低覆盖度行带式固沙林对土壤及植被的修复效应

在我国干旱、半干旱地区由于水分条件的制约,经过漫长的自然演替过程,逐步发育形成了广泛分布的低覆盖度植被,这些低覆盖度植被类型中存在大量的天然乔木疏林或稀疏灌丛,地表处于半流动状态,而配置成行带式后,能够完全固定流沙,并且不同配置模式下行带式固沙林土壤与植被自然恢复程度不同.因此,通过对不同带宽的低覆盖度行带式固沙林对土壤及植被修复的影响研究,揭示了不同带宽行带式固沙林带间土壤因子与植被因子的变化过程,从而阐明行带式固沙林对带间植被自然恢复和土壤发育的促进作用.结果表明,行带式杨树固沙林能够明显的促进带间土壤与植被修复;带间距离的宽窄影响植被恢复及土壤发育效果;宽带间距固沙林带间植被多样性指数高,地上生物量大,根系生物量,总长度及表面积均高,土壤水分养分条件好,微生物数量大植物残体分解快,有利于植被的生长;模糊综合评估结果表明,不同带间距行带式固沙林土壤植被恢复程度不同,宽带间距20m的恢复效果＞带间距15m＞带间距10m.行带式固沙林通过带间宽度的变化可以调节植被与土壤之间的相互作用,窄带间距固沙林土壤与植被的相互作用则由于造林密度大而受到抑制.宽带间距可以明显加快土壤及植被修复的速度,进而缩短土壤及植被修复的时间.     

Study on separation algorithm of convolutive mixing model and separation of mixing signals of multiple partial discharges

To identify individual partial discharges(PD)signals produced by multiple insulation defects in gas insolated switchgear (GIS),this paper analyses the mechanism of propagation and mixing of multiple PD electromagnetic wave signals in GIS cylinder and proposes the convolutive mixing model to describe it for a separation algorithm to acquire individual PD signals. With the non-stationary property,mixing PD signals are changed at time domain into a set consisting of short-time stationary PD signals and then the Molgedey-Schuster decorrelation approach is employed to separate these stationary PD signals at frequency domain. The correlation of the envelope of separated PD signals in this set is used to reconstruct PD signals to realize the separation of non-stationary UHF PD mixtures. The effective separation of actual UHF PD mixing signals validates the assumption of convolutive mixing process in GIS and also offers a new approach to the identification of mixing PD signals by external ultra-high frequency detection scheme from multiple insulation defects in GIS.     

光照、温度和沙藏对草珊瑚种子萌发的影响

在三明市三元区研究草珊瑚种子发芽率和发芽指数与光照、温度和沙藏时间的关系.结果表明,光照、温度和沙藏时间对草珊瑚种子的发芽率和发芽指数影响极显著,最高发芽率是最低的3.10倍,最高发芽指数是最低的8.63倍.有光照的草珊瑚发芽率显著高于无光照的发芽率;随着温度的增加,草珊瑚种子发芽率表现出先升后降的趋势,25℃时种子发芽率和发芽指数最高;沙藏时间对种子发芽率和发芽指数影响最大,沙藏90 d的种子发芽率在90.00％以上.影响草珊瑚种子发芽率的各因素作用大小依次为沙藏时间＞光照＞沙藏时间×光照＞温度＞沙藏时间×温度,影响发芽指数的各因素作用大小依次为沙藏时间＞光照＞温度＞沙藏时间×温度＞沙藏时间×光照.因此,草珊瑚种子宜分批采种、晾干后即沙藏,3月底到4月间播种,播种时宜浅播.     

