不同环境因子及施药量对土壤中唑菌酯残留的影响

在实验室条件下研究了土壤pH、温度、含水量及施药量对新型杀菌剂唑菌酯(E-2-(2-((3-(4-氯苯基)-1-甲基-1H-吡唑-5-基氧)甲基)苯基)-3-甲氧基丙烯酸甲酯)在土壤中残留量的影响。结果表明,在25d的培养时间内,随土壤含水量的增加,唑菌酯在土壤中的残留量减少;土壤含水量增加到60%田间最大持水量时,其残留达最低,为1.81μg/g,而在淹水环境中其残留量增加。随着土壤温度的升高,唑菌酯的残留呈现先降低后升高的趋势,4℃时的残留达最大(3.86μg/g)。土壤pH对其在土壤中的残留具有明显影响,在中性和弱碱性土壤中均具有相对较低的残留。在1～10μg/g施药量时,唑菌酯在土壤中的残留比例随其施药量的增加而少量降低,在药剂浓度为20μg/g时,土壤中唑菌酯的残留率为42.4%。     

硝态氮抑制尖孢镰刀菌侵染促进黄瓜生长的内在生理机制

  【目的】  连作障碍严重影响设施农业的发展。不同形态氮素可影响黄瓜土传枯萎病的发生，然而其内在生理机制尚不明确。通过氮素营养调控植物–微生物互作关系，为防控土传病害的发生提供理论依据。  【方法】  以黄瓜品种津春2号和尖孢镰刀菌黄瓜专化型菌 (FOC) 为试材，进行温室营养液培养试验。设营养液中添加铵态氮不接菌 (A)、硝态氮不接菌 (N)、铵态氮接菌 (AI) 和硝态氮接菌 (NI) 共4个处理。尖孢镰刀菌侵染8天后进行植株样品的采集及测定，包括株高、根长、生物量、病情指数、叶绿素含量、光合特性、叶片温度，并进行了叶肉细胞超微结构的观察，测定了植物全氮、可溶性蛋白及可溶性糖含量。  【结果】  与铵态氮相比，硝态氮营养显著抑制了黄瓜植株枯萎病的发病率，并显著促进了植株的生长以及植株生物量的增加。未接菌条件下，供应铵态氮的植株光合速率、气孔导度、蒸腾速率、羧化效率及表观量子效率均显著高于供应硝态氮的植株；尖孢镰刀菌的侵染导致供应铵态氮的植株叶绿体结构受损，显著降低了其光合速率、气孔导度、蒸腾速率、细胞间隙CO₂浓度、羧化效率及表观量子效率，而病原菌侵染对供应硝态氮的植株叶片光合特性无显著影响。未接菌条件下，供应铵态氮的植株叶片温度及水分利用效率显著低于供应硝态氮的植株；尖孢镰刀菌侵染后，供应铵态氮的植株叶片温度及水分利用率显著增加，而病原菌侵染对供应硝态氮的植株无显著影响。叶片温度与蒸腾速率呈显著负相关关系，而与水分利用率呈显著正相关关系。供应铵态氮的植株根系全氮、可溶性蛋白及可溶性糖含量均显著高于供应硝态氮的植株，从而促进病原菌对供应铵态氮的植株的侵染。尖孢镰刀菌侵染后，供应铵态氮的植株根系可溶性蛋白含量显著增加，可溶性糖含量降低，而尖孢镰刀菌侵染对供应硝态氮的植株可溶性蛋白及可溶性糖含量无显著影响。  【结论】  硝态氮能够有效地抑制黄瓜枯萎病的发生，维持叶绿体结构的完整性，保持黄瓜植株正常的光合作用及生长，并减少碳水化合物向根系的运输，从而抑制病原菌的侵染及病害的发生。在黄瓜的设施栽培中，可适当增加硝态氮肥的施用而减少铵态氮肥的投入，以抑制土传枯萎病发生。     

