胡杨实生苗在河漫滩自然发生和初期生长的研究

通过对洪水退后河漫滩上胡杨种子散布，种子萌发以及胡杨幼苗生长的观察，认定胡杨种子萌发和幼苗初期生长需要一个高温、高湿的环境。水分、温度、光照和微地形对胡杨幼苗的生长和保存都有很大的影响，其中，水分是最为重要的一个因素。洪水退后的河漫滩应是胡杨种子自然萌发和幼苗自然补充的最佳场所，洪水则是胡杨种子自然萌发以及幼苗补充的一个必要条件。     

胡杨资源信息管理系统的设计与实现

新疆塔里木河流域的胡杨资源在维持荒漠生态系统的协调稳定和保障绿洲生态安全等方面意义重大。运用GIS技术、多媒体技术、数据库管理技术的理论与方法,综合胡杨资源及其环境的遥感信息、文字信息及地图信息,建立集图象、图形、声音、文字为一体的计算机信息管理系统,为胡杨资源信息的存贮、查询、检索、更新、分析服务,同时,为胡杨资源合理利用及保护提供科学依据及决策支持。     

黄肉猕猴桃新品种“金实1号”果实生长规律研究

"金实1号"猕猴桃是从野生猕猴桃实生后代中选育出来的黄肉猕猴桃新品种。为了研究其果实生长发育特性,在盛花期后16—176天对果实纵横径、单果重、干物质含量、可溶性糖、硬度、果肉颜色等指标进行了测定与统计分析。结果表明:"金实1号"猕猴桃果实呈单"S"曲线生长,分为细胞分裂期(盛花期后50天)、果实膨大期(盛花期后50—135天)和果实成熟期(盛花期后135—150天) 3个阶段。单果重和果实纵横径表现出快速增长—缓慢增长—停滞增长的变化规律;盛花期58天之后,干物质含量快速积累,果实成熟后增长缓慢;可溶性糖含量在盛花期后135天才开始快速增加;果实硬度和果肉颜色在整个生长发育期一直呈递减趋势,盛花期后135天,果实硬度下降趋势变缓,果肉颜色下降趋势加快。     

春来荠菜香

荠菜,又名枕头草、粽子菜、菱角菜、地菜.十字花科植物,叶片呈缺刻或锯齿状,叶表面略灰白毛茸,根系发达、较深,伏地而生,多生长在田埂山野.根鲜具有特殊清香儿,味道清香鲜美.<诗经>唱道:"谁谓荼苦,其甘如荠."说的就是荠菜.     

中国北方全新世降水分区对比分析

不同区域由于影响降水因素的不同而表现出不同的全新世降水变化特征,利用中国北方全新世9个古降水数据,分析全新世不同区域的降水特征,可以很好地理解11.5ka BP以来降水的空间变化特征、气候驱动机制及其耦合关系。通过对中国北方不同区域全新世降水特征的对比分析发现,全新世北方变化特征是早全新世降水偏少,中全新世气候湿润,晚全新世干旱。早全新世西部地区干旱程度比北方东部季风区更强,可能是由于全新世早期北大西洋水汽输送减少,西风减弱,局地温度高蒸发量大造成的;北方东部季风区与西部之间降水存在一定差异,但黄土高原与西北干旱区的降水变化特征具有较好的一致性;季风区的降水波动幅度大于其他区,湿润期的起始时间早于西北内陆地区,且东亚季风边缘区的湿润期要晚于其他地区,持续时间也较短。     

1960~2019年静海高温天气变化特征分析及日高温概率模型

利用静海国家气象站1960~2019年日最高气温资料对静海高温天气发生的开始和结束时间、次数进行了统计,分析了持续高温天气过程的年际变化规律、时间演变特征,利用Mann-Kendall法对高温日数、年最高气温进行趋势检验;构建了日高温发生概率的“钟形”曲线模型,利用傅里叶变换分析日高温发生概率序列的主要分量,构建了基于傅里叶级数的日高温发生概率简化模型。结果表明:1960年至1996年静海年高温日数呈下降趋势,1997年开始年高温日数呈上升趋势,而年最高气温无显著的上升趋势;静海高温天气过程主要为持续1~2天的过程,近20年高温热浪发生次数明显增加;近60年高温日开始时间提前,结束时间推迟的趋势明显;模型较好的模拟了日高温发生概率的变化特征。     

