岷江上游干旱河谷岷江柏木幼林地绿肥种植研究

在岷江上游干旱河谷岷江柏木幼林地经过连续4 a利用雨季种植绿肥压青,增加土壤肥力,提高水分利用率,促进幼树生长研究。结果表明:(1)种植红豆草的土壤0～40 cm含水量旱季增加3.68 g·kg-1,0～20 cm土壤容重降低0.07 g·cm-3;种植草木樨土壤0～40 cm含水量旱季增加4.18 g·kg-1,0～20 cm土壤容重降低0.05 g·cm-3;种植沙打旺土壤0～40 cm含水量增加2.46 g.kg-1,0～20 cm土壤容重降低0.18 g·cm-3。(2)种植绿肥压青,土壤有机质增加0.37 g·kg-1～0.55 g·kg-1,土壤CaCO3含量下降0.66 g·kg-1～1.36 g·kg-1,有效氮增加4.5 mg·kg-1～18.5 mg·kg-1,有效磷含量增加1.0～3.46 mg·kg-1,CEC比对照增加0.54～0.58mg.100g-1。(3)种植红豆草、草木樨、沙打旺绿肥压青对岷江柏木树高、地径生长有显著的促进作用,尤其种植红豆草的岷江柏木幼树生长最好,高、径生长为对照的1.7倍和1.6倍。     

岷江上游干旱河谷油松刺槐混交林研究

经过连续6a对岷江上游干旱河谷油松刺槐混交林分的土壤水分、养分、理化性质及林冠结构和效益研究,结果表明:(1)混交林土壤0~40 cm平均含水量比油松纯林增加0.91 g·kg-1、比刺槐纯林增加0.55 g·kg-1;(2)混交林18年后土壤容重比油松纯林减少0.13 g·cm-3、比刺槐纯林土壤容重减少0.10 g·cm-3;(3)混交林土壤有机质比纯林增加0.54 mg.kg-1~1.48 mg·kg-1、土壤碳酸钙含量比纯林减少0.43 mg·kg-1~1.09 mg.kg-1、土壤有效氮比纯林增加6.4 mg·kg-1~19.4 mg·kg-1、土壤有效磷比纯林增加0.36 mg·kg-1~1.37 mg·kg-1、土壤有效钾比纯林减少6.90 mg·kg-1~23.90 mg·kg-1,土壤CEC含量比纯林增加0.23 mg·100 g-1~0.85 mg·100 g-1;(4)混交林林冠面积、林冠厚度、林冠水分截留率分别比纯林提高47.83%~78.95%、40.63%~73.08%、6.15%~8.32%,枯落物饱和持水量是纯林的1.62倍~4.22倍;(5)混交林中油松的树高、胸径比纯林分别提高24.7%和27.35%,混交林年均利润是纯林的7.12倍。     

郑州市绿博园土壤肥力质量评价

采用野外调查与室内分析相结合的方式,对郑州市绿博园(枫湖区、展园区、湿地区、背景森林区、绿色生活体验区、休闲娱乐区6个功能区)土壤质量进行综合评价。结果表明,郑州市绿博园土壤,0~20 cm土层土壤容重、水解性氮、速效磷、速效钾、有机质和pH平均值分别为1.28 g·cm-3、28.45 mg·kg-1、3.41 mg·kg-1、162.23 mg·kg-1、8.22 g·kg-1、7.7;20~40 cm土层土壤容重、水解性氮、速效磷、速效钾、有机质和pH平均值分别为1.24 g·cm-3、21.26 mg·kg-1、2.07mg·kg-1、138.84 mg·kg-1、6.71 g·kg-1、7.5。0~20 cm土层土壤肥力除了休闲娱乐区处于较差水平外(P<1.0),其他功能区土壤肥力属于中等水平(1.0≤P<1.5);20~40 cm土层各个功能区土壤肥力均处于较差水平(P<1.0)。     

