肠式沙障固沙作用及其结构稳定性研究

通过对肠式沙障沙埋程度、积沙宽度、位移程度及沙障控制区域植被盖度等指标进行调查,分别研究了不同规格、不同类型的肠式沙障稳定性及其所在沙丘植被恢复程度。研究结果表明:品字沙障位移距离最大,移动平均距离达到了58.72 cm,方格沙障移动距离最小,仅为36.11 cm。4 m品字形沙障的移动距离最大,达到了70.67 cm,2 m带状沙障的次之,移动距离为52.33 cm,说明规格越大,移动程度也越大。方格沙障铺设沙丘的植被盖度较大,其中4 m×4 m方格沙障铺设沙丘植被盖度达到最大。     

荒漠区沙障设置成本核算及阻沙效果、植被恢复情况研究

在石羊河下游干旱荒漠区设置不同材料、不同规格的沙障,本文选择稻草、麦草、玉米杆、芨芨为沙障材料,按照方格式1.5 m×1.5 m、2 m×2 m、2.5 m×2.5 m,行列式1.5、2、2.5 m的规格布设试验,通过核算各材料及各规格成本及调查阻沙效果和植被恢复情况,得出:同一规格下玉米杆的成本最低,麦草、稻草、芨芨成本依次增加;在方格式中各材料均为2.5 m×2.5 m成本最低,2 m×2 m次之,1.5 m×1.5 m成本最高;行列式中各材料均为2.5 m规格成本最低,2 m次之,1.5 m成本最高;各材料中芨芨材料沙障的积蚀高度最大,麦草沙障的最小,同一材料方格式高于行列式,各材料中麦草的凹曲面高度最深,芨芨的最浅,同一材料行列式深于方格式;各材料、各规格间植被种类没有差异,都以沙米为优势植被,同一沙障材料的行列式和方格式植被恢复情况差异不明显,不同沙障材料间植被恢复情况差异较明显,具体为稻草沙障植被恢复情况最好,其次为麦草沙障,芨芨沙障最低。     

草方格在防风固沙工程中的应用

设置草方格沙障是防风固沙方法之一,它通过增加地表粗糙度,有效地控制风速,降低实际风力作用,来实现固定流沙并阻止沙丘前进。该文总结了草方格在防风固沙工程中的制作方法、设置技术和应用实例。     

机械沙障对植被恢复的影响

在治理流沙过程中,工程措施治标,生物措施治本;工程措施和生物措施有机地结合,可以彻底降伏沙龙,达到从根本上治理流沙的目的.巴盟治沙综合试验站在极度沙漠化的乌兰布和沙漠东缘开展研究,在裸露沙丘表面设置粘土沙障和草方格沙障,障内人工栽植各种固沙植物,结合封育恢复天然植被.用这些措施建造的多种类型防风固沙植被,取得了良好的生态效益、社会效益和经济效益.本文就试验站内沙障的设置方法及今后的植被建设问题综述如下:一、机械沙障的设置方法根据风沙运动的规律和特点,93%的沙粒都集中在近地表层10厘米高度范围内.因此,一般情况下沙障高度要求在10厘米～15厘米.沙障的方向应与主风向垂直,夹角要在90°～100°之间.粘土沙     

宣化县黄羊滩流动沙地草方格沙障固沙技术研究

该文在对宣化县黄羊滩流动沙地风沙流结构野外调查的基础上,进行了流动沙地草方格沙障固沙技术试验研究.结果表明:草方格沙障以2m×2m与3m×3m这2个模式防护效果好且省工省料,是最理想的模式.沙障设置后形成了稳定的沙面,在雨季播种了沙蒿、沙打旺等固沙植物,2a后沙障腐烂,固沙植物取代了沙障的防风固沙作用,使流动沙地永久固...     

呼伦贝尔沙地风蚀坑综合治理技术研究

在呼伦贝尔沙地鄂温克旗锡泥河东苏木亚日盖嘎查草原风蚀坑,根据本地区沙障材料成本实际情况,结合风蚀坑面积大、坡度大、治理难度大的特点,采用草方格沙障的1m×1m网格设计,6月初雨季期间,沿着沙障边缘人工点播杨柴和沙打旺,播种量4kg/667m2,混播比例杨柴∶沙打旺为3∶1。采用草方格沙障与灌草混播综合治理技术治理风蚀坑能够取得明显固沙效果。造林2a后,植被盖度明显增加,土壤理化性质明显改善,土壤风蚀减少。     

草方格铺设机构的研究与设计

草方格铺设机构是草方格铺设机器人的重要执行机构，其包括纵向铺设机构和横向铺设机构两大部分。纵向铺设机构利用压草盘将草压入沙中，铺设长度连续、间隔1m的草沙障；横向铺设机构用插刀每隔1m插草一次，在纵向草沙障三个空档中同时插入长度为850～1000mm的草沙障。此机构大大提高了草方格铺设的质量和效率，适合在恶劣的沙漠环境中作业。     

民勤流沙治理中机械沙障的防风固沙效益分析

通过分析研究民勤流沙治理中机械沙障的防风固沙效益,对设置的6种不同类型沙障进行测定和分析,得出如下结论:机械沙障设置后,可以提高流沙下垫面的粗糙度,降低近地表风速,固定流沙,减少风速。6种机械措施相比,塑料网格沙障价值系数最高,依次为:粘土方格沙障、麦草方格沙障、土工编织袋沙障、砾石方格沙障、棉花秆方格沙障。     

207国道植物再生沙障防沙治沙试验研究

207国道90—100 km段公路沙害治理中,采用黄柳在流动沙丘迎风面上设置积沙、聚沙带——植物再生沙障,结合高立式和低立式红柳、芦苇生物沙障,不仅取得了阻沙、固沙、防止沙丘前移的理想效果,同时结合其他人工措施短时间内大幅度增加沙丘的植被盖度,达到了阻沙、固沙和增加植被盖度的双赢目的。     

新恩陶铁路沙柳沙障防风固沙效益研究

对比分析新恩陶铁路不同规格沙柳沙障(1.0 m×1.0m、1.5m×1.5m和2.0m×2.0m)的植被恢复状况及防护效果。结果表明:1.0m×1.0m沙柳沙障的枝条生长状况较好,2.0m×2.0m沙柳沙障内的植被恢复情况较好。沙柳沙障能够降低地表风速,增大地表粗糙度,减少近地表输沙率。其中,1.0m×1.0m沙柳沙障在地表10cm处对风速的降低效果最好,对地表粗糙度的影响最大,输沙范围最小。     

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。     

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.     

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.