紫苏水浸液对木香薷种子萌发和幼苗生长的化感作用CSSCI

以紫苏茎、叶、花序为供体,木香薷种子为受体,采用3×5二因素完全随机试验设计和室内生物测定法研究了紫苏水浸液对木香薷种子萌发及幼苗生长的化感作用。结果表明:1供体类型和水浸液浓度对木香薷种子的发芽势、发芽指数、发芽率、成苗率、胚根长度和胚轴长度均有极显著影响。供体化感作用强弱顺序是:叶片>花序>茎,并有高抑制低促进的浓度效应。2紫苏茎、叶、花序的水浸液主要是通过抑制木香薷胚根的伸长来抑制种子萌发与幼苗生长。3叶片淋溶是紫苏释放化感物质的主要途径之一。     

本期导读

正从"督企"到"督政"再到"党政同责""一岗双责",中国历史上最严格的环境治理层层递进、不断深化。日前,第一批中央环保督察为期一个月的现场督察阶段基本结束,在这个不长的时间里,被督察的8个省区均经历了治污问责的洗礼:百余人因破坏生态和污染环境被刑事拘留,罚款额或可过亿;一些党政部门的2千余人被问责,多数被给予了党纪政纪处分。这一组数字     

来自松水边的“胡杨”——记我省环保系统技术援疆干部杨旭海

2011年8月,在全国环保系统技术援藏援疆工作启动会上,一位援疆干部代表全体援疆干部庄严表态",一定会克服困难,圆满完成此次援疆工作。"这位援疆干部就是吉林省环境监察总队副调研员杨旭海。     

衡水市空气主要污染物体积质量的时间分布特征

利用衡水市环境监测站2005—2007年度大气例行检测的数据，对衡水市大气中主要污染物SO^2、NO^2、PM10体积质量值的逐日数据进行统计分析，得出了衡水市空气污染的现状和时间变化规律：（1）污染物体积质量值的月变化曲线呈槽型分布，非取暖期的空气状况明显好于取暖期，取暖期SO^2平均体积质量是非取暖期的2．45倍；（2）污染物体积质量值的日变化曲线基本为两高两低型，其中取暖期污染指数早晨出现极高值的时间比非取暖期明显偏晚；（3）污染物体积质量值的年变化表明了SO^2的体积质量在降低，而NO^2的体积质量却有了小幅增长。     

浅析叶尔羌河流域胡杨林的演变规律及生态保护对策

胡杨是一个古老的第三纪孑遗树种,胡杨林生态系统在绿洲演替与发展的不同阶段发挥着主要作用.通过对叶尔羌河流域胡杨林的生存现状、演变规律的调查,总结和分析当前胡杨林存在的一些生态环境问题,结合其流域特征和流域总体规划,对叶尔羌河流域开发中胡杨林的保护对策进行探讨.     

杨树伐根嫁接毛白杨试验初报

应用青杨、新疆杨伐根嫁接毛白杨，当年苗最高可达4．1m，地径5cm，生长优于一般造林和地膜扦插、埋条育苗。利用该技术为今后青杨的更新改造，调整树种结构，防御病虫害（尤其是黄斑星天牛虫害），引进优良树种以及伐根资源的有效利用开辟了一条新途径。     

胡杨林的衰退原因与林地恢复策略

胡杨广布于地中海沿岸并呈带状东延至中国和蒙古人民共和国。目前,胡杨林已普遍呈不同程度退化,以塔里木盆地为例,垦伐等人为因素使林地总面积迅速减少。现场观测发现,一些林区缺乏胸径20cm以下的立木,而该地从1972年以来断绝洪水来源,显示洪水对幼苗补给可能存在相关,该地断绝洪水多年后,2002年重新出现洪泛过程,洪水退后出现大量的幼苗生长,从而证实洪水过程是胡杨幼林发生的必要条件。本文就此现象提出恢复部分林地的对策。     