冀北辽河源地区不同林龄山杨天然次生林土壤理化特征的研究

为了探讨不同林龄山杨天然次生林土壤理化性质的差异,以辽河源地区山杨Populus davidiana为研究对象,研究了不同林龄的林分土壤理化特征及其垂直分布特征。结果表明:(1)随着林龄的增加,山杨在0~100 cm各土层土壤容重(1.07~1.69 g·cm-3)和土壤全K含量(4.32~4.72 g·kg-1)均表现出成熟林近熟林中龄林,而土壤含水量(7.35%~24.39%)从高到低为中龄林近熟林成熟林。土壤全N含量(0.28~2.76 g·kg-1)、土壤全P含量(0.46~1.37 g·kg-1)先增加后降低,即近熟林成熟林中龄林,而土壤p H值(5.03~5.98)变化规律为先降低后增加,表现为成熟林中龄林近熟林。土壤有机质含量(2.64~31.99 g·kg-1)的变化规律较为波动,在0~20 cm土层为近熟林中龄林成熟林,但在20~100 cm土层则呈现出相反的变化规律。(2)各林龄林地土壤容重、土壤全K含量随着土层深度的增加而增加,土壤含水量、土壤有机质含量、N、P含量随着土层深度的增加逐渐降低,土壤p H值随着土层深度的增加呈先升后降的变化趋势。(3)土壤理化性质各指标相关性分析表明,土壤含水量与土壤容重呈极显著负相关,与土壤有机质、全N呈极显著正相关;土壤容重与土壤有机质、全N呈极显著负相关;土壤p H值与土壤全K呈极显著负相关;土壤有机质与全N呈极显著正相关,与土壤全K呈极显著负相关;土壤全N与土壤全P呈极显著正相关,与全K呈极显著负相关;土壤全P与土壤全K呈极显著负相关。     

渭北旱原应用保水剂造林试验

在千阳县研究了保水剂对渭北旱原土壤含水量和侧柏幼树生长的影响,研究表明,保水剂以每穴施2.5g最优.在60cm土层内,平均土壤含水量在9.5％以下时,植穴施固体保水剂对林木成活率和生长量不起作用,甚至不利于林木成活与生长.土壤含水量11.5％以上施固体保水剂,其成活率和生长量高于对照,随着土壤含水量增加,施固体保水剂效果越好.     

施用鸭粪对杉木生长及其改土效应研究

对杉木林施用鸭粪的试验研究结果表明,施用鸭粪对林地土壤的理化性质有较好的改善作用,同时明显地促进杉木林的生长。在施肥后的3 a时间中,土壤的质地、结构得到改善,通透性能明显增强,土壤密度由施肥初期的平均1.20 g.cm-3减小到第3 a的1.13 g.cm-3,田间持水量从32.19%提高到42.41%,土壤孔隙度3 a内增加了6.84%,土壤有机质、全氮、水解氮、有效磷、速效钾等养分含量依次增加了9.08 g.kg-1、0.216 g.kg-1、20.48 mg.kg-1、5.18 mg.kg-1和37.39mg.kg-1,而pH值提高了0.63;3 a内林分年均胸径、树高、单株材积分别比对照增加了0.43 cm、0.30 m和0.007 4 m3。     

北京地坛公园古侧柏土壤理化特性研究

以北京地坛公园古侧柏为研究对象,采用环刀法和烘干法分析了北京地坛公园古侧柏土壤理化特性。结果表明:1)古侧柏土壤含水量为14.54%;2)土壤容重为1.59 g/cm3;3)土壤的总孔隙度、毛管孔隙度和非毛管孔隙度分别为26.86%,40.14%和13.28%;4)土壤紧实度为0.51 kg/m2。     

三匹虎自然保护区森林土壤理化性质的研究

在广西三匹虎自然保护区的森林环境中,于不同的海拔高度带设置了研究其森林土壤理化性质用的9个调查样地,分别采集土样测定其土壤理化性质.结果表明:(1)0～100 cm土层的土壤容重为0.54～1.44 g·cm-3;土壤总孔隙度为53.93 %～72.00 %;土壤通气度为8.28 %～30.55 %;土壤有效贮水量为819.8～1 707.0 t·hm-2.(2)0～40 cm土层土壤的pH值为3.92～4.56;土壤的平均全氮含量和碳氮比分别为1.96 g·kg-1和15.5;土壤的平均全磷和速效磷含量分别为0.62 g·kg-1和1.53 mg·kg-1;土壤的平均全钾和速效钾含量分别为15.25 g·kg-1和97.5 mg·kg-1.(3)三匹虎自然保护区的森林植被在改良其森林土壤的物理特性,提高土壤贮水能力,丰富森林土壤有机质及其N、P、K的含量等,增强土壤涵养水源及肥力上都具有显著的生态功能.     

