生物有效性九因子模型在不同片区的决定系数最高,分别为0.680、0.664 （P<0.05）。本研究为大尺度地域水平上稻米Cd、As重金属污染防控和环境管理提供了科学依据和决策支撑。     

Thunderstorms have species and gear-specific indirect effects on the catchability of Mongolian salmonids

Climate change is predicted to cause increasingly frequent and intense storms. Northern Mongolia is already warming at a rate twice the global average, and thunderstorms, defined as intense, short, patchy rains associated with thunder, lightning and high precipitation rates, are becoming more frequent. Because Mongolia's fish populations are lightly exploited, Mongolia provides a model system in which to study the effects of storms on fish behaviour and fishing vulnerability. The impacts of thunderstorm-related hydrological changes on fishes’ vulnerability to two fishing gears were evaluated. Two thunderstorm-related factors, turbidity and river stage, reduced catch rates of the salmonids lenok Brachymystax lenok (Pallas) and Baikal grayling Thymallus baicalensis Dybowski. Fly-fishing gear was more effective than spinning gear in this fishery and retained higher catch rates in extreme conditions. These gear-specific effects suggest that turbidity and rising river stage affect fishing vulnerability by influencing feeding behaviour.     

内蒙古自治区绵羊生产成本影响因素的计量分析

[目的]分析内蒙古自治区绵羊生产成本影响因素。[方法]利用2001—2019年《全国农产品成本收益资料汇编》中内蒙古自治区的绵羊生产成本相关数据,对该地区绵羊生产成本进行计量分析;采用EViews 7.0软件建立回归分析模型,以精饲料和饲盐费、饲草费、医疗防疫费、配种费、死亡损失费、放牧用具费、修理维护费和间接费用等8项指标作为解释变量,分析不同生产要素对绵羊生产成本的影响。[结果]在5%显著性水平下,绵羊饲养管理中的精饲料和饲盐费、饲草费、医疗防疫费、配种费、死亡损失费对绵羊生产成本有显著（5%）影响。[结论]精饲料和饲盐费、饲草费、医疗防疫费、配种费、死亡损失费的增加是绵羊生产成本增加及收益减少的主要影响因素。