共查询到20条相似文献，搜索用时 62 毫秒
1.
脱水素(dehydrins,DHNs)是植物胚胎发育后期丰富蛋白(late embriogenesis abundant protein,LEA)中的一类,与低温、干旱以及盐胁迫等多种逆境反应相关.本研究采用cDNA末端快速扩增(rapidamplification of cDNA ends,RACE)技术从茶树(Camellia sinensis)中获得一种茶树脱水素基因CsDHN (GenBank登录号:FJ436978),序列分析显示,该基因cDNA全长960 bp,编码201个氨基酸,推测编码蛋白质分子量约为21kD,等电点为8.3,属于Y3SK2型脱水素.CsDHN基因有2个外显子和1个内含子.生物信息学预测显示,该脱水素蛋白亲水性强、无信号肽和跨膜区,亚细胞定位于细胞质中.表达特性分析表明,CsDHN在逆境及脱落酸(abscisic acid,ABA)诱导下可上调其转录水平,4℃低温处理下表达量可提高4.2倍,而脱水处理能提高93.4倍,高盐处理能提高17.8倍,CsDHN对脱水、高盐胁迫的响应程度优于低温胁迫.CsDHN在茶树各组织器官中都有表达,其中种子中表达量最高,为叶片的11.2倍.研究表明脱水素基因CsDHN可能在茶树防御非生物逆境胁迫和参与茶树种子成熟脱水的活力保护过程起一定作用,为了解茶树抗逆分子机制提供了一定的理论基础. 相似文献
2.
YSK2型脱水素(dehydrins,DHNs)是植物中存在最多的DHNs形式,参与植物响应各种非生物逆境胁迫.为了研究YSK2型DHN的功能,从小麦(Triticum aestivum)中克隆了WDHN1基因(GenBank No.KR709259),该基因编码区序列总长491 bp,含两个外显子和一个内含子,编码133个氨基酸;存在4个保守区域,即1个Y片段、1个S片段和2个K片段,与节节麦(Aegilops tauschii) DHN (EMT30992)亲缘关系最近.通过PCR扩增得到WDHN1启动子序列,该启动子存在2个脱落酸应答元件(abscisic acid (ABA)response element,ABRE)和3个MBS(MYB binding site)生物胁迫响应元件.通过qRT-PCR分析其非生物胁迫下的表达模式,结果表明,在低温、NaC1、ABA和PEG 6000胁迫下,小麦WDHN1基因表达均表现为先上升后下降的趋势,分别于6、60、12和48 h时表达量最高.组织特异性表达分析表明,WDHN1基因在小麦开花后22 d的胚芽中表达量最高,具有明显的组织特异性.将WDHN1基因片段连接于原核表达载体pET28a中,转化大肠杆菌(Escherichia coli) BL21(DE3),用异丙基硫代半乳糖苷(isopropyl β-D-1-thiogalactopyranoside,IPTG)诱导表达,获得20 kD的WDHN1蛋白.对重组大肠杆菌WDHNl-pET28a-BL21(DE3)及其总蛋白进行非生物胁迫,结果表明,WDHNl蛋白还可以阻止蛋白聚合引起的蛋白变性,提高非生物胁迫下大肠杆菌的耐受性及乳酸脱氢酶(lactic dehydrogenase,LDH)的稳定性.研究结果为进一步利用该基因进行小麦抗性改良提供了理论依据. 相似文献
3.
为了研究芹菜质膜内在蛋白基因的序列特征及其在非生物胁迫条件下的表达特性,探讨其抗逆功能,以芹菜品种六合黄心芹为试验材料,通过RT-PCR技术克隆AgPIP2;1基因,通过生物信息学软件分析其核苷酸和氨基酸序列特征,并采用荧光定量PCR技术检测其在不同组织的表达及其对非生物胁迫的响应。结果表明,AgPIP2;1基因含有1个861 bp的开放阅读框,编码286个氨基酸,其编码的蛋白属于PIP2类蛋白。氨基酸序列分析显示,AgPIP2;1含有高度保守的NPA基序以及高等植物PIP蛋白的保守序列,与其他物种PIP2类蛋白具有较高的同源性,与胡萝卜DcPIP2;1的氨基酸序列同源性达到97.90%。在亲缘关系上与大豆GmPIP2;1、胡萝卜DcPIP2;1和绿豆VrPIP2;1较为接近。实时荧光定量PCR技术分析表明,AgPIP2;1基因在芹菜根、叶柄和叶片中均有表达,其中在叶片中的表达量最高,在根中的表达量最低,呈现比较明显的组织特异性。此外,AgPIP2;1基因受到高温、低温、干旱和盐等非生物胁迫的诱导,说明该基因可能参与芹菜抵御非生物胁迫的过程。本研究为进一步了解AgPIP2;1基因的功能及其在非生物胁迫中的作用奠定了基础。 相似文献
4.