土壤管理制度对苹果园土壤物理性状的影响

以龙丰苹果园土壤为研究对象,分别在覆盖、生草、免耕和清耕4种土壤管理制度下进行研究。结果表明,各处理的土壤温度在5~19℃之间波动,覆盖和生草处理的土壤温度变化幅度最小,分别为12.7℃和12.3℃;土壤含水量覆盖最高,其次是生草,清耕处理的土壤含水量最低。与清耕处理相比,生草处理明显降低土壤容重,其中0~20cm土层下降0.06g/cm~3;20~40cm土层下降0.14g/cm~3。土壤孔隙度在20~40cm土层生草与覆盖处理差异显著,与免耕、清耕处理之间的土壤孔隙度差异极显著。     

海州露天矿土地复垦示范区土壤综合质量评价

为有效地治理和改善矿区恶劣生态环境,使废弃的土地资源得以充分利用,通过对阜新海州露天矿土地复垦示范区土壤有机质、全N、有效P、速效K、EC、pH值、含水量、容重、紧实度等指标进行测定,开展了复垦土壤质量综合评价。结果表明:不同复垦示范区土壤质量差异较大,沙打旺、冰草示范区土壤质量最好;杨树、油松示范区次之;耕地、侧柏示范区土壤质量较差。     

Armillaria ostoyae in managed coniferous forests in Kastamonu in Turkey

Although several Armillaria species have been reported in Turkey, there is little information about their ecology in Turkish forests. In this study, we investigated five forest stands, approximately 5–74 ha in size, in Kastamonu province in the Black Sea Region of Turkey for the presence of Armillaria species in stumps and logs. The stands were mixed Abies nordmanniana ssp. bornmülleriana and Pinus sylvestris forests managed using a selective cuttings system; the proportion of fir in the total number of stems and stumps ranged from 36 to 98%. Based on sequence analysis of the internal transcribed spacer and intergenic spacer regions of the rDNA, all rhizomorphs sampled from the stumps and logs were of Armillaria ostoyae. The size of the genets was estimated with random amplified microsatellites analysis of the isolates and ranged from single stumps to approximately 450 m². One to seven genets were found in each stand. These results indicate that the genets had arisen from spores and vegetative spread was limited on most sites.     

上海中央公园特大银杏树白蚁防治探讨

通过对上海松江中央公园内65株特大银杏树白蚁为害情况的调查,发现该公园银杏受害率为100%,其中存在活白蚁的银杏占总量的56.9%,采用毒土处理、粉剂疗法、建立白蚁监测点等措施,经过两次灭杀,活白蚁的灭杀率达到92.3%和93.3%,从而使存在活白蚁银杏树的比例从56.9%下降到2.7%,白蚁发生情况明显降低。       

我国食品中农药残留研究进展

随着人们安全健康意识提高,食品中农药残留问题更加受到重视,本文综述了样品预处理研究进展及农药残留快速检测技术研究进展,并简单分析介绍各种方法的优缺点。     

建平半干旱地区石质山地造林技术研究

研究了不同植物在石质山地的造林成活率、土壤化学性质随造林年限的变化和造林措施对土壤化学性质和植物胸径、树高年净生长量的影响。结果表明：不同植物在石质山地的成活率在21%～85%之间,其中白榆和沙打旺的成活率分别为81%和85%,而小叶杨、刺槐、栾树的成活率均在70%左右;植被能明显提高石质山地不同土层的有机质、全N、P2O5含量,但提高程度随土层深度、养分种类和造林年限的不同而不同;在同一土层,生物复合肥料、菌剂和保水剂均显著提高土壤有机质含量（p〈0.01）并显著降低土壤P2O5含量（p〈0.01）;只有保水剂可引起土壤全K含量的明显升高;生物复合肥料、菌剂和保水剂均显著提高白榆、小叶杨、刺槐、栾树树高和胸径的年净生长量,但保水剂的提高程度最高。     