亚磷酸盐作缓释磷肥对黄瓜体内养分吸收和光合特性的影响

本文以黄瓜为材料,采用营养液培养方法,研究了不同亚磷酸盐浓度对黄瓜植株各部位氮、 磷养分含量, 干重及根冠比, 植株氮、 磷总量以及叶片光合特性的影响。结果表明,黄瓜果实、 叶片和根部氮含量随亚磷酸盐浓度的增加而增加,茎部氮含量没有显著差异; 果实和茎部磷含量随亚磷酸盐浓度的增加呈增加趋势,根部磷含量呈降低趋势,叶片磷含量没有显著差异; 亚磷酸盐浓度增加到一定浓度时,各部位干重显著降低,根冠比没有显著差异; 植株氮、 磷总量随亚磷酸盐浓度的增加有下降的趋势; 黄瓜叶片净光合速率（Pn）随亚磷酸盐浓度的增加呈下降趋势。本研究结果显示,随着亚磷酸盐浓度的增加,植株表现出缺磷效应,对植株养分元素的吸收及光合作用产生了不利影响。该文讨论了亚磷酸盐作为缓释磷肥的可行性。     

三唑酮在黄瓜植株体内的代谢

用薄层色谱法和同位素示踪技术研究了三唑酮在黄瓜植株内的代谢。用~(14)C-三唑酮处理黄瓜植株后,植株体内所含放射性物质大部分是可萃取的。被黄瓜植株吸收的三唑酮,在供试植株体内能迅速转化为三唑醇(R_f=0.63)和两个未知化合物X_1(R_f=0.07)、X_2(R_f=0.02)。其中三唑醇是主要代谢产物,X_1和X_2可能是强极性的水溶性化合物。     

胁迫下不同砧木对嫁接黄瓜叶片氮素代谢的影响

采用营养液栽培,研究了以中国南瓜“360-3×112-2”杂交种和黑籽南瓜为砧木,以“津春2号”为接穗的2种嫁接黄瓜和“津春2号”自根黄瓜成株期在 80 mmol/L NaCl 胁迫12 d 后的生长状况和光合能力,以及试验期间叶片氮素代谢及其关键酶活性的动态变化。结果表明,NaCl 胁迫12 d 后以中国南瓜“360-3×112-2”杂交种为砧木嫁接黄瓜植株的主蔓生长速率、第一片功能叶面积、全株鲜重和光合参数均高于自根黄瓜和以黑籽南瓜为砧木的嫁接黄瓜; 且以“360-3×112-2”杂交种为砧木嫁接黄瓜的生长状况好于以黑籽南瓜为砧木的嫁接黄瓜。NaCl 胁迫处理植株叶片中硝态氮、铵态氮含量、谷氨酰胺合成酶(Gs)活性和可溶性蛋白含量比对照先高后低; 而硝酸还原酶(NR)活性先低后回升,但仍低于对照,说明NaCl 胁迫下,黄瓜叶片氮素代谢能力的降低。不同处理氮素代谢能力的差异其原因在于根系吸收氮源的能力差异。NaCl 胁迫对以“360-3×112-2”杂交种为砧木的黄瓜植株生长抑制较小,氮素代谢能力下降较少,表现出较强的耐盐性,可以作为一个黄瓜耐盐砧木在生产上使用。     

新型杀菌剂啶氧菌酯在田间黄瓜和土壤中的残留消解动态及残留分析

建立了黄瓜和土壤中啶氧菌酯残留量的检测分析方法,对啶氧菌酯在黄瓜和土壤中的消解动态及残留规律进行了研究。啶氧菌酯的最小检出量为3.5×10-11g;在黄瓜和土壤基质中的最低检出浓度均为0.005mg·kg-1。对黄瓜和土壤2种基质,设置了0.005、0.05、0.25 mg·kg-13个添加水平,每个添加水平设置5个重复,啶氧菌酯在黄瓜和土壤中的添加回收率为68.61%~122.4%,变异系数为1.06%~17.2%。田间试验结果表明:啶氧菌酯在天津地区黄瓜和土壤中的残留消解半衰期分别为5.71d和12.9 d,在山东地区黄瓜和土壤中的残留消解半衰期分别为2.70d和10.3 d,在江苏地区黄瓜和土壤中的残留消解半衰期分别为9.76d和14.9 d。距最后一次施药5d时,啶氧菌酯在黄瓜中的最高残留量为0.014mg·kg-1,远低于欧盟规定的黄瓜中啶氧菌酯最大残留限量0.05mg·kg-1。     