耐辐射戈壁异常球菌(Deinococcus gobiensis I-0)是本研究室分离于戈壁沙漠环境中的微生物,对辐射、氧化和干旱等非生物胁迫有超强的抗性。该菌基因组含有2个冷激蛋白编码基因(csp1,Dgo_CA1136和csp2,Dgo_PA0041),编码蛋白均具有典型的冷激蛋白家族特有的结构域。本研究以戈壁异常球菌I-0 Csp1为研究对象,研究表明Csp1能显著增强模式菌株大肠杆菌对低温、高盐、干旱等非生物胁迫的抗性;QRT-PCR分析显示在盐胁迫条件下Csp1表达菌株的海藻糖合成酶基因(otsA和otsB)表达显著上调,其降解基因(treB、treC)无显著变化。Csp1通过调控海藻糖代谢途径,促进渗透保护物的积累,可能是增强细胞盐、干旱等胁迫抗性的有效途径之一。 相似文献
5.
本研究利用RACE技术从真盐生植物海蓬子中获得了高亲和钾离子转运体SbHKT1基因1647bp完整的ORF框。序列分析结果表明,该基因编码548个氨基酸,分子量为62.10kD,理论等电点为9.33;氨基酸序列中第1个～第35个属信号肽序列,第197个～第537个属离子转运体（TrkH）家族特征序列;该基因编码的蛋白具有10个跨膜结构,N端跨膜区及中部膜上呈现明显的疏水性,C端及中部多个跨膜区呈现强疏水性,符合载体类运输蛋白的特点,因此推测SbHKT1蛋白为跨膜运输蛋白。Blast分析显示该蛋白与碱蓬SsHKT1氨基酸同源性高达77%,与冰叶日中花、赤桉和小麦HKT类蛋白的同源性分别为63%、52%和46%。SbHkt1基因表达存在组织特异性：正常生长条件在根、茎中表达较低,在叶片中几乎看不到表达;在高盐低钾的环境下,各组织表达明显升高,高盐低钾胁迫处理8h,其根部表达处于高峰期;经100μmol/L脱落酸处理4h,根部表达达到最高;干旱胁迫（20%PEG6000）处理2h,根部表达量明显上升。由此推断,该基因参与了植物在高盐低钾、渗透、干旱等非生物胁迫下的生理调控。由于目前已克隆的HKT类蛋白基因多来自非盐生植物,对盐生植物内源HKT基因的研究相对较少,因此,海蓬子内源HKT1基因的全长的获得有助于我们进一步研究该基因在高盐钾饥饿环境下运输钾离子,调节植物体内Na＋/K＋平衡的功能,对于揭示真盐生植物的耐盐机制,将其运用于非盐生植物,培育新的耐盐品种具有一定的意义。 相似文献
6.
胡萝卜DcDREB-A6亚族转录因子基因的克隆与非生物胁迫响应分析 总被引：1，自引：0，他引：1
干旱响应元件结合蛋白(dehydration responsive element-binding protein,DREB)类转录因子是干旱应答元件的结合蛋白,在植物响应非生物胁迫时发挥重要作用。本研究基于胡萝卜(Daucus carota L.)转录组数据,检索和拼接获得一个胡萝卜DREB类转录因子基因序列,并根据其序列设计引物,采用RTPCR方法从黑田五寸获得该胡萝卜转录因子基因DcDREB-A6(GenBank登录号:KM386646)。序列分析显示,来源于胡萝卜中的DcDREB-A6基因含有993 bp的开放阅读框,编码330个氨基酸。氨基酸组成成分、理化性质、亲水性/疏水性和三级结构分析结果显示,胡萝卜DcDREB-A6转录因子蛋白质分子量为36.68 kD,等电点为6.00,属于亲水性蛋白。进化树分析显示,DcDREB-A6属于APETLA 2/乙烯反应元件结合蛋白(AP2/ERF)家族转录因子中DREB亚族中的A6组。空间结构表明,该转录因子结构域具有典型的植物AP2/ERF家族转录因子的结构特征,有1个α螺旋和3个β折叠。实时定量荧光PCR证实,胡萝卜DcDREB-A6转录因子基因受高温、低温和高盐胁迫诱导,分别在高温、低温处理4和2 h后表达量增加2倍左右;盐胁迫对其影响较大,处理8 h时,基因表达量增加4.6倍;而干旱胁迫下该基因表达变化幅度相对较小。胡萝卜DcDREB-A6转录因子基因能够响应高温、低温、干旱和高盐等非生物胁迫,本研究结果有助于进一步开展胡萝卜DREB类转录因子的逆境调控研究。 相似文献
7.
