黄土丘陵沟壑区不同草本植物生长期植物纤维毯对沟道边坡产流产沙的影响

为探究植物纤维毯在黄土丘陵沟壑区的适用性以及不同植物生长期植物纤维毯的水土保持效益,以内蒙古呼和浩特市清水河县为研究区,采用野外人工模拟降雨试验方法,对植物生长期为58,81,132天的直播草本边坡和植物纤维毯边坡径流产沙进行模拟试验。结果表明:(1)植物纤维毯护坡措施可显著延长边坡产流时间,并且产流时间随着植物生长期的增加而增加。在植物生长期为58,81,132天时,植物纤维毯边坡产流时间分别为86,110,243 s,明显大于裸坡(50,70,111 s)和直播草本边坡(73,83,123 s)。(2)随着植物生长期的增加,植物纤维毯边坡径流量从13 125 mL降至5 478 mL,产沙量从73 g降至22 g;直播草本边坡径流量从25 573 mL降至14 340 mL,产沙量从201 g降至82 g。(3)植物纤维毯护坡措施减流效益为55%～78%,减沙效益为71%～89%。(4)坡面植被高度、盖度是植被生长状况中影响径流产沙的主要因子,径流量、产沙量与植被高度和盖度呈多元线性函数关系。植物纤维毯能够有效降低黄土丘陵沟壑区沟道边坡土壤侵蚀,减少产流。     

植被护坡研究进展与展望

在回顾国内外植被护坡发展简史的基础上,总结了植被护坡的功能,详细介绍了植被护坡机理的研究进展。从植物的截留降水、削弱溅蚀和抑制地表径流等方面分析了植被护坡的水文效应,并从植物单根抗拉强度、根-土相互作用、根-土复合体及边坡稳定分析等方面分析了植物护坡的力学效应,最后探讨了植被护坡的发展方向。     

城市河渠生态护坡技术效益对比——以北京市新开渠为例

在城市河渠整治工程的边坡防护中,已初步使用生态防护方式,但各种边坡防护措施的防护效果差异明显.应科学地采用生态边坡防护措施或生态与工程相结合的防护措施,使河道坡面稳定以实现生态治理的目的.通过建立边坡绿化试验小区,选择液体喷播、铺设生态植被毯、三维植被网等生态护坡技术,对各自的经济、生态效果进行分析,并对各类生态护坡技术进行评价.结果表明,铺设生态植被毯是一项经济可行、防护效果理想的技术措施.     

生态型框技术在护坡工程中的抗侵蚀效应研究

试验研究了一种生态护坡技术——生态型框护坡的抗侵蚀效应。试验表明,生态型框护坡的抗侵蚀效应明显优于人工撒草护坡技术,随着植被覆盖度的提高,生长的植物根系起到了固土保土作用,对于减少土壤流失量有着较好的效果。     

青藏高原东北地区边坡恢复技术探讨

近年来高寒地区生态环境问题备受关注,青藏高原特殊的地理位置和气候条件,使其不仅影响周围区域的生态安全,还威胁到全国的生态安全。在介绍青藏高原东北地区不同的边坡类型,以及讨论边坡喷播技术、边坡水泥抹面技术、植生带护坡技术、生态草毯护坡技术、植被混凝土边坡防护技术的基础上,通过实地调研,对比分析得出,无土生态草毯护坡技术和植被混凝土边坡防护技术可以在气候环境比较恶劣的青藏高原东北地区快捷、有效地修复各类边坡。     

水库消落带消浪植生型生态护坡技术应用

以消浪固土为生态护坡目标,通过设计一种自锁定消浪植生型生态护坡构件,最大限度地降低波浪冲刷力,保护消落带表层土壤,并在构件植物栽植孔中种植牛鞭草、狗牙根、野地瓜等水土保持植物,在水陆交界面形成一个连续的波浪缓冲带,同时有效发挥植物根系的固土护坡作用,从而实现生物—工程相结合的消落带坡面防护。该技术具有稳定性高、适应性强、消浪作用好以及环境友好的特点,可显著减轻波浪对消落带坡面的侵蚀作用,提高植被保存率。     