Amending a loamy sand with three compost types: impact on soil quality

The objective of this study was to investigate the effects of the long‐term addition of three compost types (vegetable, fruit and yard waste compost – VFYW, garden waste compost – GW and spent mushroom compost – SM) on the physical properties of a sandy soil and to quantify any such effects using indicators of soil physical quality. Soil samples were taken from a field with annual compost applications of 30 m³/ha for 10 yr and various physico‐chemical analyses were undertaken. Results show a significant increase in soil organic carbon (21%) with the VFYW and GW compost types. With SM, soil organic carbon increased by 16%. Increased soil macroporosity and water content at saturation with a corresponding decrease in bulk density were observed for all compost types. However, quantification of these improvements using existing soil physical quality indicators such as the ‘S‐index’, soil air capacity and matrix porosity gave mixed results showing that these indices perform poorly when applied to sandy soils. It is concluded that the long‐term application of compost does not significantly improve the physical properties of sandy soils, but the absence of adverse effects suggests that these soils are a viable disposal option for these composts, but new indices of quality are needed for the proper characterization of sandy soils.     

外植体取样时间对沙子空心李诱导培养的影响

【目的】研究取样时间对沙子空心李诱导培养的影响,为沙子空心李组织培养技术提供理论依据。【方法】以不同时间段的沙子空心李半木质化茎段为外植体,经过2种消毒方式后进行诱导培养。【结果】结果表明,使用0.1%HgCl₂进行消毒时,污染率最低,随着外植体取样时间的推移,诱导死亡率逐渐降低,4月25日取外植体时,死亡率与死亡率最低,成活率最高,分别为4%、10%和86%,与2%NaClO消毒效果无明显差异,但其余3次取样时,2种消毒剂的消毒效果差异明显,且0.1%HgCl₂明显优于2%NaClO。【结论】沙子空心李的适宜消毒方式是D2：75%酒精消毒10 s+0.1%HgCl₂消毒5min；诱导组培的外植体适宜取样时间是4月下旬。     

不同改良方法对盐碱土壤水盐运移效果的影响

以取自山东省东营市的中度盐碱土为研究对象，为探究表层（0~20 cm）掺沙和掺生物炭处理对黄河三角洲地区盐碱土的改良效果，在室内进行了垂直一维积水入渗试验，分别研究两种方法对土壤水分入渗、土壤剖面含水率和含盐量的影响。试验土壤为中度盐碱土(含盐量2.381 g·kg^-1)，试验共设置7个处理，分别是：CK(掺沙或生物炭0%)、S1(掺沙5%)、S2(掺沙10%)、S3(掺沙20%)、C1(掺生物炭0.5%)、C2(掺生物炭1%)、C3(掺生物炭2%)。结果表明：在相同入渗情况下，表层（0~20 cm）掺沙、生物炭均能提高盐渍化土壤中水分入渗效果，掺加生物炭显著提高添加层的蓄水能力，掺沙显著提高掺沙层以下土壤含水率，在土层20~40 cm中，掺沙处理平均土壤含水率比掺生物炭处理提高1.37%；不同改良剂处理下，掺沙更有利于盐碱化土壤脱盐，20%掺沙处理平均脱盐率比掺生物炭处理提高5.26%~13.80%，脱盐区深度增加2.35%~3.92%，达标脱盐区深度增加1.70%~3.00%。根据河沙和生物炭在室内一维垂直积水入渗试验结果来看，土壤表层掺沙能有效解决黄河三角洲地区盐碱化土壤问题，改善土壤水盐分布，为作物生长提供良好的生长环境。     

Effects of temperature and light on seed germination of ephemeral plants in the Gurbantunggut Desert,China: implications for vegetation restoration