Physiological and morphological response patterns of Populus deltoides to alluvial groundwater pumping

We examined the physiological and morphological response patterns of plains cottonwood [ Populus deltoides subsp. monilifera (Aiton) Eck.] to acute water stress imposed by groundwater pumping. Between 3 and 27 July 1996, four large pumps were used to withdraw alluvial groundwater from a cottonwood forest along the South Platte River, near Denver, Colorado, USA. The study was designed as a stand-level, split-plot experiment with factorial treatments including two soil types (a gravel soil and a loam topsoil over gravel), two water table drawdown depths ( approximately 0.5 m and >1.0 m), and one water table control (no drawdown) per soil type. Measurements of water table depth, soil water potential (Psi(s)), predawn and midday shoot water potential (Psi(pd) and Psi(md)), and D/H (deuterium/hydrogen) ratios of different water sources were made in each of six 600-m(2) plots prior to, during, and immediately following pumping. Two additional plots were established and measured to examine the extent to which surface irrigation could be used to mitigate the effects of deep drawdown on P. deltoides for each soil type. Recovery of tree water status following pumping was evaluated by measuring stomatal conductance ( g(s)) and xylem water potential (Psi(xp)) on approximately hourly time steps from before dawn to mid-afternoon on 11 August 1996 in watered and unwatered, deep-drawdown plots on gravel soils. P. deltoides responded to abrupt alluvial water table decline with decreased shoot water potential followed by leaf mortality. Psi(pd) and percent leaf loss were significantly related to the magnitude of water table declines. The onset and course of these responses were influenced by short-term variability in surface and ground water levels, acting in concert with physiological and morphological adjustments. Decreases in Psi(pd) corresponded with increases in Psi(md), suggesting shoot water status improved in response to stomatal closure and crown dieback. Crown dieback caused by xylem cavitation likely occurred when Psi(pd) reached -0.4 to -0.8 MPa. The application of surface irrigation allowed trees to maintain favorable water status with little or no apparent cavitation, even in deep-drawdown plots. Two weeks after the partial canopy dieback and cessation of pumping, g(s) and Psi(xp) measurements indicated that water stress persisted in unwatered P. deltoides in deep-drawdown plots.     

干旱区荒漠植被的特点及恢复问题的研究--以塔里木河流域胡杨林生态系统为例

干旱区除存在唯一的真正森林-胡杨(Populuseuphratica)林外,植被普遍极其稀疏,以降水稀少,蒸发显著为特点的干旱区,荒漠植被的存在对于生态环境的保护和良性发展起到极大的作用,干旱区的荒漠植被表现出特有的生理特征,本文研究塔里木河流域胡杨林的特征及对生态环境的适应规律,进一步提出了扩展荒漠植被的可能性及其措施。     

Physiological and Morphological Response Patterns of <Emphasis Type="Italic">Populus deltoides</Emphasis> to Alluvial Groundwater Pumping

We examined the physiological and morphological response patterns of plains cottonwood [Populus deltoides subsp. monilifera (Aiton) Eck.] to acute water stress imposed by groundwater pumping. Between 3 and 27 July 1996, four large pumps were used to withdraw alluvial groundwater from a cottonwood forest along the South Platte River, near Denver, Colorado, USA. The study was designed as a stand-level, split-plot experiment with factorial treatments including two soil types (a gravel soil and a loam topsoil over gravel), two water table drawdown depths (∼0.5 m and >1.0 m), and one water table control (no drawdown) per soil type. Measurements of water table depth, soil water potential (Ψ_s), predawn and midday shoot water potential (Ψ_pd and Ψ_md), and D/H (deuterium/hydrogen) ratios of different water sources were made in each of six 600-m² plots prior to, during, and immediately following pumping. Two additional plots were established and measured to examine the extent to which surface irrigation could be used to mitigate the effects of deep drawdown on P. deltoides for each soil type. Recovery of tree water status following pumping was evaluated by measuring stomatal conductance (g _s ) and xylem water potential (Ψ_xp) on approximately hourly time steps from before dawn to mid-afternoon on 11 August 1996 in watered and unwatered, deep-drawdown plots on gravel soils. P. deltoides responded to abrupt alluvial water table decline with decreased shoot water potential followed by leaf mortality. Ψ_pd and percent leaf loss were significantly related to the magnitude of water table declines. The onset and course of these responses were influenced by short-term variability in surface and ground water levels, acting in concert with physiological and morphological adjustments. Decreases in Ψ_pd corresponded with increases in Ψ_md, suggesting shoot water status improved in response to stomatal closure and crown dieback. Crown dieback caused by xylem cavitation likely occurred when Ψ_pd reached −0.4 to −0.8 MPa. The application of surface irrigation allowed trees to maintain favorable water status with little or no apparent cavitation, even in deep-drawdown plots. Two weeks after the partial canopy dieback and cessation of pumping, g _s and Ψ_xp measurements indicated that water stress persisted in unwatered P. deltoides in deep-drawdown plots.     