三种生态护坡形式的水土保持效果研究

选取北京市昌平区朱辛庄水土保持示范基地内的4个径流小区为研究对象,其中3个分别进行了生态植被毯护坡、椰纤植生毯+客土护坡、六棱花饰砖护坡,1个为空白对照。在2015年对4个径流小区的产流和产沙数据进行了监测分析,结果显示:3种生态护坡形式均具有一定的水土保持效果,都能够有效地减少坡面的水土流失;3种生态护坡中椰纤植生毯+客土护坡的保水效果最好,六棱花饰砖护坡的保土效果最好。综合3种生态护坡的产流、产沙数据分析认为,椰纤植生毯+客土护坡的综合水土保持效果要优于其他2种生态护坡形式,可以在研究区附近推广使用。     

森林保持水土涵养水源的效应及评价

森林保持水土、涵养水源的作用层次主要是林冠和林下植被层、枯枝落叶层、根系土壤层,通过这三个层次对降水进行调节,具有截持降水、增加降水入渗、改善土壤性质、吸收和阻延地表径流、抑制土壤蒸发、固土护坡等功能,从而有效避免土壤溅蚀、增强土壤抗冲能力、涵养水源并预防地质灾害的发生。枯枝落叶层是森林保持水土的重要力量。完整的森林系统不会加重水土流失。在干旱的季节或年份,森林会加重土壤干旱的说法缺乏科学依据。     

湿喷植被混凝土生态护坡技术在水渠边坡工程中的应用

[目的]验证湿喷植被混凝土生态护坡技术的先进性与实用性,为工程边坡生态防护提供参考。[方法]将湿喷植被混凝土生态护坡技术应用于湖北省鄂州市花马湖水系连通渠护坡工程,现场观测了护坡和水土保持效果、植物盖度、植株密度、植物平均高度以及物种多样性指标。[结果]湿喷植被混凝土生态护坡技术能促使边坡稳定。所用基材能较好地附着于坡面,未出现冲沟和滑塌,水土保持较好,成功解决了基材可喷射性和坡面附着性之间的根本矛盾;1个月后坡面整体植被覆盖率达到90%以上;缓坡区的Shannon-Wiener多样性指数、Pielou均匀度指数、Simpson优势度指数与陡坡区均较为接近,但与自然边坡存在差异;湿喷综合成本比干喷节约5%～15%。[结论]湿喷植被混凝土生态护坡技术作为干喷植被混凝土生态护坡技术的升级版,具备显著的先进性,能用于工程边坡的生态防护。     

不同降雨强度条件下植被毯护坡技术的产流特性

为了研究不同气候条件下植被毯技术的适用性,分析不同降雨强度条件对径流、入渗系数、入渗深度的影响,设置3种降雨强度(0.56、1.01、2.02 mm/min),通过侵蚀槽填土并布设各类植被毯,模拟施工边坡,并设置无覆盖对照组,使用侧喷式人工降雨大厅对侵蚀槽进行人工模拟降雨试验.结果表明:1)植被毯能够增加径流入渗,在降雨强度为1.01 mm/min时,麦秸秆植被毯和椰丝纤维植被毯最多分别能够增加27.7％和28％的入渗量;2)不同材料植被毯径流过程有明显的差异,在降雨强度为0.50、1.01mm/min时,入渗系数为麦秸秆＞椰丝纤维,降雨强度为2.02 mm/min时,入渗系数为椰丝纤维植＞麦秸秆;3)同种材料不同质量的植被毯径流总量有较大差异,同种材料中,200 ～ 300 g/m2的植被毯在3种降雨强度条件下均能够取得较其他质量植被毯更好的保水效果.     

