荒漠草原土壤有机质碳稳定同位素特征研究

应用碳稳定同位素分析方法对内蒙古短花针茅荒漠草原土壤有机质及其δ13 C值垂直分布特征、表土δ13C值与建群种-短花针茅δ13 C值的相互关系进行分析,并测定土壤部分理化性质。结果显示:表土有机质含量变化范围为4.17～20.45g/kg;随深度增加,土壤有机碳(SOC)含量呈指数降低,其变化范围为17.98～1.39g/kg,而δ13C值则随剖面深度增加而明显富集,到75cm深度时δ13C值又迅速降低,变化范围为-26.38‰～-13.72‰,变幅>3‰,说明该地区气候和植被状况可能发生过剧烈变化;表土和植物δ13C值分馏程度较其它地区偏大,二者呈极显著相关(r=0.555,P<0.01),进一步说明地上植被状况是影响土壤有机质δ13 C值垂直分布特征的决定性因素。     

不同放牧强度下荒漠草原土壤有机碳及其δ~(13)C值分布特征

以内蒙古短花针茅荒漠草原为研究对象,通过测定不同载畜率下土壤部分理化性质、土壤有机碳含量和δ~(13)C值.探讨随放牧强度增加土壤有机碳深度分布和δ~(13)C值的组成差异特征.结果显示:随深度增加.有机碳含量呈线性急剧降低,变化范围在16.17～6.26 g/kg之间,而土壤有机碳的δ~(13)C值不断增大.变化范围在-22.5‰～-14.3‰.放牧对土壤有机碳的影响主要在0-20 cm土层,且放牧强度越大,有机碳含量越低,有机质分解程度越大,δ~(13)C值越偏正,δ~(13)C值的深度变化特征还表明.土壤剖面形成发育过程中当地气候和植被发生了很大的变化,可能实现了由C_4植物占优势向C_3植物占优势的变迁.     

喀斯特地区坡地土壤有机碳的分布特征和δ^13C值组成差异

以喀斯特地区不同退化程度的两个典型坡地为研究对象,通过测定土壤部分属性与土壤有机碳含量的空间分布特征和δ13值,探讨土壤侵蚀和沉积过程中土壤有机碳(SOC)动态变化及影响因素。结果显示:自然坡地的表层土壤有机碳含量较高(6.3%~16.2%),δ13C值随着坡面向下逐渐降低,范围在-21.7‰~-14.3‰之间,变幅较大;撂荒坡地表层土壤有机碳含量为4.4%~7.4%,δ13C值在-21.4‰~-20.3‰之间,变幅相对较小。表明自然坡地沉积的新有机质要高于撂荒坡地,且两者δ13C值均与地表植被种类显著相关。另外,两个坡地各个地形部位的剖面土壤有机碳含量和δ13C值随深度变化,反映了植物残体的输入及在土壤中分解累积特征,有助于了解坡地土壤成土过程和受到的侵蚀程度。     

黄土高原泾河小流域泥沙碳、氮同位素与生态环境示踪

以泾河(陕西彬县境内)4条支流表层沉积物为研究对象,对其有机质的稳定碳、氮同位素组成进行测定和研究.结果表明,4条河流表层沉积物有机质的碳同位素(δ13C)值变化范围为(-29.1‰)～(-20.4‰),平均值为-25.4‰.其δ13C值从上游到下游都有逐渐偏正的趋势,表明从上游到下游植被覆盖类型的变化影响了沿河表层沉积物有机质的δ13C值.4条河流表层沉积物有机质的氮同位素(δ15N)值和碳氮比(C/N)的变化范围分别为0～4.6‰和1.4～17.2,平均值分别为2.8‰和7.3.从上游到下游其δ15N值逐渐偏正,表明沿岸进入河中的泥沙比例越来越大,人类活动等对自然环境的影响增强.徐家河和拜家河下游采样点表层沉积物有机质的δ15N值有偏负趋势,可能与下游煤炭开采,煤等有机质进入河流表层沉积物有关.因此,对河流表层沉积物中有机质的碳、氮同位素组成特征和变化研究可以揭示流域土壤侵蚀状态和生态环境的变化.     