NaCl胁迫下不同砧木对嫁接黄瓜叶片氮素代谢的影响

采用营养液栽培,研究了以中国南瓜"360-3×112-2"杂交种和黑籽南瓜为砧木,以"津春2号"为接穗的2种嫁接黄瓜和"津春2号"自根黄瓜成株期在80 mmol/L NaCl胁迫12 d后的生长状况和光合能力,以及试验期间叶片氮素代谢及其关键酶活性的动态变化。结果表明,NaCl胁迫12 d后以中国南瓜"360-3×112-2"杂交种为砧木嫁接黄瓜植株的主蔓生长速率、第一片功能叶面积、全株鲜重和光合参数均高于自根黄瓜和以黑籽南瓜为砧木的嫁接黄瓜;且以"360-3×112-2"杂交种为砧木嫁接黄瓜的生长状况好于以黑籽南瓜为砧木的嫁接黄瓜。NaCl胁迫处理植株叶片中硝态氮、铵态氮含量、谷氨酰胺合成酶(Gs)活性和可溶性蛋白含量比对照先高后低;而硝酸还原酶(NR)活性先低后回升,但仍低于对照,说明NaCl胁迫下,黄瓜叶片氮素代谢能力的降低。不同处理氮素代谢能力的差异其原因在于根系吸收氮源的能力差异。NaCl胁迫对以"360-3×112-2"杂交种为砧木的黄瓜植株生长抑制较小,氮素代谢能力下降较少,表现出较强的耐盐性,可以作为一个黄瓜耐盐砧木在生产上使用。     

[C环-U-14C]丙酯草醚在油菜和水稻中的吸收、运转及分布

丙酯草醚(ZJ0273)是我国创制的一种新型高效油菜田除草剂。本文以[C环-U-14C]-ZJ0273为示踪剂,在实验室条件下,对丙酯草醚在敏感性植物水稻和耐性植物油菜中的吸收、运转及分布规律进行了研究。结果表明:(1)施药后,水稻和油菜对丙酯草醚的吸收量总体呈随时间增加而增加的趋势,且前者大于后者。至384h,水稻对丙酯草醚的吸收量为24.1%,而油菜仅为4.1%,水稻约为油菜的5.88倍。(2)丙酯草醚被油菜和水稻根系吸收后,均主要分布在根部,不易向上运转。水稻根系与地上部(茎叶)的放射性分布比为7.10∶1,油菜则为4.44∶1;水稻和油菜根系中单位质量放射性活度分别是各自地上部的10.36和9.85倍。(3)水稻根系和茎叶单位质量放射性活度分别为9.470 Bq/mg和0.910 Bq/mg,显著高于油菜的3.870 Bq/mg和0.390 Bq/mg。水稻与油菜对丙酯草醚吸收量以及单位质量中积累量的差异可能是丙酯草醚对两者存在选择性的原因之一。     

果园土壤中结合态腐殖质组成特征

通过化学分析方法研究延边地区典型苹果梨园盛果期土壤剖面中结合态腐殖质的空间分布特征.结果表明:(1)A1层(0-22 cm)松结态腐殖质含量表现为苹果梨园＞荒地,高出荒地42.61％,至A2层(22-53 cm)2种土壤松结合态腐殖质含量下降幅度分别60.79％,36.45％;苹果梨园土壤A1层的松结态腐殖质表聚现象比荒地土壤剧烈;在A1、A2层,松结态FA含量表现为苹果梨园＜荒地,HA/FA比以苹果梨园明显高于荒地.(2)苹果梨园稳结态腐殖质含量随土壤深度增加而下降,荒地土壤呈先升后降再升趋势;A1、A2层稳结态腐殖质含量表现为苹果梨园＜荒地;苹果梨园稳结态FA含量随土壤深度增加呈现升一降一升趋势;苹果梨园稳结态HA含量随土壤深度加深而减小,且A2层稳结态FA含量表现为苹果梨园明显小于荒地;A2层HA/FA比表现为荒地＞苹果梨园.(3)2种土壤紧结态腐殖质含量均随土层深度增加而减小;A1层表现为苹果梨园＜荒地,A2层表现为苹果梨园＞荒地.(4)A1层松结态腐殖质相对含量表现为苹果梨园＞荒地,A2层相反;A1、A2层稳结态腐殖质含量表现为苹果梨园＜荒地;紧结态腐殖质含量相当.苹果梨园松结态腐殖质含量表现为A1＞A2,稳结态腐殖质含量表现为A1＜A2.松/紧比在A1层表现为苹果梨园＞荒地,A2层表现为苹果梨园＜荒地;苹果梨园土壤A1层松结态∶稳结态∶紧结态为3.4∶2.0∶4.6,A2层为2.1∶3.2∶4.7.     