低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响

【目的】以富士（Fuji）、 秦冠（Qinguan）嫁接在平邑甜茶（Malus hupehensis Rehd.）上的当年生盆栽苗为试验材料,采用砂培方法,研究了缺氮胁迫和干旱对富士和秦冠生长情况、 光合参数、 植株各部位氮磷钾含量及氮素利用效率的影响,分析比较了低氮干旱条件下富士和秦冠生长及氮素利用的差异,以期为果树生产高效肥水利用提供理论指导。【方法】试验共设四个处理: 正常氮正常水（ZZ）、 低氮正常水（DZ）、 正常氮干旱（ZG）、 低氮干旱（DG）。氮素和水分均设置两个水平,分别为正常氮（6 mmol/L NO-3-N）、 低氮（0.3 mmol/LNO-3-N）、 正常供水（保持盆中砂子相对含水量为饱和含水量的80%~85%）、 干旱处理（保持盆中砂子相对含水量为饱和含水量的60%~65%）。【结果】富士和秦冠的生物量（茎和叶）、 株高茎粗等生长指标以及光合速率、 气孔导度、 蒸腾速率均为正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）,并且相对应处理下秦冠的以上指标均高于富士;正常供水下,缺氮处理使富士、 秦冠的根冠比比正常氮处理均有所增加,富士提高了2.05%,秦冠提高了22.40%。富士和秦冠的氮、 磷、 钾含量均表现出正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）; 氮、 钾元素含量在植株各部位的分布顺序依次是叶＞根＞茎,磷元素则是根＞叶＞茎;光合氮素利用效率（PNUE）和氮素利用效率表现为秦冠处理之间差异极显著,富士处理之间差异不显著;秦冠的PNUE和NUE明显高于富士,在低氮正常水（DZ）处理下,秦冠氮肥利用率比富士高42.07%,在低氮干旱（DG）处理下高64.14%;低氮胁迫下富士和秦冠的NUE显著提高,并且秦冠提高的幅度高于富士。【结论】施用氮肥能够显著提高富士与秦冠的干物质量,同等水肥条件下,秦冠生长优于富士;水分亏缺会减少叶片对氮的吸收,干旱条件下适度增施氮肥,可提高果树的抗旱能力;低氮干旱胁迫下秦冠的生长指标、 光合指标及氮素利用效率指标均优于富士,表现出较强的抗低氮干旱胁迫的能力。     

Pasture Vegetation Elemental Analysis by Laser-Induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is a new technique for the analysis of plant material. This study investigates the application of LIBS to pasture-based plant samples. The LIBS measurements were obtained from pelletized pasture samples (100 samples) that had been also analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES) following microwave digestion for calibration and comparison purposes. Comparisons for elements sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), boron (B), phosphorus (P), and sulfur (S) showed that LIBS could be used for almost all the standard profile total elements with concentrations down to low mg/kg levels (observed error of Na: 0.024 percent, K: 0.18 percent, Mg: 0.016 percent, Ca: 0.073 percent, P: 0.017 percent, Mn: 31 mg/kg, Fe: 150 mg/kg, Zn: 6.6 mg/kg, and B: 1.1 mg/kg). Elemental analysis at less than mg/kg levels was not possible using LIBS. The elements S and Cu were particularly difficult to analyze with reliability using LIBS at the concentration levels found in the plant samples. Replacing microwave digestion and subsequent ICP analysis with a direct analysis of dried plant samples using LIBS has the potential to improve the productivity and reduce the cost of testing.     

Faculty positions:Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Macroinvertebrates in North American tallgrass prairie soils: effects of fire, mowing, and fertilization on density and biomass

The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils.     