δ13C方法在土壤有机质研究中的应用

δ13C方法是近年来用于土壤有机质动力学研究的一种新方法,该方法除了具有14C标记法的优点外,还具有无放射性,可以提供长期的标记,并能使所有的土壤有机质组分都能被均匀标记,相对经济、在实验地采样后直接进行研究等特殊优点,从而在土壤有机质及其组分的来源、周转和C3/C4植被的历史变化研究中得到广泛应用。随着该方法的迅速发展以及各种分析δ13C值技术的不断改进,δ13C方法在研究土壤过程特别是土壤碳循环中显示出新的活力。为了推动δ13C方法在国内土壤有机质研究中的应用,本文对影响土壤有机质δ13C值的因素、国内外近年来该方法在土壤有机质研究中的应用和δ13C值的分析方法作了较全面的综述。     

退化喀斯特森林植被自然恢复中土壤有机碳δ~(13)C值特征

采用空间代替时间与稳定性碳同位素技术相结合的方法,研究了茂兰喀斯特森林自然恢复中土壤有机碳(SOC)δ13C值特征。结果表明:整体上SOCδ13C值随恢复进展0~20 cm土层(-25.72‰~-19.91‰)趋正、20 cm土层(-23.76‰~-18.13‰)先趋正后趋负。随土层加深除草灌、灌乔外其他阶段均趋正,草灌阶段上层土与乔木、顶极阶段底层土SOC为C4碳,SOCδ13C值变化受地带性和喀斯特环境的双重影响。群落优势种凋落叶δ13C值(-31.79‰~-16.76‰)随恢复进展趋负,说明生境日益改善,其与0~20cm土层SOCδ13C值呈极显著正相关(R20.96,p0.01)、而与20 cm土层极不相关,说明0~20 cm土层主要为新碳;SOC周转速率随恢复进展递增、随土层加深递减,土壤生化反应具较强表聚性;SOCδ13C值与土壤可矿化碳、易氧化碳含量呈显著的负相关关系(R2-0.50,p0.05),与微生物生物量碳具有一定的负相关关系(R2=-0.389),SOCδ13C值在一定程度上可以指示SOC的活性;喀斯特森林自然恢复是复杂多变、多途径的统一,其中C4植物在恢复中具有重要意义;碳同位素方法与"空间代替时间"方法相结合能较好地重现喀斯特植被更替的历史。     

植物富集~(13)C标记技术的初步研究

<正>稳定同位素13C技术已被广泛用于研究土壤有机碳的周转[1-3]。13C技术可分为自然标记和人工标记两种[4-5]。13C自然标记方法研究土壤碳周转一般用于田间原位试验,要求有C3和C4植物的更替,且要有准确的更替时间。而室内培育实验利用这一方法则需加入较高的外源碳才能使δ13C值有较明     

吉林西部全新世晚期土壤碳酸盐中碳稳定同位素记录的古气候信息

土壤碳酸盐中碳稳定同位素是记录古气候变化信息的重要载体。本文对吉林省西部大安市姜家甸草场土壤剖面中的δ13C值特征进行了详细分析,并在此基础上推得C3、C4植物生物量;结合野外观察到的剖面特征,作者认为全新世晚期以来,该地区气候曾经历过从干-热～湿-暖～干-热的演变过程。现今吉林西部的干旱化环境正是全新世晚期以来气候持续演化的结果。     