植物DNA甲基化研究进展

植物经常暴露在各种生物和非生物的胁迫之下,这些胁迫会影响植物的生长发育和繁殖并最终导致植物死亡。为了抵御不利的环境条件,植物已经进化出复杂而精细的网络来感知胁迫并激活防御系统。为此,植物激活许多信号转导通路,这些信号转导通路可以改变一些胁迫响应基因的表达,从而引起植物形态、生理和生化的改变以适应逆境。DNA胞嘧啶甲基化是高等真核生物的主要表观遗传机制之一,在维持基因组稳定性和调节基因表达方面起着关键作用。表观遗传变异比遗传变异更为灵活。一旦环境条件发生变化,为了适应新的环境植物都会发生表观遗传的改变。许多研究表明DNA甲基化参与植物的发育和应激反应。基于相关研究对DNA甲基化进行了综述,对植物逆境胁迫有重要意义。     

木材碳封存研究进展

碳封存可以分工业封存和生物封存, 工业封存包括地质封存、海洋封存、矿石碳化以及工业循环利用, 这些方法能快速回收CO₂, 但工艺流程技术复杂, 成本较高。木材碳封存是生物碳封存的一种类型, 树木光合作用吸收的碳主要存贮在木材中。运用木材密度、微密度等检测仪器, 通过确定木材密度变化, 结合其含碳率来计量木材的碳封存过程以及封存过程中碳的分配格局, 同时研究其与环境因子的相关性, 可以为研究森林的碳吸收动态提供便捷的方法和科学的依据。     

Natural regeneration in patch clear-cutting in Picea abies stands in Southern Finland

Abstract

The success of natural regeneration on patch clear-cuts in Norway spruce stands in Southern Finland was examined in terms of stocking and tree height. The experiment was established in mature spruce stands in the submesic Myrtillus (MT) site type. In each of the eight study sites, three plots were treated with clear-cutting and planting, clear-cutting with partial tree retention and planting, and patch clear-cutting without site preparation, respectively. In three of the study sites, one plot with patch clear-cutting and site preparation was established. Each plot was 1 ha, out of which three patches of 40×40 m were clear-cut in the patch treatments. 10–11 years after cutting, the patches had on average 1316 crop trees ha^–1, of which 91% were spruces. Some 27% of the stands were up to the target stocking level (≥1600 ha^?1), and 36% were at least satisfactory (≥1300 ha^?1). Site preparation did not yield greater stocking levels on patches, but that result is ambiguous due to a difference in initial stocking. The average spruce tree height in the patches (0.76 m) was much smaller than in the case of clear-cutting and planting (2.42 m). In conclusion, the patches had been restocked tolerably well with spruce and birch for practical purposes during the 10- to 11-year period, but the regeneration process had been very slow compared to clear-cutting and planting.     

Tree regeneration in patch cutting in Norway spruce stands in northern Finland

The study focused on the success of regeneration on patch cuts in spruce-dominated stands in terms of stocking and tree height. It was based on an experiment in the Kainuu region in northern Finland. The experimental design included 8 stands with 58 clearcut patches of variable size (0.09–0.37?ha), on which either natural regeneration without site preparation or site preparation and planting of Scots pine was applied. A regeneration survey was conducted 13–15 growing seasons after treatments. Patches without site preparation had been restocked quite well from natural seed sources. The average number of trees was about 11,000?ha^?1, of which 1700?ha^?1 crop trees. With site preparation and planting, the stocking levels were also very high, 25,000 and 2100?ha^?1, respectively. One hundred percent of the planted patches and 75% of the naturally regenerated patches had an acceptable density. Restocking was equally good across the range of patch sizes. Tree growth had been somewhat slower in the smallest patches than in the largest ones in the range. Natural regeneration was capable of yielding good regeneration results in most patches, especially when site preparation was applied. Stocking levels and height development were higher yet in the planted patches.     

Changes in micropores in dry wood with elapsed time in the environment

To investigate the changes in microstructures of wood with elapsed time in the environment, CO₂ adsorption onto dry wood was measured at ice-water temperature (273 K) for samples aged from 0.1 years to over 1000 years. The micropore size distribution was obtained using the Horvath-Kawazoe method. Micropores smaller than 0.6 nm in wood decreased in number with elapsed time in the environment, and a negative correlation was found between cumulative pore volume for pores smaller than 0.6 nm and elapsed time in the environment. Cumulative pore volume in the 1000-year sample was almost half of that in the 0.1- year sample. Micropores smaller than 0.6 nm in wood with a few decades or more of elapsed time increased in number after rewetting and drying. Consequently, microstructures of wood with longer time elapsed in the environment were considered to be more stable, because of longer-term thermal motion and possibly more repeated moisture adsorption and desorption and/or temperature variation in the environment.