Variation in quality parameters between and within 14 Nordic tree fruit and berry species

Abstract

A 3-year study was carried out to investigate quality parameters in 14 tree fruit and berry species grown in southern Norway. The species were blueberry, apple, aronia, sour cherry, sweet cherry, red raspberry, strawberry, blackcurrant, gooseberry, red currant and elderberry, harvested along with wild bilberry, cloudberry and lingonberry. Significant differences between species were identified for all quality parameters. The coefficient of variation between species was lowest for pH (12.5%), dry matter (18.9%) and soluble solids (25.3%), followed by titratable acids (59.3%), total phenolics (83.8%), antioxidant capacity FRAP (85.7%) and antiradical power by the DPPH-assay (97.8%), total monomeric anthocyanins (132%) and ascorbic acid (137%). Average coefficient of variation within species were lower and ranged from 4 (pH) to 62% (ascorbic acid). Only the FRAP values were significantly affected by harvesting year with lower levels in 2004 than in 2005 and 2006. There were significant interactions between species and harvesting year for dry matter, soluble solids, pH, ascorbic acid and FRAP. The results indicate generic ranges in composition within species independent upon growing location and climate, and the composition of the tree fruits and berries is not likely to deviate from these ranges. It is concluded that desirable composition of tree fruits and berries and their products should primarily be achieved by selection among species rather than searching fors broadened variation within individual species.     

Potassium Fixation and Release Characteristics in Rhizosphere and Nonrhizosphere Soils for a Rapeseed–Rice Cropping Sequence

Potassium (K) fixation and release in soil are important factors in the long-term sustainability of a cropping system. Changes in K concentration and characteristics of K fixation and release in rhizosphere and nonrhizosphere soils in the rapeseed (Brassica napus L.)–rice (Oryza sativa L.) rotation were investigated using a rhizobox system. The concentrations of different forms of K in both rhizosphere and nonrhizosphere soils decreased with plants compared to without plants, regardless of K fertilizer application. Potassium uptake by crops mainly came from the rhizosphere soil. In the treatment without K fertilizer (–K), the main form of K supplied by the soil to the crops was 1.0 mol L^?1 nitric acid (HNO₃) nonextractable K, followed by nonexchangeable K, and then exchangeable K. In the treatment with K fertilizer (+K), the main K forms supplied by the soil to the crops were exchangeable K and nonexchangeable K. The amount and rate of K fixation after one cycle of the rapeseed–rice rotation was greater in rhizosphere soil than in nonrhizosphere soil. The amount and rate of K fixation of soil in the +K treatment were significantly less than in the –K treatment. The cumulative amounts of K released with 1.0 mol L^?1 ammonium acetate (NH₄OAc) and 1.0 mol L^?1 HNO₃ extraction increased with the increasing numbers of extractions, but the K-releasing power of soil by successive extraction decreased gradually and finally became almost constant. The release of K was less in rhizosphere soil than in nonrhizosphere soil. The release of K in the +K treatment was similar to that in the –K treatment in rhizosphere soil, but the K release in nonrhizosphere soil was greater with the +K than the –K treatment. Overall, the information obtained in this study will be helpful in formulating more precise K fertilizer recommendations for certain soils.     

Electron donor and pH relationships for biologically enhanced dissolution of chlorinated solvent DNAPL in groundwater

Biologically enhanced dissolution offers a method to speed removal of chlorinated solvent dense non-aqueous-phase liquid (DNAPL) sources such as tetrachloroethene (PCE) and trichoroethene (TCE) from aquifers. Bioremediation is accomplished by adding an electron donor to the source zone where fermentation to intermediates leading to acetic acid and hydrogen results. The hydrogen and possibly acetic acid are used by dehalogenating bacteria to convert PCE and TCE to ethene and hydrochloric acid. Reductive dehalogenation is thus an acid forming process, and sufficient alkalinity must be present to maintain a near neutral pH. The bicarbonate alkalinity required to maintain pH above 6.5 is a function of the electron donor: 800 mg/L of bicarbonate alkalinity is sufficient to achieve about 1.2 mM TCE dechlorination with glucose, 1.7 mM with lactate, and a much higher 3.3 mM with formate. Laboratory studies indicate that in mixed culture, formate can be used as an electron donor for complete conversion to ethene, contrary to pure cultures studies indicating it cannot. Various strategies can be used to add electron donor to an aquifer for DNAPL dehalogenation while minimizing pH problems and excessive electron donor usage, including use of injection-extraction wells, dual recirculation wells, and nested injection-extraction wells.     