α-amylase基因不仅参与植物糖代谢与生物能量的调动,而且与植物抗逆功能相关。为了克隆Bn-α-amylase基因,分析其序列及表达特征,本研究以湘苎3号苎麻(Boehmeria nivea)转录组文库中Unigene4746序列为基础,采用RT-PCR技术克隆该基因的全长编码序列,并进行生物信息学分析;利用Real-time PCR分析该基因在不同组织和不同胁迫条件下的表达特征。研究结果表明,苎麻Bn-α-amylase的编码区序列长2 295 bp,编码765个氨基酸(GenBank登录号:KF860891),推导该蛋白质的等电点和分子量分别为5.685和86.11 kD,该蛋白在羧基端含有两个保守的结构域,亚细胞定位预测显示该蛋白位于细胞质中,不存在信号肽和跨膜结构域。与苹果(Malus×domestic)、拟南芥(Arabidopsis thaliana)、猕猴桃(Actinidia chinensis)、蓖麻(Ricinus communis)、大豆(Glycine max)的α-amylase基因的核苷酸序列相似性分别为80%、76%、76%、73%和67%,与之编码的氨基酸序列相似性分别为68%、65%、65%、69%和51%。进化树分析表明Bn-α-amylase与大豆、葡萄、猕猴桃、蓖麻的α-amylase基因亲缘关系较近,与拟南芥、水稻、高粱的α-amylase基因亲缘关系次之,与卷柏的α-amylase基因亲缘关系较远。实时荧光定量PCR分析表明,Bn-α-amylase在苎麻根、茎皮、茎木质部、茎尖、叶片中均有表达,其中,在叶中表达量最高,在根中表达量最低,且受干旱、高盐胁迫表达增强,受ABA胁迫表达降低。本研究获得了Bn-α-amylase基因的编码区序列,其编码的蛋白具有植物α-amylase典型的结构域,且该基因响应ABA、干旱和高盐逆境胁迫,提示该基因可能与苎麻抗逆境机制密切相关。 相似文献
8.
干旱应答元件结合蛋白(DREB)类转录因子在植物逆境信号转导途径中具有重要的调控作用。为了解AP2/ERF转录因子在茶树逆境胁迫的分子调控机理,本研究从茶树龙井43叶片的cDNA中克隆得到一个编码CsDREB-A2转录因子的基因;对CsDREB-A2基因及其编码蛋白序列特征进行分析,并利用实时荧光定量PCR法检测该基因在茶树不同非生物胁迫处理下的表达水平。结果表明,CsDREB-A2基因开放阅读框为1 056 bp,编码351个氨基酸,其编码氨基酸序列具有AP2保守结构域,包含典型的YRG元件和WLG基序。AP2结构域第14、第19位氨基酸分别为缬氨酸和谷氨酸。拟南芥AP2/ERF家族转录因子的进化分析表明,该转录因子属于DREB亚族的A2组。CsDREB-A2相对分子质量为39 080 Da,理论等电点为5.32,属于亲水性蛋白,主要由α-螺旋和随机卷曲组成,无序化特征明显且存在一个LM无序区域;可能定位于细胞核,不存在信号肽和跨膜结构,属于非分泌蛋白。CsDREB-A2基因在高温(38℃)和干旱(200 g·L-1 PEG)胁迫下均能快速诱导表达,并显著高于对照,分别在处理4、2 h达到最大值,为对照的20.70和42.90倍,植物在渗透胁迫下,可能通过ABA信号途径调节该基因对干旱的耐受性。高盐(200 mmol·L-1 NaCl)胁迫下CsDREB-A2基因的表达受抑制,推测其可能存在负调控结构域降低该基因在盐胁迫下的表达量。本试验结果为研究DREB类转录因子在茶树抗逆胁迫的分子调控机制提供了一定的理论参考。 相似文献
9.
在谷子基因组中鉴定出一个CIPK(Seita.5G145900,命名为SiCIPK19)基因。为揭示SiCIPK19对逆境胁迫的响应,对其基因结构、蛋白特征、功能、进化等性状进行了系统的分析和预测,并用实时定量PCR(RT-qPCR)检测了其在谷子苗期不同逆境及关键生育期干旱胁迫下的表达。结果表明,SiCIPK19基因位于谷子5号染色体,基因组序列长1 353 bp,编码450个氨基酸,基因无可变剪切,且不含内含子。功能域分析和多序列比对发现,SiCIPK19蛋白具有非常保守的序列结构,与其他植物CIPK蛋白也非常相似。RT-qPCR分析表明,SiCIPK19基因被聚乙二醇6000(PEG 6000)、ABA、高盐和低温胁迫强烈诱导。此外,SiCIPK19基因在谷子拔节期、抽穗期和灌浆期干旱条件下参与了对干旱胁迫的响应,推测该基因参与谷子对非生物逆境的应答,尤其在抽穗期和灌浆期干旱胁迫应答中发挥重要作用。本研究结果为进一步分析CIPK基因逆境应答机制,以及利用基因工程方法改善谷子抗逆性和提高产量提供了理论支持。 相似文献
10.