施用碳酸钙对土壤铅、镉、锌交换态含量及在大豆中累积分布的影响

在重金属复合污染的土壤中,通过施用不同水平的碳酸钙对土壤进行改良,研究土壤中Pb、Cd、Zn交换态含量的变化以及在大豆植株中的累积分布.结果表明:(1)在污染土壤中施用碳酸钙,能够降低土壤中Pb、Cd、Zn交换态含量,且随着碳酸钙施用量的增加,土壤中这3种重金属交换态含量呈明显降低趋势.在土壤中施用碳酸钙改善了大豆植株的生长状况,有效地抑制大豆植株对土壤Pb、Cd、Zn的吸收.从而减缓了重金属对大豆植株的毒害作用.(2)2.0 g/kg为碳酸钙的最佳施用量,能使大豆籽粒增产47.5%.籽粒中Pb含量降低73.0%,Cd含量降低53.8%,但在这个重金属污染矿区土壤中施用碳酸钙仍无法使籽粒中的重金属含量达到国家粮食卫生标准中Pb、Cd低于0.2 mg/kg的标准.     

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。     

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.     

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.     

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,     

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.     

Changes in trace element speciation in kola north surface waters during snow melt

The powerful mass-flow of melt water during the brief period of spring thaw provides a surge of pollutants and causes extremely toxic short term conditions. Together with the increase in total metal concentrations during this period, a redistribution in metal speciation occurs that increases the proportion of more toxic forms. Concentrations of ion-exchangeable fractions of nickel (Ni), copper (Cu), aluminium (Al), and manganese (Mn) show strong negative correlations with pH. The sum of complex metal species shows a strong positive correlation with total organic carbon (TOC). A data analysis model based on relationships observed between key parameters and metal behaviour together with gidrological data allowed an assessmrnt of the metal impact on waterbodies from accumulated airborne pollution (Ni, Cu) as well as from accelerated leaching from watersheds (Al, Mn).     

Assessing the effectiveness of conservation measures: Resolving the “wicked” problem of the Steller sea lion

“Wicked” problems are those that are complex and that change when solutions are applied. Many conflicts in conservation fall into this category. The study approached the problem of how to constrain the apparent wickedness of a problem in the conservation management of a species by using simple empirical indicators to carry out iterative assessment of the risk to a population and to document how this risk evolves in relation to the addition of new data and the implementation of management actions. Effects of high levels of uncertainty within data and also concerning population structure were examined through stochastic simulation and by exploration of scenarios. Historical trends in the example used, the Steller sea lion, showed rapid declines in abundance in some regions during the 1980s. The current total population is 130,000-150,000 Steller sea lions through Alaska and British Columbia and this number has been stable since about 1990 in spite of regional differences in population dynamics. Regional differences in the sequence of changes in the number of pups and non-pups, suggested that an internal re-distribution of juveniles could have happened between 1980 and 1990. Current productivity also appears close to the long-term mean. Stochastic population projection using various scenarios showed that, based upon this history, the risk of extinction for the population has declined and is below reasonable thresholds for considering the population to be endangered. The trends in risk suggest that management actions taken since 1990 have probably been effective. Consequently, the conservation management objectives for the Steller sea lion are probably being met. The approach provides a mechanism, based upon experience and scenario analysis, for exploring future policy options and may help to constrain the debate amongst stakeholders about the cost-benefit trade-offs associated with different options.