贡嘎南山-拉轨岗日山南坡高寒草原生态系统表层土壤有机碳分布特征及其影响因素

为揭示贡嘎南山-拉轨岗日山南坡高寒草原生态系统表层土壤有机碳分布特征及其影响因素。在不同海拔高度取土样测定土壤理化指标,现场调查植物物种数、土壤类型等,研究了该区域0～20cm土壤有机碳分布特征及其影响因素。结果表明:高寒草原生态系统表层(0～20cm)土壤有机碳密度平均为5.1625±1.2786kgm-2,变异系数24.77%。在海拔4424～4804m范围内,随着海拔升高,表层(0～20cm)土壤有机碳密度表现出增加→减少增加→减少的分布特征。相关分析表明,表层土壤有机碳密度与植被盖度、30～40cm地下生物量、10～20cm土壤含水量、海拔高度、坡度、土壤有机质呈正相关关系,而与0～10cm土壤含水量、30～40cm土壤含水量、土壤pH值和土壤速效N呈负相关关系,影响表层土壤有机碳密度最关键的环境因子是30～40cm地下生物量、土壤pH值、土壤有机质和土壤速效N含量。     

黄河源区湿地、草地土壤理化性质和碳氮组成及其稳定同位素特征分析

为探究黄河源区湿地和相邻草地土壤的有机碳和全氮状况,采用野外调查与室内分析相结合,对其理化性质和碳氮组成及其稳定同位素特征进行测定和分析。结果表明,湿地土壤含水量为21.08%~48.95%,容重为0.57~1.46g/cm3,pH为6.4~9.0,全磷含量为34.6~123.44mg/kg,有效磷含量为7.8~71.48mg/kg,有机碳含量为0.53%~16.57%,全氮含量为0.05%~1.47%,δ13 C丰富度介于(-26.65‰)~(-22.10‰)之间,δ15 N丰富度介于1.15‰~5.49‰之间,Corg/N在8.20~11.53之间变化。与湿地邻近的草地土壤含水量变化为13.97%~48.47%,容重变化为0.68~1.42g/cm3,pH为6.1~8.9之间,全磷含量为57.84~143.62mg/kg,有效磷含量为9.74~60.19mg/kg,有机碳含量为0.88%~9.79%,全氮含量为0.09%~0.88%,δ13 C丰富度介于(-25.80‰)~(-21.42‰),δ15 N丰富度介于2.64‰~6.81‰之间,Corg/N在8.60~12.00之间变化。无论是湿地还是草地土壤含水量均50%,但草地土壤的含水量变异范围大于湿地;源区土壤绝大多数呈弱碱性,少部分近中性或呈弱酸性;有机碳和全氮随湿地类型和采样点的不同也存在很大的差异。总体上,湿地土壤的容重、全磷、有效磷、δ13 C、δ15 N、Corg/N低于草地土壤。土壤有机碳氮及其稳定同位素相互间有显著的相关性,土壤有机质的δ13 C表明源区没有C4植物。     

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,     

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.     

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.     

Properties of anaerobically digested and composted municipal solid waste assessed by linking soil mesofauna dynamics and nitrogen modelling

We have studied the effect of anaerobically digested (ADMSW) and composted municipal solid waste (CMSW) on mineralization and foodweb dynamics to verify the hypothesis that ADMSW would immobilize N right after addition to soil in contrast to addition with CMSW. Another hypothesis was that the mesofauna (enchytraeids and microarthropods) would stimulate N release from the decomposer community. We measured excretion of -N and urea-N from the mesofauna and hypothesized that enchytraeids would release urea. ADMSW and CMSW were amended to pots with sandy loam and barley. The pots were divided into treatments with or without mesofauna. Mesofauna, plant N and biomass, soil N and ergosterol (fungal biomass) were measured over a 113-day period of four equidistant samplings. Soil respiration, N mineralization and N release by the mesofauna were modelled from concurrent studies. ADMSW- and CMSW-treated soils initially (<20 days) immobilized N. The amendments did not increase plant growth substantially, and this was probably due to N-limitation in the early stages of plant growth. Enchytraeid abundance was about three times higher in ADMSW- than CMSW-treated soils, indicating that ADMSW contained more labile compounds, bacteria, and microfauna. The mesofauna did not affect N-content, but the cumulated -N excreted by the mesofauna was estimated to be substantial and about one-fifth of total plant N in ADMSW. An explanation for this discrepancy might be that in the absence of the mesofauna, other members of the detrivore and microbivore community performed the mesofauna’s function. Neither enchytraeids nor microarthropods excreted urea.     

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,     

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,     

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.