胡萝卜2个DcDREB-A1类转录因子基因的克隆与比较分析 总被引：1，自引：0，他引：1
植物DREB类转录因子在植物抗逆性方面具有重要作用。本文以胡萝卜黑田五寸为材料,基于胡萝卜转录组数据,通过RT-PCR方法克隆出2个DREB-A1类转录因子基因Dc DREB-A1-1和Dc DREBA1-2。序列分析显示,这2个基因均没有内含子,长度分别为780bp和669bp,分别编码259和222个氨基酸;预测其蛋白质相对分子质量分别为29.0KD和24.71KD,p I值分别为4.32和4.63。通过对氨基酸亲水/疏水性进行分析,发现这2个转录因子属于亲水性蛋白。实时定量PCR分析表明,Dc DREB-A1-1和Dc DREB-A1-2基因在胡萝卜不同组织中的表达量不同,分别在叶和根中表达量最高。低温(4℃)、高温(38℃)、盐(0.2 mol·L-1Na Cl)、干旱(200 g·L-1PEG)不同时间段处理表达分析显示,Dc DREB-A1-1在低温、高温、盐和干旱胁迫下被显著诱导,高温、盐和干旱处理1 h后表达量达到最高,分别比对照增加14倍、7倍、7倍,低温处理下2 h表达量最高,是对照的18倍;而Dc DREB-A1-2在高温、低温和盐处理下响应明显,高温处理1 h后表达量为对照的12倍,低温和干旱处理下8 h基因表达量分别比对照增加2.4倍、6.2倍,说明2个基因在响应逆境胁迫时表达不同。胡萝卜响应非生物逆境胁迫是一个复杂的过程,本试验对深入研究胡萝卜抗逆分子机制,提高胡萝卜逆境抗性等方面具有较为重要的意义。 相似文献
11.
低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响 总被引：2，自引：2，他引：0
【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。 相似文献
12.
Aleš Lebeda Ivana Doležalová Eva Křístková Barbora Mieslerová 《Genetic Resources and Crop Evolution》2001,48(2):153-164
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. 相似文献
13.
Kyle Devey Michael Mucalo Gordon Rajendram Joseph Lane 《Communications in Soil Science and Plant Analysis》2015,46(4):72-80
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. 相似文献
14.
Thomas Larsen Jesper Luxhøi Jakob Magid Lars Stoumann Jensen Paul Henning Krogh 《Biology and Fertility of Soils》2007,44(1):59-68
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. 相似文献
15.
《中国生态农业学报》2014,(6)
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, 相似文献
16.
《中国生态农业学报》2014,(7)
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, 相似文献
17.
《中国生态农业学报》2014,(8)
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, 相似文献
18.
M.A. Callaham Jr. J.M. BlairT.C. Todd D.J. KitchenM.R. Whiles 《Soil biology & biochemistry》2003,35(8):1079-1093
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. 相似文献
19.
I.L. Boyd 《Biological conservation》2010,143(7):1664-1674
“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. 相似文献
20.
Soil-profile distribution of primary and secondary plant-available nutrients under conventional and no tillage 总被引：1，自引：0，他引：1
Nutrient distributions under no tillage (NT) compared with conventional disk-and-bed tillage (CT) management in the warm, humid region of the southeastern USA need to be assessed so that future placement, quantity, and type of fertilizers can be altered, if necessary, to efficiently match crop demands. We determined soil-profile distributions of pH, N, P, S, K, Ca, Mg, Na, Zn, Fe, Mn, and Cu to a depth of 0.9 m at the end of 8.5 years of continuous CT and NT management on a Weswood silty clay loam (fine, mixed, thermic Fluventic Ustochrept) in southcentral Texas. Most dramatic changes occurred within the 0–0.05 m depth, where soil under NT had lower pH, Fe, and Cu than under CT, but greater P, K, Zn, and Mn. Greater P and K under NT than under CT also occurred below the till-zone (0.15–0.3 m). At a depth of 0–0.3 m, soil under NT contained greater amounts of extractable P, K, Zn, Fe, Mn, and Cu than under CT. Nitrogen fertilization had little effect on nutrient distributions, except resulting in greater extractable K at 0–0.05 m and greater nitrate at 0–0.15 m. Few changes in soil-profile distributions were observed for extractable S, Ca, Mg, and Na. Long-term continuous use of NT on this fine-textured, high-fertility (except for N) soil had no apparent adverse effects on nutrient distributions relative to CT, but enhanced conservation and availability of P, K, Zn, Fe, Mn, and Cu near the soil surface where crop roots proliferate. 相似文献