Biodiversity and ecogeography of wild Lactuca spp. in some European countries

Staff members of the Department of Botany of Palacký University in Olomouc and Gene Bank Department – Workplace Olomouc, Research Institute of Crop Production in Prague, Czech Republic, conducted an expedition in seven European countries (Austria, Czech Republic, France, Germany, Italy, the Netherlands, Switzerland) in August/September 1999 to collect wild Lactuca spp. germplasm and study its geographic distribution, ecology and biodiversity. During the mission, more than 600 locations were visited resulting in the collection of 602 seed samples (accessions) of wild Lactuca species and 13 seed samples of related genera (Chondrilla and Mycelis). Lactuca serriola f. serriola, L. serriola f. integrifolia, L. saligna and L. viminea subsp. chondrilliflora were prevalent in southern Europe (Italy, France), however, only L. serriola was common in central and western Europe (Austria, Czech Republic, Germany, Netherlands, Switzerland). The greatest diversity of Lactuca species was found in France, where also the most seed samples (165) were collected. The most characteristic habitats with a high density of Lactuca spp. populations were observed along roads and highways, grassy ditches, ruderal communities, and dust-heaps. Natural infections by powdery mildew (Erysiphe cichoracearum) and downy mildew (Bremia lactucae) on some wild Lactuca spp. were observed. Recent observations concerning the geographic distribution, population structure, habitats, and natural occurrence of diseases of Lactuca spp. are discussed. This assemblage of genetic resources of Lactuca spp. can serve as the basis of future studies of species diversification, spatial population structure, plant microevolution, domestication processes, and genetic variability of host-parasite interactions.     

Increase in auxiliary photoprotective photosynthetic pigments in wheat seedlings induced by Azospirillum brasilense

Inoculation of wheat seedlings with the plant growth-promoting bacterium Azospirillum brasilense Cd was immobilized in alginate microbeads and, without applying any stress, significantly increased the quantity of several photosynthetic pigments, such as chlorophyll a, chlorophyll b, and the auxiliary photoprotective pigments violaxanthin, zeaxanthin, antheroxanthin, lutein, neoxanthin, and β-carotene. This resulted in greener plants with no apparent visible stress. After monitoring the quantity of photosynthetic pigments for 4 weeks, we observed that inoculated plants had higher quantities of pigments in shoot and stem. The greatest difference in the quantity of all pigments between inoculated and noninoculated plants occurred in the first week of growth. Regardless of treatment, the quantity of pigments in stems was three to four times less than the quantity of these pigments in shoots. Application of Azospirillum, either as liquid inoculant or as alginate microbeads, did not alter the positive effect of the bacteria on pigment production or the positive response of the plants towards A. brasilense Cd inoculation.     

In-situ enrichment and analysis of atrazine-degrading microbial communities using atrazine-containing porous beads

We examined the community composition of microbes that colonized atrazine-containing beads buried in agricultural soils that differed in atrazine treatment history. Bacterial abundance was 5-40-fold greater in atrazine-fortified beads. In beads containing 20 mg atrazine kg⁻¹ buried in soil with a history of atrazine application (conditioned soil), the abundance of Actinobacteria increased approximately 80-fold whereas in control soil, Actinobacteria were enriched only 10-fold and the gamma-Proteobacteria and Planctomycetes increased by 60- and 25-fold, respectively. The gamma-Proteobacteria were enriched by 120- and 230-fold in beads containing 200 mg atrazine kg⁻¹ in conditioned and control soil, respectively. The results demonstrate that BioSep^® beads are a suitable matrix for recruiting a diverse subset of the bacterial community involved in atrazine degradation.