京郊河溪近自然治理环境效应分析

选择北京郊县怀柔区怀九河上三处经过不同河流治理方式整治过的河段,其中的四渡河段已实施河溪近自然治理2 a的时间,而一渡河段为传统水工治理,团泉段基本上没采取治理措施。然后定点监测河段的大气湿度、温度,土壤温度以及河岸带植物多样性等生态因子,通过比较分析河溪近自然治理措施对河溪小环境所产生的环境效应。研究结果表明,①河溪近自然治理措施可以增加大气湿度,经过河溪近自然治理的四渡河段比传统水利工程治理的一渡河段水面大气湿度高近5%,河岸带地面大气湿度则高近10%;虽然河岸带的大气湿度不如处于自然状态的团泉段,但水面大气湿度则高了近2个百分点。②与传统水利治理方式相比较,河溪近自然治理措施可以降低周围小气候的温度,调节河岸带地面与水面的温差,四渡河段的温差为0.5℃,是一渡河段的1/3左右。③河溪近自然治理通过恢复河岸带植被缩小土层间的温差,调节土层温度,保持深层土壤水分。④经过河溪近自然治理的四渡河段的植物多样性高于一渡河段,是其3倍左右,恢复了河岸带的植物多样性。     

河溪近自然治理评价指标体系探讨以及应用

河溪近自然治理从河溪生态系统的生态特征、地貌特征和水体特征三个方面入手,针对我国特殊的经济情况和复杂的水域特点,提出了由11个因子组成的河溪近自然评价指标体系,包括：（1）河流的平面形态：（2）河流的横断面形态：⑶河流的水深：（4）水体宽度：（5）岸坡的结构：（6）水流的流速：（7）缓冲带植被宽：⑻水体与河床的接触情况：（9）河道粗木质情况：（10）水质：（11）底栖大型动物。再根据评价结果将河溪生态系统健康划分为四个等级,并对北京市怀柔区的典型河溪——怀九河进行河溪近自然治理评价,发现其处于河溪受到微小的人类活动的侵扰阶段,需要利用河溪近自然治理加以调控。     

河溪近自然治理技术及其评价方法

河溪近自然治理作为恢复退化河溪生态系统的一种重要手段,包括河溪近自然治理评价指标体系与技术措施施工2部分.在分析国内外通行的各种评价方法的基础上,针对我国不甚发达的经济情况和复杂的水域特点,提出了由11个因子组成的河溪近自然评价指标体系,包括1)河流的平面形态;2)河流的横断面形态;3)河流的水深;4)水体宽度;5)岸坡的结构;6)水流的流速;7)缓冲带植被宽;8)水体与河槽的接触情况;9)河道粗木质情况;10)水质;11)底栖大型动物.然后,根据其评价结果对处于不同健康等级的河溪采用相对应的河溪近自然治理技术,从而为我国整体河溪生态系统的恢复和水资源的科学管理提供决策依据.     

河溪生态系统自然性评价指标体系

 从河溪生态系统自然性评价的意义出发,以北京市南沙河为案例,确定河溪自然性评价的3大类指标,即河溪生态特征指标、地貌学指标、水文学指标。在3大类指标中,分别给出各自具有可操作性的亚指标,详细介绍亚指标的计算方法和分级标准。采用指标数量化的评价方法—多目标线性加权函数法,计算河溪自然性综合指数—自然度。应用这种方法对南沙河自然状况进行综合评价的结果是,南沙河整体受到了较为严重的人为干扰,自然状况较差。通过河溪自然性评价图直观反映了南沙河的受扰程度。     

利于河溪生物栖息环境生态工程述评

创造适宜河溪生物栖息环境是河溪生态恢复的主要目标之一。总结了近年来国内外在该领域的研究成果,指出人工化的河溪或平缓顺直的、激流的河溪通常不能为河溪生物提供良好的栖息环境。从构建河道内生物栖息地的措施出发,论述了创造深潭-浅滩结构、改变河床底质以及一些直接提供生物栖息环境等生态河溪建筑物的特点、作用、功能和可行性。最后提出在中国开展创造河溪生物栖息环境生态工程研究应注意的问题和发展方向,以期对我国河道的生态治理有所裨益。     