Dynamics of Plains Cottonwood (<Emphasis Type="Italic">Populus deltoides</Emphasis>) Forests and Historical Landscape Change along Unchannelized Segments of the Missouri River,USA

Construction of six large dams and reservoirs on the Missouri River over the last 50–75 years has resulted in major landscape changes and alterations in flow patterns, with implications for riparian forests dominated by plains cottonwood (Populus deltoides). We quantified changes in land cover from 1892–1950s and the 1950s–2006 and the current extent and age structure of cottonwood forests on seven segments (two reservoir and five remnant floodplain) comprising 1127 km (53 %) of the unchannelized upper two-thirds of the Missouri River. Riparian forest area declined by 49 %; grassland 61 %; shrubland 52 %; and sandbar habitat 96 %; while agricultural cropland increased six-fold and river/reservoir surface area doubled from 1892 to 2006. Net rates of erosion and accretion declined between the 1892–1950s and 1950s–2006 periods. Accretion exceeded erosion on remnant floodplain segments, resulting in declines in active channel width, particularly in 1950s–2006. Across all study segments in 2006, most cottonwood stands (67 %) were >50 years old, 22 % were 25–50 years old, and only 10 % were <25 years old. Among stands <50 years old, the higher proportion of 25–50 year old stands represents recruitment that accompanied initial post-dam channel narrowing; while declines in sandbar and shrubland area and the low proportion of stands <25 years old suggest declines in geomorphic dynamism and limited recruitment under recent river management. Future conservation and restoration efforts should focus both on limiting further loss of remnant cottonwood stands and developing approaches to restore river dynamics and cottonwood recruitment processes.     

Ecophysiological Competence of <Emphasis Type="Italic">Populus alba</Emphasis> L., <Emphasis Type="Italic">Fraxinus angustifolia</Emphasis> Vahl., and <Emphasis Type="Italic">Crataegus monogyna</Emphasis> Jacq. Used in Plantations for the Recovery of Riparian Vegetation

In many semi-arid environments of Mediterranean ecosystems, white poplar (Populus alba L.) is the dominant riparian tree and has been used to recover degraded areas, together with other native species, such as ash (Fraxinus angustifolia Vahl.) and hawthorn (Crataegus monogyna Jacq.). We addressed three main objectives: (1) to gain an improved understanding of some specific relationships between environmental parameters and leaf-level physiological factors in these riparian forest species, (2) to compare the leaf-level physiology of these riparian species to each other, and (3) to compare leaf-level responses within native riparian plots to adjacent restoration plots, in order to evaluate the competence of the plants used for the recovery of those degraded areas. We found significant differences in physiological performance between mature and young white poplars in the natural stand and among planted species. The net assimilation and transpiration rates, diameter, and height of white poplar plants were superior to those of ash and hawthorn. Ash and hawthorn showed higher water use efficiency than white poplar. White poplar also showed higher levels of stomatal conductance, behaving as a fast-growing, water-consuming species with a more active gas exchange and ecophysiological competence than the other species used for restoration purposes. In the restoration zones, the planted white poplars had higher rates of net assimilation and water use efficiency than the mature trees in the natural stand. We propose the use of white poplar for the rapid restoration of riparian vegetation in semi-arid Mediterranean environments. Ash and hawthorn can also play a role as accompanying species for the purpose of biodiversity.