Seed germination is a key transitional stage in plant life cycle and is strongly regulated by temperature and light. Therefore, research on the effects of temperature and light on seed germination is extremely meaningful for vegetation restoration, especially in desert ecosystems. Seeds of 28 ephemeral plants collected from the Gurbantunggut Desert of China were incubated at different temperatures (5°C/1°C, 15°C/5°C, 20°C/5°C, 25°C/10°C and 30°C/15°C) in 12-h light/12-h darkness or continuous darkness regimes, and the responses of seed germination to temperature and light and the germination speed were studied in 2016. Results showed that seed germination percentage of the 28 ephemeral plants significantly differed to temperature and light. We classified the studied plants as the following groups based on their responses to temperature: 1 low temperature responsed plants, 12 moderate temperature responsed plants, 7 high temperature responsed plants, 4 non-responsed plants and 5 plants of no germination. It should be noted that Corispermum lehmannianum Bunge is sensitive to both moderate and high temperatures. There were 4 groups of plant in response to light, i.e., 7 light responsed plants, 10 dark responsed plants, 6 light non-responsed plants and 5 plants of no germination. Based on seed germination speed of the 28 ephemeral plants, we divided them into 4 patterns of germination, i.e., very rapid, moderately rapid, moderate and slow. Combining variations of temperature, precipitation and sand dune types in the study area, we suggested that very rapid and moderately rapid germinated plants could be used to moving sand dunes in early spring during vegetation restoration, moderate germinated plants could be used to semi-fixed sand dunes in late autumn, and slow germinated plants could be used to sand plain in summer. Thus, seedling establishment and vegetation restoration would be improved by considering seed germination characteristics of these ephemeral plants in the Gurbantunggut Desert, China.     

设施蔬菜固液混合水肥管理系统建设实践及思考

针对北京市设施蔬菜生产园区对水肥管理装备技术的需求,引进建设了固液混合水肥管理系统,实现了水肥管理调控的自动化、数据化和精准化,提高了园区劳动生产效率,实际应用中每年每667 m2设施蔬菜可提高经济效益2066元。并结合系统建设实践,从水源设计、防冻设计和系统维修维护服务等建设要点方面提供了建议。     

Stable oxygen-hydrogen isotopes reveal water use strategies of Tamarix taklamakanensis in the Taklimakan Desert,China

Tamarix taklamakanensis,a dominant species in the Taklimakan Desert of China,plays a crucial role in stabilizing sand dunes and maintaining regional ecosystem stability.This study aimed to determine the water use strategies of T.taklamakanensis in the Taklimakan Desert under a falling groundwater depth.Four typical T.taklamakanensis nabkha habitats(sandy desert of Tazhong site,saline desert-alluvial plain of Qiemo site,desert-oasis ecotone of Qira site and desert-oasis ecotone of Aral site)were selected with different climate,soil,groundwater and plant cover conditions.Stable isotope values of hydrogen and oxygen were measured for plant xylem water,soil water(soil depths within 0–500 cm),snowmelt water and groundwater in the different habitats.Four potential water sources for T.taklamakanensis,defined as shallow,middle and deep soil water,as well as groundwater,were investigated using a Bayesian isotope mixing model.It was found that groundwater in the Taklimakan Desert was not completely recharged by precipitation,but through the river runoff from snowmelt water in the nearby mountain ranges.The surface soil water content was quickly depleted by strong evaporation,groundwater depth was relatively shallow and the height of T.taklamakanensis nabkha was relatively low,thus T.taklamakanensis primarily utilized the middle(23%±1%)and deep(31%±5%)soil water and groundwater(36%±2%)within the sandy desert habitat.T.taklamakanensis mainly used the deep soil water(55%±4%)and a small amount of groundwater(25%±2%)within the saline desert-alluvial plain habitat,where the soil water content was relatively high and the groundwater depth was shallow.In contrast,within the desert-oasis ecotone in the Qira and Aral sites,T.taklamakanensis primarily utilized the deep soil water(35%±1%and 38%±2%,respectively)and may also use groundwater because the height of T.taklamakanensis nabkha was relatively high in these habitats and the soil water content was relatively low,which is associated with the reduced groundwater depth due to excessive water resource exploitation and utilization by surrounding cities.Consequently,T.taklamakanensis showed distinct water use strategies among the different habitats and primarily depended on the relatively stable water sources(deep soil water and groundwater),reflecting its adaptations to the different habitats in the arid desert environment.These findings improve our understanding on determining the water sources and water use strategies of T.taklamakanensis in the Taklimakan Desert.     

植物固沙技术研究进展及展望

介绍了3种固沙措施的防风治沙机理,梳理了植物固沙的研究现状,并简要阐述了其主要成就及存在的问题,以期为未来固沙植物的选择和布设方案提供新思路。