山东省招远市城东河河道近自然治理设计初探

城市的现代化建设对城市河道提出了更高的要求,传统的工程治理方法已不能满足城市河道多种功能的需要。在山东省招远市城东河河道治理的规划设计中,借鉴国外河道近自然治理的思想,针对城东河河道存在的问题,提出了河道近自然治理的原则,并从河流平面形态、河流垂直断面和护岸三个方面进行城市河道进行近自然治理设计。     

北京郊区河岸带自然性评价指标体系

河岸带是水陆交错带,是河溪的重要组成部分,对人类的生产、生活具有重要的意义.在分析国内外各种对河流评价方法的基础上,结合安达木河水域特点和野外调查,从结构和功能两方面选取了相互匹配的16个指标,采用层次分析和模糊综合评价相结合的方法,构建了河岸带自然性评价指标体系.综合考虑一个平衡河岸带生态系统的特点以及结构和功能等特点,可以将河岸带的近自然程度分为4个等级:自然状态、近自然状态、退化自然状态和退化状态.并以安达木河为例进行评价,评价结果与实际相符合,可作为北京郊区河岸带评价体系.     

河溪缓冲带的生态功能及其管理原则

河溪缓冲带位于陆地生态系统与水生生态系统的之间,是河溪生态系统的重要组成部分,具有多种生态功能。着重介绍了河溪缓冲带的物种天堂、养分来源、稳固河岸、改善水质、景观价值、缓解影响这6种功能。由于现在交通和建设用地的不断增加,河溪缓冲带的人为破坏现象严重,亟需得到科学的管理和恢复。提出了3条缓冲带科学管理的基本原则,为不同地域、不同等级的河溪缓冲带的建设和恢复提供了指导。并以北京市海淀区内的南沙河河溪缓冲带的情况为例,加以印证说明。     

雁栖河溶解氧和氨氮对不同河溪利用方式的响应

河溪是北京郊区居民生产生活的重要场所,在发展农村经济和保护环境中具有重要的地位.通过实地调查北京郊区雁栖河边村民利用河溪(含河岸)的各种活动,分析了近些年来河溪利用方式变化的原因和驱动力.分别选取旅游区河段和村庄区河段作为试验河段,分析水体中溶解氧和氨氮对不同河溪利用方式的响应.结果表明,雁栖河上主要河溪利用方式为筑坝壅水发展民俗旅游业,各种河溪利用方式的主次顺序为:修拦水坝>村庄>养殖>捕捞>引水灌溉>耕作.溶解氧对河溪不同利用方式的响应程度高于氨氮对不同河溪利用方式的响应程度,而有村庄区河段的氨氮浓度容易受村民生活方式的影响.     

城市河流的近自然综合治理研究进展

 城市现代化的加速和人类对自然认识的深入,传统的工程治理技术已不能满足城市河流治理的需要,以生态学为基础、追求人与自然和谐发展的河流近自然治理研究已成为国内外研究的热点。结合国内外城市河流的近自然综合治理研究,探讨今后城市河流研究应注意的内容。     

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.     

Responses of native legume desert trees used for reforestation in the Sonoran Desert to plant growth-promoting microorganisms in screen house

Three slow-growing legume trees used for desert reforestation and urban gardening in the Sonoran Desert of Northwestern Mexico and the Southwestern USA were evaluated whether their growth can be promoted by inoculation with plant growth-promoting bacteria (Azospirillum brasilense and Bacillus pumilus), unidentified arbuscular mycorrhizal (AM) fungi (mainly Glomus sp.), and supplementation with common compost under regular screenhouse cultivation common to these trees in nurseries. Mesquite amargo (Prosopis articulata) and yellow palo verde (Parkinsonia microphylla) had different positive responses to several of the parameters tested while blue palo verde (Parkinsonia florida) did not respond. Survival of all tree species was over 80% and survival of mesquite was almost 100% after 10 months of cultivation. Inoculation with growth-promoting microorganisms induced significant effects on the leaf gas exchange of these trees, measured as transpiration and diffusive resistance, when these trees were cultivated without water restrictions.